AIMTo investigate the sweat regulation mechanism of human body.

METHODSArm muscular work was performed on bicycle ergometer by eight healthy male subjects on 20 W and 40 W work loads lasting 10 min or 20 min in 16 degrees C and 21 degrees C ambient temperature. Sweat, metabolic rate and corresponding skin and core temperature changes were measured during different periods.

RESULTSSweat varied directly with ambient temperature and there were the corresponding changes in mean skin temperature, rectal temperature and metabolic rate. And when the work load was elevated, the skin temperature at chest and metabolic rate increased as sweat increased. There were no differences in the physiological indices between 20 W 20 min and 20 W 10 min, but mean skin temperature and sweat rate during 40 W 20 min work were higher than 40 W 10 min while metabolic rate did not change. The time when chest temperature arrived at the threshold was in correspondence with obvious sweat onset. Both local skin temperature at chest and metabolic rate were significantly correlated with sweat, but the latter was stronger. The regression equation relating metabolic rate and sweat rate was compound function.

CONCLUSIONSkin temperature was important for sweat onset, and the sweat predicted model based on the metabolic rate or ambient temperature was more suitable and practical.