Effects of half-body and foot baths on peripheral circulation in healthy adult males: a pilot study

[Purpose] This study aimed to clarify the optimal conditions of warm-water bathing required to improve peripheral circulation. [Participants and Methods] Ten healthy males experienced three warm-water bathing depths (half-body, low-leg, and foot) on different days. Peripheral circulation (earlobe blood flow), tympanic temperature, pulse rate, and blood pressure were measured during each session and compared among the bathing conditions. [Results] In half-body bathing, the relative blood flow of participants increased steeply to a level 2.7-fold higher than the baseline during bathing and rapidly decreased after that. Conversely, the relative blood flow gradually and continuously increased to a level 1.7-fold higher than that at the baseline during low-leg bathing and maintained a similar level after that. The blood flow did not markedly change throughout the experiment in foot bathing. The pulse rate during foot bathing and that during low-leg bathing did not change throughout the observation period, but that of half-body bathing increased considerably. [Conclusion] Rapid changes in pulse rate or blood pressure associated with bathing are considered risky. We suggest that low-leg bathing, rather than the usually adopted half-body bathing, is appropriate for improving peripheral circulation in terms of effectiveness and safety.