Sex differences in acclimation to a hot dry environment

Sex-related differences in acclimation to a hot-dry environment were evaluated in ten males and nine females. The subjects were exposed during early spring to a hot- dry climate: 49^DC, 20% rh for 6 consecutive days. Exposures lasted 120 min: lOmin rest, 50min walk (l-34ms^_1), lOmin rest, 50min walk. Heart rate, rectal temperature (T_rc), mean skin temperature (7^), and heat storage dropped significantly for both sexes (p <0 05) from the 1st to the 6th day, with no significant changes (p > 005) between the last 2 days. In spite of similar metabolic rates, similar sweat rate and lower heat gain by radiation and convection for the females, their T_re and T_sk remained significantly higher (p< 0 05) than those for the males at the end of acclimation. It was suggested that the thermoregulatory set-point is higher for unacclimated women than for men, and that this difference does not disappear with acclimation.