Metabolic, Thermal and Cardiovascular Adjustments to Cold Exposure with Special Reference to Physical Work and Body Composition.

Oxygen consumption and rectal temperature (T sub re) were studied in 10 men and 8 women during 1 hr rest and exercise at 36W (8.2 kcal/min) in air and water at 20, 24, and 28 C. At rest, in all water conditions, the obese men ( 22% fat) maintained T sub re at levels similar to control values in air. During work, T sub re increased about 0.4 C under all conditions with essentially no difference in air and the three water temperatures. For average (15-18%) and ( 12%) men, T sub re decreased after 10-30 min rest at all water temperatures with the largest drop in T sub re (-1.4 C; 35.8 C) and increase in oxygen consumption (760 ml) observed for lean men in colder water. Exercise prevented the drop in T sub re in 24 and 28 C water for average men and 28 C water for lean men. For both groups, oxygen consumption was rapidly and significantly elevated when T sub re was reduced, with increases in oxygen inversely related to the fall in T sub re. Although the women possessed nearly twice the % fat as their lean and normal male counterparts, their fall in T sub re at rest was similar to the men at all water temperatures. Viewed somewhat differently, a female of 22% fat does not regulate T sub re when exposed to cold stress at rest as effectively as a male of similar percent fat. This difference in temperature regulation at rest may be partly explained by differences in thermogenesis between men and women in response to cold stress.
Prepared in cooperation with City Univ. of New York. Research Foundation.