Responses of Unacclimatized Men Under Stress of Heat and Work

Abstract

When measured after 1 hr, of rest before each expt. and also during exposure to heat and exercise, rectal temps. of unacclimatized Africans were uniformly higher, namely 1.3[degree]F, than were those of acclimatized Africans. The difference in rectal temp. was no greater when the men were under severe heat stress, such as light work in air at 96[degree] F wet bulb temp., than under mild heat stress, 84[degree]F wet bulb temp. Therefore, if one chooses an arbitrary limit of rectal temp. for safety, say 102 [degree]F, unacclimatized men reach this level at lower wet-bulb temps., approx. 3-6 deg. F, than the acclimatized men. This can be regarded as a measure of the benefit of acclimatization. The reason is that if an environment requires, say 1.0 1. of sweat/4 hrs. for the maintenance of thermal equilibrium, then acclimatized men can produce this quantity at a rectal temp. of 100.0[degree] F whereas unacclimatized men require a rectal temp. of 101.6[degree]F for the same effect.