Behavioural temperature regulation during a motor-toboggan traverse in Antarctica.

Ten men, members of the International Biomedical Expedition to the Antarctic (IBEA), regularly recorded their thermal comfort, clothing, and activity for 60 days while travelling by motor toboggan and living in tents on the Antarctic plateau. Air temperature averaged -14 degrees C (range +2 degrees to -29 degrees C) and wind speed 11 m s-1 (range 0 to 22 m s-1); on half the days there was wind-blown ("drift") snow. Almost 2,000 sets of observations, evenly distributed throughout the 12 h sampling period 0700 h to 1900 h, were made. Daily (24 h) energy expenditure averaged 14.6 MJ on travelling days, 12.7 MJ on days when men worked in camp, and 13.3 MJ for the whole traverse. Men were outdoors for 7.6 h of the 12 h sampling period on travel days and for 3.6 h on camp days. Bulky down-filled clothing, typical of that used by present-day polar expeditions, adequately protected the trunk from cold at the cost of overheating during exercise. Face, hands, and feet were less well protected, and they experienced cold-induced numbness and pain in 33%, 19%, and 12%, respectively, of the observations made in the coldest weather. Because men could not conveniently reduce clothing insulation to the extent required, sweating and discomfort from warmth increased with energy expenditure and were present in 60% of the observations made during heavy work. The results suggest that there is a need for improvements in clothing design which will permit a more complete adjustment to changes in activity. The residual cold stress might possibly have been enough to induce cold acclimatization, although the accompanying heat stress was probably insufficient to induce acclimatization to heat.