Dose-response relationship between light exposure and cycling performance.
Light has a stimulating effect on physical performance if scheduled according to the chronotype, but dose-dependent effects on performance have not yet been examined. Three groups of healthy men (25.1 ± 3.1 years) were exposed to light for different durations in a parallel group design before a 40-min time-trial. In each group, subjects were exposed to either bright light (BL, 4420 lx) or moderate light (ML, 230 lx) in a randomized order in a crossover design. The durations of light exposure were 120 min prior to and during exercise (2HEX; n = 16), 60 min prior to and during exercise (1HEX; n = 10), or only for 60 min prior to exercise (1H; n = 15). Total work performed during the time-trial in kJ in the 2HEX group was significantly higher in the BL setting (527 kJ) than in ML (512 kJ) (P = 0.002), but not in 1HEX (BL: 485 kJ; ML: 498 kJ) or 1H (BL: 519 kJ; ML: 514 kJ) (P = 0.770; P = 0.485). There was a significant (P = 0.006) positive dose-response relationship between the duration of light exposure and the work performed over the three doses of light exposure. A long duration light exposure is an effective tool to increase total work in a medium length time-trial in subjects normalized for their individual chronotype.
Department of Sport, Exercise and Health, Division Sports and Exercise Medicine, University of Basel, Basel, Switzerland.
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Knaier
Department of Sport, Exercise and Health, Division Sports and Exercise Medicine, University of Basel, Basel, Switzerland.
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Meister
Department of Sport, Exercise and Health, Division Sports and Exercise Medicine, University of Basel, Basel, Switzerland.
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Aeschbacher
Department of Sport, Exercise and Health, Division Sports and Exercise Medicine, University of Basel, Basel, Switzerland.
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Gemperle
Department of Sport, Exercise and Health, Division Sports and Exercise Medicine, University of Basel, Basel, Switzerland.
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Rossmeissl
Center for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland.
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Cajochen
Department of Sport, Exercise and Health, Division Sports and Exercise Medicine, University of Basel, Basel, Switzerland.
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Schmidt-Trucksäss
D000328:Adult; D054874:Athletic Performance; D001642:Bicycling / Q000502:physiology*; D002940:Circadian Rhythm; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D013997:Time Factors; D055815:Young Adult
Bright light; chronotype; circadian rhythm; physical performance; time-trial