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All conclusions of studies will be listed in this original post (TABLE OF SUMMARIES) for quick reference.


This thread goes out to our dear friend CoolColJ:

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

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.

1. Electro-mechanical response times and muscle strength after sleep deprivation.

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.

2. Physical performance and physiological responses following 60 hours of sleep deprivation.

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.

3. The effect of partial sleep deprivation on weight-lifting performance

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.

4. Effects of caffeine, sleep loss, and stress on cognitive performance and mood during U.S. Navy SEAL training

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.

5. Caffeine effects on marksmanship during high-stress military training with 72 hour sleep deprivation.

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.

6. Sleep-dependent learning: a nap is as good as a night

Thus, from the perspective of behavioral improvement, a nap is as good as a night of sleep for learning on this perceptual task.

7. The effects of two alternative timings of a one-hour nap on early morning performance.

It was concluded that a one-hour nap could counteract the late night performance decrement.

8. Effects of Exercise, Bedrest and Napping on Performance Decrement During 40 Hours

... and naps reduce or remove this impairment. Bedrest is not a substitute for sleep.

9. Impact of Ramadan on physical performance in professional soccer players

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.

10. Physical performance responses during 72 h of military operational stress.

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.

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.

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.

12.

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.

13. Sports, Sleep, and Circadian Rhythms : Circadian Rhythms and Enhanced Athletic Performance in the National Football League

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.

14. Diurnal Rhythm of the Muscular Performance of Elbow Flexors During Isometric Contractions

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.

15. Circadian performance differences between morning and evening 'types'

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.

16. CIRCADIAN RHYTHMS IN HUMAN MUSCULAR EFFICIENCY: CONTINUOUS PHYSICAL EXERCISE VERSUS CONTINUOUS REST. A CROSSOVER STUDY

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)

17. Circadian rhythms have no effect on cycling performance

18. Time-of-day dependence of isokinetic leg strength and associated interday variability.

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.

19. Effects of dehydration on isometric muscular strength and endurance.

These results provide evidence that isometric strength and endurance are unaffected 3.5 h after dehydration of approximately 4% body mass.

20. Sleep deprivation induced anxiety and anaerobic performance

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.

21. The role of a short post-lunch nap in improving cognitive, motor, and sprint performance in participants with partial sleep deprivation

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.

22. Effects of One Night of Partial Sleep Deprivation upon Diurnal Rhythms of Accuracy and Consistency in Throwing Darts

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.

23. Effects of a selective sleep deprivation on subsequent anaerobic performance

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.

24. Effects of one night's sleep deprivation on anaerobic performance the following day

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.

25. Sleep deprivation and exercise

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.

26. The Impact of Sleep Deprivation on Decision Making: A Review

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.

27. The Acute Effects of Twenty-Four Hours of Sleep Loss on the Performance of National-Caliber Male Collegiate Weightlifters

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.

28. Effect of sleep deprivation on tolerance of prolonged exercise

These findings suggest that the psychological effects of acute sleep loss may contribute to decreased tolerance of prolonged heavy exercise.

29. Sleep deprivation and cardiorespiratory function

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.

30. Caffeine Use in Sports: Considerations for the Athlete.

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.

31. Effects of Caffeine on Prolonged Intermittent-Sprint Ability in Team-Sport Athletes.

Conclusion: This study revealed that acute caffeine ingestion can significantly enhance performance of prolonged, intermittent-sprint ability in competitive, male, team-sport athletes.

32. 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.

33. Multiple Effects of Caffeine on Simulated High-Intensity Team-Sport Performance.

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.

*** READ THE ORIGINAL POST OF EACH THREAD TO VIEW THE TABLE OF CONTENTS/SUMMARY OF EVERY STUDY POSTED IN THE THREAD ***

This is going to be a very fun & interesting part of our forum.

This - is - the - KNOWLEDGE VAULT.

ya i know that sounds cool, thanks.

this section will be vital in spreading knowledge throughout the forum. it will become a table of contents for performance training of sorts.


anyway, you can start your own topics on various issues. the goal here is to supply relevant peer review studies. we want to keep this section "scientific", but replies can still be opinionated & discussion oriented.

the studies may get mixed up in all of the discussion, but that is why we will have all of the summaries of each study in the original post. eventually, if these threads grow out of control, there will be links to the specific posts that contain the studies, so people can easily reference them.

so basically the rules are simple, reply with a study or comment.

peace

All conclusions of studies will be listed in this original post (TABLE OF SUMMARIES) for quick reference.


Post anything related to tendon / muscle / joint stiffness & performance. This could be anything related to different training methods & their effect on stiffness, and the effect of this training on performance (sprinting/jumping etc).




1. Influence of elastic properties of tendon structures on jump performance in humans

Although the stiffness was not significantly related to absolute jump height in either vertical jump, it was inversely correlated with the difference in jump height between the vertical jumps performed with and without countermovement. The results suggested that the stiffness of tendon structures has a favorable effect on stretch-shortening cycle exercise, possibly due to adequate storage and recoil of elastic energy.

2. Effects of isometric squat training on the tendon stiffness and jump performance

These results suggest that isometric squat training changes the stiffness of human tendon aponeurosis complex in knee extensors to act negatively on the effects of pre-stretch during stretch-shortening cycle exercises.

3. Age-related neuromuscular function during drop jumps

These different activation patterns are in line with the mechanical behavior of GM (medial gastroc) showing significantly less fascicle shortening and relative TT (tendon tissue) stretching in the braking phase in the elderly than in the young subjects. These results suggest that age-specific muscle activation patterns as well as mechanical behaviors exist during DJs.

4. Influence of leg stiffness and its effect on myodynamic jumping performance.

The leg and ankle stiffness values were higher when the contact times were shorter. This means that by influencing contact time through verbal instructions it is possible to control leg stiffness.

5. Leg stiffness primarily depends on ankle stiffness during human hopping

Thus, we conclude that the primary mechanism for leg stiffness adjustment is the adjustment of ankle stiffness.

6. Muscle performance during maximal isometric and dynamic contractions is influenced by the stiffness of the tendinous structures

Power, force, and velocity parameters obtained during the jumps were significantly correlated to tendon stiffness. These data indicate that muscle output in high-force isometric and dynamic muscle actions is positively related to the stiffness of the tendinous structures, possibly by means of a more effective force transmission from the contractile elements to the bone.

7. Effect of landing stiffness on joint kinetics and energetics in the lower extremity.

Overall, the muscular system absorbed 19% more of the body's kinetic energy in the soft landing compared with the stiff landing, reducing the impact stress on other body tissues. The ankle plantarflexors provided the major energy absorption function in both conditions, averaging 44% of the total muscular work done followed by the knee (34%) and hip (22%) extensors.

8. Effects of Plyometric and Weight Training on Muscle-Tendon Complex and Jump Performance.

Conclusion: These results indicate that the jump performance gains after plyometric training are attributed to changes in the mechanical properties of muscle-tendon complex, rather than to the muscle activation strategies.

9. Relationships between three potentiation effects of plyometric training and performance

Conclusions: Plyometric training specifically potentiated the normalized EMG, tendon stiffness and elastic energy utilization in the myotendinous complex of the triceps surae. Although these changes are possibly essential determinants, only increases of tendon stiffness were observed to correlate with performance improvements.

10. Effects of different duration isometric contractions on tendon elasticity in human quadriceps muscles

Stiffness increased significantly for the long-duration protocol, but not for the short-duration protocol.

The present study demonstrates a greater increase in stiffness of human tendon structures following isometric training using longer duration contractions compared to shorter contractions. This suggests that the changes in the elasticity of the tendon structures after resistance training may be affected by the duration of muscle contraction.

11. Effects of isometric training on the elasticity of human tendon structures in vivo

Thus the present results indicate that isometric training increases the stiffness and Young's modulus of human tendon structures as well as muscle strength and size. This change in the tendon structures would be assumed to be an advantage for increasing the rate of torque development and shortening the electromechanical delay.

12. Effect of habitual running on human Achilles tendon load-deformation properties and cross-sectional area

The total running duration was ~43 h, distributed over 34 wk. Tendon-aponeurosis displacement during maximal voluntary contraction was unchanged. Tendon CSA also remained unchanged In conclusion, a total training stimulus of ~9 mo of running in previously untrained subjects was adequate to induce significant cardiovascular improvements, although it did not result in any changes in the mechanical properties of the triceps surea tendon-aponeurosis complex or in the dimensions of Achilles tendon.

13. Optimal muscle fascicle length and tendon stiffness for maximising gastrocnemius efficiency during human walking and running

14. On muscle, tendon and high heels

We conclude that long-term use of high-heeled shoes induces shortening of the GM muscle fascicles and increases AT stiffness, reducing the ankle's active range of motion. Functionally, these two phenomena seem to counteract each other since no significant differences in static or dynamic torques were observed.

not done yet, but done enough..

hangtime/frank dick chart calculators are up:

http://www.pure-dedication.com/index.php?option=com_content&view=article&id=67:art-calculators&catid=35:lab-adarq&Itemid=57

Questions/Comments/Discuss.

http://www.pure-dedication.com/index.php?option=com_content&view=article&id=57&Itemid=65

Use this section to discuss articles and videos any site. The videos to discuss in this section are to be "informative" in nature. Examples of these videos would be the Werner Gunthor video series, Holm vs Thomas series, HPCSport lectures on performance, etc... Purely entertainment-style videos have their own section: http://www.pure-dedication.com/forum/index.php?board=15.0

peace.

Questions/Comments/Discuss.