ABSTRACT

　The purpose of this study was to investigate the effect of body cooling with the fan cooling jacket on body temperature responses during recovery after exercise when exposed to high solar radiation in an outdoor hot environment. Nine healthy male subjects cycled using ergometer until their rectal temperature increased to 38.50℃ in hot outdoor environments （31-35℃ , 48-65% relative humidity, and 950-1150 W/m2 solar radiation）， followed by body cooling recovery in warm indoor environments （28-31 ℃ room temperature and 50-60% relative humidity）．Subjects repeatedly performed the cycling exercise protocol, which consisted of one set of 5 min at a load of 1.5 watt/kg body weight and 15 min at a load of 2.0 watt/ kg body weight at 60 rpm. Body cooling recovery consisted of cold water ingestion （10℃ : CON） or cold water ingestion + the use of the fan cooling jacket （FAN） in random order until the rectal temperature decreased to 37.75℃ . The time for the rectal temperature to reach 38.5℃ did not differ between the two trials. The rate of decrease in rectal temperature at recovery tended to be higher in FAN trial than in CON trial （P = 0.082）．The rate of decrease in ear canal temperature was higher in FAN trials than in CON trials（P = 0.002）．The rate of decrease in mean skin temperature at the first 20 min of recovery was higher in FAN than in CON trial（P = 0.013）．Body cooling recovery with the fan cooling jacket in addition to cold water ingestion may be effective in reducing elevated ear canal and skin temperatures during exercise in the heat under a clear sky, but may be difficult to decrease rectal temperature.

DECENTE SPORTS SCIENCE Vol.44/The DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE