Cold Acclimatization of Tropical Men during Short and Long Term Sojourn to Polar Environment

This study was undertaken to assess the status of cold acclimatization (CA) resulting from short- and long-term exposure of tropical men to severely cold environment of the Arctic and the Antarctic regions. Five Groups (seven each) of male subjects participated in this study. Cold-induced vasodilatation (CIVD) response was elicited during immersion of the right hand in cold water at 4 degree centigrade for 30 min at both the polar regions to evaluate peripheral CA. The 'standard cold test' at 10 degree centigrade for 2 hr was administered at the Arctic region on tropical and arctic residents and the data were compared with those for tropical men monitored at Delhi to ascertain the level of general CA. Group A (control) was studied at Delhi (29 degreeN, 77 degreeE) while Groups B and C were sailed to Antarctica (70 degreeS,11.5 degreeE). Their CIVD responses were monitored during thirteenth month and seventh to eighth week of stay, respective1y .There was no deliberate cold exposure, except during their 'occupation demand' outdoor duties. However, outdoor exposure for Group C was more. Group D was airlifted to the Arctic (70 degreeN, 38 degreeE) and studied during the seventh week of acclimatization. The subjects had regular deliberate cold exposure. For comparison, Group E of arctic residents was studied at the Arctic Group B did not show any adaptive modification to cold even after an year of sojourn in antarctic environment compared to Group A; while Group C subject, despite their short stay showed better CIVD response. Group D subjects recorded significant improvement in the response of general cold exposure as well as peripheral vascular response to local cold stress; their responses were comparable to those of the arctic residents (Group E). It is evident that human CA is impossible just by living in the coldest region of the globe even for prolonged periods. Deliberate regular exposure to atmospheric cold is the mandatory factor in developing human CA, the degree of which is related to the intensity of cold exposure