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Performance Area => Peer Reviewed Studies Discussion => Topic started by: adarqui on June 28, 2009, 02:10:47 am
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Anything related to 400m or 200m sprints.
x. Fatigue and changes of ATP, creatine phosphate, and lactate during the 400-m sprint.
Fatigue during the 400-m sprint was studied by measuring muscle ATP, creatine phosphate (CP), lactate (M-La), and blood lactate (B-La) in six male runners before and after four experimental sprints (100, 200, 300, and 400 m). During the first 100 m, muscle CP decreased from 15.8 +/- 1.7 to 8.3 +/- 0.3 mmol/kg while M-La increased to 3.6 +/- 0.4 mmol/kg. After 200 m the CP had decreased to 6.5 +/- 0.5 mmol/kg and M-La had increased to 8.3 +/- 1.1 mmol/kg. At the end of the 400 meters, ATP and CP concentrations had decreased by 27% and 89%, respectively, and M-La had increased to 17.3 +/- 0.9 mmol/kg. It was concluded that after 200 m the speed of running decreased, although CP was not depleted and lactate concentration was not at maximum level. Complete fatigue occurred when CP stores were depleted and B-La and M-La attained an individual maximum.
x. Velocity and Stride Parameters of World-Class 400-Meter Athletes Compared With Less Experienced Runners
The purpose of this study was to determine, based on the time course of the velocity and stride pattern recorded in each 50-m segment of a 400-m competition, whether elite 400-m runners present the same pacing strategy as less successful athletes. Based on video data, 3 different levels of performance were analyzed: world-class, national, and regional levels for both sexes, with each of the 6 groups comprising 5 subjects. The peak velocity was reached by all athletes between the 50- and 100-m marks with mean values of 8.96 and 10.12 m·s-1 for the 5 best women and men, respectively. Peak frequencies were observed in the second and third 50-m segments; peak values were 3.99 ± 0.13 for the world-class women (WWC) and 4.12 ± 0.19 for the men (MWC). A stride length of 2.29 ± 0.04 was observed for the WWC and 2.53 ± 0.08 for the MWC. The better athletes were able to achieve higher absolute and relative velocities (97.6 ± 0.5 [MWC] and 96.3 ± 0.7% [WWC] of their best performance for 200 m) at the 200-m mark compared with the lower-level athletes. Furthermore, the fatigue index was calculated as 22.99, 14.43, and 13.91% for the world-class, national, and regional levels, respectively. In summary, world-class runners adopt a more aggressive pacing strategy and demonstrate greater fatigue than the less experienced runners; this might indicate a greater mental commitment and/or a better capacity to run under fatigue.
x. Blood Lactate Changes during Isocapnic Buffering in Sprinters and Long Distance Runners
This study was carried out to compare blood lactate changes in isocapnic buffering phase in an incremental exercise test between sprinters and long distance runners, and to seek the possibility for predicting aerobic or anaerobic potential from blood lactate changes in isocapnic buffering phase. Gas exchange variables and blood lactate concentration ([lactate]) in six sprinters (SPR) and nine long distance runners (LDR) were measured during an incremental exercise test (30 W·min-1) up to subject's voluntary exhaustion on a cycle ergometer. Using a difference between [lactate] at lactate threshold (LT) and [lactate] at the onset of respiratory compensation phase (RCP) and the peak value of [lactate] obtained during a recovery period from the end of the exercise test, the relative increase in [lactate] during the isocapnic buffering phase ([lactate]ICBP) was assessed. The [lactate] at LT (mean ± SD) was similar in both groups (1.36 ± 0.27 for SPR vs. 1.24 ± 0.24 mmol·l-1 for LDR), while the [lactate] at RCP and the peak value of [lactate] were found to be significantly higher in SPR than in LDR (3.61 ± 0.33 vs. 2.36 ± 0.45 mmol·l-1 for RCP, P<0.001, 10.18 ± 1.53 vs. 8.10 ± 1.61 mmol·l-1 for peak, P<0.05). The [lactate]ICBP showed a significantly higher value in SPR (22.5 ± 5.9%, P<0.05) compared to that in LDR (14.2 ± 5.0%) as a result of a twofold greater increase of [lactate] from LT to RCP (2.25 ± 0.49 for SPR vs. 1.12 ± 0.39 mmol·l-1 for LDR). In addition, the [lactate]ICBP inversely correlated with oxygen uptake at LT (VO2LT, r=-0.582, P<0.05) and maximal oxygen uptake (VO2max, r=-0.644, P<0.01). The results indicate that the [lactate]ICBP is likely to give an index for the integrated metabolic, respiratory and buffering responses at the initial stage of metabolic acidosis derived from lactate accumulation.
x. Peak blood lactate after short periods of maximal treadmill running
Summary Blood lactate was determined in 19 untrained subjects after maximal treadmill exercise lasting for about 1 min. It was found that blood lactate increases after exercise, reaching a maximum level 6–9 min after the cessation of exercise, and the average time for the appearance of the peak blood lactate concentration was 7.65 min. Peak blood lactate concentration at 7.65 min (CLA7.65), which was calculated by substituting t (7.65) into the equation for the lactate recovery curve for each subject, agreed well with the observed peak blood lactate concentration (r=0.98, p<0.001). In addition, correlations of r=–0.65, r=–0.78, r=–0.79 were found between CLA7.65 and the running times of 100 m, 200 m, and 400 m sprints, respectively. These results suggest that CLA7.65 may be used as a valid indicator of anaerobic work capacity in man.
x. Leg muscle pH following sprint running
In an effort to compare the disturbances in leg muscle pH during sprint running, muscle biopsies were obtained from the gastrocnemius and vastus lateralis muscles of six healthy men (three endurance-trained and three nonendurance-trained) before and after a treadmill sprint run (TSR) to fatigue (54-105 s) at roughly 125% of their aerobic capacities. Following the TSR, repeated blood samples were taken from a hand vein and later analyzed for pH, Pco2, and lactic acid (HLa). The muscle specimens were analyzed in duplicate for pH and HLa. Resting-muscle pH was 7.03 +/- 0.02 ([latin capital V with dot above] +/- SE) and 7.04 +/- 0.01 for the gastrocnemius and vastus lateralis muscles, respectively. At the termination of the TSR, the pH in these muscles was 6.88 +/- 0.05 and 6.86 +/- 0.03, respectively. After a 400-m timed run on the track, the pH in the gastrocnemius of four of the subjects averaged 6.63 +/- 0.03, while blood pH and HLa were 7.10 +/- 0.03 and 12.3 mM, respectively. Although no differences in pH and HLa were observed between the vastus lateralis and gastrocnemius muscles at the end of the treadmill trial, it is speculated that the lesser disturbance in acid-base balance seen in endurance performers may have been due to a lesser production of metabolites in their running musculature when compared to nonendurance performers.
x. Effects of pH on maximal power output and fatigue during short-term dynamic exercise
Six healthy subjects performed four exercise studies in random order on separate days: a control study, metabolic acidosis induced by ammonium chloride, metabolic alkalosis induced by sodium bicarbonate, and respiratory acidosis induced by 5% CO2 inhalation. The subjects exerted maximal force on the pedals of a constant-velocity cycle ergometer at 100 rpm for 30 s; torque was measured and power calculated. Arterialized venous blood was sampled, and plasma lactate concentrations was measured immediately after and at 2-min intervals for 10 min following exercise. Although maximal peak power and total work, for the 30-s test, were lower in the two acidosis conditions, this effect was not statistically significant. Plasma lactate 30-s postexercise was lower in metabolic acidosis (2.8 +/- 1.6 mmol X 1(-1) (mean +/- SD) and respiratory acidosis (1.5 +/- 0.8 mmol X 1(-1) than in placebo conditions (5.9 +/- 3.3 mmol X 1(-1) and metabolic alkalosis 7.8 +/- 4.2 mmol X 1(-1). These differences were maintained but lessened during 10 min of recovery. In contrast to previous studies, which showed a marked reduction in endurance time during sustained heavy exercise, reductions in blood pH are associated with only small reductions in the total work performed in 30 s of maximal exercise. A delayed and smaller accumulation of lactate in plasma was observed following exercise during acidosis.
x. Relationship between reaction time, sprintrace result and age for male sprinters at 2004 Olimpic Games in Athens
Introduction There are not many available research studies dealing with the characteristics of reaction time, or its influence on sprint race performance (Slater-Hammel & Stumpner, 1952 ; Fairclough, 1952 ; Ozolin, 1986 ; Brueggemann & Glad, 1988 ; Mero & Komi, 1990 ; Martin & Buonchristiani, 1995 ; Collet, 2000). Most of them were not able to establish the correlation between the reaction time and the result in sprint. Therefore, the purpose of this research is to examine the relationship between the age of the sprinters and their reaction time as well as between reaction time and the sprint result in every sprint event for male sprinters who performed at the 2004 Olympic Games in Athens. Methods The sample of entities consists of all male athletes (sprinters and decathlon athletes, N=357) who performed at the 2004 Olympic Games in Athens. The recorded values of the attained result at the competition (R), values of reaction time (RT) and values of the age (YRS) of the sprinters accomplished at higher competitive level were taken for the analyses of this research study. The sample of variables is presented by 8 sprint events (100 m flat, 110 m hurdles (110 m H), 200 m flat, 400 m flat, 400 m hurdles (400 m H), 100 m as a decathlon event (100 m D), 110 m hurdles as a decathlon event (110 m H D) and 400 m as a decathlon event (400 m D). All data collected were analyzed by program package Statistica for Windows version 7 ; consequently, general univariate analysis of variance (ANOVA) was used to determine the differences between the arithmetic means of 8 sprint events in the variable reaction time as well as to determine the differences between competitive levels within every sprint event in the variable reaction time. Correlation analysis between reaction time and race result and reaction time and age of sprinters was calculated. Results The results showed existence of statistically significant differences in average reaction time values between longer and shorter sprint events but however, there were no statistically significant differences in reaction time between different competitive levels within analyzed sprint events, except of sprint event 100 m flat. Correlation analysees yielded results that there was a tendency that older sprinters reacted faster at start while statistically significant (positive) correlation between reaction time and sprint result was found for the sprint events 100 m flat and 110 m hurdles. Discussion It can be said that reaction time has significant influence on sprint result but only in short sprint events. When it comes to reaction time, it is interesting how top-level sprinters do not show significantly better values of reaction time than sprinters who managed to perform in qualification and semifinals rounds. It was found that older sprinters tend to react faster at the start. That means that in training preparation with younger sprinters more attention should be devoted to psychological preparation.
x. Supervision of body composition and cardiovascular parameters in long sprint running athletes (400 m)
INTRODUCTION: The follow-up of performances and the prevention about possible incidents at the athletes make necessary the medical supervision in physical training.The aims of this study are to estimate the effect of a precompetition training program in athletes' body composition, and cardiovascular modifications (in clinical examination and electrocardiogram) MATERIALS ET METHODS: Ten athletes (3 men and 7 women; mean age of 23.6 +/- 3.16 years) of Dakar international Athletics' Center are subjected to a training on a period of 2 months in aerobic dominant followed by a period of 3 months in anaerobic dominant. At the beginning and the end of training program, an electrocardiogram is recorded after blood pressure (BP) measure in lying and standing posture and heart rate (HR) take. The weight, height and cutaneous folds are measured to calculate the body fat percentage, fat body mass, fat-free mass and body mass index. Every athlete has performed the Ruffier test Comparisons are realized by the paired t-test, statistically significant for a p value < 0,05 RESULTS: Significant declines after training interest HR (79.2 +/- 14.7 vs 63.2 +/- 10.25 beat min(-1); p< 0.001), systolic BP in standing posture (11.8 +/- 0.44 vs 10.6 +/- 0.96 mmHg; p= 0.02), and Ruffier index (4.4 +/- 3.28 vs 2.23 +/- 1.62; p= 0.048) whereas the fat-free mass increased (53.14 +/- 8.41 vs 54.16 +/- 9.67 kg; p= 0.046). At the electrocardiogram, the number of athletes having sinusal bradycardia is crossed from 1 to 4; there is no modification as for the two cases of uncomplete right bundle-branch block and the pre-existent left ventricular hypertrophy. Negative T waves in V1 and V2 leads are present in one athlete before training and in two others after. CONCLUSION: The impact of the specific training on body is real, interesting more the cardiovascular system.
x. Laboratory and Field Tests in Evaluation of Anaerobic Fitness in Elite Hurdlers
Sport results in hurdling (110m HH and 400m IH) are determined by
movement coordination (technical skills) and work capacity. The most
important mechanisms incorporated in hurdling include anaerobic power
and anaerobic capacity, which are manifested in speed and strength exer-
cises.
The main objective of this paper was to determine the relationships be-
tween results of laboratory and field anaerobic tests with sport specific
results in hurdle racing. Additionally, an alternative application of these
tests in the evaluation of fitness of hurdlers was considered.
The research material included 45 Polish elite hurdlers over 110m
(n=21) and 400m (n=24). All considered athletes were of national and
international level, including European and World Championship final-
ists.
During three different stages of the annual training cycle all athletes
completed the 30s Wingate test and 4 anaerobic field tests which included
the 30m sprint, standing triple jump, overhead shot throw and a 150 or
500m run.
The differences in results obtained in particular phases of the training cy-
cle were analyzed with the use of ANOVA, while those results between
high and intermediate hurdlers were analyzed with the Students “t” test.
The relationships between sport results and values of anaerobic tests
were determined with the application of Pearson’s linear correlations.
The research showed no differences in results of the Wingate test con-
ducted in particular stages of the annual macrocycle. Significant differ-
ences were observed in the results of field tests, especially those evaluat-
ing explosive strength of lower limbs and specific speed endurance
x. Influence of Diuretic-Induced Dehydration on Competitive Sprint and Power Performance.
Diuretic-induced dehydration impairs prolonged running performance (> 1500 m). Sprinting performance may suffer by similar mechanisms (i.e., altered cardiovascular strain, heat storage, and metabolism) or may improve because of reduced mass to accelerate and carry.
Purpose: To examine sprint and power performance after diuretic-induced dehydration.
Methods: After six sprint practice sessions, nine male former sprinters (mean +/- SD; age, 21 +/- 2 yr; body mass (BM), 80.0 +/- 5.2 kg; height, 1.78 +/- 0.08 m; body fat, 14 +/- 4%) participated in a 50-m race, a 200-m race, a 400-m race, and a vertical jump on an indoor synthetic track, once when dehydrated (40-mg furosemide; DD) and once with no diuretic (CON) using a counter-balanced crossover design. Plasma volume change (%[delta]PV), heart rate (HR), blood pressure, rectal temperature, serum electrolytes, plasma lactate, plasma glucose, rating of perceived exertion, thirst, and thermal sensations were measured before and after each race.
Results: Sprint times (DD vs CON) for the 50 m (6.72 +/- 0.28 vs 6.73 +/- 0.29 s), 200 m (25.95 +/- 1.20 vs 26.21 +/- 1.42 s), and 400 m (59.01 +/- 4.26 vs 58.68 +/- 3.68 s) were similar for both conditions, as was vertical jump height (0.67 +/- 0.10 vs 0.66 +/- 0.11 m). This occurred despite losing 2.2 +/- 0.4% BM and 7.3 +/- 6.7%[delta]PV (50/200 m) or 2.5 +/- 0.4% BM and 7.1 +/- 2.7% [delta]PV (VJ/400 m) in response to DD.
Conclusions: Diuretic-induced dehydration was not detrimental to sprint and power performance. Metabolic, thermoregulatory, and cardiovascular variables were not significantly altered by DD. Furthermore, the theoretical benefit of dehydration on performance (i.e., BM reduction) was not supported in this subject cohort.
x. The effects of wind and altitude in the 400-m sprint
In this paper I use a mathematical model to simulate the effect of wind and altitude on men's and women's 400-m race performances. Both wind speed and direction were altered to calculate the effect on the velocity profile and the final time of the sprinter. The simulation shows that for a constant wind velocity, changing the wind direction can produce a large variation in the race time and velocity profile. A wind of velocity 2 m?·?s-1 is generally a disadvantage to the 400-m runner but this is not so for all wind directions. Constant winds blowing from some directions can provide favourable conditions for the one-lap runner. Differences between the running lanes can be reduced or exaggerated depending on the wind direction. For example, a wind blowing behind the runner in the back straight increases the advantage of lane 8 over lane 1. Wind conditions can change the velocity profile and in some circumstances produce a maximum velocity much later than is evident in windless conditions. Lower air density at altitude produces a time advantage of around 0.06 s for men (0.07 s for women) for each 500-m increase in elevation.
x. Effects of beta-alanine supplementation on exercise performance during a competitive wrestling season: an 8-week open label pilot study
The goal of wrestlers during a competitive season is to maintain or lose body weight without compromising athletic performance. However, some studies have reported decrements in exercise performance associated with weight loss and/or the strain of a competitive season. The purpose of this study, therefore, was to examine the effects of 8 week beta-alanine (?-ala) supplementation on exercise performance in Division II collegiate wrestlers during a competitive season.
Methods
25 college wrestlers (age 18 to 22 y) volunteered to participate in this study, and 18 subjects (mean BMI 24.7 ± 3.7) completed the study. Each participant ingested 4 g/d of ?-ala in an open-label manner during the final eight weeks of their competitive season. The subjects followed a standard training protocol for collegiate wrestling as dictated by the head coach. They were also required to maintain uniform body mass during the entire eight weeks, as per weight bracket allowance during the competitive season. Before and after supplementation, subjects performed a 400 m sprint and 90 degree flexed-arm hang to exhaustion. Immediately prior to and following the pre treatment and post treatment 400 m sprint, subjects blood lactate was taken via finger stick and analyzed to determine lactate increase during the 400 m sprint.
Results
The subjects showed significant decrease (p < 0.01) in 400 m sprint time (-3.5 s ± 2.4 s, mean ± SD) and significant increase (p < 0.01) in 90 degree flexed-arm hang (+ 8.5 s ± 8.35 s, mean ± SD). No significant changes (p > 0.05) in blood lactate values were observed.
Conclusion
The results of our study suggest that supplementation of ?-ala may improve exercise performance in wrestlers during a competitive season. Because of the design of this experiment, it is impossible to identify exactly how much of the positive effects experienced by the subjects was a direct result of the supplementation. However, due to the large increase in performance and the similarity of results in comparison to other ?-ala studies, we feel our study suggests efficacy of ?-ala supplementation. The ergogenic effects of ?-ala supplementation during a competitive wrestling season needs to be confirmed in placebo-controlled trials.
x. PRONOUNCED MUSCLE DEOXYGENATION DURING SUPRAMAXIMAL EXERCISE UNDER SIMULATED HYPOXIA IN SPRINT ATHLETES
The purpose of this study was to determine whether acute hypoxia alters the deoxygenation level in vastus lateralis muscle during a 30 s Wingate test, and to compare the muscle deoxygenation level between sprint athletes and untrained men. Nine male track sprinters (athletic group, VO2max 62.5 ± 4.1 ml/kg/min) and 9 healthy untrained men (untrained group, VO2max 49.9 ± 5.2 ml·kg-1·min-1) performed a 30 s Wingate test under simulated hypoxic (FIO2 = 0.164 and PIO2 = 114 mmHg) and normoxic conditions. During the exercise, changes in oxygenated hemoglobin (OxyHb) in the vastus lateralis were measured using near infrared continuous wave spectroscopy. Decline in OxyHb, that is muscle deoxygenation, was expressed as percent change from baseline. Percutaneous arterial oxygen saturation (SpO2), oxygen uptake (VO2), and ventilation (VE) were measured continuously. In both groups, there was significantly greater muscle deoxygenation, lower SpO2, lower peakVO2, and higher peakVE during supramaximal exercise under hypoxia than under normoxia, but no differences in peak and mean power output during the exercise. Under hypoxia, the athletic group experienced significantly greater muscle deoxygenation, lower SpO2, greater decrement in peakVO2 and increment in peakVE during the exercise than the untrained group. When the athletic and untrained groups were pooled, the increment of muscle deoxygenation was strongly correlated with lowest SpO2 in the 30 s Wingate test under hypoxia. These results suggest that acute exposure to hypoxia causes a greater degree of peripheral muscle deoxygenation during supramaximal exercise, especially in sprint athletes, and this physiological response would be explained mainly by lower arterial oxygen saturation.
x. Comparison of maximal anaerobic running tests on a treadmill and track
To develop a track version of the maximal anaerobic running test, 10 sprint runners and 12 distance runners performed the test on a treadmill and on a track. The treadmill test consisted of incremental 20-s runs with a 100-s recovery between the runs. On the track, 20-s runs were replaced by 150-m runs. To determine the blood lactate versus running velocity curve, fingertip blood samples were taken for analysis of blood lactate concentration at rest and after each run. For both the treadmill and track protocols, maximal running velocity (vmax), the velocities associated with blood lactate concentrations of 10 mmol · l-1 (v10 mM) and 5 mmol · l-1 (v5 mM), and the peak blood lactate concentration were determined. The results of both protocols were compared with the seasonal best 400-m runs for the sprint runners and seasonal best 1000-m time-trials for the distance runners. Maximal running velocity was significantly higher on the track (7.57 ± 0.79 m · s-1) than on the treadmill (7.13 ± 0.75 m · s-1), and sprint runners had significantly higher vmax, v10 mM, and peak blood lactate concentration than distance runners (P<0.05). The Pearson product - moment correlation coefficients between the variables for the track and treadmill protocols were 0.96 (vmax), 0.82 (v10 mM), 0.70 (v5 mM), and 0.78 (peak blood lactate concentration) (P<0.05). In sprint runners, the velocity of the seasonal best 400-m run correlated positively with vmax in the treadmill (r = 0.90, P<0.001) and track protocols (r = 0.92, P<0.001). In distance runners, a positive correlation was observed between the velocity of the 1000-m time-trial and vmax in the treadmill (r = 0.70, P<0.01) and track protocols (r = 0.63, P<0.05). It is apparent that the results from the track protocol are related to, and in agreement with, the results of the treadmill protocol. In conclusion, the track version of the maximal anaerobic running test is a valid means of measuring different determinants of sprint running performance.
x. Program Design Based on a Mathematical Model Using Rating of Perceived Exertion for an Elite Japanese Sprinter: A Case Study
We investigated the effects of program design on 400-m sprint time by applying a Rating of Perceived Exertion (RPE) mathematical model to training performance. The subject was 24 years old and had been training for 9 years. His best performance in 400-m sprint competitions was 45.50 seconds. Body weight, resting heart rate, training time and RPE were monitored daily after training sessions. Similarly, performance in 400-m races was recorded 9 times during 2003. At the World Championships in Athletics in France, the subject's team placed eighth in the 1,600-m relay. The RPE mathematical model was able to predict changes in performance. Rate of matching was statistically significant (r2 = 0.83, F ratio = 34.27, p < 0.001). Application of the RPE mathematical model to the design of a training program specific to the needs of a 400-m sprinter indicates a potentially powerful tool that can be applied to accurately assess the effects of training on athletic performance.
x. Elite Long Sprint Running: A Comparison between Incline and Level Training Sessions.
Purpose: We compared incline and level training sessions as usually used in elite 400-m runners through stride kinematics and muscular activity measurements.
Methods: Nine highly trained 400-m runners (international and French national level) performed two maximal velocity sprints: 1) 300-m on level ground (LEV) and 2) 250-m on an incline ground (INC) characterized by a mean +/- SD grade of 5.4 +/- 0.7%. Kinematics (250 Hz) and electromyography parameters (root mean square [RMS] and integrated electromyography [iEMG] measurements) were analyzed (from 40- to 50-m phases).
Results: INC induced a decrease in running velocity compared to LEV (6.28 +/- 0.38 vs 7.56 +/- 0.38 m[middle dot]s-1) explained by a reduction in stride length (-14.2%) and stride rate (-7.4%) and by an increase in push-off time (+26.4%). Kinematics analysis indicated that the lower limbs were more flexed during INC running. Concerning the level of activity of the lower limb muscles, the major findings pointed out the decrease in RMS for semitendinosus and biceps femoris muscles during the contact phase and for vastus lateralis during its concentric phase. However, iEMG of both semitendinosus and biceps femoris muscles remained constant during both contact and push-off phases.
Conclusion: Our results are clearly different from those of previous studies carried out at similar absolute velocities in both LEV and INC conditions, which were not the case in this study. The lower running velocity marking INC running was associated with a decrease in the activation of the hamstrings. Trainers should particularly consider this lower level of activation of the hamstrings muscles during INC maximal sprint.
x. Relative functional buffering capacity in 400-meter runners, long-distance runners and untrained individuals
Abstract Buffering is a factor which influences performance in short and middle-term endurance by compensating exercise acidosis. The aim of the study was to establish whether respiration parameters are a relative measure of buffering capacity and to study the influence of buffering on specific performance parameters. Three groups (each of ten subjects) with defined degrees of adaptation [untrained (UT), aerobic-trained (AeT) and elite 400-m runners (AnT) with a best time of 48.47 ± 0.98 s] were examined in an incremental multi-stage test on the treadmill. Breath-by-breath gas analysis was performed using mass spectrometry and computer routines. Serum lactate concentrations were determined at each exercise level until subjective exhaustion. A value for the relative functional buffering capacity (re1FB) was calculated using exercise metabolic parameters. Running speed at the lactate threshold was used as the starting point of buffering. The start of respiratory compensation of acidosis (RCP) was taken as the endpoint of buffering. RCP was determined at the point of decrease in end-tidal CO2 content (CO2-ET). Re1FB was given in percent of buffering to running speed at RCP. Group AnT attained the same maximum performance data (maximum running speed, maximum rate of O2 consumption) as group AeT. However, these values were attained in group AnT with a significantly higher re1FB (AnT: 31.0±3.2% vs. AeT: 15.7±3.9%,P < 0.0001), while a higher lactate threshold indicated a greater oxidative capacity in AeT (AeT: 3.07±0.26 m · s–1 vs. AnT: 2.68±0.22 m · s–1). It is concluded that the combination of ventilatory parameters and determining the LT seems to be a useful measure for the total amount of buffering during high-intensity exercise. The higher content of buffer-active proteins in sprinters' muscles may be considered the main cause of their higher re1FB.
x. Peak oxygen deficit predicts sprint and middle-distance track performance
The purpose of this study was to determine the value of the peak oxygen deficit (POD) as a predictor of sprint and middle-distance track performance. POD, peak blood laclate, [latin capital V with dot above]O2peak, lactate threshold, and running economy at 3.6 m[middle dot]s-1 were measured during horizontal treadmill running in 22 male and 19 female competitive runners of different event specialties. Subjects also completed running performance trials at 100, 200, 400, 800, 1500, and 5000 m. Correlations of track performances with POD (ml[middle dot]kg-1) (-0.66, -0.71, -0.71, -0.62, -0.52, and -0.40) were moderately strong at the sprint and middle distances, accounting for 44-50% of the performance variance at the three shortest distances. Correlations of track performances with peak blood lactate concentration were lower than with POD and accounted for approximately one-half as much of the performance variance (21-26%) at the three shortest distances. Multiple regression analyses indicated that the POD was the strongest metabolic predictor of 100-, 200- and 400-m performance, and that [latin capital V with dot above]O2peak was the strongest metabolic predictor of 800-, 1500-, and 5000-m performance. We conclude that the POD is a moderately strong predictor of sprint and middle-distance track performance.
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x. Reliability of peak-lactate, heart rate, and plasma volume following the Wingate test
Purpose: The 30-s Wingate Anaerobic Test (WAnT) has been used to assess anaerobic performance capacity and to evaluate physiological responses to supramaximal exercise. Blood lactate concentration ([La]) following supramaximal exercise is often used in the field and in the laboratory to assess the glycolytic contribution to exercise. Although the reliability of the performance in the WAnT has been established, this has not been the case with the WAnT's [La] response. Thus, the main purpose of this research was to study the test-retest reliability of peak [La] following the WAnT. Additionally, the test-retest reliability of the heart rate (HR) and plasma volume changes (?PV) response was also evaluated.
Methods: Twenty-nine subjects (15 male, 14 female) of diverse training levels as well as physical characteristics(mean ± SD: 23.3 ± 7.0 yr, 62.5 ± 12.0 kg, 170.8 ± 9.7 cm, and 16.3 ± 6.2% fat) performed two WAnTs within 1 wk. Capillary blood was sampled from a prewarmed fingertip at rest, just before the WAnT and at 3, 5, 7, and 9 min following it. HR was also measured during these times.
Results: Mean-power(MP) (±SE) in test 1 and test 2 was 8.4 ± 0.2 and 8.3 ± 0.2 W·kg-1 body mass, respectively. Peak [La] was attained 5-7 min following the WAnTs and was not significantly different between test 1 and test 2 (9.7 ± 0.3 vs 9.8 ± 0.3 mM, respectively). Peak HR occurred within 5 s post-WAnT and was not different between tests (170.8 ± 2.2 and 171.3 ± 2.2 beats·min-1, in test 1 and test 2, respectively). Peak ?PV was not different between tests (-12.0 ± 3.4 and -11.1± 3.2%, in test 1 and test 2, respectively). The intraclass reliability coefficients for peak [La]. peak HR and ?PV were 0.926, 0.941, and 0.878, respectively, whereas the corresponding value for MP was 0.982.
Conclusions: We conclude that peak [La], peak HR, and ?PV following the WAnT are reliable measures.