ABSTRACT

　In this study, we investigated the effects of carbohydrate loading on hydration status and thermoregulatory responses during exercise in a hot environment. Ten healthy adult males consumed either a standard diet （CON condition; carbohydrate: 6.1±0.5 g/kg BW/day） or a high-carbohydrate diet （CL condition; carbohydrate: 11.2±0.6 g/kg BW/day） for three consecutive days. Total body water （TBW） was assessed using the stable isotope dilution method. Participants performed 40 minutes of cycling at 60% VO2max in a hot environment （31℃ , 70% relative humidity）． Rectal temperature（Tre） and mean skin temperature（Tsk） were measured before exercise and every 10 minutes during exercise. TBW after exercise was estimated by subtracting sweat loss from the pre-exercise TBW. Pre-exercise TBW was significantly higher in the CL condition compared to the CON condition （37.7 ± 4.7 kg vs. 37.0 ± 4.9 kg, p < 0.05）．After 40 minutes of exercise, both Tre and Tsk increased in both conditions, with no significant interaction. Since sweat loss did not differ significantly between the two conditions, post-exercise TBW remained significantly higher in the CL condition than in the CON condition（36.9±4.8 kg vs. 36.2±4.8 kg, p < 0.05）．In conclusion, while carbohydrate loading did not significantly alter thermoregulatory responses, it may help maintain body water content during exercise in a hot environment.

DECENTE SPORTS SCIENCE Vol.47/The DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE