Training and acclimatization: effects on responses to exercise in a desert environment.

The purpose of this investigation was to observe differences in responses to work in a desert environment among males representing varying levels of acclimatization and physical training. Three groups of subjects were selected: 1) unacclimatized males (UM), VO2max = 46.8 ml . kg-1 . min-1, 2) acclimatized males (AM), VO2max = 49.6 ml . kg-1 . min-1, and 3) acclimatized-fit males (AFM) VO2max = 65.8 ml . kg-1 . min-1. Each subject sat for 40 min and then walked for 40 min at 3.5 miles/h on a grade which represented his 50% VO2max in a neutral indoor environment (WBGT = 18.1 DEGREES C) and in a desert (hot, dry and sunny) environment (WBGT = 29.9 DEGREES C). The UM experienced consistently higher HR during both rest and work in the heat than did the AM. The AFM exhibited lower HR than either AM or UM during both neutral and hot exposures, despite a higher workload. Both groups of acclimatized subjects possessed lower Tre's than the unacclimatized subjects in the heat. The superior fitness of the AFM gave an advantage in terms of increased sweating sensitivity since they had equal or greater SR at lower Tre. It was concluded that a high level of physical training is an additional and important variable in the ability to tolerate work in the desert.