Acclimation to heat in the Antarctic

Abstract

Antarctic dwellers indicate that for a major portion of the time spent dog-sledging, there is no cold-stress. This chapter describes the thermal stress involved in dog-sledging in two ways: (1) directly, by intermittent monitoring of deep body temperature, and (2) indirectly, by measuring the sweating response of sledgers at different times during the year. Deep body temperatures were monitored using the temperature-sensitive radio pill designed by Wolff (1961). Calibration curves constructed for endoradiosonde were used to retrieve the gut temperatures. Sweating has been demonstrated to occur almost immediately upon initiation of voluntary activity, long before any changes in skin or deep body temperatures have occurred and therefore, a simple entrainment phenomenon may be cited as the cause of the increased sweat rates demonstrated in this work. The significant thermal stress undergone while sledging, plus the increase in sweat rates over the same period, must make the existence of a degree of acclimatization to heat extremely likely.