A Comparison of the Physiological Responses in Young Men and Women to Heat and Cold Stress.

摘要

The current literature on male-female differences in response to thermal stress has been reviewed. Morphological differences of women (20% smaller body mass, 14% more body fat, 33% less lean body mass, but only 14-22% less surface area) impinge greatly on their relative ability to balance body heat production and losses. Women have greater body insulation against thermal transients when fully vasoconstricted (except on hands and feet) and a greater peripheral body 'shell' for a heat sink, but at the cost of (1) a greater burden of body fat to be transported, (2) less muscle mass and strength, and (3) a disproportionately smaller circulating blood volume. Women have lower blood hemoglobin concentrations, which necessitates higher cardiac output from their smaller hearts for equivalent muscular work, resulting in higher heart rates. In the heat, they generally show (1) relatively more peripheral blood pooling when vasodilated, (2) a greater increase in heart rate, (3) a greater tendency for circulatory embarrassment, (4) lower maximal sweat rates, (5) higher skin temperatures with greater body heat storage, (6) lesser ability to maintain circulating blood volume and (7) greater effects from dehydration. Because of these differences, it is even more essential for women than men that they be given adequate time for adaptation to thermal stress and, where possible, be provided appropriate environmental protection.