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Dose–response relationship between light exposure and cycling performance
Author(s) -
Knaier R.,
Meister S.,
Aeschbacher T.,
Gemperle D.,
Rossmeissl A.,
Cajochen C.,
SchmidtTrucksäss A.
Publication year - 2016
Publication title -
scandinavian journal of medicine and science in sports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.575
H-Index - 115
eISSN - 1600-0838
pISSN - 0905-7188
DOI - 10.1111/sms.12535
Subject(s) - chronotype , crossover study , time trial , dose–response relationship , medicine , zoology , cycling , circadian rhythm , biology , placebo , heart rate , blood pressure , alternative medicine , pathology , history , archaeology
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.