An Initial Investigation of Heart Rate Variability (HRV) Related to Foot Bathing Water Temperature and Vibration Relaxation for Elderly People

This study explores the effects of foot bathing on relaxation in elderly individuals, utilizing heart rate variability (HRV) analysis and participant surveys. The subjects comprised seven participants aged between 71 and 90, who experienced foot baths under 40 ℃ and 30 ℃, with both still and vibrating water. HRV indicators, including frequency domain and time series analysis, were used to assess the activities of the sympathetic and parasympathetic nervous systems. Surveys evaluated comfort levels under different water temperature and vibration conditions. The study results indicate that each participant had different preferences for water temperature and the presence of vibrations. Responses to the subjective questionnaire generally suggested that participants found 40 ℃ vibrating water to be the most comfortable. The objective HRV data supported these findings, showing significant agreement with the subjective reports. For example, participants demonstrated nearly identical levels of relaxation in both dynamic and still water conditions based on both subjective and objective measures. Moreover, more than half of the participants’ subjective temperature preferences aligned with the HRV data, providing further validation of the findings. It is recommended to conduct larger-scale studies to confirm these findings and explore additional physiological and psychological indicators.