Abstract

Four men and four women with comparable maximal aerobic capacities (64.2 and 65.7 ml/kg LBM/min, respectively) and equal surface areas and surface area-tomass ratios underwent a 3-h heat stress test (Tdb = 36 degrees C; Twb = =O degrees C; VO2 = 1.0 l/min) before and after a 10-day acclimation to humid heat (Tdb = 36 degrees C; Tbw = 32 degrees C). Women were tested during both pre- and postovulation (pre-OV, post-OV). Prior to acclimation, pre-OV women exhibited the longest tolerance times and lowest rectal temperatures (Tre) andheart rates (HR) throughout testing. Men secreted considerably more sweat per unit area than did women in either phase of the cycle, yet they demonstrated shorter tolerance times and higher body temperatures and HR. During post-OV, women reacted similarly to men except that their sweat rates and HR values were significantly lower. Following acclimation, the Tre and HR of the men andwomen were similar, whereas the discrepancy between the sweat rates was magnified. It was concluded that aerobic capacity is an important factor to be considered when men and women are compared in the heat. When fitness levels are similar, the previously reported sexrelated differences in response to an acute heat exposure seem to disappear, except for the higher sweat rate for men. Verf.-Referat