In Shackleton's trails: Central and local thermoadaptive modifications to cold and hypoxia after a man-hauling expedition on the Antarctic Plateau

摘要

Cold and hypoxia constitute the main environmental stressors encountered on the Antarctic Plateau. Hence, we examined whether central and/or peripheral acclimatisation to the combined stressors of cold and hypoxia would be developed in four men following an 11-day man-hauling expedition on this polar region. Before and after the journey, participants performed a static whole-body immersion in 21 degrees C water, during which they were breathing a hypoxic gas (partial pressure of inspired 02: 97 mmHg). To evaluate their local responses to cold, participants also immersed the hand into 8 degrees C water for 30 min, while they were whole-body immersed and mildly hypothermic [i.e. 0.5 degrees C fall in rectal temperature (T-rec) from individual pre-immersion values]. T-rec, and aldn temperature (T-ak), skin blood flux, and oxygen uptake (reflecting shivering thermogenesis) were monitored throughout. The polar expedition accelerated by similar to 14 min the drop in Trr, [final mean (95% confidence interval) changes in T-rec: Before = -0.94 (0.15) degrees C, After: 1.17 (0.23) degrees C]. The shivering onset threshold [Before: 19 (22) min, After: 25 (19) min] and gain [Before: 4.19 (3.95) mL min(-1) kg, After: 1.70 (1.21) mi. min(-1) kg(-1)] were suppressed by the expedition. TA did not differ between trials. The development of a greater post expedition hypothermic state did not compromise finger circulation during the hand-cooling phase. Present findings indicate therefore that a hypothermic pattern of cold acclimatisation, as investigated in hypoxia, was developed following a short-term expedition on the South Polar Plateau; an adaptive response that is characterised mainly by suppressed shivering thermogenesis, and partly by blunted cutaneous vasoconstriction.