This is part 3 of a series about the importance of sleep to athletes. Part 1 was “Improve Athletic Performance By Taking A Nap.” Part 2 was “Reduced Quality Of Sleep In Athletes.” Please subscribe to this blog for future installments and other interesting content.
We all miss sleep before important athletic events. There has been research on the effect of partial and total sleep deprivation on aerobic and anaerobic exercise performance. This information is important to all athletes, but especially to ultra-endurance athletes who, as a part of competitions become sleep deprived.
While it would be very unusual to not sleep at all before important competitions, it is commonplace to have reduced or disrupted sleep. The studies that have investigated the effects of such reduced sleep on performance have, surprisingly, not demonstrated a large decrement. For example, one study described the effects of one night of restricted sleep on athletes and found no change in gross motor function such as muscle strength and endurance running. Another similar study in females showed similar results with less of an effect upon gross motor functions than tasks that required rapid reaction times. In a study of eight swimmers, the effect of 2.5 hours of sleep for four consecutive nights was studied and no effect was observed in back and grip strength lung function, or swimming performance. However, mood state was altered with increases in measures of depression, tension, confusion, fatigue, and anger. With regard to anaerobic performance, a study examined the effects of a single night of 2.5 hours of sleep in a group of sedentary women and found no change in muscle strength. However, an effect on anaerobic performance appears to become more apparent after several nights of restricted sleep. This was demonstrated in a study of the effect of partial sleep loss (3 hours of sleep per night for 3 consecutive nights) on muscle strength. In this study, there was a decrease in maximal bench press, leg press, and deadlift, but not maximal bicep curl. Interestingly, however, sub-maximal efforts were significantly negatively affected for all four tasks to a greater degree than the maximal efforts. Furthermore, the largest impairments were found later in the protocol, which suggests that there is an accumulative effect of muscle fatigue from sleep loss. This last study may be of particular interest to long-course triathletes, who rely on muscular endurance, particularly in the cycling leg of races.
In the case of prolonged periods of no sleep, there are some interesting studies that have shown a large effect on performance. For example, 30 hours without sleep has been demonstrated to lead to decreased running performance This was shown in a trial in which participants ran, self-paced, on a treadmill for 30 minutes either after normal sleep or after 30 hours without sleep. The sleep-deprived performances were clearly inferior, with the participants covering an average of 6224 meters after normal sleep and 6037 meters after no sleep. Interestingly, the sleep-deprived participants had a similar perception of their effort in both performances. This suggests that sleep deprivation may lead to decreased running performances because of impaired perception of effort. In another study with similar results, there were significant decreases in average and total sprint time after 30 hours without sleep. In terms of anaerobic performance, a study of 24 hours of sleep deprivation in weightlifters showed no differences in the tasks measured, including snatch, clean and jerk, front squat, total volume load, and training intensity. However, the mood state of sleep-deprived participants was significantly negatively affected, including increased confusion. At 30 hours of sleep deprivation, however there does appear to be an effect on muscle strength. This was demonstrated in a study that showed decreased knee extension and flexion peak torque after no sleep for 30 hours, as compared to after normal sleep. The importance of the difference between 24 hours without sleep and longer durations of time without sleep was demonstrated, again, in another study that showed that anaerobic performances were unaffected after 24 hours of wakefulness but were impaired after 36 hours of wakefulness.
So, don’t worry about a single night of reduced sleep before a race. It does not appear to have a meaningful effect upon athletic performance. In contrast, a number of consecutive nights of reduced sleep does appear to affect muscle strength, especially sub-maximal strength, but does not appear to affect swimming performance. With regard to no sleep at all before exercise, 24 hours without sleep has not been shown to affect performance, but 30 hours or more without sleep has been shown to affect both aerobic and anaerobic performance. For those people who participate in overnight endurance races, either as a solo athlete or as part of a relay team, this information may be particularly important. Performance in such as situation is impaired and, as described above, an athlete may be unable to perceive this impairment aside from feeling grouchy.
Published March 22, 2015.
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