Performance Area > Peer Reviewed Studies Discussion
Sleep, Biological Rhythms, & Stress - its effect on performance
adarqui:
All conclusions of studies will be listed in this original post (TABLE OF SUMMARIES) for quick reference.
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Post anything related to Sleep, Biological Rhythms, or Stress and its effect on performance.
1A. Elevations in core and muscle temperature impairs repeated sprint performance
--- Quote ---Conclusion: Although an elevated muscle temperature is expected to promote sprint performance, power output during the repeated sprints was reduced by hyperthermia. The impaired performance does not seem to relate to the accumulation of recognized metabolic fatigue agents and we, therefore, suggest that it may relate to the influence of high core temperature on the function of the central nervous system.
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1. Electro-mechanical response times and muscle strength after sleep deprivation.
--- Quote ---The results suggest that subjects who have undergone 60 h of SD can react as fast, and with as much force, as those who have had 7 h of sleep per night.
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2. Physical performance and physiological responses following 60 hours of sleep deprivation.
--- Quote ---These results suggest that sleep loss of up to 60 h will not impair the capability for physical work, a finding of considerable importance in sustained military operations which frequently involve the combination of both physical and mental tasks.
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3. The effect of partial sleep deprivation on weight-lifting performance
--- Quote ---Results indicate that submaximal lifting tasks are more affected by sleep loss than are maximal efforts, particularly for the first two nights of successive sleep restriction.
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4. Effects of caffeine, sleep loss, and stress on cognitive performance and mood during U.S. Navy SEAL training
--- Quote ---Sleep deprivation and environmental stress adversely affected performance and mood. Caffeine, in a dose-dependent manner, mitigated many adverse effects of exposure to multiple stressors. Caffeine (200 and 300 mg) significantly improved visual vigilance, choice reaction time, repeated acquisition, self-reported fatigue and sleepiness with the greatest effects on tests of vigilance, reaction time, and alertness. Marksmanship, a task that requires fine motor coordination and steadiness, was not affected by caffeine. The greatest effects of caffeine were present 1 h post-administration, but significant effects persisted for 8 h.
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5. Caffeine effects on marksmanship during high-stress military training with 72 hour sleep deprivation.
--- Quote ---Sighting time was significantly faster in sleep deprived individuals after taking 200 or 300 mg of caffeine compared with placebo or 100 mg of caffeine. No differences in accuracy measures between caffeine treatment groups were evident at any test period. CONCLUSION: During periods of sleep deprivation combined with other stressors, the use of 200 or 300 mg of caffeine enabled SEAL trainees to sight the target and pull the trigger faster without compromising shooting accuracy.
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6. Sleep-dependent learning: a nap is as good as a night
--- Quote ---Thus, from the perspective of behavioral improvement, a nap is as good as a night of sleep for learning on this perceptual task.
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7. The effects of two alternative timings of a one-hour nap on early morning performance.
--- Quote ---It was concluded that a one-hour nap could counteract the late night performance decrement.
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8. Effects of Exercise, Bedrest and Napping on Performance Decrement During 40 Hours
--- Quote --- ... and naps reduce or remove this impairment. Bedrest is not a substitute for sleep.
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9. Impact of Ramadan on physical performance in professional soccer players
--- Quote ---Performance declined significantly (p<0.05) for speed, agility, dribbling speed and endurance, and most stayed low after the conclusion of Ramadan. Nearly 70% of the players thought that their training and performance were adversely affected during the fast.
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10. Physical performance responses during 72 h of military operational stress.
--- Quote ---Results: Fat-free mass (-2.3%) and fat mass (-7.3%) declined (P <= 0.05) during SUSOPS. Squat-jump mean power (-9%) and total work (-15%) declined (P <= 0.05) during SUSOPS. Bench-press power output, grenade throw, and marksmanship for pop-up targets were not affected. Obstacle course and box-lift performances were lower (P <= 0.05) on D3 but showed some recovery on D4. Wall building was ~25% lower (P <= 0.05) during SUSOPS.
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11. Circadian variation in sports performance.
Atkinson G, Reilly T.
Centre for Sport and Exercise Sciences, School of Human Sciences, Liverpool John Moores University, England.
--- Quote ---Chronobiology is the science concerned with investigations of time-dependent changes in physiological variables. Circadian rhythms refer to variations that recur every 24 hours. Many physiological circadian rhythms at rest are endogenously controlled, and persist when an individual is isolated from environmental fluctuations. Unlike physiological variables, human performance cannot be monitored continuously in order to describe circadian rhythmicity. Experimental studies of the effect of circadian rhythms on performance need to be carefully designed in order to control for serial fatigue effects and to minimise disturbances in sleep. The detection of rhythmicity in performance variables is also highly influenced by the degree of test-retest repeatability of the measuring equipment. The majority of components of sports performance, e.g. flexibility, muscle strength, short term high power output, vary with time of day in a sinusoidal manner and peak in the early evening close to the daily maximum in body temperature. Psychological tests of short term memory, heart rate-based tests of physical fitness, and prolonged submaximal exercise performance carried out in hot conditions show peak times in the morning. Heart rate-based tests of work capacity appear to peak in the morning because the heart rate responses to exercise are minimal at this time of day. Post-lunch declines are evident with performance variables such as muscle strength, especially if measured frequently enough and sequentially within a 24-hour period to cause fatigue in individuals. More research work is needed to ascertain whether performance in tasks demanding fine motor control varies with time of day. Metabolic and respiratory rhythms are flattened when exercise becomes strenuous whilst the body temperature rhythm persists during maximal exercise. Higher work-rates are selected spontaneously in the early evening. At present, it is not known whether time of day influences the responses of a set training regimen (one in which the training stimulus does not vary with time of day) for endurance, strength, or the learning of motor skills. The normal circadian rhythms can be desynchronised following a flight across several time zones or a transfer to nocturnal work shifts. Although athletes show all the symptoms of 'jet lag' (increased fatigue, disturbed sleep and circadian rhythms), more research work is needed to identify the effects of transmeridian travel on the actual performances of elite sports competitors. Such investigations would need to be chronobiological, i.e. monitor performance at several times on several post-flight days, and take into account direction of travel, time of day of competition and the various performance components involved in a particular sport. Shiftwork interferes with participation in competitive sport, although there may be greater opportunities for shiftworkers to train in the hours of daylight for individual sports such as cycling and swimming. Studies should be conducted to ascertain whether shiftwork-mediated rhythm disturbances affect sports performance. Individual differences in performance rhythms are small but significant. Circadian rhythms are larger in amplitude in physically fit individuals than sedentary individuals. Athletes over 50 years of age tend to be higher in 'morningness', habitually scheduling relatively more training in the morning and selecting relatively higher work-rates during exercise compared with young athletes. These differences should be recognised by practitioners concerned with organising the habitual regimens of athletes.
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12. Circadian rhythms in two types of anaerobic cycle leg exercise: force-velocity and 30-s Wingate tests.
Souissi N, Gauthier A, Sesboüé B, Larue J, Davenne D.
--- Quote ---The results indicated that oral temperature, P (peak), P (mean) and P (max) varied concomitantly during the day. These results suggest that there was a circadian rhythm in anaerobic performance during cycle tests. The recording of oral temperature allows one to estimate the time of occurrence of maximal and minimal values in the circadian rhythm of anaerobic performance.
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13. Sports, Sleep, and Circadian Rhythms : Circadian Rhythms and Enhanced Athletic Performance in the National Football League
--- Quote ---Circadian rhythms produce daily changes in critical elements of athletic performance. We explored the significance of performing at different circadian times in the national football league (NFL) over the last 25 seasons. West coast (WC) nfl teams should have a circadian advantage over east coast (EC) teams during monday night football (MNF) games because WC teams are essentially playing closer to the proposed peak athletic performance time of day. Retrospectice data analysis was applied to all games involving WC versus EC teams playing on MNF with start times of 9:00 pm Eastern Standard Time (EST) from 1970-1994 seasons. Logistic regression analysis of win-loss records relative to point spreads and home-field advantage were examined. West Coast Teams win more often (p < 0.01) and by more points per game than EC teams. West Coast teams are performing significantly (p < 0.01) better than is predicted by the Las Vegas odds (the point spread). This apparent advantage enhances home-field advantage for WC teams and essentially eliminates the beneficial effects of home-field advantage for EC teams during MNF games. These results support the presence of an enhancement of athletic performance at certain circadian times of the day.
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14. Diurnal Rhythm of the Muscular Performance of Elbow Flexors During Isometric Contractions
--- Quote ---We also assessed variations in the level of maximal activity of the muscle under maximal voluntary contraction. Neuromuscular efficiency fluctuated during the day, with maximal and minimal efficiency at 18:00 h and 9:00 h, respectively, whereas activation level was maximal at 18:00 h and minimal at 9:00 h. The diurnal rhythm of torque was accounted for by variations in both central nervous system command and the contractile state of the muscle.
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15. Circadian performance differences between morning and evening 'types'
--- Quote ---significant differences were apparent with the number of items correctly rejected. M (MORNING) types' correct rejection levels were significantly better than E (EVENING) types' in the morning, whereas they were worse during the evening. Whilst E types showed a steady improvement throughout the day, M types showed a general decline. A post-lunch dip in performance was quite evident for M types, but not for E types. In addition, the circadian trends in correct rejection levels and body temperature were highly positively correlated for E types, but a significant negative relationship between these parameters was found for M types. These findings are discussed.
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16. CIRCADIAN RHYTHMS IN HUMAN MUSCULAR EFFICIENCY: CONTINUOUS PHYSICAL EXERCISE VERSUS CONTINUOUS REST. A CROSSOVER STUDY
--- Quote ---Despite the standardized conditions, the results showed that isometric maximal strength varied with time of day during both a submaximal exercise and at rest without prior exercise. The sine waves representing these two rhythms were correlated significantly. Although at rest the diurnal rhythm followed muscular activity (i.e., neurophysiological factors), during exercise, this rhythm was thought to stem more from fluctuations in the contractile state of muscle. (Chronobiology International, 17(5), 693-704, 2000)
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17. Circadian rhythms have no effect on cycling performance
--- Quote ---Resting oral temperature was the only variable to show a significant time of day effect (p<0.05). Oral temperature during the afternoon was higher than both morning and evening results by 0.76°C and 0.09°C respectively. Although athletic performance may be enhanced by training programs that are compatible with an individuals body clock, the ability to perform and train at various times has an adaptive response which appears to over-ride these naturally inherent rhythms.
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18. Time-of-day dependence of isokinetic leg strength and associated interday variability.
--- Quote ---This finding appears to be consistent with current knowledge about time-of-day effects on the assessment of muscular strength. Thus for stable and maximal values to be obtained during isokinetic leg testing, the use of multiple-trial protocols is recommended, with testing occurring as close to 18.00-19.30 hours as possible. In addition, the observed significant time-of-day effect suggests that appropriate comparison of maximal isokinetic leg strength can only be achieved based on data obtained within 30 min of the same time of day.
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19. Effects of dehydration on isometric muscular strength and endurance.
--- Quote ---These results provide evidence that isometric strength and endurance are unaffected 3.5 h after dehydration of approximately 4% body mass.
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20. Sleep deprivation induced anxiety and anaerobic performance
--- Quote ---Neither anaerobic pa-
rameters nor state anxiety levels were affected by one night
partial sleep deprivation. Our results suggest that 30 hours con-
tinuous wakefulness may increase anxiety level without impair-
ing anaerobic performance, whereas one night of partial sleep
deprivation was ineffective on both state anxiety and anaerobic
performance.
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21. The role of a short post-lunch nap in improving cognitive, motor, and sprint performance in participants with partial sleep deprivation
--- Quote ---These results indicate that a post-lunch nap improves alertness and aspects of mental and physical performance following partial sleep loss, and have implications for athletes with restricted sleep during training or before competition.
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22. Effects of One Night of Partial Sleep Deprivation upon Diurnal Rhythms of Accuracy and Consistency in Throwing Darts
--- Quote ---Increasing time awake was associated with decreased alertness and increased fatigue, as well as slight negative effects upon performance. We conclude that the simple task of throwing darts at a target provides information about chronobiological changes in circumstances where time awake and sleep loss might affect psychomotor performance.
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23. Effects of a selective sleep deprivation on subsequent anaerobic performance
--- Quote ---The peak power, the mean power output and the peak velocity recorded after partial sleep deprivation were not modified in comparison with the values obtained after the reference night. These findings suggest that acute sleep loss did not contribute to alterations in supramaximal exercise.
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24. Effects of one night's sleep deprivation on anaerobic performance the following day
--- Quote ---Up to 24 h of waking, anaerobic power variables were not affected; however, they were impaired after 36 h without sleep. Analysis of variance revealed that blood lactate concentrations were unaffected by sleep loss, by time of day of testing or by the interaction of the two. In conclusion, sleep deprivation reduced the difference between morning and afternoon in anaerobic power variables. Anaerobic performances were unaffected after 24 h of wakefulness but were impaired after 36 h without sleep.
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25. Sleep deprivation and exercise
--- Quote ---Concerning anaerobic power and strength, significant alterations have not been found; however, for prolonged events there may be an interaction between these two factors, which suggests a protection mechanism. Nevertheless, it is important to consider that one of the main alterations caused by sleep deprivation the increase of the subjective perception, which presents a factor to decrease and compromise the physical performance per se, and may represent a masking element of the deleterious effects of sleep deprivation. Thus, the aim of present review is to discuss the different aspects of relationship between physical exercise and sleep deprivation, showing their effects and consequences in physical performance.
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26. The Impact of Sleep Deprivation on Decision Making: A Review
--- Quote ---Few sleep deprivation (SD) studies involve realism or high-level decision making, factors relevant to managers, military commanders, and so forth, who are undergoing prolonged work during crises. Instead, research has favored simple tasks sensitive to SD mostly because of their dull monotony. In contrast, complex -based, convergent, and logical tasks are unaffected by short-term SD, seemingly because of heightened participant interest and compensatory effort. However, recent findings show that despite this effort, SD still impairs decision making involving the unexpected, innovation, revising plans, competing distraction, and effective communication. Decision-making models developed outside SD provide useful perspectives on these latter effects, as does a neuropsychological explanation of sleep function. SD presents particular difficulties for sleep-deprived decision makers who require these latter skills during emergency situations.
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27. The Acute Effects of Twenty-Four Hours of Sleep Loss on the Performance of National-Caliber Male Collegiate Weightlifters
--- Quote ---Currently, the degree to which sleep loss influences weightlifting performance is unknown. This study compared the effects of 24 hours of sleep loss on weightlifting performance and subjective ratings of psychological states pre-exercise and postexercise in national-caliber male collegiate weightlifters. Nine males performed a maximal weightlifting protocol following 24 hours of sleep loss and a night of normal sleep. The subjects participated in a randomized, counterbalanced design with each sleep condition separated by 7 days. Testosterone and cortisol levels were quantified prior to, immediately after, and 1 hour after the resistance training session. Additionally, profile of mood states and subjective sleepiness were evaluated at the same time points. The resistance training protocol consisted of several sets of snatches, clean and jerks, and front squats. Performance was evaluated as individual exercise volume load, training intensity and overall workout volume load, and training intensity. During each training session the maximum weight lifted for the snatch, clean and jerk, and front squat were noted. No significant differences were found for any of the performance variables. A significant decrease following the sleep condition was noted for cortisol concentration immediately after and 1 hour postexercise. Vigor, fatigue, confusion, total mood disturbance, and sleepiness were all significantly altered by sleep loss. These data suggest that 24 hours of sleep loss has no adverse effects on weightlifting performance. If an athlete is in an acute period of sleep loss, as noticed by negative mood disturbances, it may be more beneficial to focus on the psychological (motivation) rather than the physiological aspect of the sport.
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28. Effect of sleep deprivation on tolerance of prolonged exercise
--- Quote ---These findings suggest that the psychological effects of acute sleep loss may contribute to decreased tolerance of prolonged heavy exercise.
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29. Sleep deprivation and cardiorespiratory function
--- Quote ---Physiological responses to sub-maximal exercise showed persistence of the normal diurnal rhythm in heart rate and oxygen consumption, with no added effects due to sleep deprivation. However, ratings of perceived exertion (Borg scale) increased significantly throughout sleep deprivation. The findings are consistent with a mild respiratory acidosis, secondary to reduced cortical arousal and/or a progressive depletion of tissue glycogen stores which are not altered appreciably by moderate physical activity.
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30. Caffeine Use in Sports: Considerations for the Athlete.
--- Quote ---caffeine can be taken gradually at low doses to avoid tolerance during the course of 3 or 4 days, just before intense training to sustain exercise intensity; and caffeine can improve cognitive aspects of performance, such as concentration, when an athlete has not slept well. Athletes and coaches also must consider how a person's body size, age, gender, previous use, level of tolerance, and the dose itself all influence the ergogenic effects of caffeine on sports performance.
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31. Effects of Caffeine on Prolonged Intermittent-Sprint Ability in Team-Sport Athletes.
--- Quote ---Conclusion: This study revealed that acute caffeine ingestion can significantly enhance performance of prolonged, intermittent-sprint ability in competitive, male, team-sport athletes.
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32. Maximal aerobic exercise following prolonged sleep deprivation.
--- Quote ---The effect of 60 h without sleep upon maximal oxygen intake was examined in 12 young women, using a cycle ergometer protocol. The arousal of the subjects was maintained by requiring the performance of a sequence of cognitive tasks throughout the experimental period. Well-defined oxygen intake plateaus were obtained both before and after sleep deprivation, and no change of maximal oxygen intake was observed immediately following sleep deprivation. The endurance time for exhausting exercise also remained unchanged, as did such markers of aerobic performance as peak exercise ventilation, peak heart rate, peak respiratory gas exchange ratio, and peak blood lactate.
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33. Multiple Effects of Caffeine on Simulated High-Intensity Team-Sport Performance.
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--- Quote ---The effects of caffeine on mean performance (+/-90% confidence limits) over all 14 circuits were: sprint speeds, 0.5% (+/-1.7%) through 2.9% (+/-1.3%); first-drive power, 5.0% (+/-2.5%); second-drive power, -1.2% (+/-6.8%); and passing accuracy, 9.6% (+/-6.1%). The enhancements were mediated partly through a reduction of fatigue that developed throughout the test and partly by enhanced performance for some measures from the first circuit. Caffeine produced a 51% (+/-11%) increase in mean epinephrine concentration; correlations between individual changes in epinephrine concentration and changes in performance were mostly unclear, but there were some strong positive correlations with sprint speeds and a strong negative correlation with passing accuracy. Conclusion: Caffeine is likely to produce substantial enhancement of several aspects of high-intensity team-sport performance.
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adarqui:
Time-course of Changes in Inflammatory and Performance Responses Following a Soccer Game: 2328: Board #108 May 30 3:30 PM - 5:00 PM
[F-23 Free Communication/Poster - Exercise Immunology: MAY 30, 2008 1:00 PM - 6:00 PM: ROOM: Hall B]
Fatouros, Ioannis G.1; Chatzinikolaou, Athanasios1; Ispirlidis, Ioannis1; Jamurtas, Athanasios Z.2; Nikolaidis, Michalis G.3; Michailidis, Ioannis4; Douroudos, Ioannis1; Margonis, Konstantinos1; Taxildaris, Kiriakos1
1Democritus University of Thrace, Department of Physical Education & Sport Science, Komotini, Greece. 2University Of Thessaly, Department Of Physical Education & Sports Sciences, Trikala, Greece. 3Institute of Human Performance and Rehabilitation, Centre for Research and Technology, TRIKALA, Greece. 4Democritus University Of Thrace, Komotini, Greece.
Email: fatouros@otenet.gr
(No relationships reported)
A competitive soccer season includes weekly micro-cycles consisting of training, taper, competition, and recovery. The ability of soccer players to fully recover prior to their next major competition is crucial not only for their performance but for injury prevention as well. Information on the time-course of changes in the acute phase inflammatory response, soreness, pain, and performance after a single soccer game is scarce.
PURPOSE: to study the effects of a single soccer game on indices of performance, muscle damage and inflammation during a 6-day recovery period.
METHODS: Twenty-four elite male soccer players (20.1 ± 0.8 yrs, 1.78 ± 0.08 m, 75.2 ± 6.8 kg) were assigned to either an experimental group (E, n=14, played in a game) or a control group (C, n=10, did not participate in the game). Muscle strength, vertical jumping, speed, DOMS, muscle swelling, leukocyte count, creatine kinase (CK), lactate dehydrogenase (LDH), C-reactive protein (CRP), cortisol, testosterone, cytokines IL-6 and IL-1?, TBARS, protein carbnyls (PC) and uric acid were measured prior to the game and immediately post-game as well as 24, 48, 72, 96, 120, and 144 hours following the game.
RESULTS: VJ decreased (P<0.05) 24-h after the game and returned to pre-game values 72-h following the game. 1RM decreased (P<0.05) after the game, reached its lowest value at 48-h post-game, and returned to pre-game levels 96-h after the game. Sprinting ability declined (P<0.05) post-game, reached its lowest value 48-h post-game, and returned to pregame levels after 120-h. An acute phase inflammatory response consisted of a post-game peak of leukocyte count, cytokines and cortisol, a 24 h peak of CRP, TBARS, and DOMS, a 48 h peak of CK, LDH, and PC, and a 72 h peak of uric acid.
CONCLUSIONS: a single soccer game induces short-term muscle damage and marked but transient inflammatory responses. Anaerobic performance seems to deteriorate for as long as 72 h post-game. The acute phase inflammatory response in soccer appears to follow the same pattern as in other forms of exercise. These results clearly indicate the need of sufficient recovery for elite soccer players following a game.
Maximal aerobic exercise following prolonged sleep deprivation.
The effect of 60 h without sleep upon maximal oxygen intake was examined in 12 young women, using a cycle ergometer protocol. The arousal of the subjects was maintained by requiring the performance of a sequence of cognitive tasks throughout the experimental period. Well-defined oxygen intake plateaus were obtained both before and after sleep deprivation, and no change of maximal oxygen intake was observed immediately following sleep deprivation. The endurance time for exhausting exercise also remained unchanged, as did such markers of aerobic performance as peak exercise ventilation, peak heart rate, peak respiratory gas exchange ratio, and peak blood lactate. However, as in an earlier study of sleep deprivation with male subjects (in which a decrease of treadmill maximal oxygen intake was observed), the formula of Dill and Costill (4) indicated the development of a substantial (11.6%) increase of estimated plasma volume percentage with corresponding decreases in hematocrit and red cell count. Possible factors sustaining maximal oxygen intake under the conditions of the present experiment include (1) maintained arousal of the subjects with no decrease in peak exercise ventilation or the related respiratory work and (2) use of a cycle ergometer rather than a treadmill test with possible concurrent differences in the impact of hematocrit levels and plasma volume expansion upon peak cardiac output and thus oxygen delivery to the working muscles.
Effects of Caffeine on Prolonged Intermittent-Sprint Ability in Team-Sport Athletes.
APPLIED SCIENCES
Medicine & Science in Sports & Exercise. 38(3):578-585, March 2006.
SCHNEIKER, KNUT THOMAS 1; BISHOP, DAVID 1; DAWSON, BRIAN 1; HACKETT, LAURENCE PETER 2
Abstract:
Purpose: Caffeine can be a powerful ergogenic aid for the performance of prolonged, submaximal exercise. Little evidence, however, supports an ergogenic effect of caffeine on intermittent-sprint performance. Hence, this study was conducted to examine the effects of acute caffeine ingestion on prolonged intermittent-sprint performance.
Methods: Using a double-blind, placebo-controlled design, 10 male team-sport athletes (amateur level, [latin capital V with dot above]O2peak 56.5 +/- 8.0 mL[middle dot]kg-1[middle dot]min-1) completed two exercise trials, separated by 7 d, 60 min after ingestion of either 6 mg[middle dot]kg-1 caffeine or placebo. The exercise trial was performed on a front-access cycle ergometer and consisted of 2 x 36-min halves, each composed of 18 x 4-s sprints with 2-min active recovery at 35% [latin capital V with dot above]O2peak between each sprint. Urinary caffeine levels were measured after exercise.
Results: The total amount of sprint work performed during the caffeine trial was 8.5% greater than that performed during the placebo trial in the first half (75,165.4 +/- 3,902.9 vs 69,265.6 +/- 3,719.7 J, P < 0.05), and was 7.6% greater in the second half (73,978.7 +/- 4,092.6 vs 68,783.2 +/- 3,574.4 J, P < 0.05). Similarly, the mean peak power score achieved during sprints in the caffeine trial was 7.0% greater than that achieved during the placebo trial in the first half (1330.9 +/- 68.2 vs 1244.2 +/- 60.7 W, P < 0.05), and was 6.6% greater in the second half (1314.5 +/- 68.4 vs 1233.2 +/- 59.9 W, P < 0.05). Urinary caffeine levels following the caffeine trial ranged from 3.5 to 9.1 [mu]g[middle dot]mL-1 (6.9 +/- 0.6 [mu]g[middle dot]mL-1).
Conclusion: This study revealed that acute caffeine ingestion can significantly enhance performance of prolonged, intermittent-sprint ability in competitive, male, team-sport athletes.
Caffeine Use in Sports: Considerations for the Athlete.
Abstract:
The ergogenic effects of caffeine on athletic performance have been shown in many studies, and its broad range of metabolic, hormonal, and physiologic effects has been recorded, as this review of the literature shows. However, few caffeine studies have been published to include cognitive and physiologic considerations for the athlete. The following practical recommendations consider the global effects of caffeine on the body: Lower doses can be as effective as higher doses during exercise performance without any negative coincidence; after a period of cessation, restarting caffeine intake at a low amount before performance can provide the same ergogenic effects as acute intake; caffeine can be taken gradually at low doses to avoid tolerance during the course of 3 or 4 days, just before intense training to sustain exercise intensity; and caffeine can improve cognitive aspects of performance, such as concentration, when an athlete has not slept well. Athletes and coaches also must consider how a person's body size, age, gender, previous use, level of tolerance, and the dose itself all influence the ergogenic effects of caffeine on sports performance.
Electro-mechanical response times and muscle strength after sleep deprivation.
This study examined the effect of 60 h of sleep deprivation (SD) on electromechanical response times (EMRT), maximal voluntary isometric contraction (MVC), rate of force development (RFD), and times required to reach various percentages of MVC, during a maximal voluntary isometric contraction of both the forearm flexors and leg extensors. Eleven male subjects were either sleep deprived for 60 h (E) or performed similar daily activities and slept 7 h per night (C). Performance variables were evaluated at the same time intervals during both conditions. No significant differences were observed between the E and C conditions for EMRT (pre-motor time, electro-mechanical delay, total reaction time) or muscular performance (MVC, RFD). The results suggest that subjects who have undergone 60 h of SD can react as fast, and with as much force, as those who have had 7 h of sleep per night.
Physical performance and physiological responses following 60 hours of sleep deprivation.
Original Investigations
Medicine & Science in Sports & Exercise. 20(4):374-380, August 1988.
SYMONS, J D; VANHELDER, T; MYLES, W S
Abstract:
SYMONS, J. D., T. VANHELDER, and W. S. MYLES. Physical performance and physiological responses following 60 hours of sleep deprivation. Med. Sci. Sports Exerc, Vol. 20, No. 4, pp. 374-380, 1988. The effect of 60 h of sleep deprivation (SD) upon physical performance and physiological responses to exercise was examined in 11 male subjects. The experiment consisted of two conditions separated by at least 10 d. In the experimental condition (E) subjects remained awake for 60 h and in the control condition (C) the same subjects had 7 h of sleep per night. In both conditions subjects reported to the laboratory on the evening prior to d 1 and slept for 7 h. Physical performance testing was carried out on d 1 and again on d 3 after either two nights of sleep or two nights of SD. Results obtained on d 3 are expressed relative to d 1, the control day. Maximal isometric and isokinetic muscular strength and endurance of selected upper and lower body muscle groups, performance of the Wingate Anaerobic Power Test, simple reaction time, the blood lactate response to cycle exercise at 70% [latin capital V with dot above]O2max, and most of the cardiovascular and respiratory responses to treadmill running at 70% and 80% [latin capital V with dot above]O2max, were not significantly altered as a result of SD. These results suggest that sleep loss of up to 60 h will not impair the capability for physical work, a finding of considerable importance in sustained military operations which frequently involve the combination of both physical and mental tasks.
The effect of partial sleep deprivation on weight-lifting performance
Abstract
This study examined the effects of partial sleep deprivation on submaximal and maximal weight-lifting tasks and on subjective states pre- and post-activity. Eight male subjects (aged 18-24 years) were restricted to a nightly ration of 3 h sleep for 3 successive nights after baseline measures on the first day. A 4 day period where normal sleep was permitted fulfilled a control condition, the normal and sleep-deprived conditions being counterbalanced and separated by 10 days. The weight-lifting tasks consisted of biceps curl, bench press, leg press, and dead lift. For each exercise a submaximal load, corresponding to a fixed value on a category ratio scale of exertion, was determined for 20 repetitions; the maximal lift for that exercise was then obtained. A profile of mood states and subjective sleepiness were determined at each test occasion, tests being conducted in the evening of each day. There was no significant effect of sleep loss on performance of maximal biceps curl (p > 0.05) but a significant effect was noted on maximal bench press, leg press, and dead lift (p < 0.001). Trend analysis indicated decreased performance in submaximal lifts for all the 4 tasks: the deterioration was significant after the second night of sleep loss (p<0.01). Performing the lifts had little influence on sleepiness ratings which increased linearly with successive days of sleep loss. Mood states of confusion, vigour, and fatigue were affected significantly by the sleep deprivation regimen (p < 0.001), but there was no significant effect of sleep loss or anger, tension, and depression (p > 0-05). Results indicate that submaximal lifting tasks are more affected by sleep loss than are maximal efforts, particularly for the first two nights of successive sleep restriction.
adarqui:
Effects of caffeine, sleep loss, and stress on cognitive performance and mood during U.S. Navy SEAL training
Rationale. When humans are acutely exposed to multiple stressors, cognitive performance is substantially degraded. Few practical strategies are available to sustain performance under such conditions.
Objective. This study examined whether moderate doses of caffeine would reduce adverse effects of sleep deprivation and exposure to severe environmental and operational stress on cognitive performance.
Methods. Volunteers were 68 U.S. Navy Sea-Air-Land (SEAL) trainees, randomly assigned to receive either 100, 200, or 300 mg caffeine or placebo in capsule form after 72 h of sleep deprivation and continuous exposure to other stressors. Cognitive tests administered included scanning visual vigilance, four-choice visual reaction time, a matching-to-sample working memory task and a repeated acquisition test of motor learning and memory. Mood state, marksmanship, and saliva caffeine were also assessed. Testing was conducted 1 and 8 h after treatment.
Results. Sleep deprivation and environmental stress adversely affected performance and mood. Caffeine, in a dose-dependent manner, mitigated many adverse effects of exposure to multiple stressors. Caffeine (200 and 300 mg) significantly improved visual vigilance, choice reaction time, repeated acquisition, self-reported fatigue and sleepiness with the greatest effects on tests of vigilance, reaction time, and alertness. Marksmanship, a task that requires fine motor coordination and steadiness, was not affected by caffeine. The greatest effects of caffeine were present 1 h post-administration, but significant effects persisted for 8 h.
Conclusions. Even in the most adverse circumstances, moderate doses of caffeine can improve cognitive function, including vigilance, learning, memory, and mood state. When cognitive performance is critical and must be maintained during exposure to severe stress, administration of caffeine may provide a significant advantage. A dose of 200 mg appears to be optimal under such conditions.
The effects of two alternative timings of a one-hour nap on early morning performance.
The effect on performance and sleepiness of two alternative timings of a one-hour nap (2100h and 0430h, respectively) were compared with a control condition (no nap). Twelve healthy male subjects divided into three groups participated in a partly balanced repeated measurements design. At all three occasions the subjects slept 4 h during the preceding night, worked during the day and were then kept awake (except for naps) in the laboratory from 1700h to 0800h the following morning. Performance was measured through a 10-min single choice visual reaction time task administered at 1900h and 0700h. Sleepiness was measured through self-ratings and sleep latency tests at 2100h and 0600h. The results showed clear positive effects of naps (especially the 0430h nap) on performance. The sleep latency measurements showed similar, but less clear tendencies, while ratings of sleepiness did not differentiate between conditions. It was concluded that a one-hour nap could counteract the late night performance decrement.
Caffeine effects on marksmanship during high-stress military training with 72 hour sleep deprivation.
PURPOSE: Navy SEALs (sea, air, land) are elite special warfare units that conduct unconventional warfare primarily in marine environments. Marksmanship accuracy and sighting time were quantified with 62 male trainees during Navy SEAL Hell Week, which involves the combined stress of sleep loss, operational combat scenarios, and cold-wet environmental conditions. Caffeine was administered to minimize deficits due to sleep deprivation. METHODS: Volunteers dry-fired a disabled rifle equipped with a laser-based marksmanship simulator system to measure shooting speed and accuracy. The target was a 2.3-cm diameter circle at a distance of 5 m, simulating a 46 cm target at a distance of 50 m. Marksmanship was assessed prior to training, and at 73 and 80 h into Hell Week. Volunteers were randomly assigned to 1 of 4 treatments: 100, 200, or 300 mg of caffeine or a placebo. Dosing occurred 72 h after training commenced. RESULTS: The combined effects of almost 73 h of total sleep deprivation and operational and environmental stress degraded all marksmanship accuracy measures (p < 0.05) as shown by the 37.5% increase in percent of targets missed, 38% increase in distance from center of mass of the target, and the 235% increase in shot group tightness. Sighting time increased by 53% or 3.1 s after 73 h of sleep deprivation (p < 0.05). Sighting time was significantly faster in sleep deprived individuals after taking 200 or 300 mg of caffeine compared with placebo or 100 mg of caffeine. No differences in accuracy measures between caffeine treatment groups were evident at any test period. CONCLUSION: During periods of sleep deprivation combined with other stressors, the use of 200 or 300 mg of caffeine enabled SEAL trainees to sight the target and pull the trigger faster without compromising shooting accuracy.
adarqui:
Effects of Exercise, Bedrest and Napping on Performance Decrement During 40 Hours
Young male Naval volunteers were denied normal noclurnal sleep and maintained on a 60-min lreatment-160-min testing schedule during 40 consecutive hrs. Ten subjects bicycled, 20 subjects controlled EEG activity during bedrest, and 10 subjects napped. Eight measures of addition, auditory vigilance, mood, and oral temperature were obtained. The Bedrest group showed significant impairment on all eight measures, and thus, gave no support to lite forced-rest theory of sleep function. The Exercise group was worse than the Nap and Bedrest groups for all measures. In spite of fragmented, reduced sleep (about 3.7 hrs per 24 hrs), the Nap group had no impairment on six of the measures. The results suggest that exercise increases the impairment due to sleep loss, and naps reduce or remove this impairment. Bedrest is not a substitute for sleep.
Sleep-dependent learning: a nap is as good as a night
The learning of perceptual skills has been shown in some cases to depend on the plasticity of the visual cortex1 and to require post-training nocturnal sleep2. We now report that sleep-dependent learning of a texture discrimination task can be accomplished in humans by brief (60? 90 min) naps containing both slow-wave sleep (SWS) and rapid eye movement (REM) sleep. This nap-dependent learning closely resembled that previously reported for an 8-h night of sleep in terms of magnitude, sleep-stage dependency and retinotopic specificity, and it was additive to subsequent sleep-dependent improvement, such that performance over 24 h showed as much learning as is normally seen after twice that length of time. Thus, from the perspective of behavioral improvement, a nap is as good as a night of sleep for learning on this perceptual task.
Impact of Ramadan on physical performance in professional soccer players
ABSTRACT
Objective: Ramadan is a period of daylight abstention from liquid or solid nutrients. As sports continue to be scheduled, an understanding of the effects of Ramadan on Muslim athletes is warranted.
Design: Two Algerian professional soccer teams (55 men) were studied. Field tests of physical and soccer performance were collected before, at the end and 2 weeks after Ramadan in 2004. Players were queried on sleeping habits and personal perception of training and match performance.
Setting: Field setting at club training ground.
Main outcome measures: Performance on fitness and skill tests.
Results: Performance declined significantly (p<0.05) for speed, agility, dribbling speed and endurance, and most stayed low after the conclusion of Ramadan. Nearly 70% of the players thought that their training and performance were adversely affected during the fast.
Conclusions: The phase shift of food intake and disruption of sleep patterns affect actual and perceived physical performance. Islamic athletes need to explore strategies that will maximise performance during Ramadan.
100m200m:
--- Quote from: adarqui on June 04, 2009, 08:17:41 pm ---1. Electro-mechanical response times and muscle strength after sleep deprivation.
--- Quote ---The results suggest that subjects who have undergone 60 h of SD can react as fast, and with as much force, as those who have had 7 h of sleep per night.
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2. Physical performance and physiological responses following 60 hours of sleep deprivation.
--- Quote ---These results suggest that sleep loss of up to 60 h will not impair the capability for physical work, a finding of considerable importance in sustained military operations which frequently involve the combination of both physical and mental tasks.
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3. The effect of partial sleep deprivation on weight-lifting performance
--- Quote ---Results indicate that submaximal lifting tasks are more affected by sleep loss than are maximal efforts, particularly for the first two nights of successive sleep restriction.
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7. The effects of two alternative timings of a one-hour nap on early morning performance.
--- Quote ---It was concluded that a one-hour nap could counteract the late night performance decrement.
--- End quote ---
--- End quote ---
1,2, and 3 make it seem like it would be better to skip sleep altogether than to sleep for a short time the night before some type of athletic event. However, 7 looks like it says the opposite.
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