top of page

A systematic review and meta analysis: Effects of passive hydrotherapy WATSU

Published March 13th 2020 in PLoS ONE journal, the following is a systematic review and meta analysis of the applications, indications, and effects of passive hydrotherapy Watsu (WaterShiatsu). We took part in this study, which found beneficial effects of Watsu on pain, physical function, and mental issues.

From the article's Introduction:

"WATSU (portmanteau word: English "water" and Japanese 指圧 "Shiatsu”) was first described by its originator Dull in the 1980s as a treatment consisting of Japanese Shiatsu bodywork applied in thermal water. To practice WATSU, a therapist stands in thermoneutral water (35°C = 95°F = 308.15 K), supporting the supine receiver with hands, forearms, or shoulders and softly moving her / him in slow and spacious circular motion sequences following elaborate movement patterns related to receiver’s and therapist’s level of experience. The hands of the therapist function as a grip to facilitate movement and at the same time to stimulate acupuncture points. Gentle traction is applied to the body of the receiver to mobilize joints and stretch myofascial structures, as well asmeridians, channels through which the life-energy (Chinese 氣 “qi”, flows in the concept of Traditional Chinese Medicine. During immersion, hydrostatic pressure influences fluid distribution, metabolism, and respiration. The impact of gravity is greatly reduced, thus decreasing joint loads and allowing maximal flexibility in the positioning of the treated individual. The thermoneutral temperature of 35°C is recommended because it allows passive immersion of about 60 minutes without causing temperature-induced stress."


Background WATSU (portmanteau word: water and shiatsu) is a form of passive hydrotherapy in chest-deep thermoneutral water (35°C = 95°F = 308.15 K). It combines elements of myofascial stretching, joint mobilization, massage, and shiatsu and is reported to be used to address physical and mental issues. The objective of this systematic review (PROSPERO Registration No. CRD42016029347) and the meta-analyses was to assess the applications, indications, and the effects of WATSU to form a basis for further studies.

Methods A search for “WATSU OR watershiatsu OR (water AND shiatsu)” was conducted without any restrictions in 32 databases. Peer reviewed original articles addressing WATSU as a stand-alone hydrotherapy were assessed for risk of bias. Quantitative data of effects on pain, physical function, and mental issues were processed in random model meta-analyses with subgroup analyses by study design. Effect sizes were expressed as Hedges's g (± 95% confidence intervals).

Results Of 1,906 unique citations, 27 articles regardless of study design were assessed for risk of bias. WATSU has been applied to individuals of all ages. Indications covered acute (e.g. pregnancy related low back pain) and chronic conditions (e.g. cerebral palsy) with beneficial effects of WATSU regarding e.g. relaxation or sleep quality. Meta-analyses suggest beneficial effect sizes of WATSU on pain (overall Hedges’s g = -0.71, 95% CI = -0.91 to -0.51), physical function (overall Hedges’s g = -0.76, 95% CI = -1.08 to -0.44), and mental issues (overall Hedges’s g = -0.68, 95% CI = -1.02 to -0.35).

Conclusion Various applications, indications and beneficial effects of WATSU were identified. The grade of this evidence is estimated to be low to moderate at the best. To strengthen the findings of this study, high-quality RCTs are needed.

For full research article please visit PLOS ONE website:


Schitter AM, Fleckenstein J, Frei P, Taeymans J, Kurpiers N, Radlinger L (2020) Applications, indications, and effects of passive hydrotherapy WATSU (WaterShiatsu)—A systematic review and meta-analysis. PLoS ONE 15(3): e0229705.


bottom of page