Climatic stress in the workplace: its effect on thermoregulatory responses and muscle fatigue in female workers.

The present study was designed to determine the differences in thermoregulatory responses and the levels of muscle fatigue in the seated worker, performing a task involving a light metabolic load (typing), versus the standing worker, undertaking a task of a heavier metabolic load (lifting), in different climatic conditions (neutral and hot, humid). The results showed that environmental heat significantly influenced the cardiovascular and thermoregulatory systems in workers performing both light and heavy work tasks. In addition, environmental heat was shown to influence the magnitude of the frequency shift during the fatiguing muscle contraction in the typists rather than the lifters. These results suggest that: (1) performance of even sedentary workers performing a light manual task may be deleteriously affected by environmental heat; and (2) environmental heat may be of secondary importance to the nature of the task investigated on the level of muscle fatigue.