Key result
Short-term warm water immersion significantly blunted cardiac baroreflex sensitivity gain from 2.9 to 1.8 ms/mmHg in healthy men.
Why the study?
Warm water immersion causes dizziness presumably due to a substantial drop in blood pressure, but its effects on cardiac baroreflex sensitivity and the contribution of arterial stiffness were unclear.
Does short-term warm water immersion reduce cardiac baroreflex sensitivity in healthy men?
Does short-term warm water immersion reduce cardiac baroreflex sensitivity in healthy men?
Absolute Event Rate: 1.8% vs 2.9%
p-value: p=0.005
Short-term warm water immersion acutely deteriorates cardiac baroreflex sensitivity, which may explain bathing-related dizziness and falls, particularly in individuals with stiffer arteries.
Warm water immersion (WWI) causes dizziness presumably due to a substantial drop of blood pressure. The aim of this study was to elucidate the effects of short-term WWI on cardiac baroreflex sensitivity (BRS) and the contribution of arterial stiffness to the cardiac BRS. Twelve apparent healthy men (44 ± 12 years) performed the single stand-up test after 5-min sitting in the bathtub without (Control) and with 41 °C warm water at the heart level (WWI). Cardiac BRS gain was evaluated by R-R interval response to the standing-induced drop of systolic blood pressure. In addition, before and 10 min after the single stand-up test, carotid arterial β-stiffness index was evaluated in the supine rest. BRS gain was blunted (2.9 ± 1.6 vs. 1.8 ± 1.1 ms/mmHg, P = 0.005), whereas β-stiffness index was not changed significantly after WWI. BRS gain correlated with β-stiffness index before (r = - 0.626, P = 0.028) and after WWI (r = - 0.672, P = 0.015). ANCOVA revealed that these slopes of linear regression lines remained unchanged after WWI (P = 0.350). These results indicate that a short-term WWI acutely deteriorates cardiac BRS. Individuals with stiffer arteries are relatively more susceptible to WWI because of their poor baseline BRS, which might be one of the causes of bathing-related falling in elderly persons as well as frailty.
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Sugawara et al. (2020) studied Healthy (n=12). Warm water immersion vs. Bathtub without water was evaluated on Cardiac baroreflex sensitivity (BRS) gain (p=0.005). Short-term warm water immersion significantly blunted cardiac baroreflex sensitivity gain from 2.9 to 1.8 ms/mmHg in healthy men.
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