Effects of Hand Bathing at Different Water Temperatures on Autonomic Nervous Activity

Abstract

Purpose: This study aimed to clarify the effects of hand baths at commonly used water temperatures on autonomic nervous activity in daily life.

Methods: The subjects were 15 healthy female volunteers. We experimentally induced states of predominant sympathetic nervous activity and predominant parasympathetic nervous activity, setting two hand bath temperatures at 39°C and 42°C. We performed a total of four types of experiments, each lasting 3 minutes.

Results: During sympathetic nerve activation induced by mental arithmetic loading, the sympathetic activity index at 39°C was 1.31 (0.77–1.70), and at 42°C it was significantly higher at 2.09 (1.17–2.50). During parasympathetic nerve activation induced by eye closure, the sympathetic activity index at 39°C was 0.13 (0.01–0.36), and at 42°C it was significantly higher at 0.44 (0.21–0.66).

Conclusions: The study has revealed that a water temperature of 42°C stimulates the sympathetic nervous system more effectively than a temperature of 39°C, both during sympathetic and parasympathetic nerve activation. Furthermore, the findings indicate that adjusting the water temperature based on the desired outcome, whether for relaxation or arousal, can lead to more effective care.