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Erschienen in:
01.11.2008 | Original Article
Sex-related differences in evaporative heat loss: the importance of metabolic heat production
Erschienen in: European Journal of Applied Physiology | Ausgabe 5/2008
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We evaluated the hypothesis that different rates of metabolic heat production between sexes, during exercise at the same percentage of maximum oxygen consumption \( \left( {\dot{V}{\text{O}}_{2\max } } \right), \) give proportional differences in evaporative heat loss. Seven males and seven females, exercised at 41.3 ± 2.7% \( \dot{V}{\text{O}}_{2\max } \) for 60-min at 40°C and 30% relative humidity. Whole-body direct air calorimetry measured rate of whole-body evaporative heat loss \( \left( {\dot{H}_{\text{E}} } \right), \) while metabolic heat production \( \left( {\dot{M} - \dot{W}} \right) \) was measured by indirect calorimetry. \( \dot{M} - \dot{W} \) was greater in males (243 ± 18 W m−2) relative to females (201 ± 4 W m−2) (P ≤ 0.05) throughout exercise. This was paralleled by a greater \( \dot{H}_{\text{E}} \) at end-exercise in males (207 ± 51 W m−2) relative to females (180 ± 3 W m−2) (P ≤ 0.05). Differences in metabolic heat production between sexes during exercise at a fixed percentage of \( \dot{V}{\text{O}}_{2\max } \) give differences in evaporative heat loss. To compare thermoregulatory function between sexes, differences in metabolic heat production must therefore be accounted for.