EXCHANGES OF HEAT AND TOLERANCES TO COLD IN MEN EXPOSED TO OUTDOOR WEATHER

Abstract

Men nearly nude were exposed outdoors to environments ranging from uncomfortably warm to bitterly cold for periods of 1-4 hrs. Surface temps. were proportioned to air temps. between 33 [degree] and 88[degree]F. Trunk surface temps. might be 30[degree]F. cooler than the rectum, indicating maintenance of an enormous internal insulation. The thickness of this insulation is estimated at 3-5 cms. O2 consumption while shivering was augmented as much as 5 fold of that while not shivering. Shivering produced muscular fatigue within 2 or 3 hrs. Men doing hard work sometimes shivered also. The blood became markedly concentrated and diuresis of chill often resulted. Heat exchanges are fractionated both for men at rest and for men working at an arbitrarily chosen intensity, throughout the range of air temps. Men lost 700 Calories during the 1st hr. of exposure in air at 33[degree]F. while producing 300 Calories. Full sunshine saved 90 Calories/hr. of heat production; wind of quadrupled velocity augmented loss by an equal amt.