Gender differences in thermoregulation.

Women differ from men in thermal responses to exogenous heat load and heat loss as well as to endogenous heat load during exercise, because they usually have a larger ratio of body surface to body mass, a greater subcutaneous fat content, and lower exercise capacity. When these differences are eliminated in experimental studies, it appears that women's sweating response to heat load is still smaller than that of men, but they are able to maintain their core body temperature on a similar level to that of men as a result of greater evaporative efficiency of sweating. In addition, the changing rate of sex hormone release during the menstrual cycle modifies thermoregulation in women, so there are differences in resting body temperature and thermal responses to positive or negative heat loads depending on the phase of the cycle. In this review, the changes in thermoregulation in young women taking oral contraceptives and those associated with the menopause and hormonal replacement therapy are also described.