Circadian variation in swim performance
Open Access
- 1 February 2007
- journal article
- Published by American Physiological Society in Journal of Applied Physiology
- Vol. 102 (2), 641-649
- https://doi.org/10.1152/japplphysiol.00910.2006
Abstract
Previous findings of time-of-day differences in athletic performance could be confounded by diurnal fluctuations in environmental and behavioral “masking” factors (e.g., sleep, ambient temperature, and energy intake). The purpose of this study was to examine whether there is a circadian rhythm in swim performance that is independent of these masking factors. Experienced swimmers ( n = 25) were assessed for 50–55 consecutive hours in the laboratory. The swimmers followed a 3-h “ultra-short” sleep-wake cycle, involving 1 h of sleep in darkness and 2 h of wakefulness in dim light, that was repeated throughout the observation. The protocol distributes behavioral and environmental masking factors equally across the 24-h period. Each swimmer was scheduled to perform six maximal-effort 200-m swim trials that were distributed equally across eight times of day ( n = 147 trials). Each trial was separated by 9 h. A cosine fit of intra-aural temperature data established the time of the lowest body temperature (Tmin). Swim performances were z-transformed and compared across the eight times of day and across twelve 2-h intervals relative to Tmin. Analysis of covariance, controlling for trial number, revealed a significant ( P < 0.001) pattern in swim performance relative to environmental and circadian times of day. Performance peaked 5–7 h before Tmin(∼2300) and was worst from 1 h before to 1 h after Tmin(∼0500). Mean swim performance was 169.5 s; circadian variation from peak to worst performance was 5.8 s. These data suggest a circadian rhythm in athletic performance independent of environmental and behavioral masking effects.Keywords
This publication has 45 references indexed in Scilit:
- Diurnal variation in cycling performance: Influence of warm-upJournal of Sports Sciences, 2005
- MORNING VS. EVENING MAXIMAL CYCLE POWER AND TECHNICAL SWIMMING ABILITYJournal of Strength and Conditioning Research, 2004
- Warm Up IISports Medicine, 2003
- Effect of time of day on force variation in a human muscleMuscle & Nerve, 1999
- Circadian Variation in Sports PerformanceSports Medicine, 1996
- Effects of a Selective Sleep Deprivation on Subsequent Anaerobic PerformanceInternational Journal of Sports Medicine, 1996
- Short‐term memory, alertness and performance: a reappraisal of their relationship to body temperatureJournal of Sleep Research, 1992
- Maximal Aerobic Exercise Following Prolonged Sleep DeprivationInternational Journal of Sports Medicine, 1989
- Influence of time of day on all-out swimming.British Journal of Sports Medicine, 1983
- Influence of time of day on reactions to cycling at a fixed high intensity.British Journal of Sports Medicine, 1983