Cold tolerance of long-distance runners and swimmers in Hawaii

The purpose of this study was to measure thermal and metabolic responses of six marathon runners and six long-distance ocean swimmers during a standard cold tolerance test, and to compare the results. The two groups of lean endurance athletes lived in Hawaii and were matched on the basis of age, height, weight, and skinfold thickness. Maximal oxygen uptake, however, was significantly higher in the runners (66.5 versus 58.8 ml/(kg·min) for the swimmers). There were no significant differences in maximal tissue insulation or the derived nonfat insulation, although the runners tended to have higher values. Our findings suggest a possible hypothermic insulative adaptation in the runners and, therefore, indirectly support a recent hypothesis that marathon training may potentiate cross-adaptation to cold. Reasons for a relatively high nonfat insulation in the runners (0.098 (°C.m²)/W) are unknown, but seem related to a vascular mechanism.