Peripheral Sweat Gland Function Improves With Humid Heat Acclimation

摘要

Background: This study was conducted to determine if humid heat acclimation improves thermoregulatory function at the level of eccrine sweat gland. Methods: Thirteen male volunteers participated in this study, which consisted of 2 h of exercise in a thermal environment of 35 degrees C and 75% relative humidity for 8 consecutive days. All trials were randomized and consisted of four 25-min exercise intervals with 5 min of seated rest. The four exercise intervals consisted of two bouts of treadmill walking (3 mph, 3% grade) and two bouts of cycle ergometry (power output of 60 W). Heart rate and core temperature were measured each minute during the trials and whole-body sweat rate was calculated for the duration of the exposure. On days 1, 4, and 8 peripheral sweat production was induced via pilocarpine iontophoresis on the flexor surface of both forearms. Results: Mean rectal temperature and heart rate were significantly reduced by 0.5 degrees C and 17 bpm, respectively, and whole body sweat rate significantly increased by 20% during the 8-day heat acclimation protocol. Humid heat acclimation produced a significant 63% increase in pilocarpine-induced sweat rate. Conclusion: The results strongly suggest that heat acclimation improves sweat gland function via a peripheral mechanism.