Autonomic Nervous System, Cardiovascular and Circulatory Effects of Cool, Neutral and Warm Water Immersion
Hildenbrand, Kasee J.
Becker, Bruce E.
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Purpose: Numerous studies have been conducted looking at the effects of water immersion temperatures on the cardiovascular system, but very little work has been done regarding the effects of immersion temperature on factors relating to autonomic nervous system regulation. The purpose of this study is to examine several variables relating to the autonomic nervous system effects upon cardioregulation while immersed in cool (88 F), neutral (98 F) and warm (102 F) water. Methods: Sixteen (16) college-age subjects volunteered to be a part of this research study. Subjects completed the study session in one day by sitting in each of the three tubs while being monitored by the Biopac system monitors and Coretemp radiofrequency measurement of core temperature. The study protocol initiated with the subject sitting at poolside, followed by immersion in cool, neutral and warm water with 12 minute rest periods in between immersions. Results: In this population, there appears to be a very significant effect of warm water immersion upon the autonomic nervous system. The changes noted were quite consistent across all of the subjects tested in the study. Heart rates rose during the warm water immersion period, but not during the cool or neutral immersion periods, whereas blood pressures remained quite constant throughout. Conclusions: The data we have analyzed so far indicates that there are a number of important physiologic changes that occur during war water immersion, producing increased sympatho-vagal balance, slight blood pressure drop and slight increase in heart rate, with a dramatic increase in distal superficial circulation. These changes may have health implications for warm water immersion.