Effects of a Footbathing Intervention on Physiological, Endocrine, and Psychological Status in Japanese University Students: A Randomized Controlled Trial

Abstract

The present pilot study examined effectiveness of a 2-week footbathing intervention on physiological, endocrine, and psychological status in healthy Japanese university students. A total of 51 participants were randomly assigned to a footbathing or normal bathing group. Participants in both groups provided daily free descriptions of their physical and mental states during the intervention period. Participants also underwent measurements of autonomic nervous system activities and salivary cortisol, and completed questionnaires in the pre- and post-intervention periods, as well as in the follow-up period. Neither the footbathing group nor the normal bathing group showed significant changes in deep body temperature, blood pressure, or salivary cortisol through the intervention period. Significant increases in dispositional mindfulness and interoceptive awareness, and significant decrease in trait anxiety were observed regardless of the groups. Nevertheless, an awareness of changes in bodily sensations and mood by footbathing mentioned in the participants' free descriptions was significantly associated with increased deep body temperature, dispositional mindfulness, interoceptive awareness, and subjective well-being from the pre- to post-intervention periods. These results suggest that the period of intervention and sample size might have been insufficient to induce significant changes in baseline psychophysiological status, but that awareness of changes in psychophysiological states may potentially be involved in the mechanism of footbathing.

Keywords: autonomic nervous system activities; cortisol; footbathing; health; interoceptive awareness.

Figure 1

A flow diagram of participation.

Figure 2

Results from a correspondence analysis involving group as an external variable. Japanese characters within the figure show original Japanese words extracted from the participants’ free descriptions, i.e., “温かい (warm),” “効果 (effect),” etc. See Table 3 and the main text for correspondence between each Japanese word and its English equivalent.

Figure 3

Results from a co-occurrence network analysis for the footbathing group. Japanese characters within the figure show original Japanese words extracted from the participants’ free descriptions, i.e., “温かい (warm),” “効果 (effect),” etc. See Table 3 and the main text for correspondence between each Japanese word and its English equivalent.