Impact of Water Temperature on Heart Rate Variability during Bathing

Abstract

Background: Heart rate variability (HRV) is affected by many factors. This paper aims to explore the impact of water temperature (WT) on HRV during bathing. Methods: The bathtub WT was preset at three conditions: i.e., low WT (36–38 °C), medium WT (38–40 °C), and high WT (40–42 °C), respectively. Ten subjects participated in the data collection. Each subject collected five electrocardiogram (ECG) recordings at each preset bathtub WT condition. Each recording was 18 min long with a sampling rate of 200 Hz. In total, 150 ECG recordings and 150 WT recordings were collected. Twenty HRV features were calculated using 1-min ECG segments each time. The k-means clustering analysis method was used to analyze the rough trends based on the preset WT. Analyses of the significant differences were performed using the multivariate analysis of variance of t-tests, and the mean and standard deviation (SD) of each HRV feature based on the WT were calculated. Results: The statistics show that with increasing WT, 11 HRV features are significantly (p < 0.05) and monotonously reduced, four HRV features are significantly (p < 0.05) and monotonously rising, two HRV features are rising first and then reduced, two HRV features (fuzzy and approximate entropy) are almost unchanged, and vLF power is rising. Conclusion: The WT has an important impact on HRV during bathing. The findings in the present work reveal an important physiological factor that affects the dynamic changes of HRV and contribute to better quantitative analyses of HRV in future research works.

Bathtub ECG as a Potential Alternative to Light Stress Test in Daily Life

“…Mizukami et al confirmed that a bathtub ECG is a suitable method to follow up those patients with a pacemaker implanted [15]. Xu et al confirmed that heart rate variability (HRV) using a bathtub ECG is impacted by water temperature during bathing [16]. In our previous study, a stress index (SI) was calculated to evaluate daily stress using a bathtub ECG and using a convolutional neural network personal identification with a bathtub ECG [17,18].…”

“…In previous studies, the impact of different water temperatures on HRV during bathing was examined and confirmed. With the increase in water temperature, some HRV features displayed different degrees of impact, such as decrease or increase [16,27,28]. In daily practice, the water temperature mostly is set between 38 • C and 42 • C during bathing [29].…”

Recent Trends in Computational Biomedical Research

“…The paper with the title "Impact of Water Temperature on Heart Rate Variability during Bathing" aims to explore the impact of water temperature (WT) on Heart Rate Variability (HRV) by collecting five electrocardiogram (ECG) recordings of each of 10 subjects at different preset bathtub WT conditions during bathing [7]. Based on statistical analysis, it has been shown that the WT has an important impact on HRV during bathing.…”