Heat Acclimation Training Research Articles

SWEAT GLAND ACTIVITY FOLLOWING CHOLINERGIC AND THERMAL TRAINING

Increased sweating is an important counter-mechanism to minimize heat distress. Adaptation in sweating can occur through several modes including, warm-water immersion and exposure to cholinergic agonists, like pilocarpine. Iontophoresic introduction of pilocarpine has been shown to cause an acute sweat response, but has not been studied to assess its sustaining effects. PURPOSE: To compare the physiological responses of chronic exposure of localized thermal and chemical sweat glands stimulation. METHODS: Four healthy, males (27 ± 5 yrs; 177.8 ± 6.4 cm; 77.2 ± 6.3 kg) served as their own controls. Sweat gland training consisted of 2-weeks of treatment, including 7 days of repeated exposure to pilocarpine to the right upper extremity (RUE), followed by 7 days of heat acclimation training (43 ° C moist heating packs) to the left upper extremity (LUE). Sweat rate (SR) and sweat gland density (SGD) were determined by pilocarpine stimulation on days 1, 7 and 14 on the RUE and LUE. RESULTS: Baseline readings of SR (6.17 ± 2.60 g/m2/min−1 and 5.11 ± 1.76) and SGD (125 ± 12 glands/cm2 and 108 ± 8) for the RUE and LUE did not significantly differ on day 1 (p > .05). Following cholinergic treatment, the RUE exhibited a 28% decrease in SGD (90 ± 33 glands/cm2) and a 46% reduction in SR (3.3 ± 1.48 g/m2/min−1). Following thermal stimulation the LUE displayed an increase in SGD of 24.2% (128 ± 6 glands/cm2) and a 37% increase in sweat productivity (SR = 7.63 ± 3.32 g/m2/min−1) (p < .05). CONCLUSIONS: These data suggest that sweat glands are more productive following thermal stimulation and less responsive with repeated exposure to cholinergic-agents.

Human metabolic responses to hyperthermia during mild to maximal exercise.

Human metabolic responses to hyperthermia during mild to maximal exercise.