Human physiological responses to immersion into water of different temperatures

Abstract

To differentiate between the effect of cold and hydrostatic pressure on hormone and cardiovascular functions of man, a group of young men was examined during 1-h head-out immersions in water of different temperatures (32 degrees C, 20 degrees C and 14 degrees C). Immersion in water at 32 degrees C did not change rectal temperature and metabolic rate, but lowered heart rate (by 15%) and systolic and diastolic blood pressures (by 11 %, or 12%, respectively), compared to controls at ambient air temperature. Plasma renin activity, plasma cortisol and aldosterone concentrations were also lowered (by 46%, 34%, and 17%, respectively), while diuresis was increased by 107%. Immersion at 20 degrees C induced a similar decrease in plasma renin activity, heart rate and systolic and diastolic blood pressures as immersion at thermoneutrality, in spite of lowered rectal temperature and an increased metabolic rate by 93%. Plasma cortisol concentrations tended to decrease, while plasma aldosterone concentration was unchanged. Diuresis was increased by 89%. No significant differences in changes in diuresis, plasma renin activity and aldosterone concentration compared to subjects immersed to 32 degrees C were observed. Cold water immersion (14 degrees C) lowered rectal temperature and increased metabolic rate (by 350%), heart rate and systolic and diastolic blood pressure (by 5%, 7%, and 8%, respectively). Plasma noradrenaline and dopamine concentrations were increased by 530% and by 250% respectively, while diuresis increased by 163% (more than at 32 degrees C). Plasma aldosterone concentrations increased by 23%. Plasma renin activity was reduced as during immersion in water at the highest temperature. Cortisol concentrations tended to decrease. Plasma adrenaline concentrations remained unchanged. Changes in plasma renin activity were not related to changes in aldosterone concentrations. Immersion in water of different temperatures did not increase blood concentrations of cortisol. There was no correlation between changes in rectal temperature and changes in hormone production. Our data supported the hypothesis that physiological changes induced by water immersion are mediated by humoral control mechanisms, while responses induced by cold are mainly due to increased activity of the sympathetic nervous system.

Dominance in cardiac parasympathetic activity during real recreational SCUBA diving

“…During SCUBA diving, facial temperature receptors may have contributed to vagal activation. In the present study, the exposure time to the cold water may have contributed to the increase in parasympathetic activity, the decrease in cardiac sympathetic activity and Wnally, to an increase in mean RR (Srámek et al 2000). Previous hyperbaric chamber experiments have demonstrated an enhancement of parasympathetic activity, this autonomic disequilibrium appearing independently of modiWcations in respiratory frequency (Lund et al 2000).…”

Physikalische Therapie: Therapiemittel Wasser (2)

“…Der Auftrieb wird unmittelbar für Bewegungsübungen genutzt [2]. Srámek et al [3] fanden in ihrer Studie an gesunden, freiwillig teilnehmenden jungen Männern die Hypothese bestätigt, dass die Veränderung physiologischer Parameter wie Blutdruck und Herzfrequenz beim Eintauchen in Wasser hormonell gesteuert werden, im Unterschied zum Einfluss der Kälte, die den Sympathikotonus erhöht [3]. …”

Scientific evidence-based effects of hydrotherapy on various systems of the body

“…Along with HR and blood pressure (BP), the plasma renin activity, plasma cortisol, and aldosterone concentrations were also lowered by 46%, 34%, and 17%, respectively, while diuresis was increased by 107%. [3]…”

“…No significant differences in changes in plasma renin activity, aldosterone concentration, and diuresis compared with subjects immersed in 32°C. [3]…”

“…The physiological changes induced by WI are mediated by humoral control mechanisms, while responses induced by cold are mainly due to increased activity of the sympathetic nervous system (SNS). [3]…”