The present thesis is based on 14 original articles published in international journals (I-XIV, see page 8) and a summarizing review. The thesis deals with the physiological demands of soccer, with a particular focus on the physiological response to repeated intense exercise. In chapter I the specific issues are presented and in chapter II the physiological demands in soccer are discussed based on the results of the studies performed. Chapter III contains a short survey of the experiments performed to study specifically muscle metabolism and muscle fatigue with repeated intense muscle contractions. With reference to the topics covered in chapters II and III, fatigue during a soccer match is discussed in chapter IV, and chapter V deals with applications for physical training in soccer. Measurements have been performed during soccer matches and training, as well as in experiments simulating the activities of a soccer match. The information obtained has been compared to results from studies of the physical capacity of top-class soccer players and from laboratory experiments aimed at investigating metabolism and fatigue in intermittent exercise. Studies with whole-body and single muscle group exercises have been performed, the latter mainly with the application of a knee-extension model. In the studies on isolated muscle groups, biopsies taken from exercising muscles as well as arterial and femoral venous blood samples have allowed for detailed analysis of muscle ionic transportation and metabolism. In addition, the magnetic resonance technique has been used for the continuous determination of changes in muscle metabolites and pH during intermittent exercise. Analysis of activities during soccer matches showed that a top-class soccer player covers an average distance of approximately 11 km during a match. The distance differs highly between players and is partly related to the position in a team. Midfield players run more at low speed than defenders and forwards, whereas no difference appears to exist between groups when comparing the distance covered at high speed. The distance covered at high speed is the same in the beginning as in the end of a match. The total distance covered by a player during a soccer match is only to a limited extent a measure of the physiological demands on the player during the match. In addition to running, a player is engaged in many other energy demanding activities, i.e. tackling, jumping, accelerating and turning. A more precise evaluation of the total energy demand during a soccer match may be achieved by performing physiological measurements in connection with soccer matches (I).(ABSTRACT TRUNCATED AT 400 WORDS)
Little is known about the relationship between postactivation potentiation (PAP) in human muscles, assessed by enhancement of twitch torque after a conditioning maximal voluntary contraction (MVC), and performance in activities requiring power and speed. Moreover, no studies have assessed PAP in soccer players who train power and endurance simultaneously. The purpose of the present study was to examine the relationship between twitch PAP in knee extensor (KE) muscles, and sprinting and vertical jumping performance in soccer players. Fourteen professional male soccer players with mean (SD) age 20.0 (3.6) years, height 177.9 (6.9) cm and body mass 70.5 (5.7) kg) were tested for 15-m sprint time, vertical jump height in countermovement (CMJ) and squat (SJ) jumps. PAP in KE muscles was induced by a 10-s isometric MVC. Electrically evoked twitches of KE muscles were evoked before and after the conditioning MVC. Immediately after the conditioning MVC, twitch peak torque (PT) and maximal rates of torque development and relaxation were significantly potentiated. A significant negative correlation was found between 15-m sprint time and jump height in CMJ (r = -0.63) and SJ (r = -0.57). PAP of twitch PT correlated significantly positively with jump height in CMJ (r = 0.61) and SJ (r = 0.64), and negatively with 15-m sprint time (r = -0.59). In conclusion, twitch PAP in KE muscles was significantly correlated with performance in vertical jumping and sprinting in male professional soccer players, whereas the magnitude of PAP in soccer players was similar to that observed previously in power-trained athletes.
The aims of this study were to (1) determine the activity profiles of a large sample of English FA Premier League soccer players and (2) examine high-intensity running during elite-standard soccer matches for players in various playing positions. Twenty-eight English FA Premier League games were analysed during the 2005-2006 competitive season (n=370), using a multi-camera computerised tracking system. During a typical match, wide midfielders (3138 m, s=565) covered a greater distance in high-intensity running than central midfielders (2825 m, s= 73, P=0.04), full-backs (2605 m, s=387, P < 0.01), attackers (2341 m, s=575, P < 0.01), and central defenders (1834 m, s=256, P < 0.01). In the last 15 min of a game, high-intensity running distance was approximately 20% less than in the first 15-min period for wide midfielders (467 m, s=104 vs. 589 m, s=134, P < 0.01), central midfielders (429 m, s=106 vs. 534 m, s=99, P < 0.01), full-backs (389 m, s=95 vs. 481 m, s=114, P < 0.01), attackers (348 m, s=105 vs. 438 m, s=129, P < 0.01), and central defenders (276 m, s=93 vs. 344 m, s=80, P < 0.01). There was a similar distance deficit for high-intensity running with (148 m, s=78 vs. 193 m, s=96, P < 0.01) and without ball possession (229 m, s=85 vs. 278 m, s=97, P < 0.01) between the last 15-min and first 15-min period of the game. Mean recovery time between very high-intensity running bouts was 72 s (s=28), with a 28% longer recovery time during the last 15 min than the first 15 min of the game (83 s, s=26 vs. 65 s, s=20, P < 0.01). The decline in high-intensity running immediately after the most intense 5-min period was more evident in attackers (216 m, s=50 vs. 113 m, s=47, P < 0.01) and central defenders (182 m, s=26 vs. 96 m, s=39, P < 0.01). The results suggest that high-intensity running with and without ball possession is reduced during various phases of elite-standard soccer matches and the activity profiles and fatigue patterns vary among playing positions. The current findings provide valuable information about the high-intensity running patterns of a large sample of elite-standard soccer players, which could be useful in the development and prescription of specific training regimes.
Abstract We examined the physical demands of small-sided soccer games in untrained middle-age males and muscle adaptations and performance effects over 12 weeks of recreational soccer training in comparison with continuous running. Thirty-eight healthy subjects (20–43 years) were randomized into a soccer (SO), running (RU) and control (CO) group. Two–three weekly 1-h training sessions were performed. Muscle lactate (30.1 ± 4.1 vs. 15.6 ± 3.3 mmol/kg d.w.), blood lactate, blood glucose and time above 90% HRmax (20 ± 4% vs. 1 ± 1%) were higher (p < 0.05) during training in SO than in RU. After 12 weeks of training, quadriceps muscle mass and mean muscle fibre area were 9 and 15% larger (p < 0.05) in SO, but unaltered in RU, and in SO, the fraction of FTx fibres was lowered (10.7 ± 1.8 vs. 17.9 ± 3.2%). In SO, citrate synthase activity was 10 and 14% higher (p < 0.05) after 4 and 12 weeks, but unaltered in RU. After 4 weeks VO2max and Yo-Yo IE2 performance were elevated (p < 0.05) to a similar extent in SO (7 and 37%) and RU (6 and 36%) but increased further (p < 0.05) from 4 to 12 weeks in SO (6 and 23%). In SO, 30-m sprint performance was improved (p < 0.05) by 0.11 ± 0.02 s. Blood lactate during running at 11 km/h was lowered (p < 0.05) from 0 to 4 and 4 to 12 weeks (2.6 ± 0.3 vs. 3.8 ± 0.6 vs. 6.1 ± 0.9 mM) and from 0 to 12 weeks in RU. No changes occurred for CO. In conclusion, recreational soccer organized as small-sided games stimulates both aerobic and anaerobic energy turnover and is an effective type of training leading to significant cardiovascular and muscular adaptations as well as performance enhancements throughout a 12-week training period.
Background: Female athletes are 2 to 8 times more likely than male athletes to injure the anterior cruciate ligament during a non-contact athletic maneuver. Identifying anterior cruciate ligament injury risk factors in female athletes may help with the development of preventive training programs aimed at reducing injury rates.
Hypothesis: Differences between genders in lower limb kinematics, kinetics, and neuromuscular patterns will be identified in an adolescent soccer population during an unanticipated side-cut maneuver.
Study Design: Controlled laboratory study.
Methods: Forty-two elite adolescent soccer players (21 male and 21 female) performed an unanticipated side-cut maneuver, with the 3-dimensional kinematic, kinetic, and electromyographic lower limb data being analyzed using principal component analysis.
Results: The female athletes had higher gastrocnemius activity, normalized to maximal voluntary isometric contractions, and a mediolateral gastrocnemius activation imbalance that was not present in the male athletes during early stance to midstance of the side-cut. Female athletes demonstrated greater rectus femoris muscle activity throughout stance, and the only hamstring difference identified was a mediolateral activation imbalance in male athletes only. Female athletes performed the side-cut with less hip flexion and more hip external rotation and also generated a smaller hip flexion moment compared with the male athletes.
Conclusion: This is the first study to identify gender-related differences in gastrocnemius muscle activity during an unanticipated cutting maneuver.
Clinical Relevance: The increased and imbalanced gastrocnemius muscle activity, combined with increased rectus femoris muscle activity and reduced hip flexion angles and moments in female subjects, may all have important contributing roles in the higher noncontact ACL injury rates observed in female athletes.
Objective: The lower impact on the musculoskeletal system induced by plyometric exercise on sand compared to a firm surface might be useful to reduce the stress of intensified training periods or during rehabilitation from injury. The aim of this study was to compare the effects of plyometric training on sand versus a grass surface on muscle soreness, vertical jump height and sprinting ability.
Design: Parallel two-group, randomised, longitudinal (pretest‚àípost-test) study.
Methods: After random allocation, 18 soccer players completed 4 weeks of plyometric training on grass (grass group) and 19 players on sand (sand group). Before and after plyometric training, 10 m and 20 m sprint time, squat jump (SJ), countermovement jump (CMJ), and eccentric utilization ratio (CMJ/SJ) were determined. Muscle soreness was measured using a Likert scale.
Results: No training surface ?ó time interactions were found for sprint time (p>0.87), whereas a trend was found for SJ (p‚Ää=‚Ää0.08), with both groups showing similar improvements (p<0.001). On the other hand, the grass group improved their CMJ (p‚Ää=‚Ää0.033) and CMJ/SJ (p‚Ää=‚Ää0.005) significantly (p<0.001) more than players in the sand group. In contrast, players in the sand group experienced less muscle soreness than those in the grass group (p<0.001).
Conclusions: Plyometric training on sand improved both jumping and sprinting ability and induced less muscle soreness. A grass surface seems to be superior in enhancing CMJ performance while the sand surface showed a greater improvement in SJ. Therefore, plyometric training on different surfaces may be associated with different training-induced effects on some neuromuscular factors related to the efficiency of the stretch-shortening cycle.
Abstract:
Numerous studies have suggested that dehydration is a causal factor to fatigue across a range of sports such as soccer; however, empirical evidence is equivocal on this point. It is also possible that exercise-induced moderate dehydration is purely an outcome of significant metabolic activity during a game. The diverse yet sustained physical activities in soccer undoubtedly threaten homeostasis, but research suggests that under most environmental conditions, match-play fluid loss is minimal (∼1-2% loss of body mass), metabolite accumulation remains fairly constant, and core temperatures do not reach levels considered sufficiently critical to require the immediate cessation of exercise. A complex (central) metabolic control system which ensures that no one (peripheral) physiological system is maximally utilized may explain the diversity of research findings concerning the impact of individual factors such as dehydration on elite soccer performance. In consideration of the existing literature, we propose a new interpretative pacing model to explain the self-regulation of elite soccer performance and, in which, players behaviourally modulate efforts according to a subconscious strategy. This strategy is based on both pre-match (intrinsic and extrinsic factors) and dynamic considerations during the game (such as skin temperature, thirst, accumulation of metabolites in the muscles, plasma osmolality and substrate availability), which enables players to avoid total failure of any single peripheral physiological system either prematurely or at the conclusion of a match. In summary, we suggest that dehydration is only an outcome of complex physiological control (operating a pacing plan) and no single metabolic factor is causal of fatigue in elite soccer.
Probably just due to the special attention that people pay to soccer players, the narcissism in them must be more than normal people. The aim of current research is the comparison of narcissism between the soccer players who play in different levels and the lay people.
This research is descriptive. Target population included of all players who play in different levels in Isfahan, for this purpose 115 subjects of three groups of football players from different clubs, universities and some university students containing 36 soccer club players, 34 university soccer players and 45 university students chosen randomly. Data are gathered using the narcissism scale of Ruskin and Terry and the Personality Questionnaire of Eyseneck (EPQ) and was analyzed by the use of analysis of variance (ANOVA) and the follow-up of Newman-Kweles. The result of the research signified a significant difference in the results of narcissism scale between the club soccer players and the other two groups (P£0.05).
There was a significant difference in extroversion between the normal university students and other two groups, and also in neuroticism between club football players and other two groups (P£0.05). In psychoticism, the club football players gained higher scores than the other two groups (P£0.05).
Where as there was no significant difference between the two other groups (university soccer players and the normal student).
Football (soccer) training and matches are scheduled at different times throughout the day. Association football involves a variety of fitness components as well as psychomotor and game‚Äêrelated cognitive skills. The purpose of the present research, consisting of two separate studies, was to determine whether game‚Äêrelated skills varied with time of day in phase with global markers of both performance and the body clock. In the first study, eight diurnally active male association football players (19.1¬±1.9 yrs of age; mean¬±SD) with 10.8¬±2.1 yrs playing experience participated. Measurements were made on different days at 08:00, 12:00, 16:00, and 20:00 h in a counterbalanced manner. Time‚Äêof‚Äêday changes in intra‚Äêaural temperature (used as a marker of the body clock), grip strength, reaction times, flexibility (markers of aspects of performance), juggling and dribbling tasks, and wall‚Äêvolley test (football‚Äêspecific skills) were compared. Significant (repeated measures analysis of variance, ANOVA) diurnal variations were found for body temperature (p<0.0005), choice reaction time (p<0.05), self‚Äêrated alertness (p<0.0005), fatigue (p<0.05), forward (sit‚Äêand‚Äêreach) flexibility (p<0.02), and right-hand grip strength (p<0.02), but not left-hand grip strength (p=0.40) nor whole‚Äêbody (stand‚Äêand‚Äêreach) flexibility (p=0.07). Alertness was highest and fatigue lowest at 20:00 h. Football‚Äêspecific skills of juggling performance showed significant diurnal variation (p<0.05, peak at 16:00 h), whereas performance on the wall‚Äêvolley test tended to peak at 20:00 h and dribbling showed no time‚Äêof‚Äêday effect (p=0.55). In a second study, eight diurnally active subjects (23.0¬±0.7 yrs of age) completed five test sessions, at the same times as in the first study but with a second session at 08:00 h. Test‚Äêre‚Äêtest comparisons at 08:00 h for all components indicated good reliability. Intra‚Äêaural temperature showed a significant time‚Äêof‚Äêday effect (p<0.001) with mean temperature at 16:00 h (36.4¬?C) higher than at 08:00 h (35.4¬?C). There was no significant effect of chronotype on the temperature acrophase (peak time) (p>0.05). Diurnal variation was found for performance tests, including sit‚Äêand‚Äêreach flexibility (p<0.01) and spinal hyper‚Äêextension (p<0.05). Peaks occurred between 16:00 and 20:00 h and the daytime changes paralleled the temperature rhythm. Diurnal variation was also found for football‚Äêspecific tests, including dribbling time (p<0.001, peak at 20:00 h) and chip test performance (p<0.01), being more accurate at 16:00 h (mean error=0.75 m) than at 08:00 h (mean error=1.01 m). Results indicate football players perform at an optimum between 16:00 and 20:00 h when not only football‚Äêspecific skills but also measures of physical performance are at their peak. Body temperature peaked at a similar time, but positive mood states seemed to peak slightly earlier. While causal links cannot be established in these experiments, the results indicate that the diurnal variation of some aspects of football performance is affected by factor(s) other than body temperature alone.
STUDY DESIGN: Controlled laboratory study. OBJECTIVES: To quantify phase duration and lower extremity muscle activation and alignment during the most common types of soccer kick-the instep kick and side-foot kick. A second purpose was to test the hypotheses that different patterns of lower extremity muscle activation occur between the 2 types of kicks and between the kicking limb compared to the support limb. BACKGROUND: Soccer players are at risk for lower extremity injury, especially at the knee. Kicking the soccer ball is an essential, common, and distinctive part of a soccer player's activity that plays a role in soccer player injury. Regaining the ability to kick is also essential for soccer athletes to return to play after injury. METHODS: Thirteen male soccer players underwent video motion analysis and electromyography (EMG) of 7 muscles in both the kicking and supporting lower extremity (iliacus, gluteus maximus, gluteus medius, vastus lateralis, vastus medialis, hamstrings, gastrocnemius) and 2 additional muscles in the kicking limb only (hip adductors, tibialis anterior). Five instep and 5 side-foot kicks were recorded for each player. Analysis-of-variance models were used to compare EMG activity between type of kicks and between the kicking and nonkicking lower extremity. RESULTS: Five phases of kicking were identified: (1) preparation, (2) backswing, (3) limb cocking, (4) acceleration, and (5) follow-through. Comparing the kicking limb between the 2 types of kick, significant interaction effects were identified for the hamstrings (P = .02) and the tibialis anterior (P<.01). Greater activation of the kicking limb iliacus (P<.01), gastrocnemius (P<.01), vastus medialis (P = .016), and hip adductors (P<.01) occurred during the instep kick. Significant differences were seen between the kicking limb and the support limb for all muscles during both types of kick. CONCLUSIONS: Certain lower extremity muscle groups face different demands during the soccer instep kick compared to the soccer side-foot kick. Similarly, the support limb muscles face different demands than the kicking limb during both kicks. Better definition of lower extremity function during kicking provides a basis for improved insight into soccer player performance, injury prevention, and rehabilitation.
Objectives: To assess the frequency and quantity of usage of permitted drugs by Italian professional soccer players.
Methods: A cohort of 1041 professional soccer players from the two Italian major leagues was assembled during the season 2003–4; 743 of the 785 (94.6%) subjects available on the day of the interview answered an epidemiological questionnaire, which included questions on the type and frequency of use of several permitted drugs.
Results: 92.6% of players reported having used oral anti-inflammatory products in the previous year, and most of them were current users (86.1%). 36% of the players, mostly current users, reported the use of analgesics. 82.8% of the players reported current use of supplements, and 28% reported using vitamins.
Conclusions: The regular use of several permitted drugs is very high among professional soccer players. The description of players’ behaviour is the first step towards regular monitoring of the players’ need for, and use of, vitamins, supplements and other permitted drugs.
The present study examined the fatigue development in muscle mechanical properties with emphasis on rapid force characteristics and neuromuscular activity in response to high level soccer match play. Young elite soccer players (n=9) were tested before (CON) and after (POST) a soccer match for maximal knee extensor and flexor isometric strength (MVC) and contractile rate of force development (RFD) with synchronous surface electromyography (EMG) recording. Furthermore, maximal vertical jump power and related parameters were assessed. Isometric knee extensor and flexor MVC decreased ∼10% (p≤0.01) along with a right-shift in the moment-time curve. RFD decreased ∼9% (0-200 ms) for the knee flexors while there was a tendency towards reduced RFD during knee extension following soccer match play. Similar reductions were observed for some but not all selected EMG parameters during the MVC and RFD tests. Mechanical jump parameters generally remained unchanged post match play. This study is the first to examine the fatigue induced changes in rapid muscle force production (RFD) induced by soccer match play. The observed decrement in rapid muscle force capacity is likely to have negative impact on performance in explosive playing actions (i.e. accelerations, kicking, sprinting) that typically is involved in soccer match play.
The role of the referee is far from minimal in the economy of soccer, as very often, particularly in professional soccer, a wrong judgment may have profound implications on the outcome of the game. In this regard, a better knowledge of soccer refereeing can obviously benefit the game. Recent studies have shown that during a competitive match, an elite soccer referee may cover 9-13km attaining approximately 85-90% and approximately 70-80% of maximal heart rate and maximal oxygen uptake (V-dotO2max), respectively. Of the total distance covered about 4-18% is covered at high intensity. Blood lactate concentration has been reported to be in the range of 4-5 mmol/L; however, during competitive matches, blood lactate concentrations as high as 14 mmol/L have been observed. This figure is similar to that extensively reported for soccer players, specifically paralleling that observed in midfield players. However, compared with players, referees are 15-20 years older, often have a non-professional status and cannot be substituted during the game. Furthermore, this important physical stress superimposes onto a high perceptual-cognitive workload throughout the entire game. In relation to fitness status, referees possess V-dotO2max values somewhat lower than the players they officiate, with mean values in the range of 44-50 mL/kg/min. However, the methods used by the Federation Internationale de Football Association and the Union of European Football Associations to test referee fitness need to be changed as the current fitness tests do not relate to match performance. More task-specific tests such as the Yo-Yo Intermittent Recovery Test (YYIRT) have been devised and validated for use with referees. Given that aerobic performance is positively correlated with match performance, it is important that referees are trained to improve their ability to cover large distances during a match and also to repeat high-intensity efforts. A number of studies have shown large improvements in YYIRT performance following both short-term (12 weeks) and long-term (16 months) high-intensity interval training. Future research needs to focus on a number of important areas including the decision-making ability of referees when officiating under different conditions, such as high thermal strain, and the impact of age on both physical and mental performance.
With the methods of documentary review,investigations,and statistical analysis,the status quo of Chinese juvenile soccer is researched including training-administering mechanism,team's status,training and competition mechanism,investment,construction of the training theory and rule of law.The results show that the main problems of Chinese juvenile soccer at present are as follows: an absence of strategy concern to juvenile soccer,faultiness of administering and operating mechanism,ambiguity of the training guidelines,ignoring the rules of juvenile growing and cultivation,being eager for quick success and instant benefit,the low level of the coaches as a whole,and the lag of the coaches' cultivation.Some corresponding suggestions are put forward.
Failure to recover fully between sessions has been suggested to cause immunodepression. Therefore, the cumulative effects of soccer-specific intermittent exercise undertaken on different days 48 h apart on salivary IgA, cortisol and total protein concentration were investigated. Nine male subjects completed two trials of soccer-specific intermittent exercise 48 h apart on a motorised treadmill. Timed unstimulated saliva samples were collected immediately before and after exercise, and 24 and 48 h post-exercise. Salivary IgA concentration (EX (1): 215 +/- 160 to 335 +/- 246 and EX (2): 144 +/- 93 to 271 +/- 185 mg . l (-1), p = 0.007), osmolality (p = 0.001) and total protein (p = 0.001) increased immediately following exercise in both trials and decreased 24 h afterwards, whereas saliva flow rate decreased significantly (p = 0.015) before returning to pre-exercise values 24 h postexercise. The IgA secretion rate, IgA to osmolality ratio, IgA to total protein, solute secretion rate, total protein secretion rate, and cortisol did not differ between the time-points. The results suggest that performing two bouts of moderate intensity soccer-specific intermittent exercise 48 h apart does not suppress resting salivary IgA concentration significantly although a small progressive reduction in salivary IgA was observed. These findings may not extend to successive competitive soccer games when vulnerable players might experience clinically relevant reductions in s-IgA.
Longitudinal changes in height, weight and physical performance were studied in 33 Flemish male youth soccer players from
the Ghent Youth Soccer Project. The players‚Äô ages at the start of the study ranged from 10.4 to 13.7 years, with a mean age of 12.2 +0.7 years. Longitudinal changes were studied over a 5 year period. Peak height velocity and peak weight velocity were determined using non-smoothed polynomials. The estimations of peak height velocity, peak weight velocity and age at peak height velocity were 9.7 +1.5 cm ?Å year71, 8.4 + 3.0 kg ?Å year71 and 13.8 +0.8 years, respectively. Peak weight velocity occurred, on average, at the same age as peak height velocity. Balance, speed of limb movement, trunk strength, upper-body muscular endurance, explosive strength, running speed and agility, cardiorespiratory endurance and anaerobic capacity showed peak development at peak height velocity. A plateau in the velocity curves was observed after peak height velocity for upper-body muscular endurance, explosive strength and running speed. Flexibility exhibited peak development during the tear after peak height velocity. Trainers and coaches should be aware of the individual characteristics of the adolescent growth spurt and the training load should also be individualized at this time
In this cross-sectional study, the differences in the isokinetic peak torque of the knee joint muscles (dominant and non-dominant) were investigated in three groups of youths (n=45; age, 14.9±1.1 years) with different soccer training backgrounds. Significant main effects were observed for training background on the functional hamstrings to quadriceps ratios for knee flexion (HCON:QECC ratio; F2,42=4.023, P=0.025) and extension (HECC:QCON ratio; F2,42=8.53, P<0.001) at 4.32 rad/s. Post hoc tests indicated that both ratios were significantly different between conventionally trained players compared with resistance-trained players and controls (mean±SD; HECC:QCON ratio, dominant limb; 0.91±0.10; 1.04±0.12; 1.10±0.22; non-dominant limb; 0.89±0.09; 1.05±0.19; 1.06±0.15; HCON:QECC ratio, dominant limb; 0.36±0.06; 0.34±0.07; 0.30±0.08; non-dominant limb; 0.33±0.05; 0.32±0.08; 0.28±0.07).Results suggest that the muscle-loading patterns experienced in youth soccer may alter the reciprocal balance of strength about the knee under high-velocity conditions. The findings also indicate that these balances may be improved by incorporating resistance training into the habitual exercise routines of youth soccer players.
Elite soccer players spend a substantial amount of time trying to improve physical capacities, including aerobic endurance
and strength and the strength derivatives of speed and power. The average oxygen uptake for international soccer teams
ranges from 55 to 68 ml ?ó kg
71 ?ó min71
and the half-squat maximal strength from 120 to 180 kg. These values are similar to
those found in other team sports. Recently, it has been shown that the heart’s stroke volume is the element in the oxygen
chain that mainly limits aerobic endurance for athletes. These findings have given rise to more intensive training
interventions to secure high stroke volumes, which, in turn, have proved positive in changing both maximal oxygen
consumption and soccer performance in terms of distance covered, contacts with the ball and number of sprints in a game.
The training employed has consisted of 4 6 4-min ‘‘intervals’’ running uphill at 90 – 95% of maximal heart rate interspersed with 3 min jogging at 70% of maximal heart rate to facilitate removal of lactate. Research has revealed that a soccer-specific training routine with the ball might be as effective as plain running. Strength training to produce neural adaptations has been effective in changing not only strength in terms of ‘‘one-repetition maximum’’, but also sprinting velocity and jumping height, in elite soccer players without any change in body mass. The same training has also improved running economy and thus aerobic endurance performance. The training regimen used for a European Champions League team was 4 6 4 repetitions of half-squats with the emphasis on maximal mobilization of force in the concentric action
The purpose of this study was to examine the physiological effects of different sprint repetition protocols on professional footballers. Of particular interest were the abilities of repeated sprint protocols to induce fatigue to an extent observed during competitive soccer. Six professional soccer players were assessed for fatigue rate and physiological responses of heart rate (HR), blood lactate (BLa), and rating of perceived exertion (RPE) during the performance of 4 repeated sprint drills, each totaling a sprint distance of 600 m. The 4 drills used 15-or 40-m sprints with 1:4 or 1:6 exercise: rest ratios. The 15-m sprint drill with 1:4 exercise:rest ratio induced the greatest fatigue (final sprint time 15% greater than initial sprint time) and greatest physiological responses. The 40-m sprint drill using a 1:4 exercise:rest ratio produced similar BLa and HR responses to the 15-m drill (13-14 mmol[middle dot]L-1 and 89% HRmax, respectively) but significantly lower RPE (mean +/- SD: 17.1 +/- 0.4 vs. 18.8 +/- 0.4, p < 0.05) and fatigue rates (11.1 vs. 15.0%, p < 0.01). Both sprint distance and exercise:rest ratio independently influenced fatigue rate, with the 15-m sprint distance and the 1:4 exercise:rest ratio inducing significantly (p < 0.01) greater fatigue than the 40-m sprint distance and the 1:6 exercise:rest ratio. The magnitude of fatigue during the 40- X 15-m sprint drill using a 1:6 exercise:rest ratio was 7.5%, which is close to the fatigue rate previously reported during actual soccer play. The present study is the first to examine both variations in sprint distances and rest ratios simultaneously, and the findings may aid the design of repeated sprint training for soccer.
Performance over very short distances (1-5 m) is important in soccer. We investigated this in 23 male regional-level soccer players aged 17.2 +/- 0.7 years, filming body markers to determine the average velocity and acceleration over the first step (V(S) and A(S)) and the first 5 m (V(5), A(5)). Data were related to scores on a force-velocity test, squat jump (SJ), countermovement jump (CMJ), and 1 maximal repetition (1 RM) half back squat. Leg and thigh muscle volumes were also assessed anthropometrically. V(5) was positively correlated with leg and thigh muscle volumes (r = 0.61, p < 0.05; r = 0.43, p < 0.05, respectively), SJ power (absolute and relative to body mass, r = 0.45, p < 0.05; r = 0.43, p < 0.05, respectively), absolute force-velocity leg power (r = 0.49, p < 0.05), and 1 RM half back squat (r = 0.66, p < 0.001). The use of dimensional exponents did not change coefficients materially. V(S) was also correlated with leg muscle volume and 1 RM back half squat (r = 0.56, p < 0.01; r = 0.58, p < 0.01, respectively) and more weakly with force-velocity leg power and SJ force (r = 0.49, p < 0.05; r = 0.46, p < 0.5, respectively). However, the CMJ was unrelated to velocity or acceleration. Sprinting ability is correlated with measures of power and force such as the force-velocity test, SJ, and 1 RM half back squat; such measures thus offer useful guidance to soccer coaches who wish to improve the short-distance velocity of their players.
It has been suggested that several parameters of mucosal immunity, including salivary immunoglobulin A (s-IgA), are affected by heavy exercise either in field sports or in the laboratory environment. Few observations have been made during a true sporting environment, particularly in professional soccer. We tested the hypothesis that salivary IgA levels will be decreased after a 70-minute regulation in a top-level professional soccer friendly match. Saliva samples from 24 male professional soccer players collected before and after the match were analyzed. Salivary immunoglobulin A concentration was measured by enzyme-linked immunosorbent assay and expressed as the absolute concentration (s-IgAabs), s-IgA relative to total protein concentration (IgA-Pro), and the secretion rate of IgA (s-IgArate). Rate of perceived exertion (RPE) was used to monitor the exercise intensity. The paired t-test showed no significant changes in s-IgAabs and s-IgArate (p > 0.05) from PRE to POST match. However, a significant (p < 0.05) increase in total protein concentration (1.46 ± 0.4 to 2.00 ± 07) and a decrease in IgA-Pro were observed. The best and most significant correlation was obtained with the RPE and changes in IgA-Pro (rs = −0.43) and could indicate that this expression may be an interesting marker of intensity in a soccer match. However, further investigation regarding exercise intensity, protein concentration, and immune suppression, particularly in team sports, is warranted. From a practical application, the variability of the responses among the players leads us to suggest that there is a need to individually analyze the results with team sports. Some athletes showed a decrease in s-IgA expressions, suggesting the need for taking protective actions to minimize contact with cold viruses or even reducing the training load.
The Running-Based Anaerobic Sprint Test (RAST) is an important tool for prescribing and monitoring training. The aim of this study was to evaluate cardiovascular changes by the variables heart rate and blood pressure in soccer players tested with RAST. A trial with 20 soccer players who trained daily and participated in sub-18 soccer championships. The heart rate (HR) was collected at rest (before warming) and right after the end of the test, as well as the systolic (SBP) and diastolic (DBP) blood pressure. For statistics it was used the paired t-test with p<0.05. The collected data show that the values at resting time point can be considered normal for healthy young people and after the test it was observed that the HR and SBP increased significantly as compared with resting time, and the DPB presented no statistically changes. Conclusion: The results showed that the cardiovascular changes occurring in the RAST test, which is an effort with anaerobic features, are similar to changes in high-intensity aerobic efforts.
Background: Eccentric hip adduction and abduction strength plays an important role in the treatment and prevention of groin injuries in soccer players. Lower extremity strength deficits of less than 10% on the injured side, compared to the uninjured side has been suggested as the clinical milestone before returning to sport following injury.
Objective: To examine whether a side-to-side eccentric hip adduction or abduction strength symmetry can be assumed in non-injured soccer players and matched controls.
Material and method: Nine elite soccer players 19.4 (1.5) years and nine recreational athletes 19.5 (2.0) years matched for gender, height and weight were included. Eccentric hip adduction and abduction strength of the dominant and non-dominant leg was tested for all the participants using an eccentric break test with a hand-held dynamometer.
Results: The dominant leg was 14% stronger than the non-dominant leg for hip adduction in the soccer players (p<0.05). No other side-to-side strength differences existed in soccer players or controls. In soccer players, hip abduction strength was 17-30% greater than controls for the dominant (p<0.05) and non-dominant leg (p<0.001).
Conclusion: Eccentric hip adduction strength was greater in the dominant leg than in the non-dominant leg in soccer players, but not in matched controls. Eccentric hip abduction strength was greater in soccer players than matched controls, but soccer does not seem to induce a similar eccentric strength adaptation in the hip adductors.
Accessory soleus is a rare congenital anatomical variant, which may manifest in the second/third decade of life as an exertional ankle pain and swelling or as an asymptomatic postero-medial mass. The incidence of this condition ranges from 0.7 to 5.5%. Many treatment options have been described in literature, including conservative treatment, excision, fasciotomy, release and closure of blood supply. We report a symptomatic massive accessory soleus (17 ?ó 5 ?ó 4 cm) in an 18-year-old male semi-professional soccer player. Excision of the accessory soleus was performed. The patient went back to the game 3 months after surgery. The literature review stated that either fasciotomy or excision of the muscle produce good results in the athletes.
The hypothesis of this study was that soccer players and dancers have different balance abilities and that these differences could be objectively measured using center of pressure measurements.
Background
Center of pressure (COP) measurements are reproducible and have been validated in the literature for assessing standing balance. The literature does not provide sensitive enough techniques for discriminating between two groups of athletes with excellent standing balance.
Methods and measures
A Matscan pressure mat (Tekscan, Boston, MA) was used to compare COP change variability between 32 female collegiate soccer players and 32 dancers. COP was used to calculate sway index, center acquisition time, sway path length and sway velocity as measures of standing balance.
Results
The dancers had significantly better balance scores (p<0.05) in 5 of 20 balance tests. Results for the remaining 15 balance tests were not significantly different.
Conclusion
These data show that standing balance characteristics of dancers and soccer players can be objectively measured using COP data. Dancers have certain standing balance abilities that are better than those of soccer players. The COP measurements in this study can be used as a tool in future studies investigating standing balance in different groups of athletes.
The aim of the study was to investigate the reliability of a new test of soccer performance and evaluate the effect of carbohydrate (CHO) on soccer performance. Eleven university footballers were recruited and underwent 3 trials in a randomized order. Two of the trials involved ingesting a placebo beverage, and the other, a 7.5% maltodextrin solution. The protocol comprised a series of ten 6-min exercise blocks on an outdoor Astroturf pitch, separated by the performance of 2 of the 4 soccer-specific tests, making the protocol 90 min in duration. The intensity of the exercise was designed to be similar to the typical activity pattern during soccer match play. Participants performed skill tests of dribbling, agility, heading, and shooting throughout the protocol. The coefficients of variation for dribbling, agility, heading, and shooting were 2.2%, 1.2%, 7.0%, and 2.8%, respectively. The mean combined placebo scores were 42.4 +/- 2.7 s, 43.1 +/- 3.7 s, 210 +/- 34 cm, and 212 +/- 17 points for agility, dribbling, heading, and kicking, respectively. CHO ingestion led to a combined agility time of 41.5 +/- 0.8 s, for dribbling 41.7 +/- 3.5 s, 213 +/- 11 cm for heading, and 220 +/- 5 points for kicking accuracy. There was a significant improvement in performance for dribbling, agility, and shooting (p < .05) when CHO was ingested compared with placebo. In conclusion, the protocol is a reliable test of soccer performance, and ingesting CHO leads to an improvement in soccer performance.
The aim of the present study was to examine differences in thigh muscularity and dynamic torque between elite junior (15.7 +/- 0.2 years) and senior (22.6 +/- 2.4 years) soccer players. Cross-sectional areas of the total muscle compartment, quadriceps femoris, and hamstrings + adductors were determined using magnetic resonance imaging. Knee extension and flexion torque were also measured at 1.05 and 3.14 rad . s(-1). Neither junior nor senior players showed significant differences in cross-sectional area or torque between the dominant and non-dominant leg. The quadriceps femoris and hamstrings + adductors were significantly greater in the senior than junior players at all thigh-slice sites. The percentage of quadriceps femoris to total muscle compartment was significantly higher in the junior than the senior players, and the corresponding value of hamstrings + adductors was significant in the reverse direction. The senior players showed greater torque than the juniors regardless of motion and velocity, even in terms of torque relative to the product of the cross-sectional area and height. The present results indicate that (1) senior players are characterized by the predominant development of hamstrings and adductors and a higher dynamic torque relative to muscle size, and (2) elite soccer players did not show asymmetry in terms of the muscularity or dynamic torque of the thigh muscles irrespective of age.
Background and objectives: Urinary steroid profiling is used in doping controls to detect testosterone abuse. A testosterone over epitestosterone (T/E) ratio exceeding 4.0 is considered as suspicious of testosterone administration, irrespectively of individual heterogeneous factors such as the athlete’s ethnicity. A deletion polymorphism in the UGT2B17 gene was demonstrated to account for a significant part of the inter-individual variability in the T/E between Caucasians and Asians. Here, we examined the variability of urinary steroid profiles in a widely heterogeneous cohort of professional soccer players. Method: The steroid profile of 57 Africans, 32 Asians, 50 Caucasians and 32 Hispanics was determined by gas chromatography-mass spectrometry. Results: Significant differences have been observed between all ethnic groups. After estimation of the prevalence of the UGT2B17 deletion/deletion genotype (African:22%; Asian:81%; Caucasian:10%; Hispanic:7%), ethnic-specific thresholds were developed for a specificity of 99% for the T/E (African:5.6; Asian:3.8; Caucasian:5.7; Hispanic:5.8). Finally, another polymorphism could be hypothesized in Asians based on specific concentrations ratio of 5a-/5b-androstane-3a,17b-diol in urine. Conclusion: These results demonstrate that a unique and nonspecific threshold to evidence testosterone misuse is not fit for purpose. An athlete's endocrinological passport consisting of a longitudinal follow-up together with the ethnicity and/or the genotype would strongly enhance the detection of testosterone abuse. Finally, additional genotyping studies should be undertaken to determine if the remaining unexplained disparities have an environmental or a genetic origin.
Background: The high incidence of ankle sprains that occur later in matches suggests that fatigue may contribute to altered neuromuscular control of the ankle. Moreover, deficits in ankle joint position sense (JPS) were seen in patients with a history of recurrent ankle sprains. It has been hypothesized that ankle sprains may be related to altered ankle JPS as a consequence of fatigue.
Purpose: To evaluate if fatiguing contractions of evertor muscles alter the ankle JPS.
Study Design: Controlled laboratory study.
Methods: Thirty-six soccer players (age, 24.7 ¬± 1.3 years; height, 183.7 ¬± 8.2 cm; weight, 78.9 ¬± 7.9 kg) were recruited. Subjects were asked to recognize 2 positions (15¬? of inversion and maximal active inversion minus 5¬?) for 2 conditions: normal and fatigue. Muscular fatigue was induced in evertor muscles of the dominant leg by using isometric contractions. The average of the absolute and variable errors of 3 trials were recorded for both fatigue and nonfatigue conditions. A matched control group of 36 soccer players (age, 23.9 ¬± 0.9 years; height, 181.2 ¬± 6.9 cm; weight, 77.8 ¬± 6.5 kg) was asked to recognize the same positions, before a soccer match and after 45 minutes of playing, and their same scores were recorded. Finally, results of the 2 groups were compared.
Results: There was significant decrease in subjects’ ability to recognize passive and active repositioning of their ankle after a fatigue protocol (P < .001). Passive and active JPS were reduced after playing (P < .001). There was no significant difference between 2 groups in the results of JPS before and after the intervention (P > .1).
Conclusion: The acuity of the ankle JPS is reduced subsequent to a fatigue protocol and after a soccer match.
Background and objectives: The determination of the carbon isotope ratio in androgen metabolites has been previously shown to be a reliable, direct method to detect testosterone misuse in the context of antidoping testing. Here, we examine the variability in the 13C/12C ratios in urinary steroids in a widely heterogeneous cohort of professional soccer players residing in different countries (Argentina, Italy, Japan, South-Africa, Switzerland and Uganda).
Method: Carbon isotope ratios of selected androgens in urine specimens were determined using gas chromatography/combustion/isotope ratio mass spectrometry (GC-C-IRMS).
Results: Urinary steroids in Italian and Swiss populations were found to be enriched in 13C relative to other groups, reflecting higher consumption of C3 plants in these two countries. Importantly, detection criteria based on the difference in the carbon isotope ratio of androsterone and pregnanediol for each population were found to be well below the established threshold value for positive cases.
Conclusion: The results obtained with the tested diet groups highlight the importance of adapting the criteria if one wishes to increase the sensitivity of exogenous testosterone detection. In addition, confirmatory tests might be rendered more efficient by combining isotope ratio mass spectrometry with refined interpretation criteria for positivity and subject-based profiling of steroids.
The use of generic equations for estimating percent body fat from skinfold thicknesses can be criticised when applied to specific sports. The present aims were to compare existing methods of using skinfold data and to derive an equation for predicting body fat values in professional soccer players. Forty-five professional soccer players (24.2 +/- 5.0 years; 82.0 +/- 8.5 kg; 1.82 +/- 0.07 m) participated. Skinfold thicknesses were assessed at eight sites for the application of existing prediction equations. Skinfold data were also utilised to determine a novel soccer-specific equation. All players had a reference estimate of percent fat by dual-energy x-ray absorptiometry (DXA). The existing skinfold equations differed from the DXA-referenced values by varying degrees, the equation of Withers et al. (1987) demonstrating the lowest bias and highest relationship and agreement with DXA. Regression analysis resulted in an equation incorporating anterior thigh, abdominal, triceps and medial calf sites, accounting for 78.4% variance in DXA criterion values.
The aim of this study was to analyze the influence of individualized training (IT) on psychomotor performance of young soccer players. Psychomotor performance was measured by means of differential response time and number of correct responses to audio and visual stimuli. Kinematic analysis allowing assessment of both the distances and the average speeds of young players during consecutive matches was also performed. For the data analysis, one-way analysis of variance, Friedman test, and t-test for dependent samples were used. The obtained results clearly indicate that IT during the preparation period increases specific psychomotor performance among young soccer players.
Objective: Physical exercise is capable of enhancing or suppressing the immune response depending on the intensity and duration of exercise. This study investigated how exercise intensity influences the lymphocyte antioxidant response and the induction of cellular oxidative damage.
Design: Eighteen voluntary male pre-professional soccer players participated in this study. Sportsmen played a 60 min training match, and were divided into three groups depending on the intensity degree during the match: low, medium and high intensities.
Measurements: Malondialdehyde (MDA), vitamins C and E and haem oxygenase-1 (HO-1) gene expression were measured in lymphocytes. Reactive oxygen species (ROS) production was determined in lymphocytes and neutrophils.
Results: Lymphocyte MDA levels and H2O2 production were significantly increased in the group which performed the most intense exercise. Neutrophil counts and ROS production increased progressively with the exercise intensity. Vitamin C significantly decreased after exercise in the highest-intensity group in comparison with initial values, whereas vitamin E levels significantly increased in the medium and high-intensity groups. HO-1 gene expression significantly increased in the medium and high-intensity groups.
Conclusions: Exercise intensity affects the lymphocyte and neutrophil oxidant/antioxidant balance, but only exercise of high intensity induces lymphocyte oxidative damage.
AIM OF THE STUDY: Low back pain in soccer players is one of the frequently appearing disorders caused by overuse. Myogenic dysbalances are under discussion as possible reason for this problem. In the present study the muscular strength profile of the trunk musculature of soccer players with and without low back pain was evaluated. The results of the asymptomatic players were compared to those of players with low back pain; furthermore, the collected data were compared to those of an asymptomatic reference group. The question posed was whether soccer players show a specific strength profile caused by the special, sports-specific requirements and whether this strength profile differs between players with and without low back pain. METHOD: In the present study the isometric maximal strength of 18 soccer players with and 18 soccer players without low back pain was measured in all 3 planes. The reference group was provided by the Proxomed(R) company, which had previously analysed 1045 healthy untrained individuals of various age groups. RESULTS: The soccer players showed a sport-specific profile for the musculature, which was determined by a significant reduction of the flexion and rotation strength (flex: slashed circle 5.21 N/kg vs. slashed circle 6.49 N/kg; slashed circle 5.78 N/kg vs. slashed circle 6.66 N/kg respectively; rotation: left 7.09 N/kg, right 8.69 N/kg vs. left/right 10.1 N/kg; left 7.22 N/kg, right 8.24 N/kg vs. left/right 10.0 N/kg, respectively) as well as by an increased lateral flexion strength to the right-hand side in comparison to the reference group (lat. flex. right: 9.87 N/kg, respectively, 10.67 N/kg vs. 8.3 N/kg). A statistically significant correlation between the muscular activitiy in the trunk stability of soccer players with and without low back pain could not be shown. CONCLUSION: Obviously sports-specific training with additional specific training of the trunk muscles is not sufficient for the development of a balanced strength of trunk musculature. In the present study an influence of the performance of the trunk musculature on the incidence of low back pain could not be shown.
The aim of this study was to investigate the effects of fatigue induced by a field test representative of soccer specific movements on different hamstrings:quadriceps ratios in the dominant and non-dominant legs at two different velocities. Eight male football players (age: 21.3+/-2.3 years; height: 178+/-8 cm; body mass: 78+/-9 kg; playing level: British University Southern conference-3B) performed a pre-test to assess the concentric and eccentric strength of the hamstrings and the quadriceps at 60 degrees .s (-1) and 180 degrees .s (-1), The Loughborough Intermittent Shuttle Test (LIST) to simulate soccer, and a post-test similar to the pre-test. The main findings demonstrated significant decreases in the H (con):Q (con) ratio (calculated as the maximal concentric hamstrings strength divided by the maximal concentric quadriceps strength) in the dominant leg at 180 degrees .s (-1) and in the functional ratio H (ecc):Q (con) (calculated as the maximal eccentric hamstrings strength divided by the maximal concentric quadriceps strength) in the dominant leg at 60 degrees .s (-1) and 180 degrees .s (-1). In addition, significant correlations were observed between physiological parameters measured during the soccer-specific exercise and H (ecc):Q (con) only. These results suggested that the functional H (ecc):Q (con) ratio is more representative of fatigue induced by soccer than the conventional H (con):Q (con) ratio. Eccentric strength training at high velocities may be necessary to reduce injury risk in soccer players.
Background: The aerobic capacity of soccer players substantially influences their technical performance and tactical choices. Thus, the assessment of soccer players’ aerobic performance should be of interest for soccer coaches in order to evaluate and improve their endurance training sessions. In this study, we present a new test to assess aerobic performance in soccer by means of a specific dribbling track: the Hoff test. We further determined whether improvement in maximal oxygen uptake was reflected in increased distance covered in the Hoff test.
Methods: We tested 18 male soccer players (14 years old) both in the laboratory and using the Hoff test before and after 8 weeks of soccer training.
Results: The distance covered in the Hoff test correlated significantly with maximum oxygen uptake, and improved by 9.6% during the 8 week training period, while maximum oxygen uptake and running economy improved by 12 and 10%, respectively. Backward multiple regression showed maximum oxygen uptake to be the main explanatory variable for the distance covered in the Hoff test.
Conclusion: The present study demonstrated a significant correlation between laboratory testing of VO2max and performance in the Hoff test. Furthermore, training induced improvements in VO2max were reflected in improved performance in the Hoff test. We suggest that it should be a goal for active U-15 soccer players to cover more than 2100 metres in the Hoff test, as this requires a VO2max of above 200 ml/kg0.75/min, which should serve as a minimum in modern soccer.
In the present study, we aimed to compare the thermoregulatory response and soccer-specific training performance aspects of two commercially available sport drinks, both of similar carbohydrate concentration, but one containing 5.2% glycerol. Ten players participated in two similar outdoor training sessions and were randomly assigned to each of two drinks: a carbohydrate (C) beverage or a carbohydrate-glycerol (CG) beverage. Players consumed 500 mL of C or CG 30 minutes pre-exercise and at half-time. Pre- and postexercise body mass, core temperature (CT), and heart rate (HR) were recorded, and urine and blood samples were taken. No difference was observed between days for wet bulb globe temperature (session 1: 17.0 ¬± 1.1¬?C, session 2: 16.9 ¬± 1.1¬?C; P = 0.944). The degree of dehydration (% Œî BM) was greater after the C trial (P = 0.041). Similarly, percent change in plasma volume was greater in the C trial (P = 0.049). No overall main affect was observed between CT and mean exercise HRs during either training session (CT: P = 0.350; mean HR: P = 0.256), and there was no difference observed between groups in time to failure during the session-ending fatigue test (P = 0.547). Ingestion of a CG beverage provided players with better hydration than C alone. However, if training sessions are short (<75 minute), with adequate time for recovery, both drinks are sufficient for maintaining performance intensities during soccer-specific training.
The purpose of this study was to examine season-to-season
variations in physiological fitness parameters among a 1st team
squad of professional adult male soccer players for the confir-
matory purposes of identifying normative responses (immedi-
ately prior to pre-season training (PPS), mid-season (MID), and
end-of-season (EOS)). Test-retest data were collected from a
student population on the primary dependent variables of an-
aerobic threshold (AT) and maximal aerobic power (VO2 max)
to define meaningful measurement change in excess of test-
retest technical error between test-to-test performances. Partici-
pants from a pool of 42 professional soccer players were tested
over a set sequence of tests during the 3-year period: 1) basic
anthropometry, 2) countermovement jump (CMJ) tests 3) a
combined AT and VO2 max test. Over the 3-year period there
were no test-to-test changes in mean VO2 max performance
exceeding pre-defined limits of test agreement (mean of eight
measures: 61.6 ± 0.6 ml⋅kg-1⋅min-1). In contrast, VO2 at AT was
significantly higher at the MID test occasion in seasons 2
(+4.8%; p = 0.04, p < 0.05) and 3 (+6.8%; p = 0.03, p < 0.05).
The CMJ tests showed a test-to-test improvement of 6.3% (best
of 3 jumps) (p = 0.03, p < 0.05) and 10.3% (20-s sustained
jumping test) (p = 0.007, p < 0.01) between PPS2 and MID2 and
thereafter remained stable. Anthropometrics were unaffected. In
summary, despite some personnel changes in the elite cohort
between test-to-test occasions, VO2 max values did not vary
significantly over the study which supports previous short-term
observations suggesting a general ‘elite’ threshold of 60 ml⋅kg-
1‚ãÖmin. Interestingly, AT significantly varied where VO2 max
was stable and these variations also coincided with on- and off-
seasons suggesting that AT is a better indication of acute train-
ing state than VO2 max.
Background: Epidemiological findings of higher muscular thigh strain injury incidence during the latter stages of soccer match play have been attributed to fatigue.
Hypothesis: Soccer-specific fatigue will significantly reduce peak isokinetic torque of the knee flexors and extensors.
Study Design: Descriptive laboratory study.
Methods: Ten male professional soccer players (mean age, 24.7 ± 4.4 years; body mass, 77.1 ± 8.3 kg; maximum oxygen consumption [VO2 max], 63.0 ± 4.8 mL/kg/min) completed an intermittent treadmill protocol replicating the activity profile of match play. Before exercise and at 15-minute intervals, each player completed 1 of 2 randomized isokinetic dynamometer protocols. The first protocol quantified peak concentric knee extensor and flexor torque, while the second quantified peak concentric and eccentric knee flexor torque at isokinetic speeds of 180, 300, and 60 deg/s (3.14, 5.25, and 1.05 rad/s) with 5 repetitions at each speed.
Results: Concentric knee extensor and flexor peak torque were maintained throughout the duration of the exercise protocol, irrespective of movement speed. However, peak eccentric knee flexor torques at the end of the game (T300eccH105 = 127 ¬± 25 N¬?m) and at the end of the passive half-time interval (T300eccH60 = 133 ¬± 32 N¬?m) were significantly reduced relative to the first 15 minutes (T300eccH00 = 167 ¬± 35 N¬?m, P < .01; T300eccH15 = 161 ¬± 35 N¬?m, P = .02).
Conclusion: Eccentric knee flexor strength decreases as a function of time and after the half-time interval.
Clinical Relevance: This suggests a greater risk of injuries at these specific times, especially for explosive movements, in accord with epidemiological observations.
This study investigated the repeated-sprint ability (RSA) physiological responses to a standardized, high-intensity, intermittent running test (HIT), maximal oxygen uptake (VO2 max)<span class="absinlineequation"><img src="/cisti/journals/rp/gifs/h09-111ie1h.gif" /></span>s do not display in the abstract in HTML. For that reason, it is displayed as "V" here, but <span class="absinlineequation"><img src="/cisti/journals/rp/gifs/h09-111ie2h.gif" /></span> in the text., and oxygen uptake (VO2) kinetics in male soccer players (professional (N = 12) and amateur (N = 11)) of different playing standards. The relationships between each of these factors and RSA performance were determined. Mean RSA time (RSAmean) and RSA decrement were related to the physiological responses to HIT (blood lactate concentration ([La-]), r = 0.66 and 0.77; blood bicarbonate concentration ([HCO3-]), r = -0.71 and -0.75; and blood hydrogen ion concentration ([H+]),r = 0.61 and 0.73; all p < 0.05), VO2 max (r = -0.45 and -0.65, p < 0.05), and time constant () in VO2 kinetics (r = 0.62 and 0.62, p < 0.05). VO2 max was not different between playing standards (58.5 ¬± 4.0 vs. 56.3 ¬± 4.5 mL¬?kg-1¬?min-1; p = 0.227); however, the professional players demonstrated better RSAmean (7.17 ¬± 0.09 vs. 7.41 ¬± 0.19 s; p = 0.001), lower [La-] (5.7 ¬± 1.5 vs. 8.2 ¬± 2.2 mmol¬?L-1; p = 0.004), lower [H+] (46.5 ¬± 5.3 vs. 52.2 ¬± 3.4 mmol¬?L-1; p = 0.007), and higher [HCO3-] (20.1 ¬± 2.1 vs. 17.7 ¬± 1.7 mmol¬?L-1; p = 0.006) after the HIT, and a shorter in VO2 kinetics (27.2 ¬± 3.5 vs. 32.3 ¬± 6.0 s; p = 0.019).These results show that RSA performance, the physiological response to the HIT, and differentiate between professional- and amateur-standard soccer players. Our results also show that RSA performance is related to VO2 max, , and selected physiological responses to a standardized, high-intensity, intermittent exercise.
Soccer is a sport consisting of high-intensity intermittent exercise, with players making forays across their anaerobic threshold for tactical advantage followed by periods of recovery. The intensity and duration of these work and recovery bouts were defined during a men's soccer match using StepWatch Activity Monitors recording step rate for each 3-second period. The data were coded by custom software to separate work bouts (step rate >= 4) from recovery bouts (step rate < 4), and a square wave of the pattern of bouts was plotted for 5 players: center forward, central midfielder, wing midfielder, central defender, and wing defender. Four values were calculated for each work and recovery bout identified: duration, and mean, maximum, and minimum step rate (intensity). This novel technique provided detailed graphical information on the duration and exercise intensity of each position throughout the match. The center midfielder was able to sustain work and recovery bout characteristics throughout the match and appeared to recover at higher intensity levels than other players. The forward showed the consequence of accumulated fatigue late in the match and was unable to sustain the duration of high-intensity work bouts observed earlier in the match. The central defender attenuated the intensity of his work and recovery bouts late in the match staying closer to a more moderate work rate with fewer high- or low-intensity bouts. Having objective data qualifying players' work and recovery bout characteristics might prove valuable for tactical decision making, substitution timing, and for planning future training sessions.
The soccer-specific field tests are popular among coaches due to their simplicity, validity, and minimal use of equipment. Nevertheless, there is a general lack of data about their reliability, particularly regarding the tests of anaerobic performance. Twenty professional male soccer players performed 3 consecutive trials of the tests of throwing-in and standing-kick performance (the distance measured) as well as on timed 10-m sprint, flying 20-m sprint, running 10 ?ó 5 m, zigzag running with and without the ball, and the skill index (i.e., the ratio of the zigzag running without and with the ball). With the exception of the throwing-in and standing kick, the evaluated tests revealed high intraclass correlation coefficients (i.e., >0.80), small within-individual variations (coefficient of variation, <4%), and sample sizes for detecting a 2% change in the tested performance that are either close to or below the standard size of a professional soccer squad. In addition to simplicity and face validity, most of the evaluated tests revealed high reliability. Therefore, the evaluated tests are recommended for sport-specific profiling and early selection of young athletes as well as for routine testing procedures that could detect effects of various intervention procedures. Regarding the throwing-in and standing-kick tests, direct measurement of the ball velocity (e.g., with a standard radar gun) is recommended.
Soccer shoes in general but especially their outsoles are important for running and consequently playing performance. This article aims to quantify running performance and perception of running performance due to type of footwear and surface condition by use of Functional Traction Courses (FTC). Soccer players were required to run through slalom and acceleration courses as fast as possible providing running time and perception of running time variables due to wearing different soccer footwear. A series of eight single studies featuring different types of soccer footwear and different surfaces was conducted. The influence of footwear (subject Means and SD) was analyzed by Repeated Measures ANOVA, followed by post-hoc t-tests when appropriate. Slalom running times were considerably affected by altered shoe/surface interface conditions, whereas acceleration running times were affected only to lesser extent. Running time perception of athletes generally reflected actual running performance. Running performance differed about 3% when altering stud type or stud geometry. Thus, players benefit by the appropriate choice of footwear for a given surface. Complete elimination of studs resulted in a running time difference of 26% compared to normal condition. Surface conditions may be responsible for up to 20% of performance differences. It is recommended to include FTC testing in the evaluation of soccer footwear to get an idea of potential running performance benefits for players.
BACKGROUND: The association between the lipid profiles level and the incidence and severity of coronary heart disease
(CHD) is very pronounced in epidemiological studies, and an inverse relation between physical fitness and the inci-
dence of coronary heart disease has been observed in many studies. The aim of this study was to investigate the impact
of a soccer match on lipid parameters of professional soccer players.
METHODS: Twenty two professional soccer players participated in the study. Blood (10ml) for determination of lipid
profiles was obtained at rest and immediately after a 90 minute soccer match. Lipid parameters were measured using
Boehringer Mannheim kits and Clinilab and BioMerieux analyser.
RESULTS: The results of this study showed that the triglyceride was significantly higher before the match than after-
wards (159.09 ± 58.2 vs. 88.63 ± 34.1 mg/dl, p < 0.001), whereas the low-density lipoprotein (LDL) was lower before
the match than after it (98.04 ± 28.9 vs. 112.31 ± 30.5 mg/dl). Moreover, there were no significant differences in cho-
lesterol concentration (171.4 ± 30.28 mg/dl vs. 173.18 ± 32.75 mg/dl) and high-density lipoprotein (HDL) concentra-
tion (34.04 ± 5.58 mg/dl vs. 34.4 ± 4.6 mg/dl) between before and after the match.
CONCLUSIONS: Although the soccer competitive match has no favourable acute effect on lipid profiles, the lower rate of
LDL, cholesterol and triglyceride as well as the higher level of HDL in players suggest a beneficial effect of regular
soccer training on arthrosclerosis and perhaps on CHD risk as well
The purpose of the study was to determine the influence of preseason lower-extremity range of motion (ROM) on the risk of muscle strain injury during a competitive season for elite soccer players. Thirty-six elite male soccer players (age, 25.6 = 4.7 years) had maximum static ROM for 6 movements of the lower extremity measured prior to the 2003-2004 English Premier League season. Player age, body size, dominant limb, and playing position were documented also. All lower-extremity muscle strain injuries were recorded prospectively during the competitive season, as was the total amount of time spent in training and games for each player.Soccer players sustaining a muscle strain injury in the hip flexors or knee flexors had lower pre- season ROM (p <= 0.05) in these muscle groups compared with uninjured players. Similar trends were observed for the remaining muscle groups, but all failed to reach statistical significance (p >= 0.05). Most significantly, soccer players with lower preseason ROM in the hip flexors and knee flexors had a statistically higher risk for a muscle strain injury to these muscle groups during a competitive season. Age, body size, limb dominance, and playing position were not significant intrinsic risk factors for the development of muscle strain injuries. Screening of flexibility for soccer players should be conducted during preseason, and flexibility training should be prescribed to players with reduced ROM to lower the risk of developing a muscle strain injury.
The main aim of the present study was to investigate the effects of soccer-specific training on physical fitness components in adolescent elite soccer players and make comparisons with older counterparts. Twenty two male soccer players from the Serbian First Division team were allocated to two assigned trials according to age – young group (YG) and mature group (MG). Players in their teenage years (19 years and younger) were assigned to YG (10 subjects) and others to MG (12 subjects). Between the first and second test session, all subjects followed six weeks of soccer-specific periodized training programme. There were no differences between groups at pre- and post-training trial for body mass, vertical jump height, average anaerobic power and VO2max (P>0.05). Body fat was significantly lower in YG before and after training program as compared to MG (P<0.05). Body mass and fat dropped significantly in both groups after training program (P<0.05). Furthermore, average anaerobic power and VO2max along with vertical jump height, were significantly improved in both groups (P<0.05) at post-training performance. Finally, the magnitude of change in VO2max was significanty superior in MG as compared to YG after training program (18.3 vs. 7.8%; P<0.05). The findings of the present study indicate that the trainability indices are not highly influenced by age in top-level soccer players.
The aim of the present study was to compare the physiologic impact of intermittent exercise in specific shuttle running (IS), which requires 180[degrees] directional changes, and traditional in-line (IL) running. Ten elite male adult soccer players performed different intermittent exercises according to their maximal aerobic velocity ([nu][latin capital V with dot above]O2max): 30-30 seconds at 100% (30 s of runs at 100% of [nu][latin capital V with dot above]O2max alternated with 30-s recovery period), 105%, and 110% of [nu][latin capital V with dot above]O2max with active recovery, 15-15 seconds at 105%, 110%, and 115% of [nu][latin capital V with dot above]O2max, and 10-10 seconds at 110%, 115%, and 120% of [nu][latin capital V with dot above]O2max with passive recovery. Each exercise was performed in the IL and IS format in a randomized order. Heart rate (HR) expressed in percentage of HR reserve (HRres), postexercise blood lactate concentration [La], and ratings of perceived exertion (RPE) were recorded. The different 30-30 seconds showed significantly higher HRres responses in IS compared with IL (p < 0.01). The [La] and RPE results indicated higher values in IS. In conclusion, the physiologic impact of specific IS is substantially higher than in traditional IL. The changes of direction induce an increase in the anaerobic metabolism solicitation and consequently create different responses compared with traditional IL running. This information can aid coaches in the design of intermittent training programs using classical (IL) or a specific form (IS) of running to induce different physiologic responses.
The purpose of the study was to examine the relationships among aerobic fitness, anaerobic capacity, and performance indices of 2 different repeated sprint test (RST) protocols in a group of 33 elite adolescent soccer players (age range 16-18 years). All participants performed 4 tests: an aerobic power test (20-m shuttle run), the Wingate Anaerobic Test (WAnT), and 2 different RST protocols (12 ?ó 20 and 6 ?ó 40 m). Significant correlations (p < 0.05) were found between the fastest sprint (r = 0.618), total sprint time (r = 0.709), and performance decrement (PD; r = 0.411) of the 2 RST protocols. A significant negative correlation was found between the PD in the 12 ?ó 20-m RST and calculated peak VÃáo2 (r = -0.60, p < 0.05). There was no significant correlation between PD of the 6 ?ó 40-m RST and calculated peak VÃáo2 (r = -0.32, p = 0.09). The mean power in the WAnT was significantly correlated with the fastest sprint and the total sprint time of the 6 ?ó 40-m protocol (r = -0.42 and -0.45, respectively) and with the total sprint time of the 12 ?ó 20-m protocol (r = -0.47). There were no correlations between other indices of the WAnT and the 2 RSTs. Despite identical total work, different RST protocols represent different physiological implications. The aerobic system plays a significant role in the maintenance of intensity level during a soccer game, which is characterized by short bursts of activities. Anaerobic performance of repeated brief efforts imposes different physiological stress than a single prolonged activity and, thus, may reflect different physiological capabilities. Therefore, anaerobic testing procedures should consist of specific protocols that mimic the athlete's specific sports activity pattern.
This study examined the effect of caffeine supplementation on the white cell count and muscle damage marker responses to intermittent-interval exercise as performed by soccer players. Subjects (n = 20) completed a placebo-controlled double-blind test protocol. Forty-five minutes before exercise, participants ingested 4.5 mg¬?kg‚àí1 body mass of caffeine (EXP) or placebo (CONT). Blood samples were collected before and after exercise to measure hematological parameters, serum creatine kinase (CK), lactate dehydrogenase (LDH), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AP) and Œ?-glutamyl transferase (Œ?-GT) activity. To compare differences among all variables, 2 (time) ?ó 2 (group) repeated measures ANOVA (with Tukey's post hoc tests) was conducted. Exercise caused leukocytosis (38.5% and 36.1%in EXP and CONT, respectively), lymphocytosis (42.1%and 44.9%; p < 0.05) and neutrophilia (38.2% and 31.5%; p < 0.05) without an additional effect due to caffeine (p > 0.05). Also, serum CK and LDH activity were enhanced by exercise in both groups (p < 0.05), without a synergistic effect of caffeine. ALT, AST, AP and Œ?-GT serum activity was not modulated by exercise or caffeine. The findings demonstrate that white cells and muscle damage markers increase after intense intermittent exercise, but acute caffeine supplementation has no influence on immune responses or muscle cellular integrity.
Tegtbur et al. [23] devised a new method able to estimate the intensity at maximal lactate steady state termed “lactate minimum test. According to Billat et al. [7], no studies have yet been published on the affect of training on highest blood lactate concentration that can be maintained over time without continual blood lactate accumulation. Therefore, the aim of the present study was to verify the effect of soccer training on the running speed and the blood lactate concentration (BLC) at the lactate minimum test (Lacmin). Thirteen Brazilian male professional soccer players, all members of the same team playing at National level, volunteered for this study. Measurements were carried out before (pre) and after (post) eight weeks of soccer training. The Lacmin test was adapted to the procedures reported by Tegtbur et al. [23]. The running speed at the Lacmin test was taken when the gradient of the line was zero. Differences in running speed and blood lactate concentration at the Lacmin test before (pre) and after (post) the training program were evaluated by Student’s paired t-test. The training program increased the running speed at the Lacmin test (14.94±0.21 vs. 15.44±0.42* km•h-1) and the blood lactate concentration (5.11±2.31 vs. 6.93±1.33* mmol•L-1). The enhance in the blood lactate concentration may be explained by an increase in the lactate/H+ transport capacity of human skeletal muscle verified by other authors.
The purpose of this study was to examine the relationships between shot valence, avoidance behavior, and performance in soccer penalty shootouts. Video analyses were conducted with all penalty shootouts ever held in the World Cup, the European Championships, and the UEFA Champions League (n = 36 shootouts, 359 kicks). Shot valence was assessed from the potential consequences of a shot outcome as follows: Shots where a goal instantly leads to victory were classified as positive valence shots and shots where a miss instantly leads to loss as negative valence shots. Avoidance behavior was defined as looking away from the goalkeeper or preparing the shot quickly (thus speeding up the wait). The results showed that avoidance behavior occurred more with negative valence shots than with positive shots and that players with negative valence shots performed worse than those with positive shots. Thus, avoidance motivation may help explain why professional athletes occasionally choke under pressure.
Most soccer players have a favoured foot for kicking the ball, and it is believed that this preference may lead to an asymmetry in the strength and flexibility of the lower extremities. This study was designed to determine whether asymmetry in strength and flexibility are present in the legs of soccer players. Forty-one elite and sub-elite soccer players (age 23.4 ± 3.8 years; height 1.81 ± 0.06 m; body mass 81.7 ± 9.9 kg) were studied (data are presented as mean ± SD). The dynamic strength of knee flexors (hamstrings) and knee extensors (quadriceps) was measured using an isokinetic dynamometer at angular velocities of 1.05, 2.09, 5.23 rad/s (in a concentric mode) and 2.09 rad/s (in an eccentric mode). The concentric strength ratio (hamstrings conc /quadriceps conc ) and the dynamic control ratio (hamstrings ecc /quadriceps conc ) were computed. Hip joint flexibility (in flexion) was measured using a goniometer. A significant difference between the preferred and non-preferred leg was found in the knee flexors at 2.09 rad/s (119 ± 22 versus 126 ± 24 Nm; P 10%) in one or more specific muscle groups. No significant differences were found in flexibility of the hip joint between the preferred and non-preferred leg ( P > 0.05). It is concluded that the lower strength of the knee flexor muscles of the preferred leg may be associated with the differential use of these muscle during the kicking action and thus constitutes a unique training effect associated with soccer. This in turn can lead to muscular imbalance which is generally regarded as an injury risk factor.
The purpose of this study was to describe the physical fitness of professional soccer players in South Africa and assess the difference in fitness status between different playing positions. Professional soccer players (N = 140) from various clubs in the Premier Soccer League (PSL) in South Africa underwent a battery of tests assessing key physiological components during the first half of their competitive season. Players were separated into one of four primary playing positions (goalkeepers, GK, n = 16; defenders, DEF, n = 48; midfielders, MID, n = 46; forwards, FWD, n = 30) on the basis of their playing position and designated role within the team. Descriptive statistics (mean + SD) were calculated for the entire group and each position, and a one-way ANOVA was used to compare the positions for each of the physical tests. No differences were found between positions in age, flexibility, absolute vertical jump height, strength-endurance, acceleration and speed, or agility.
The aim of this study was to examine the relationship of 2 different field tests for the assessment of aerobic fitness in soccer players with the multistage 20-m test used for the evaluation of maximum oxygen uptake. Nineteen semi-professional male soccer players (age: 22.8 +/- 2.5 mean +/- SD) performed, under similar conditions, 3 field tests in a counterbalanced order 7 days apart. These tests were the multistage 20-m shuttle run test (MSRT), the Bangsbo test, and the Hoff test. Heart rate was recorded in all tests with telemetry, and the Borg scale was introduced at the end of exercise. Finally, 3-minute post-test lactate concentration was determined. Performance was 11.2 +/- 0.9 levels in the MSRT, 1,658.9 +/- 119.9 m in the Bangsbo test, and 1,798.2 +/- 125.9 m in the Hoff test. There was a significant correlation between the Hoff test and performance in the MSRT (r = 0.49, p < 0.05). The Bangsbo test was not associated with the MSRT score (r = 0.26, p > 0.05). The maximum heart rate achieved in the Bangsbo test was significantly lower compared with that in the MSRT and Hoff test (Bangsbo: 186.6 +/- 9.6, Hoff: 192 +/- 7.6, MSRT: 190.4 +/- 9.3 beats/min, p < 0.05). No difference was found in post-test lactate concentration among the 3 tests. In conclusion, the Hoff test can be used for the assessment of endurance in adult semi-professional soccer players. Coaches and teams could benefit from using the Hoff test that resembles soccer actions for the assessment of players' aerobic fitness.
We determined the genotype and allelic frequency of several genetic polymorphisms (ACE I/D, GDF-8 K153R [and also E164 K, P198A and I225 T] and AMPD1 C34 T) that are candidates to influence sports performance in a group of 54 male professional soccer players. Their results were compared with those of elite endurance male athletes (52 runners) and 123 sedentary, healthy men (controls). We found statistical significance for the ACE ID (χ2(2)=8.176, P=0.017) and II genotypes (χ2(2)=16.137, P<0.001) with a higher and lower frequency of ID (P=0.005) and II (P<0.001), respectively, in soccer players than in endurance runners. Statistical significance was also reached for AMPD1 (with a higher frequency of the CT genotype in soccer players than in runners [χ2(2)=7.538, P=0.006]) but not for GDF-8 K153R. Since the ACE II genotype is associated with improved potential for endurance performance but with decreased training gains in muscle mass and strength, these findings together with previous results [37] support the notion that elite soccer players tend to have a power/strength oriented genotype.
The purpose of this study was: 1) to collect baseline data on nutrient intake in order to advise athletes about nu-
trition practices that might enhance performance, and 2) to evaluate the dietary iron intake and blood iron status
of Japanese collegiate soccer players. The subjects were 31 soccer players and 15 controls. Dietary information
was obtained with a food frequency questionnaire. The mean carbohydrate (6.9 gÔ?•kg-1 BW) and protein (1.3
g/kg) intakes of the soccer players were marginal in comparisons with recommended targets. The mean intakes
of calcium, magnesium, vitamin A, B1, B2, and C were lower than the respective Japanese recommended dietary
allowances (RDAs) or adequate dietary intakes in the soccer players. The mean intakes of green and other vege-
tables, milk and dairy products, fruits, and eggs were lower than the recommended targets. Thus, we recom-
mended athletes to increase the intake of these foodstuffs along with slight increase in carbohydrate and lean
meat. The mean intake of iron was higher than the respective RDA in the soccer players. A high prevalence of
hemolysis (71%) in the soccer players was found. None of the soccer players and controls had anemia. Two soc-
cer players had iron depletion, while none was found in the controls. In those players who had iron deficiency,
the training load need to be lowered and/or iron intake may be increased
The aim of the present investigation was to provide a detailed analysis of the high intensity running activity completed by elite soccer players during match-play. A further aim of the study was to evaluate the importance of high intensity running activity to overall team success. Observations on individual match performance measures were undertaken on 563 outfield players (median of 8 games per player; range=1-57) competing in the English Premier League from 2003/2004 to 2005/2006 using a computerised tracking system (Prozone®, Leeds, England). High intensity activities selected for analysis included total high intensity running distance (THIR), total sprint distance (TSD) and the number and type of sprints undertaken. Total high intensity running distance in possession and without possession of the ball was also analysed. The THIR was dependant upon playing position with wide midfield (1 049±106 m) and central defenders (681±128 m) completing the highest and lowest distance respectively (p<0.001). High intensity activity was also related to team success with teams finishing in the bottom five (919±128 m) and middle ten (917±143 m) league positions completing significantly more THIR compared with teams in the top five (885±113 m) (p=0.003). The THIR and TSD also significantly declined during the 2nd half with the greatest decrements observed in wide midfield and attacking players (p<0.05). Both positional differences in high intensity activity and the observed change in activity throughout the game were also influenced by team success (p<0.05). The results of the present study indicate that high intensity activity in elite soccer match-play is influenced by both playing position and previous activity in the game. These activity patterns are also dependant upon success of the team. This may indicate that overall technical and tactical effectiveness of the team rather than high levels of physical performance per se are more important in determining success in soccer.
Abstract The purpose of this study is to identify lower-extremity (LE) musculoskeletal characteristics of elite female soccer players and to determine whether differences between dominant and nondominant extremities exist with respect to strength, flexibility, and range of motion. Physical data were collected from 26 female professional soccer players. Core control, hip and knee passive range of motion (PROM), LE flexibility, hip abductor strength, and dynamic functional alignment were assessed for each LE. Of 26 subjects, 21 scored 2/5 or less on core control. Mean hip internal rotation and external rotation were 33¬? (¬±8¬?) and 25¬? (¬±6.7¬?), respectively. All subjects had shortened two-joint hip flexors with an average knee flexion angle of 50¬? (¬±11¬?) and increased femoral anteversion. Forty one of 48 dominant limbs and 42 of 48 nondominant limbs demonstrated deviations from neutral alignment during step down or single-leg squat. Of 25 subjects, 15 demonstrated a stiff-knee landing and/or takeoff. All subjects demonstrated limitations in hip external rotation PROM and hip flexor length. There was no difference between dominant and nondominant LEs in all variables including hip abductor strength. Additional research is needed to determine if there is a correlation between the musculoskeletal characteristics, LE biomechanics, and potential risk for injury.
The aim of the present study was to examine how explosive strength, kicking speed, and body composition are affected by a 12-week plyometric training program in elite female soccer players. The hypothesis was that this program would increase the jumping ability and kicking speed and that these gains could be maintained by means of regular soccer training only. Twenty adult female players were divided into 2 groups: control group (CG, n = 10, age 23.0 ¬± 3.2 yr) and plyometric group (PG, n = 10; age 22.8 ¬± 2.1 yr). The intervention was carried out during the second part of the competitive season. Both groups performed technical and tactical training exercises and matches together. However, the CG followed the regular soccer physical conditioning program, which was replaced by a plyometric program for PG. Neither CG nor PG performed weight training. Plyometric training took place 3 days a week for 12 weeks including jumps over hurdles, drop jumps (DJ) in stands, or horizontal jumps. Body mass, body composition, countermovement jump height, DJ height, and kicking speed were measured on 4 separate occasions. The PG demonstrated significant increases (p < 0.05) in jumping ability after 6 weeks of training and in kicking speed after 12 weeks. There were no significant time ?ó group interaction effects for body composition. It could be concluded that a 12-week plyometric program can improve explosive strength in female soccer players and that these improvements can be transferred to soccer kick performance in terms of ball speed. However, players need time to transfer these improvements in strength to the specific task. Regular soccer training can maintain the improvements from a plyometric training program for several weeks.
In many animal species including humans circulating androgen levels in males respond to social challenges. This response has been interpreted as an adaptive mechanism that helps the individuals to adjust their behavior to changes in social context. According to this hypothesis socially modulated androgen levels (e.g. increased levels in dominants and decreased levels in subordinates) would influence the subsequent expression of social behavior in a status-dependent fashion. This rationale is partially based on male physiology and therefore has been rarely investigated in females. Here, we investigated if a hormonal response to a social challenge that produces changes in status is also present in human females. We have collected saliva from and administered questionnaires to female soccer players of both teams playing the final match of the Portuguese Female soccer league. Samples were collected on a neutral day and on the day of the game both before and after the match. The change in testosterone levels (i.e. post-game − pre-game values = ΔT) was positive in the winners and negative in the losers and there was a significant difference in the testosterone change (i.e. ΔT) over the game between winners and losers. Cortisol levels did not vary with contest outcome. An anticipatory rise in circulating levels of both hormones (testosterone and cortisol) was detected before the match. Paralleling the hormonal responses, changes in mood and anxiety state were also found between both teams, with more positive states being observed in winners and more negative states being observed in losers at the end of the match. These results suggest that testosterone also responds to social challenges in human females and that contest-induced mood changes may influence this response.
This study examined the relative contribution of visual, perceptual, and cognitive skills to the development of expertise in soccer. 137 elite and sub-elite players (aged 9-17 yrs) were assessed using a multidimensional battery of tests. Four aspects of visual function were measured: static and dynamic visual acuity; stereoscopic depth sensitivity; and peripheral awareness. Perceptual and cognitive skills were assessed via the use of situational probabilities, as well as tests of anticipation and memory recall. Stepwise discriminant analyses revealed that the tests of visual function did not consistently discriminate between skill groups at any age. Tests of anticipatory performance and use of situational probabilities were the best in discriminating across skill groups. Memory recall of structured patterns of play was most predictive of age. As early as age 9, elite soccer players demonstrated superior perceptual and cognitive skills when compared to their sub-elite counterparts. Implications for training perceptual and cognitive skill in sport are discussed.
The aim of this study was to determine the validity and reliability of a 90-minute soccer performance test: Ball-sport Endurance and Sprint Test (BEAST90). Fifteen healthy male amateur soccer players participated and attended 5 testing sessions over a 10-day period to perform physiologic and soccer-specific assessments. This included familiarization sessions and 2 full trials of the BEAST90, separated by 7 days. The total 90-minute distance, mean percent peak heart rate (HRpeak), and estimated percent peak oxygen uptake of the BEAST90 were 8,097 +/- 458 m, 85 +/- 5% and 82 +/- 14%, respectively. Measures obtained from trial 1 and trial 2 were not significantly different (p > 0.05). Reliability of measures over 90 minutes ranged from 0.9-25.5% (% typical error). The BEAST90 protocol replicated soccer match play in terms of time, movement patterns, physical demands (volume and intensity), distances, and mean and HRpeak values, as well as having an aerobic load similar to that observed during a soccer match. Reproducibility of key physical measures during the BEAST90 were mostly high, suggesting good reliability. The BEAST90 could be used in studies that wish to determine the effects of training or nutritional interventions on prolonged intermittent physical performance.
The purpose of this study was to evaluate the maximal oxygen uptake (VO2max) values in soccer players as assessed by field and laboratory tests. Thirty-five elite young soccer players were studied (mean age 18.1 +/- 1.0 years, training duration 8.3 +/- 1.5 years) in the middle of the playing season. All subjects performed 2 maximal field tests: the Yo-Yo endurance test (T1) for the estimation of VO2max according to normogram values, and the Yo-Yo intermittent endurance test (T2) using portable telemetric ergospirometry; as well as 2 maximal exercise tests on the treadmill with continuous (T3) and intermittent (T4) protocols. The estimated VO2max values of the T1 test (56.33 ml[middle dot]kg-1[middle dot]min-1) were 10.5%, 11.4%, and 13.3% (p <= 0.05) lower than those of the T2 (62.96 ml[middle dot]kg-1[middle dot]min-1), T3(63.59 ml[middle dot]kg-1[middle dot]min-1) and T4 (64.98 ml[middle dot]kg-1[middle dot]min-1) tests, respectively. Significant differences were also found between the intermittent exercise protocols T1 and T3 (p <= 0.001) and the continuous exercise protocols T2 and T4 (p <= 0.001). There was a high degree of cross correlation between the VO2max values of the 3 ergospirometric tests (T2 versus T3, r = 0.47, p <= 0.005; T2versus T4, r = 0.59, p <= 0.001; T3 versus T4 r = 0.79, p <= 0.001). It is necessary to use ergospirometry to accurately estimate aerobic capacity in soccer players. Nevertheless, the Yo-Yo field tests should be used by coaches because they are easy and helpful tools in the training program setting and for player follow-up during the playing season.
Abstract Proprioceptive training has been shown to reduce the incidence of ankle sprains in different sports. It can also improve rehabilitation after anterior cruciate ligament (ACL) injuries whether treated operatively or nonoperatively. Since ACL injuries lead to long absence from sports and are one of the main causes of permanent sports disability, it is essential to try to prevent them. In a prospective controlled study of 600 soccer players in 40 semiprofessional or amateur teams, we studied the possible preventive effect of a gradually increasing proprioceptive training on four different types of wobble-boards during three soccer seasons. Three hundred players were instructed to train 20 min per day with 5 different phases of increasing difficulty. The first phase consisted of balance training without any balance board; phase 2 of training on a rectangular balance board; phase 3 of training on a round board; phase 4 of training on a combined round and rectangular board; phase 5 of training on a so-called BABS board. A control group of 300 players from other, comparable teams trained ldquonormallyrdquo and received no special balance training. Both groups were observed for three whole soccer seasons, and possible ACL lesions were diagnosed by clinical examination, KT-1000 measurements, magnetic resonance imaging or computed tomography, and arthroscopy. We found an incidence of 1.15 ACL injuries per team per year in the control group and 0.15 injuries per team per year in the proprioceptively trained group (P<0.001). Proprioceptive training can thus significantly reduce the incidence of ACL injuries in soccer players.
Soccer is characterised as a high intensity, intermittent non-continuous exercise. Players cover approximately 10 km of ground per game, of which 8 to 18% is at the highest individual speed. In higher levels of competition there is a greater number of tackles and headings plus a greater percentage of the game is performed at maximum speed. The average aerobic energy yield during a national level game is around 80% of the individual maximum. Blood lactate concentration during a game averages 7 to 8 mmol/L. Because of a high energy yield most players have empty muscle glycogen stores at the end of the game, were hypohydrated and also have an increased body temperature. Soccer players of national and international standard have a maximal aerobic power of around 60 to 65 ml/kg/min, an above average anaerobic alactacid power, and a greater buffer capacity and muscle strength compared with untrained controls, yet seem to be less flexible.
This review considers the biomechanical factors that are relevant to success in the game of soccer. Three broad areas are covered: (1) the technical performance of soccer skills; (2) the equipment used in playing the game; and (3) the causative mechanisms of specific soccer injuries. Kicking is the most widely studied soccer skill. Although there are many types of kick, the variant most widely reported in the literature is the maximum velocity instep kick of a stationary ball. In contrast, several other skills, such as throwing-in and goalkeeping, have received little attention; some, for example passing and trapping the ball, tackling, falling behaviour, jumping, running, sprinting, starting, stopping and changing direction, have not been the subject of any detailed biomechanical investigation. The items of equipment reviewed are boots, the ball, artificial and natural turf surfaces and shin guards. Little of the research conducted by equipment manufacturers is in the public domain; this part of the review therefore concentrates on the mechanical responses of equipment, player-equipment interaction, and the eff ects of equipment on player performance and protection. Although the equipment has mechanical characteristics that can be reasonably well quantified, the player-equipment interaction is more difficult to establish; this makes its efficacy for performance or protection difficult to predict. Some soccer injuries may be attributable to the equipment used. The soccer boot has a poor protective capability, but careful design can have a minor influence on reducing the severity of ankle inversion injuries. Performance requirements limit the scope for reducing these injuries; alternative methods for providing ankle stability are necessary. Artificial surfaces result in injury profiles diff erent from those on natural turf pitches. There is a tendency for fewer serious injuries, but more minor injuries, on artificial turf than on natural turf pitches. Players adapt to surface types over a period of several games. Therefore, changing from one surface to another is a major aetiological factor in surface-related injuries. Heading the ball could lead to long-term brain damage. Simulation studies suggest the importance of ball mass, ball speed and player mass in affecting the severity of impact. Careful instruction and skill development, together with the correct equipment, is necessary for young players. Most applications of biomechanical techniques to soccer have been descriptive experimental studies. Biomechanical modelling techniques have helped in the understanding of the underlying mechanisms of performance, although their use has been limited. It is concluded that there are still many features of the game of soccer that are amenable to biomechanical treatment, and many opportunities for biomechanists to make a contribution to the science of soccer.
This study investigated the relationship between exposure time and ankle sprains in soccer. Forty-one teams (639 players) from four male senior soccer divisions at different levels of skill (divisions I-VI) were followed prospectively for 1 year. The exposure to soccer and the number of injuries per player were higher in higher divisions, but the injury incidence, percentage of ankle injuries and incidence of ankle injuries were the same at different levels of skill. Of all injuries 17 to 20% were ankle sprains and the incidence varied between 1.7 to 2.0 ankle injuries per 1,000 hours of exposure. Since players with previous ankle problems run an increased risk of reinjury we suggest that these players receive preventive advice.
In elite outfield players, the average work rate during a soccer match, as estimated from variables such as heart rate, is approximately 70% of maximal oxygen uptake (VO2 max). This corresponds to an energy production of approximately 5700 kJ (1360 kcal) for a person weighing 75 kg with a VO2 max of 60 ml kg-1 min-1. Aerobic energy production appears to account for more than 90% of total energy consumption. Nevertheless, anaerobic energy production plays an essential role during soccer matches. During intensive exercise periods of a game, creatine phosphate, and to a lesser extent the stored adenosine triphosphate, are utilized. Both compounds are partly restored during a subsequent prolonged rest period. In blood samples taken after top-class soccer matches, the lactate concentration averages 3-9 mM, and individual values frequently exceed 10 mM during match-play. Furthermore, the adenosine diphosphate degradation products--ammonia/ammonium, hypoxanthine and uric acid--are elevated in the blood during soccer matches. Thus, the anaerobic energy systems are heavily taxes during periods of match-play. Glycogen in the working muscle seems to be the most important substrate for energy production during soccer matches. However, muscle triglycerides, blood free fatty acids and glucose are also used as substrates for oxidative metabolism in the muscles.
Purpose: The aim of the present study was to study the effects of aerobic training on performance during soccer match and soccer specific tests.
Methods: Nineteen male elite junior soccer players, age 18.1 ± 0.8 yr, randomly assigned to the training group (N = 9) and the control group (N = 10) participated in the study. The specific aerobic training consisted of interval training, four times 4 min at 90-95% of maximal heart rate, with a 3-min jog in between, twice per week for 8 wk. Players were monitored by video during two matches, one before and one after training.
Results: In the training group: a) maximal oxygen uptake (VÃáO2max) increased from 58.1 ¬± 4.5 mL¬?kg-1¬?min-1 to 64.3 ¬± 3.9 mL¬?kg-1¬?min-1 (P < 0.01); b) lactate threshold improved from 47.8 ¬± 5.3 mL¬?kg-1¬?min-1 to 55.4 ¬± 4.1 mL¬?kg-1¬?min-1 (P < 0.01); c) running economy was also improved by 6.7% (P < 0.05); d) distance covered during a match increased by 20% in the training group (P < 0.01); e) number of sprints increased by 100% (P < 0.01); f) number of involvements with the ball increased by 24% (P < 0.05); g) the average work intensity during a soccer match, measured as percent of maximal heart rate, was enhanced from 82.7 ¬± 3.4% to 85.6 ¬± 3.1% (P < 0.05); and h) no changes were found in maximal vertical jumping height, strength, speed, kicking velocity, kicking precision, or quality of passes after the training period. The control group showed no changes in any of the tested parameters.
Conclusion: Enhanced aerobic endurance in soccer players improved soccer performance by increasing the distance covered, enhancing work intensity, and increasing the number of sprints and involvements with the ball during a match.
This review is focused on anthropometric and physiological characteristics of soccer players with a view to establishing their roles within talent detection, identification and development programmes. Top-class soccer playershave to adapt to the physical demandsof the game, which are multifactorial. Players may not need to have an extraordinary capacity within any of the areas of physical performance but must possess a reasonably high level within all areas. This explains why there are marked individual differences in anthropometric and physiological characteristics among top players. Various measurements have been used to evaluate specific aspects of the physical performance of both youth and adult soccer players.The positional role of a player is related to his or her physiological capacity. Thus, midfield players and full-backs have the highest maximal oxygen intakes (> 60 ml¬?kg-1¬?min-1) and perform best in intermittent exercise tests. On the other hand, midfield players tend to have the lowest muscle strength. Although these distinctions are evident in adult and elite youth players, their existence must be interpreted circumspectly in talent identification and development programmes. A range of relevant anthropometric and physiological factors can be considered which are subject to strong genetic influences (e.g. stature and maximal oxygen intake) or are largely environmentally determined and susceptible to training effects. Consequently, fitness profiling can generate a useful database against which talented groups may be compared. No single method allows for a representative assessment of a player"s physical capabilities for soccer. Weconclude that anthropometric and physiological criteria do have a role as part of a holistic monitoring of talented young players.
Purpose: The major purpose of the present study was to examine whether there exists a relationship between preseasonal physiological tests and performance results in the soccer league. Further, it investigated maximal oxygen uptake and maximal strength in proportion to body mass for soccer players. A secondary aim was to establish some normative data of Norwegian elite soccer players.
Methods: Two teams from the Norwegian elite soccer league participated in the study.
Results/Conclusion: The present study supports previous investigations indicating a positive relationship between maximal aerobic capacity, physical strength, and performance results in the elite soccer league. It is concluded that for soccer players, maximal oxygen uptake should be expressed in relation to body mass raised to the power of 0.75 and maximal strength in relation to body mass raised to the power of 0.67, when the aim is to evaluate maximal aerobic capacity when running and strength capacity among players with different body mass. Midfield players had significantly higher maximal oxygen uptake compared with defense players using the traditional expression, mL¬?kg-1¬?min-1, while no significant differences were found expressing maximal oxygen uptake either absolutely(L¬?min-1) or in relation to body mass raised to the power of 0.75 (mL¬?kg-0.75¬?min-1) among players grouped by position. There was a significant correlation (r = 0.61, P < 0.01) between squat 1RM and vertical jump height. Vertical jump heights for defense and forward players were significantly higher compared with midfield players. Mean results from the laboratory test were 63.7 mL¬?kg-1¬?min-1 or 188.6 mL¬?kg-0.75¬?min-1 for maximal oxygen uptake, 150 kg or 8.0 kg¬?mb-0.67 for 90¬? squats, 79.9 kg or 4.4 kg¬?mb-0.67 for bench press. Mean values of vertical jump height were 54.9 cm.
To evaluate exercise procedures to test the endurance capacity during soccer, individual results in laboratory and field tests were compared to physical Performance during the match and further to Performance during long term, intermittent exercise. Twenty professional soccer players were video-taped during competitive soccer matches, and the longest total distance (match-distance) and high intensity distance were determined. Blood lactate and maximum oxygen uptake (VÃáO2max) were measured during treadmill running. The subjects also carried out a continuous and an interval field test. Further-more, eight players performed a prolonged, soccer-specific, intermittent test to exhaustion. Muscle enzymes and morphological characteristics were determined in biopsy samples obtained from the m. gastrocnemius. The distance covered during the prolonged, intermittent test (mean: 16.3 km; r?§nge: 14.8-18.5 km) was not related to match-distance (r = 0.16), however, its correlation coefficient with high intensity distance covered during the match was 0.70. The interval field test distance was strongly correlated (r = 0.83) with the distance covered during the prolonged, intermittent test distance. VÃáO2max (r = 0.64) and blood lactate concentrations during submaximal running (r = 0.58) were related to match-distance, but not to the prolonged intermittent test distance (r = 0.18 and r = 0.27, respectively). The muscle enzyme activities and the morphological variables were not related to match activities nor to prolonged, intermittent exercise Performance. The pre-sent data suggest that the interval field test can be used to evaluate long term, intermittent exercise Performance and perhaps to test the endurance Performance of soccer players, and that for well-trained athletes muscle characteristics, VÃáO2max and blood lactate concentration during submaximal running are not sensitive measurements of endurance capacity during intermittent exercise.
Soccer entails intermittent exercise with bouts of short, intense activity punctuating longer periods of low-level, moderate-intensity exercise. High levels of blood lactate may sometimes be observed during a match but the active recovery periods at submaximal exercise levels allow for its removal on a continual basis. While anaerobic efforts are evident in activity with the ball and shadowing fast-moving opponents, the largest strain is placed on aerobic metabolism. On average, competitive soccer corresponds to an energy expenditure of about 75% maximal aerobic power. The energy expenditure varies with playing position, being highest among midfield players. Muscle glycogen levels can be reduced towards the end of a game, the level of reduction being reflected in a decrease in work rate. Blood glucose levels are generally well-maintained, although body temperature may rise by 2 C even in temperate conditions. The distance covered by players tends to under-reflect the energy expended. Unorthodox modes of motion - running backwards and sideways, accelerating, decelerating and changing direction- accentuate the metabolic loading. These are compounded by the extra requirements for energy associated with dribbling the ball and contesting possession. The overall energy expended is extreme when players are required to play extratime in tournaments. Training, nutritional and tactical strategies may be used to reduce the effects of fatigue that may occur late in the game.
The aim of this study was to assess physical fitness, match performance and development of fatigue during competitive matches at two high standards of professional soccer. Computerized time-motion analyses were performed 2-7 times during the competitive season on 18 top-class and 24 moderate professional soccer players. In addition, the players performed the Yo-Yo intermittent recovery test. The top-class players performed 28 and 58% more (P < 0.05) high-intensity running and sprinting, respectively, than the moderate players (2.43 ± 0.14 vs 1.90 ± 0.12 km and 0.65 ± 0.06 vs 0.41 ± 0.03 km, respectively). The top-class players were better (11%; P < 0.05) on the Yo-Yo intermittent recovery test than the moderate players (2.26 ± 0.08 vs 2.04 ± 0.06 km, respectively). The amount of high-intensity running, independent of competitive standard and playing position, was lower (35-45%; P < 0.05) in the last than in the first 15 min of the game. After the 5-min period during which the amount of high-intensity running peaked, performance was reduced (P < 0.05) by 12% in the following 5 min compared with the game average. Substitute players (n = 13) covered 25% more (P < 0.05) ground during the final 15 min of high-intensity running than the other players. The coefficient of variation in high-intensity running was 9.2% between successive matches, whereas it was 24.8% between different stages of the season. Total distance covered and the distance covered in high-intensity running were higher (P < 0.05) for midfield players, full-backs and attackers than for defenders. Attackers and full-backs covered a greater (P < 0.05) distance in sprinting than midfield players and defenders. The midfield players and full-backs covered a greater (P < 0.05) distance than attackers and defenders in the Yo-Yo intermittent recovery test (2.23 ± 0.10 and 2.21 ± 0.04 vs 1.99 ± 0.11 and 1.91 ± 0.12 km, respectively). The results show that: (1) top-class soccer players performed more high-intensity running during a game and were better at the Yo-Yo test than moderate professional players; (2) fatigue occurred towards the end of matches as well as temporarily during the game, independently of competitive standard and of team position; (3) defenders covered a shorter distance in high-intensity running than players in other playing positions; (4) defenders and attackers had a poorer Yo-Yo intermittent recovery test performance than midfielders and full-backs; and (5) large seasonal changes were observed in physical performance during matches.
Anterior cruciate ligament injuries are occurring at a higher rate in female athletes compared with their male counterparts. Research in the area of anterior cruciate ligament injury has increasingly focused on the role of joint proprioception and muscle activity in promoting knee joint stability. We measured knee joint laxity, joint kinesthesia, lower extremity balance, the amount of time required to generate peak torque of the knee flexor and extensor musculature, and electromyographically assessed muscle activity in 34 healthy, collegiate-level athletes (average age, 19.6 ± 1.5 years) who played soccer or basketball or both. Independent t-tests were used to determine significant sex differences. Results revealed that women inherently possess significantly greater knee joint laxity values, demonstrate a significantly longer time to detect the knee joint motion moving into extension, possess significantly superior single-legged balance ability, and produce significantly greater electromyographic peak amplitude and area of the lateral hamstring muscle subsequent to landing a jump. The excessive joint laxity of women appears to contribute to diminished joint proprioception, rendering the knee less sensitive to potentially damaging forces and possibly at risk for injury. Unable to rely on ligamentous structures, healthy female athletes appear to have adopted compensatory mechanisms of increased hamstring activity to achieve functional joint stabilization.
In this review, we attempt to integrate the main research findings concerned with talent identification and development in soccer. Research approaches in anthropometry, physiology, psychology and sociology are considered and, where possible, integrated. Although some progress has been made in identifying correlates of playing success, it appears that no unique characteristics can be isolated with confidence. Both biological and behavioural scientists have indicated a strong genetic component in performance of sports such as soccer; nevertheless, the influence of systematic training and development programmes should not be underestimated. Weconclude that the sport and exercise sciences have an important support role in the processes of identifying, monitoring and nurturing talented soccer players towards realizing their potential.
The primary purpose of this study was to evaluate whether a preseason strength-training programme for the hamstring muscle group – emphasizing eccentric overloading – could affect the occurrence and severity of hamstring injuries during the subsequent competition season in elite male soccer players. Thirty players from two of the best premier-league division teams in Sweden were divided into two groups; one group received additional specific hamstring training, whereas the other did not. The extra training was performed 1–2 times a week for 10 weeks by using a special device aiming at specific eccentric overloading of the hamstrings. Isokinetic hamstring strength and maximal running speed were measured in both groups before and after the training period and all hamstring injuries were registered during the total observational period of 10 months. The results showed that the occurrence of hamstring strain injuries was clearly lower in the training group (3/15) than in the control group (10/15). In addition, there were significant increases in strength and speed in the training group. However, there were no obvious coupling between performance parameters and injury occurrence. These results indicate that addition of specific preseason strength training for the hamstrings – including eccentric overloading – would be beneficial for elite soccer players, both from an injury prevention and from performance enhancement point of view.
This research examined the relationship between visual search strategy, selective attention, and expertise in soccer. Experienced (n = 12) and less experienced (n = 12) soccer players moved in response to filmed offensive sequences. Experiment 1 examined differences in search strategy between the two groups, using an eye movement registration system. Experienced players demonstrated superior anticipation in 3-on-3 and 1-on-1 soccer simulations. There were no differences in search strategy in 3-on-3 situations. In 1-on-1 simulations, the experienced players had a higher search rate, involving more fixations of shorter duration, and fixated for longer on the hip region, indicating that this area was important in anticipating an opponent's movements. Experiment 2 examined the relationship between visual fixation and selective attention, using a spatial occlusion approach. In 3-on-3 situations, masking information "pick up" from areas other than the ball or ball passer had a more detrimental effect on the experienced players' performances, suggesting differences in selective attention. In 1-on-1 situations, occluding an oncoming dribbler's head and shoulders, hips, or lower leg and ball region did not affect the experienced players' performances more than the less experienced group. The disparities in search strategy observed in Experiment 1 did not directly relate to differences in information extraction. Experiment 3 used concurrent verbal reports to indicate where participants extracted information from while viewing 3-on-3 sequences. Experienced players spent less time attending to the ball or ball passer and more time on other areas of the display. Findings highlight the advantages of integrating eye movements with more direct measures of selective attention.
One hundred-eighty players in a male, senior soccer division were examined for past injuries, persisting symptoms from past injuries, and muscular tightness in the lower extremities. Soccer players were in general less flexible than a group of nonplayers of the same age (n = 86). No correlation was found between past injuries and existing muscle tightness. Sprains of the lower extremity, especially of knees and ankles, predominated among the injuries. Persistent instability symptoms were common sequels to knee and ankle injuries. It is proposed that intensive care of acute injuries will improve the late results.
Soccer is the most popular sport in the world and is performed by men and women, children and adults with different levels of expertise. Soccer performance depends upon a myriad of factors such as technical/biomechanical, tactical, mental and physiological areas. One of the reasons that soccer is so popular worldwide is that players may not need to have an extraordinary capacity within any of these performance areas, but possess a reasonable level within all areas. However, there are trends towards more systematic training and selection influencing the anthropometric profiles of players who compete at the highest level. As with other activities, soccer is not a science, but science may help improve performance. Efforts to improve soccer performance often focus on technique and tactics at the expense of physical fitness.
During a 90-minute game, elite-level players run about 10km at an average intensity close to the anaerobic threshold (80–90% of maximal heart rate). Within this endurance context, numerous explosive bursts of activity are required, including jumping, kicking, tackling, turning, sprinting, changing pace, and sustaining forceful contractions to maintain balance and control of the ball against defensive pressure. The best teams continue to increase their physical capacities, whilst the less well ranked have similar values as reported 30 years ago. Whether this is a result of fewer assessments and training resources, selling the best players, and/or knowledge of how to perform effective exercise training regimens in less well ranked teams, is not known. As there do exist teams from lower divisions with as high aerobic capacity as professional teams, the latter factor probably plays an important role.
This article provides an update on the physiology of soccer players and referees, and relevant physiological tests. It also gives examples of effective strength- and endurance-training programmes to improve on-field performance. The cited literature has been accumulated by computer searching of relevant databases and a review of the authors’ extensive files. From a total of 9893 papers covering topics discussed in this article, 843 were selected for closer scrutiny, excluding studies where information was redundant, insufficient or the experimental design was inadequate. In this article, 181 were selected and discussed. The information may have important implications for the safety and success of soccer players and hopefully it should be understood and acted upon by coaches and individual soccer players.
The existence of home advantage has been established for all major professional team sports in England and North America. The advantage was found to be greatest in soccer, with the home team currently obtaining about 64% of all points gained in the English Football League. Home advantage has changed very little since the formation of the League in 1888 and there are only small variations between the four Divisions of the League. The advantage is less marked in local derbies, in the FA Cup and in nonprofessional competitions. It is greater in the European Cup and increases as the stages of the competition progress. The allocation of three points, instead of two, for a win in the Football League has not changed home advantage, but its effect has been greatly reduced in the GM Vauxhall Conference where an away win gains more points than a home win. The statistical evidence suggests that crowd support and travel fatigue contribute less to home advantage in soccer than do the less easily quantifiable benefits of familiarity with conditions when playing at home. Further possible explanations for the advantage are discussed in the light of findings in other sports.
The aim of this study was to examine the effect of intermittent high-intensity shuttle running and fluid ingestion on the performance of a soccer skill. Nine semi-professional soccer players volunteered to participate in the study. Their mean (sx) age, body mass and maximal oxygen uptake were 20.2 +/- 0.4 years, 73.2 +/- 1.8 kg and 59.1 +/- 1.3 ml.kg-1.min-1 respectively. The players were allocated to two randomly assigned trials: ingesting or abstaining from fluid intake during a 90 min intermittent exercise protocol (Loughborough Intermittent Shuttle Test:LIST).This test was designed to simulate the minimum physical demands faced by soccer players during a game. Before and immediately after performance of the test,the players completed a soccer skill test and a mental concentration test. Performance of the soccer skill test after the "no-fluid" trial deteriorated by 5% (P < 0.05),but was maintained during the fluid trial. Mean heart rate, perceived exertion, serum aldosterone, osmolality, sodium and cortisol responses during the test were higher (P < 0.05) in the "no-fluid" trial than in the fluid trial. The results of this study suggest that soccer players should consume fluid throughout a game to help prevent a deterioration in skill performance.
The purposes of the present study were: 1) to evaluate heart rate and technical-tactical differences, if any, during "6-a-side" drills, played on 2 pitch dimensions (30x40 m and 50x40 m) and duration (3 min and 8 min); 2) to assess the variability of data between repeated experimental sessions; 3) to evaluate training intensities from heart rate at lactate threshold. Methods. Laboratory measurements of maximal oxygen consumptions, maximum heart rates and lactate thresholds were performed on 9 soccer players who played at RegioSport Sciences, IUSM of Rome, Rome, ITALIE
(2) Department of Human Physiology and Sports Medicine, Vrije Universiteit Brussel (VUB), Brussels, BELGIQUE
R?©sum?© / Abstract
Aim. The purposes of the present study were: 1) to evaluate heart rate and technical-tactical differences, if any, during "6-a-side" drills, tween test and retest sessions. Statistically significant differences in frequency distributions of heart rate were found only between the 3 min and 8 min drills played on the 40x50 m pitch. Regarding exercise intensity, significant differences (P<0.01) were found for pitch dimension, with higher intensities shown during the 30?ó40 m pitch trials. When technical data were related to time units, no differences were found among experimental settings. Conclusion. These data indicate that coaches could better modulate the training intensity by varying the pitch dimension, with the smaller individual playing area (30x40 m) having a large impact on the metabolic demands of exercise.
The aim of this study was to investigate the effect of a multi-directional soccer-specific fatigue protocol on sprinting kinematics in relation to hamstring injury risk. Nine semi-professional soccer players (Mean±SD: Age: 21.3±2.9 year; Height 185.0±8.7 cm; Body Mass 81.6±6.7 kg) completed the SAFT90; a multi-directional, intermittent 90 min exercise protocol representative of soccer match-play. The 10m sprint times and three-dimensional kinematic data were recorded using a high-speed motion capture system (Qualisys Track Manager®) every 15 min during the SAFT90. A significant time dependent increase was observed in sprint time during the SAFT90 (P<0.01) with a corresponding significant decrease in stride length (P<0.01). Analysis of the kinematic sprint data revealed significantly reduced combined maximal hip flexion and knee extension angle, indicating reduced hamstring length, between pre-exercise and half-time (P<0.01) and pre-exercise and full-time (P<0.05). These findings revealed that the SAFT90 produced time dependent impairments in sprinting performance and kinematics of technique which may result from shorter hamstring muscle length. Alterations in sprinting technique may have implications for the increased predisposition to hamstring strain injury during the latter stages of soccer match-play.
The main aim of the study was to investigate the changes of hematologic status in elite soccer players throughout a competitive season. Study was conducted with 35 male professional soccer players and the measurements were collected at the start of the conditioning period, at the start of the season, in the mid-season and at the end of the season. Blood was drawn from an antecubital vein for a complete blood count, serum iron, and transferrin and ferritin levels. We found significantly higher hematocrit at preseason assessment as compared with other sampling periods (P < 0.05). No other differences were found between any of the hematologic variables during the study. The lowest hemoglobin level, mean corpuscular volume (MCV), serum iron, ferritin and transferrin encountered in the study were Hb of 11.2 g/dl, MCV of 77.9 fl, serum iron of 34 μg/dl, ferritin of 15.1 μg/l, transferrin of 224 μg/dl in a 20-year-old soccer player at the start of the season. The variability of the iron status indicators in elite soccer players seems to be stable and poorly related to training phase during sports season.
This study was performed to compare nutritional supplementation habits for Korean professional soccer players with those for the non-athletic male adults. Information about prevalence and kinds of supplements taken, information sources, nutrition knowledge were collected. Data were obtained from 53 football players working for Korean professional football clubs and 44 non-athletic males, who answered a list of questionnaires which had been prepared in advance. The prevalence of supplement use in the soccer player group (96%) was strikingly higher than in the nonathletic male group (34%). Vitamins were taken most frequently, followed by red ginseng, multivitamin, Chinese medicine and amino acids supplements in the soccer player group, with each player taking 2.96 kinds of supplements in average. Multivitamin was the most popular supplement in the non-athletic male group. The major reason for taking supplements was not to feel and recover from fatigue in both groups. It appeared that the non-athletic males started to use supplements mostly by recommendation of friends or colleagues. Meanwhile, soccer players took supplements on their needs, with half of them (50.1%) provided with nutrition information. The most important information source was coaches for soccer players group, and mass media for the non-athletic male group. The average scores of soccer players group on basic nutrition and athletic nutrition were lower than the respective values of the non-athletic males. Among the soccer players, 68% had taken more than 3 kinds of supplements during the last year; nonetheless, more than half could not perceive the effectiveness of the supplements. Our results show that supplementation practices were widespread in soccer players, and suggest that nutrition education for proper use of supplements and overall health care is needed for soccer players.
In this study, we investigated the effect of water immersion on physical test performance and perception of fatigue/recovery during a 4-day simulated soccer tournament. Twenty high-performance junior male soccer players (age 15.9 +/- 0.6 years) played four matches in 4 days and undertook either cold-water immersion (10 +/- 0.5 degrees C) or thermoneutral water immersion (34 +/- 0.5 degrees C) after each match. Physical performance tests (countermovement jump height, heart rate, and rating of perceived exertion after a standard 5-min run and 12 x 20-m repeated sprint test), intracellular proteins, and inflammatory markers were recorded approximately 90 min before each match and 22 h after the final match. Perceptual measures of recovery (physical, mental, leg soreness, and general fatigue) were recorded 22 h after each match. There were non-significant reductions in countermovement jump height (1.7-7.3%, P = 0.74, eta(2) = 0.34) and repeated sprint ability (1.0-2.1%, P = 0.41, eta(2) = 0.07) over the 4-day tournament with no differences between groups. Post-shuttle run rating of perceived exertion increased over the tournament in both groups (P < 0.001, eta(2) = 0.48), whereas the perceptions of leg soreness (P = 0.004, eta(2) = 0.30) and general fatigue (P = 0.007, eta(2) = 0.12) were lower in the cold-water immersion group than the thermoneutral immersion group over the tournament. Creatine kinase (P = 0.004, eta(2) = 0.26) and lactate dehydrogenase (P < 0.001, eta(2) = 0.40) concentrations increased in both groups but there were no changes over time for any inflammatory markers. These results suggest that immediate post-match cold-water immersion does not affect physical test performance or indices of muscle damage and inflammation but does reduce the perception of general fatigue and leg soreness between matches in tournaments.
Context: Female soccer athletes are at greater risk of anterior cruciate ligament (ACL) injury than males. Sex differences in muscle activation may contribute to the increased incidence of ACL injuries in female soccer athletes.
Objective: To examine sex differences in lower extremity muscle activation between male and female soccer athletes at the National Collegiate Athletic Association Division I level during 2 side-step cutting maneuvers.
Design: Cross-sectional with 1 between-subjects factor (sex) and 2 within-subjects factors (cutting task and phase of contact).
Setting: Sports medicine research laboratory.
Patients or Other Participants: Twenty males (age = 19.4 ± 1.4 years, height = 176.5 ± 5.5 cm, mass = 74.6 ± 6.0 kg) and 20 females (age = 19.8 ± 1.1 years, height = 165.7 ± 4.3 cm, mass = 62.2 ± 7.2 kg).
Intervention(s): In a single testing session, participants performed the running-approach side-step cut and the box-jump side-step cut tasks.
Main Outcome Measure(s): Surface electromyographic activity of the rectus femoris, vastus lateralis, medial hamstrings, lateral hamstrings, gluteus medius, and gluteus maximus was recorded for each subject. Separate mixed-model, repeated-measures analysis of variance tests were used to compare the dependent variables across sex during the preparatory and loading contact phases of each cutting task.
Results: Females displayed greater vastus lateralis activity and quadriceps to hamstrings coactivation ratios during the preparatory and loading phases, as well as greater gluteus medius activation during the preparatory phase only. No significant differences were noted between the sexes for muscle activation in the other muscles analyzed during each task.
Conclusions: The quadriceps-dominant muscle activation pattern observed in recreationally active females is also present in female soccer athletes at the Division I level when compared with similarly trained male soccer athletes. The relationship between increased quadriceps activation and greater incidence of noncontact ACL injury in female soccer athletes versus males requires further study.
This study aimed at verifying whether chronic participation in soccer training has a beneficial effect (p < 0.05) on the improvement and the maintenance of interlimb coordination performance across the lifespan and whether coordination is moderated by strength and power performances. Forty young (12 ± 1 yr), 42 adult (26 ±5 yr), and 32 older (59 ± 11 yr) male soccer players and sedentary individuals were administered in-phase (IP) and antiphase (AP) synchronized (80, 120, and 180 bpm) hand and foot flexions and extensions, handgrip and countermovement jump (CMJ) tests. Regardless of age, soccer players always showed better performances (handgrip: 383 ± 140 N; CMJ: 28.3 ± 8.7 cm; IP: 55.2 ± 12.9 s; and AP: 31.8 ± 25.0 s) than sedentary individuals (handgrip: 313 ± 124 N; CMJ: 21.0 ± 9.4 cm; IP: 46.7 ± 20.2 s, and AP: 21.1 ± 23.9 s). With respect to IP and AP performances, a hierarchical model (p < 0.0001) emerged for CMJ, explaining 30% and 26% of the variance for IP and AP, respectively. In contrast, handgrip did not provide increments in the explained variance. Results indicate that chronic soccer training is beneficial to develop strength, CMJ, and interlimb synchronization capabilities in children, to reach higher levels of proficiency in adults, and to maintain performance in older individuals. The predicted role of CMJ on interlimb coordination indicates that a fine neuromuscular activation timing is central for both jump and coordinative performances. In practice, to induce higher attentional control and executive function in open skill sport athletes and to better prepare players to cope with the demands of their match, coaches should modulate complex motor behaviors with increasing velocity of execution and are strongly recommended to make use of technical and tactical drills that focus on the player's agility under time pressure to induce higher attentional control and executive function.
The aim of this study was to investigate maximum aerobic power (VO2 max) and anaerobic threshold
(AT) as determinants of training status among professional soccer players. Twelve professional 1st team
British male soccer players (age: 26.2 ± 3.3 years, height: 1.77 ± 0.05 m, body mass: 79.3 ± 9.4 kg)
agreed to participate in the study and provided informed consent. All subjects completed a combined test
of anaerobic threshold (AT) and maximum aerobic power on two occasions: Test 1) following 5 weeks
of low level activity at the end of the off-season and Test 2) immediately following conclusion of the
competitive season. AT was assessed as both lactate threshold (LT) and ventilatory threshold (VT ). There
was no change in VO2 max between Test 1 and Test 2 (63.3 ± 5.8 ml⋅kg-1⋅min-1 vs. 62.1 ± 4.9 ml⋅kg-
1‚ãÖmin-1 respectively), however, the duration of exercise tolerance (ET) at VO2 max was significantly
extended from Test 1 to Test 2 (204 ± 54 vs. 228 ± 68 s respectively) (P<0.01). LT oxygen consumption
was significantly improved in Test 2 versus Test 1 (P<0.01) VT was also improved (P<0.05). There was
no significant difference in VO2 (ml‚ãÖkg-1‚ãÖmin-1) corresponding to LT and VT . The results of this study
show that VO2 max is a less sensitive indicator to changes in training status in professional soccer players
than either LT or VT
The aim of this study was to investigate the changes in anaerobic endurance of elite soccer players after traditional soccer conditioning and after the intervention in training program. Eighteen elite male soccer players volunteered to participate in the study. The study was conducted over the period of two seasons, during the pre-competitive period. The first season the players underwent the traditional soccer preparation training, whilst during the second season the intervention was made. The anaerobic training intervention consisted of interval training, 4x4min running at an intensity of 90-95% percent of HRmax, separated by periods of 3 min technical drills at 55-65% HRmax. The interval training was administrated as an extension of the regular training, three times a week over an 8-wk period. The anaerobic endurance was tested by 300-yard shuttle run test. The traditional conditioning program conducted during the first year of the study did not elicit the improvement of the anaerobic endurance as recorded on 300y shuttle run test. In the following season and after the intervention program, the repeated measurements revealed the impact of the redesigned program on parameters representing anaerobic endurance. The overall test running time improved significantly (55.74± ; ; 1.63 s vs 56.99± ; ; 1.64 s ; p<0.05) which was not observed in the season before. Also, the maximal lactate production was significantly higher (15.4± ; ; 1.23 mmol/L vs. 13.5± ; ; 1.12 mmol/L ; p<0.01) so in a better overall time the players performed better and were able to sustain higher blood lactate concentrations.
Abstract To determine the effects of simultaneous explosive strength and soccer training in young men, 8 experimental (S) and 11 control (C) players, aged 17.2 (0.6) years, were tested before and after an 11-week training period with respect to the load-vertical jumping curve [loads of 0–70 kg (counter-movement jump CMJ0–70)], 5- and 15-m sprint performances, submaximal running endurance and basal serum concentrations of testosterone, free testosterone and cortisol. In the S group, the 11-week training resulted in significant increases in the low-force portion of the load-vertical jumping curve (5–14% in CMJ0–30, P<0.01) and in resting serum total testosterone concentrations (7.5%, P<0.05), whereas no changes were observed in sprint running performance, blood lactate during submaximal running, resting serum cortisol and resting serum free testosterone concentrations. In the C group, no changes were observed during the experimental period. In the S group, the changes in CMJ0 correlated (P<0.05–0.01) with the changes in the 5-m (r=0.86) and 15-m (r=0.92) sprints, whereas the changes in CMJ40 correlated negatively with the changes in the testosterone:cortisol ratio (r=–0.84, –0.92, respectively, P<0.05). These data indicate that young trained soccer players with low initial strength levels can increase explosive strength by adding low-frequency, low-intensity explosive-type strength training. The inverse correlations observed between changes in CMJ40 and changes in the testosterone:cortisol ratio suggest that a transient drop in this ratio below 45% cannot always be interpreted as a sign of overstrain or neuroendocrine dysfunction.
The purpose of this study was to examine and compare the cardiorespiratory performance and isokinetic muscle strength between Greek soccer and basketball players of different divisions before starting the training season. Study participants included 100 soccer players and 61 basketball players, who were assigned according to the kind of sport and division. All participants underwent anthropometric measurements and performed an exercise test on a treadmill to determine maximal oxygen uptake (VÃáo2max). Peak torque for quadriceps and hamstring muscles was measured on isokinetic dynamometer at angular velocity of 60 degrees/s-1, 180 degrees/s-1, and 300 degrees/s-1. The statistical p value was set at p < 0.05.
In soccer players VÃáo2max in absolute and relative values was significantly lower in division IV compared to the other 3 divisions (3,413.4 ¬± 351.0 vs. 3,932.7 ¬± 551.2, 4,172.7 ¬± 371.8, 4,223.0 ¬± 323.8 ml¬?min-1, respectively; p < 0.001 and 46.93 ¬± 4.20 vs. 52.47 ¬± 3.66, 54.86 ¬± 3.80, 55.32 ¬± 3.33 ml¬?kg¬?min-1, respectively; p < 0.001). Basketball players presented significantly higher VÃáo2max, in absolute values, compared to soccer players for divisions II (4,586.3 ¬± 586.3 vs. 4,172.7 ¬± 371.8 ml¬?min-1; p < 0.05), III (4,319.6 ¬± 418.6 vs. 3,932.7 ¬± 551.2 ml¬?min-1; p < 0.01), and IV (4,624.0 ¬± 627.6 vs. 3,413.4 ¬± 351.0 ml¬?min-1; p < 0.001), respectively. Regarding peak torque, only basketball players showed significantly higher values at 60 degrees/sec-1 in hamstrings for III (p < 0.05) and IV division (p < 0.05).
Conclusively, the higher VÃáo2max reached by professional soccer and basketball players compared to semiprofessional and amateur ones and between the soccer and basketball players of the same division can be attributed to the different duration of the maintenance period and to the effect of the training session on each sport, respectively. Finally, a higher level of muscle strength would be preferable in soccer and basketball and would reduce the risk for injuries in the maintenance and rebuilding training periods.
Olympic-style lifts (OSL) and plyometric exercises (PE) are frequently combined with traditional resistance training (TRT) to improve athletic performance. The goal of this study was to directly compare the performance effect of TRT (30 minutes) combined with either OSL or nondepth-jump PE (15 minutes) on entry level competitive collegiate athletes. Ten female and 5 male competitive soccer players, divided into 2 groups, completed 12 weeks of triweekly training during their off-season. Countermovement vertical jump, 4 repetition maximum squat, 25-m sprint, and figure-8 drill on a 5-dot mat were conducted pre-, mid-, and postintervention. Significant improvements were made by both groups in each performance parameter over the 12-week period (p < 0.05), with no significant differences found between the training groups. Although these training modalities may achieve their results through slightly different mechanisms, the performance-related improvements may not be significantly different for entry-level collegiate athletes with little resistance training experience.
Recent research demonstrates that stretching prior to physical activity decreases performance. However, these stretching bouts are not representative of athletes during warm up procedures, as they are usually time consuming. The aim of the present study was to examine whether the duration of acute static stretching is responsible for losses in isokinetic peak torque production.
Fourteen young, male, talented, semiprofessional soccer players, from different Greek first national division teams, with an average age of 18.5±0.6 years, height of 177.6±4.3cm, body mass of 70.8±3.5kg and 8.4±0.5 years of training, were randomly selected to take part in the study. All participants performed three static stretching protocols, in nonconsecutive training session. The first stretching protocol was performed once for 30s (volume 30), the second 10 times for 30s (volume 300) and the third 16 times for 30s (volume 480).
Range of motion (ROM) was determined during knee flexion, using a goniometer. The peak torque of the dominant leg extensors was measured on a Cybex NORM dynamometer at angular velocities of 60, 90, 150, 210 and 270¬?¬?s‚àí1. The results of the statistical analysis indicated that peak torque remained unchanged following the static stretching for 30s in all angular velocities, while it decreased (P<0.01 to P<0.001) following the static stretching for 5 or 8min in all angular velocities. The findings suggest that a single stretch (training volume 30s) does not produce decreases in peak torque compared to multiple stretches (training volume 480s).
The purpose of this study was to evaluate changes in anaerobic endurance in elite First-league soccer players throughout 2 consecutive seasons, in 2 phases, with and without high-intensity situational drills. Eighteen soccer players were tested before and after the 8-week summer conditioning and again in the next season. The measured variables included 300-yard shuttle run test, maximal heart rate, and maximal blood lactate at the end of the test. During the first phase of the study, the traditional sprint training was performed only 2 ?ó weeks and consisted of 15 bouts of straight-line sprinting. In the second year the 4 ?ó 4 min drills at an intensity of 90-95% of HRmax, separated by periods of 3-minute technical drills at 55-65% of HRmax were introduced. Statistical significance was set at P ‚⧠0.05. The traditional conditioning program conducted during the first year of the study did not elicit an improvement in anaerobic endurance as recorded in the 300-yard shuttle run test. After the intervention, the overall test running time improved significantly (55.74 ¬± 1.63 s vs. 56.99 ¬± 1.64 s; P < 0.05) with the maximal blood lactate at the end of the test significantly greater (15.4 ¬± 1.23 mmol¬?L-1 vs. 13.5 ¬± 1.12 mmol¬?L-1. P < 0.01). As a result, this study showed some indication that situational high-intensity task training was more efficient than straight-line sprinting in improving anaerobic endurance measured by the 300-yard shuttle run test.
Studies comparing warm-up procedures involving controlled dynamic movements (i.e., dynamic warm-up) with the traditional warm-up practice of performing a brief bout of light aerobic activity followed by static stretching exercises (i.e., static warm-up) show that the content of a particular warm-up protocol can impact subsequent exercise performance. However, little is known to date about the time window that exists after the completion of a standard warm-up for these performance differences to remain visible. Moreover, the need for sport-specific studies on what may constitute a preferred warm-up approach is now widely recognized.
Purpose The purpose of this study was (a) to compare the effects of a standardized static and dynamic warm-up protocol on selected performance measures, and (b) to examine the effects of three predetermined time intervals following the completion of the dynamic warm-up protocol on the same physical performance outcomes.
Methods Twenty female high school varsity soccer players (age: 16.05±0.83 yrs) participated in an initial protocol familiarization session and four randomly assigned experimental test sessions consisting of a 10-min static warm-up with a ≤ 2-min time window until performance testing (S2), and a 10-min dynamic warm-up with three different rest intervals (≤ 2-min [D2]; 5-min [D5]; 15-min [D15]) prior to testing. Both the static and dynamic warm-up protocols were adopted from Faigenbaum et al. (2005) and consisted of either 5 min of light jogging followed by 5 min of prescribed static stretching exercises, or 10 min of prescribed dynamic warm-up exercises that progressed from moderate to high intensity. The physical performance test battery included a standing long jump, a short distance (9.14-meters) sprint, and a sit-and-reach flexibility test. The order of the four different warm-up procedures was randomly assigned with individual test sessions separated by at least 48 hours.
Analysis/Results Data was analyzed using repeated measures ANOVA including Duncan's new multiple range test for post hoc comparisons. Results indicate that D2 (1.97+0.07 sec) and D5 (1.97+0.08 sec) sprint times were faster compared to S2 (2.03+0.09 sec) and D15 (2.01+0.09 sec) (p<0.05). Standing long jump performance was better in D5 (180.85+17.67 cm) compared to D15 (176.28+19.56 cm) (p<0.05). There was no significant difference among the warm-up procedures for sit-and-reach flexibility scores (p>0.05).
Conclusions The present findings extend the empirical knowledge base about the performance modulating potential of static and dynamic warm-up protocols. Moreover, they offer valuable directions for improving the design and timing of warm-up procedures in modern soccer.
Background. There have been many studies on soccer, but few evaluations of the physiological function of professional soccer players. The aim of this work was to evaluate seasonal variation - from September to February - in anthropometric and physiological variables in a Spanish professional soccer team (n=15). Methods. Anthropometric measurements were obtained following the standardised techniques adopted by the International Society for the Advancement of Kinanthropometry (ISAK). A maximal treadmill test with breath-by-breath gas analysis was carried out to evaluate the aerobic condition and a Jump test was used to measure muscle performance and strength in the lower limbs. Results. There were no significant variations in body mass, although a statistically significant decrease (p<0.05) in fat percentage and sum of six skinfolds was observed. The somato-type (Heath-Carter) was mesomorphic without any change observed throughout the season. The mean VO2max in the first test (65.5 ml.kg-1.min-1) had not changed by the second one (66.4 ml.kg-1.min-1). There were no significant differences in maximal heart rate (185 vs 185 beats.min-1) and treadmill speed at VO2max (16.1 vs 15.8 km.h-1). At the anaerobic threshold, there were significant differences (p<0.05) in speed (12.4 vs 13.1 km.h-1) and heart rate (164 vs 168 beats.min-1) as the season progressed. When the data were expressed as a percentage of maximal values obtained, we observed that the speed in the first test was 77 and 83% in the second test. For heart rate, values were 89 and 91%, and for oxygen uptake 77 and 79%. The Jump test did not show any significant change during the season. Conclusions. We can conclude from these results that professional soccer players have good fitness from the beginning of the Spanish League - with a high V.O2max - and the changes observed depend on the initial values.
Background: A high level of strength is inherent in elite soccer play, but the relation between maximal strength and sprint and jumping performance has not been studied thoroughly.
Objective: To determine whether maximal strength correlates with sprint and vertical jump height in elite male soccer players.
Methods: Seventeen international male soccer players (mean (SD) age 25.8 (2.9) years, height 177.3 (4.1) cm, weight 76.5 (7.6) kg, and maximal oxygen uptake 65.7 (4.3) ml/kg/min) were tested for maximal strength in half squats and sprinting ability (0–30 m and 10 m shuttle run sprint) and vertical jumping height.
Result: There was a strong correlation between maximal strength in half squats and sprint performance and jumping height.
Conclusions: Maximal strength in half squats determines sprint performance and jumping height in high level soccer players. High squat strength did not imply reduced maximal oxygen consumption. Elite soccer players should focus on maximal strength training, with emphasis on maximal mobilisation of concentric movements, which may improve their sprinting and jumping performance.
Information about the influence of different practice levels on physical characteristics of a large number of soccer players is lacking. Therefore we assessed muscular strength and anaerobic power of elite, subelite and amateur soccer players to clarify what parameters distinguish the top players from the less successful. We tested 95 soccer players from the French first division (elite), second division (subelite), and amateurs and determined the isokinetic strength of the knee extensor and flexor muscles at angular velocities from - 120 ¬? ¬? s-1 to 300 ¬? ¬? s-1. Vertical jump, 10 m sprint, 30 m sprint and maximum ball speed during shooting were also measured. The elite players had higher knee flexor torque than the amateurs at all angular velocities (p < 0.05), except at 300 ¬? ¬? s-1. The hamstring/quadriceps ratios proposed with two different methods were significantly lower in the amateur group than in the elite group (p < 0.05), except at 300 ¬? ¬? s-1. Maximum ball speed during shooting and speed over 30 m sprint were not different between elite, subelite, and amateur players while speed over a 10 m sprint was significantly slower in amateur players and faster in the elite group (p < 0.05). Although performance in soccer is not determined only by measurable variables, professional players differ from amateurs in terms of knee flexor muscle strength and short-distance sprinting speed. Based on these findings we conclude that hamstring strength is extremely important in soccer players for joint stabilization during various tasks, notably in eccentric action. Further, short-sprinting performance may mirror actual game situations at high level and could be an important determinant of match-winning actions.
Soccer is one of the most popular sports in the world. There is still much uncertainty and debate surrounding its physiological requirements because emphasis is on skills to the neglect of fitness, conservative training methods and the difficulty of studying the sport scientifically. The frequently found values for total distance covered in a game of about 10 km and an above-average, though not outstanding, maximum oxygen uptake of 60 ml/kg/min suggest a moderate overall aerobic demand. A comparison of top teams and players with less able participants indicates that the components of anaerobic fitness-speed, power, strength and the capacity of the lactic acid system may differentiate better between the 2 groups. Generally, there is a reduction in the level of activity in the second half of games compared with the first. There is some evidence that increased aerobic fitness may help counteract this. Progressively lower muscle glycogen stores are one likely cause of reduction in activity, and nutrition also appears to be a key factor in minimising performance deterioration, both in terms of overall diet and, more particularly, the ingestion of carbohydrates immediately before, during and after a game. There are evolutionary trends in the sport such as greater frequency of games, changes in the roles of players, and new strategies and tactics which are placing increasing demands on the all-round fitness of players. Many studies indicate scope for improvement in player fitness. The challenge for coaches and players is to meet these fitness requirements without sacrificing the skill work which makes the sport unique.
Background: Muscular tightness is frequently postulated as an intrinsic risk factor for the development of a muscle injury. However, very little prospective data exist to prove this.
Hypothesis: Increased muscle tightness identifies a soccer player at risk for a subsequent musculoskeletal lesion.
Study Design: Prospective cohort study.
Methods: We examined 146 male professional soccer players before the 1999–2000 Belgian soccer competition. None of the players had a history of muscle injury in the lower extremities in the previous 2 years. The flexibility of the hamstring, quadriceps, adductor, and calf muscles of these players was measured goniometrically before the start of the season. All of the examined players were monitored throughout the season to register subsequent injuries.
Results: Players with a hamstring (N = 31) or quadriceps (N = 13) muscle injury were found to have significantly lower flexibility in these muscles before their injury compared with the uninjured group. No significant differences in muscle flexibility were found between players who sustained an adductor muscle injury (N = 13) or a calf muscle injury (N = 10) and the uninjured group.
Conclusions: These results indicate that soccer players with an increased tightness of the hamstring or quadriceps muscles have a statistically higher risk for a subsequent musculoskeletal lesion.
Clinical Significance: Preseason hamstring and quadriceps muscle flexibility testing can identify male soccer players at risk of developing hamstring and quadriceps muscle injuries.
Background: In professional soccer, a significant amount of training time is used to improve players' aerobic capacity. However, it is not known whether soccer specific training fulfils the criterion of effective endurance training to improve maximal oxygen uptake, namely an exercise intensity of 90–95% of maximal heart rate in periods of three to eight minutes.
Objective: To determine whether ball dribbling and small group play are appropriate activities for interval training, and whether heart rate in soccer specific training is a valid measure of actual work intensity.
Methods: Six well trained first division soccer players took part in the study. To test whether soccer specific training was effective interval training, players ran in a specially designed dribbling track, as well as participating in small group play (five a side). Laboratory tests were carried out to establish the relation between heart rate and oxygen uptake while running on a treadmill. Corresponding measurements were made on the soccer field using a portable system for measuring oxygen uptake.
Results: Exercise intensity during small group play was 91.3% of maximal heart rate or 84.5% of maximal oxygen uptake. Corresponding values using a dribbling track were 93.5% and 91.7%. No higher heart rate was observed during soccer training.
Conclusions: Soccer specific exercise using ball dribbling or small group play may be performed as aerobic interval training. Heart rate monitoring during soccer specific exercise is a valid indicator of actual exercise intensity.
Injuries occurring in three Swedish elite soccer teams were analyzed during 1 year. A total of 49 of 64 players (75%) sustained 85 injuries. The incidence of injury during games was 13 injuries per 1000 hours, while the incidence during training was 3 injuries per 1000 hours. Twenty percent of the injuries required hospital facili ties. The majority of the traumatic injuries (93%) were to the lower extremities, with one third of the total injuries occurring in the knee. Overuse injuries ac counted for 35% of all injuries and occurred mainly during preseason training and at the end of each sea son. Conversely, the majority of traumatic injuries oc curred during games, equally distributed between the first and second halves with a predominance toward the end of each half. The position of the player within the team did not influence injury rate. The referee considered 28% of the traumatic injuries to be caused by violation of existing rules. Thirty-four percent of the injuries were major, causing more than 1 month of absence from training and/or games. Eleven knee in juries required surgical intervention revealing seven rup tured ACLs, of which three were chronic. At followup, 9 to 18.5 months after injury, 4 of 12 players with major knee injuries had returned to play at the elite level. The others had either been transferred to lower divisions or were still in rehabilitation.
BACKGROUND: The aim of the current investigation was to determine the movement profiles of elite South American soccer players during international competition and examine the relationship between anthropometric profile and work-rate variables. METHODS: Seventeen full-time professional soccer players were filmed while competing for their countries. Anthropometric profiles were obtained for eleven of these players. Six full-time professional players from the English Premier League were also filmed for comparative purposes. RESULTS: The South American international players covered significantly less (p<0.05) total distance during match-play than English Premier League players (International, 8638+/-1158 m; English Premier League, 10104+/-703 m). The total distance covered during the second half of the game was significantly reduced (p<0.05) compared to the first half distance for both groups of players (mean+/-SD first half 4605+/-625 m; mean+/-SD second half 4415+/-634 m). The data for both groups of players were combined to evaluate positional differences in the workrate profile. Midfield players covered a significantly greater (p<0.05) distance than forward players (midfield, 9826+/-1031 m; forwards, 7736+/-929 m) and defenders covered a greater (p<0.05) distance jogging backwards than forward players (defenders, 276+/-155 m; forwards, 68+/-25 m). Forwards sprinted a greater distance (p<0.05) than defensive players (defenders, 231+/-142 m; forwards, 557+/-142 m). Mean somatotype was a balanced mesomorph (2-5 1/2-2). Body mass and muscle mass was related to the total distance covered (r=0.43, r=0.53, p<0.05). CONCLUSIONS: Based on these data, it seems that an individual's work-rate profile is dependent upon the type of competition and the playing position. Relationships between anthropometric profile and work-rate are complex due to the interaction between the variables that determine work-rate.
Summary The top players in an elite soccer team volunteered as subjects in a study to determine intramuscular glycogen concentrations after a regular season match, and whether optimal glycogen levels could be re-attained prior to the team's next match. Fifteen players were biopsied in the M. vastus lateralis following a regular season game (Day I). Of these, eight were biopsied 24 h later in the evening of a free day during which no training session was held (Day II), and again 24 h later after a very light training session (Day III). Muscle glycogen concentrations for the eight players averaged (¬± SD) 45.9¬±7.9, 68.9¬±2.7, and 72.8¬±8.3 mmol glucose units ?ókg‚Äì1 wet muscle weight on Day I, Day II, and Day III respectively. Dietary records were analysed during a week of peak season competition and training. The average daily total energy consumption and total quantity of carbohydrates consumed were less than what is normally consumed by athletes in similar sports. The inability of the players to maintain even normal, resting levels of muscle glycogen is probably related to their dietary practices.
Women's soccer injuries in relation to the menstrual cycle and oral contraceptive use. Med. Sci. Sports Exerc, Vol. 21, No. 2, pp. 126-129, 1989. During 1984, 86 women soccer players answered detailed questionnaires concerning contraceptive use, menstruation data, premenstrual and menstrual symptoms, and data concerning soccer activities including injuries. This prospective study showed that women soccer players were more susceptible to traumatic injuries during the premenstrual and menstrual period compared to the rest of the menstrual cycle (P < 0.05), especially among players with premenstrual symptoms such as irritability/irascibility, swelling/discomfort in the breasts, and swelling/congestion in the abdomen. It was also found that women using contraceptive pills had a lower rate of traumatic injuries (P < 0.05) compared to women who were not on the Pill. The results can be explained by the fact that oral contraceptives ameliorate some symptoms of the premenstrual and menstrual period which might also affect coordination and hence the risk of injury.
The aim of this study was to compare the effects of specific (small-sided games) vs. generic (running) aerobic interval training on physical fitness and objective measures of match performance in soccer. Forty junior players were randomly assigned to either generic (n=20) or specific (n=20) interval training consisting of 4 bouts of 4 min at 90-95 % of maximum heart rate with 3 min active rest periods, completed twice a week. The following outcomes were measured at baseline (Pre), after 4 weeks of pre-season training (Mid), and after a further 8 weeks of training during the regular season (Post): maximum oxygen uptake, lactate threshold (Tlac), running economy at Tlac, a soccer-specific endurance test (Ekblom's circuit), and indices of physical performance during soccer matches (total distance and time spent standing, walking, and at low- and high-intensity running speed). Training load, as quantified by heart rate and rating of perceived exertion, was recorded during all training sessions and was similar between groups. There were significant improvements in aerobic fitness and match performance in both groups of soccer players, especially in response to the first 4 weeks of pre-season training. However, no significant differences between specific and generic aerobic interval training were found in any of the measured variables including soccer specific tests. The results of this study showed that both small-sided games and running are equally effective modes of aerobic interval training in junior soccer players.
The review of the effects of artificial turf and natural grass on surface-related traumatic injuries in soccer suggests that surfaces with artificial turf produce more abrasion injuries than surfaces with natural grass. Most authors report no significant difference in injury frequencies for the number of traumatic injuries. However, some authors report fewer traumatic injuries on artificial turf, especially after a period of adaptation on the artificial turf. A difference in injury pattern and injury mechanism when playing on different types of surfaces has been suggested, as well as an increased injury risk for frequent alternating between different playing surfaces. The relationship between knee and ankle injuries and the fixation of the foot to the ground is not yet evaluated in soccer. In American football, the severity and incidence of knee and ankle injuries were reported to be significantly lower when using shoes with lower friction properties. However, in American football severe injuries typically occur in collision situations often independent of the surface. Soccer is characterised by sprinting, stopping, cutting and pivoting situations, where shoe-surface relations are essential and frictional resistance must be within an optimal range. Future research should address this compromise between performance and protection.
The purpose of this study was to evaluate the physiological functions of a professional soccer team in the North American Soccer League (NASL). Eighteen players were evaluated on cardiorespiratory function, endurance performance, body composition, blood chemistry, and motor fitness measures near the end of their competitive season. The following means were observed: age, 26 yrs; height, 176 cm; weight 75.5 kg; resting heart rate, 50 beats/min; maximum heart rate (MHR), 188 beats/min; maximum oxygen intake (VO2 max), 58.4 ml/kg-min-1; maximum ventilation (VEmax BTPS), 154 L/min; body fat, 9.59%; 12-min run, 1.86 miles; and Illinois agility run, 15.6 secs. Results on resting blood pressure, serum lipids, vital capacity, flexibility, upper body strength, and vertical jump tests were comparable to values found for the sedentary population. Comparing the results with previously collected data on professional American Football backs indicated that the soccer players were shorter; lighter in body weight; higher in VO2 max (4 ml/kg-min-1) and body fat (1.8%); and similar in MHR, VE max, and VC. The 12-min run scores were similar to the initial values observed for the 1970 Brazilian World Cup Team. The agility run results were superior to data collected from other groups. Their endurance capabilities, agility, and low percent of body fat clearly differentiate them from the sedentary population and show them to be similar to that of professional American football backs.
Physical activity is known to induce oxidative stress in individuals subjected to intense exercise. In this study, we investigated the lipoprotein profile and the plasma antioxidant status in a group of soccer players engaged in a regular training programme. As was expected for aerobic exercise, high-density lipoprotein-cholesterol (HDL-C) and HDL3-C levels were significantly increased in the sportsmen (P < 0.05). Total plasma antioxidant capacity was 25% higher in sportsmen than in controls (P < 0.005). Accordingly, plasma hydrosoluble antioxidant levels (ascorbic acid and uric acid) were found to be significantly elevated in the soccer players (P < 0.005). In addition, these subjects showed high concentrations of a-tocopherol in plasma compared with controls (P < 0.005). Furthermore, an increase in plasma superoxide dismutase activity was also observed in relation to exercise (P < 0.01). The elevation in plasma activities of antioxidant enzymes and the higher levels of free radical scavengers of low molecular mass may compensate the oxidative stress caused by physical activity. High levels of high-density lipoprotein in plasma may offer additional protection by inhibiting low-density lipoprotein oxidation and thus liposoluble antioxidant consumption. Therefore, soccer players under regular training show an improved plasma antioxidant status in comparison to sedentary controls.
This review describes when fatigue may develop during soccer games and the potential physiological mechanisms that cause fatigue in soccer. According to time?–?motion analyses and performance measures during match-play, fatigue or reduced performance seems to occur at three different stages in the game: (1) after short-term intense periods in both halves; (2) in the initial phase of the second half; and (3) towards the end of the game. Temporary fatigue after periods of intense exercise in the game does not appear to be linked directly to muscle glycogen concentration, lactate accumulation, acidity or the breakdown of creatine phosphate. Instead, it may be related to disturbances in muscle ion homeostasis and an impaired excitation of the sarcolemma. Soccer players' ability to perform maximally is inhibited in the initial phase of the second half, which may be due to lower muscle temperatures compared with the end of the first half. Thus, when players perform low-intensity activities in the interval between the two halves, both muscle temperature and performance are preserved. Several studies have shown that fatigue sets in towards the end of a game, which may be caused by low glycogen concentrations in a considerable number of individual muscle fibres. In a hot and humid environment, dehydration and a reduced cerebral function may also contribute to the deterioration in performance. In conclusion, fatigue or impaired performance in soccer occurs during various phases in a game, and different physiological mechanisms appear to operate in different periods of a game.
The aims of this study were to describe and determine the test-retest reliability of an exercise protocol, the Loughborough Intermittent Shuttle Test (the LIST), which was designed to simulate the activity pattern characteristic of the game of soccer. The protocol consisted of two parts: Part A comprised a fixed period of variable-intensity shuttle running over 20 m; Part B consisted of continuous running, alternating every 20 m between 55% and 95% VO2max, until volitional fatigue. Seven trained games players (age 21.5 +/- 0.9 years, height 182 +/- 2 cm, body mass 80.1 +/- 3.6 kg, VO2max 59.0 +/- 1.9 ml kg-1 min-1; mean sx ) performed the test on two occasions (Trial 1 and Trial 2), at least7 days apart, to determine the test-retest reliability of the sprint times and running capacity. The physiological and metabolic responses on both occasions were also monitored. The participants ingested water ad libitum during the first trial, and were then prescribed the same amount of water during the second trial. The 15 m sprint times during Trials 1 and 2 averaged 2.42 +/- 0.04 s and 2.43 +/- 0.04 s, respectively. Run time during Part B was 6.3 +/- 2.0 min for Trial 1 and 6.1 +/- 1.3 min for Trial 2. The 95% limits of agreement for sprint times and run times during Part B were -0.14 to 0.12 s and -3.19 to 2.16 min respectively. There were no differences between trials for heart rate, rating of perceived exertion, body mass change during exercise, or blood lactate and glucose concentrations during the test. Thus, we conclude that the sprint times and the Part B run times were reproducible within the limits previously stated. In addition, the activity pattern and the physiological and metabolic responses closely simulated the match demands of soccer.
The knee extensor and knee flexor strengths were measured isokinetically (30¬?, 180¬?/s) and isometrically with a Cybex II device in three groups of male soccer players (national team players, n = 13; division I, n = 15; division IV, n = 180) and a group of nonsoccer players (n = 32). There were difference in strength between soccer players and nonsoccer players and between players from different divisions. Correction for body surface area did not affect the results. The knee flexor/knee extensor ratio (H/Q ratio) was significantly higher for soccer players than for nonsoccer players. The fast-speed/slow-speed ratio for knee extensors was higher for nonsoccer players and for national team players than for players from divisions I and IV.
Purpose: This investigation examined the effects of creatine (Cr) supplementation on intermittent high-intensity exercise activities specific to competitive soccer.
Methods: On two occasions 7 d apart, 17 highly trained male soccer players performed a counter-movement jump test (CMJT), a repeated sprint test (RST) consisting of six maximal 15-m runs with a 30-s recovery, an intermittent endurance test (IET) consisting of forty 15-s bouts of high-intensity running interspersed by 10-s bouts of low-intensity running, and a recovery CMJT consisting of three jumps. After the initial testing session, players were evenly and randomly included in a CREATINE (5 g of Cr, four times per day for 6 d) or a PLACEBO group (same dosage of maltodextrins) using a double-blind research design.
Results: The CREATINE group's average 5-m and 15-m times during the RST were consistently faster after the intervention (0.95 ± 0.03 vs 0.97 ± 0.02 s, P < 0.05 and 2.29 ± 0.08 vs 2.32 ± 0.07 s, P = 0.07, respectively). Neither group showed significant changes in the CMJT or the IET. The CREATINE group's recovery CMJT performance relative to the resting CMJT remained unchanged postsupplementation, whereas it tended to decrease in the PLACEBO group.
Conclusion: In conclusion, acute Cr supplementation favorably affected repeated sprint performance and limited the decay in jumping ability after the IET in highly trained soccer players. Intermittent endurance performance was not affected by Cr.
Recent investigations have focused on the possible ergogenic value of supplementing the athletes' diet with approximately 20 g¬?d-1 of creatine (Cr) monohydrate for 5 to 7 d. It has often been shown that this type of acute Cr supplementation can result in increased total muscle Cr (5,15,21,24,25,27,29,30,39,49) and phosphocreatine (PCr) (15,21,29,30,52) concentrations. Studies have also shown that this elevated intramuscular PCr can enhance the rate of ATP and PCr resynthesis after high-intensity efforts, causing a delayed onset of muscular fatigue and an increased performance during repeated bouts of high-intensity exercise (1,5,15,18,26,27,35).
In a recent review of the literature, it was suggested that highly trained athletes who participate in sports in which performance relies on repeated efforts could benefit from Cr ingestion by means of an increased ability to perform intermittent high-intensity exercise bouts either during training or competition (38). This would be the case in competitive soccer. Indeed, it has been reported that, among professional players, high-intensity running accounts for about 8-18% of the total playing time during a soccer match, whereas 70-80% of the playing time is spent walking or running at a low intensity (8,45,53,54). In addition to the intermittent high-intensity running pattern, players also perform 10-19 tackles and 9-13 headings, most of which involve jumping for aerial possession of the ball (8,19,54). Moreover, a relationship has been reported between the quality of the soccer play and the amount of high-intensity exercise performed during a match (19).
This investigation was thus designed to determine whether acute oral Cr supplementation could enhance performance and recovery in highly trained soccer players performing sport-specific exercise tasks, and to analyze the influence of this intervention on the main metabolic pathways supplying the necessary energy for the completion of those tasks.
Fatigue represents a reduction in the capability of muscle to generate force. The aim of the present study was to establish the effects of exercise that simulates the work rate of competitive soccer players on the strength of the knee extensors and knee flexors. Thirteen amateur soccer players (age 23.3¬±3.9 years, height 1.78¬±0.05 m, body mass 74.8¬±3.6 kg; mean¬±s) were tested during the 2000-2001 soccer season. Muscle strength of the quadriceps and hamstrings was measured on an isokinetic dynamometer. A 90 min soccer-specific intermittent exercise protocol, incorporating a 15 min half-time intermission, was developed to provide fatiguing exercise corresponding in work rate to a game of soccer. The exercise protocol, performed on a programmable motorized treadmill, consisted of the different intensities observed during soccer match-play (e.g. walking, jogging, running, sprinting). Muscle strength was assessed before exercise, at half-time and immediately after exercise. A repeated-measures analysis of variance showed significant reductions (P <0.001) in peak torque for both the quadriceps and hamstrings at all angular velocities (concentric: 1.05, 2.09, 5.23 rad ¬? s-1; eccentric: 2.09 rad ¬? s-1). The peak torque of the knee extensors (KE) and knee flexors (KF) was greater before exercise [KE: 232¬±37, 182¬±34, 129¬±27, 219¬±41 N ¬? m at 1.05, 2.09 and 5.23 rad ¬? s-1 (concentric) and 2.09 rad ¬? s-1 (eccentric), respectively; KF: 126¬±20, 112¬±19, 101¬±16, 137¬±23 N ¬? m] than at half-time (KE: 209¬±45, 177¬±35, 125¬±36, 214¬±43 N ¬? m; KF: 114¬±31, 102¬±20, 92¬±15, 125¬±25 N ¬? m) and greater at half-time than after exercise (KE: 196¬±43, 167¬±35, 118¬±24, 204¬±43 N ¬? m; KF: 104¬±25, 95¬±21, 87¬±13, 114¬±27 N ¬? m). For the hamstrings : quadriceps ratio, significant changes were found (P <0.05) for both legs, the ratio being greater before than after exercise. For fast : slow speed and left : right ratios, no significant changes were found. We conclude that there is a progressive reduction in muscle strength that applies across a range of functional characteristics during exercise that mimics the work rate in soccer.
Basketball and soccer are two games with different training and playing procedures. The purpose of this study was to examine the maximal voluntary peak torques of the quadriceps and hamstring muscles, and the torque ratio between these muscle groups in basketball players (n = 61) and soccer players (n = 51) participating in teams of different divisions. Isokinetic peak torques were measured using the Cybex II isokinetic dynamometer at 60 and 180 degrees.s-1. Basketball players of the national team produced higher peak torque values of quadriceps muscles than the other basketball players of different divisions (p < 0.05 to p < 0.001). Hamstring peak torques of the national basketball team were significantly higher the only velocities measured compared with the players from division II and IV (p < 0.05). Peak torque values of quadriceps muscles relative to body weight were significantly higher in the national basketball team compared with basketball players from division I. No significant differences were found in peak torque values of quadriceps and hamstring muscles within the different basketball and soccer divisions. Peak torque expressed in absolute terms was significantly higher in basketball players than in soccer players (p < 0.05 to p < 0.001). However, these differences were not significant when the strength of quadriceps and hamstring muscles was expressed relative to body weight. The H/Q ratio did not differ either ditto among the different divisions of basketball and soccer players. Based on the data obtained in this study, we concluded that the subjects' body weight have a decisive effect on the production of peak torque values of quadriceps and hamstring muscles in basketball and soccer players. Furthermore that the playing in different divisions, as well as participating in different sports, i.e. basketball or soccer, have surprisingly small effects on the peak isokinetic torque production of the quadriceps and hamstring muscles.
High-speed actions are known to impact soccer performance and can be categorized into actions requiring maximal speed, acceleration, or agility. Contradictory findings have been reported as to the extent of the relationship between the different speed components. This study comprised 106 professional soccer players who were assessed for 10-m sprint (acceleration), flying 20-m sprint (maximum speed), and zigzag agility performance. Although performances in the three tests were all significantly correlated (p , 0.0005), coefficients of determination (r2) between the tests were just 39, 12, and 21% for acceleration and maximum speed, acceleration and agility, and maximum speed and agility, respectively. Based on the low coefficients of determination, it was concluded that acceleration, maximum speed, and agility are specific qualities and relatively unrelated to one another. The findings suggest that specific testing and training procedures for each speed component should be utilized when working with elite players.
Height, mass and skeletal maturity (Fels method) were assessed in 135 elite youth soccer players aged 10.7-16.5 years (only two boys were <11.0 years). Sample sizes, years of training and current weekly training volume by two-year age groups were: 11-12 years (n = 63), 2.6 ± 1.0 years and 4.1 ± 1.7 h; 13-14 years (n = 29), 3.1 ± 1.6 years and 4.5 ± 1.7 h; 15-16 years (n = 43), 4.7 ± 2.4 years and 6.1 ± 2.0 h. The oldest age group included membersof the national youth team.Heights and masses were compared to US reference values,and skeletal age and chronological age were contrasted. The players were also classified as late, average ("on time") and early maturers on the basis of differences between skeletal and chronological age, with the average category including boys with skeletal ages within ± 1 year of chronological age. The mean heights and masses of 11- to 12-year-old soccer players equalled the US reference values, while those of players aged 13-14 and 15-16 years were slightly above the reference values. The mean skeletal age approximated mean chronological age in players aged 11-12 years (12.4 ± 1.3 and 12.3 ± 0.5 years, respectively), while mean skeletal age was in advance of mean chronological age in the two older groups (14.3 ± 1.2 and 13.6 ± 0.7 years, respectively, in 13- to 14-year-olds; 16.7 ± 1.0 and 15.8 ± 0.4 years, respectively, in 15- to 16-year-olds). Seven boys in the oldest age group were already skeletally mature and were not included when calculating differences between skeletal and chronological age. The proportion of late maturing boys in this sample of elite soccer players decreased with increasing chronological age. Among 11- to 12-year-old players, the percentages of late and early maturing boys were equal at 21% (n = 13). Among 13- to 14-year-old players, the percentages of late and early maturing boys were 7% (n = 2) and 38% (n = 11) respectively, while among players aged 15-16 years the percentages of late and early maturing boys were 2% (n = 1) and 65% (n = 28) respectively. The results of this comparative analysis suggest that the sport of soccer systematically excludes late maturing boys and favours average and early maturing boys as chronological age and sport specialization increase. It is also possible that late maturing boys selectively drop-out of soccer as age and sport specialization increase.
The purpose of this study was to test the effect of increased fluid intake on temperature regulation and performance in elite soccer players. Eight players of the Puerto Rico National Team were studied under field conditions at a Wet Bulb Globe Temperature (WBCT) heat stress index of 25.3 ¬± 0.5 ¬?C. They were young (17.0 ¬± 0.6 yr) and well aerobically conditioned, as shown by their maximum aerobic power of 69.2 ¬± 0.7 ml kg-1 min-1 Players were randomly allocated to a week of 'voluntary hydration (VH) (fluid intake = 2.7 ¬± 0.21 day-1) and a week of hyperhydration (HH) (fluid intake = 4.6 ¬± 0.2 l ¬? day-1) (p < 0.05) prior to a soccer match. Their total body water (TBW) increased in HH compared to VH (p < 0.05), despite a significant increase in urine output (p < 0.01). The soccer match was played at 82 ¬± 7 % (VH) and 83 ¬± 6 % (HH) of maximum heart rate. Sweat losses and core temperature increases during the match were similar in both hydration conditions. When the environmental conditions were taken into consideration, the increase in core temperature during the match rose, as a function of the heat stress index, only in VH (p <0.05). Plasma volume was slightly reduced in both hydration conditions (ns). Performance assessment at the end of the soccer match revealed that average time to complete 7 repetitions of a soccer specific test was significantly increased (p < 0.05) after the match in both hydration conditions but showed no difference between them. Peak torque and fatigability of knee flexor and extensor muscle groups at 240 deg sec-1, measured on a Cybex 340 dynamometer, were similar in both hydration conditions and not affected by the soccer match. The data suggest that additional water intake in these heat-acclimated players increased body water reserves and improved temperature regulation during a soccer match with no significant effect on the decrement in soccer specific performance observed at the end of a soccer match.
We test whether attendances in team sports respond positively to the amount of uncertainty of the outcome between the competing teams in a match. Our results show that admissions at English soccer matches relate positively to the quality of teams involved and negatively to a measure of the relative win probabilities of the competing teams. The uncertainty measure is derived from a model of the betting market which corrects for specific biases tested for and identified in the odds in our data set. Although supporters appear to favour an uncertainty of outcome, a greater quality of strength across clubs may still yield a fall in aggregate attendance because of the extent to which home field advantage generates an uneven contest between similarly strong teams.
Purpose: To examine the activity profile and physical loading of elite female soccer players during match play and to study the relationship between training status and physical match performance.
Methods: Time-motion analysis and HR recordings were performed on 14 elite female soccer players during competitive matches. In addition, the players carried out a laboratory treadmill test and the Yo-Yo intermittent recovery test.
Results: The total distance covered during a game was 10.3 km (range: 9.7-11.3) with high-intensity running (HIR) accounting for 1.31 km (0.71-1.70). HIR was performed 125 times (72-159) for 2.3 s (2.0-2.4) on average. The average and peak HR in a game were 167 beats per minute (bpm) (152-186) and 186 (171-205), respectively, corresponding to 87% (81-93) and 97% (96-100) of HRmax. Maximal pulmonary oxygen uptake (VÃáO2max) was 49.4 mL¬?min-1¬?kg-1 (43.4-56.8), and incremental treadmill test (ITT) performance was 4.49 min (3.38-5.17). The Yo-Yo test performance was 1379 m (600-1960). The total distance covered during match play did not correlate with VÃáO2max or ITT performance but correlated with the Yo-Yo test result (r = 0.56, P < 0.05). Significant positive correlations were observed between HIR and VÃáO2max (r = 0.81, P < 0.05), ITT (r = 0.82, P < 0.05), and Yo-Yo test performance (r = 0.76, P < 0.05). No relationship was observed between HRmax during match play and any of the performance measures.
Conclusion: The present study demonstrated that 1) HIR during games varies markedly between elite female soccer players, 2) all players have high HR throughout a competitive game with periods of near-maximal values, 3) the distance covered by HIR during match play is closely related to the physical capacity, and 4) the Yo-Yo intermittent recovery test can be used as an indicator of the physical match performance of elite female players.
Abstract. Mood, as measured by the profile of mood states questionnaire (POMS), salivary cortisol (F) and testosterone (T) levels, and performance were examined in 17 male soccer players 4 times during a season. Soccer players provided three saliva samples when getting up (resting values, 8 a.m.), before breakfast (11.30 a.m.), and between 4.00p.m. and 6.00 p.m. The initial measures were performed 1 day following the start of season training (T1). They were then performed before and after a high-intensity training programme (T2 and T3, respectively) and 16 weeks after T3 (T4). Iceberg profiles of POMS were observed during T1, T2 and T3, which coincided with successful performance. Subsequent decreased performance between T3 and T4 coincided with a decrease in vigor and an increase in tension and depression. Indeed, when the normal nycthemeral rhythm for F was observed (i.e. a decrease from morning until evening at all times; T1–T4), there was seemingly a non-statistical elevation of F on the morning of T3, which only became statistically significant at 11.30 a.m. on T3. In spite of a post-high-intensity training programme (T3) increase in catabolism, the soccer players presented iceberg profiles together with a high percentage of winning. Our results could suggest that in team soccer, a decreased T:F ratio does not automatically lead to a decrease in team performance or a state of team overtraining. It appears that combined psychological and physiological changes during high-intensity training are primarily of interest when monitoring training stress in relation to performance.
Top soccer players do not necessarily have an extraordinary capacity in any of the areas of physical performance. Soccer training is largely based on the game itself, and a common recruitment pattern from player to coach and manager reinforces this tradition. New developments in understanding adaptive processes to the circulatory system and endurance performance as well as nerve and muscle adaptations to training and performance have given rise to more effective training interventions. Endurance interval training using an intensity at 90–95% of maximal heart rate in 3- to 8-minute bouts have proved to be effective in the development of endurance, and for performance improvements in soccer play. Strength training using high loads, few repetitions and maximal mobilisation of force in the concentric mode have proved to be effective in the development of strength and related parameters. The new developments in physical training have important implications for the success of soccer players. The challenge both for coaches and players is to act upon the new developments and change existing training practice.
Fifty-five male soccer players organized in three teams, one high and two lower ranking, were followed prospectively during 1 year to register the rate, type and severity of injuries in highly skilled and low-skilled players. The injury rate of the low-skilled players was significantly higher than that of the better players. The reason for this is that low-skilled players play in more competitions. and this is where injuries tend to occur. When we stratified on game/practice, the low-skilled players' excess risk disappeared and no difference was found in the severity of injuries. Different ways of collecting data in epidemiological studies of soccer are discussed and it is concluded that the most precise and accurate collection of data can only be obtained by direct supervision and examination of soccer players in the field.
Purpose: To investigate the relationship between physical fitness and team success in soccer, and to test for differences in physical fitness between different player positions.
Methods: Participants were 306 male soccer players from 17 teams in the two highest divisions in Iceland. Just before the start of the 1999 soccer season, the following variables were tested: height and weight, body composition, flexibility, leg extension power, jump height, and peak O2 uptake. Injuries and player participation in matches and training were recorded through the 4-month competitive season. Team average physical fitness was compared with team success (final league standing) using a linear regression model. Physical fitness was also compared between players in different playing positions.
Results: A significant relationship was found between team average jump height (countermovement jump and standing jump) and team success (P = 0.009 and P = 0.012, respectively). The same trend was also found for leg extension power (P = 0.097), body composition (% body fat, P = 0.07), and the total number of injury days per team (P = 0.09). Goalkeepers demonstrated different fitness characteristics from outfield players. They were taller and heavier, more flexible in hip extension and knee flexion, and had higher leg extension power and a lower peak O2 uptake. However, only minor differences were observed between defenders, midfield players, and attackers.
Conclusion: Coaches and medical support teams should pay more attention to jump and power training, as well as preventive measures and adequate rehabilitation of previous injuries to increase team success.
Soccer is one of the most widely played sports in the world (15,29) and is a sport characterized by short sprints, rapid acceleration or deceleration, turning, jumping, kicking, and tackling (4,30). It is generally assumed that through the years, the game has developed to become faster, with more intensity and aggressive play than seen previously (29). Elite soccer is a complex sport, and performance depends on a number of factors, such as physical fitness, psychological factors, player technique, and team tactics. Injuries and sequelae from previous injuries can also affect the players' ability to perform.
During a 90-min soccer match an elite player covers on the average between 10 and 11 km per game (4,6,11,20,29). Although the distance covered by different players in the same position varies, studies have shown that midfielders travel farther than defenders or attackers, probably because of their linking role in the team (6,11,29). Among the defensive players, the fullbacks usually cover more distance than centerbacks, since they are usually more involved during the attacking phase. Although most of the movement for all players is at low or submaximal intensity (6,21,29), it has been estimated that the mean work rate is about 70-75% of maximum oxygen uptake and close to the anaerobic threshold (6,20,21). Midfield players cover a greater percentage of their distance at lower intensity, whereas attackers cover a greater proportion at a sprint (11,29). This indicates that there may be a difference in the requirements between different playing positions, but whether this is reflected by differences in fitness is not clear (6,10,30).
Studies on the physical performance of elite soccer players indicate that the average maximal O2 uptake ranges between 56.8 and 67.6 mL¬?kg-1¬?min-1 (1,5,6,8,10,22,27,30), whereas mean body fat (%) is between 8.6 and 11.2% (8,10,22,27). Muscular power has mainly been reported as jump height, using different tests. Some studies have found a vertical jump of 55.6-63.4 cm (27,28), whereas other studies reported a countermovement jump height of 41.4-41.6 cm and a standing jump height of 38.5-39.0 cm (8,9). Flexibility, muscle strength and hamstring to quadriceps strength ratios among soccer players have also been reported in several studies, but methodological differences (test type, speed, joint angle, etc.) make direct comparisons difficult (9,10,18,19).
Although one might expect team success to be strongly correlated to physical fitness, there is limited evidence for such a relationship. One study found a correlation between the amount of training and the training to match ratio on one side and team success on the other (12). Wisloff et al. (30) compared the fitness of one team at the top and another at the bottom of the Norwegian elite division and found that the best team had significantly higher test values for maximal O2 uptake and 1-RM squat. However, an obvious limitation of this study was that only two teams were compared, and we therefore wanted to expand their approach by including the teams of two divisions in Icelandic soccer. The aim was to study the relationship between physical fitness and team performance by comparing various indices of physical fitness between and within divisions with final league standing. We also wanted to test for differences in physical fitness between different player positions.
Soccer is an endurance sport that consists of moderate activity levels interspersed with intermittent high-intensity bursts, leading to high rates of metabolic heat production. Even when the weather is cold, significant sweat loss will occur, leading to a degree of dehydration which impairs exercise performance. Fluid intake before and during the game will provide water to reduce the degree of dehydration and can also supply carbohydrate to supplement the body's limited carbohydrate stores. Dilute carbohydrate-electrolyte drinks are most effective for rehydration. The optimum formulation will vary between individuals and will also depend on climatic conditions. Players should be encouraged to experiment with fluid intake during training to identify the type of drink and the amount and frequency of drinks that best meet their needs.
Although the physical demands of soccer have been studied frequently over the years, there has been little attention to the dietary protein needs of soccer players. Recent data from both moderate-intensity, prolonged (endurance) and heavy-resistance (strength) exercise studies indicate that the current recommendations (0.8 g per kg body mass per day) for protein intake are probably suboptimal for individuals who are chronically active. Endurance athletes need more dietary protein than sedentary individuals to maintain an auxiliary fuel source which appears to become increasingly important as exercise is prolonged. Strength athletes can also benefit from a greater protein intake than is currently recommended because it appears that, in combination with heavy-resistance training, it can provide an enhanced stimulus for muscle development. Soccer is a high-intensity, intermittent activity which requires aspects of both strength and endurance over a period of 90 min. As a result, soccer players would be likely to benefit from protein intakes above current recommendations not only because of their potential to enhance strength, but also to provide a supply of amino acids for any increased amino acid oxidation that may occur during training and in competition. Based on the related exercise studies completed to date, it appears that a protein intake of 1.4-1.7 g kg-1 day-1 should be adequate for soccer players. Assuming free access to a wide variety of foods, this protein intake can be easily obtained by most soccer participants. Individuals at greatest risk of falling short of this intake include those who are growing (especially children in developing countries where suboptimal protein intake may be common) or those who consume proteins of lower quality. Although diets high in protein are frequently condemned because of possible kidney problems, it appears these concerns have been over-emphasized. There is no evidence that protein intakes in the range recommended will cause healthy individuals any concerns.
Purpose: To examine muscle and blood metabolites during soccer match play and relate it to possible changes in sprint performance.
Methods: Thirty-one Danish fourth division players took part in three friendly games. Blood samples were collected frequently during the game, and muscle biopsies were taken before and after the game as well as immediately after an intense period in each half. The players performed five 30-m sprints interspersed by 25-s recovery periods before the game and immediately after each half (N = 11) or after an intense exercise period in each half (N = 20).
Results: Muscle lactate was 15.9 ¬± 1.9 and 16.9 ¬± 2.3 mmol¬?kg-1 d.w. during the first and second halves, respectively, with blood lactate being 6.0 ¬± 0.4 and 5.0 ¬± 0.4 mM, respectively. Muscle lactate was not correlated with blood lactate (r2 = 0.06-0.25, P >0.05). Muscle glycogen decreased (P < 0.05) from 449 ¬± 23 to 255 ¬± 22 mmol¬?kg-1 d.w. during the game, with 47 ¬± 7% of the muscle fibers being completely or almost empty of glycogen after the game. Blood glucose remained elevated during the game, whereas plasma FFA increased (P < 0.05) from 0.45 ¬± 0.05 to 1.37 ¬± 0.23 mM. Mean sprint time was unaltered after the first half, but longer (P < 0.05) after the game (2.8 ¬± 0.7%) as well as after intense periods in the first (1.6 ¬± 0.6%) and second halves (3.6 ¬± 0.5%). The decline in sprint performance during the game was not correlated with muscle lactate, muscle pH, or total glycogen content.
Conclusion: Sprint performance is reduced both temporarily during a game and at the end of a soccer game. The latter finding may be explained by low glycogen levels in individual muscle fibers. Blood lactate is a poor indicator of muscle lactate during soccer match play.
The relationship between quadriceps muscle temperature (Tm) and sprint performance was evaluated during soccer matches in 25 competitive players. In one game, Tm was determined frequently (n=9). In another game, eight players performed low-intensity activities at half-time (re-warm-up, (RW), whereas another eight players recovered passively (CON). Tm was 36.0¬±0.2 ¬?C at rest and increased (P<0.05) to 39.4¬±0.2 ¬?C before the game and remained unaltered during the first half. At half-time, Tm decreased (P<0.05) to 37.4¬±0.2 ¬?C, but increased (P<0.05) to 39.2¬±¬?C during the second half. In CON and RW, Tm and core temperature (Tc) were similar before and after the first half, but 2.1¬±0.1 and 0.9¬±0.1 ¬?C higher (P<0.05), respectively, in RW prior to the second half. At the onset of the second half, the sprint performance was reduced (P<0.05) by 2.4% in CON, but unchanged in RW. The decrease in Tm was correlated to the decrease in performance (r=0.60, P<0.05, n=16). This study demonstrates that in soccer, the decline in Tm and Tc during half-time is associated with a lowered sprint capacity at the onset of the second half, whereas sprint performance is maintained when low-intensity activities preserve muscle temperature.
The purpose of this study was to examine the effects of different modes of stretching within a pre-exercise warm-up on high-speed motor capacities important to soccer performance. Eighteen professional soccer players were tested for countermovement vertical jump, stationary 10-m sprint, flying 20-m sprint, and agility performance after different warm-ups consisting of static stretching, dynamic stretching, or no stretching. There was no significant difference among warm-ups for the vertical jump: mean +/- SD data were 40.4 +/- 4.9 cm (no stretch), 39.4 +/- 4.5 cm (static), and 40.2 +/- 4.5 cm (dynamic). The dynamic-stretch protocol produced significantly faster 10-m sprint times than did the no-stretch protocol: 1.83 +/- 0.08 seconds (no stretch), 1.85 +/- 0.08 seconds (static), and 1.87 +/- 0.09 seconds (dynamic). The dynamic- and static-stretch protocols produced significantly faster flying 20-m sprint times than did the nostretch protocol: 2.41 +/- 0.13 seconds (no stretch), 2.37 +/- 0.12 seconds (static), and 2.37 +/- 0.13 seconds (dynamic). The dynamic-stretch protocol produced significantly faster agility performance than did both the no-stretch protocol and the staticstretch protocol: 5.20 +/- 0.16 seconds (no stretch), 5.22 +/- 0.18 seconds (static), and 5.14 +/- 0.17 seconds (dynamic). Static stretching does not appear to be detrimental to high-speed performance when included in a warm-up for professional soccer players. However, dynamic stretching during the warm-up was most effective as preparation for subsequent high-speed performance.
The effect on muscle glycogen utilization of drinking a glucose polymer solution before and during a soccer match was studied. Ten male soccer players were divided into two groups balanced both for playing position and between the two teams. Five players on the experimental team (ET) ingested 0.5 L of 7% glucose polymer solution 10 min before the game and at half-time. Five control team (CT) players ingested equal volumes of placebo at the same times. The players were biopsied in the vastus lateralis before and after the game. The change in muscle glycogen was less (p less than 0.01) in ET (111 +/- 24 mmol glucose units.kg-1 dry muscle) than in CT (181 +/- 24 mmol.kg-1). Blood glucose concentration was not changed after the game in either group. This study demonstrates that glucose ingestion reduces net muscle glycogen utilization in a field setting, i.e. soccer match play.
The myosin heavy chain (MHC) composition of single fibres (n = 2171) was analysed with an electrophoretic technique in biopsy material from m. vastus lateralis of two groups of soccer players before and after a 3-month period of either strength- (n = 8) or non-training (control) (n = 6). Traditional myofibrillar ATPase histochemistry demonstrated a decrease in type IIA fibres with strength-training (35.4 ± 2.1 vs. 26.7 ± 2.4% (P < 0.05)). This was not observed in the non-training group (25.7 ± 4.6 vs. 23.8 ± 1.7%). One-dimensional electrophoresis on muscle homogenates showed no significant change in the amount of MHC isoforms in either of the two groups. The MHC isoform I IB was undetectable in all but three samples. No changes in the proportions of fibres containing any of the MHC isoforms were observed. Fibres containing only MHC isoform I IB were found in very small numbers (only 11 out of 2171). Before the experimental period, between 6 and 10% histochemical type IIB fibres were found in both groups. This was identical with the proportion of fibres showing co-existence of MHC isoforms IIA and IIB, but in contrast to the very few fibres containing only MHC isoform IIB. This suggests that nearly all histochemical type IIB fibres of the soccer players display co-existence of both MHC isoform IIA and IIB. No major change in the muscle fibre area of the two groups was observed. The strength-training group increased mean power output in a short-term dynamic knee-extensor test after strength-training (119 ± 6.6 vs. 136.5 ± 4.7 W (P < 0.01)), whereas no change was observed in the non-training group (151.2 ± 4.5 vs. 148.4 ± 6.5 W).
The aim of this study was to determine the effect of carbohydrate (CHO) versus placebo (PLA) beverage consumption on the immune and plasma cortisol responses to a soccer-specific exercise protocol in 8 university team soccer players. In a randomized, counterbalanced design, the players received carbohydrate or placebo beverages before, during and after two 90min soccer-specific exercise bouts (3 days apart) designed to mimic the activities performed and the distance covered in a typical soccer match. Blood and saliva samples were collected before, during and after the exercise protocol. Plasma lactate concentration increased to ~4 mmol.l-1 at 45 and 90 min of exercise in both treatments (P< 0.01). Plasma glucose concentration was significantly lower after 90 min of exercise with ingestion of the placebo than the carbohydrate (PLA: 4.57 +/- 0.12 mmol.l-1; CHO: 5.49 +/- 0.11 mmol.l-1; P< 0.01). The pattern of change in plasma cortisol, circulating lymphocyte count and saliva immunoglobulin A secretion did not differ between the carbohydrate and placebo trials. Blood neutrophil counts were 14% higher 1 h after the placebo trial than the carbohydrate trial (PLA: 4.8 =/- 0.5 x 10 9 cells.l-1; CHO:4.2 +/- 0.5 x 10 9 cells.l-1; P=0.06),but the treatment had no effect on the degranulation response of blood neutrophils stimulated by bacterial lipopolysaccharide. We conclude that, although previous studies have shown that carbohydrate feeding is effective in attenuating immune responses to prolonged continuous strenuous exercise, the same cannot be said for a soccer-specific intermittent exercise protocol. When overall exercise intensity is moderate,and changes in plasma glucose, cortisol and immune variables are relatively small, it would appear that carbohydrate ingestion has only a minimal influence on the immune response to exercise.
To cope with the physiological demands of soccer, players must be competent across several fitness components. The use of fitness tests in the laboratory and field assist in examining soccer players' capabilities for performance both at the amateur and elite levels. Laboratory tests provide a useful indication of players' general fitness. Accurate test results can be obtained with the use of a thorough methodology and reliable equipment. Laboratory tests are used sparingly during the season because of the time-consuming nature of the tests. Instead, tests are generally carried out at the start and end of the pre-season period to evaluate the effectiveness of specific training interventions. Field tests provide results that are specific to the sport and are therefore more valid than laboratory tests. The reduced cost, use of minimal equipment and the ease with which tests can be conducted make them more convenient for extensive use throughout the season. Although data from laboratory and field tests provide a good indication of general and soccer-specific fitness, individual test results cannot be used to predict performance in match-play conclusively because of the complex nature of performance in competition. Fitness tests in conjunction with physiological data should be used for monitoring changes in players' fitness and for guiding their training prescription.
Background. Soccer reportedly places participants at risk for neuropsychological impairment, although it is unknown if the risk is associated primarily with concussion, subconcussive blows from heading the ball, or some combination thereof. Moreover, the extent to which younger versus older athletes are at risk for soccer-related cognitive impairment is unclear. We hypothesized that soccer athletes, especially older ones, would show poorer neuropsychological test performance than comparable swimmers. Methods. Thirty-two soccer (26 college and 6 professional) and 29 swimmers (22 college and 7 masters level), all involved for at least 4 years in their sport at collegiate or national levels, participated. In a 2 X 2 (sport X age category) factorial design, all participants underwent 4 neuropsychological tests with 11 outcome measures assessing motor speed, attention, concentration, reaction time, and conceptual thinking. Results. Soccer athletes performed worse than swimmers on measures of conceptual thinking. The older soccer group in particular performed poorly on measures of conceptual thinking, reaction time, and concentration. Among non-goaltender soccer athletes, estimates of career exposure to brain trauma (based on length of career and level of play) predicted significantly poorer test performance on 6 of 11 measures, even after statistically controlling for age. Conclusions. Results provide additional evidence that participation in soccer may be associated with poorer neuropsychological performance, although the observed pattern of findings does not specifically implicate heading as the cause. Although deficits were most apparent among older soccer players, serial neuropsychological testing for early detection of impairment is recommended for younger players as well.
Abstract This cross-sectional study investigated bone mass in female athletes participating in an impact-loading sport (soccer), and evaluated whether any changes in bone mass could be related to the type of weight-bearing loading and muscle strength. The group of soccer players consisted of 16 second-division female players (age 20.9±2.2 years) training for about 6 hours/week. The reference group consisted of 13 nonactive females (age 25.0±2.4 years) not participating in any kind of regular or organized sport activity. The groups were matched according to weight and height. Areal bone mineral density (BMD) was measured in total body, head, lumbar spine, femoral neck, Ward's triangle, trochanter, the whole femur and humerus, and in specific sites in femur diaphysis, distal femur, proximal tibia, and tibia diaphysis using dual X-ray absorptiometry. Isokinetic concentric peak torque of the quadriceps and hamstring muscles was measured using an isokinetic dynamometer. The soccer players had significantly (P<0.05-0.01) higher BMD in the lumbar spine (10.7%), femoral neck (13.7%), Ward's triangle (19.6%), nondominant femur and humerus (8.2 and 8.0%, respectively), distal femur (12.6%), and proximal tibia (12.0%) compared with the nonactive women. There was no significant difference in muscle strength of the thigh between the two groups. In the nonactive group, muscle strength in the quadriceps and especially hamstrings, was correlated to BMD of the adjacent bones (whole femur, hip sites) and also to distant sites (humerus). In the soccer group, there were no correlations between muscle strength and BMD of the adjacent and distant bones. Soccer playing and training appears to have a beneficial effect on bone mass in young females, and it seems that there is a site-specific skeletal response to the type of loading subjected to each BMD site. Muscle strength in the thigh is not related to bone mass in female soccer players.
The paper provides a large-scale study into the motion characteristics of top class soccer players, during match play, according to playing position. Three hundred top-class outfield soccer players were monitored during 20 Spanish Premier League and 10 Champions League games using a computerized match analysis system (Amisco Pro, Nice, France). Total distance covered in five selected categories of intensity, and the mean percentage of playing time spent in each activity were analyzed according to playing position. Midfield players covered a significantly greater total distance (p < 0.0001) than the groups of defenders and forwards did. Analyzing the different work rates showed significant differences (p < 0.5 - 0.0001) between the different playing positions. There were no significant differences between halves in the total distance covered, or in distances covered at submaximal and maximal intensities. However, significantly more distance was covered in the first half compared to the second in medium intensities (11.1 - 19 km/h). The current findings provide a detailed description of the demands placed on elite soccer players, according to their positional role at different work intensities, which may be helpful in the development of individualized training programs.
The purposes of this study were to assess the aerobic and anaerobic characteristics of Saudi elite soccer players, and to examine the interrelationship between measures of aerobic and anaerobic power in the elite soccer players. 23 outfield elite soccer players representing the Saudi national team participated. Their means (±SD) for age, body mass, height and estimated fat % were: 25.2±2.3 years; 73.1±6.8 kg; 177.2±5.9 cm; and 12.3±2.7%, respectively. Cardiorespiratory parameters, including maximal oxygen uptake (VO2max), were assessed by open-circuit spirometry during graded treadmill running. Anaerobic power measures were obtained using Wingate anaerobic test, and included peak power (PP), and average power for 5 sec (AP 5), 10 sec (AP 10), 20 sec (AP 20) and 30 sec (AP 30). Results showed that mean (±SD) values for VO2max in absolute and relative to body mass were 4.16±0.34 l.min-1 and 56.8±4.8 ml.kg-1.min-1, respectively. Such VO2max value was 118% and 80% of those reported for Saudi college males and distance runners, respectively. The ventilatory anaerobic threshold (Tvent) averaged 43.6 ml.kg-1.min-1. There were no significant differences in VO2max and Tvent between players based on positions, although the midfielders and the centre-backs had the highest and the lowest individual values for both measures, respectively. Values (±SD) of PP and AP 30 were 873.6±141.8 W (11.88±1.3 W.kg-1), and 587.7±55.4 W (8.02±0.53 W.kg-1), respectively. Only in absolute PP & AP 30 were the centre-backs significantly superior to the other players. In addition, VO2max was inversely related to PP (r=-0.54; p<0.05) and positively related to AP 30 (r=0.45; p<0.05). It is concluded that the aerobic power, expressed relative to body mass, of Saudi elite soccer players was in the lower range of values normally reported in the literatures for elite soccer players. Both PP and AP 30 were somewhat lower than values previously reported for elite soccer players from other countries.
Twenty-five collegiate soccer players were evaluated for lower extremity flexibility and muscle strength at the end of preseason training and before the onset of the collegiate soccer season on two successive seasons. The purpose of the evaluation was to determine whether symmetry was present in their legs and whether deficits in flexibility or strength would affect the susceptibility to hamstring or groin muscle strain injuries. The mean (+/- SE) flexibility of the dominant leg for hip abduction was 41 degrees +/- 1.2 degree; for hip flexion, 76 degrees +/- 1.9 degree; for hip extension, 174 degrees +/- 0.7 degree; and for ankle dorsiflexion, 33 degrees +/- 1.3 degree. The mean (+/- SE) isokinetic torque of the dominant leg (tested at 30 degrees per second) for knee extension was 214 +/- 8 newton meters and for flexion was 128 +/- 4 newton meters, while isometric strength for hip flexion was 315 +/- 8 newtons and for ankle plantar flexion was 1721 +/- 58 newtons. No significant differences were found between the dominant and nondominant legs in flexibility or strength. During this study no hamstring or groin strain injuries occurred. The lack of leg muscle strain injuries appeared to be directly related to the initiation of a controlled warmup and stretching program and underlines the importance of this in injury prevention. Interestingly, more than 50% (13 of 25) of the players were found to have significant deficits in one or more specific muscle groups. Two athletes sustained low back strain injuries and one athlete had a knee sprain injury.(ABSTRACT TRUNCATED AT 250 WORDS)
Aim: To determine if there are correlations between the physical fitness of young soccer players assessed by field and laboratory testing.
Methods: Thirty four male soccer players took part in the study (mean (SD) age 17.5 (1.1) years, height 177.8 (6.7) cm, weight 70.5 (6.4) kg). Maximal oxygen uptake (Vo2max) during treadmill running and vertical jump height on a force platform were measured in the laboratory. Field tests consisted of a soccer specific endurance test (Bangsbo test) and 30 m sprint with 10 m lap times.
Results: The Bangsbo test correlated with the lowest velocity associated with Vo2max (vVo2max; R2‚Ää=‚Ää 0.55, p<0.001), but not with Vo2max. Sprint times at 30 m and 20 m were related to peak extension velocity and peak extension force measured during vertical jumping, but not to vertical jump height per se. The jumping force and velocity could explain 46% of the 30 m sprint performance (R2‚Ää=‚Ää 0.46, p<0.001).
Conclusion: The Bangsbo test and 30 m sprint test correlate with vVo2max and vertical jump force and velocity respectively. The Bangsbo test does not give a good estimate of Vo2max in young soccer players.
The purpose of this study was to assess the effects of soccer training on strength and power of leg extensor muscles in preadolescent boys and their possible influence in developing a muscular lateral dominance. Twenty male children (mean age 9.6 yr), ten soccer players and ten untrained subjects, participated in this study. Force and power were measured at five constant cranking velocities on an isokinetic bicycle dinamometer. Each isokinetic load was given after each trial. Force and power outputs were calculated for each limb. Soccer players always showed higher and statistically significant differences (p < 0.05) for force and power values for all considered pedal frequencies. No significant differences were observed for force and power values between preferred and non preferred limb. The results demonstrate the effect of soccer training on the increase of force and power of both legs regardless of lateral dominance.
Isometric and functional strength of ninety-eight 11-yr-old male soccer players at an elite (E) and nonelite (NE) level were determined (3-4 times) through a 2-yr period, and the changes were related to growth and maturation. The initial isometric strength for extension with dominant leg [1,502 ± 35 (E) vs. 1,309 ± 39 (NE) N], extension with nondominant leg (1,438 ± 37 vs. 1,267 ± 45 N), extension with both legs (2,113 ± 76 vs. 1,915 ± 72 N), back muscles (487 ± 11 vs. 414 ± 10 N), abdominal muscles (320 ± 9 vs. 294 ± 8 N), and handgrip (304 ± 10 vs. 259 ± 8 N) increased by 15-40% during the period. Broad jump increased (P < 0.05) by 15 (E) and 10% (NE). The E players had higher (P < 0.05) initial isometric strength and broad jump performance compared with NE players, and differences were maintained throughout the period (multiple ANOVA for repeated measures) also when adjustment was made for age, dimensions, testosterone, and insulin-like growth factor I (generalized estimating equations analyses). The development of strength for both E and NE players together was significantly (P < 0.001) related to changes in serum testosterone concentrations. The present data indicate that testosterone is important for development of strength in young boys and that, independent of serum testosterone concentration, E players have developed greater muscle strength compared with NE players.
This review summarizes results from studies investigating the physical characteristics, daily energy expenditures, diets, and effects of nutritional supplements to the habitual diets of soccer players. The results show that players fall within a wide range of stature and body weight, and they are classified as mesomorphs. The body fat of male players is about 10% of body weight, whereas the average for females is about 21%. Energy expenditure for males is about 4,000 kcal on training days and 3,800 kcal on match day, while energy intake reported in other studies is on the order of 3,700 kcal. Carbohydrate (CHO), fat, and protein intakes are about 53, 30, and 14% of energy intake, respectively, the remaining being from alcohol intake. There are indications that CHO supplements might be beneficial during soccer performance. However, more research is needed to clarify the importance of branched-chain amino acid and creatine supplementation in soccer.
Background: Improved oxygen uptake improves soccer performance as regards distance covered, involvements with the ball, and number of sprints. Large improvements in oxygen uptake have been shown using interval running. A similar physiological load arising from interval running could be obtained using the soccer ball in training.
Objectives: The main aim was to study physiological adaptations to a 10 week high intensity aerobic interval training program performed by professional youth soccer players, using a soccer specific ball dribbling track.
Methods: Eleven youth soccer players with a mean (SD) age of 16.9 (0.4) years performed high intensity aerobic interval training sessions twice per week for 10 weeks in addition to normal soccer training. The specific aerobic training consisted of four sets of 4 min work periods dribbling a soccer ball around a specially designed track at 90–95% of maximal heart frequency, with a 3 min recovery jog at 70% of maximal heart frequency between intervals.
Results: Mean Vo2max improved significantly from 63.4 (5.6) to 69.8 (6.6) ml kg‚àí1 min‚àí1, or 183.3 (13.2) to 201.5 (16.2) ml kg‚àí0.75 min‚àí1 (p<0.001). Squat jump and counter movement jump height increased significantly from 37.7 (6.2) to 40.3 (6.1) cm and 52.0 (4.0) to 53.4 (4.2) cm, respectively (p<0.05). No significant changes in body mass, running economy, rate of force development, or 10 m sprint times occurred.
Conclusion: Performing high intensity 4 min intervals dribbling a soccer ball around a specially designed track together with regular soccer training is effective for improving the Vo2max of soccer players, with no negative interference effects on strength, jumping ability, and sprinting performance.
Comparison of the kinematics of the full-instep and pass kicks in soccer. Med. Sci. Sports Exerc., Vol. 30, No. 6, pp. 917-927, 1998.
Purpose: The goal of this study was to gain a better understanding of the mechanics of the inside-of-the-foot passing shot used in soccer ("pass kick").
Methods: The motions of the pass kick were compared with those of the full-instep kick ("full kick"). The study followed an inverse dynamics approach, using three-dimensional cinematographic techniques.
Results: At impact, the pelvis and the thigh-shank plane pointed more toward the right in the pass kick; the shank-foot plane also pointed further outward relative to the thigh-shank plane. Knee extension accounted for most of the speed of the foot in both kicks (86% in the full kick; 67% in the pass kick). In the pass kick, pelvis tilt toward the right and hip adduction contributed to a medial component of foot velocity (8.4 m¬?s-1) normal to the thigh-shank plane, which made the resultant foot velocity vector more oblique to the plane than in the full kick. This facilitated ball impact with the medial aspect of the foot. The slower ball speed in the pass kick was because of a slower foot speed (18.3 m¬?s-1 vs 21.6 m¬?s-1). Limitations in the maximum medial velocity that can be generated may force players to restrain the within-plane (and therefore also the resultant) velocity of the foot to be able to impact the ball squarely with the medial aspect of the foot.
Conclusions: To impact the ball with the medial aspect of the foot in the pass kick, the player orients the pelvis, the right leg, and the foot more toward the right and introduces a medial component of foot velocity. However, most of the speed of the foot is still generated through knee extension.
This study examined the nutritional and performance status of elite soccer players during intense training. Eight male players (age 17 +/- 2 years) of the Puerto Rican Olympic Team recorded daily activities and food intake over 12 days. Daily energy expenditure was 3,833 +/- 571 (SD) kcal, and energy intake was 3.952 +/- 1,071 kcal, of which 53.2 +/- 6.2% (8.3 g (.) kg BW(-1)) was from carbohydrates (CHO), 32.4 +/- 4.0% from fat, and 14.4 +/- 2.3% from protein. With the exception of calcium, all micronutrients examined were in accordance with dietary guidelines. Body fat was 7.6 +/- 1.1% of body weight. Time to completion of three runs of the soccer-specific test was 37.65 +/- 0.62 s, and peak torques of the knee flexors and extensors at 60 degrees (.) s(-1) were 139 +/- 6 and 225 +/- 9 N (.) m, respectively. Players' absolute amounts of CHO seemed to be above the minimum recommended intake to maximize glycogen storage, but calcium intakes were below recommended. Their body fat was unremarkable, and they had a comparatively good capacity to endure repeated bouts of intense soccer-specific exercise and to exert force with their knee extensors and flexors.
Two experiments examined whether 12 experienced soccer players would exhibit greater task-specific cognitive knowledge than would 12 inexperienced players. Ss viewed structured and unstructured soccer action sequences on a video projection screen. In recalling specific player positions following brief (10-sec) film clips, inexperienced Ss had larger recall of errors than did experienced Ss on structural trials only. This finding indicates that experienced Ss' cognitive knowledge permitted more meaningful associations between players' positions, resulting in more efficient retrieval. When recognition of previously viewed film clips was examined, experienced Ss were more accurate in recognizing structured trials only. Experienced soccer players seem to have a more complex and discriminating organization of long-term memory that facilitates the encoding of task-specific information. (PsycINFO Database Record (c) 2009 APA, all rights reserved)
Twice as many top soccer players from The Netherlands, Belgium and France are born in August, as compared to July. A creeping selection mechanism, inadvertently caused by organisational aspects of the youth soccer competition in the countries mentioned, could be the explanation.
The aim of this study was to examine the effects of exercise type, field dimensions, and coach encouragement on the intensity and reproducibility of small-sided games. Data were collected on 20 amateur soccer players (body mass 73.1 ¬± 8.6 kg, stature 1.79 ¬± 0.05 m, age 24.5 ¬± 4.1 years, VÀôO2max 56.3 ¬± 4.8 ml ¬? kg-1 ¬? min-1). Aerobic interval training was performed during three-, four-, five- and six-a-side games on three differently sized pitches, with and without coach encouragement. Heart rate, rating of perceived exertion (RPE) on the CR10-scale, and blood lactate concentration were measured. Main effects were found for exercise type, field dimensions, and coach encouragement (P < 0.05), but there were no interactions between any of the variables (P > 0.15). During a six-a-side game on a small pitch without coach encouragement, exercise intensity was 84 ¬± 5% of maximal heart rate, blood lactate concentration was 3.4 ¬± 1.0 mmol ¬? l-1, and the RPE was 4.8. During a three-a-side game on a larger pitch with coach encouragement, exercise intensity was 91 ¬± 2% of maximal heart rate, blood lactate concentration was 6.5 ¬± 1.5 mmol ¬? l-1, and the RPE was 7.2. Typical error expressed as a coefficient of variation ranged from 2.0 to 5.4% for percent maximal heart rate, from 10.4 to 43.7% for blood lactate concentration, and from 5.5 to 31.9% for RPE. The results demonstrate that exercise intensity during small-sided soccer games can be manipulated by varying the exercise type, the field dimensions, and whether there is any coach encouragement. By using different combinations of these factors, coaches can modulate exercise intensity within the high-intensity zone and control the aerobic training stimulus.
Little published data describe the dietary and physiological profiles of intercollegiate female soccer players; therefore, the purpose of this investigation was to report baseline dietary data, anthropometrics, and performance indices of soccer women during rigorous pre-season training (2 sessions/day) and then during the post-competitive season. Members of a NCAA Division I women's soccer squad completed 3-day diet records, anthropometrics, and physical tests, including VO2peak. Average body mass was 62 kg with 16% body fat, and no significant pre to post differences were observed. Total energy, carbohydrate (CHO), protein, and fat intakes were significantly greater during the pre-season. Pre-season energy intake met the DRI for females with an "active" lifestyle (37 kcal/kg). While CHO intake failed to meet minimum recommendations to promote glycogen repletion (7-10 g/kg), protein and fat intakes were above minimum recommendations. Pre- and post-season intakes of several micronutrients were marginal (<75% of the DRI) including vitamin E, folate, copper, and magnesium. VO2peak significantly improved from pre- to post-season (42 and 50 ml/kg/min). In this study female soccer players appeared to meet caloric needs during periods of training but failed to meet minimum CHO and micronutrient recommendations. Foods higher in protein and fat displaced more CHO-rich and nutrient-dense foods within athletes' energy requirements and satiety limits.
Abstract Whole-body cooling prior to activity has the potential to reduce thermal strain and fatigue during subsequent endurance exercise. Intermittent activity is associated with greater increases in rectal temperature compared with continuous exercise. Thus, the effect of pre-cooling on thermoregulatory responses was examined during an intermittent test under ‚Äúnormal‚Äù environmental conditions. Six male university soccer players [mean (SD) age 27‚Äâ(2) years; height 1.77‚Äâ(0.3)‚Äâm; mass 72.2‚Äâ(1.5)‚Äâkg; maximal oxygen consumption 58.9‚Äâ(3.5) ml‚Äâ¬?‚Äâkg‚àí1‚Äâ¬?‚Äâmin‚àí1] completed a 90-minute soccer-specific intermittent exercise protocol on a non-motorised treadmill. The run was completed with and without pre-cooling under normal laboratory conditions (20¬?C) and without pre-cooling in a heated laboratory (26¬?C). The pre-cooling strategy involved exposure to a cold shower (26¬?C) for 60‚Äâmin. The pre-cooling manipulation lowered rectal temperature prior to exercise [‚àí0.6‚Äâ(0.6)¬?C, range ‚àí1.5¬?C; P‚Äâ <‚Äâ0.05]. The rectal temperature response to exercise was significantly lower following pre-cooling than in the heated condition [pre-cooled 38.1‚Äâ(0.6)¬?C, heated 38.6‚Äâ(0.3)¬?C]. The increase in rectal temperature during the second half of the protocol following pre-cooling was significantly greater than the increase observed under normal or heated conditions (P‚Äâ <‚Äâ0.05). No significant differences were observed between the three conditions for oxygen consumption, heart rate, minute ventilation, rating of perceived exertion and plasma lactate, glucose or free fatty acid concentrations. Based on the current investigation, it can be concluded that there is no evidence for the beneficial effects of pre-cooling on the physiological responses to soccer-specific intermittent exercise under normal environmental conditions.
The total skeletal bone mineral content (BMC), bone mineral density (BMD), bone size, and body composition were measured by dual-energy x-ray absorptiometry (DXA) in all professional male football players of a 1st division team (n = 24) and age- and BMI-matched (n = 22) controls (less than 3 hours of recreational sport activities per week). Average (±1 SD) age of the athletes was 22.6 ± 2.5 years. Intensive training is conducted during 48 weeks a year for 20–22 hours/week. The length of the registered playing career before the study was 8.2 ± 2.7 years. Total skeleton BMC was 18.0% (P < 0.001) greater in the football players. The difference resulted from the sum of 5.2% (P < 0.02) increment of bone size and 12.3% (P < 0.001) increment of BMD. The analysis of skeletal subareas revealed that the difference of the BMC and BMD was greater at the level of the pelvis and legs compared with the arms or trunk. The BMC and BMD of the head was equal for both groups. Also, the bone size of the legs and pelvis was significantly greater for the players compared with controls; there was no difference at the level of the arms or head. Within the group of football players the increment of total skeleton BMD was similar in the young players, with less than 7 years of practice (age 20.6 ± 0.9 years) compared with relative older players (age 24.6 ± 1.9) with more than 7 years of practice. Lean body mass was significantly greater in the players (63.3 ± 4.0 kg) compared with the controls (56.7 ± 3.6, P < 0.001) whereas fat mass was markedly lower (9.4 ± 2.9 kg versus 14.9 ± 6.3 kg), P < 0.002). The BMD of the controls was significantly correlated to total weight, height, and lean mass whereas the BMD of the players was only correlated to muscle mass. The calcium intake from dairy products was similar in both groups. The range of calcium intake was wide among the players (184–2519 mg/day) but it was not significantly correlated to BMD (r = 0.03). In conclusion, male professional football players develop a significant increment of BMC as a result of increased bone size and density. This is already present at the end of the second decade and maintained at least to the end of the third decade in active players. As in other high impact loading sports, the effect on area is specific involving mainly the pelvis and legs. The increment was totally unrelated to the calcium intake from dairy products. The fate of the increased BMC after intensive training is discontinued should be assessed. However, if the findings of the present cross-sectional study are supported by detailed longitudinal investigations, the presently reported observations might be important for the prevention of future osteoporotic fractures.
As a consequence of the physiological demands experienced during a competitive soccer season, the antagonistic relationship between anabolic and catabolic processes can affect performance. Twenty-five male collegiate soccer players were studied throughout a season (11 weeks) to investigate the effects of long-term training and competition. Subjects were grouped as starters (S; n = 11) and nonstarters (NS; n = 14). Measures of physical performance, body composition, and hormonal concentrations (testosterone [T] and cortisol [C]) were assessed preseason (T1) and 5 times throughout the season (T2-T6). Starters and NS participated in 83.06% and 16.95% of total game time, respectively. Nonstarters had a significant increase ( + 1.6%) in body fat at T6 compared to T1. Isokinetic strength of the knee extensors (1.05 rad-sec-1) significantly decreased in both S (-12%) and NS (-10%; p > 0.05) at T6. Significant decrements in sprint speed ( + 4.3%) and vertical jump (-13.8%) were found at T5 in S only. Though within normal ranges (10.4-41.6 nmol-L-1), concentrations of T at T1 were low for both groups, but increased significantly by T6. Concentrations of C were elevated in both groups, with concentrations at the high end of the normal range (normal range 138-635 nmol-L-1) at T1 and T4 in NS and T4 in S, with both groups remaining elevated at T6. Data indicate that players entering the season with low circulating concentrations of T and elevated levels of C can experience reductions in performance during a season, with performance decrements exacerbated in starters over nonstarters. Soccer players should therefore have a planned program of conditioning that does not result in an acute overtraining phenomenon prior to preseason (e.g., young players trying to get in shape quickly in the 6 to 8 weeks in the summer prior to reporting for preseason camp). The detrimental effects of inappropriate training do not appear to be unloaded during the season and catabolic activities can predominate.
Background Physical exercise is characterized by an increase in oxygen consumption by the whole body. This leads to a decrease in antioxidant levels that could promote both an increase in the markers of lipoprotein peroxidation and damage to the erythrocyte membrane with consequent modification of membrane fluidity.
Materials and methods Different markers of oxidative stress, erythrocyte membrane fluidity and antioxidant status were determined in 20 professional soccer players and 20 sedentary controls. Plasma lipoperoxides and kinetics of Cu-stimulated plasma peroxidation were measured together with hydrosoluble (albumin, uric acid and vitamin C), liposoluble (vitamin E and bilirubin) and enzymatic (superoxide dismutase and glutathione peroxidase) serum antioxidants. Erythrocyte membrane rigidity was determined by measuring fluorescence anisotropy (rs) of the fluorescent probe 1, 3, 5 diphenylexatriene.
Results The sportsmen showed higher levels of the following plasmatic antioxidants: ascorbic acid (P < 0¬?0001), uric acid (P < 0¬?0001), Œ±-tocopherol (P = 0¬?03) and superoxide dismutase activity (P = 0¬?0001). According to this evidence, the lipoperoxide levels (P = 0¬?0158), the duration of the latency phase of plasma peroxidation (P = 0¬?0123) and erythrocytes membrane fluidity (P = 0¬?0152) were found to be significantly higher in the soccer players.
Discussion Athletes undergoing regular and adequate training show improved antioxidant status together with a more fluid membrane status, which could contribute to improving both peripheral resistance to insulin and all the functional metabolic interchanges in the cellular membrane.
The aim of this study was to examine the construct validity of selected field tests as indicators of match-related physical performance. During the competitive season, eighteen professional soccer players (age 26.2 +/- 4.5 yrs, mass 80.8 +/- 7.8 kg, and height 181.9 +/- 3.7 cm) completed an incremental running field test to exhaustion, a vertical-jump and a repeated-sprint ability (RSA) test. Match physical performance was quantified during official matches using a video-computerized, semi-automatic, match analysis image recognition system, (ProZone, Leeds, UK). The selected measures of match physical performance were: total distance covered (TD), high intensity running (HIR: > 14.4 km . h (-1)), very high intensity running (VHIR:> 19.8 km . h (-1)), sprinting (> 25.2 km . h (-1)) and top running speed. Significant correlations were found between peak speed reached during the incremental field test and TD (r = 0.58, R (2) = 0.34; p < 0.05), HIR (r = 0.65, R (2) = 0.42; p < 0.01) and VHIR (r = 0.64, R (2) = 0.41; p < 0.01). Significant correlations were also found between RSA mean time and VHIR (r = - 0.60, R (2) = 0.36; p < 0.01) and sprinting distance (r = - 0.65, R (2) = 0.42; p < 0.01). Significant differences were found between the best and worst group as defined by the median split technique for peak speed (TD = 12 011 +/- 747 m vs. 10 712 +/- 669, HIR = 3192 +/- 482 m vs. 2314 +/- 347 m, and VHIR = 1014 +/- 120 vs. 779 +/- 122 m, respectively; p < 0.05) and RSA mean time (VHIR = 974 +/- 162 m vs. 819 +/- 144 m, and sprinting = 235 +/- 56 vs. 164 +/- 58 m, respectively; p < 0.05). In conclusion, this study gives empirical support to the construct validity of RSA and incremental running tests as measures of match-related physical performance in top-level professional soccer players.
The purpose of this study was to investigate the effect of an imagery training programme on the performance of a soccer task by skilled and novice players. An initial assessment of performance on the soccer task was undertaken, and then 22 skilled and 22 novice players were equally and randomly assigned to either a control or an experimental group. The experimental group was given an imagery training programme consisting of both visual and kinaesthetic imagery, and in which both internal and external imagery perspectives were included. The programme lasted 6 weeks, with the subjects attending bi-weekly sessions of approximately 15 min each. The control group developed a competitive strategy that was totally unrelated to the performance task. Similar to the experimental group, the controls did this over a 6-week period, attending bi-weekly sessions of 15 min duration. Two performance measures were recorded--response time (i.e. the time to complete the soccer task) and performance accuracy (i.e. errors in performing the soccer task recorded in the form of time penalties). Performance on the post-test as measured by response time revealed a significant improvement for both the skilled and novice players in the imagery group. The control group failed to show any such improvement. No effects were found for performance accuracy.
The aims of this study were to examine the release speed of the ball in maximal instep kicking with the preferred
and the non-preferred leg and to relate ball speed to biomechanical di?æerences observed during the kicking
action. Seven skilled soccer players performed maximal speed place kicks with the preferred and the non-
preferred leg; their movements were ®lmed at 400 Hz. The inter-segmental kinematics and kinetics were derived.
A coe??cient of restitution between the foot and the ball was calculated and rate of force development in the hip
¯ exors and the knee extensors was measured using a Kin-Com dynamometer.
Higher ball speeds were achieved with the preferred leg as a result of the higher foot speed and coe??cient of
restitution at the time of impact compared with the non-preferred leg. These higher foot speeds were caused by a
greater amount of work on the shank originating from the angular velocity of the thigh. No di?æerences were
found in muscle moments or rate of force development. We conclude that the di?æerence in maximal ball speed
between the preferred and the non-preferred leg is caused by a better inter-segmental motion pattern and a
transfer of velocity from the foot to the ball when kicking with the preferred leg
The purpose of this study was to evaluate changes in soccerspecific power endurance of 34 female high school soccer players throughout a season either with or without an intermittent, high-intensity exercise protocol. Thirty-four female high school soccer players were tested prior to the 2000 fall season and again 10 weeks later. The tests included an abridged 45-minute shuttle test (LIST), hydrostatic weighing, vertical jump, 20-m running-start sprint, and 30-second Wingate test. The experimental group (EG; n = 17, age 16.5 +/- 0.9 years) completed a 10-week in-season plyometric, resistive training, and high-intensity anaerobic program. The control group (n = 17, age 16.3 +/- 1.4 years) completed only traditional aerobic soccer conditioning. Statistical signifi-cance was set at [alpha] < 0.05. The experimental group showed significant improvements in the LIST (EG = D394 seconds +/- 124 seconds), 20-m sprint (EG = D20.10 seconds +/- 0.10 seconds), increase in fat-free mass (EG = D1.14 kg +/- 1.22 kg), and decreases in fat mass (EG = D21.40 kg +/- 1.47 kg) comparing pre- to postseason. This study indicates that a strength and plyometric program improved power endur-ance and speed over aerobic training only. Soccer-specific power endurance training may improve match performance and decrease fatigue in young female soccer players.
Most physiological profiles of ?©lite soccer players originate from Western Europe and North America. Unfortunately, there is a scarcity of descriptive data on the physical characteristics of Asian soccer players. Therefore, the purpose of this study was to evaluate the physiological profiles of ?©lite soccer players in Hong Kong. It was conducted in conjunction with the selection of the Hong Kong team before the 1990 Beijing Asian Games. In all, 24 professional soccer players were selected from a pool of 180 players as subjects for the study. The following means(s.d.) were observed: height 173.4(4.6) cm; weight 67.7(5.0) kg; body fat 7.3(3.0)%; forced vital capacity (FVC) 5.1(0.6) l; maximum oxygen uptake (VO2max) 59.1(4.9) ml kg-1 min-1; anaerobic threshold (AT 80.0(7.2)% of VO2max; alactic power index 13.5(2.4) W kg-1; lactic work index 298(27) J kg-1; peak isokinetic dominant knee extensor and flexor strengths 2.72(0.36) Nm kg-1 and 1.65(0.20) Nm kg-1. On average the physique of Hong Kong soccer players appeared to be smaller and lighter than those found in Europe, which may be one of the key factors that contribute to the lack of success of Hong Kong soccer teams in international competition.
High femoral bone mineral content and density in male football (soccer) players. Med. Sci. Sports Exerc., Vol. 33, No. 10, 2001, pp. 1682-1687. Purpose: This investigation examined the effect that long-term football (soccer) participation may have on areal bone mineral density (BMD) and bone mineral content (BMC) in male football players. Methods: Dual energy x-ray absorptiometry (DXA) scans were obtained in 33 recreational male football players active in football for the last 12 yr and 19 nonactive subjects from the same population. Both groups had comparable age (23 ¬± 4 yr vs 24 ¬± 3 yr), body mass (73 ¬± 7 kg vs 72 ¬± 11 kg), height (176 ¬± 5 cm vs 176 ¬± 8 cm), and calcium intake (23 ¬± 10 mg¬?kg-1¬?d-1 vs 20 ¬± 11 mg¬?kg-1¬?d-1 (mean ¬± SD). Results: The football players showed 8% greater total lean mass (P < 0.001), 13% greater whole-body BMC (P < 0.001), and 5 units lower percentage body fat (P < 0.001) than control subjects. Lumbar spine (L2-L4) BMC and BMD were 13% and 10% higher, respectively, in the football players than in the control subjects (P < 0.05). Furthermore, football players displayed higher femoral neck BMC (24%, 18%, 23%, and 24% for the femoral neck, intertrochanteric, greater trochanter, and Ward's triangle subregions, respectively, P < 0.05) and BMD (21%, 19%, 21%, and 27%, respectively, P < 0.05) than controls. BMC in the whole leg was 16-17% greater in the football players, mainly because of enhanced BMD (9-10%) but also because of bone hypertrophy, since the area occupied by the osseous pixels was 7% higher (867 ¬± 63 cm2 vs 814 ¬± 26 cm2, P < 0.05). Leg muscle mass was 11% higher in the football players than in the control subjects (20,635 ¬± 2,073 g vs 18,331 ¬± 2,301 g, P < 0.001). No differences were found between the legs in either groups for BMC, BMD, and muscle mass. Left leg muscle mass was correlated with femoral neck BMC and BMD (P < 0.001), as well as with lumbar spine (L2-L4) BMC and BMD (P < 0.001). Conclusion: Long-term football participation, starting at prepubertal age, is associated with markedly increased BMC and BMD at the femoral neck and lumbar spine regions.
Methods Cardiovascular events occurring in patients in the greater Munich area were prospectively assessed by emergency physicians during the World Cup. We compared those events with events that occurred during the control period: May 1 to June 8 and July 10 to July 31, 2006, and May 1 to July 31 in 2003 and 2005.
Results Acute cardiovascular events were assessed in 4279 patients. On days of matches involving the German team, the incidence of cardiac emergencies was 2.66 times that during the control period (95% confidence interval [CI], 2.33 to 3.04; P<0.001); for men, the incidence was 3.26 times that during the control period (95% CI, 2.78 to 3.84; P<0.001), and for women, it was 1.82 times that during the control period (95% CI, 1.44 to 2.31; P<0.001). Among patients with coronary events on days when the German team played, the proportion with known coronary heart disease was 47.0%, as compared with 29.1% of patients with events during the control period. On those days, the highest average incidence of events was observed during the first 2 hours after the beginning of each match. A subanalysis of serious events during that period, as compared with the control period, showed an increase in the incidence of myocardial infarction with ST-segment elevation by a factor of 2.49 (95% CI, 1.47 to 4.23), of myocardial infarction without ST-segment elevation or unstable angina by a factor of 2.61 (95% CI, 2.22 to 3.08), and of cardiac arrhythmia causing major symptoms by a factor of 3.07 (95% CI, 2.32 to 4.06) (P<0.001 for all comparisons).
Conclusions Viewing a stressful soccer match more than doubles the risk of an acute cardiovascular event. In view of this excess risk, particularly in men with known coronary heart disease, preventive measures are urgently needed.
This study measured fluid balance during a 90-min preseason training session in the first team squad (24 players) of an English Premier League football team. Sweat loss was assessed from changes in body mass after correction for ingested fluids and urine passed. Sweat composition was measured by collection from patches attached to the skin at 4 sites. The weather was warm (24-29 degrees C), with moderate humidity (46-64%). The mean +/- SD body mass loss over the training session was 1.10+/- 0.43 kg, equivalent to a level of dehydration of 1.37 +/- 0.54% of the pre-training body mass. Mean fluid intake was 971 +/- 303 ml. Estimated total mean sweat loss was 2033 +/- 413 ml. Mean sweat electrolyte concentrations (mmol/L) were: sodium, 49 +/- 12; potassium, 6.0 +/- 1.3; chloride, 43 +/- 10. Total sweat sodium loss of 99+/- 24 mmol corresponds to a salt (sodium chloride) loss of 5.8 +/- 1.4 g. Mean urine osmolality measured on pre-training samples provided by the players was 666 +/- 311 mosmol/kg (n = 21). These data indicate that sweat losses of water and solute in football players in training can be substantial but vary greatly between players even with the same exercise and environmental conditions. Voluntary fluid intake also shows wide inter-individual variability and is generally insufficient to match fluid losses.
The ability to kick with both feet is regarded as a desirable skill in high level soccer players; however, most players display a dominance of kicking ability on one side. This study investigated the characteristics of asymmetry in two types of soccer kick. A low drive and a chip kick from both the left and right foot of 12 ?©lite junior soccer players were analysed. Kick velocity, kick accuracy, position of the plant foot from the ball centre, and time from foot plant to ball contact were measured for each kick. Knee extension and flexion strength were also determined for each leg at 60 degree s-1, 180 degree s-1 and 240 degrees s-1 on a Cybex II Isokinetic Dynamometer. A single factor repeated measures analysis of variance was applied to velocity, plant foot position and timing parameters to compare between sides and between shots. chi 2 analysis was used to compare accuracy between shots and between sides, and a paired Student's t test was used to compare strength parameters between sides. Pearson's product moment correlation analysis was used to examine the relationship between velocity and both leg strength and the time from foot plant to ball contact. Significance was set at P < or = 0.05. The results showed that this group had strength dominance at all speeds tested on the right side and better drive kick performance with their right leg as determined by mean(s.d.) velocity (79(6) versus 66(8) km h-1) and accuracy (66.6% versus 33.3%). There was no difference in these parameters between sides for chip kicks.(ABSTRACT TRUNCATED AT 250 WORDS)
Sweat rate and sweat composition vary extensively between individuals, and quantification of these losses has a role to play in the individualisation of a hydration strategy to optimise training and competitive performance. Data were collected from 26 male professional football (soccer) players during one 90 min pre-season training session. This was the 2nd training session of the day, carried out between 19.30 and 21.00 h when the mean ¬± SD environment was 32 ¬± 3 ¬?C, 20 ¬± 5 %rh and WBGT 22 ¬± 2 ¬?C. Training consisted of interval running and 6-a-side games during which the average heart rate was 136 ¬± 7 bpm with a maximum rate of 178 ¬± 7 bpm (n = 19). Before and after training all players were weighed nude. During training all players had free access to sports drinks (Gatorade¬Æ) and mineral water (Solan de Cabras¬Æ). All drink bottles were weighed before and after training. Players were instructed to drink only from their own bottles and not to spit out any drink. No player urinated during the training session. Sweat was collected by patches from the chest, arm, back, and thigh of a subgroup of 7 players. These remained in place for the first 15 - 30 min of the training session, and sweat was analysed for sodium (Na+) and potassium (K+) concentration. Body mass loss was 1.23 ¬± 0.50 kg (ranging from 0.50 to 2.55 kg), equivalent to dehydration of 1.59 ¬± 0.61 % of pre-training body mass. The sweat volume lost was 2193 ¬± 365 ml (1672 to 3138 ml), but only 972 ¬± 335 ml (239 to 1724 ml) of fluid was consumed. 45 ¬± 16 % of the sweat volume loss was replaced, but this ranged from 9 % to 73 %. The Na+ concentration of the subgroup's sweat was 30.2 ¬± 18.8 mmol/l (15.5 to 66.3 mmol/l) and Na+ losses averaged 67 ¬± 37 mmol (26 to 129 mmol). The K+ concentration of the sweat was 3.58 ¬± 0.56 mmol/l (2.96 to 4.50 mmol/l) and K+ losses averaged 8 ¬± 2 mmol (5 to 12 mmol). The drinking employed by these players meant that only 23 ¬± 21 % of the sweat Na+ losses were replaced: This ranged from replacing virtually none (when water was the only drink) to replacing 62 % when the sports drink was consumed. These elite soccer players did not drink sufficient volume to replace their sweat loss. This, however, is in accord with data in the literature from other levels of soccer players and athletes in other events. These measurements allow for an individualisation of the club's hydration strategy.
The purpose of this study is to assess if there is any correlation between isokinetic testing and field performance of young soccer players. The isokinetic peak torques of the knee extensor muscles in sitting position (TKE), and those of the hip flexor muscles in standing position (THF) were measured in 24 junior soccer players. Four angular velocities (omega = 1.05, 3.14, 4.19, 5.23 rad.s-1 or 60, 180, 240, 300 deg.s-1) were used for the knee extensors and three (1.05, 3.14, 4.19 rad.s-1) for the hip flexors. On the field the subjects were asked to kick a stationary soccer ball as fast as possible against a barrier and the mean linear velocity over a 10 m path (v) was measured. TKE of the non dominant limb were higher than those of the opposite one at the three highest omega (p < 0.05). On the contrary the THF of the dominant limbs were higher than those of the controlateral, at the two highest omega. When the ball was kicked by the dominant or non dominant limbs, the mean values and standard deviations (+/- SD) of v were 23.6 (+/- 2.5) and 21.4 (+/- 2.6) m.s-1. Torques and v were always positively correlated to each other; however, only in few cases was this relationship statistically significant. In conclusion the isokinetic torques do not seem to be good predictors of v, one of the several factors which determine the global performances of the soccer players.
OBJECTIVE: To examine the dietary habits of professional soccer players at two Scottish Premier League clubs during the competitive season. METHODS: A study of the dietary intake of 51 professional soccer players with two different clubs was carried out by the seven day weighed intake method. RESULTS: Physical characteristics of the two groups of players were similar, with only small differences in age and body mass but no difference in height and body fat. Mean (SD) daily energy intake for club A was 11.0 (2.6) MJ, and for club B 12.8 (2.2) MJ. The higher energy intake at club B was largely accounted for by a higher (P < 0.005) fat intake (118 v 93 g d-1): there was no difference in the absolute amounts of protein, carbohydrate, or alcohol consumed. When expressed as a fraction of total energy intake, mean protein intake was higher (P < 0.05) and fat intake lower (P < 0.01) at club A. CONCLUSIONS: The mean energy intake of these players was not high compared with athletes in endurance sports. Fractional contribution of the macronutrients to total energy intake was broadly similar to that of the general population.
Summary. The aim of this study was to investigate the existence of a relationship between performance capacities and blood levels of testosterone (T) and Cortisol (C). Thirty-two professional soccer players volunteered for the study. Morning levels of hormones were plotted against results of maximal vertical jump with a preparatory counter-movement (CMJ), 30 m running, and Cooper's 12-min running test. The serum T was positively related to both CMJ and average running speed (r= 0.43 and r= 0.47, respectively). Serum levels of C and T were in negative correlation (r= -0.40 and r= -0.49, respectively) with the results of Cooper's test. It was concluded that athletes with better explosive strength and sprint running performances have a higher basal level of testosterone. The results suggest a relationship between testosterone production and development of fast twitch muscle fibres in athletes.
Physiological profiles of elite athletes are becoming increasingly important both for the sport scientist and coach, primarily to effectively develop training programs and to use as a motivational tool in the pursuit of excellence. Descriptive profiles were developed on 16 aspirants of the Canadian Olympic Soccer team during their training program at U.B.C. Selected strength measures were obtained from a Cybex II isokinetic dynamometer at 30 degrees sec-1. Metabolic variables were derived utilizing a Beckman metabolic cart interfaced with a Hewlitt Packard 3052A data acquisition system. Protocols involved were the following: VO2max (initial velocity 8.05 km X h-1, greater than 0.805 km X min-1); Anaerobic speed test (AST) (20% grade, 12.8 km X h-1). the nonlinear increase in excess CO2 was utilized to determine the anaerobic threshold (AT). (Table: see text). Recommendations emphasized maintenance of low body fat, increasing maximal aerobic power by approximately 10% and creating a hams/quads ratio of 60%. Also, a nutritional survey and periodic evaluation of iron status is necessary for the athletes.
Soccer is a game that demands a combination of repeated maximal sprinting wit with 10 to 11km of moderate running, sometimes performed under extremely warm conditions. Over the course of a match, there is partial to near complete depletion of glycogen reserves in the leg muscles (depending on the extent of initial reserves and the level of competition), with a resultant decrease in physical performance. Blood glucose levels also fall, sometimes to values likely to cause a deterioration of both tactical thinking and cooperation between players (3.0 to 3.8 mmol/L), while in tropical climates, fluid losses can amount to 4 to 5kg of bodyweight. The effectiveness of glucose solutions in correcting these problems is limited for 2 main reasons: concentrations greater than 2.5% slow the rate of gastric emptying and thus fluid absorption, while provoking a secretion of insulin with a resultant hypoglycaemia. Fructose solutions are less liable to increase insulin secretion, but they have an equal propensity for slowing gastric emptying; moreover, the ingested fructose is largely metabolised in the liver, without boosting blood glucose. However, glucose polymer preparations have a low osmotic pressure per unit content of glucose equivalent, so that substantial amounts of carbohydrate can be administered in this fashion before gastric emptying is inhibited. If polymers are given before and during a soccer game, they sustain blood glucose, sparing muscle glycogen stores and increasing game performance. If the concentration of polymer is too high, one possible complication is a movement of water from the plasma into the gut; nevertheless, with an appropriate choice of concentration (for example, 7% polycose, 360 mOsm/L, plasma volume is increased rather than decreased relative to that seen with administration of water. Probably because the intergame interval for competitive soccer players is short, replenishment of glycogen reserves proceeds quite slowly. Moreover, this process does not seem to be helped by ingestion of either glucose polymers or a high carbohydrate diet.
The purpose of this study was to investigate the effect of a combined heavy-resistance and running-speed training program performed in the same training session on strength, running velocity (RV), and vertical-jump performance (VJ) of soccer players. Thirty-five individuals were divided into 3 groups. The first group (n = 12, COM group) performed a combined resistance and speed training program at the same training session, and the second one (n = 11, STR group) performed the same resistance training without speed training. The third group was the control group (n = 12, CON group). Three jump tests were used for the evaluation of vertical jump performance: squat jump, countermovement jump, and drop jump. The 30-m dash and 1 repetition maximum (1RM) tests were used for running speed and strength evaluation, respectively. After training, both experimental groups significantly improved their 1RM of all tested exercises. Furthermore, the COM group performed significantly better than the STR and the CON groups in the 30-m dash, squat jump, and countermovement jump. It is concluded that the combined resistance and running-speed program provides better results than the conventional resistance training, regarding the power performance of soccer players.
One-hundred eighty soccer players were tested for muscle strength in knee extension and knee flexion and for flexibility in the lower extremity. The strength measurements were done with a Cybex II isokinetic device (Lumex, Bay Shore, New York). The range of motion (ROM) was measured according to a method described by Ekstrand et al. (1982). The players were divided into groups according to their player position: goalkeepers, defenders, midfielders, and forwards.
The results showed a significantly higher knee extensor torque in goalkeepers and defenders than in forwards (P < 0.05). The knee flexion/knee extension ratio (H/Q ratio) was significantly higher for forwards compared to goalkeepers (P < 0.001) and defenders (P < 0.01). The goalkeepers were significantly more flexible than the other players in hip flexion (P < 0.001), knee flexion (P < 0.01), and ankle dorsiflexion (P < 0.001).
This study examined the effects of ingesting a glucose-polymer (GP) solution on the motor skill proficiencies of association football (soccer) players from two teams playing during two matches in a cool environment. Fifteen minutes before each match and at halftime, players from both teams ingested 5 ml/kg of either placebo or a 6.9% GP solution. GP ingestion did not improve tackling, heading, dribbling, or shooting ability. On the contrary, the mean of successful tackles was lower with GP ingestion than with placebo. The success rate for heading, dribbling, and shooting also tended to be lower in the GP than in the placebo condition. In contrast, success in passing and ball control was similar in the two conditions. Improvements in passing and ball control may have been related to a decrease in the intensity of play in the second half of the game. These data indicate that there are no measurable benefits of GP ingestion for the motor skill proficiencies of soccer players during games played in a cool environment.
Purpose: The purpose of this study was to examine aerobic demands and activity patterns during match play in young soccer players with respect to competition level, age, and biological maturity.
Methods: Ten nonelite players (NbP) and nine elite players (EbP) in their early puberty (12 yr), and seven elite players (EeP) in their late puberty (14 yr) were studied. Heart rate (HR) and activity pattern were recorded during match play, whereas corresponding VÃáO2 and HR values were obtained during submaximal and maximal treadmill tests in the laboratory. The maturity status was assessed from testicular volume.
Results: No difference in VÃáO2max was observed between the nonelite and the elite players in the beginning of puberty (58.7 ¬± 5.3 vs 58.6 ¬± 5.0 mL O2¬?min-1¬?kg-1), whereas the elite players in the end of puberty were significantly more fit (63.7 ¬± 8.5 mL O2¬?min-1¬?kg-1). During match play, a higher HR was recorded in the elite players in the beginning of puberty than their nonelite counterparts, whereas the two elite groups showed the same HR responses (HR 1st half/2nd half-NbP: 162/157; EbP: 177/174; EeP: 178/173). The elite players in the end of puberty thus performed a higher absolute and relative VÃáO2 (VÃáO2¬?min-1 and mL O2¬?min-1¬?kg-1) compared with the nonelite players during both halves, corresponding to more time spent in standing/walking in the nonelite group. The elite players in the end of puberty showed higher absolute VÃáO2 values during match play than the young elite players but identical relative aerobic loads. It seems that the midfield/attack group had the highest absolute VÃáO2max and was performing at the highest HR during the matches.
Conclusion: The present study shows that young soccer players are highly specialized both according to playing level and position on the field.
Several professional soccer schools for talented young players have in recent years been established in Europe. More attention is being paid to the development of young talented players in the soccer clubs, and the physical training and the tactical organization in the field seems to be implemented much earlier. Methods for analysis during match play have been developed and include heart rate (HR) measurements, and observational studies of motion analysis and running pattern (3,9,23). Activity registration has become easier and inexpensive by the use of small microcomputers in field studies (19). The activity patterns and physiological demands have therefore been well-reported in adult soccer players with regard to competition level and position on the field during competition matches (1-4,16,19,24).
However, in spite of the increasing focus on the optimization of physical and tactical skills in talented young soccer players, surprisingly few studies have been published regarding the physiological demand and the activity pattern of young soccer players (6,8,13). Moreover, these studies fail to couple the observed activity pattern and the aerobic load during match play. Klimt et al. (14) measured the HR during competition and noncompetition games in 11- to 12-yr-old boys but did not relate these measurements to the level of competition.
The purpose of the present study was to record the aerobic energy demand during match play and relate it to maturity status and competition level (elite vs nonelite) of young soccer players. Furthermore, the activity pattern and the influence of specialization due to playing position on the field were examined.
A comparison of the under-18 (U-18) and under-16 (U-16) squads of the Canadian national soccer team with a representative sample of Canadians (Canada Fitness Survey, 1983) showed a tendency for the development or selection of the older players in teams of stature (U-18, 175.8 cm; U-16, 171.1 cm; CFS, 170.9 cm) and lean body mass (U-18, 63.4; U-16, 57.9; CFS, 54.2 kg). The larger lean mass of the older players could not be explained simply by size. The U-18s also showed greater isokinetic leg extension force (particularly for rapid movements) and explosive strength (vertical jump) relative to the younger players, although the knee extension force was less than in some classes of athlete. Part of the gain in mass seems due to local training of the hip and leg muscles and part to a more general muscular development. Contrary to some reports, the hip flexibility of the Canadian players (sit and reach test) was greater than for a national sample; this may be important in avoiding soft tissue injuries to the legs. However, aerobic power (58.3 +/- 5.3 ml kg-1 min-1) and body fat (8.0 +/- 1.1%) were unremarkable.
Men and women from a southern university's intercollegiate varsity soccer teams gave saliva samples before and after league matches. For the men, samples were collected for a single game ending in victory. For the women, samples were collected for two games, one of which ended in victory and the other in defeat. For both men and women, match competition substantially increased saliva cortisol (C) and testosterone (T). For women, play-related increases in saliva C and T were similar in victory and defeat. For both men and women, saliva T (but not C) was highly correlated with teammate ratings of playing abilities–one measure of status with teammates–and self-ratings of social connectedness with teammates, but the nature of the relationship was different according to sex. For men, play-related changes in T were positively correlated with these variables, but before-game T was not. For women, before-game T was positively related to each of these variables, but play-related changes in T were not. Status and social connectedness are pertinent to understanding interpersonal dynamics in most social groups, and these results–which link T and these variables in an athletic context–may have relevance for understanding social relationships in other settings.
Strategies for a nutrition education as applied to individual soccer players provide a key to guiding them towards appropriate food selection. Scientific investigations have associated energy requirements, composition of the diet and carbohydrate intake with muscle glycogen storage, and adequacy of fluids with optimal athletic performance. In general, soccer players appear to consume adequate energy but low carbohydrate diets. The training diet should be comprised of 55-65% carbohydrate, 12-15% protein and less than 30% fat. The goal of the training diet is to provide adequate energy for weight maintenance, and 7-10 g of carbohydrate per kg body weight for maximizing glycogen storage. Nutritional needs for competition include eating prior to and after matches. Consumption of carbohydrate-rich foods for energy needs and glycogen resynthesis are key behaviours soccer players need to focus on daily. Qualified dietitians should be on hand to provide personal nutrition counselling, carbohydrate resource lists and education on food labels as simple and quick nutrition education strategies to guide soccer players, their parents, coaches and trainers towards improved food selections.
Primary objective: To analyse serum concentrations of two biochemical markers of brain tissue damage, S-100B and NSE (neurone-specific enolase), in male soccer players in connection to the game.
Methods: Blood samples were taken in players before and after a competitive game and the numbers of headers and of trauma events during soccer play were assessed.
Results: Both S-100B and NSE were significantly raised in serum samples obtained after the game in comparison with the pre-game values (S-100B: 0.118±0.040µgL−1 vs 0.066±0.025µgL−1, p<0.001; NSE: 10.29±2.16µgL−1 vs 8.57±2.31µgL−1, p<0.001). Only changes in S-100B concentrations (post-game minus pre-game values) were statistically significantly correlated to the number of headers (r=0.428, p=0.02) and to the number of other trauma events (r=0.453, p=0.02).
Conclusion: Playing competitive elite soccer was found to cause increase in serum concentrations of S-100B and NSE. Increases in S-100B were significantly correlated to the number of headers, and heading may accordingly have contributed to these increases.
The physiological response to the physical exercise involves a number of changes in the oxidative balance and in the metabolism of some important biological molecules, including nitric oxide (NO) and heat shock proteins (Hsp 70). With the aim to optimise previous laboratory diagnostic panels, we measured the plasma concentration of reactive oxygen metabolites (ROMs), total antioxidant status (TAS), glutathione reductase (GR) activity, and NO and Hsp 70 levels in 44 elite, antioxidant-supplemented and trained soccer players and in 15 sedentary controls. Although no statistically significant difference between athletes and controls was detected in the plasma level of ROMs and TAS, soccer players showed a significantly higher plasma GR activity, NO and Hst 70 levels than those of sedentary controls. These findings suggest that the measuring of relatively novel biomarkers in sport medicine, like GR, NO and Hsp 70, in addition to the well-known and reliable assays (d-ROMs test and TAS) may be useful to a clinician to better assess and evaluate the benefits of training and/or supplementation programs.
This study determined the fiber type composition, the fiber size, and the capillary characteristics of the vastus lateralis muscle in 11 young, elite, male soccer players and 8 sedentary male, age-matched controls. There were no significant differences (P less than 0.05) in the fiber type percentages and fiber diameter between the soccer players and controls; however, all fiber types tended to be larger in the soccer players. The soccer players possessed a greater capillary supply; this was characterized by a significantly greater mean number of capillaries surrounding each fiber (5.7 +/- 0.9 vs. 4.9 +/- 0.4), a significantly larger capillary density (282.7 +/- 42.0 vs. 220.8 +/- 38.1), and a significantly higher capillary to fiber ratio (2.2 +/- 0.6 vs 1.7 +/- 0.1). The results indicate that soccer may be an appropriate stimulus for simultaneous adaptation to endurance and high intensity exercise.
Purpose: To examine the physiological response, reliability, and validity of the Yo-Yo intermittent recovery level 2 test (Yo-Yo IR2).
Methods: Thirteen normally trained male subjects carried out four Yo-Yo IR2 tests, an incremental treadmill test (ITT), and various sprint tests. Muscle biopsies and blood samples were obtained, and heart rate was measured before, during, and after the Yo-Yo IR2 test. Additionally, 119 Scandinavian elite soccer players carried out the Yo-Yo IR2 test on two to four occasions.
Results: Yo-Yo IR2 performance was 591 ¬± 43 (320-920) m or 4.3 (2.6-7.9) min. Test-retest coefficient of variation in distance covered was 9.6% (N = 29). Heart rate (HR) at exhaustion was 191 ¬± 3 bpm, or 98 ¬± 1% HRmax. Muscle lactate was 41.7 ¬± 5.4 and 68.5 ¬± 7.6 mmol¬?kg-1 d.w. at 85 and 100% of exhaustion time, respectively, with corresponding muscle CP values of 40.4 ¬± 5.2 and 29.4 ¬± 4.7 mmol¬?kg-1 d.w. Peak blood lactate was 13.6 ¬± 0.5 mM. Yo-Yo IR2 performance was correlated to ITT performance (r = 0.74, P < 0.05) and VÀôO2max (r = 0.56, P < 0.05) but not to 30- and 50-m sprint performance. Yo-Yo IR2 performance was better (P < 0.05) for international elite soccer players than for moderate elite players (1059 ¬± 35 vs 771 ¬± 26 m) and better (P < 0.05) for central defenders (N = 21), fullbacks (N = 20), and midfielders (N = 48) than for goalkeepers (N = 6) and attackers (N = 24). Fifteen elite soccer players improved (P < 0.05) Yo-Yo IR2 performance by 42 ¬± 8% during 8 wk of preseasonal training.
Conclusion: This study demonstrates that the Yo-Yo IR2 test is reproducible and can be used to evaluate an athlete's ability to perform intense intermittent exercise with a high rate of aerobic and anaerobic energy turnover. Specifically, the Yo-Yo IR2 test was shown to be a sensitive tool to differentiate between intermittent exercise performance of soccer players in different seasonal periods and at different competitive levels and playing positions.
The effects of in-season, high-intensity interval training on professional male soccer players' running performances were investigated. Twenty-two subjects participated in 2 consecutive training periods of 10 weeks. The first period was considered a control period and was compared with a period where 2 high-intensity interval training exercises were included in the usual training program. Intermittent runs consisted of 12-15 runs lasting 15 seconds at 120% of maximal aerobic speed alternated with 15 seconds of rest. Sprint repetitions consisted of 12-15 all-out 40-m runs alternated with 30 seconds of rest. Results from the high-intensity interval training have shown that maximal aerobic speed was improved (18.1 +/- 3.1%; p < 0.001) and that the time of the 40-m sprint was decreased (23.5 +/- 1.5%; p < 0.001), whereas no change in either parameters were observed during the control period. This study shows that improvements in physical qualities can be made during the in-season period.
Six male football players competed in a 90 min game (4-a-side) on two occasions following an exercise and diet (either high- -65% or low- -30% carbohydrate intake) regimen designed to manipulate muscle glycogen concentrations. Movement and technical parameters of performance and selected physiological responses were measured. Pre-game muscle glycogen concentrations following the high carbohydrate diet (mean ± SD) (395.6±78.3 mmol.kg-1 dw) were significantly higher than following the low carbohydrate diet (287.1±85.4 mmol kg-1 dw). The results of the movement analysis showed that the players performed significantly more (∼33%) high intensity exercise in the game played following the high carbohydrate diet. No significant differences were found, between the two dietary conditions, in any of the measured technical variables. Plasma FFA and glycerol concentrations in the game played following the low carbohydrate diet were significantly higher after 45 min (905±103 and 293±23 μmol.l-1) and post exercise (1388±122 and 366±36 μmol.l-1) compared to the game played following the high carbohydrate diet (532±137 and 202±55 μmol.l-1 and 888±192 and 266±27 μmol.l-1, respectively). Post-exercise blood glucose levels were significantly lower in the game played following the low carbohydrate diet (5.8±0.3 vs 7.2±0.3 mmol.l-1). No significant differences were found in the mean blood lactate values (3.5±0.6 and 3.9±0.5 mmol.l-1) or mean heart rates (162 vs. 163.5 beats. min-1) between the high and low carbohydrate conditions, respectively. The main finding from this study was that the carbohydrate content of the diet influenced the amount of high intensity exercise performed during a small-sided football game. This suggests that to optimise performances, in not only football but possibly also other multiple sprint sports of similar duration, a high carbohydrate diet should be administered in preparation for intense training and competition.
Forty-eight players from four senior, male soccer teams were tested for ranges of motion (ROM) in the lower extremity before, immediately after, and 24 h after different forms of soccer training.
The players were tested after regular soccer training (A), after soccer training wih contract-relax stretching prior to beginning the session (B), and after soccer training with stretching added at the end of the program (C). Each training session lasted 1.5 h.
In group A all six ROMs were decreased 24 h after the training. In group B the only change in ROM noted was an increase in knee flexion directly after the training. In group C there was an increase in hip extension, hip flexion, and knee flexion directly after the training.
Purpose: To characterize in-shoe pressure measurements during different soccer-specific maneuvers on two playing surfaces to identify the main loading areas of the foot.
Methods: Twenty-one experienced male soccer players participated in the study (25.5 ± 1.8 years, 78.7 ± 5.4 kg, and 182.9 ± 5.7 cm). The Pedar Mobile system was used to collect plantar pressure information inside the soccer shoe. Four soccer-specific movements were performed (normal run, cutting maneuver, sprint, and goal shot) on both a grass and a red cinder surface.
Results: Results showed characteristic pressure distribution patterns with specific loading areas of the foot that correspond to the evaluated movements. In addition, loading patterns with higher pressure values than those observed during normal run were found. In cutting, the medial part of the foot; in sprinting, the first and second ray; and in kicking, the lateral part of the foot are predominantly loaded. No global effect of the two surfaces on pressure parameters was found.
Conclusion: The results of the present investigation suggest that the high load in soccer in combination with a high repetition may have an important influence in the development of overuse injuries.
This study examined the relation between field-test results and match performance in elite Italian soccer referees. Subjects (n = 22) were all experienced elite-level referees enrolled in the Commissione Arbitri Nazionali (CAN) and thus officiating in the Serie A and B Italian championships. Referees were, on separate occasions, tested for fitness (50-m, 200-m, and 12-minute run tests) and observed a minimum of 1 and a maximum of 3 times (n = 39) during Serie A matches. Match analyses were performed considering 11 match activity categories. Analyses of correlations were performed considering 50-m, 200-m, and 12-minute run test performances as independent variables and total distance, maximal speed distance (runs performed at speeds faster than 24 km[middle dot]h-1), and high-intensity activity distance (runs performed at speeds faster than 18 km[middle dot]h-1, high intensity activity [HIA]) as dependent variables. Statistical significance was set at p <= 0.05. In the 50-m, 200-m, and 12-minute run tests the referees scored, 7.07 +/- 0.26 seconds, 29.57 +/- 1.44 seconds, and 2866 +/- 164 m, respectively. The 12-minute run test showed a moderate correlation with total match distance (r = 0.71, p < 0.05), and a low correlation with HIA and maximal speed distance (r = 0.51, p < 0.05 and r = 0.32, p < 0.05, respectively). The 200-m and 50-m sprint times were not correlated with the distance covered at maximal speed or HIA, but correlated negatively with match distance (r = -0.48, p < 0.05 and r = -0.38, p < 0.05, respectively). The results of the present study demonstrate that the 12-minute run test is a moderate predictor of match performance in elite referees and that aerobic fitness should have priority in the physical conditioning programs of the elite soccer referee.
The effect of adding cognitively demanding elements to the performance of a real-world motor task in which functional interference existed among the elements in performance was investigated across level of expertise. The primary task involved running as quickly as possible through a slalom course. Two secondary tasks were used: running through the slalom while dribbling a soccer ball and identification of geometric shapes projected on a screen at the end of the slalom course. Four novice, 5 intermediate, and 5 expert female soccer players performed 3 trials each of the 3 experimental conditions. Although the addition of cognitively demanding elements caused a decrement in performance, the amount of decrement decreased as level of expertise increased. (PsycINFO Database Record (c) 2009 APA, all rights reserved)
Conducted 2 experiments to verify that the conceptions presented by professional soccer players or varsity soccer players are dependent on their ego vs task involvement conditions (Exp 1) or their motivational ego vs task orientations (Exp 2). Since a strong interaction was obtained between motivational goals and competence feedback on related effort assumptions, the study predictions received empirical support. Furthermore, because previous research in academic settings also indicated that individual differences in goal orientations are positively related to the kind of information strategies used, a 2nd set of predictions concerned the determinants of learning strategies in sport context (i.e., soccer shooting). Results confirmed previous findings showing that, in comparison to ego-orientated Ss, task-oriented Ss use more deep-processing strategies irrespective of the kind of feedback provided. (French, Spanish, German & Italian abstracts) (PsycINFO Database Record (c) 2009 APA, all rights reserved)
We compared the efficacy of three physical conditioning programmes provided over a 12 week period (24 h in total) on selected anthropometric and physical fitness parameters in female soccer players. Two of the groups received physical conditioning training in accordance with speed, agility and quickness (SAQ); one group used specialized resistance and speed development SAQ equipment (equipment group; n = 12), while the other group used traditional soccer coaching equipment (non-equipment group; n = 12). A third group received their regular fitness sessions (active control group; n = 12). All three interventions decreased (P < 0.001) the participants' body mass index (-3.7%) and fat percentage (-1.7%), and increased their flexibility (+14.7%) and maximal aerobic capacity (VO2max) (+18.4%). The participants in the equipment and non-equipment conditioning groups showed significantly (P < 0.005) greater benefits from their training programme than those in the active control group by performing significantly better on the sprint to fatigue (-11.6% for both the equipment and non-equipment groups versus -6.2% for the active control group), 25 m sprint (-4.4% vs -0.7%), left (-4.5% vs -1.0%) and right (-4.0% vs -1.4%) side agility, and vertical (+18.5% vs +4.8%) and horizontal (+7.7% vs +1.6%) power tests. Some of these differences in improvements in physical fitness between the equipment and non-equipment conditioning groups on the one hand and the active control group on the other hand were probably due to the specificity of the training programmes. It was concluded that SAQ training principles appear to be effective in the physical conditioning of female soccer players. Moreover, these principles can be implemented during whole team training sessions without the need for specialized SAQ equipment. Finally, more research is required to establish the relationship between physical fitness and soccer performance as well as the principles underlying the improvements seen through the implementation of SAQ training programmes.
Of all the skills required to participate in soccer, none has received more attention from a biomechanical perspective than kicking. When skilled behavior, such as kicking, is evaluated there are two successive stages. Initially, movements are organized and simplified through powerful, temporal coupling between joint complexes so that the neuromuscular system becomes functionally useful for the learner. In the second stage, the learner's behavior becomes more efficient and organized as the active muscular and joint forces become more economical. [10]
Individual patterns of positive-negative affect (PNA) were studied in 25 Olympic level soccer players (age 17-21). Recall idiographic scaling following the methodology of the individual Zones of Optimal Functioning (IZOF) model was used to identify PNA items related to each player's effective and ineffective game performance. Individual zones for each item were then estimated on the Borg's Category Ratio (CR-10) scale. Optimal and non-optimal PNA patterns were revealed in the selection of idiosyncratic items, their intensity ranges and functions. All PNA items were functionally either facilitating (23.1%), debilitating (42.3%), or both (34.6%). Significant differences in PNA content and intensity (zones) were revealed only at intra- and inter-individual but not at the group level. Pre-game negative ineffective affect in successful players anticipated two days before the important tournament deviated more from non-optimal zones than in less successful players. The data support the findings obtained in ice-hockey and extend Hanin's IZOF model to performance PNA in soccer. Implications for idiographic assessments and application of the IZOF model in team sports are suggested.
In a randomized, placebo-controlled study the effect of 10 weeks of supplementation with either 5.2 g of a concentrated fish oil triglyceride (Triomar™) enriched in omega-3 fatty acids (1.60 g/day EPA and 1.04 g/day DHA) or 5.2 g corn oil (serving as placebo) on maximal aerobic power, anaerobic threshold and running performance was assessed in 28 well-trained male soccer players (18–35 years). Supplements were given as 650-mg capsules. Capsule assignment was randomized to one omega-3 group (n=15), given eight Triomar™ capsules per day, and one placebo group (n=13), given eight capsules of corn oil per day. During the 10-week supplementation period the subjects maintained their usual diets and training regimes. Red blood cell (RBC) osmotic fragility, triglycerides and fatty acid composition in plasma were assessed before and after the supplementation period. The pre- and post-supplementation tests of maximal aerobic power, anaerobic power and running performance showed no significant difference between the two groups. Subjects in the omega-3 group had significantly reduced plasma triglycerides, rised EPA (175%) and DHA (40%) in the total lipid fraction of plasma after supplementation. RBC osmotic fragility did not change. In conclusion, the results do not support the hypothesis that endurance athletes can improve maximal aerobic performance by omega 3-fatty acid supplementation.
Objective: To prospectively document the incidence of competition-related injury rates in an international youth soccer tournament and to analyze the type and location of injuries by age and gender.
Design: A prospective injury report form completed for injured players presenting to a medical facility for evaluation by the medical staff.
Setting: An international youth soccer tournament occurring annually during mid-July.
Participants: 89,500 soccer players, ages 9-19.
Measurement/Main Results: A total of 3840 new, play-related injuries were evaluated during 290,344 player-hours of competition from 1988 through 1997. New, play-related injuries per 1000-player-hours decreased from 19.87 in 1988 to 9.89 in 1997. Female injury rates ranged from a maximum of 20.11 in 1989 to a minimum of 10.23 in 1996 and the male injury rate ranged from a maximum of 20.04 in 1988 to a minimum of 7.60 in 1996. The lowest injury rate occurred in the under-19 females (10.64) and highest rates occurred in under-16 (17.68) and under-15 (16.92) females. Heat illness correlated with mean temperature. The aggregate rate of heat illness was 0.6 cases/1000 player-hours under normal conditions compared to a rate of 2.8/1000 player-hours during hot years.
Conclusions: Injury rates for both genders declined over the 10-yr span of the USA Cup study. The aggregate rate of injury was slightly higher for females than males although the difference between male and female rates became less significant as the tournament matured. In conditions of extreme heat and humidity (1988 and 1995) the rate of new, heat illness increased compared with normal years and females were 1.6 times more likely to sustain heat illness than males.
19-Norandrosterone (19-NA) and 19-noretiocholanolone (19-NE) are the two main indicators used to prove the illegal use of nandrolone by humans. Recent studies showed that 19-NA and 19-NE can be endogenously produced in some individuals. The mediated cases observed over the last three years generated some questions about the appropriateness of the official International Olympic Committee cutoff level, which is 2 ng/mL of 19-NA in male urine samples. In the present study, professional soccer players belonging to the French First League were studied over a period of 19 months. In total, 385 urine samples were taken immediately before and after soccer competitions and were coupled with 200 blood samples for testosterone and LH determination. Results of the study showed that the mean values for 19-NA and 19-NE were 0.097 ng/mL and 0.033 ng/mL, respectively. For 19-NA, 70% of the samples proved to be below 0.1 ng/mL, whereas less than 20% were found to be between 0.1 and 0.2 ng/mL, and 7% were between 0.2 and 0.3 ng/mL. Only four urine samples were above 1.0 ng/mL; the maximal value was 1.79 ng/mL. For 19-NE, only one sample was above 1.0 ng/mL; the value was 1.42 ng/mL. Concentrations of these compounds after games were generally significantly higher than those before games.
The aim of this study was to examine the effect of a soccer
(strength and technique) training program on kinematics
and electromyographic (EMG) muscle activity during a
instep kick. Ten amateur soccer players (aged 19.9 ?Ü 0.4
years, body mass 74.8 ?Ü 9.1kg, height 177.4 ?Ü 6.7 cm)
constituted the experimental group (EG) whereas 10 players
(age 21.6 ?Ü 1.3 years, weight 71.5 ?Ü 6.7 kg, height
175.2 ?Ü 3.4 cm) served as controls (CG). The EG followed
a 10-week soccer-specific training program combining
strength and technique exercises. All participants performed
an instep soccer kick using a two-step approach while three-
dimensional data and EMG from six muscles of swinging
and support legs were recorded prior to and after training.
Maximum isometric leg press strength, 10-m sprint perfor-
mance and maximum speed performance on a bicycle
ergometer were also measured. Analysis of variance designs
with repeated measures showed that the EG improved
significantly (Po0.05) maximum ball speed, the linear
velocity of the foot, ankle and angular velocity of all joints
during the final phase of the kick. Training had insignificant
effects on EMG values, apart from an increase in the
averaged EMG of the vastus medialis whereas maximum
isometric strength and sprint times significantly improved
after training (Po0.05). The present results suggest that the
application of the training programs using soccer-specific
strength exercises would be particularly effective in improv-
ing of soccer kick performanc
Observations were made every 4 h on 2 teams during 91 h 45 min of 5-a-side soccer to investigate stresses on players. Variables monitored were subjective fatigue, state anxiety, grip strength, heart rate, activity, urine protein concentration and liquid intake. Circadian functions were identified in all variables except protein urine as well as significant intercorrelations. Periodicities were consistent with arousal theory with troughs at about 0500-0600 h and crests at 1800 h to 2100 h. Group mean anxiety values increased between days as play was prolonged whilst significant decrements were found in activity, exercise heart rate and urine protein. Mean heart rate for the duration of play was 98 (± S.D. = 10) beats min-1 and the work severity was considered light. Behavioural abnormalities as found by other investigators in chronically sleep deprived subjects were common during the final two nights.
A battery of 26 tests was administered to professional soccer players (n = 31) at 3 points during the competitive season. Significant changes from start to mid-season were limited to improved muscular power, increased resting heart rate (fH), decreased force expiratory flow (FEF) and ankle mobility. No further changes with the duration of the competitive season were observed. Differences between squads were predominantly cardiac function measures at mid-season, and strength, muscular power and limb girths at the end of the season. The First Team squad had consistently less fat and poorer ankle mobility. It seems that mean fitness levels remain relatively stable during the playing season, though the measures significantly discriminating between the top and reserve squads fluctuate.
Eighteen elite Greek soccer players (age, 27.8 +/- 3.4 years; height, 176.6 +/- 5.2 cm; weight, 75.5 +/- 5.2 kg) were tested on the Cybex(R) II apparatus in order to determine 1) the maximal muscle power for the lower extremity dominant side at angular velocities of 30 degrees /sec, 90 degrees /sec, and 180 degrees /sec; 2) the total muscular output and the relative power at 30 degrees /sec; 3) the relationship between the muscle power of the agonist and antagonist musculature. The absolute maximal muscle power (Nm) at 30 degrees /sec for the different joint movements was as follows: Hip Ext = 269 +/- 39; Hip Flex = 179 +/- 29; Hip Add = 160 +/- 17; Hip Abd = 119 +/- 24; Knee Ext = 247 +/- 29; Knee Flex = 146 +/- 12; PI. Flex = 120 +/- 22; and Do. Flex = 32 +/- 6. The muscle agonist-antagonist percent relationship at 30 degrees /sec was found to be: (hip flex)/(hip ext) = 66%(hip abd)/(hip add) = 74%(knee flex)/(knee ext) = 60%(dor. fle)/(pl. fle) = 28%These findings have significant implications for preseason conditioning programs as well as for minimizing the rate of muscle injuries by restoring the correct relationship between agonist-antagonist musculature.J Orthop Sports Phys Ther 1985;6(5):293-295.
To determine the daily energy requirements of professional soccer players during a competitive season, we measured total energy expenditure in seven players (age 22.1 ¬± 1.9 years, height 1.75 ¬± 0.05 m, mass 69.8 ¬± 4.7 kg; mean ¬±s) using the doubly labelled water method. Energy intake was simultaneously estimated from 7 day self-report dietary records. Mean total energy expenditure and energy intake were 14.8 ¬± 1.7 MJ ¬? day-1 (3532 ¬± 408 kcal¬? day-1) and 13.0 ¬± 2.4 MJ ¬? day-1 (3113 ¬± 581 kcal¬? day-1), respectively. Although there was a significant difference between total energy expenditure and energy intake (P < 0.01), there was a strong relationship between the two (r = 0.893, P < 0.01). Basal metabolic rate and recommended energy allowance calculated from the Recommended Dietary Allowances for the Japanese were 7.0 ¬± 0.3 MJ ¬?day-1 (1683 ¬± 81 kcal¬? day-1) and 15.6 ¬± 0.8 MJ ¬? day-1 (3739 ¬± 180 kcal¬? day-1), respectively. A physical activity level (total energy expenditure/ basal metabolic rate) of 2.11 ¬± 0.30 indicated that, during the competitive season, professional soccer players undertake much routine physical activity, similar to that of competitive athletes during moderate training. Energy intake estimated using dietary records was under-reported, suggesting that its calculation from these data does not predict energy expenditure in soccer players.
Recent evidence suggests that certain soccer drills produce exercise intensities suitable for physical conditioning. However, it remains debatable whether soccer drills can provide a sufficiently unified exercise intensity among different players and on repetition of a drill, because movement patterns cannot be externally controlled during soccer drills. Good reliability and low variability of exercise intensity would enable all players to receive an appropriate training stimulus. The purpose of this study was to investigate intersubject variability and intrasubject reliability in exercise intensity during soccer drills. It was hypothesized that soccer drills that involve the highest exercise intensities would demonstrate the lowest intersubject variability and the highest intrasubject reliability. Heart rates of 23 professional soccer players were recorded during a range of soccer training drills. The drills consisted of 2 vs. 2 to 8 vs. 8 normal scoring games and 2 further possession games. Heart rate responses were examined for variability, reliability, and suitability for soccer endurance training. Coefficients of variation across players were less than 3% for all drills. Paired t-tests showed no significant differences in heart rate on repetition of the drills and 95% ratio limits of agreement were 1.8-3.8%. There were no significant correlations between exercise intensity and the statistical measures of variability and reliability. Several drills produced exercise intensities suitable for soccer endurance training with mean heart rate responses ranging from 87-91% HRmax. Soccer drills such as those used in the present study appear to be an adequate substitute for physical training without the ball and thus provide simultaneous skill and fitness training. The increase in training time spent developing technical ability and/or a reduction in total training time required may be useful for soccer teams.
In order to validate the use of heart rate (HR) in describing and monitoring physiological demands during soccer activities, the HR versus oxygen uptake (VdotO2) relationship determined on the field during soccer-specific exercises was compared to that found in the laboratory during treadmill exercise. Seven male amateur soccer players [mean (SE), age 25.3 (1.2) years, body mass 72.9 (2.1) kg, stature 1.76 (0.03) m] performed three trials on the field (two laps of a purpose-made circuit including a variety of soccer activities) at different intensities (moderate, high and very high, according to their rate of perceived exertion) and an incremental test on a treadmill in the laboratory. HR increased linearly with VdotO2 during both field and laboratory tests according to exercise intensity (P<0.01). The mean correlation coefficients of the HR–VdotO2 relationships obtained in the laboratory and on the field were 0.984 (0.012) and 0.991 (0.005) (P<0.001), respectively. The mean value of the HR–VdotO2 regression equation slope and intercept obtained in laboratory [0.030 (0.002) and 79.6 (4.6), respectively] were not significantly different compared to those found on the field [0.032 (0.003) and 76.7 (9.7)]. The present study seems to confirm that HR measured during soccer exercises effectively reflects the metabolic expenditure of this activity. Thus, with the aid of laboratory reference tests, the physiological demands of soccer activities can be correctly estimated from HR measured on the field in amateur soccer players.
Aim. Dominance of one leg may cause asymmetry between the contralateral muscle groups and develop predisposition for injury to the leg with the weaker muscle strength. The purpose of this study was to examine the strength balance in the extensor and flexor muscle groups, as well as the hamstring to quadriceps (H/Q) ratios of both legs in professional soccer players with dominance on one or both legs. Methods. Forty-two professional soccer players of the first Greek division participated in this study. Participants were divided into 3 groups according to their leg use during training sessions and matches. Fifteen players comprised the first group with dominance to the right leg, 12 players formed the second group with dominance to the left leg, and 15 players consisted the third group with dominance to both the right and left legs. Maximum voluntary concentric torque of the hamstring and quadriceps muscles of both legs was assessed using a Norm isokinetic dynamometer at angular velocities of 12¬?, 60¬?, 180¬? and 300¬?/s. Results. No significant differences in the strength balance found between the groups. The isokinetic variables comparing the right and left body side in each group, with dominance on one or both legs, did not differ. No differences were recorded in the H/Q between the right and left legs for any of the subject groups. Conclusion. There is no evidence of muscle imbalances in extensor and flexor muscle groups and H/Q ratios between the right and left legs in professional soccer players with dominance on one or both legs. The training sessions and matches appear to have imposed strength balance for the right and left body sides of professional soccer players.
Objective: To examine the influence of in-season injury prevention training on hip and knee kinematics during a landing task.
Design: Longitudinal pre-post intervention study.
Setting: Testing sessions were conducted in a biomechanics research laboratory.
Participants: Eighteen female soccer players between the ages of 14 and 17 participated in this study. All subjects were healthy with no current complaints of lower extremity injury.
Interventions: Testing sessions were conducted prior to and following a season of soccer practice combined with injury prevention training.
Main Outcome Measurements: During each testing session three-dimensional kinematics were collected while each subject performed a drop landing task. Peak hip and knee joint angles were measured during the early deceleration phase of landing and compared between pre- and post-training using paired t-tests.
Results: Following a season of soccer practice combined with injury prevention training, females demonstrated significantly less hip internal rotation (7.1¬? vs. 1.9¬?; P=0.01) and significantly greater hip abduction (-4.9¬? vs. -7.7¬?; P=0.02). No differences in knee valgus or knee flexion angles were found post-season.
Conclusions: Female soccer players exhibited significant changes in hip kinematics during a landing task following in-season injury prevention training. Our results support the premise that a season of soccer practice combined with injury prevention training is effective in altering lower extremity motions that may play a role in predisposing females to ACL injury.
Soccer requires field players to exercise repetitively at high intensities for the duration of game, which can result in marked muscle glycogen depletion and hypoglycemia. A soccer match places heavy demands on endogenous muscle and liver glycogen stores and fluid reserves, which must be rapidly replenished when players complete several matches within a brief period of time. Low concentrations of muscle glycogen have been reported in soccer players before a game, and daily carbohydrate (CHO) intakes are often insufficient to replenish muscle glycogen stores. CHO supplementation during soccer matches has been found to result in muscle glycogen sparing (39%), greater second-half running distances, and more goals being scored with less conceded, when compared to consumption of water. Thus, CHO supplementation has been recommended prior to, during, and after matches. In contrast, there is currently insufficient evidence to recommend without reservation the addition of electrolytes to a beverage for ingestion by players during a game resulting in sweat losses of < 4% of body weight.
Background: Technological limitations associated with oesophageal and rectal temperature probes have previously limited match play observations of body temperature.
Objective: To investigate the application of an intestinal pill system to measure core temperature during dynamic, field based, soccer matches.
Methods: Core temperature (Tc) was assessed using the intestinal pill system (CorTemp 2000) and changes in plasma volume were calculated using the values for haemoglobin and packed cell volume obtained before and after recreational (n‚Ää=‚Ää8) and the professional soccer (n‚Ää=‚Ää7) matches.
Results: In the recreational match, there were significant post-match reductions in body mass (‚àí1.6%, p<0.05) and plasma volume (‚àí7.2%, p<0.01). Significant increases were observed in Tc from rest to half time (p<0.01) and from half time to full time (p<0.05). In the professional match, body mass decreased by 1.9% (p<0.05) and plasma volume by 11.6% (p<0.01). Tc increased from rest to half time (p<0.01) but was unchanged from half time to full time. Significant associations were observed between maximum oxygen consumption and match play heart rates in the second half of each match but these were not related to changes in plasma volume or Tc.
Conclusions: Intestinal temperature proved a useful method of recording core temperature during soccer match play and assisted in the measurement of alterations in thermoregulatory variables in response to both professional and recreational level soccer matches; however, technological limitations still restrict the wider application of this method, especially at a competitive level.
Most football players and coaches agree that players are capable of learning to use both feet with equal frequency
and e??ciency ą that is, become `two-footed’. There is also some consensus that two-footed play is associated
with skill in individual players. If these assumptions are true, then the world’s elite football players should be
substantially less `one-footed’ than the rest of the population. To examine this issue, we quanti??ed the pattern of
foot use in a sample of 236 players from 16 teams in the 1998 World Cup (France ’ 98). Our ??ndings indicate that
World Cup players are as right-footed as the general population (~79%). The remaining players were largely left-
footed and as biased towards the use of their preferred foot as their right-footed counterparts. Very few players
used each foot with equal frequency. Remarkably, both left- and right-footed players were as skilled, on average,
with their non-preferred foot as they were with their preferred foot, on the rare occasions when they used it.
Therefore, it is unlikely that infrequent use of one foot compared to the other foot can be accounted for by skill
di?£erences between the feet. Players were most asymmetrical for set pieces; nevertheless, ??rst touches, passes,
dribbles and tackles were rarely performed with the non-preferred foot as well. Our results support a biological
model of foot preference and performance, as well as demonstrating the usefulness of soccer for studies of lateral
asymmetries
Sports provide a natural experiment on individual choices in games with high stakes.
We study soccer with a gameMtheoretic model of a match, and then evaluate the ability
of this model to explain actual behavior with data from 2885 matches among professional
teams. In our model, the strategy of a team depends on the current state of the game.
When the game is tied, both teams attack. A losing team always attacks, while its winning
opponent attacks early in the game, but it starts defending as the end of the match nears.
We find that teamsG skills, current score, and home field advantage are significant exM
planatory variables of the probability of scoring. We also find that a team which falls
behind is relatively more likely to score. A team which is ahead, on the other hand, uses a
conservative strategy very early in the match.
These results support the main conclusions of our model. They indicate that soccer
teams behave consistently with rationality and equilibrium. However, there is significant
evidence that emotional factors are roughly as important as rational ones in determining
the gameGs outcome, and they affect the strategic decisions of teams.
Regarding the influence of the left ventricular (LV) adaptation by sports-specific factors the supposed endurance training have so far been compared mainly to strength conditioning. In the present study we investigated the echocardiographic LV measurements of endurance-trained athletes in different kinds of endurance sports (running and ball games) by using matched-pair procedures. We examined 22 male soccer players (S) and 22 male 400-m runners (R) on a regional up to a national level with--each similar in pairs--the following body mass (S: 75.7 +/-5.0 kg; R: 75.2 +/- 5.6), body surface area (S: 1.97 +/- 0.09 m2; R: 1.98 +/- 0.09), fat-free body mass (S: 68.4 +/- 4.6 kg; R: 68.3 +/- 5.3) and individual anaerobic threshold as a criterion to determine the running endurance (S: 14.23 +/- 0.79 km.h-1; R: 14.25 +/- 0.80). The body dimensions-related heart volume (HV/lean body mass: S: 14.2 +/- 1.5 ml.kg-1; R: 13.4 +/- 1.0) as well as the absolute and body surface-related LV internal diameter (EDD: S: 55.0 +/- 3.8 mm; R: 52.7 +/- 3.3; EDD/body-surface area: S: 27.8 +/- 1.9 mm.m-2; R: 26.6 +/- 1.3) were measured significantly higher in S as compared to R (p < 0.05 and p < 0.01, respectively). In both groups, free LV wall thickness, enddiastolic diameter and LV muscle mass correlated significantly with the body dimensions (fat-free body mass: r = 0.42 - 0.48 - 0.56; p < 0.004, respectively). In conclusion, specific sport-related strain like frequent exercises in interval form (typical for ball games) and a different volume/intensity ratio could significantly influence the LV adaptation beside the endurance performance as well as constitutional and genetic factors.
A three-compartment body composition analysis of 42 professional football (soccer) players and 33 age- and body mass index–matched control subjects was determined by dual X-ray absorptiometry (DXA). The equipment provided a direct measurement of fat, lean, and bone mass. Fat mass was significantly higher in the controls subjects whereas lean mass and bone mass were markedly higher in the players. The percentage of body weight fat varied from 6.1 to 19.5% in the football players and from 9.1 to 29.9% in the control subjects. The respective averages were 12.0 ± 3.1 and 19.2 ± 5.6% (p < 0.001). The midfielders had a significantly higher percentage of fat (13.6 ± 3.3%) than backs or forwards (11.1 ± 2.8 and 11.0 ± 2.3%, p < 0.05 and p < 0.06, respectively). In the football players, the correlation between age and fat mass was significant (r = 0.53, p < 0.001), whereas there was no correlation between fat and age in the control subjects (r = 0.13, p > 0.1). This article provides, for the first time, DXA analysis of body composition of football players in relation to their age and function. The results should be of interest to coaches because they will help improve athletes' performance.
Background: As soccer participation in the United States increases, so does the number of children at risk for injury.
Purpose: To examine pediatric soccer-related injuries presenting to US emergency departments from 1990 to 2003.
Study Design: Descriptive epidemiology study.
Methods: A descriptive analysis of nationally representative, pediatric, soccer-related injury data from the US Consumer Product Safety Commission’s National Electronic Injury Surveillance System.
Results: Among those 2 to 18 years of age, a nationally estimated 1597528 soccer-related injuries presented to US emergency departments from 1990 to 2003. Mean age was 13.2 years (range, 2–18 years); 58.6% were male. From 1990 to 2003, there was an increase in the absolute number of injuries among girls (P < .0001). The wrist/finger/hand (20.3%), ankle (18.2%), and knee (11.4%) were the most commonly injured body parts. The most common diagnoses were sprain/strain (35.9%), contusion/abrasion (24.1%), and fracture (23.2%). Boys were more likely to have face and head/neck injuries (17.7%; relative risk, 1.40; 95% confidence interval, 1.32–1.49; P < .01) and lacerations/punctures (7.5%; relative risk, 3.31; 95% confidence interval, 2.93–3.74; P < .01) than were girls (12.7% and 2.3%, respectively). Girls were more likely to have ankle injuries (21.8%; relative risk, 1.38; 95% confidence interval, 1.33–1.45; P < .01) and knee injuries (12.9%; relative risk, 1.25; 95% confidence interval, 1.15–1.35; P < .01) than were boys (15.7% and 10.4%, respectively). Girls were more likely to have sprains or strains (42.4%) than were boys (31.3%; relative risk, 1.36; 95% confidence interval, 1.31–1.40; P < .01). Children 2 to 4 years old sustained a higher proportion of face and head/neck injuries (41.0%) than did older children (15.5%; relative risk, 2.65; 95% confidence interval, 2.09–3.36; P < .01).
Conclusion: When comparing these data to available national statistics that estimate participation in youth soccer, true injury rates may actually be decreasing for boys and girls. Young children should be closely supervised because of risk of head injuries and rate of hospitalization. The establishment of a national database of soccer participation and injury data is needed to better identify injury risks.
Yoyo tests are very popular in soccer; however, no study has addressed details of their relation to canonical aspects of aerobic fitness. Furthermore, no information is available on the effect of the individual levels of lower limbs' explosive strength on yo-yo tests in soccer players. The purpose of this study was to examine the physiological determinants of Yo-yo Endurance Test Level 2 (YYETL2) and Yo-yo Intermittent Recovery Test Level 1 (YYIRTL1) in soccer players. Twenty-four soccer players (body mass, 74.6 +/- 8.5 kg; height, 178.1 +/- 4.5 cm; age, 25.6 +/- 5.1 years) were tested for [latin capital V with dot above]O2max and ventilatory threshold (VT) on a motorized treadmill. Lower-limb explosive strength was assessed using vertical countermovement jumps (CMJ) performed on a force platform. Results showed that YYETL2 and YYIRTL1 performances (m) were significantly related (r = 0.75, p = 0.00002). YYETL2 results were significantly related to [latin capital V with dot above]O2max, [latin capital V with dot above]O2, and speed at VT (r = 0.75, 0.76, and 0.83, respectively; p < 0.00002). Peak treadmill speed results were significantly related to YYETL2 and YYIRTL1 (r = 0.87 and 0.71, respectively; p < 0.0003). YYIRTL1 was related to CMJ peak power (r = 0.57; p = 0.003). These findings show that YYETL2 and YYIRTL1, although adopting similar starting and progression speeds, are influenced by different physiological variables. From these results, YYETL2 can be considered an aerobic fitness-related field test, whereas YYIRTL1 can be regarded as an aerobic-anaerobic, soccer-specific field test.
The purpose of the study was to develop a method to record intramuscular electromyogram (EMG) from the iliopsoas muscle and to relate this activity to the kinetics during the soccer place kick. Seven skilled soccer players performed 3 maximal velocity place kicks. The kicks were filmed with a high-speed camera (400 Hz) and EMG recordings were obtained from 5 muscles of the kicking leg, including wire electrodes inserted into the m. iliopsoas. The EMG signals were compared to the kinetics of the kicking leg, which were calculated from the digitised film. The results showed hardly any torque reversal about the hip joint before impact. Angular deceleration of the thigh segment did not increase the angular velocity of the shank (work -3.57 to 0.0%). M. iliopsoas was active during the entire kicking motion (average EMG 65.1–100.9%), even in the period when the thigh was decelerating. Wire electrodes can succesfully be applied to EMG recordings of fast unloaded movements.
Aim: Changes in leucocyte and monocyte subpopulations were investigated in 10 elite male soccer players aged 16–19 years. The purpose was to perform a descriptive study of immunological alterations in elite soccer players in response to two consecutive games separated by 20 h. It was hypothesized that in response to two games the players would show signs of short-term immunosuppression.
Methods: Blood samples were taken before the first soccer game, immediately after the second game and after 6, 24, 48 and 72 h. Cell surface antigens, testosterone and cortisol were investigated.
Results: During the first 6 h after the second game there was a significant increase in number of circulating neutrophils, mature (CD20+ CD5+) B cells and CD4/CD8 ratio. A significant decrease was observed in the number of natural killer (NK) cells, monocytes and adhesion on lymphocytes and monocytes. In a delayed phase, 48 h after the second game the expression of both adhesion and signalling molecules increased on lymphocytes and monocytes. Changes in adhesion and signalling molecules at 48 h correlated negatively to the subjects VO2max, suggesting larger immunological response to similar exercise in subjects with lower aerobic exercise capacity.
Conclusion: In response to competitive soccer exercise some immunological variables are enhanced while others are depressed. Observed changes may serve a purpose in adaptation to exercise by signalling via adhesion.
Visual Reaction Time (RT) was measured by presenting three different sizes of stimulus to the central and peripheral fields of vision in 6 soccer players and 6 nonathletes. An electromyogram was recorded from the flexor digitorum superficialis muscle of the responding forearm. Peripheral visual RT was longer in comparison to central visual RT due to an increment in Premotor Time. The soccer players showed shorter Premotor Times during central and peripheral visual RT tasks than nonathletes, suggesting that the soccer players are better able to respond quickly to a stimulus presented to peripheral as well as central positions.
Purpose: To investigate the effect on gastric emptying of intermittent exercise at varying intensities such as occurs during a soccer match.
Methods: We compared the emptying rate of a carbohydrate-electrolyte (CE) drink during two 15-min periods of a competitive 5-a-side indoor soccer match separated by 10 min and during two 15-min periods of low-intensity walking exercise. Seven healthy male subjects, all of whom regularly played soccer, completed the study. Exercise intensity on each trial was calculated from heart rate recordings. Subjects ingested 500 mL of the CE drink immediately before starting each exercise period. Before and after completing each 15-min exercise period, the gastric contents were aspirated and the volume recorded. Ambient room temperature ranged from 16-22¬?C and humidity ranged from 57-72% on both trials.
Results: Mean ± SD heart rate was higher during the Soccer trial than during the Walking trial at all time points. Exercise intensity was calculated to be 54 ± 23% and 63 ± 20% V̇O2max, respectively, for the first and second periods of exercise on the Soccer trial and 13 ± 9% and 12 ± 11% V̇O2max, respectively, for the first and second periods of exercise on the Walking trial. During the first 15-min period of exercise, a greater (median (range)) volume of the CE drink was emptied from the stomach on the Walking trial (247 mL (102-361 mL)) than on the Soccer trial (84 mL (17-230 mL);P = 0.022). In the second exercise period, however, gastric emptying rates were not different (P = 0.16) between the Walking trial (247 mL (104-363 mL)) and Soccer trial (148 mL (17-293 mL)).
Conclusion: As indicated by heart rate, the overall exercise intensity of an indoor soccer match appears to be moderate. The pattern of activity during a match is intermittent with periods of low level activity punctuated by short bursts of high-intensity sprinting. The present study demonstrates that the intensity of activity during this type of exercise is sufficient to slow gastric emptying.
The purpose of this investigation was to determine if a 9-wk youth soccer program had any effect on cardiorespiratory fitness (VO2maxand VO2submax), peak knee torque, and flexibility. Subjects were 20 sixth grade boys, 11 of whom were members pf a YMCA soccer team; 9 were normally active boys who were not participating in any organized sport during the study who served'as a control group. Mean ages (+/-SD) were 11.8 +/- 0.34 and I; 1.5 +/- 0.60 yr for the soccer and control group, respectively. Initial VO2max values of 49.83 and 47.42 ml.kg-1-min-1 for the soccer and the control group, respectively, are similar to those reported in the literature for untrained normal boys of this age. Results indicated that playing soccer three times weekly increased VEmax and reduced VO2 (ml.kg-1.min-1 and|.min-1) at a submaximal running speed (all P's<0.O5), while no change in VO2max was noted. No significant training effect was observed in peak knee torque or flexibility subsequent to soccer training. It is concluded that the effects of playing soccer in these subjects resulted in no change in cardiprespiratory fitness, peak knee torque, or flexibility.
Purpose: The purpose of this research project was to noninvasively determine individual muscle glycogen [Gly] degradation during a test intended to predict individual fatigue in intense soccer matches.
Methods: The [Gly] of the calf muscles of 17 elite soccer players [age = 17.4 ± 0.8 (SD)] were measured with 13C-MRS before and after an alternating velocity test to exhaustion. Blood samples were taken before and 3 min after the test for determination of blood metabolites.
Results: Average muscle [Gly] was 135 ¬± 53 mmol¬?(kg wet weight)-1 before and 87 ¬± 27 mmol¬?(kg wet weight)-1 (P < 0.001) after exhaustion (42 ¬± 25 min). There was a high correlation (r = 0.87, P < 0.0001) between muscle [Gly] at rest and net muscle [Gly] utilized. There was also a more moderate correlation (r = 0.62, P < 0.01) between net muscle [Gly] used and time to exhaustion during the soccer-specific test. There was some evidence of correlation (r = 0.42, P = 0.09) between resting [Gly] and time to exhaustion. Plasma lactate increased (P < 0.001) from 0.8 ¬± 0.4 before the test to 2.5 ¬± 1.0 mmol¬?L-1 at exhaustion, whereas ammonia was raised (P < 0.0001) from 44.1 ¬± 10.3 to 89.7 ¬± 14.9 Œºmol¬?L-1. Similarly, plasma free fatty acids were elevated (P < 0.0001) from 148 ¬± 106 to 797 ¬± 401 Œºmol¬?L-1, and glycerol was increased (P < 0.0001) from 48.3 ¬± 17.7 to 182.2 ¬± 61.8 Œºmol¬?L-1. Insulin levels (11.9 ¬± 3.7 vs 11.7 ¬± 4.8 ŒºU¬?mL-1) remained the same. Creatine kinase levels increased (P < 0.0001) from 486 ¬± 501 to 640 ¬± 548 Œºmol¬?L-1 after the test.
Conclusions: We conclude that exhaustion during soccer-specific performance is related to the capacity to utilize muscle [Gly]. The results underline the importance of dietary counseling (glycogen loading and resynthesis strategies) and proper training to enhance the glycogen levels and glycogenolytic capacity of the players.
Numerous variables influence soccer kick performance and among those initial soccer ball velocity is considered to be important. The purpose of this study was to investigate the correlation between initial ball velocity and two physical characteristics: relative isokinetic torque of the lower extremity and muscle contraction velocity. Eleven elite Greek soccer players age 25.5 plus or minus 3 years, weight 73.6 plus or minus 5.6 kg, height 176.5 plus or minus 5.5 cm, were tested on an isokinetic apparatus at different angular velocities to determine isokinetic muscle torque of the dominant lower extremity. To determine muscle contraction velocity and initial soccer ball velocity a cycling ergometer and a photocell apparatus were used, respectively.
Using a Cybex II(R) dynamometer, the quadriceps and hamstring torque levels of 16 female high school soccer players were measured. Both the dominant and nondominant knees were tested at a fast (1 80 per second) and slow (30 per second) speed. The results were similar to those of previous studies that used men as subjects. The conclusions were: 1) Extension torque is significantly greater than flexion torque for both legs and at both speeds. At 30 per second the hamstring1 quadriceps ratio is 0.6 1. This ratio increases to 0.78 at 180 per second. 2) There is no significant difference between dominant and nondominant legs for either flexion or extension torque at fast or slow speed. 3) At 30' per second, peak quadriceps torque is achieved at approximately 73 of extension, and peak flexion torque is achieved at approximately 38 flexion. 4) Slow speed flexion and extension torque levels are significantly greater than fast speed torque levels for both legs.
The objective of this study was to analyze the validity of the velocity corresponding to the onset of blood lactate accumulation (OBLA) and critical velocity (CV) to determine the maximal lactate steady state (MLSS) in soccer players. Twelve male soccer players (21.5 +/- 1.0 years) performed an incremental treadmill test for the determination of OBLA. The velocity corresponding to OBLA (3.5 mM of blood lactate) was determined through linear interpolation. The subjects returned to the laboratory on 7 occasions for the determination of MLSS and CV. The MLSS was determined from 5 treadmill runs of up to 30-minute duration and defined as the highest velocity at which blood lactate did not increase by more than 1 mM between minutes 10 and 30 of the constant velocity runs. The CV was determined by 2 maximal running efforts of 1,500 and 3,000 m performed on a 400-m running track. The CV was calculated as the slope of the linear regression of distance run versus time. Analysis of variance revealed no significant differences between OBLA (13.6 +/- 1.4 km[middle dot]h-1) and MLSS (13.1 +/- 1.2 km[middle dot]h-1) and between OBLA and CV (14.4 +/- 1.1 km[middle dot]h-1). The CV was significantly higher than the MLSS. There was a significant correlation between MLSS and OBLA (r = 0.80), MLSS and CV (r = 0.90), and OBLA and CV (r = 0.80). We can conclude that the OBLA can be utilized in soccer players to estimate the MLSS. In this group of athletes, however, CV does not represent a sustainable steady-state exercise intensity.
Abstract. The preferential use of dominant over non-dominant limbs produces muscle hypertrophy in the dominant limb. The purpose of this study was to investigate the architectural characteristics of the muscle that are associated with dominant leg use in junior soccer players. Fascicle length, pennation angle and muscle thickness of the medial gastrocnemius (MG) were measured by B-mode ultrasound in 26 junior soccer players [mean (SD) age: 16.5 (0.6) years] and 20 control college students [age: 18.5 (0.5) years]. Lower leg circumference and MG muscle thickness were significantly (P<0.05) greater in the soccer players than in the controls. The percent difference (dominant minus non-dominant legs) in muscle thickness and fascicle length were significantly (P<0.01) larger in the soccer players than in the controls, but the percent difference in pennation angle was similar between groups. The difference (dominant leg minus non-dominant leg) in muscle thickness was significantly correlated (r=0.55; P<0.05) with the difference in muscle fascicle length in the soccer players, but not in the controls (r=0.18). In conclusion, the preferential use of one limb over another, as seen in junior soccer players, results in a greater difference in muscle thickness between the dominant and non-dominant legs. This difference in muscle size was associated with longer fascicle lengths of the dominant leg. Thus, it appears possible that fascicle length may be further influenced by physical training in dominant legs.
Early research into how goals were scored in association football (Reep and Benjamin, 1968) may have shaped the tactics of British football. Most coaches have been affected, to a greater or lesser extent, by the tactics referred to as the “long-ball game” or “direct play”, which was a tactic employed as a consequence of this research. Data from these studies, published in the late 1960s, have been reconfirmed by analyses of different FIFA World Cup tournaments by several different research groups. In the present study, the number of passes that led to goals scored in two FIFA World Cup finals were analysed. The results conform to that of previous research, but when these data were normalized with respect to the frequency of the respective lengths of passing sequences, there were more goals scored from longer passing sequences than from shorter passing sequences. Teams produced significantly more shots per possession for these longer passing sequences, but the strike ratio of goals from shots is better for “direct play” than for “possession play”. Finally, an analysis of the shooting data for successful and unsuccessful teams for different lengths of passing sequences in the 1990 FIFA World Cup finals indicated that, for successful teams, longer passing sequences produced more goals per possession than shorter passing sequences. For unsuccessful teams, neither tactic had a clear advantage. It was further concluded that the original work of Reep and Benjamin (1968), although a key landmark in football analysis, led only to a partial understanding of the phenomenon that was investigated.
The aim of this study was to examine the effects of a carbohydrate-electrolyte drink on specific soccer tests
and performance. Twenty-two professional male soccer players volunteered to participate in the study. The
players were allocated to two assigned trials ingesting carbohydrate-electrolyte drink (7% carbohydrates,
sodium 24 mmol.l-1, chloride 12 mmol.l-1, potassium 3 mmol.l-1) or placebo during a 90 min on-field soccer
match. The trials were matched for subjects’ age, weight, height and maximal oxygen uptake. Immediately
after the match, players completed four soccer-specific skill tests. Blood glucose concentration (mean±SD)
was higher at the end of the match-play in the carbohydrate-electrolyte trial than in the placebo trial (4.4±0.3
vs. 4.0±0.3 mmol.l-1, P < 0.05). Subjects in the carbohydrate-electrolyte trial finished the specific dribble test
faster in comparison with subjects in the placebo trial (12.9±0.4 vs. 13.6±0.5 s, P < 0.05). Ratings of the
precision test were higher in the carbohydrate-electrolyte trial as compared to the placebo trial (17.2±4.8 vs.
15.1±5.2, P < 0.05) but there were no differences in coordination test and power test results between trials.
The main finding of the present study indicates that supplementation with carbohydrate-electrolyte solution
improved soccer-specific skill performance and recovery after an on-field soccer match compared with
ingestion of placebo. This suggests that soccer players should consume carbohydrate-electrolyte fluid
throughout a game to help prevent deterioration in specific skill performance.
Deformation analysis using 2-dimensional strain echocardiography can detect early systolic function abnormalities in patients with left ventricular hypertrophy. This study was designed to characterize global and regional myocardial deformation using 2-dimensional strain in professional soccer players (PSPs) compared with control subjects and patients with hypertrophic cardiomyopathy (HC). Twenty nine PSPs, 26 patients with HC, and 17 controls were investigated at rest using transthoracic echocardiography with 2-dimensional strain analysis. Radial and transverse strains were significantly higher in PSPs compared with controls, whereas longitudinal strain was lower. Compared with patients with HC, athletes had higher values for transverse, radial, and circumferential strains. In pathologic hypertrophic segments, longitudinal strain was lower in patients with HC than in PSPs. In conclusion, 2-dimensional strain can identify specific patterns of myocardial deformation in PSPs, controls, and patients with HC. It has the potential to become a routinely used method for the differentiation of athlete’s heart and HC.
The authors studied the frequency distribution of α-actinin-3 (ACTN3) R577X genotypes in 60 top-level professional soccer players. The results were compared with those of 52 elite endurance athletes and 123 sedentary controls. The per cent distribution of RR and RX genotypes in soccer players (48.3% and 36.7%) was significantly higher and lower, respectively, than controls (28.5% and 53.7%) and endurance athletes (26.5% and 52%) (p = 0.041). Although there are notable exceptions, elite soccer players tend to have the sprint/power ACTN3 genotype.
Background: It is a matter of debate whether or not ordinary heading of the ball in soccer causes injury to brain tissue.
Objective: To analyse concentrations of the biochemical markers of brain tissue damage S-100B and neurone specific enolase (NSE) in serum of female elite soccer players in association with a competitive game.
Methods: Venous blood samples were obtained from 44 female soccer players before and after a competitive game for analysis. The number of headers and trauma events (falls, collisions, etc) was assessed from videotape recordings for each player.
Results: Concentrations of both brain damage markers were increased after the game (S-100B, 0.18 (0.11) v 0.11 (0.05) μg/l (p  =  0.000); NSE, 10.14 (1.74) v 9.05 (1.59) μg/l (p  =  0.001)). There was a significant correlation between changes in S-100B concentrations and both the number of headers (r  =  0.430, p  =  0.004) and the number of other trauma events (r  =  0.517, p<0.001).
Conclusion: The concentrations of both S-100B and NSE were increased by game associated activities and events. The increases in S-100B concentration were significantly related to the number of headers and other trauma events, which indicates that both these factors may have contributed to these increases.
Soccer involves high-intensity, intermittent exercise and places a heavy demand on the body's liver and muscle glycogen reserves. Thus, carbohydrate depletion may contribute, in part, to fatigue and reduced performance during a soccer match. In addition, fatty acids derived from both adipose tissue and intramuscular triglyceride stores will be utilized. Soccer players engaged in strenuous competition and training should be encouraged to consume a diet that is relatively high in carbohydrate (at least 55% of total energy intake). Furthermore, the inclusion of carbohydrate in beverages consumed during and after a soccer match is likely to enhance performance and facilitate the recovery of liver and muscle glycogen reserves.
Abstract. Recommendations for the requirements for protein intake amount usually to 0.8‚Äì1.0 g¬?kg‚Äì1 body mass¬?day‚Äì1 in adolescents without any reference to the undertaking of acute exercise or to the training status. The present investigation intended to determine the nitrogen balance and protein intake in 8 healthy male non-active adolescents and 11 adolescent soccer players, both groups aged about 15 years. An assessment of nutrient intake was obtained by analysing 7 day food records collected by a questionnaire. Nitrogen excretion rate was determined and nitrogen balance was calculated from the mean daily protein intake and the urinary excretion. The results showed that the nutritional status of the two groups was similar. Nevertheless, we found that their diets were quite inappropriate in terms of the intakes of carbohydrate, some minerals (zinc, calcium, magnesium), vitamins (A, B6, D) and fibre. A positive nitrogen balance was observed from a mean protein intake of 1.57 g¬?kg‚Äì1 body mass¬?day‚Äì1 in these adolescents, whether they were non-active or athletes. Thus, the present investigation indicated that the growth and development in non-active adolescents and in adolescent soccer-players give rise to a need for a higher protein intake than is usually recommended. However, the higher protein requirements did not seem to be related only to the increased energy expenditure imposed by the exercise training in the soccer-player group.
The aim of this experiment was to evaluate bilateral motor performance effects from training the non-dominant leg of competitive soccer players. The subjects were 39 soccer players, 15–20 years of age, performance-matched and randomly divided into a training group (n = 18) and a control group (n = 21) both belonging to the same team. Both groups were tested by using two standardised foot-tapping tests and three soccer-specific tests. The training intervention consisted of the experimental group participating in all parts of their soccer training except full play, using the non-dominant leg for 8 weeks. Statistical analyses for the soccer-specific tests revealed that the experimental group improved significantly as compared to the control group from the pre-test to the post-test period in their use of the trained non-dominant leg. Somewhat unexpectedly, the experimental group also improved significantly in the tests, which made use of the dominant side. The standardised foot-tapping tests revealed similar results. The results might be explained by improved generalised motor programmes, or from a Dynamic Systems Approach, indicating that the actual training relates to the handling of all the information available to the subject in the situation, and that the body self-organises the motor performance.
In this article, we investigate the pay-performance relationship of soccer players using individual data from eight seasons of the German soccer league Bundesliga. We find a nonlinear pay-performance relationship, indicating that salary does indeed affect individual performance. The results further show that player performance is affected not only by absolute income level but also by relative income position. An additional analysis of the performance impact of team effects provides evidence of a direct impact of team-mate attributes on individual player performance.
The purpose of this study was to capture the lower limb kinematics before during and after ball impact of soccer kicking by examining the influence of both sampling rate and smoothing procedures. Nine male soccer players performed maximal instep kicks and the three-dimensional leg movements were captured at 1000 Hz. Angular and linear velocities and accelerations were determined using four different processing approaches: processed using a modified version of a time-frequency filtering algorithm (WGN), smoothed by a second-order low-pass Butterworth filter at 200 Hz cut-off (BWF), re-sampled at 250 Hz without smoothing (RSR) and re-sampled at 250 Hz but filtered by the same Butterworth filter at 10 Hz cut-off (RSF). The WGN approach appeared to establish representative kinematics, whereas the other procedures failed to remove noisy oscillation from the baseline of signal (BWF), lost the peaks of rapid changes (RSR) or produced totally distorted movement patterns (RSF). The results indicate that the procedures used by some previous studies may have been insufficient to adequately capture the lower limb motion near ball impact. We propose a new time-frequency filtering technique as a better way to smooth data whose frequency content varies dramatically.
Objective: To examine the changes in aerobic endurance performance of professional youth soccer players throughout the soccer season.
Methods: Nine youth soccer players were tested at six different time points throughout the soccer season by sub-maximal blood lactate assessment, using an incremental treadmill protocol. Whole blood lactate concentration and heart frequency (Hf) were determined at each exercise stage. Running velocities at the first lactate inflection point (v-Tlac) and at a blood lactate concentration of 4 mmol l‚àí1 (v-4mM) were determined.
Results: Running velocity at the two lactate thresholds increased from the start of pre-season training to the early weeks of the competitive season, from 11.67 (0.29) to 12.96 (0.28) km h‚àí1 for v-Tlac, and from 13.62 (0.25) to 14.67 (0.24) km h‚àí1 for v-4mM (p<0.001). However, v-Tlac and v-4mM when expressed relative to maximum heart frequency (Hfmax) remained unchanged. The Hf to blood lactate concentration relationship was unchanged after the pre-season training period. The two expressions of lactate threshold did not reveal differences between each other.
Conclusion: Running velocity at v-Tlac and v-4mM increased significantly over the pre-season period, but v-Tlac and v-4mM were unchanged when expressed relative to Hfmax. This finding may indicate that increased endurance performance may be mainly attributable to alterations in Vo2max. Although lactate assessment of soccer players is useful for determining endurance training adaptations in soccer players, additional assessment of the other two determinants of endurance performance (Vo2max and running economy) may provide more useful information for determining physiological adaptations resulting from soccer training and training interventions.
Young, French male athletes undergoing intensive elite sports training at the National Training Centre in Clairefontaine served as the subjects (N = 180; age range: 13 to 16 years) in a 3-year dietary survey aimed at characterizing their nutritional intake in terms of energy, macronutrients, calcium, and iron. Each year, the subjects were grouped by level into 3 promotions so that 9 groups could be studied. Dietary intake data were collected each year for each subject in the 9 groups, using a 5-day food record. The results showed that their total energy intake (TEI) was insufficient for athletes (ranging from 2352 454 to 3395 396 kcal/d as opposed to the recommended range of between 3819 and 5185 kcal/d). Furthermore, their diet was unbalanced, with too great an emphasis upon fatty foods (29.1 2.8 to 34.1 3.1% TEI vs. the 20% recommended), to the detriment of carbohydrates (48.5 4.3 to 56.6 3.1% TEI vs. the 55 to 60% recommended). The calcium intake was too low in 5 of the 9 groups while, in contrast, the iron intake was satisfactory in all groups. Furthermore, during this 3-year period at the Clairefontaine Centre, the subjects significantly (p <.05) improved their calcium and iron intakes (1021 197 and 12 2 mg/d in 1996, 1299 155 and 16 2 mg/d in 1997, and 1252 184 and 17 2 mg/d in 1998). This rise in micronutrient intakes may have been due to a physiological adaptation to growth or to the positive effects of courses on nutrition given during their stay at the Centre.
The aim of this study was to examine the variability in physiological and perceptual responses and time–motion profiles of various small-sided soccer game (SSG) formats (2 versus 2, 4 versus 4 and 6 versus 6 players) and regimes (interval and continuous). Typical error (TE) was calculated for mean heart rate as a percentage of maximum heart rate (%HRmax), global ratings of perceived exertion (RPE), blood lactate [La−] and various time–motion characteristics for 16 male soccer players (mean 16.2 years, range 15.6–17.9). The TE for HR responses were <5% for all SSGs. RPE also demonstrated small variability across all SSGs, with TE ranging between 1 and 2 units. In contrast, the TE% for [La−] was higher, ranging from 16% (2 versus 2-interval) to 34% (4 versus 4-interval). The TE% for total distance (TD) and distance covered at 0–6.9km/h was <5% for all SSGs, with 2 versus 2 interval and continuous games recording the lowest TE (2.2% and 2.9%, respectively). An increase in game format size does not appear to influence the variability of the acute physiological responses to SSGs, although continuous formats display less variability than interval formats. The TD, distance covered and percentage of total time moving at 0–6.9km/h demonstrated small variability across all formats and regimes. However, higher movement speeds zones (>8km/h) reflected increased variability, irrespective of game format or regime. Collectively, these results suggest that SSG training can provide a reliable aerobic training stimulus.
| , high-intensity running [HIR] and very high-intensity running [VHIR]) and other measures including involvement with the ball and peak running speed were collected. The influence of opponent team, the level of opposition, first half physical activities on second half activities, and playing position were analysed. The main finding was that TD (r = 0.62, p < 0.05), HIR (r = 0.51, p < 0.05), and VHIR (r = 0.65, p < 0.05) of the reference team was influenced by the activity profile of the opponent teams. The TD and HIR was higher against Best opponent teams compared to Worst opponent teams (p < 0.05), and the TD, HIR and VHIR travelled in the first half significantly influenced the distances covered in the second half. TD, HIR and VHIR were greater at the end of the season. These results may be used to interpret meaningful changes in match performance in top level soccer. The Use and Abuse of Painkillers in International Soccer Data From 6 FIFA Tournaments for Female and Youth Players 1. Philippe Tscholl, MD‚Ć*, 2. Nina Feddermann, MD‚Ä°, 3. Astrid Junge, PhD‚Ƃİ and 4. Jiri Dvorak, MD‚Ƃİ,¬ß + Author Affiliations 1. ‚Ć FIFA Medical Assessment and Research Center (F-MARC), the 2. ‚Ä° Schulthess Klinik, and the 3. ¬ß F?©d?©ration Internationale de Football Association (FIFA), Zurich, Switzerland 1. *Address correspondence to Philippe Tscholl, FIFA Medical Assessment and Research Center, Lengghalde 2, 8008 Zurich, Switzerland (e-mail: Philippe.Tscholl@access.unizh.ch). Abstract Background It is known that in professional men‚Äôs soccer the consumption of prescription medication is high. Purpose The intake of medication in female and adolescent male soccer players has not yet been investigated. Study Design Descriptive epidemiology study. Material Team physicians reported 10 456 uses of medication 72 hours before each match in 2488 soccer players participating in 6 international soccer tournaments. Results The use of a total of 6577 medical substances was reported, leading to an average intake of 0.63 substances per player per match (under-17s, 0.51; under-20s, 0.51; women, 1.0; P ‚⧠.001 [without contraceptive medication, 0.85; P < .001]). Nonsteroidal anti-inflammatory drugs were the most commonly prescribed type of medication in all tournaments. Women‚Äôs soccer had the highest percentage of players using nonsteroidal anti-inflammatory drugs per match (under-17s, 17.3%; under-20s, 21.4%; women, 30.7%; P ‚⧠.001). Relatively few players were taking Œ?2-agonists for the treatment of asthma (under-17s, 1.3%; under-20s, 1.3%; women, 4.3%; P ‚⧠.001). Conclusion These findings highlight the existing problem of excessive medication use in international top-level women‚Äôs and male youth soccer nearly to the same extent as in men‚Äôs soccer. Further steps need to be taken to understand the rationale underlying the sports physicians‚Äô practice and to plan educational programs to avoid the abuse of prescription medication. Medicine & Science in Sports & Exercise: May 2008 - Volume 40 - Issue 5 - pp 934-942 doi: 10.1249/MSS.0b013e3181666eb8 APPLIED SCIENCES: Physical Fitness and Performance Effect of Match-Related Fatigue on Short-Passing Ability in Young Soccer Players RAMPININI, ERMANNO; IMPELLIZZERI, FRANCO M.; CASTAGNA, CARLO; AZZALIN, ANDREA; BRAVO, DUCCIO FERRARI; WISL?òFF, ULRIK Abstract Purpose: To examine whether the fatigue accumulated during match play or determined by short bouts of high-intensity intermittent activities affect short-passing ability in junior soccer players. A further aim was to examine the influence of physical fitness as measured using the Yo-Yo Intermittent Recovery Test (YYIRT) on the changes in short-passing ability after a 5-min simulation of high-intensity activities (HIS). Methods: Sixteen players (mean ¬± SD: age 17.6 ¬± 0.5 yr, height 174 ¬± 7 cm, body mass 68 ¬± 6 kg) participated in the study. A quasi-experimental control-period design was used for the study. Short-passing ability was measured using the Loughborough Soccer Passing Test (LSPT). Players completed the LSPT in two sessions during the 1-wk control period, followed by two unofficial matches during which the LSPT was performed during and after the first and the second halves of the game. Furthermore, the change in LSPT performance was determined after 5 min of HIS. Results: A decline in LSPT performance was found during and after the game (P < 0.01). The accuracy of the LSPT decreased after the HIS. A significant correlation was found between the YYIRT scores and the decline in LSPT performance (accuracy, total time, total time with penalties) after HIS (r = -0.51 to -0.65; P < 0.05). Conclusions: This study showed that the fatigue developed during a match and after relatively short bouts of high-intensity intermittent activities has a detrimental effect on short-passing ability, and that the fatigue-related decline in technical proficiency for a given intensity is associated with the fitness level of the players. Prevention of Injuries Among Male Soccer Players A Prospective, Randomized Intervention Study Targeting Players With Previous Injuries or Reduced Function 1. Anders H. Engebretsen‚Ć,*, 2. Grethe Myklebust, PT, PhD‚Ć, 3. Ingar Holme, PhD‚Ć, 4. Lars Engebretsen, MD, PhD‚Ć,‚Ä°, and 5. Roald Bahr, MD, PhD‚Ć + Author Affiliations 1. From ‚ĆOslo Sports Trauma Research Center, Norwegian School of Sports Sciences, Oslo Norway, and the ‚Ä°Department of Orthopaedic Surgery, Ulleval University Hospital, University of Oslo, Oslo, Norway 1. Address correspondence to Anders H. Engebretsen, Oslo Sports Trauma Research Center, Norwegian School of Sports Science, PO Box 4014 Ullev?•l Stadion, N-0806 Oslo, Norway (e-mail: Anders.Engebretsen@nih.no). Abstract Background: This study was conducted to investigate whether the most common injuries in soccer could be prevented, and to determine if a simple questionnaire could identify players at increased risk. Hypothesis: Introduction of targeted exercise programs to male soccer players with a history of previous injury or reduced function in the ankle, knee, hamstring, or groin will prevent injuries. Study Design: Randomized controlled trial; Level of evidence, 2. Methods: A total of 508 players representing 31 teams were included in the study. A questionnaire indicating previous injury and/or reduced function as inclusion criteria was used to divide the players into high-risk (HR) (76%) and low-risk (LR) groups. The HR players were randomized individually into an HR intervention group or HR control group. Results: A total of 505 injuries were reported, sustained by 56% of the players. The total injury incidence was a mean of 3.2 (95% confidence interval [CI], 2.5‚Äì3.9) in the LR control group, 5.3 (95% CI, 4.6‚Äì6.0) in the HR control group (P = .0001 vs the LR control group), and 4.9 (95% CI, 4.3‚Äì5.6) in the HR intervention group (P = .50 vs the HR control group). For the main outcome measure, the sum of injuries to the ankle, knee, hamstring, and groin, there was also a significantly lower injury risk in the LR control group compared with the 2 other groups, but no difference between the HR intervention group and the HR control group. Compliance with the training programs in the HR intervention group was poor, with only 27.5% in the ankle group, 29.2% in the knee group, 21.1% in the hamstring group, and 19.4% in the groin defined as having carried out the minimum recommended training volume. Conclusion: The players with a significantly increased risk of injury were able to be identified through the use of a questionnaire, but player compliance with the training programs prescribed was low and any effect of the intervention on injury risk could not be detected. Effect of playing tactics on goal scoring in Norwegian professional soccer Authors: Albin Tenga a; Ingar Holme b; Lars Tore Ronglan a; Roald Bahr a Affiliations: a Norwegian School of Sport Sciences, Oslo b Department of Preventive Cardiology, Ullevaringl University Hospital, Oslo, Norway DOI: 10.1080/02640410903502774 Publication Frequency: 14 issues per year Published in: journal Journal of Sports Sciences, Volume 28, Issue 3 February 2010 , pages 237 - 244 Subject: Sport & Exercise Science; Formats available: HTML (English) : PDF (English) Article Requests: Order Reprints : Request Permissions * In order to give pricing details we need to know your country. Please register and/or sign in to identify your country. * Sign In Sign In * Online Sample Online Sample View Article: View Article (PDF) View Article (PDF) View Article (HTML) View Article (HTML) Abstract Methods that include an assessment of opponent interactions are thought to provide a more valid analysis of team match performance. The purpose of this study was to examine the effect of playing tactics on goal scoring by assessing opponent interactions in Norwegian elite soccer. The sample included 203 team possessions leading to goals (cases) and 1688 random team possessions (control group) from 163 of 182 (90%) matches played in the men's professional league during the 2004 season. Multidimensional qualitative data using ten ordered categorical variables were obtained to characterize each team possession. The proportion of goals scored during counterattacks (52%) was higher than during elaborate attacks (48%), while for the control group the proportion using elaborate attacks (59%) was higher than when using counterattacks (41%) (P = 0.002). Multiple logistic regression analyses showed that, for the main variable ‚Äúteam possession type‚Äù, counterattacks were more effective than elaborate attacks when playing against an imbalanced defence (OR = 1.64; 95% confidence interval: 1.03 to 2.61; P = 0.038). Assessment of opponent interactions is critical to evaluate the effectiveness of offensive playing tactics on the probability of scoring goals, and improves the validity of team match-performance analysis in soccer. Keywords: Validity; opponent interaction; logistic regression; goal scoring in soccer; match-performance analysis Measures of Exercise Intensity During Soccer Training Drills With Professional Soccer Players LITTLE, THOMAS; WILLIAMS, ALUN G. Collapse Box Abstract Recent evidence supports the use of certain soccer drills for combined technical and physical training. Therefore, it is important to be able to accurately monitor training intensity during soccer drills intended for physical development to allow the optimization of training parameters. Twenty-eight professional soccer players were assessed for heart rate (HR) and rating of perceived exertion (RPE) responses to 5 commonly used soccer training drills (2v2 to 8v8 drills). The responses of both HR and RPE differed significantly (p < 0.05) between the drills, generally showing an elevated response to drills involving lower player numbers. However, the 2v2 drill showed a significantly (p < 0.05) lower HR response (mean +/- SD: 88.7 +/- 1.2% HRmax) than 3v3 (91.2 +/- 1.3% HRmax) and 4v4 drills (90.2 +/- 1.6% HRmax). There was no significant correlation between the HR and RPE responses to the various drills (r = 0.60, p < 0.200). This poor relationship is probably because during the 2v2 drill, RPE was higher than during any of the other 6 drills, whereas HR was only fourth highest of the 6 drills. This demonstrates that HR and RPE are only poorly related during the intense drills used in this study, and that HR underestimates the intensity of the 2v2 drill. Heart rate demonstrated lower intersubject variability (1.3-2.2%) than RPE (5.1-9.9%). However, unlike HR, Borg 15-point RPE appears to be a valid marker of exercise intensity over a wide range of soccer training drills by maintaining validity in all drills and demonstrating acceptable intersubject variability. A combination of both HR- and RPE-based training load calculations appears optimal for use in soccer training. Journal of Movement Sciences & Sports Special Issue, No1, pp. 13-24 Musculoskeletal Assessment in Soccer: A Review Nader Rahnama1, Effat Bambaeichi2 1Associate Professor, Physical Education & Sport Sciences, University of Isfahan 2Assistant Professor, Physical Education & Sport Sciences, University of Isfahan Abstract Muscular strength is generally measured using either of the following methods, one repetition maximum (1- RM) of a weight-lifting exercise, a resisted maximal effort and portable or laboratory-based dynamometry. The 1- RM method refers to measurements of maximum strength using a strength training device such as a barbell or stationary weight-lifting machine. Dynamometry can be divided into two separate methods according to the muscle action involved. Isometric dynamometers assess the force exerted during static muscular actions typically associated with the back, legs and upper limb, e.g. hand (grip). The classical method of recording isometric muscle strength was cable tensiometry, later replaced by use of load cells and force transducers. In experimental studies, maximal voluntary contraction (MVC) is employed as the criterion for muscle strength, typically registered using strain-gauge assemblies. Such devices are relatively inexpensive and convenient to use in and out of the laboratory. Hand grip dynamometers are possibly the most widespread devices for measuring strength however there is concern regarding the strength in the muscle involved in isometric gripping and the generalisation to large muscle group or whole-body strength. The main limitation of such dynamometers is that they do not replicate sport specific activity. Dynamic strength assessment is the preferred method when assessing athletic performances opposed to isometric testing because of the large neural and mechanical differences between isometric and dynamic muscular action. This recommendation is supported by a number of studies that have found a poor association between isometric strength and dynamic performance in strength-based activities. Isokinetic dynamometry is used to assess dynamic muscle action whereby the velocity of limb movement is held constant throughout the range of movement and the resistance applied is equal to the muscular torque during the movement. Such a device allows accurate measurement of torque throughout many limb movements under concentric and eccentric muscle actions. With the subject maintaining a static position, the dynamometer also allows measurement during isometric muscle action. In order to measure absolute strength it is advised that a relatively low velocity is used to allow for production of maximal torque throughout the movement. The protocol used to establish maximum torque can vary, but this function is most often evaluated following several submaximal repetitions and from the first two or six maximal repetitions. Although such dynamometers allow for isolation of specific muscle groups through a single joint motion, they are limited in their representation of typical sports activities. In this paper some important isokinetic parameters relevant to soccer will be discussed Int J Sports Physiol Perform. 2007 Sep;2(3):239-49. Acute effects of soccer training on white blood cell count in elite female players. Avloniti AA, Douda HT, Tokmakidis SP, Kortsaris AH, Papadopoulou EG, Spanoudakis EG. Dept of Physical Education and Sport Science, Democritus University of Thrace, Alexandroupoli, Greece. PURPOSE: To investigate the acute changes in leukocyte number and cortisol after a single bout of soccer training. METHODS: Ten elite female national-team soccer players and 8 nonathletes participated in the study. The duration of the exercise was 2 h, and it was performed at an intensity of 75% of maximal heart rate (HRmax). Blood samples were taken before, immediately after, and 4 h after a soccer training session to determine total white blood cells; the subsets of neutrophils, lymphocytes, monocytes, eosinophils, and basophils; and cortisol. At the same time, blood samples were obtained from nonathletes who refrained from exercise. RESULTS: Data analysis indicated a significant increase in total white blood cells in the athletes postexercise (P < .001). The leukocytosis was still evident after 4 h of recovery (78% higher than the preexercise values), and there was a significant difference between athletes and nonathletes (P < .001). This leukocytosis was primarily caused by neutrophilia-there were no significant differences in lymphocytes after the end of exercise or between the 2 groups (P > 0.05). In addition, there was a statistically significant difference in cortisol concentration between athletes and nonathletes after the exercise (P < .001). CONCLUSION: These findings revealed that the single bout of soccer training at an intensity of 75% of HRmax induced leukocytosis without affecting the lymphocyte count in elite female athletes and probably the effectiveness of cellular components of adaptive immunity. Coaches should provide adequate time (>4 h) until the next exercise session. Fluid and electrolyte balance in elite male football (soccer) players training in a cool environment R.J. MAUGHAN,1* S.M. SHIRREFFS,1 S.J. MERSON1 and C.A. HORSWILL2 1School of Sport and Exercise Sciences, Loughborough University, Loughborough LE11 3TU, UK and 2Gatorade Sports Science Institute, Barrington, IL 60010, USA Accepted 30 April 2004 There are few data in the published literature on sweat loss and drinking behaviour in athletes training in a cool environment. Sweat loss and fluid intake were measured in 17 first-team members of an elite soccer team training for 90 min in a cool (58C, 81% relative humidity) environment. Sweat loss was assessed from the change in body mass after correction for the volume of fluid consumed. Sweat electrolyte content was measured from absorbent patches applied at four skin sites. Mean ( + s) sweat loss during training was 1.69 +0.45 l (range 1.06 ‚Äì 2.65 l). Mean fluid intake during training was 423 +215 ml (44 ‚Äì 951 ml). There was no apparent relationship between the amount of sweat lost and the volume of fluid consumed during training (r2 = 0.013, P = 0.665). Mean sweat sodium concentration was 42.5 +13.0 mmol ?ó l 71 and mean sweat potassium concentration was 4.2 + 1.0 mmol ?ó l 71 . Total salt (NaCl) loss during training was 4.3 +1.8 g. The sweat loss data are similar to those recorded in elite players undergoing a similar training session in warm environments, but the volume of fluid ingested is less The effects of multidirectional soccer-specific fatigue on markers of hamstring injury risk Journal of Science and Medicine in Sport, Volume 13, Issue 1, Pages 120-125 K. Small, L. McNaughton, M. Greig, R. Lovell You can get the full-text article here... ...if you are: * healthcare practitioner * interested in pay-per-view article purchase * visitor or subscriber to the website * student or faculty member * researcher or librarian * visitor or subscriber to the journal website Learn which websites I use (cookies required) Update your website selections Abstract The purpose of this work was to investigate the effect of multidirectional soccer-specific fatigue on hamstring muscle strength and angle of peak torque. Sixteen male semi-professional soccer players (mean¬±S.D.: age: 21.3¬±2.9 years; height 185.0¬±8.7cm; body mass 81.6¬±6.7kg) completed the SAFT90, a multidirectional, intermittent 90-min exercise protocol based on data from English Championship soccer matches. Prior to exercise (t0), at half-time (t45) and post-exercise (t105), subjects performed three maximal dominant limb isokinetic contractions (Biodex, System 3) at 120¬?s‚àí1 through a 90¬? range for concentric and eccentric knee flexors and concentric knee extensors. Analysis of variance revealed significant time dependant reductions in gravity corrected eccentric hamstring peak torque, and consequently in the functional hamstring:quadriceps ratio (P<0.01). Eccentric hamstring peak torque decreased significantly during each half (t0: 272.0¬±43.2; t45: 240.4¬±43.3; t105: 226.3¬±45.7Nm). The functional hamstring:quadriceps ratio also decreased significantly during each half (t0: 116.6¬±21.2; t45: 107.1¬±17.6; t105: 98.8¬±20.3%). There were no significant changes in concentric hamstring or quadriceps peak torque observed during SAFT90 (P>0.05). Data analysis also revealed significant differences for Angle of Peak Torque for eccentric hamstrings (P<0.05) which was significantly higher at the end of each half (t45: 37¬±15; t105: 38¬±18¬?) than the pre-exercise value (t0: 28¬±12¬?). There was a time dependant decrease in peak eccentric hamstring torque and in the functional strength ratio which may have implications for the increased predisposition to hamstring strain injury during the latter stages of match-play. Summary International Journal of Neuroscience 2009, Vol. 119, No. 1, Pages 76-87 , DOI 10.1080/00207450802480069 Neural Correlates of Winning and Losing While Watching Soccer Matches Hye Ju Park‚Äå1, Ren Xi Li‚Äå2, Jingu Kim‚Äå3‚Ć, Sung Woon Kim‚Äå1, Doo Hwan Moon‚Äå4, Myung Hwa Kwon‚Äå1 and Woo Jong Kim‚Äå1 1Performance Psychology Laboratory, Kyungpook National University, Republic of Korea 2Department of Kinesiology, University of PetroleumChina, China 3Brain Science Engineering Institute, Kyungpook National University, Republic of Korea 4Department of Physical Education, Kyungpook National University, Republic of Korea ‚ĆCorrespondence: Jingu Kim, Department of Physical Education, Kyungpook National University, 1370, Sanghyukdong Bukgu, Daegu, 702-701, Republic of Korea The purpose of this study was to examine the emotions experienced by spectators when their favorite team wins or loses a soccer match using fMRI. Those who watched winning scenes showed activation of the right and left occipital lobes, left temporal lobe, left limbic lobe, middle occipital gyrus, superior temporal gyrus, guneus, and uncus. Those who watched losing scenes showed activation of the right frontal lobe and right limbic lobe. This result suggests that emotional suppression is much stronger in negative emotional responses than in positive responses. Journal of Strength and Conditioning Research: January 2008 - Volume 22 - Issue 1 - pp 283-292 doi: 10.1519/JSC.0b013e31815f302a Original Research A Test to Evaluate the Physical Impact on Technical Performance in Soccer Rostgaard, Thomas; Iaia, F Marcello; Simonsen, Dennis S; Bangsbo, Jens Collapse Box Abstract The aim of the study was to develop and examine a test for evaluation of the physical and technical capacity of soccer players. Fourteen youth elite (YE) and seven sub-elite (SE) players performed a physical and technical test (PT-test) consisting of 10 long kicks interspersed with intense intermittent exercise. In addition, a control test (CON-test) without intense exercise was performed. In both cases, the test result was evaluated by the precision of the 10 kicks. The players also performed the Yo-Yo intermittent recovery test level 2 (Yo-Yo IR2). For the SE-players, blood samples were obtained and heart rate was measured before, during, and after the PT-test. A muscle biopsy was collected before and after the PT-test. Coefficient of variation for the PT- and CON-test was 11.7% and 16.0%, respectively. The YE-players performed better (P < 0.05) than the SE-players in both the PT-test (16.3 ¬± 0.8 (¬±SE) vs. 13.2 ¬± 1.3 points) and CON-test (24.4 ¬± 0.7 vs. 20.5 ¬± 1.6 points) with no difference in the relative PT-test result (PT-test/CON-test: 0.63 ¬± 0.03 vs. 0.64 ¬± 0.03). Summed performance of the first 5 repetitions was higher (P < 0.05) than for the last 5 repetitions (8.4 ¬± 0.6 vs. 6.9 ¬± 0.5; n = 20). The YE-players performed better (P < 0.05) than the SE-players during Yo-Yo IR2 (1023 ¬± SE vs. 893 ¬± SE m). The mean heart rate during the PT-test was 173 ¬± 4 b.p.m. (90 ¬± 2% of HRmax). Blood lactate, glucose, and ammonia reached 5.6 ¬± 0.7, 6.2 ¬± 0.6 mmol L-1, and 76 ¬± 11umol L-1 at the end of the test, respectively. After the test muscle CP, glycogen and lactate was 52.9 ¬± 6.6, 354 ¬± 39, and 25.3 ¬± 5.9 mmol kg-1 d.w., respectively. In summary, the PT-test can be used to evaluate a soccer player's technical skills under conditions similar to intense periods of a soccer game. Journal of Strength and Conditioning Research: August 2009 - Volume 23 - Issue 5 - pp 1370-1377 doi: 10.1519/JSC.0b013e3181a4e82f Original Research Seasonal Variation in Physiological Fitness of a Semiprofessional Soccer Team Caldwell, Brian P; Peters, Derek M Abstract Caldwell, BP and Peters, DM. Seasonal variation in physiological fitness of a semiprofessional soccer team. J Strength Cond Res 23(5): 1370-1377, 2009-The purpose of this study was to investigate seasonal variations in physiological fitness of semiprofessional soccer players over a 12-month period. Thirteen male players were tested 5 times over a 12-month period using bioelectrical impedance, a 20-m multistage fitness test, countermovement standing vertical jump, 15-m sprint test, Illinois agility test, and sit and reach test. Significant deconditioning was apparent in all fitness variables from end of season one season to prepreseason training of the next season. Aerobic fitness, vertical jump, percent body fat, agility, and sprint performance improved from prepreseason to midseason. Significant decreases in aerobic fitness and the cessation of significant increases in vertical jump, sprint, and agility performance were shown from midseason onward. No differences between the fitness components at the end of season one and the end of season two were identified. The deconditioning apparent in all fitness parameters during the off season, together with progressive improvement in most from postpreseason to midseason would support these parameters as sport-specific fitness requirements. Such improvements suggest that the short-term demands of playing and training in the first half of the season develop fitness and these trends are similar to those for professional players. Body fat was also shown to be detrimental to sprint performance throughout the 12-month period. Further research is needed to identify if the plateau in fitness from midseason is the result of attaining the required level of fitness, fatigue, allied training, or even relative success. Enhancing off-season training may enable yearly fitness increases by at least maintaining fitness levels for the next year's preseason. Journal of Strength and Conditioning Research: October 2009 - Volume 23 - Issue 7 - pp 1960-1967 doi: 10.1519/JSC.0b013e3181b8666e Original Research The Effects of Postactivation Potentiation on Sprint and Jump Performance of Male Academy Soccer Players Till, Kevin A; Cooke, Carlton Collapse Box Abstract Till, KA and Cooke, C. The effects of postactivation potentiation on sprint and jump performance of male academy soccer players. J Strength Cond Res 23(7): 1960-1967, 2009-The purpose of this investigation was to evaluate the postactivation potentiation (PAP) effects of both dynamic and isometric maximum voluntary contractions (MVCs) on sprint and jump performance and establish whether PAP methods could be used effectively in warm up protocols for soccer players. Twelve male soccer players performed 4 warm up protocols in a cross-over, randomized, and counterbalanced design. In addition to a control warm up, subjects performed deadlift (5 repetitions at 5 repetitions maximum), tuck jump (5 repetitions), and isometric MVC knee extensions (3 repetitions for 3 s) as PAP treatments in an otherwise identical warm up protocol. After each treatment, the subjects underwent 3 10 m and 20 m sprints 4, 5, and 6 minutes post-warm up and 3 vertical jumps (VJ) at 7, 8, and 9 minutes post-warm up. Repeated measures analysis of variance showed no significant differences in the first 10 m (p = 0.258) and 20 m (p = 0.253) sprint and VJ (p = 0.703) performance and the average 10 m (p = 0.215), 20 m (p = 0.388), and VJ (p = 0.529) performance between conditions. There were also no significant differences in performance responses between the strongest and weakest subjects, but large variations in individual responses were found between the subjects. The findings suggest that there was no significant group PAP effect on sprint and jump performance after dynamic and isometric MVCs compared with a control warm up protocol. However, the large variation in individual responses (‚àí7.1% to +8.2%) suggests PAP should be considered on an individual basis. Factors such as method, volume, load, recovery, and interindividual variability of PAP must be considered in the practical application of PAP and the rigorous research design of future studies to evaluate the potential for performance enhancement. The Nordic Eccentric Hamstring Exercise for Injury Prevention in Soccer Players PhD, CSCS, Adam Sayers; Sayers, Brandi-Eveland PhD, CSCS Collapse Box Abstract ECCENTRIC HAMSTRING MUSCLE ACTIONS ARE INVOLVED IN SEVERAL MOVEMENTS IN THE GAME OF SOCCER. RECENT STUDIES HAVE INDICATED THAT THE NORDIC HAMSTRING EXERCISE IS AN EFFECTIVE WAY OF ECCENTRICALLY STRENGTHENING THE HAMSTRINGS IN SOCCER PLAYERS, RESULTING IN REDUCED INJURY RISK AND IMPROVED PERFORMANCE. How Do Expert Soccer Players Encode Visual Information to Make Decisions in Simulated Game Situations? Authors: Poplu, G?©rald; Ripoll, Hubert; Mavromatis, S?©bastien; Baratgin, Jean Source: Research Quarterly for Exercise and Sport, Volume 79, Number 3, September 2008 , pp. 392-398(7) Publisher: American Alliance for Health, Physical Education, Recreation & Dance Purchase options The full text electronic article is available for purchase. You will be able to download the full text electronic article after payment. $37.00 plus tax Refund Policy Purchase later OR Credit/debit card Institutional payment account More about this publication? * Research Quarterly for Exercise and Sport (RQES) is a highly respected professional journal offering the latest research in the art and science of human movement studies. This comprehensive professional journal features articles and research notes en... more Research Quarterly for Exercise and Sport (RQES) is a highly respected professional journal offering the latest research in the art and science of human movement studies. This comprehensive professional journal features articles and research notes encompassing such topic areas as biomechanics, epidemiology, growth and motor development, motor control and learning, measurement and evaluation, physiology, pedagogy, psychology, history and philosophy, and sociology/cultural anthropology. An excellent research tool, this journal is a must-have for researchers and university students preparing for careers in exercise and sport science. RQES works with the Research Consortium to bring readers the up-to-date research in areas related to movement science. * Editorial Board * Information for Authors * Submit a Paper * Subscribe to this Title * Membership Information * Information for Advertisers * Terms & Conditions * Abstracts of Articles * Author and Subject More like this? * In this: publication * By this: publisher * In this Subject: Anatomy & Physiology , Public Health , Psychology * By this author: Poplu, G?©rald ; Ripoll, Hubert ; Mavromatis, S?©bastien ; Baratgin, Jean * < previous article * | * next article > * | * view table of contents Content Key: Free Content - Free New Content - New Open Access Content - Open Access Subscribed Content - Subscribed Free Trial Content - Free Trial Click here to find out more! Abstract: The aim of this study was to determine what visual information expert soccer players encode when they are asked to make a decision. We used a repetition-priming paradigm to test the hypothesis that experts encode a soccer pattern's structure independently of the players' physical characteristics (i.e., posture and morphology). The participants were given either realistic (digital photos) or abstract (three-dimensional schematic representations) soccer game patterns. The results showed that the experts benefited from priming effects regardless of how abstract the stimuli were. This suggests that an abstract representation of a realistic pattern (i.e., one that does not include visual information related to the players' physical characteristics) is sufficient to activate experts' specific knowledge during decision making. These results seem to show that expert soccer players encode and store abstract representations of visual patterns in memory. Int J Sports Med. 2010 Mar;31(3):174-179. Epub 2010 Feb 15. Soccer Endurance Development in Professionals. Roescher CR, Elferink-Gemser MT, Huijgen BC, Visscher C. University Medical Center Groningen, University of Groningen, Center for Human Movement Sciences, Groningen, The Netherlands. The development of intermittent endurance capacity, its underlying mechanisms and role in reaching professional level in soccer was investigated. The sample included 130 talented youth soccer players aged 14-18, who became professional (n=53) or non-professional (n=77) players in adulthood. In total 229 Interval Shuttle Run Test (ISRT) scores were taken over five years. Players who became professionals improved from age 14 to 18 on average from 68 to 109 runs in contrast to players who remained amateurs (from 73 to 93 runs). A longitudinal model was developed using linear mixed models procedures. Intermittent endurance capacity can be predicted adequately with a two-level hierarchical model (p<0.05). Anthropometric characteristics and playing position did not improve model fit (p>0.05). The estimated ISRT score necessary to reach professional level is: ISRT=-375.77-62.89+(51.20+4.20) * age-1.50 * age (2)+3.54 * hours of soccer training+1.18 * additional training hours. In conclusion, intermittent endurance capacity improves with age in talented youth soccer players. From age 15 players who reached the professional level show a faster development than their non-professional counterparts. This development is positively influenced by both soccer specific and additional training. ¬© Georg Thieme Verlag KG Stuttgart ¬? New York. Psychological Momentum within Competitive Soccer: Players' Perspectives Authors: Martin I. Jones a; Chris Harwood a Affiliation: a Loughborough University, United Kingdom DOI: 10.1080/10413200701784841 Publication Frequency: 4 issues per year Published in: journal Journal of Applied Sport Psychology, Volume 20, Issue 1 January 2008 , pages 57 - 72 Subjects: Sport Psychology; Sports Psychology; Formats available: HTML (English) : PDF (English) Article Requests: Order Reprints : Request Permissions * In order to give pricing details we need to know your country. Please register and/or sign in to identify your country. * Sign In Sign In * Online Sample Online Sample View Article: View Article (PDF) View Article (PDF) View Article (HTML) View Article (HTML) Abstract The purpose of this investigation was to identify and examine perceptions of psychological momentum from the perspective of competing players in a team sport to provide applied implications for athletes, coaches, and sport psychology practitioners. Participants were five university soccer players who had played in the National British University Sports Association competition during the previous season. Data were collected via three phases of formal interviews, which were supplemented by a comprehensive member check (Lincoln & Guba, 1985). Furthermore, transcribed interviews were subjected to an inductive content analysis. Participants described a range of psychological momentum triggers and outcomes based on their experiences of positive and negative psychological momentum. Moreover, participants described strategies used to develop and maintain positive psychological momentum and strategies to overcome negative psychological momentum. Findings are discussed in relation to applied implications for athletes, coaches, and sport psychology consultants operating in team sport settings. Carbohydrate ingestion and soccer skill performance during prolonged intermittent exercise Authors: Ajmol Ali a; Clyde Williams b Affiliations: a Institute of Food, Nutrition and Human Health, Massey University, Auckland, New Zealand b School of Sport and Exercise Sciences, Loughborough University, Loughborough, UK DOI: 10.1080/02640410903334772 Publication Frequency: 14 issues per year Published in: journal Journal of Sports Sciences, Volume 27, Issue 14 December 2009 , pages 1499 - 1508 First Published on: 04 December 2009 Subject: Sport & Exercise Science; Formats available: HTML (English) : PDF (English) Article Requests: Order Reprints : Request Permissions * In order to give pricing details we need to know your country. Please register and/or sign in to identify your country. * Sign In Sign In * Online Sample Online Sample View Article: View Article (PDF) View Article (PDF) View Article (HTML) View Article (HTML) Abstract The aim of this study was to investigate the effect of ingesting a carbohydrate-electrolyte solution, during the 90-min Loughborough Intermittent Shuttle Test, on soccer skill performance. Seventeen male soccer players ingested either a 6.4% carbohydrate-electrolyte solution or placebo solution equivalent to 8 ml ¬? kg-1 body mass before exercise and 3 ml ¬? kg-1 body mass after every 15 min of exercise, in a double-blind randomized cross-over design, with the trials separated by 7 days. The evening before the main trial, the participants performed glycogen-reducing exercise on a cycle ergometer (80 min at 70%[Vdot]O2max) and were then fed a low-carbohydrate meal. After a 12-h overnight fast, they performed The Loughborough Soccer Passing Test before and after every 15 min of exercise. Analysis of the combined skill test data showed a significant time effect (P = 0.001) with differences between 0-45 and 75-90 min (P < 0.05). There was a 3% reduction in skill performance from before to after exercise in the carbohydrate-electrolyte trial, whereas in the placebo trial the decrease was 14% (P = 0.07). In conclusion, skill performance during the simulated soccer activity appeared to deteriorate in the last 15-30 min of exercise. However, providing 52 g ¬? h-1 carbohydrate during exercise showed a tendency to better maintain soccer skill performance than a taste-matched placebo. nt J Sport Nutr Exerc Metab. 2007 Oct;17(5):421-32. Nutritional adequacy of different menu settings in elite Spanish adolescent soccer players. Garrido G, Webster AL, Chamorro M. Dept. of Human Performance, National Institute of Physical Education, Madrid, Spain. The article describes a study that evaluated the adequacy of 2 different menu settings in a group of elite adolescent Spanish soccer players. Five-day food intake was assessed on 2 occasions, while athletes were consuming a flexible "buffet-style" diet (B; n = 33) and a fixed "menu-style" diet (M; n = 29). For all principal meals of the day food weighing was performed, and snacks were recorded by self-report. M provided significantly higher total energy and carbohydrate intakes than B. Breakfast and snacks both provided more energy in M. Calories obtained from fat were excessive in both settings. Calcium and vitamin D were below recommendations in B but not in M. Fiber, magnesium, folate, vitamin A, and vitamin E intake fell below recommended values in both settings. M provided significantly greater quantities of magnesium and vitamins D and E. Both feeding options were far from optimal in satisfying current scientifically based recommendations for active adolescents The influence of soccer-specific activity on the kinematics of an agility sprint Author: Greig, Matt1 Source: European Journal of Sport Science, Volume 9, Number 1, January 2009 , pp. 23-33(11) Publisher: Taylor and Francis Ltd Purchase options The full text electronic article is available for purchase. You will be able to download the full text electronic article after payment. $42.75 plus tax Refund Policy Purchase later OR Credit/debit card Institutional payment account More like this? * In this: publication * By this: publisher * By this author: Greig, Matt * < previous article * | * next article > * | * view table of contents Content Key: Free Content - Free New Content - New Open Access Content - Open Access Subscribed Content - Subscribed Free Trial Content - Free Trial Abstract: The aim of this study was to investigate the influence of soccer-specific fatigue on the kinematics of an agility sprint. Ten male professional soccer players (age 24.7¬±4.4 years, body mass 77.1¬±8.3 kg) completed an intermittent treadmill protocol replicating the activity profile of match-play, comprising two 45-min halves separated by a 15-min passive half-time interval. Pre-exercise and at 15-min intervals each player completed an agility sprint that consisted of a 180¬? cutting manoeuvre. Knee joint kinematics in the frontal and sagittal planes were determined for both the support and turning leg using a nine-camera automated motion analysis system operating at 200 Hz. During the penultimate foot contact, knee kinematics were characterized by joint flexion and increased varus alignment. Knee flexion at touchdown decreased significantly (P<0.05) as a function of exercise duration from 57.4¬±15.5¬? before exercise to 37.0¬±5.9¬? at the end of the second half. The range of joint movement during the knee flexion phase increased significantly during the first half (T45=66.6¬±18.2¬?) and remained elevated during the second half (T75=66.4¬±18.1¬?; T90=65.7¬±20.4¬?; T105=70.2¬±19.4¬?) relative to pre-exercise values (51.8¬±18.8¬?). During the final foot contact, knee kinematics were also characterized by flexion and increased varus alignment. Knee flexion at touchdown decreased during each half, with the knee angle at the end of the first half (30.6¬±7.0¬?) significantly (P=0.02) straighter than before exercise (39.5¬±6.3¬?), and significantly straighter at the end of the second half (30.2¬±2.9¬?) than after the half-time interval (37.7¬±7.8¬?) or before exercise. The range of knee flexion during ground contact increased significantly during each half. The range of knee varus during flexion changed from a varus displacement during the first 15 min to a valgus displacement thereafter. Peak valgus observed at the end of each half (T45=4.7¬±7.9¬?; T105=6.9¬±7.4¬?) was significantly (P<0.05) greater than before exercise. The range of valgus movement during knee extension was greatest following the passive half-time interval (T60=6.2¬±7.3¬?), and tended to increase throughout the second half. Prolonged exposure to soccer-specific intermittent exercise therefore induced changes in knee kinematics that may have implications for injury incidence. The increased varus alignment and time-dependent decrease in knee flexion at touchdown represent two potential mechanisms for increased injury risk. J Sports Med Phys Fitness. 2004 Jun;44(2):119-25. Concentric quadriceps and hamstrings isokinetic strength in volleyball and soccer players. Magalh?£es J, Oliveira J, Ascens?£o A, Soares J. Department of Sports Biology, Faculty of Sport Sciences and Physical Education, University of Porto, Porto, Portugal. jmaga@fcdef.up.pt AIM: Muscular strength is one of the most important components of sport, both for high performance and for injury prevention. One of the most used methods to assess strength muscle balance between dominant (D)/non-dominant (ND) and antagonist/agonist is isokinetic testing. The main purpose of the present study was to describe and to compare isokinetic strength profiles (peak torque, bilateral strength differences between D/ND leg (BD) and hamstrings/quadriceps (H/Q) ratio) in athletes of different sports and positional roles. METHODS: Twenty-eight elite volleyball players and 47 pro soccer players (goalkeepers, n = 5; full-backs, n = 7; defenders, n = 10; midfielders, n = 15; forwards, n = 10) were evaluated using an isokinetic dynamometer (Biodex-System 2). Maximal gravity corrected concentric peak torque of knee extensor and flexor muscles were measured at angular velocities of 360 degrees x s(-1) (6.28 rad x s(-1)) and 90 degrees x s(-1) (1.57 rad x s(-1)). RESULTS: No significant BD were found between soccer and volleyball players with exception of hamstrings at 90 degrees x s(-1) (soccer: 10.6 +/- 8.0% vs volleyball: 6.9 +/- 5.5%). The H/Q ratio was significantly lower in volleyball players at 90 degrees x s(-1) (D: soccer 57.4 +/- 6.7% vs volleyball 50.4 +/- 7.2%; ND: soccer: 56.1 +/- 8.2% vs volleyball: 50.5 +/- 6.4%). No significant differences were found for BD and H/Q ratio in soccer players of different positional roles. CONCLUSION: In general, soccer and volleyball players do not seem to be different concerning BD although a significant difference was observed in hamstrings at 90 degrees x s(-1). Moreover, our data suggest that specific demands of these sports and the different positional roles in soccer did not induce bilateral leg imbalances. However, sport demands seem to influence isokinetic concentric H/Q ratio. Work-rate of substitutes in elite soccer: A preliminary study Journal of Science and Medicine in Sport, Volume 13, Issue 2, Pages 253-255 C. Carling, V. Espi?©, F. Le Gall, J. Bloomfield, H. Jullien You can get the full-text article here... ...if you are: * healthcare practitioner * interested in pay-per-view article purchase * visitor or subscriber to the website * student or faculty member * researcher or librarian * visitor or subscriber to the journal website Learn which websites I use (cookies required) Update your website selections Abstract The aim of this study was to investigate the work-rate of substitutes in professional soccer. A computerised player tracking system was used to assess the work-rates of second-half substitutes (11 midfielders and 14 forwards) in a French Ligue 1 club. Total distance, distance covered in five categories of movement intensity and recovery time between high-intensity efforts were evaluated. First- and second-half work-rates of the replaced players were compared. The performance of substitutes was compared to that of the players they replaced, to team-mates in the same position who remained on the pitch after the substitution and in relation to their habitual performances when starting games. No differences in work-rate between first- and second-halves were observed in all players who were substituted. In the second-half, a non-significant trend was observed in midfield substitutes who covered greater distances than the player they replaced whereas no differences were observed in forwards. Midfield substitutes covered a greater overall distance and distance at high-intensities (p<0.01) and had a lower recovery time between high-intensity efforts (p<0.01) compared to other midfield team-mates who remained on the pitch. Forwards covered less distance (p<0.01) in their first 10-min as a substitute compared to their habitual work-rate profile in the opening 10-min when starting matches while this finding was not observed in midfielders. These findings suggest that compared to midfield substitutes, forward substitutes did not utilise their full physical potential. Further investigation is warranted into the reasons behind this finding in order to optimise the work-rate contributions of forward substitutes. Hematological parameters and anaerobic threshold in Brazilian soccer players throughout a training program A. S. R. SILVA, V. SANTHIAGO, M. PAPOTI, C. A. GOBATTO Department of Physical Education, Bioscience Institute, University of Sao Paulo State (Unesp), Rio Claro, Sao Paulo, Brazil Correspondence to A. S. R. Silva, Av. Miguel Damha, 1000, Residencial Damha I, unidade 214, Jardim Guanabara, 13565-814, Sao Carlos, Sao Paulo, Brazil. Tel.: +55 1633067131; Fax: +55 1633726569; E-mail: adelinosanchez@hotmail.com Copyright Journal compilation ¬© 2008 Blackwell Publishing Ltd KEYWORDS Athletes ‚Ä¢ soccer ‚Ä¢ hematological parameters ‚Ä¢ anaerobic threshold ABSTRACT Abstract Introduction Materials and methods Results Discussion Acknowledgements References We assessed the responses of hematological parameters and their relationship to the anaerobic threshold of Brazilian soccer players during a training program. Twelve athletes were evaluated at the beginning (week 0, T1), in the middle (week 6, T2), and at the end (week 12, T3) of the soccer training program. On the first day at 7:30 am, before collecting the blood sample at rest for the determination of the hematological parameters, the athletes were conducted to the anthropometric evaluation. On the second day at 8:30 am, the athletes had their anaerobic threshold measured. Analysis of variance with Newman‚ÄìKeuls'post hoc was used for statistical comparisons between the parameters measured during the soccer training program. Correlations between the parameters analyzed were determined using the Pearson's correlation coefficient. Erythrocytes concentration, hemoglobin, and hematocrit were significantly increased from T1 to T2. The specific soccer training program led to a rise in erythrocytes, hemoglobin, and hematocrit from T1 to T2. We assumed that these results occurred due to the plasma volume reduction and may be explained by the soccer training program characteristics. Furthermore, we did not observe any correlation between the anaerobic threshold and the hematological parameters. |