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The most important difference between summer and winter camping is the necessity, in winter, of maintaining warmth. For a short time before the winter camper turns in, a wood fire built on green poles laid on the snow, or the small gasoline cook stove in the tent, will make available some heat; but by and large, both on the trail and in camp, the human body must produce sufficient heat to maintain normal temperature. If the interior body temperature drops two degrees, intense shivering results, further lowering of temperature produces sluggishness and coma, and finally, at somewhere between 70° and 75°, death ensues. We must then consider the human body as a heat-producing machine and determine (1) what can be done to increase the amount of heat manufactured by the body, and (2) what can be done to conserve this heat. Production of body heat. —A normal male adult at rest, as in sleeping or loafing, liberates approximately 50 calories of heat per hour. This can be increased appreciably by eating or by exposure to cold. The only other means by which skiers may increase heat output is muscular action. Violent exercise will increase heat output as much as sixteen times. Shivering, which is merely a form of muscular action, will if intense, increase heat output several times; in fact, |
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