Sleep and exercise: a reciprocal issue?

Sleep, circadian rhythms, and athletic performance

The purpose of this study was to determine the effect of one night's sleep deprivation on anaerobic performance in the morning and afternoon of the following day. Thirteen healthy males were studied twice in a balanced, randomized design. The experiment consisted of two conditions 1 week apart. In the sleep deprivation condition (SDN) subjects remained awake overnight and in the control condition (reference night, RN) the same subjects slept at home, retiring between 2230 and 2330 hours, as decided individually, and rising at 0500 hours. In both conditions, activity, sleep and diet were monitored by actimetry and daily activity and dietary diaries. Physical performance testing was carried out at 0600 hours and at 1800 hours after the one night of sleep and the one night of sleep deprivation. At each test occasion, subjects were measured for maximal power ( P(max)), peak power ( P(peak)) and mean power ( P(mean)). Blood lactate concentrations were measured at rest, at the end of the force-velocity ( F- V) test, just before and just after the Wingate test and again 5 min later. Oral temperatures were measured every 2 h. In both conditions, the results showed a circadian rhythm in temperature. Analysis of variance revealed a significant (sleep x time of day of test) interaction effect on P(peak), P(mean) and P(max). These variables improved significantly from morning to afternoon after RN and SDN. The reference night was followed by a greater improvement than the SDN. 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.

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

We investigated the physiological consequences of the most challenging mountain ultra-marathon (MUM) in the world: a 330-km trail run with 24000 m of positive and negative elevation change. Neuromuscular fatigue (NMF) was assessed before (Pre-), during (Mid-) and after (Post-) the MUM in experienced ultra-marathon runners (n=15; finish time =122.43 hours 617.21 hours) and in Pre- and Post- in a control group with a similar level of sleep deprivation (n=8). Blood markers of muscle inflammation and damage were analyzed at Pre- and Post-. Mean 6 SD maximal voluntary contraction force declined significantly at Mid- (213617% and 210616%, P,0.05 for knee extensor, KE, and plantar flexor muscles, PF, respectively), and further decreased at Post- (224613% and 226619%, P,0.01) with alteration of the central activation ratio (224624% and 228634% between Pre- and Post-, P,0.05) in runners whereas these parameters did not change in the control group. Peripheral NMF markers such as 100 Hz doublet (KE: 218618% and PF: 220615%, P,0.01) and peak twitch (KE: 233612%, P,0.001 and PF: 219614%, P,0.01) were also altered in runners but not in controls. Post-MUM blood concentrations of creatine kinase (371963045 Ul? 1 ), lactate dehydrogenase (11456511 UI?L 21 ), C-Reactive Protein (13.167.5 mg?L 21 ) and myoglobin (449.36338.2 mg?L 21 ) were higher (P,0.001) than at Pre- in runners but not in controls. Our findings revealed less neuromuscular fatigue, muscle damage and inflammation than in shorter MUMs. In conclusion, paradoxically, such extreme exercise seems to induce a relative muscle preservation process due likely to a protective anticipatory pacing strategy during the first half of MUM and sleep deprivation in the second half.

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Alterations of Neuromuscular Function after the World's Most Challenging Mountain Ultra-Marathon

Sleep deprivation or partial sleep loss are common in work conditions as rotating shifts and prolonged work hours, in sustained military operations and in athletes competing in events after crossing several time zones or engaged in ultramarathon or triathlon events. Although it is well established that sleep loss has negative effects on mental performance, its effects on physical performance are equivocal. This review examines the latter question in light of recent studies published on this problem. Sleep deprivation of 30 to 72 hours does not affect cardiovascular and respiratory responses to exercise of varying intensity, or the aerobic and anaerobic performance capability of individuals. Muscle strength and electromechanical responses are also not affected. Time to exhaustion, however, is decreased by sleep deprivation. Although ratings of perceived exertion always increased during exercise in sleep-deprived (30 to 60 hours) subjects compared with normal sleep, this is not a reliable assessment of a subject's ability to perform physical work as the ratings of perceived exertion are dissociated from any cardiovascular changes in sleep deprivation. Examination of the various hormonal and metabolic parameters which have been measured in the studies reviewed reveals that the major metabolic perturbations accompanying sleep deprivation in humans are an increase in insulin resistance and a decrease in glucose tolerance. This may explain the reduction in observed time to exhaustion in sleep-deprived subjects. The role of growth hormone in mediating altered carbohydrate metabolism may be of particular relevance as to how sleep deprivation alters the supply of energy substrate to the muscle.

Sleep Deprivation and the Effect on Exercise Performance

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.

Pope J

Papers

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