The purpose of this study was designed to examine the effect of exposure to two levels of light intensity (bright; 5000 lux and dim; 50 lux) prior to supramaximal cycle exercise on performance and energy supply. Double determinations were carried out for each subject at the same time on separate days. One day, supramaximal exercise after bright light exposure for ninety-minutes and the other day, after dim light exposure. Eight male long-distance runners, who aged 20.1 ± 0.6 (M ± SD) years old volunteered to take part in the present study. They performed 45-sec supramaximal exercise using a cycle ergometer in a light intensity of 500 lux. The mean power output was measured during supramaximal exercise, and blood glucose, lactate, ammonia, adrenaline and noradrenaline concentrations were measured at rest, immediately after bright or dim light exposure, and immediately after, and 2.5, 5.0, 7.5 min after the supramaximal exercise. The mean power output of supramaximal exercise was 467.7 ± 39.6 (M ± SD) watt for bright light exposure and 461.7 ± 40.0 (M ± SD) watt for dim light exposure. It was observed that the bright and dim light exposures prior to exercise do not affect in power output of supramaximal cycle exercise. Blood glucose concentration immediately after supramaximal exercise was significantly lower after bright light exposure compared to dim light (p<0.05). There was no effect of bright and dim light exposures on blood lactate concentration following supramaximal exercise. No significant difference was found in blood ammonia concentration after supramaximal exercise between bright and dim light exposures. From these results, it was cleared that the bright light stimulation prior to supramaximal exercise appeared to decrease the glucose level, but not related to prine nucleotide cycle and physical performance.

DESCENTE SPORTS SCIENCE Vol.22/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE