A STUDY OF HEAT ACCLIMATIZATION, ITS DECAY AND REINDUCTION IN OBESE MALES

Nine fully acclimatized men falling in the lean, medium and obese categories of body composition were observed during four day heat exposure periods following acclimatization decay periods of various lengths in order to determine the effects of body composition on the decay and reinduction of acclimatization. The physiological variables taken in consideration were the inner body, or core, temperature, the Dubois mean skin temperature, the heart rate, the weight loss due to perspiration and the temperature differential between the core and the body shell, or surface. All of the men were subjected to an acclimatization schedule of twelve daily sessions which involved a bicycle pedalling task (50 watts) during 105 minutes of exposure at 105 F dry bulb and 45% humidity in order to insure that they were all fully acclimatized. Three decay, or non-exposure, periods of four, eight and twelve days were each followed by four days of reinduction. It was determined that body composition does not affect the rate of decay or reinduction of acclimatization, although this parameter as well as the extent of decay and the duration of the reinduction period does affect the physiological variables monitored in this study. Based on the results obtained, an acclimatization schedule similar to the two stage 6-12 schedule proposed by Wyndham (1954) is suggested for the obese worker. Furthermore, a cardiovascular surge occurring during the third day of the acclimatization and reinduction periods, and first reported by Wood and Bass (1960) was observed during this study. This particular phenomenon stresses the need to use a modified two stage acclimatization schedule to protect the overweight worker from unnecessary danger