The Effects of Footbath Therapy Proved with Physiology Parameters, including Meridian Energy for Health Promotion ^†

Abstract

Footbath therapy is effective for health and wellness. We compared the effects of hot water footbaths (HFB), contrast water footbaths (CFB), and warm water footbaths (WFB) using physiological parameters, including blood pressure, calf volume, flexibility, and meridian energy for six weeks. Significant differences in diastolic blood pressure and calf volume were observed from the third to fifth week, and CFB showed the best effect. CFB and WFB demonstrated improvements in meridian energy, while HFB had no effect. These findings highlighted the effectiveness of CFB in managing stress and promoting health and well-being.

1. Introduction

Hydrotherapy has been used in medical fields for pain reduction, the improvement of joint mobility and muscle strength, enhancement of heart efficiency, promotion of blood and lymph circulation, and improvement of metabolic function, skin condition, and muscle control and coordination [1]. Although contrast bath therapy is beneficial for sports injuries, joint pain, muscle fatigue, inflammation, and poor blood circulation [2], its application is limited due to the need for specialized equipment and professional instructors. Kneipp’s foot-treading method originated in Europe enhances blood circulation, reduces foot swelling and fatigue, and improves joint mobility [3]. Footbath therapy, especially with hot water, has also been proven to be effective in promoting health and wellness by alleviating symptoms of pain, fatigue, and insomnia, improving circulation, and enhancing overall well-being [4].

Foot health is essential to overall physical health, as foot blood circulation is closely linked to systemic blood circulation and metabolism, thereby promoting the regulation function of the nervous and endocrine systems [5]. Studies have shown that footbaths relieve fatigue and improve sleep quality in stroke and cancer patients, regulate heart rate variability [6], increase core body temperature, relieve menstrual pain and maternal anxiety, and restore low-meridian energy, among other health benefits [4,5,6,7,8]. A previous study revealed that occupational stress was a significant factor in high-stress industries such as high-tech and banking industries in Taiwan [9]. Strategies to overcome occupational stress include promoting work–life balance, creating a positive work environment, and providing necessary resources [10]. However, there is a dearth of simple and practical health promotion and guidance methods that can be easily used in daily life. Furthermore, limited research has been conducted to compare the effects of footbath in different temperatures on physiological parameters. Thus, this study was conducted to compare the effects of the hot water footbath and contrast water footbath on health promotion with warm water footbath as the control group. The study result provided evidence-based guidance on the use of footbath therapy as a health promotion strategy.

2. Materials and Methods

2.1. Subjects

This study was conducted with the approval of the Institutional Review Board (IRB: 103075). The participants were recruited from Chia Nan University of Pharmacy and Science, and were between the ages of 20 and 25. Volunteers were required to complete a health assessment form (Brief Symptom Rating Scale, BSRS-5) and a brief physical examination. Those who passed the screening then signed a consent form. A total of 33 participants were enrolled and allocated into three groups based on their decreasing body mass index (BMI) in a sequential order. Before the study, each group consisted of 11 participants. Five participants could not complete the experiment. Thus, the warm water footbath group (WFB, n = 9), hot water footbath group (HFB, n = 9), and contrast footbath group (CFB, n = 10) were included in the study. During the study, the participants’ lifestyles were recorded, but they were subjected to no restrictions in their lives.

2.2. Methods

The study was conducted as a single-blind trial with participants undergoing a 15 min footbath once a week for six consecutive weeks at a room temperature of 25 ± 2 °C. Based on other research [2], water temperatures were set to 10 °C for cold water, 30 °C for warm water, and 40 °C for hot water. Skin electrical conductance was measured for psychological stress, while meridian energy was measured using the ARDK^® on 24 special acupoints in the wrists and ankles. Most of the acupoints selected were the originating acupoints of the 12 meridians, namely the lung, large intestine, stomach, spleen, heart, small intestine, urinary bladder, kidney, pericardium, triple burner, gallbladder, and liver meridians [11]. Calf volume was measured using Archimedes’ volume measurement bucket, and blood pressure and flexibility were measured using devices. All data were collected before and after a footbath for six weeks. The data were analyzed using inferential statistics such as ANOVA and paired t-tests with a significance level set at p < 0.05.

3. Results

3.1. BSRS-5 Scale

A total of 33 participants joined in a 3-month lifestyle assessment for the evaluation of their sleep, mood, disease, and medication conditions. The participants were 22.21 ± 1.36 years old, including nine males (27.3%) and 24 females (72.7%). The mean Body Mass Index (BMI) was 22.77 ± 4.38 kg/m². Among the participants, 30 (90.9%) had no smoking habit, one (3.0%) had an occasional smoking habit, and two (6.1%) had a social smoking habit. In total, 23 (69.7%) had no drinking habit, seven (21.2%) had an occasional drinking habit, and three (9.1%) had a social drinking habit. A total of 15 (45.5%) had no habit of drinking coffee, one (3.0%) drank coffee daily, and 17 (51.5%) drank coffee occasionally. A total of 12 (36.4%) had no habit of drinking tea, six (18.2%) drank tea daily, and 15 (45.5%) drank tea occasionally. Of the participants, 19 (57.6%) had a mostly sedentary lifestyle, while 14 (42.4%) did not. Before the experiment, participants underwent medical and foot-related condition assessments, and those with significant medical conditions were excluded. However, in the medical history assessment, one participant had a history of asthma, but since the condition had not occurred in the past 6 months, the participant was still eligible to participate in the study. The participants were assessed using the Brief Symptom Rating Scale 5 (BSRS-5), and all participants had BSRS-5 scores less than 10, indicating a good daily living status (

Table 1. BSRS-5 assessment results.

	Groups	Total (n = 33)	Footbath Groups
Score			WFB (n = 11)	HFB (n = 11)	CFB (n = 11)
0–5		24 (72.7%)	9 (81.8%)	7 (63.6%)	8 (76.7%)
6–9		9 (27.3%)	2 (18.2%)	4 (36.4%)	3 (27.3%)
0–14		0	0	0	0
15–24		0	0	0	0

Note: BSRS (Brief Symptom Rating Scale), WFB (warm water footbath), HFB (hot water footbath), CFB (contrast water footbath), n = participants.

). During the experiment, five participants terminated their participation due to personal reasons, resulting in a final sample size of 28.

3.2. Evaluation of Physiological Parameters

We investigated the effect of footbath therapy on physiological parameters such as blood pressure, calf volume, and flexibility. The results of the three different foot bath groups were evaluated and compared.

The results indicated that the WFB group showed a statistically significant decrease in systolic blood pressure (SBP) by 8.33 mmHg before intervention (w0) to the end of the experiment (W7). The significant effect on SBP was observed from the third week of the experiment, while the effect on diastolic blood pressure (DBP) was minimal. However, the HFB and CFB groups did not show significant differences in SBP and DBP. ANOVA analysis was conducted to compare the values among the three groups and statistical differences in DBP were observed, but not SBP. The changes in DBP showed significant differences among the groups in the third week (p = 0.001), fourth week (p = 0.031), and fifth week (p = 0.007). The Tukey HSD test revealed that the CFB group had the most significant impact on DBP, followed by the WFB group and the HFB group. There were no long-term differences in SBP and DBP changes among the groups after the 6-week intervention (

Table 2. Changes in blood pressure of three different groups after footbath three different groups.

Parameters Week			WFB (n = 9)	HFB (n = 9)	CFB (n = 10)	p-Value (Tukey HSD)
SBP	Original	Before (w0)	109.89 ± 10.914	104.56 ± 3.408	110.30 ± 13.549
		After (w7)	101.56 ± 12.084 #	104.67 ± 3.575	103.70 ± 2.813
	Net value	w1	−8.33 ± 5.657	0.11 ± 10.541	−3.90 ± 13.085	0.244
		w2	−1.00 ± 10.112	−4.11 ± 4.936	−4.00 ± 8.300	0.651
		w3	−2.33 ± 5.050 #	−4.11 ± 10.043	−2.40 ± 6.381	0.846
		w4	−4.56 ± 7.955	0.44 ± 5.981	−3.80 ± 6.596	0.267
		w5	0.56 ± 10.370 #	−1.56 ± 5.833	−4.20 ± 6.546	0.423
		w6	−1.67 ± 5.315 #	−3.20 ± 23.734	−3.30 ± 6.800	0.774
DBP	Original	Before (w0)	64.67 ± 6.856	59.78 ± 6.741	64.50 ± 8.059
		After (w7)	60.89 ± 10.006	59.78 ± 6.037	63.10 ± 6.437
	Net value	w1	−4.00 ± 5.979	0.00 ± 5.148	−0.90 ± 7.666	0.392
		w2	−0.78 ± 4.893	0.22 ± 4.086	−1.30 ± 6.165	0.812
		w3	0.78 ± 3.598	1.44 ± 3.468	−6.00 ± 3.801	0.001 * (a, c)
		w4	−3.78 ± 2.539	1.44 ± 4.503	−5.50 ± 7.764	0.031 * (c)
		w5	2.22 ± 6.320	1.78 ± 2.774	−4.90 ± 5.301	0.007 * (a, c)
		w6	−0.33 ± 5.099	−2.56 ± 4.447	−3.60 ± 5.317	0.365

Note: SBP (systolic blood pressure), DBP (diastolic blood pressure), WFB (warm water footbath), HFB (hot water footbath), CFB (contrast water footbath), w = weeks, n = participants, data presented M ± SD, significant: p < 0.05, * = ANOVA, ^a = WFB/CFB, ^c = HFB/CFB; ^# = pair t-test.

).

Table 3. Changes in calf volume and flexibility changes in three different groups after footbath.

Parameters Week			WFB (n = 9)	HFB (n = 9)	CFB (n = 10)	p-Value (Tukey HSD)
Calf volume	Original	Before (w0)	24.40 ± 0.919	24.70 ± 0.750	24.68 ± 0.978
		After (w7)	24.41 ± 0.929	24.81 ± 0.720 #	24.62 ± 1.009
	Net value	w1	0.01 ± 0.105	0.11 ± 0.127	−0.06 ± 0.084	0.007 * (c)
		w2	0.04 ± 0.073	0.17 ± 0.068	−0.05 ± 0.071	0.000 * (a, b, c)
		w3	0.00 ± 0.071	0.16 ± 0.053	−0.01 ± 0.137	0.003 * (b, c)
		w4	0.03 ± 0.071	0.13 ± 0.087	−0.04 ± 0.070	0.000 * (b, c)
		w5	0.06 ± 0.073	0.11 ± 0.060	−0.06 ± 0.070	0.000 * (a, c)
		w6	−0.04 ± 0.088	0.12 ± 0.044	−0.09 ± 0.057	0.000 * (b, c)
Flexibility	Original	Before (w0)	28.39 ± 10.68	30.31 ± 9.726	29.06 ± 2.695
		After (w7)	29.89 ± 11.75	31.83 ± 9.253 #	31.33 ± 2.409 #
	Net value	w1	1.50 ± 2.194	1.52 ± 1.502	1.95 ± 2.692	0.881
		w2	1.61 ± 2.082	2.76 ± 2.017	0.57 ± 2.045	0.075
		w3	1.43 ± 1.097	2.56 ± 2.481	1.18 ± 2.124	0.304
		w4	1.48 ± 1.766	1.72 ± 1.161	1.72 ± 2.566	0.954
		w5	2.68 ± 1.663	2.46 ± 1.711	1.75 ± 0.951	0.365
		w6	1.72 ± 2.041	2.64 ± 1.816	1.19 ± 1.863	0.266

Note: SBP (Systolic blood pressure), DBP (Diastolic blood pressure), WFB (warm water footbath), HFB (hot water footbath), CFB (contrast water footbath), w = weeks, n = participants, data presented M ± SD, significant: p < 0.05, * = ANOVA, ^a = WFB/CFB, ^b = WFB/HFB, ^c = HFB/CFB; ^# = pair t-test.

shows significant differences between the groups in calf volume. Specifically, the CFB group had a significant reduction in calf volume from the first to the sixth week of intervention. The three groups revealed a significant decrease in calf volume. Post hoc tests showed that the decrease of the CFB group was larger than that of the WFB group and the HFB group. Although no statistically significant differences were found in flexibility among the three groups, significant differences were observed in the long-term follow-up results of the groups of CFB and HFB in paired t-tests between the beginning (W0) and end (W7) of the experiment.

3.3. Meridian Energy

Table 4. Changes in meridian energy between three different groups after footbath.

Parameters Week			WFB (n = 9)	HFB (n = 9)	CFB (n = 10)	p-Value (Tukey HSD)
Total energy	Original	Before (w0)	15.00 ± 14.697	21.78 ± 18.747	25.30 ± 21.618
		After (w7)	33.44 ± 19.456 #	34.33 ± 20.512	38.50 ± 25.439
	Net value	w1	16.67 ± 21.500	8.67 ± 28.688	13.20 ± 29.698	0.821
		w2	12.11 ± 14.146	−0.44 ± 22.973	15.60 ± 23.372	0.234
		w3	27.89 ± 18.210	−8.33 ± 14.009	4.20 ± 13.464	0.000 * (a, b)
		w4	2.11 ± 13.569	−3.67 ± 18.682	20.10 ± 26.780	0.048 * (c)
		w5	3.44 ± 26.302	−7.22 ± 21.022	16.30 ± 31.305	0.179
		w6	1.67 ± 15.588 #	−6.89 ± 24.670	−0.50 ± 31.529	0.755
systemic report	Original	Before (w0)	48.67 ± 12.845	50.78 ± 14.856	44.50 ± 13.385
		After (w7)	57.33 ± 10.283	50.33 ± 8.426	52.30 ± 16.667
	Net value	w1	6.11 ± 12.057	−1.33 ± 15.788	7.80 ± 10.075	0.279
		w2	4.44 ± 9.606	−3.22 ± 16.076	7.50 ± 16.009	0.267
		w3	13.89 ± 13.896	−3.89 ± 13.014	2.30 ± 18.172	0.061
		w4	5.89 ± 5.487	−4.78 ± 11.987	11.50 ± 12.572	0.009 * (c)
		w5	8.33 ± 13.153	−2.89 ± 8.054	5.00 ± 14.103	0.152
		w6	2.22 ± 8.913	−5.67 ± 9.138	5.80 ± 11.755	0.06

Note: WFB (warm water footbath), HFB (hot water footbath), CFB (contrast water footbath), w = weeks, n = participants, data presented M ± SD, significant: p < 0.05, * = ANOVA, ^a = WFB/CFB, ^b = WFB/HFB, ^c = HFB/CFB; ^# = pair t-test.

presents the results of meridian energy changes induced by footbaths in the three groups. The groups showed significant differences in the energy of the immune system (week 3, p = 0.022), skeletal muscle system (week 5, p = 0.070), liver function (week 4, p = 0.03), respiratory system (week 3, p = 0.013), and digestive system (week 4, p = 0.005). Specifically, the effects on the CFB group and WFB group on long-term meridian energy were larger than the HFb group.

Long-term energy changes were assessed by comparing the energy levels before (w0) and after (w7) intervention. The paired t-test analysis revealed that the CFB group had significant improvements in the long-term energy of the autonomic nervous system, skeletal muscle system, and respiratory system. Similarly, the WFB group showed significant improvements in the long-term energy of the total energy, endocrine system, and systemic report. However, the HFB group did not exhibit any significant changes in the energy levels of any physiological system. The WFB group showed a significant improvement in decreasing the energy levels of the cardiovascular system at the fourth (−10.89 ± 9.727), fifth (−17.22 ± 23.037), and sixth (−12.11 ± 15.964) weeks compared to those before intervention (w0). This finding was consistent with the experimental results presented in Table 2. Additionally, the WFB group showed a reduction in diastolic blood pressure, which supports and corroborates our results. Significant differences in immune, skeletal muscle, liver function, respiratory, and digestive system energy levels were also found. The CFB group improved the long-term energy of the autonomic nervous, skeletal muscle, and respiratory systems. The WFB group improved the total energy, endocrine, and systemic report energy levels and decreased cardiovascular system energy levels and diastolic blood pressure. However, the HFB group showed no effect of footbath on the energy levels of any physiological system.

4. Discussion

Footbath therapy has been an ancient health practice for centuries. With the prevalence of stress in today’s fast-paced work environment, finding effective health promotion methods to help employees learn and integrate stress management is crucial to achieving health self-management goals. To address this knowledge gap, we investigated the physiological effects of three footbath interventions: HFB, WFB, and CFB. The results showed that the CFB group had the best effects on reducing DBP, calf volume, and meridian energy. The ANOVA analysis of physiological parameters and meridian energy showed that the CFB group had the most significant adjusting effects, followed by the WFB and HFB groups.

Among the factors, CFB had the most significant impact, while the effect of HFB was the smallest. However, HFB provided better body-warming effects and health benefits for older adults and those who felt cold with poor circulation [4,12]. Although CFB is generally believed to have a stress-inducing effect on the cardiovascular system [13,14], the study results indicated that the impact on blood pressure was not enough for such an effect.

For the WFB, HFB, and CFB groups, total meridian energy changed significantly from the baseline at the end of the six-week intervention. However, no significant differences were observed after the fifth week. Based on the participants’ lifestyle records, There were academic exams in the fifth week, which might cause stress and poor sleep, and interfered with their normal physiological life cycle. The impact of this interference was less pronounced on calf volume. The results of SBP and DBP also showed a significant rebound in the WFB group in the fifth week, but a continuous decreasing trend in the sixth week after the interference was relieved. Similar observations were made for the HFB group in the fourth and fifth weeks. Nevertheless, the results for the CFB group indicated that changes in their lifestyle patterns had a smaller impact on the improvement trend in their data. The results of this study also showed that the CFB group showed better effects in adjusting DBP, reducing calf volume, and improving ankle circumference, flexibility, and meridian energy. Overall, body composition and meridian energy demonstrated that their adjusting effects were large for the CFB group > WFB group > HFB group in order.

For the parameters, CFB had a more substantial impact, while the effect of HFB was the smallest. Nevertheless, HFB provided better body-warming effects and health benefits for older adults who felt cold with poor circulation [4,12]. Although CFB is generally believed to have a stress-inducing effect on the cardiovascular system, this study’s results indicated that the impact on blood pressure was not large enough. These findings suggested that footbath therapy was an effective health promotion method for managing occupational stress and improving health self-management goals. Therefore, footbath therapy, specifically CFB, is recommended as a home health maintenance method.

5. Conclusions

We investigated the effects of three different footbath interventions on young adults. The WFB group showed a significant decrease in SBP from the third week, while the CFB group had the most significant impact on DBP in long-term follow-up. The CFB group had a significant reduction in calf volume, while the WFB group showed significant improvement in the energy levels of total energy and the cardiovascular system. These findings suggested that footbath therapy was effective in managing occupational stress, with CFB being particularly beneficial for health and stress management.