Cardiovascular and Respiratory Responses to Muscular Activity during Immersion in Water at Different Temperatures

摘要

The thrust of this research program was to investigate muscular function during both sustained and intermittent isometric contractions as well as during rhythmic exercise carried out in air or during immersion of subjects to the neck in water at temperatures ranging from 15 C to 35 C. In one experiment the subjects were examined when they were completely under water. The limitations placed on muscular function in those varied circumstances may be related to the limits of flexibility of the cardiovascular and respiratory systems, to the temperature of the muscles and to the metabolic demands in aerobic, anaerobic and fatiguing exercise. Such events may place unexpected demands on both cardiovascular and respiratory function. Isometric exercise, either sustained or intermittent, was chosen to simulate carrying weights underwater, while bicycling, with the legs horizontal was chosen to approximate swimming. Studies were carried out to evaluate the changes that occur as a result of habituation to immersion in cold water. In addition, the mechanisms that compete for the local control of the circulation were examined during intermittent isometric contractions leading to muscular fatigue.