Effects of endurance training on thermoregulation in females.

Thermoregulatory responses to heat have been evaluated at rest in 27 university students; 11 female competitive athletes, 8 male non-athletes, and 8 female non-athletes. They rested for 2 h in an ambient temperature of 32 degrees C, 40% RH with their legs immersed up to the knees in a stirred water bath of 42 degrees C. Sweat rates of the female athletes were higher than the female non-athletes, but lower than the male non-athletes. Core temperature threshold for sweating was significantly lower in the female athletes than in the male and female non-athletes. The slope in sweat rate/core temperature relationship of the female athletes was nearly parallel to that of the female non-athletes. The thermoregulatory responses observed in the female athletes are thought to be comparable to those produced by heat adaptation. Comparing the heat responses in male and female non-athletes, no distinct sexual differences were observed in the rise in core temperature, mean skin temperature, and the core temperature threshold for sweating. On the other hand, the slope in the sweat rate/core temperature relationship was significantly steeper in males than in females. The beneficial modifications of heat responses demonstrated in the present study in female athletes are similiar to those observed in male athletes.