Relation of changing levels of physical fitness to human cold acclimatization

Abstract

Five nude Caucasian men were exposed for 1 hour to a temperature of 10° α 1°C in a cold chamber after normal activity, after physical training, and after bivouac in the interior of Alaska for 6 weeks during January and February. Body temperatures (hand, foot, trunk, skin, and rectal, recorded during exposure to acute cold, were the criteria by which the effects of the changing levels of physical training and the cold-acclimatizing encampment were compared and judged. After the program of physical training, but before the bivouac, skin and extremity temperatures were statistically higher than those recorded before training; no differences were noted after the bivouac, when the level of physical training remained unchanged and the only variable was exposure to cold. These data confirm an earlier suggestion that commonly accepted indices of acclimatization, (elevated skin temperatures) may also result from chronically elevated levels of physical activity. Additional evidence indicates the limitations of the bivouac or field exercises for 'cold exposure,' and suggests the questionable value of accepting physiological and thermal readjustments that occur during such programs as being indicative of the effects of cold. Submitted on July 5, 1960