THERMOREGULATION DURING EXERCISE IN RELATION TO SEX AND AGE

The thermoregulatory responses to 1 h exercise of 14 male (age range 18-65 year) and 7 female (age range 18-46 year) athletes and 4 (3♂ and 1 ♀) non-athletic subjects have been investigated in a moderate environment (Tdb=21‡ C, Twb=15‡ C and rh<50%) and analysed in relation to age, sex, and maximum aerobic power output (VO2 max). The maximal sweat loss (Msw max) under the given conditions was closely related (r=+0.90) to VO2 max and for a given relative work load (%VO2 max), rectal (Tre) and mean skin (-Tsk) temperatures was the same in all subjects. Sweat loss (004dsw) was linearly related to total heat production (H) and to peripheral tissue heat conductance (K) and if expressed in relative terms (%Msw max) was linearly related to Tre. For a given Tre relative sweat rate was identical in the groups studied. From these results it would seem that during exercise Tre rises to meet the requirements of heat dissipation by establishing a thermal gradient from core to skin and stimulating sweating in proportion to maximal capacity of the system. Thus provided the thermal responses to work were standardised using the appropriate physiological variables, there was no evidence to be found for differences in thermoregulatory function which could be ascribed to sex or age. © 1979 Springer-Verlag.