SEXUAL VARIATIONS IN THERMOREGULATION DURING HEAT-STRESS

  • 1 January 1978
    • journal article
    • research article
    • Vol. 49  (5) , 715-719
Abstract
Four male and 3 female physically fit, but untrained subjects performed a treadmill walking task in neutral (25.degree. C), warm (32.degree. C) and hot (40.degree. C) environments. The treadmill grade for each subject was based on 50% .ovrhdot.VO2 max [maximal O2 uptake] as determined in a neutral environment. Environmental exposures were 2 h in duration divided into 40 min of rest, work and recovery. No distinct sexual differences in rectal and skin temperature responses were observed in the 3 environments. The male subjects had higher heart rates and greater evaporative weight losses during exercise in all environments; the female subjects experienced less severe increases in metabolic requirements during work in the warm and hot environments than the male subjects. The greater percentage of increase in heart rates relative to changes in the metabolic cost of work in the females suggested a greater cardiovascular component of thermal regulation in the female than in the male subjects. Physically fit females are apparently capable of working in the heat about as well as males when work load is relative to individual maximal aerobic capacity.