Acclimatization of older men to work in heat

¹ Department of Anatomy and Physiology, Indiana University, Bloomington, Indiana, University of Pittsburg, Pittsburgh, Pennsylvania, Army Medical Research and Nutrition Laboratory, Denver, Colorado, University of California, Berkeley, California, and Marquette University, Milwaukee, Wisconsin

Four men, ages 44–60, repeated daily work experiments in the heat by which they had demonstrated on themselves rapid acclimatization to work in a hot climate 21 years earlier. The work, heat stress, and duration of exposure were those originally found to cause marked hyperpyrexia and circulatory strain in unacclimatized men (mean age 31 years) on the 1st day in the heat. Under these conditions, the subjects sweated at 1.3– 1.5 kg/hr. Tolerance of the men on the 1st day of exposure was no less than when they were younger. Body temperatures and heart rates of the older men were lowered in successive days of exposure and the work was judged progressively easier. Final values of body temperature reached after 5–7 days of exposure were about the same as observed originally after the same number of exposures. Thus, these older men exhibited about the same degree of strain during work in the heat as they did 21 years earlier and acclimatized about as well.

Submitted on October 1, 1964

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