Effect of neutral douche on autonomic variables in normal healthy individuals: A randomized controlled trial

Neutral Douche and Autonomic Function in Healthy Adults

Abstract

Neutral douche or hydrotherapy modality using water of neutral temperature is widely used to induce relaxation and promote autonomic equilibrium. Despite its widespread clinical use, the autonomic physiological responses to neutral douche remain insufficiently characterized in controlled settings. Therefore, this study aimed to evaluate the impact of neutral douche on autonomic outcomes in healthy individuals. In a randomized controlled trial, 60 healthy volunteers aged 17-35 were randomly assigned to the experimental neutral douche group (n=30) or the control group (n=30), which underwent standing rest for 20 min without hydrotherapy exposure. The intervention consisted of a general body douche at 35°C-37°C for 20 min, while the control group stood in the same environment without receiving the treatment. Measurements of heart rate, blood pressure, respiratory rate, and heart rate variability (HRV) were taken pre- and post-intervention. Exposure to neutral douche resulted in a significant reduction in heart rate (p<0.01) as well as a prolongation of mean RR intervals, indicating that the neutral douche may enhance parasympathetic activity. The HRV analysis from this group also suggested that there was a significant decrease in low frequency power (p<0.01), and a significant increase in high frequency power (p<0.01), suggesting that neutral douche could prevail in parasympathetic dominance. Interestingly, the neutral douche group experienced a significant decrease in HR, while systolic blood pressure and diastolic blood pressure significantly increased (p<0.05). The increase in BP may be related to baroreflex regulation or the possible physical effects of the water perfusion pressure. Collectively, the findings suggest that neutral douche facilitates parasympathetic activity and alters blood pressure, potentially benefiting those with autonomic dysfunction or sympathetic dominance. Further research is needed to explore its therapeutic applications and long-term effects.