Impact of ao-dake-humi, Japanese traditional bamboo foot stimulator, on lower urinary tract symptoms, constipation and hypersensitivity to cold: a single-arm prospective pilot study

A total of 24 participants were enrolled in this study, and their characteristics are shown in Table 2. The results of subjective evaluation are shown in Table 3. The baseline of total IPSS, QoL score, and OABSS among LUTS patients is 14.7 ± 8.2, 4.3 ± 1.3, and 5.4 ± 3.6, respectively. Total IPSS, OABSS, and QoL score were improved after ao-dake-humi use in the participants with LUTS. In analysis of IPSS subscores, storage and postvoiding symptom subscores were significantly improved after ao-dake-humi use. As the first step to show the efficacy of ao-dake-humi on constipation and HC, evaluation was performed in this study using only VAS-constipation and VAS-HC. In accordance with the results, of the 11 participants with constipation, subjective VAS-constipation score was improved in −31.8% after ao-dake-humi use with statistical significance. Of the 17 participants with HC, subjective score was significantly improved in −21.9% of VAS-HC after ao-dake-humi use. The results of objective evaluation are shown in Table 4. Total urine volume did not change before and 28 days after starting ao-dake-humi use. Total and daytime urinary frequencies were decreased after ao-dake-humi use. These results may have been due to an increase in voided volume. Only the maximal voided volume increased significantly after ao-dake-humi use; mean and minimal voided volumes were also not significantly increased.

Previous reports indicated that a decrease in environmental temperature induces numerous physiological responses, including increased urinary frequency in both humans and animals [10, 11]. Previously, we reported the relationship between HC and LUTS, and the efficacy of simultaneous approaches using Kampo-medicine [2]. In this study, 60% of the enrolled participants had both LUTS and HC, and the efficacy of ao-dake-humi on HC was revealed subjectively. Moreover, constipation was also improved after ao-dake-humi use. Five of 11 participants with constipation had received drug treatment before starting this research. These results indicated that ao-dake-humi is a candidate therapeutic option to manage LUTS, constipation and HC. However, HC and constipation were evaluated on the basis of self-description using VAS. A further RCT with larger number of participants is needed.

Ao-dake-humi is a Japanese traditional home health appliance based on the theory of reflexology, and can be used at home to promote general health in daily use. Ao-dake-humi consists of a half-pipe-shaped foot-step made of bamboo cut into pieces 30–40 cm in length, and is widely used in Japan. The mechanisms of ao-dake-humi promoting general health are not yet known. However, neuromodulation and acupuncture may have similar mechanisms of action on LUTS, constipation and HC. Therefore, the effect of ao-dake-humi is thought not to be due to exercise but to stimulation of afferent nerves in the foot to modulate visceral organs, such as the urinary bladder and colon. Indeed, some neuromodulation equipment has been reported for treatment of LUTS, constipation and faecal incontinence [12]. Electrical stimulation [13‐18], magnetic stimulation [19‐22] and interferential therapy [23, 24] are mainly used for modulation via the sacral nerve or tibial nerve. Although the precise mechanisms of neuromodulation are not yet known, activation of afferent nerves may lead to activation of efferent nerves in the pelvic organs, including the urinary bladder and colon [13, 14]. Physical stimulation, such as acupuncture, reflexology or foot massage, can be used as a source of neuromodulation via activation of sensory afferent pathways. In addition, the theory of reflexology, including acupuncture, can also be adapted for ao-dake-humi, and our hypothesis about ao-dake-humi is described on Fig. 1a also. In reflexology, areas of the foot are believed to correspond to the organs or structures of the body [25]. Acupuncture was reported to have be effective for LUTS and constipation [26‐30]. Moreover, in accordance with the foot chart of oriental foot massage, the urinary bladder and colon are located in the “hot spot” of ao-dake-humi stimulation (Fig. 1b). Of course, the exercise effect of ao-dake-humi cannot be completely excluded in this study. Therefore, an RCT should be done between step-work-exercise versus ao-dake-humi.

Ao-dake-humi has many advantages, such as its inexpensiveness, portability, and less risk of harm, compared to other interventions, including electrical neuromodulation. Ao-dake-humi costs about 5 dollars, and requires little maintenance. Moreover, as ao-dake-humi can be shared, it can be used in public spaces, such as hospitals and nursing homes. Ao-dake-humi is lightweight (almost 300 g), and is therefore easily portable, and ideal for daily use at home. Even in comparison with other similar treatments, including acupuncture and massage, ao-dake-humi has advantages. For example, the amount of stimulation can be controlled procedure-dependently in normal foot massage. In contrast, the amount of stimulation of ao-dake-humi is controlled according to bodyweight and of each patient. The average body mass index of the participants was 21.8 kg/m², and obese participants were not included in this study. Although adequate methods should be proposed for participants with obesity in future studies, ao-dake-humi can standardise the amount of stimulation for patients. Adverse events associated with neuromodulation, such as infection, bleeding, pain, etc., have been reported [31, 32]. In this study, only three participants complained of slight pain due to ao-dake-humi use, and 98.5% of participants achieved use of ao-dake-humi according to a review of their diaries. All of the participants wished to continue ao-dake-humi use after this study. Even the participants that complained of slight pain at commencement of this study eventually felt comfortable with ao-dake-humi stimulation. There were no severe adverse events, such as diarrhea or urinary retention, among the participants. Of course, on theoretical grounds, it is impossible for the participants to have any severe advised events associated with use of ao-dake-humi. Compared with other neuromodulators, this is the unquestionable advantage of ao-dake-humi in management of LUTS and constipation.

However, this study had some limitations. In this pilot study, 2 sets/day of 2 min of ao-dake-humi were done for 28 days. There have been no reports regarding adequate use of ao-dake-humi. Time, duration, and frequency should be evaluated in future studies. The most important limitation of this study is bias because of its single-arm nature. Subjective results, such as IPSS and OABSS, should be interpreted carefully. However, objective results from FVC indicated that ao-dake-humi has efficacy for LUTS. Of course, objective evaluation should be performed even for constipation and HC, and more objective evaluation for LUTS, including uroflowmetry, residual urine volume, and cystometry, should also be performed in future studies. Lack of objective evaluation of constipation and HC is also a limitation of this study. However, object evaluation for constipation without any intervention is difficult, and object measurement of HC has not been established yet. Further investigation is needed to evaluate the exact role of ao-dake-humi on constipation and HC. However, even with these limitations, ao-dake-humi showed statistically relevant subjective and objective results in this study, and there were no adverse events. Thus, ao-dake-humi is a candidate of therapeutic option for LUTS, constipation and HC.