Comparison of Cardiovascular and Psychological Responses to a 20-min Bath in Summer and Winter / 日本温泉気候物理医学会雑誌

ABSTRACT

  Background: This study aimed to clarify the effects of bathing on cardiovascular and psychological responses during winter and summer, focusing on three different time points (immediately after entering the bathtub, during bathing, and immediately after leaving the bathtub).   Methods: Ten young (29.6±1.5 years) individuals were asked to bathe for 20 min with 40°C hot water in summer and with 42°C hot water in winter. The room temperature and humidity in winter were 20.1°C and 56.7%, while those in summer were 27.0°C and 58.3%, respectively. Tympanic temperature (Tty) was measured using a thermistor thermometer; systolic blood pressure (SBP) and diastolic blood pressures (DBP) and heart rate (HR) were measured using an auto-sphygmomanometer, and double product (DP) was calculated using the value of HR multiplied by SBP value. Subjective thermal and comfortable sensations were evaluated using a seven-point rating scale.   Results: Results showed a significant increases in SBP values in both seasons immediately after bathing. In winter, DP increased significantly after bathing. Meanwhile, no significant differences were observed in all parameters immediately after bathing between winter and summer. On the contraly, significant differences were observed in Tty, HR, and DP value between winter and summer during bathing. HR and DP values in winter were significantly lower than those in summer immediately after leaving the bathtub. A relationship between thermal sensation and comfortable sensation was observed in both seasons, but the strength of the relationship was more relevant in summer than in winter.   Conclusion: The effects of bathing in 42°C hot water on the cardiovascular system in winter are greater than those in 40°C hot water in summer. The high temperature of the bath water may not produce as much discomfort during winter than that during summer, therefore bathing time may be longer.