Thermal, metabolic, and cardiovascular changes in men and women during cold stress.

Our understanding of the responses of men and women to cold stress is extremely limited. Various scientists have suggested that there could be gender differences in thermoregulatory responses due to sexual dimorphism in body fatness and its distribution, in body surface area, and in mass. In addition, there are also several lines of evidence supporting the hypothesis that there are gender-specific physiological responses to body cooling. In cold water studies, women cool more rapidly than men when at rest; this potentially greater stimulus does not result in a greater metabolic response by the women. If both groups increase their metabolism by performing a prescribed amount of exercise, there are no differences in body cooling. However, if they exercise spontaneously, the women select a lower metabolic rate and experience greater body cooling. Thus, it appears that women are less thermally sensitive to cold water. In cold air stress women have a lower mean skin temperature than men, but this is not observed in peripheral skin sites. In contrast to cold water, women do not experience greater drops in deep body temperature than men in cold air. Furthermore, men may be more metabolically sensitive than women to cold air stress. Men also respond to cold air with a bradycardia and increased stroke volume, while women show no change in these parameters. Similarly, men show a greater blood pressure response than women to local cooling of a hand or the face. Many of these gender-specific responses cannot be explained fully by differences in body morphology and support the concept that men and women respond differently to the cold.