Effect of bright light on cycling performance.

Abstract

The purpose of this study was to examine the effect of exposure to three levels of light intensity during cycling on average power output during an all-out 20-min bout of cycle ergometry. Twelve male competitive cyclists, with a mean age of 24.3 +/- 3.2 yr, were tested on four separate occasions. During each test session, participants were instructed to produce the highest possible average power output during a 20-min bout of cycle ergometry. Session 1 served as a adaptation trial and was conducted in normal room lighting (approximately 250 lux). In subsequent sessions each participant exercised while sitting in front of a light box. Light intensity was experimentally manipulated through the use of sunglasses that provided high, medium, and low light filtration. Light condition order was counterbalanced. Measurements of heart rate, muscle pain, local perceived exertion, metabolism, and alertness were made during exercise. Mood was assessed before and following exercise with the POMS-BI. There were no statistically significant differences in the average total power output in the 1,411 lux (274.9 +/- 21.8 W), 2,788 lux (274.4 +/- 20.5 W), and 6,434 lux (270.3 +/- 19.8 W) light conditions. The difference between the average power output in the brightest and least bright condition (4.6 W) was approximately one-fourth of a pooled SD (d = 0.22). There were no significant differences among the conditions in alertness, leg muscle pain, perceived exertion, heart rate, VO2, or mood responses to the exercise. It is concluded that exposure to bright light resulting in estimated retinal exposures ranging from 1,411 to 6,434 lux did not have a large or systematic influence on the performance of 20 min of maximal cycle ergometry.