Sports Medicine Research: In the Lab & In the Field: Increased Illness Development Caused by Sleep Disturbances in Overreached Endurance Athletes: A Chain Reaction (Sports Med Res)
Tuesday, November 12, 2013

Increased Illness Development Caused by Sleep Disturbances in Overreached Endurance Athletes: A Chain Reaction

Evidence of disturbed sleep and increased illness in overreached endurance athletes

Hausswirth C, Louis J, Aubry A, Bonnet G, Duffield R, Le Meur Y. Med & Science in Sports & Exercise. 2013 Sept 24 [Epub ahead of print]

Take Home Message: Overreaching endurance athletes may be more likely to develop abnormal sleep quality and quantity as well as upper respiratory infections.

Many endurance athletes increase their training volume or intensity as an attempt to improve their physical performance. However, inadequate recovery can cause a short-term abnormal training response called “overreaching,” which potentially results in a decline in sleep quantity and quality and subsequently a higher risk of upper respiratory tract infections. Hausswirth and colleagues examined endurance athletes to determine if they experience abnormal sleep quantity and quality after they experience overreaching in response to an overload training program. Secondly, the authors tested if reduced sleep quality would be accompanied with higher incidence of upper respiratory tract infections among these athletes. Twenty-seven experienced male triathletes were randomly assigned to an overload training group (18 athletes) or a normal (control) training group (9 athletes). Training programs included a 1-week moderate training phase, followed by a 3-week period of overload training for the overload group or normal training for the control group, and then a subsequent 2-week taper. During the overload phase, the overload group trained at a 30% higher rate than their normal training load, while the control group continued their normal habitual training. Mood states (measured by the Profile of Mood States questionnaire) and upper respiratory tract illness symptoms and gastrointestinal discomfort were collected in every phase. The authors determined sleep quality every night of the six-week period by using wristwatch actigraphy. Nine of the eighteen athletes in the overload group were diagnosed as functionally overreached. During the overload phase, the functionally-overreached group demonstrated a decrease in sleep duration, sleep efficiency, and immobile time (time spent not moving while sleeping). These athletes improved in all three outcomes during the taper phase. Athletes who functionally overreached reported more upper respiratory tract infections during the overload and tapering phases (67%) compared with the control group (11%). 

This study indicated that triathletes who functionally overreach during periods of high-volume training experienced sleep disturbances and an increased incidence of upper respiratory tract illness. Perhaps if we educate coaches and athletes about these risks we can prevent overreaching, decrease illnesses, and increase sleep quality and quantity among our athletes. All of which are incredibly important for an athlete who is in the middle of training for competition. Adequate amounts of sleep are important for athletes because it is a crucial recovery time for the body and their performance suffers when they are exhausted. Clinicians should also take into consideration the fact that a decrease in sleep efficiency could negatively impact an athlete’s personal life (e.g., school, work). This could increase the athlete’s stress level, which could also impair their athletic performance. Impaired performance could lead an athlete to think they need to train harder, causing a viscous cycle of these effects. During this study, the reported illness symptoms and sleep disturbances peaked during the last week of the overload period, which could imply an accumulative effect. This would occur mostly during pre-season and mid-season because the athletes are conditioning and focusing on working toward their maximum competition level. If an athlete complains about their sleeping habits it could be interpreted as a reaction to overreaching while training. If we can recognize overreaching early this may allow us to alter their training regimen, possibly preventing the development of illness. The findings in this study support previous studies that reported that immunity is depressed during sustained periods of heavy training. This association suggests there is a link between the recuperative processes of sleep and the immune system. Therefore, we need to be aware of reported sleep disturbances and how the risk of overreaching may negatively affect an athlete’s competition.

Discussion Questions: Have you noticed a decrease in sleep quality and quantity and/or an increase of illness in athletes who are overreaching? Why do you think overreaching causes a decrease in sleep quality and quantity? This study focused on endurance athletes; do you think the same reactions would occur in sprint athletes?

Written By: Sara Dorsten
Reviewed By: Lisa Chinn and Jeffrey Driban

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Hausswirth C, Louis J, Aubry A, Bonnet G, Duffield R, & Le Meur Y (2013). Evidence of Disturbed Sleep and Increased Illness in Overreached Endurance Athletes. Medicine and Science in Sports and Exercise PMID: 24091995

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