Abstract

Four acclimated men and four acclimated women exercised at 30 VO2max in a hot-humid environment and a hot-dry environment. Variables recorded during heat stress tests, rectal temperature (Tre), mean skin temperature, heart rate (HR), total body sweat rate (Msw), chest sweat rate (chest msw), sweat gland activity per unit surface area (pSGA) on the chest, and sweat gland flow (SGF) on the chest were recorded. Sweating efficiency was determined as the ratio of required to observed sweating. There were no differences between sexes or environments in Tre or HR. Both sexes had significantly lower MSW and chest msw in the humid heat compared with the dry heat. The women maintained significantly lower Msw and chest msw than the men in the humid heat, with significantly higher sweating efficiency. There were no differences in sweating rates or efficiency between sexes in the dry heat. In both environments,the men recruited a significantly lower percentage of their available sweat glands than did the women. The reduction in pSGA in the humid heat among the women allowed the women to conserve body water through improved sweating efficiency. However, the men had a larger apparent reserve to increase sweating in more severe dry heat. Verf.-Referat