成人女性を対象とした生理・心理的評価に基づく足浴の最適な「水深」の検討

The Examination of the Optimal Depth of Water in a Foot-bath for Adult Women through Physiological and Psychological Evaluation

要旨

目的：成人女性を対象として足浴による生体反応を生理・心理学的な評価指標を用いて足浴の最適な「水深」を明らかにした．

方法：成人女性19名（21〜37歳）を対象に，座位にて41℃の湯温の足浴を15分間実施した．足浴の水深は三陰交を含まない8cm，三陰交を含み腓腹筋を含まない15cm，腓腹筋を含む20cmを設定し，1日おきに3種類の足浴を実施した．心拍変動から低周波成分（LF）と高周波成分（HF）を算出し，副交感神経活動をHF，交感神経活動をLF/HFとした自律神経活動，表面温，深部温，血圧を生理的指標とし，日本語版POMS-短縮版と新版STAIを心理的指標とした．

結果：POMSにおいては水深15cmでは6項目すべてのT得点において足浴前より足浴後の方が有意に低くなり，8cm・20cmに比較してよりリラックス効果が得られた．また，交感神経活動，副交感神経活動，心拍数，表面温，血圧においては水深の相違による有意差はみられなかった．深部温においては水深15cmが8cm・20cmに比較して有意に安定していた．

結論：成人女性を対象とした足浴の水深は生理・心理学的に8cm・20cmより15cmの方が最適であることが示唆された．

Aim: The purpose of this research is to determine the optimal depth of water in a foot-bath by analyzing adult women's physiological and psychological responses to foot bath.

Method: 19 adult women from 21 to 37 years-old were asked to put their legs in a bathtub containing water at 41 degrees Celsius in a sitting position for 15 minutes. We set up three types of foot-bathes with different depths—8cm, which was below the Sanyinjiao point, 15cm, which was above the Sanyinjiao point and below the gastrocnemius muscle, and 20cm, which was at the gastrocnemius muscle, and conducted each type of footh-bath every other day. Low frequency (LF) and high frequency (HF) was calculated from heart rate variability. Physiological indicators were measured by autonomic nerve activity (HF as parasympathetic nerve activity and LF/HF as sympathetic nerve activity), surface temperature, deep temperature, and blood pressure. Psychological indicators were measured by the Japanese version of the Profile of Mood States (POMS)-Brief Form and the new version of State-Trait Anxiety Inventory Form (STAI) JYZ.

Results: The POMS assessment showed that subjects were more relaxed when they took a footbath with 15cm depth of water than the ones with 8cm or 20cm depth of water at a statistically significant level. Yet, no statistically significant difference was found between three groups regarding sympathetic nerve, parasympathetic nerve, heart rate, surface temperature, and blood pressure. Deep temperature was more stable in 15cm depth of water than in 8cm and 20cm depth of water at a statistically significant level.

Conclusion: These results suggest that the optimal depth of water for adult women in a foot-bath is not 8cm/20cm but 15cm.