Use of sweating rate to predict other physiological responses to heat.

Abstract

Two acclimatized male subjects were exposed to graded combinations of exercise and environmental temperature to determine whether physiological cost, in terms of rectal temperature (Tr) and heart rate (HR), is different per kcal of exercise metabolism (M) and per kcal of heat stress from the environment (HS). Data of Robinson on 4 subjects exposed under a variety of conditions were examined in the same way. The effect of a unit of M on HR in the 6 subjects was about twice as great as the effect of a unit of HS, but the effect of a unit of M on Tr was not significantly different from the effect of a unit of HS. In 30 combinations tried on 1 subject cardiac output was found to increase by different amounts for equal amounts of M and HS. This suggests that no 2 combinations of M and HS elicit the same combination of HR, cardiac output and Tr.