Physiological alterations in pulse rate during hot tub bathing in real-life settings and their associated factors

Abstract

【Background】

Bath-related deaths in Japan are expected to rise with the older population and exceed 27,000 per year. Understanding hemodynamic changes during hot tub bathing is crucial to avoid bath-related deaths. However, pulse rate changes during hot tub bathing in real-life settings among older adults, as well as the factors that influence them, remain poorly understood.

【Methods】

Thirty-three local residents (average age 68.5 years [standard deviation 7.7]) experienced the measurements of their bathroom temperature, hot tub water temperature, and pulse measured at 1-minute intervals for 17 days. A linear mixed-effects model was applied to evaluate the associations between water temperature and maximum pulse rate during hot tub bathing, as well as the association between hot tub bathing duration and maximum pulse rate. Adjustment variables included age, sex, body mass index, drinking habits, income, hypertension, living room temperature, and bathroom temperature.

【Results】

We confirmed 423 baths, while 109 baths with water temperatures of 41°C or above. Pulse rates were higher during hot tub bathing when the bathroom temperature was less than 16.5°C. In the adjusted model, a 1°C increase in water temperature and a 1-minute increase in hot tub bathing duration were associated with maximum pulse rates of 4.6 bpm (95% confidence interval [CI], 2.7-6.5) and 4.7 bpm (95% CI, 1.2-8.2), respectively.

【Conclusion】

This study showed the positive association of bathtub water temperature and duration of hot tub bathing with maximum pulse rate while hot tub bathing.