Effect of Cooling Between Exercise Bouts onFemale Exercise Performance in The Heat

Abstract

The purpose of this study was to examine the effect of body cooling between exercise bouts on high-intensity exercise performance in the heat. In a randomized crossover design, eighteen （9 males and 9 females） habitually trained subjects performed two （first and second half） cycling exercises with a 15-minute rest （half-time; HT） in the heat （35℃, 50% relative humidity）．The first and second half exercises consisted of 25-minute constant-paced cycling （55% of maximal oxygen uptake） and a 5-minute time trial, respectively. During HT, the participants were assigned to CON condition （ingesting 5g/kg of fluid at room temperature） or COOL condition （ingesting 5g/kg of ice slurry and wearing a cooling vest which can cool the neck, upper body, back, and side）．In males, the mean power output during time trial in the second half was significantly improved in the COOL condition compared with the CON condition, but this improvement was not observed in females. In the cool condition, physiological and subjective indicators in the HT and second half improved in both males and females. These results suggest that there was a gender difference in the effect of body cooling during the HT in the heat. In conclusion, the combination of internal and external cooling used in this study may reduce the risk of heat-related illness, but may not improve high-intensity exercise performance in females.