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Does Aquatic Exercise Relieve Pain in Adults With Neurologic or Musculoskeletal Disease? A Systematic Review and Meta-Analysis of Randomized Controlled Trials

      Abstract

      Hall J, Swinkels A, Briddon J, McCabe CS. Does aquatic exercise relieve pain in adults with neurologic or musculoskeletal disease? A systematic review and meta-analysis of randomized controlled trials.

      Objective

      To evaluate the literature on the effectiveness of aquatic exercise in relieving pain in adults with neurologic or musculoskeletal disease.

      Data Sources

      A systematic literature search of 14 databases was examined for research on aquatic exercise over the period January 1980 to June 2006.

      Study Selection

      Randomized controlled trials (RCTs) that included adults with neurologic or musculoskeletal disease, pain as an outcome measure, and exercise in water were included.

      Data Extraction

      Information on the participants, interventions, and outcomes was extracted from the included studies. Quality appraisal was assessed using the Scottish Intercollegiate Guidelines Network criteria for RCTs.

      Data Synthesis

      Nineteen studies met the inclusion criteria; 8 were of moderate to low risk of bias, and 5 of these had data suitable for meta-analyses. This showed that aquatic exercise has a small posttreatment effect in relieving pain compared with no treatment (P=.04; standardized mean difference [SMD], −.17; 95% confidence interval [CI], −.33 to −.01), but it is not possible to draw a firm conclusion because of the lack of consistency of evidence across studies. Comparable pain-relieving effects were found between aquatic and land-based exercise (P=.56; SMD=.11; 95% CI, −.27 to .50).

      Conclusions

      There is sound evidence that there are no differences in pain-relieving effects between aquatic and land exercise. Compared with no treatment, aquatic exercise has a small pain-relieving effect; however, the small number of good-quality studies and inconsistency of results means that insufficient evidence limits firm conclusions. Future studies should aim for focused research questions on specific aquatic exercise techniques, using robust methodologic designs and detailed reporting of temperature, depth, and care setting.

      Key Words

      EXERCISE IN WARM WATER, usually termed hydrotherapy or aquatic exercise, is a popular treatment for many patients with painful neurologic or musculoskeletal conditions. Pain-relieving effects have been attributed to a wide variety of mechanisms. For example, the warmth and buoyancy of water may block nociception by acting on thermal and mechanoreceptors, thus influencing spinal segmental mechanisms.
      • Bender T.
      • Karaglle Z.
      • Bálint G.P.
      • Gutenbrunner C.
      • Bálint P.V.
      • Sukenik S.
      Hydrotherapy, balneotherapy, and spa treatment in pain management.
      • Lange U.
      • Muller-Ladner U.
      • Schmidt K.L.
      Balneotherapy in rheumatic disease—an overview of novel and known aspects.
      Also, the warmth of the water may enhance blood flow, which is thought to help in dissipating algogenic chemicals, and it may facilitate muscle relaxation. Other mechanisms are based around the effects of hydrostatic pressure, which by virtue of its effect on the cardiovascular system may relieve pain by reducing peripheral edema
      • Yamazaki F.
      • Endo Y.
      • Torii R.
      • Sagawa S.
      • Shiraki K.
      Continuous monitoring of change in hemodilution during water immersion in humans: effect of water temperature.
      and, centrally, by dampening sympathetic nervous activity.
      • Gabrielsen A.
      • Videbaek R.
      • Johansen L.B.
      • et al.
      Forearm vascular and neuroendocrine responses to graded water immersion in humans.
      • Mano T.
      Sympathetic nerve mechanisms of human adaptation to environment—findings obtained by microneurographic studies.
      Finally, the ease of movement many patients report may activate supraspinal pathways, resulting in a reduction in pain intensity.
      • Mior S.
      Exercise in the treatment of chronic pain.
      Given the diversity of analgesic pathways it is reasonable to speculate that all patients, irrespective of pain etiology, might benefit from aquatic exercise. Indeed, aquatic exercise is widely recognized as an important modality in the rehabilitation of patients with rheumatologic, orthopedic, and neurologic disorders.
      • Whitelock H.
      Hydrotherapy in the 1990s.
      In the United Kingdom, aquatic exercise for therapeutic purposes is recognized as a physical therapy−led treatment that uses the unique properties of water, “ideally in a purpose built, and suitably heated pool.”
      Hydrotherapy Association of Chartered Physiotherapists
      Guidance on good practice in hydrotherapy.
      (p5) This definition differs from the European approach in which balneotherapy, the medical application of natural thermal mineral waters, is usually associated with passive bathing, although sometimes exercise may be included.
      • Bender T.
      • Karaglle Z.
      • Bálint G.P.
      • Gutenbrunner C.
      • Bálint P.V.
      • Sukenik S.
      Hydrotherapy, balneotherapy, and spa treatment in pain management.
      • Lange U.
      • Muller-Ladner U.
      • Schmidt K.L.
      Balneotherapy in rheumatic disease—an overview of novel and known aspects.
      Despite the obvious differences between the 2, systematic reviews of balneotherapy have informed aquatic therapy practice.
      • Brosseau L.
      • Robinson V.
      • Léonard G.
      • et al.
      Efficacy of balneotherapy for rheumatoid arthritis: a meta-analysis.
      • Brosseau L.
      • MacLeay L.
      • Robinson V.
      • et al.
      Efficacy of balneotherapy for osteoarthritis of the knee: a systematic review.
      • Verhagen A.P.
      • Bierma-Zeinstra S.M.
      • Cardoso J.R.
      • de Bie R.A.
      • Boers M.
      • de Vet H.C.
      Balneotherapy for rheumatoid arthritis.
      • Karagülle M.Z.
      • Karagülle M.
      Balneotherapy and spa therapy of rheumatic diseases in Turkey: a systematic review.
      • Pittler M.H.
      • Karagülle M.Z.
      • Karagülle M.
      • Ernst E.
      Spa therapy and balneotherapy for treating low back pain: meta-analysis of randomized trials.
      Only 1 systematic review, conducted by a single reviewer, has been performed on aquatic exercise.
      • Geytenbeek J.
      Evidence for effective hydrotherapy.
      It considered all study designs, including those with co-interventions, and provides a detailed qualitative account of the effects of hydrotherapy on all outcomes mentioned. It did not specifically explore the effect of aquatic exercise on pain; nor did it evaluate the raw data on pain.
      In this study, we report a systematic review and meta-analysis of published randomized controlled trials (RCTs) that addresses the question: Does aquatic exercise relieve pain in adults with neurologic or musculoskeletal disease? This question has 2 elements: (1) Is aquatic exercise an effective treatment for pain (ie, better than no treatment)? and (2) How does pain relief in aquatic exercise compare with other interventions?

      Methods

      Search Strategy

      A search strategy was developed by iterative exploration of 18 databases using a variety of search terms that emphasized sensitivity (high recall) over specificity (precision).
      • Swinkels A.
      • Briddon J.
      • Hall J.
      Two physiotherapists, one librarian and a systematic literature review: collaboration in action.
      In the final search strategy, studies were sought from 14 databases, including Medline, AMED, EMBASE, SportDiscus, PEDro, CINAHL, ASSIA, and the Cochrane Library. Over the period January 1980 to June 2006, we used a range of search terms based around the concepts of aquatic exercise (hydrother$, balneo$, aquarobic$, aquatic rehab$, aqua$ and exercise, water and gymnast$, water aerobic$) and pain using the International Association for the Study of Pain terminology.
      Reference and bibliographic lists of retrieved articles and relevant reviews were also examined. The search was limited to English-language works and those that studied adults (people aged ≥18y).

      Study Selection

      A 3-stage process was used to select studies for inclusion in the review. In the first stage, the title of each identified article was checked against predetermined criteria by 2 reviewers using a standard form and coding sheet. Abstracts and full articles were similarly reviewed in the next 2 stages. In general, a policy of inclusion was adopted—that is, in the absence of any information to the contrary, each article was forwarded to the next stage of the screening process. Criteria for inclusion were titles, abstracts, and/or articles that suggested some aspect of aquatic exercise as defined in adults with neurologic or musculoskeletal pathology and with pain as an outcome measure. In addition, included studies were limited to full reports of RCTs that examined the effectiveness of aquatic exercise compared with no treatment or other interventions, such as land-based exercise or immersion, in adult patients (≥18y) with any neurologic or musculoskeletal pathology and in which at least 1 outcome measure of “subjective pain experience captured by ratings of pain intensity, sensation, and unpleasantness” was reported.
      • Morley S.
      • Eccleston C.
      • Williams A.
      Systematic review and meta-analysis of randomized controlled trials of cognitive behaviour therapy and behaviour therapy for chronic pain in adults, excluding headache.
      Studies that considered the prevention of pain in healthy conditions (eg, pregnancy) or which incorporated additional interventions (eg, education) were excluded from the review.

      Validity Assessment

      Selected studies were subject to unmasked quality assessment
      • Jadad A.R.
      • Moore R.A.
      • Carroll D.
      • et al.
      Assessing the quality of reports of randomized clinical trials: is blinding necessary?.
      by 2 reviewers using the criteria for RCTs recommended by the Scottish Intercollegiate Guidelines Network (SIGN 50).
      Scottish Intercollegiate Guideline Network
      SIGN 50: a guideline developers' handbook.
      An overall assessment of the 9 questions provides a bias rating of low (++), moderate (+), or high (−). A low bias rating indicates a high-quality study in which all or most of the 9 criteria have been fulfilled and where they have not been fulfilled the conclusions of the study are thought unlikely to alter. One study was authored by a reviewer and was therefore assessed by another independent reviewer.

      Data Extraction and Analysis

      Data extraction was completed using a pilot-tested form to capture information on a range of details including study design, participants, interventions, and outcome measures. All of the primary pain outcomes were continuous and, where it was possible to pool data, meta-analysis was conducted on the results of studies of high to moderate quality
      • Deeks J.J.
      • Higgins J.P.T.
      • Altman D.G.
      Analysing and presenting results.
      using the Cochrane Collaboration's review manager software.
      RevMan, version 4.2.9; Cochrane Collaboration, Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe St, Mail Rm W5010, Baltimore, MD 21205.
      Tables of comparisons were set up comparing aquatic exercise with no treatment and with interventions of dry-land exercise and immersion. A random effects model, weighted by sample size, was used to analyze end scores based on posttreatment differences between aquatic exercise and these comparison groups.
      • Moher D.
      • Jadad A.R.
      • Klassen T.P.
      Guides for reading and interpreting systematic reviews: III How did the authors synthesize the data and make their conclusions?.
      Changes in these scores (effect sizes = [mean1 − mean2]/pooled standard deviation [SD]) and 95% confidence intervals (CIs) were measured in units of SD (standardized mean difference [SMD]) and illustrated graphically using forest plots. Variation in the measured effect was explored using a statistical test for heterogeneity; nonsignificance indicates that the results of the different studies are similar.
      • Lau J.
      • Ioannidis J.P.
      • Schmid C.H.
      Quantitative synthesis in systematic reviews.
      When possible, sensitivity was examined by assessing the effect of removing studies with small sample sizes (low weighting) from the analysis. In addition, between-group differences for all studies, irrespective of quality, were examined for consistency and, in the absence of suitable data, study texts and significance tests were scrutinized. Conclusions were based on both quantitative and qualitative assessment of studies with low to moderate risk of bias.

      Results

      Trial Flow

      Seven hundred ninety-three publications were identified and screened against the inclusion and exclusion criteria. Of these publications, 729 were rejected at the title and abstract stage (fig 1). Sixty-nine studies proceeded to the paper screening stage, and 19 of these were accepted for review.
      • Minor M.A.
      • Hewett J.E.
      • Webel R.R.
      • Anderson S.K.
      • Kay D.R.
      Efficacy of physical conditioning exercise in patients with rheumatoid arthritis and osteoarthritis.
      • Sylvester K.L.
      Investigation of the effect of hydrotherapy in the treatment of osteoarthritic hips.
      • Green J.
      • McKenna F.
      • Redfern E.J.
      • Chamberlain M.A.
      Home exercises are as effective as outpatient hydrotherapy for osteoarthritis of the hip.
      • Ahern M.
      • Nicholls E.
      • Simionato E.
      • Clark M.
      • Bond M.
      Clinical and psychological effects of hydrotherapy in rheumatic diseases.
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      • Rintala P.
      • Kettunen H.
      • McCubbin J.A.
      Effects of a water exercise program for individuals with rheumatoid arthritis.
      • Sjogren T.
      • Long N.
      • Storay I.
      • Smith J.
      Group hydrotherapy versus group land-based treatment for chronic low back pain.
      • McIlveen B.
      • Robertson V.J.
      A randomised controlled study of the outcome of hydrotherapy for subjects with low back or back and leg pain.
      • Jentoft E.S.
      • Kvalvik A.G.
      • Mengshoel A.M.
      Effects of pool-based aerobic exercise on women with fibromyalgia/chronic widespread muscle pain.
      • Patrick D.L.
      • Ramsey S.D.
      • Spencer A.C.
      • Kinne S.
      • Belza B.
      • Topolski T.
      Economic evaluation of aquatic exercise for persons with osteoarthritis.
      • Sutherland G.
      • Andersen M.B.
      • Stoové M.A.
      Can aerobic exercise training affect health-related quality of life for people with multiple sclerosis?.
      • Wyatt F.B.
      • Milam S.
      • Manske R.C.
      • Deere R.
      The effects of aquatic and traditional exercise programs on persons with knee osteoarthritis.
      • Foley A.
      • Halbert J.
      • Hewitt T.
      • Crotty M.
      Does hydrotherapy improve strength and physical function in patients with osteoarthritis—a randomised controlled trial comparing a gym based and a hydrotherapy based strengthening programme.
      • Altan L.
      • Bingöl U.
      • Aykaç M.
      • Koç Z.
      • Yurtkuran M.
      Investigation of the effects of pool-based exercise on fibromyalgia syndrome.
      • Yozbatiran N.
      • Yildirim Y.
      • Parlak B.
      Effects of fitness and aquafitness exercises on physical fitness in patients with chronic low back pain.
      • Bilberg A.
      • Ahlmén M.
      • Mannerkorpi K.
      Moderately intensive exercise in a temperate pool for patients with rheumatoid arthritis: a randomized controlled study.
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      • Assis M.R.
      • Silva L.E.
      • Alves A.M.
      • et al.
      A randomized controlled trial of deep water running: clinical effectiveness of aquatic exercise to treat fibromyalgia.
      • Gusi N.
      • Tomas-Carus P.
      • Häkkinen A.
      • Häkkinen K.
      • Ortega-Alonso A.
      Exercise in waist-high warm water decreases pain and improves health-related quality of life and strength in the lower extremities in women with fibromyalgia.
      Of the 19, 5 studies were of sufficient quality and had adequate raw data to be entered into meta-analyses under one of 2 comparisons: aquatic exercise versus no-treatment controls and aquatic versus dry land exercise. The study selection and validity assessment process was undertaken by 2 independent reviewers. Where anomalies existed, discussion between the reviewers enabled consensus to be achieved.

      Study Characteristics

      Nine studies compared aquatic exercise with no-treatment or waiting-list control groups,
      • Ahern M.
      • Nicholls E.
      • Simionato E.
      • Clark M.
      • Bond M.
      Clinical and psychological effects of hydrotherapy in rheumatic diseases.
      • Rintala P.
      • Kettunen H.
      • McCubbin J.A.
      Effects of a water exercise program for individuals with rheumatoid arthritis.
      • McIlveen B.
      • Robertson V.J.
      A randomised controlled study of the outcome of hydrotherapy for subjects with low back or back and leg pain.
      • Patrick D.L.
      • Ramsey S.D.
      • Spencer A.C.
      • Kinne S.
      • Belza B.
      • Topolski T.
      Economic evaluation of aquatic exercise for persons with osteoarthritis.
      • Sutherland G.
      • Andersen M.B.
      • Stoové M.A.
      Can aerobic exercise training affect health-related quality of life for people with multiple sclerosis?.
      • Foley A.
      • Halbert J.
      • Hewitt T.
      • Crotty M.
      Does hydrotherapy improve strength and physical function in patients with osteoarthritis—a randomised controlled trial comparing a gym based and a hydrotherapy based strengthening programme.
      • Bilberg A.
      • Ahlmén M.
      • Mannerkorpi K.
      Moderately intensive exercise in a temperate pool for patients with rheumatoid arthritis: a randomized controlled study.
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      • Gusi N.
      • Tomas-Carus P.
      • Häkkinen A.
      • Häkkinen K.
      • Ortega-Alonso A.
      Exercise in waist-high warm water decreases pain and improves health-related quality of life and strength in the lower extremities in women with fibromyalgia.
      10 compared it with land exercise,
      • Minor M.A.
      • Hewett J.E.
      • Webel R.R.
      • Anderson S.K.
      • Kay D.R.
      Efficacy of physical conditioning exercise in patients with rheumatoid arthritis and osteoarthritis.
      • Sylvester K.L.
      Investigation of the effect of hydrotherapy in the treatment of osteoarthritic hips.
      • Green J.
      • McKenna F.
      • Redfern E.J.
      • Chamberlain M.A.
      Home exercises are as effective as outpatient hydrotherapy for osteoarthritis of the hip.
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      • Sjogren T.
      • Long N.
      • Storay I.
      • Smith J.
      Group hydrotherapy versus group land-based treatment for chronic low back pain.
      • Jentoft E.S.
      • Kvalvik A.G.
      • Mengshoel A.M.
      Effects of pool-based aerobic exercise on women with fibromyalgia/chronic widespread muscle pain.
      • Wyatt F.B.
      • Milam S.
      • Manske R.C.
      • Deere R.
      The effects of aquatic and traditional exercise programs on persons with knee osteoarthritis.
      • Foley A.
      • Halbert J.
      • Hewitt T.
      • Crotty M.
      Does hydrotherapy improve strength and physical function in patients with osteoarthritis—a randomised controlled trial comparing a gym based and a hydrotherapy based strengthening programme.
      • Yozbatiran N.
      • Yildirim Y.
      • Parlak B.
      Effects of fitness and aquafitness exercises on physical fitness in patients with chronic low back pain.
      • Assis M.R.
      • Silva L.E.
      • Alves A.M.
      • et al.
      A randomized controlled trial of deep water running: clinical effectiveness of aquatic exercise to treat fibromyalgia.
      and 2 with immersion
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      • Altan L.
      • Bingöl U.
      • Aykaç M.
      • Koç Z.
      • Yurtkuran M.
      Investigation of the effects of pool-based exercise on fibromyalgia syndrome.
      (table 1). Two studies incorporated more than 2 treatment arms.
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      • Foley A.
      • Halbert J.
      • Hewitt T.
      • Crotty M.
      Does hydrotherapy improve strength and physical function in patients with osteoarthritis—a randomised controlled trial comparing a gym based and a hydrotherapy based strengthening programme.
      Table 1Summary Description of the 19 Studies Included in the Review
      Study (Country)Participants
      • A. Condition
      • B. Duration of symptoms (mean ± SD; range [y])
      • C. Age (mean ± SD; range [y])
      • D. Men:women
      Comparison GroupsIntervention
      • A. Aims and content
      • B. Duration of program
      • C. Setting and pool temperature
      “Primary” Pain Outcomes and TimingResults of “Primary Pain Outcomes” According to StudyCalculated Effect Size (95% CI)
      Minor et al
      • Minor M.A.
      • Hewett J.E.
      • Webel R.R.
      • Anderson S.K.
      • Kay D.R.
      Efficacy of physical conditioning exercise in patients with rheumatoid arthritis and osteoarthritis.
      (USA)
      • A. RA and OA
      • B. RA: 10.8±7.9; OA: 14.6±10.7
      • C. 60.63 (21−83)
      • D. 22:98
      • 1
        Aquatic exercise (n=47)
      • 2
        Land-based exercise: aerobic walking (n=36)
      • 3
        Land-based exercise: range of motion (n=32)
      • A. The aim of groups 1 and 2 was aerobic conditioning. Participants exercised at 60%−80% of maximal heart rate.
      • B. 60min 3 times a week for 12wk
      • C. NR
      Pain subscale of AIMS at 0, 12, 24, and 52wkSignificant improvement of all groups at different time points (P<.05). No significant differences between interventions.0.28 (–0.21 to 0.76)
      Sylvester
      • Sylvester K.L.
      Investigation of the effect of hydrotherapy in the treatment of osteoarthritic hips.
      (UK)
      • A. Hip OA
      • B. 4 (2−8)
      • C. 66 (9−81)
      • D. 5:9
      • 1
        Aquatic exercise (n=7)
      • 2
        Land-based exercises and short-wave diathermy (n=7)
      • A. Both groups performed hip exercises and walking
      • B. 30min twice a week for 6wk
      • C. NR
      VAS at 0 and 7wkSignificant improvement in both groups (P<.02). No significant differences between interventions.DNA
      Green et al
      • Green J.
      • McKenna F.
      • Redfern E.J.
      • Chamberlain M.A.
      Home exercises are as effective as outpatient hydrotherapy for osteoarthritis of the hip.
      (UK)
      • A. Hip OA
      • B. NR
      • C. 68±NR
      • D. 12:35
      • 1
        Aquatic exercise (n=24)
      • 2
        Land-based exercise (n=23)
      • A. Both groups: to mobilize and strengthen hip
      • B. Twice weekly for 6wk
      • C. Hospital pool (temp NR ([deep pool])
      VAS at 0, 3, 6, 9, 12, and 18wkSignificant improvement in both groups. No significant differences between interventions.DNA
      Ahern et al
      • Ahern M.
      • Nicholls E.
      • Simionato E.
      • Clark M.
      • Bond M.
      Clinical and psychological effects of hydrotherapy in rheumatic diseases.
      (Australia)
      • A. RA/OA
      • B. 9.4±12
      • C. 67.7±7.1
      • D. 17:13
      • 1
        Aquatic exercise (n=22)
      • 2
        No-treatment control (n=8)
      • A. Group 1: to maximize mobility and function, reduce pain in the target joints
      • B. 30min twice a week for 6wk
      • C. Hospital pool, 34°C
      VAS for pain at 1, 2, 4, 6wkAt study end patients who continued with aquatic exercise after phase 1 maintained improvement in pain relief, whereas those who were assigned to the no-treatment control group did not.DNA
      Hall et al
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      (UK)
      • A. RA
      • B. 11.5±8.7
      • C. 58.2±11.1
      • D. 43:96
      • 1
        Aquatic exercise (n=35)
      • 2
        Land-based exercise (n=34)
      • 3
        Immersion (n=35)
      • 4
        Land relaxation (n=35)
      • A. Groups 1 and 2: to increase ROM and muscle strength of upper and lower limbs
      • B. 30min twice a week for 4wk
      • C. Hospital pool (temp NR)
      McGill Pain Questionnaire at 0, 4, and 12wkNo significant differences between interventions.0.10 (–0.37 to 0.57)
      Rintala et al
      • Rintala P.
      • Kettunen H.
      • McCubbin J.A.
      Effects of a water exercise program for individuals with rheumatoid arthritis.
      (Finland)
      • A. RA
      • B. 1.4 (1−27)
      • C. 48±10
      • D. 5:29
      • 1
        Aquatic exercise (n=18)
      • 2
        No-treatment control (n=16)
      • A. Group 1: to improve fitness, including aerobic power, muscle strength and endurance, and joint mobility. Ratings of perceived exertion used as measure of exercise intensity.
      • B. 45−60min twice a week for 12wk
      • C. NR
      VAS at 0 and 12wkAquatic exercise relieved pain significantly compared with control (P=.044).–0.87 (–1.58 to –0.17)
      Sjogren et al
      • Sjogren T.
      • Long N.
      • Storay I.
      • Smith J.
      Group hydrotherapy versus group land-based treatment for chronic low back pain.
      (Australia)
      • A. CLBP
      • B. 8.72±7.13
      • C. 57.7±12.6
      • D. 17:43
      • 1
        Aquatic exercise (n=30)
      • 2
        Land-based exercise (n=30)
      • A. Aim of both groups was to increase truncal movement, improve general strength and endurance
      • B. 50min twice a week for 6wk
      • C. NR
      VAS at baseline and 6wkSignificant improvement of both groups (P=.001). No significant differences between interventions.–0.02 (–0.54 to 0.51)
      McIlveen and Robertson
      • McIlveen B.
      • Robertson V.J.
      A randomised controlled study of the outcome of hydrotherapy for subjects with low back or back and leg pain.
      (Australia)
      • A. CLBP
      • B. 10.13±NR
      • C. 57.8±15.1
      • D. 38:57
      • 1
        Aquatic exercise (n=56)
      • 2
        Waiting list control/no treatment (n=53)
      • A. Group 1: general exercises for the spine
      • B. 60min twice a week for 4wk
      • C. NR
      McGill Pain Questionnaire at 0 and 4wkNo significant differences between interventions.DNA
      Jentoft et al
      • Jentoft E.S.
      • Kvalvik A.G.
      • Mengshoel A.M.
      Effects of pool-based aerobic exercise on women with fibromyalgia/chronic widespread muscle pain.
      (Norway)
      • A. Fibromyalgia
      • B. 11.1±14.1
      • C. 42.9±8.6
      • D. 0:44
      • 1
        Aquatic exercise (n=22)
      • 2
        Land-based exercise (n=22)
      • A. Both groups: to improve cardiovascular capacity using the Norwegian aerobic fitness model. Participants exercised at 60%−80% of predicted maximal heart rate for 40%−50% of each session.
      • B. 60min twice a week for 20wk
      • C. Hospital pool, 34°C
      VAS at 0, 24, and 46wkSignificant improvement in aquatic exercise group (P=.006). No significant differences between interventions.0.14 (–0.45 to 0.74)
      Patrick et al
      • Patrick D.L.
      • Ramsey S.D.
      • Spencer A.C.
      • Kinne S.
      • Belza B.
      • Topolski T.
      Economic evaluation of aquatic exercise for persons with osteoarthritis.
      (USA)
      • A. OA
      • B. NR
      • C. 65.7±NR
      • D. 34:214
      • 1
        Aquatic exercise (n=124)
      • 2
        No treatment/delayed treatment (n=125)
      • A. Group 1: consisted of Arthritis Foundation−certified aquatic class
      • B. 45−60min at least twice weekly for 20wk
      • C. Community pools, 29.5°−33.3°C
      Pain subscale of HAQ at 0 and 20wkNo significant differences between interventions.–0.12 (–0.37 to 0.13)
      Sutherland et al
      • Sutherland G.
      • Andersen M.B.
      • Stoové M.A.
      Can aerobic exercise training affect health-related quality of life for people with multiple sclerosis?.
      (Australia)
      • A. Multiple sclerosis
      • B. 10.8±NR
      • C. 46.3±4.9
      • D. 10:12
      • 1
        Aquatic exercise (n=11)
      • 2
        No-treatment control (n=11)
      • A. Group 1: water aerobics, water jogging, deep water running
      • B. 45min 3 times a week for 10wk
      • C. NR
      Pain subscale of MSQOL-54 at 0 and 8wkAquatic exercise relieved pain significantly compared with control (P=.01).0.21 (–0.60 to 1.04)
      Wyatt et al
      • Wyatt F.B.
      • Milam S.
      • Manske R.C.
      • Deere R.
      The effects of aquatic and traditional exercise programs on persons with knee osteoarthritis.
      (Sweden)
      • A. Knee OA
      • B. NR
      • C. NR (45−70)
      • D. NR
      • 1
        Aquatic exercise
      • 2
        Land-based exercise (overall, n=46)
      • A. Both groups performed knee exercises
      • B. 3 times a week for 6wk
      • C. Therapeutic pool, 32.2°C (1.5m [5ft] deep)
      VAS at 0 and 6wkAquatic exercise relieved pain significantly compared with control (P≤.05).–0.86 (–1.49 to –0.22)
      Foley et al
      • Foley A.
      • Halbert J.
      • Hewitt T.
      • Crotty M.
      Does hydrotherapy improve strength and physical function in patients with osteoarthritis—a randomised controlled trial comparing a gym based and a hydrotherapy based strengthening programme.
      (Australia)
      • A. Hip/knee OA
      • B. NR
      • C. 70.9±8.8
      • D. 53:52
      • 1
        Aquatic exercise (n=35)
      • 2
        Land-based exercise (n=35)
      • 3
        No-treatment control (n=35)
      • A. Groups 1 and 2: to strengthen lower-limb musculature and improve physical function.
      • B. 30min 3 times a week for 6wk
      • C. Hospital pool, gym (temp NR)
      Pain subscale of WOMAC at 0 and 6wkSignificant improvement in aquatic exercise group (P=.045). No significant differences between interventions.DNA
      Altan et al
      • Altan L.
      • Bingöl U.
      • Aykaç M.
      • Koç Z.
      • Yurtkuran M.
      Investigation of the effects of pool-based exercise on fibromyalgia syndrome.
      (Turkey)
      • A. Fibromyalgia
      • B. NR
      • C. 43.14±6.4
      • D. 0:50
      • 1
        Aquatic exercise (n=25)
      • 2
        Immersion (n=25)
      • A. Group 1: walking, jumping, active ROM exercise for the neck and extremities, stretching, relaxation. Group 2: patients were instructed not to perform any exercises.
      • B. 70min 3 times a week for 12wk
      • C. Therapeutic pool, 37°C
      VAS at 0, 12, and 24wkSignificant improvement of both groups (P<.05). No significant differences between interventions.0.08 (–0.48 to 0.63)
      Yozbatiran et al
      • Yozbatiran N.
      • Yildirim Y.
      • Parlak B.
      Effects of fitness and aquafitness exercises on physical fitness in patients with chronic low back pain.
      (Turkey)
      • A. CLBP
      • B. NR
      • C. 39.07±6.35
      • D. 7:23
      • 1
        Aquatic exercise (n=15)
      • 2
        Land-based exercise (n=15)
      • A. Both followed the program advocated by Frost et al
        • Frost H.
        • Lamb S.E.
        • Klaber Moffett J.A.
        • Fairbank J.C.
        • Moser J.S.
        A fitness programme for patients with chronic low back pain: 2-year follow-up of a randomised controlled trial.
        including warm-up, stretching, circuit of 15 progressive exercises, cool down with light stretching and light aerobic exercise.
      • B. 3 times a week for 12wk
      • C. NR
      VAS for pain at 0 and 4wkSignificant improvement of both groups (P=.02). No significant differences between interventions.–0.36 (–1.08 to 0.36)
      Bilberg et al
      • Bilberg A.
      • Ahlmén M.
      • Mannerkorpi K.
      Moderately intensive exercise in a temperate pool for patients with rheumatoid arthritis: a randomized controlled study.
      (Sweden)
      • A. RA
      • B. 2.75±1.37
      • C. NR (21−65)
      • D. 5:42
      • 1
        Aquatic exercise (n=22)
      • 2
        No-treatment control/usual home exercises (n=25)
      • A. Group 1: exercises for aerobic capacity, dynamic and static muscle strength in upper and lower limbs, flexibility, coordination, and relaxation
      • B. 45min twice a week for 12wk
      • C. NR, temperate pool
      Pain subscale of SF-36 at 1 and 12wk (and for aquatic exercise group 24wk)Significant improvement of both groups (P<.05). No significant differences between interventions.0.00 (–0.60 to 0.59)
      Cochrane et al
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      (UK)
      • A. Lower-limb OA
      • B. NR
      • C. 69.7±6.5
      • D. 116:196
      • 1
        Aquatic exercise (n=153)
      • 2
        No-treatment control (n=159)
      • A. Group 1: standard 5-phase exercise protocol consisting of warm-up, joint ROM exercises, muscle strengthening, coordination and balance exercises, and general cardiovascular conditioning exercises
      • B. 60min twice a week for 1y
      • C. Public swimming pools, 28°−33°C.
      Pain subscale of WOMAC at 0, 12, and 18moAquatic exercise relieved pain significantly compared with control (P=.031). Improvements had been lost by follow-up.–0.24 (–0.47 to –0.02)
      Assis et al
      • Assis M.R.
      • Silva L.E.
      • Alves A.M.
      • et al.
      A randomized controlled trial of deep water running: clinical effectiveness of aquatic exercise to treat fibromyalgia.
      (Brazil)
      • A. Fibromyalgia
      • B. 6.04±4.86
      • C. 42.8±10.4
      • D. 0:60
      • 1
        Aquatic exercise (n=30)
      • 2
        Land-based exercise (n=30)
      • A. Both groups: aerobic conditioning using heart rate at anaerobic threshold as intensity marker.
      • B. 45min 3 times a week for 15wk
      • C. Sport and physical medical center and local park, 28°−31°C
      VAS for pain at 0, 8, and 15wkSignificant improvement of both groups (P<.001, pain reduced by 36%). No significant differences between interventions.DNA
      Gusi et al
      • Gusi N.
      • Tomas-Carus P.
      • Häkkinen A.
      • Häkkinen K.
      • Ortega-Alonso A.
      Exercise in waist-high warm water decreases pain and improves health-related quality of life and strength in the lower extremities in women with fibromyalgia.
      (Finland)
      • A. Fibromyalgia
      • B. 21.5±8.5
      • C. 51±9.5
      • D. 0:35
      • 1
        Aquatic exercise (n=18)
      • 2
        No-treatment control (n=17)
      • A. Group 1: exercise included warm-up, aerobic exercise at 65%−75% predicted maximal heart rate, overall mobility and lower-limb strength exercises and cool down
      • B. 60min 3 times a week for 12wk
      • C. NR, 33°C (waist-high pool)
      VAS for pain at 0, 12, and 24wkAquatic exercise relieved pain significantly compared with control (P<.05). Improvements had been lost by follow-up.DNA
      Abbreviations: AIMS, Arthritis Impact Measurement Scale; CLBP, chronic low-back pain; DNA, data not available for effect size calculation; HAQ, Health Assessment Questionnaire; MSQOL-54, Multiple Sclerosis Quality of Life−54; NR, not recorded; OA, osteoarthritis; RA, rheumatoid arthritis; ROM, range of motion; SF-36, 36-Item Short Form Health Survey; VAS, visual analog scale; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.

      Participants

      Within the 19 studies, 717 patients participated in hydrotherapy, with an average age of 56.0±11.3 years (range, 25–81y) and, based on available data, an overall men-to-women ratio of 1:3 (not all studies reported this). The number of subjects randomized to the aquatic exercise arm ranged from 7 to 153, with 1 study omitting to report how many patients were randomized to the different treatment arms.
      • Wyatt F.B.
      • Milam S.
      • Manske R.C.
      • Deere R.
      The effects of aquatic and traditional exercise programs on persons with knee osteoarthritis.
      Most patients presented with rheumatology conditions, and only Sutherland et al
      • Sutherland G.
      • Andersen M.B.
      • Stoové M.A.
      Can aerobic exercise training affect health-related quality of life for people with multiple sclerosis?.
      involved patients with neurologic problems. Of the rheumatology articles, 4 considered fibromyalgia,
      • Jentoft E.S.
      • Kvalvik A.G.
      • Mengshoel A.M.
      Effects of pool-based aerobic exercise on women with fibromyalgia/chronic widespread muscle pain.
      • Altan L.
      • Bingöl U.
      • Aykaç M.
      • Koç Z.
      • Yurtkuran M.
      Investigation of the effects of pool-based exercise on fibromyalgia syndrome.
      • Assis M.R.
      • Silva L.E.
      • Alves A.M.
      • et al.
      A randomized controlled trial of deep water running: clinical effectiveness of aquatic exercise to treat fibromyalgia.
      • Gusi N.
      • Tomas-Carus P.
      • Häkkinen A.
      • Häkkinen K.
      • Ortega-Alonso A.
      Exercise in waist-high warm water decreases pain and improves health-related quality of life and strength in the lower extremities in women with fibromyalgia.
      3 chronic low back pain,
      • Sjogren T.
      • Long N.
      • Storay I.
      • Smith J.
      Group hydrotherapy versus group land-based treatment for chronic low back pain.
      • McIlveen B.
      • Robertson V.J.
      A randomised controlled study of the outcome of hydrotherapy for subjects with low back or back and leg pain.
      • Yozbatiran N.
      • Yildirim Y.
      • Parlak B.
      Effects of fitness and aquafitness exercises on physical fitness in patients with chronic low back pain.
      and 11 osteoarthritis or rheumatoid arthritis.
      • Minor M.A.
      • Hewett J.E.
      • Webel R.R.
      • Anderson S.K.
      • Kay D.R.
      Efficacy of physical conditioning exercise in patients with rheumatoid arthritis and osteoarthritis.
      • Sylvester K.L.
      Investigation of the effect of hydrotherapy in the treatment of osteoarthritic hips.
      • Green J.
      • McKenna F.
      • Redfern E.J.
      • Chamberlain M.A.
      Home exercises are as effective as outpatient hydrotherapy for osteoarthritis of the hip.
      • Ahern M.
      • Nicholls E.
      • Simionato E.
      • Clark M.
      • Bond M.
      Clinical and psychological effects of hydrotherapy in rheumatic diseases.
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      • Rintala P.
      • Kettunen H.
      • McCubbin J.A.
      Effects of a water exercise program for individuals with rheumatoid arthritis.
      • Patrick D.L.
      • Ramsey S.D.
      • Spencer A.C.
      • Kinne S.
      • Belza B.
      • Topolski T.
      Economic evaluation of aquatic exercise for persons with osteoarthritis.
      • Foley A.
      • Halbert J.
      • Hewitt T.
      • Crotty M.
      Does hydrotherapy improve strength and physical function in patients with osteoarthritis—a randomised controlled trial comparing a gym based and a hydrotherapy based strengthening programme.
      • Bilberg A.
      • Ahlmén M.
      • Mannerkorpi K.
      Moderately intensive exercise in a temperate pool for patients with rheumatoid arthritis: a randomized controlled study.
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      The duration of symptoms varied from 2.75 to 24.00 years with an average of 9.98±5.50 years.
      Drop-out rates for aquatic exercise patients ranged from 0% to 27.4%. Of the 3 studies with drop-out rates exceeding 20% (SIGN criterion), the time from baseline to posttest varied from 6 to 52 weeks. Extraneous causes such as comorbidity, time issues, or travel difficulties were responsible rather than the deleterious side effects of treatment. Three authors reported that a few patients (n=5) experienced an exacerbation of symptoms, but from the information provided, the treatment group affiliation of these patients is difficult to determine.
      • Green J.
      • McKenna F.
      • Redfern E.J.
      • Chamberlain M.A.
      Home exercises are as effective as outpatient hydrotherapy for osteoarthritis of the hip.
      • Sjogren T.
      • Long N.
      • Storay I.
      • Smith J.
      Group hydrotherapy versus group land-based treatment for chronic low back pain.
      • Foley A.
      • Halbert J.
      • Hewitt T.
      • Crotty M.
      Does hydrotherapy improve strength and physical function in patients with osteoarthritis—a randomised controlled trial comparing a gym based and a hydrotherapy based strengthening programme.

      Intervention

      Thirteen articles reported the aims of the aquatic exercise intervention and details, however brief, of the specific activities were mentioned in all. By categorizing the activities, it was possible to identify 3 types of exercise program: a general exercise program that included elements of muscle strengthening, increasing range of movement, and functional activities (n=9)
      • Sylvester K.L.
      Investigation of the effect of hydrotherapy in the treatment of osteoarthritic hips.
      • Green J.
      • McKenna F.
      • Redfern E.J.
      • Chamberlain M.A.
      Home exercises are as effective as outpatient hydrotherapy for osteoarthritis of the hip.
      • Ahern M.
      • Nicholls E.
      • Simionato E.
      • Clark M.
      • Bond M.
      Clinical and psychological effects of hydrotherapy in rheumatic diseases.
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      • Sjogren T.
      • Long N.
      • Storay I.
      • Smith J.
      Group hydrotherapy versus group land-based treatment for chronic low back pain.
      • McIlveen B.
      • Robertson V.J.
      A randomised controlled study of the outcome of hydrotherapy for subjects with low back or back and leg pain.
      • Patrick D.L.
      • Ramsey S.D.
      • Spencer A.C.
      • Kinne S.
      • Belza B.
      • Topolski T.
      Economic evaluation of aquatic exercise for persons with osteoarthritis.
      • Wyatt F.B.
      • Milam S.
      • Manske R.C.
      • Deere R.
      The effects of aquatic and traditional exercise programs on persons with knee osteoarthritis.
      • Altan L.
      • Bingöl U.
      • Aykaç M.
      • Koç Z.
      • Yurtkuran M.
      Investigation of the effects of pool-based exercise on fibromyalgia syndrome.
      ; aerobic exercise (n=9)
      • Minor M.A.
      • Hewett J.E.
      • Webel R.R.
      • Anderson S.K.
      • Kay D.R.
      Efficacy of physical conditioning exercise in patients with rheumatoid arthritis and osteoarthritis.
      • Rintala P.
      • Kettunen H.
      • McCubbin J.A.
      Effects of a water exercise program for individuals with rheumatoid arthritis.
      • Jentoft E.S.
      • Kvalvik A.G.
      • Mengshoel A.M.
      Effects of pool-based aerobic exercise on women with fibromyalgia/chronic widespread muscle pain.
      • Sutherland G.
      • Andersen M.B.
      • Stoové M.A.
      Can aerobic exercise training affect health-related quality of life for people with multiple sclerosis?.
      • Yozbatiran N.
      • Yildirim Y.
      • Parlak B.
      Effects of fitness and aquafitness exercises on physical fitness in patients with chronic low back pain.
      • Bilberg A.
      • Ahlmén M.
      • Mannerkorpi K.
      Moderately intensive exercise in a temperate pool for patients with rheumatoid arthritis: a randomized controlled study.
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      • Assis M.R.
      • Silva L.E.
      • Alves A.M.
      • et al.
      A randomized controlled trial of deep water running: clinical effectiveness of aquatic exercise to treat fibromyalgia.
      • Gusi N.
      • Tomas-Carus P.
      • Häkkinen A.
      • Häkkinen K.
      • Ortega-Alonso A.
      Exercise in waist-high warm water decreases pain and improves health-related quality of life and strength in the lower extremities in women with fibromyalgia.
      ; and strengthening exercise (n=1).
      • Foley A.
      • Halbert J.
      • Hewitt T.
      • Crotty M.
      Does hydrotherapy improve strength and physical function in patients with osteoarthritis—a randomised controlled trial comparing a gym based and a hydrotherapy based strengthening programme.
      Of the 9 articles in which aerobic exercise was reported, 5 based the exercise intensity on heart rate.
      • Minor M.A.
      • Hewett J.E.
      • Webel R.R.
      • Anderson S.K.
      • Kay D.R.
      Efficacy of physical conditioning exercise in patients with rheumatoid arthritis and osteoarthritis.
      • Rintala P.
      • Kettunen H.
      • McCubbin J.A.
      Effects of a water exercise program for individuals with rheumatoid arthritis.
      • Jentoft E.S.
      • Kvalvik A.G.
      • Mengshoel A.M.
      Effects of pool-based aerobic exercise on women with fibromyalgia/chronic widespread muscle pain.
      • Assis M.R.
      • Silva L.E.
      • Alves A.M.
      • et al.
      A randomized controlled trial of deep water running: clinical effectiveness of aquatic exercise to treat fibromyalgia.
      • Gusi N.
      • Tomas-Carus P.
      • Häkkinen A.
      • Häkkinen K.
      • Ortega-Alonso A.
      Exercise in waist-high warm water decreases pain and improves health-related quality of life and strength in the lower extremities in women with fibromyalgia.
      The intervention setting in 12 studies indicated that hospital or clinic pools were used. Three used community or public swimming pools, and 4 omitted to report the treatment setting. The overall duration of aquatic exercise treatment ranged from 6 weeks or less
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      • McIlveen B.
      • Robertson V.J.
      A randomised controlled study of the outcome of hydrotherapy for subjects with low back or back and leg pain.
      to more than 12 weeks,
      • Rintala P.
      • Kettunen H.
      • McCubbin J.A.
      Effects of a water exercise program for individuals with rheumatoid arthritis.
      • Jentoft E.S.
      • Kvalvik A.G.
      • Mengshoel A.M.
      Effects of pool-based aerobic exercise on women with fibromyalgia/chronic widespread muscle pain.
      • Patrick D.L.
      • Ramsey S.D.
      • Spencer A.C.
      • Kinne S.
      • Belza B.
      • Topolski T.
      Economic evaluation of aquatic exercise for persons with osteoarthritis.
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      • Assis M.R.
      • Silva L.E.
      • Alves A.M.
      • et al.
      A randomized controlled trial of deep water running: clinical effectiveness of aquatic exercise to treat fibromyalgia.
      with an average of 33.25±19.20 sessions. Treatments took place on an outpatient basis 2 to 3 times a week for a minimum of 30 and a maximum of 75 minutes (mean, 50.7±12.2min); 3 studies did not report session duration.
      • Green J.
      • McKenna F.
      • Redfern E.J.
      • Chamberlain M.A.
      Home exercises are as effective as outpatient hydrotherapy for osteoarthritis of the hip.
      • Wyatt F.B.
      • Milam S.
      • Manske R.C.
      • Deere R.
      The effects of aquatic and traditional exercise programs on persons with knee osteoarthritis.
      • Yozbatiran N.
      • Yildirim Y.
      • Parlak B.
      Effects of fitness and aquafitness exercises on physical fitness in patients with chronic low back pain.
      Total treatment time ranged from 4 to 84 hours (mean, 25.5±20.54; median, 22.5). Where reported, treatment was performed in groups of 4 to 24 patients supervised by physiotherapists (n=8) or trained instructors (n=5) and using programs designed by a physiotherapist or fitness professional (n=5). In 11 studies, the average temperature of the water was 32.4°±2.7°C (range, 28°–36°C). Only 4 studies reported the depth of the water,
      • Minor M.A.
      • Hewett J.E.
      • Webel R.R.
      • Anderson S.K.
      • Kay D.R.
      Efficacy of physical conditioning exercise in patients with rheumatoid arthritis and osteoarthritis.
      • Green J.
      • McKenna F.
      • Redfern E.J.
      • Chamberlain M.A.
      Home exercises are as effective as outpatient hydrotherapy for osteoarthritis of the hip.
      • Wyatt F.B.
      • Milam S.
      • Manske R.C.
      • Deere R.
      The effects of aquatic and traditional exercise programs on persons with knee osteoarthritis.
      • Gusi N.
      • Tomas-Carus P.
      • Häkkinen A.
      • Häkkinen K.
      • Ortega-Alonso A.
      Exercise in waist-high warm water decreases pain and improves health-related quality of life and strength in the lower extremities in women with fibromyalgia.
      which was between waist and chest height.

      Outcome Measurement

      Pain outcomes were measured before and after intervention in each reviewed study; follow-up data were reported in 8 studies.
      • Minor M.A.
      • Hewett J.E.
      • Webel R.R.
      • Anderson S.K.
      • Kay D.R.
      Efficacy of physical conditioning exercise in patients with rheumatoid arthritis and osteoarthritis.
      • Green J.
      • McKenna F.
      • Redfern E.J.
      • Chamberlain M.A.
      Home exercises are as effective as outpatient hydrotherapy for osteoarthritis of the hip.
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      • Jentoft E.S.
      • Kvalvik A.G.
      • Mengshoel A.M.
      Effects of pool-based aerobic exercise on women with fibromyalgia/chronic widespread muscle pain.
      • Altan L.
      • Bingöl U.
      • Aykaç M.
      • Koç Z.
      • Yurtkuran M.
      Investigation of the effects of pool-based exercise on fibromyalgia syndrome.
      • Bilberg A.
      • Ahlmén M.
      • Mannerkorpi K.
      Moderately intensive exercise in a temperate pool for patients with rheumatoid arthritis: a randomized controlled study.
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      • Gusi N.
      • Tomas-Carus P.
      • Häkkinen A.
      • Häkkinen K.
      • Ortega-Alonso A.
      Exercise in waist-high warm water decreases pain and improves health-related quality of life and strength in the lower extremities in women with fibromyalgia.
      A variety of instruments were used to measure sensory pain, with the 10-cm visual analog scale (VAS) being the most common.
      • Sylvester K.L.
      Investigation of the effect of hydrotherapy in the treatment of osteoarthritic hips.
      • Green J.
      • McKenna F.
      • Redfern E.J.
      • Chamberlain M.A.
      Home exercises are as effective as outpatient hydrotherapy for osteoarthritis of the hip.
      • Ahern M.
      • Nicholls E.
      • Simionato E.
      • Clark M.
      • Bond M.
      Clinical and psychological effects of hydrotherapy in rheumatic diseases.
      • Rintala P.
      • Kettunen H.
      • McCubbin J.A.
      Effects of a water exercise program for individuals with rheumatoid arthritis.
      • Sjogren T.
      • Long N.
      • Storay I.
      • Smith J.
      Group hydrotherapy versus group land-based treatment for chronic low back pain.
      • Jentoft E.S.
      • Kvalvik A.G.
      • Mengshoel A.M.
      Effects of pool-based aerobic exercise on women with fibromyalgia/chronic widespread muscle pain.
      • Wyatt F.B.
      • Milam S.
      • Manske R.C.
      • Deere R.
      The effects of aquatic and traditional exercise programs on persons with knee osteoarthritis.
      • Altan L.
      • Bingöl U.
      • Aykaç M.
      • Koç Z.
      • Yurtkuran M.
      Investigation of the effects of pool-based exercise on fibromyalgia syndrome.
      • Yozbatiran N.
      • Yildirim Y.
      • Parlak B.
      Effects of fitness and aquafitness exercises on physical fitness in patients with chronic low back pain.
      • Assis M.R.
      • Silva L.E.
      • Alves A.M.
      • et al.
      A randomized controlled trial of deep water running: clinical effectiveness of aquatic exercise to treat fibromyalgia.
      • Gusi N.
      • Tomas-Carus P.
      • Häkkinen A.
      • Häkkinen K.
      • Ortega-Alonso A.
      Exercise in waist-high warm water decreases pain and improves health-related quality of life and strength in the lower extremities in women with fibromyalgia.
      Other instruments included the McGill Pain Questionnaire
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      • McIlveen B.
      • Robertson V.J.
      A randomised controlled study of the outcome of hydrotherapy for subjects with low back or back and leg pain.
      and pain subscales from a variety of self-report questionnaires (Arthritis Impact Measurement Scale,
      • Minor M.A.
      • Hewett J.E.
      • Webel R.R.
      • Anderson S.K.
      • Kay D.R.
      Efficacy of physical conditioning exercise in patients with rheumatoid arthritis and osteoarthritis.
      Health Assessment Questionnaire,
      • Patrick D.L.
      • Ramsey S.D.
      • Spencer A.C.
      • Kinne S.
      • Belza B.
      • Topolski T.
      Economic evaluation of aquatic exercise for persons with osteoarthritis.
      health-related quality of life,
      • Sutherland G.
      • Andersen M.B.
      • Stoové M.A.
      Can aerobic exercise training affect health-related quality of life for people with multiple sclerosis?.
      Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC],
      • Foley A.
      • Halbert J.
      • Hewitt T.
      • Crotty M.
      Does hydrotherapy improve strength and physical function in patients with osteoarthritis—a randomised controlled trial comparing a gym based and a hydrotherapy based strengthening programme.
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      36-Item Short-Form Health Survey
      • Bilberg A.
      • Ahlmén M.
      • Mannerkorpi K.
      Moderately intensive exercise in a temperate pool for patients with rheumatoid arthritis: a randomized controlled study.
      ). Only 3 studies included pain as a primary outcome measure,
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      • Assis M.R.
      • Silva L.E.
      • Alves A.M.
      • et al.
      A randomized controlled trial of deep water running: clinical effectiveness of aquatic exercise to treat fibromyalgia.
      • Gusi N.
      • Tomas-Carus P.
      • Häkkinen A.
      • Häkkinen K.
      • Ortega-Alonso A.
      Exercise in waist-high warm water decreases pain and improves health-related quality of life and strength in the lower extremities in women with fibromyalgia.
      and 2 of these had used this pain outcome in a power calculation for sample size.

      Methodologic Quality

      Five studies were judged to be at low risk of bias using the SIGN criteria and are therefore judged as high quality.
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      • Patrick D.L.
      • Ramsey S.D.
      • Spencer A.C.
      • Kinne S.
      • Belza B.
      • Topolski T.
      Economic evaluation of aquatic exercise for persons with osteoarthritis.
      • Foley A.
      • Halbert J.
      • Hewitt T.
      • Crotty M.
      Does hydrotherapy improve strength and physical function in patients with osteoarthritis—a randomised controlled trial comparing a gym based and a hydrotherapy based strengthening programme.
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      • Assis M.R.
      • Silva L.E.
      • Alves A.M.
      • et al.
      A randomized controlled trial of deep water running: clinical effectiveness of aquatic exercise to treat fibromyalgia.
      Three studies were of moderate
      • Ahern M.
      • Nicholls E.
      • Simionato E.
      • Clark M.
      • Bond M.
      Clinical and psychological effects of hydrotherapy in rheumatic diseases.
      • Jentoft E.S.
      • Kvalvik A.G.
      • Mengshoel A.M.
      Effects of pool-based aerobic exercise on women with fibromyalgia/chronic widespread muscle pain.
      • Bilberg A.
      • Ahlmén M.
      • Mannerkorpi K.
      Moderately intensive exercise in a temperate pool for patients with rheumatoid arthritis: a randomized controlled study.
      and 11 studies
      • Minor M.A.
      • Hewett J.E.
      • Webel R.R.
      • Anderson S.K.
      • Kay D.R.
      Efficacy of physical conditioning exercise in patients with rheumatoid arthritis and osteoarthritis.
      • Sylvester K.L.
      Investigation of the effect of hydrotherapy in the treatment of osteoarthritic hips.
      • Green J.
      • McKenna F.
      • Redfern E.J.
      • Chamberlain M.A.
      Home exercises are as effective as outpatient hydrotherapy for osteoarthritis of the hip.
      • Rintala P.
      • Kettunen H.
      • McCubbin J.A.
      Effects of a water exercise program for individuals with rheumatoid arthritis.
      • Sjogren T.
      • Long N.
      • Storay I.
      • Smith J.
      Group hydrotherapy versus group land-based treatment for chronic low back pain.
      • McIlveen B.
      • Robertson V.J.
      A randomised controlled study of the outcome of hydrotherapy for subjects with low back or back and leg pain.
      • Sutherland G.
      • Andersen M.B.
      • Stoové M.A.
      Can aerobic exercise training affect health-related quality of life for people with multiple sclerosis?.
      • Wyatt F.B.
      • Milam S.
      • Manske R.C.
      • Deere R.
      The effects of aquatic and traditional exercise programs on persons with knee osteoarthritis.
      • Altan L.
      • Bingöl U.
      • Aykaç M.
      • Koç Z.
      • Yurtkuran M.
      Investigation of the effects of pool-based exercise on fibromyalgia syndrome.
      • Yozbatiran N.
      • Yildirim Y.
      • Parlak B.
      Effects of fitness and aquafitness exercises on physical fitness in patients with chronic low back pain.
      • Gusi N.
      • Tomas-Carus P.
      • Häkkinen A.
      • Häkkinen K.
      • Ortega-Alonso A.
      Exercise in waist-high warm water decreases pain and improves health-related quality of life and strength in the lower extremities in women with fibromyalgia.
      of low quality (table 2). Although all studies were described as randomized, most (91%) of those that had a high level of bias failed to meet this SIGN criterion. Other criteria that were frequently inadequate included randomization concealment and intention-to-treat analysis (both n=14 [73.6%]). Although a priori power calculations are not included within the SIGN checklist we noted that only 6 studies
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      • McIlveen B.
      • Robertson V.J.
      A randomised controlled study of the outcome of hydrotherapy for subjects with low back or back and leg pain.
      • Patrick D.L.
      • Ramsey S.D.
      • Spencer A.C.
      • Kinne S.
      • Belza B.
      • Topolski T.
      Economic evaluation of aquatic exercise for persons with osteoarthritis.
      • Foley A.
      • Halbert J.
      • Hewitt T.
      • Crotty M.
      Does hydrotherapy improve strength and physical function in patients with osteoarthritis—a randomised controlled trial comparing a gym based and a hydrotherapy based strengthening programme.
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      • Assis M.R.
      • Silva L.E.
      • Alves A.M.
      • et al.
      A randomized controlled trial of deep water running: clinical effectiveness of aquatic exercise to treat fibromyalgia.
      included any sample size power calculations and that 3 of these
      • Foley A.
      • Halbert J.
      • Hewitt T.
      • Crotty M.
      Does hydrotherapy improve strength and physical function in patients with osteoarthritis—a randomised controlled trial comparing a gym based and a hydrotherapy based strengthening programme.
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      • Assis M.R.
      • Silva L.E.
      • Alves A.M.
      • et al.
      A randomized controlled trial of deep water running: clinical effectiveness of aquatic exercise to treat fibromyalgia.
      were based on pain outcomes. Five studies
      • Minor M.A.
      • Hewett J.E.
      • Webel R.R.
      • Anderson S.K.
      • Kay D.R.
      Efficacy of physical conditioning exercise in patients with rheumatoid arthritis and osteoarthritis.
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      • McIlveen B.
      • Robertson V.J.
      A randomised controlled study of the outcome of hydrotherapy for subjects with low back or back and leg pain.
      • Patrick D.L.
      • Ramsey S.D.
      • Spencer A.C.
      • Kinne S.
      • Belza B.
      • Topolski T.
      Economic evaluation of aquatic exercise for persons with osteoarthritis.
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      were independently powered to detect either a clinically meaningful or a conventionally large effect size for pain.
      • Angst F.
      • Aeschlimann A.
      • Stucki G.
      Smallest detectable and minimal clinically important differences of rehabilitation intervention with their implications for required sample sizes using WOMAC and SF-36 quality of life measurement instruments in patients with osteoarthritis of the lower extremities.
      • Farrar J.T.
      • Young Jr, J.P.
      • LaMoreaux L.
      • Werth J.L.
      • Poole R.M.
      Clinical importance of changes in chronic pain intensity measured on an 11-point numerical pain rating scale.
      • Cohen J.
      Statistical power analysis for the behavioral sciences.
      Table 2Quality Assessment of the 19 Studies Included in the Review Using Modified SIGN Criteria for RCTs
      StudyClear QuestionAcceptable Randomization MethodAdequate Concealment MethodBlinding of AssessorsGroups Similar at BaselineOnly Difference Between Groups Is Aquatic Exercise InterventionOutcomes Measurement: Standard, Valid, and Reliable?Percentage of Drop-Outs Before PosttestITTOverall Bias Rating
      Ahern et al
      • Ahern M.
      • Nicholls E.
      • Simionato E.
      • Clark M.
      • Bond M.
      Clinical and psychological effects of hydrotherapy in rheumatic diseases.
      WCWCNAAAPANRAANANA+
      Altan et al
      • Altan L.
      • Bingöl U.
      • Aykaç M.
      • Koç Z.
      • Yurtkuran M.
      Investigation of the effects of pool-based exercise on fibromyalgia syndrome.
      WCPANAWCWCPAWC
      • Gp1=4
      • Gp2=12
      NA
      Assis et al
      • Assis M.R.
      • Silva L.E.
      • Alves A.M.
      • et al.
      A randomized controlled trial of deep water running: clinical effectiveness of aquatic exercise to treat fibromyalgia.
      WCWCWCWCWCNAWC
      • Gp1=13.3
      • Gp2=14.8
      WC++
      Bilberg et al
      • Bilberg A.
      • Ahlmén M.
      • Mannerkorpi K.
      Moderately intensive exercise in a temperate pool for patients with rheumatoid arthritis: a randomized controlled study.
      AAAAAAAAWCNRAA
      • Gp1=0
      • Gp2=0
      NA+
      Cochrane et al
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      WCWCWCWCWCWCWC
      • Gp1=27.4
      • Gp2=24.5
      WC++
      Foley et al
      • Foley A.
      • Halbert J.
      • Hewitt T.
      • Crotty M.
      Does hydrotherapy improve strength and physical function in patients with osteoarthritis—a randomised controlled trial comparing a gym based and a hydrotherapy based strengthening programme.
      WCWCWCAAWCAAWC
      • Gp1=20
      • Gp2=25.7
      • Gp3=8.6
      WC++
      Green et al
      • Green J.
      • McKenna F.
      • Redfern E.J.
      • Chamberlain M.A.
      Home exercises are as effective as outpatient hydrotherapy for osteoarthritis of the hip.
      AAPANAPAPAPAPAOverall=25NA
      Gusi et al
      • Gusi N.
      • Tomas-Carus P.
      • Häkkinen A.
      • Häkkinen K.
      • Ortega-Alonso A.
      Exercise in waist-high warm water decreases pain and improves health-related quality of life and strength in the lower extremities in women with fibromyalgia.
      AANRNANAAANAAA
      • Gp1=5.5
      • Gp2=0
      NR
      Hall et al
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      WCWCAAAAWCAAWCOverall=6NA++
      Jentoft et al
      • Jentoft E.S.
      • Kvalvik A.G.
      • Mengshoel A.M.
      Effects of pool-based aerobic exercise on women with fibromyalgia/chronic widespread muscle pain.
      WCAANAWCWCWCWC
      • Gp1=18
      • Gp2=27
      NA+
      McIlveen and Robertson
      • McIlveen B.
      • Robertson V.J.
      A randomised controlled study of the outcome of hydrotherapy for subjects with low back or back and leg pain.
      AAPANAAAPAAAWC
      • Gp1=19.6
      • Gp2=5.6
      NA
      Minor et al
      • Minor M.A.
      • Hewett J.E.
      • Webel R.R.
      • Anderson S.K.
      • Kay D.R.
      Efficacy of physical conditioning exercise in patients with rheumatoid arthritis and osteoarthritis.
      AANRNANAWCWCAA
      • Gp1=14.9
      • Gp2=22
      • Gp3=12.5
      NA
      Patrick et al
      • Patrick D.L.
      • Ramsey S.D.
      • Spencer A.C.
      • Kinne S.
      • Belza B.
      • Topolski T.
      Economic evaluation of aquatic exercise for persons with osteoarthritis.
      WCWCNANApp
      The outcomes consisted of self-administered postal questionnaires only.
      WCWCWC
      • Gp1=16.8
      • Gp2=3.0
      WC++
      Rintala et al
      • Rintala P.
      • Kettunen H.
      • McCubbin J.A.
      Effects of a water exercise program for individuals with rheumatoid arthritis.
      WCAANANAAAAAAA
      • Gp1=5.5
      • Gp2=18.7
      NA
      Sjogren et al
      • Sjogren T.
      • Long N.
      • Storay I.
      • Smith J.
      Group hydrotherapy versus group land-based treatment for chronic low back pain.
      AAPANAAAAAAAAA
      • Gp1=6.7
      • Gp2=6.7
      NA
      Sutherland et al
      • Sutherland G.
      • Andersen M.B.
      • Stoové M.A.
      Can aerobic exercise training affect health-related quality of life for people with multiple sclerosis?.
      AANRNAPAAAAAAANAWC
      Sylvester
      • Sylvester K.L.
      Investigation of the effect of hydrotherapy in the treatment of osteoarthritic hips.
      AANRNAAAAAAAAA
      • Gp1=0
      • Gp2=0
      NA
      Wyatt et al
      • Wyatt F.B.
      • Milam S.
      • Manske R.C.
      • Deere R.
      The effects of aquatic and traditional exercise programs on persons with knee osteoarthritis.
      AANRNAAANAAAPAOverall=8.7NA
      Yozbatiran et al
      • Yozbatiran N.
      • Yildirim Y.
      • Parlak B.
      Effects of fitness and aquafitness exercises on physical fitness in patients with chronic low back pain.
      WCNANANAAAPAAANANA
      Abbreviations: AA, adequately addressed; Gp, group; ITT, intention-to-treat analysis (all subjects are analyzed in the groups to which they were randomly allocated); NA, not addressed; NApp, not applicable; NR, not reported; PA, poorly addressed; WC, well covered.
      Legends: +, some of the criteria have been fulfilled. Where they have not been fulfilled the conclusions of the study are thought unlikely to alter; ++, all or most of the criteria have been fulfilled. Where they have not been fulfilled the conclusions of the study are thought very unlikely to alter; −, few or no criteria fulfilled. The conclusions of the study are thought likely or very likely to alter.
      low asterisk The outcomes consisted of self-administered postal questionnaires only.

      Aquatic Exercise Versus No-Treatment Controls

      Of the 9 studies in this comparison,
      • Ahern M.
      • Nicholls E.
      • Simionato E.
      • Clark M.
      • Bond M.
      Clinical and psychological effects of hydrotherapy in rheumatic diseases.
      • Rintala P.
      • Kettunen H.
      • McCubbin J.A.
      Effects of a water exercise program for individuals with rheumatoid arthritis.
      • McIlveen B.
      • Robertson V.J.
      A randomised controlled study of the outcome of hydrotherapy for subjects with low back or back and leg pain.
      • Patrick D.L.
      • Ramsey S.D.
      • Spencer A.C.
      • Kinne S.
      • Belza B.
      • Topolski T.
      Economic evaluation of aquatic exercise for persons with osteoarthritis.
      • Sutherland G.
      • Andersen M.B.
      • Stoové M.A.
      Can aerobic exercise training affect health-related quality of life for people with multiple sclerosis?.
      • Foley A.
      • Halbert J.
      • Hewitt T.
      • Crotty M.
      Does hydrotherapy improve strength and physical function in patients with osteoarthritis—a randomised controlled trial comparing a gym based and a hydrotherapy based strengthening programme.
      • Bilberg A.
      • Ahlmén M.
      • Mannerkorpi K.
      Moderately intensive exercise in a temperate pool for patients with rheumatoid arthritis: a randomized controlled study.
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      • Gusi N.
      • Tomas-Carus P.
      • Häkkinen A.
      • Häkkinen K.
      • Ortega-Alonso A.
      Exercise in waist-high warm water decreases pain and improves health-related quality of life and strength in the lower extremities in women with fibromyalgia.
      5 were of moderate to high quality,
      • Ahern M.
      • Nicholls E.
      • Simionato E.
      • Clark M.
      • Bond M.
      Clinical and psychological effects of hydrotherapy in rheumatic diseases.
      • Patrick D.L.
      • Ramsey S.D.
      • Spencer A.C.
      • Kinne S.
      • Belza B.
      • Topolski T.
      Economic evaluation of aquatic exercise for persons with osteoarthritis.
      • Foley A.
      • Halbert J.
      • Hewitt T.
      • Crotty M.
      Does hydrotherapy improve strength and physical function in patients with osteoarthritis—a randomised controlled trial comparing a gym based and a hydrotherapy based strengthening programme.
      • Bilberg A.
      • Ahlmén M.
      • Mannerkorpi K.
      Moderately intensive exercise in a temperate pool for patients with rheumatoid arthritis: a randomized controlled study.
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      and of those, 3 had data suitable for incorporation into a meta-analysis
      • Patrick D.L.
      • Ramsey S.D.
      • Spencer A.C.
      • Kinne S.
      • Belza B.
      • Topolski T.
      Economic evaluation of aquatic exercise for persons with osteoarthritis.
      • Bilberg A.
      • Ahlmén M.
      • Mannerkorpi K.
      Moderately intensive exercise in a temperate pool for patients with rheumatoid arthritis: a randomized controlled study.
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      (fig 2A). This showed a small posttreatment effect in favor of aquatic exercise (P=.04; SMD=−.17; 95% CI, −.33 to −.01) (see fig 2A). Removing the smallest study
      • Bilberg A.
      • Ahlmén M.
      • Mannerkorpi K.
      Moderately intensive exercise in a temperate pool for patients with rheumatoid arthritis: a randomized controlled study.
      (n=22) from the analysis altered the SMD slightly from −.17 to −.19 (95% CI, −.35 to −.02) and the level of significance to P equal to .03. Statistical tests for heterogeneity were not significant. Qualitative analysis, based on review of results reported by researchers showed a lack of consistency between study results, whether of high or low quality. In summary, the evidence shows a small beneficial treatment effect in favor of aquatic exercise compared with no treatment. Only 1 study in the meta-analysis
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      independently showed an effect size in favor of pain relief (for WOMAC pain) that is clinically meaningful.
      • Angst F.
      • Aeschlimann A.
      • Stucki G.
      Smallest detectable and minimal clinically important differences of rehabilitation intervention with their implications for required sample sizes using WOMAC and SF-36 quality of life measurement instruments in patients with osteoarthritis of the lower extremities.
      However, the small number of good-quality studies that could be included into the meta-analysis and the inconsistency of results across all the studies suggest that, currently, we have insufficient evidence to categorically state that aquatic exercise is an effective modality for relieving pain.
      Figure thumbnail gr2
      Fig 2Meta-analysis of trials with moderate to low risk of bias. (A) Aquatic exercise versus no-treatment control group. (B) Aquatic exercise versus land-based exercise. The forest plots show the differences between aquatic exercise and no-treatment control groups and land exercise. Included are the means ± SD for each group, sample size, SMD, 95% CIs and the weighting for each study, and the combined results.

      Aquatic Exercise Versus Land Exercise

      Ten studies were identified in this comparison
      • Minor M.A.
      • Hewett J.E.
      • Webel R.R.
      • Anderson S.K.
      • Kay D.R.
      Efficacy of physical conditioning exercise in patients with rheumatoid arthritis and osteoarthritis.
      • Sylvester K.L.
      Investigation of the effect of hydrotherapy in the treatment of osteoarthritic hips.
      • Green J.
      • McKenna F.
      • Redfern E.J.
      • Chamberlain M.A.
      Home exercises are as effective as outpatient hydrotherapy for osteoarthritis of the hip.
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      • Sjogren T.
      • Long N.
      • Storay I.
      • Smith J.
      Group hydrotherapy versus group land-based treatment for chronic low back pain.
      • Jentoft E.S.
      • Kvalvik A.G.
      • Mengshoel A.M.
      Effects of pool-based aerobic exercise on women with fibromyalgia/chronic widespread muscle pain.
      • Wyatt F.B.
      • Milam S.
      • Manske R.C.
      • Deere R.
      The effects of aquatic and traditional exercise programs on persons with knee osteoarthritis.
      • Foley A.
      • Halbert J.
      • Hewitt T.
      • Crotty M.
      Does hydrotherapy improve strength and physical function in patients with osteoarthritis—a randomised controlled trial comparing a gym based and a hydrotherapy based strengthening programme.
      • Yozbatiran N.
      • Yildirim Y.
      • Parlak B.
      Effects of fitness and aquafitness exercises on physical fitness in patients with chronic low back pain.
      • Assis M.R.
      • Silva L.E.
      • Alves A.M.
      • et al.
      A randomized controlled trial of deep water running: clinical effectiveness of aquatic exercise to treat fibromyalgia.
      ; one of these was assessed as moderate quality
      • Jentoft E.S.
      • Kvalvik A.G.
      • Mengshoel A.M.
      Effects of pool-based aerobic exercise on women with fibromyalgia/chronic widespread muscle pain.
      and 3 as high quality.
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      • Foley A.
      • Halbert J.
      • Hewitt T.
      • Crotty M.
      Does hydrotherapy improve strength and physical function in patients with osteoarthritis—a randomised controlled trial comparing a gym based and a hydrotherapy based strengthening programme.
      • Assis M.R.
      • Silva L.E.
      • Alves A.M.
      • et al.
      A randomized controlled trial of deep water running: clinical effectiveness of aquatic exercise to treat fibromyalgia.
      Meta-analysis of the moderate- to high-quality studies with available data
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      • Jentoft E.S.
      • Kvalvik A.G.
      • Mengshoel A.M.
      Effects of pool-based aerobic exercise on women with fibromyalgia/chronic widespread muscle pain.
      showed no differences between aquatic exercise and land-based exercise (P=.56; SMD=.11; 95% CI, −.27 to .50) (see fig 2B). Data in the remaining 2 high-quality studies, reported as median and interquartile ranges for the WOMAC
      • Foley A.
      • Halbert J.
      • Hewitt T.
      • Crotty M.
      Does hydrotherapy improve strength and physical function in patients with osteoarthritis—a randomised controlled trial comparing a gym based and a hydrotherapy based strengthening programme.
      and pain VAS,
      • Assis M.R.
      • Silva L.E.
      • Alves A.M.
      • et al.
      A randomized controlled trial of deep water running: clinical effectiveness of aquatic exercise to treat fibromyalgia.
      are consistent with these findings. Of the poor-quality studies, only one
      • Wyatt F.B.
      • Milam S.
      • Manske R.C.
      • Deere R.
      The effects of aquatic and traditional exercise programs on persons with knee osteoarthritis.
      contradicts the overall consistency of results. In summary, the evidence—based on meta-analysis and overall consistency of results—suggests that aquatic exercise and land-based exercise have comparable pain-relieving effects.

      Aquatic Exercise Versus Immersion

      Two studies were identified in this comparison.
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      • Altan L.
      • Bingöl U.
      • Aykaç M.
      • Koç Z.
      • Yurtkuran M.
      Investigation of the effects of pool-based exercise on fibromyalgia syndrome.
      One of these was assessed as low quality
      • Altan L.
      • Bingöl U.
      • Aykaç M.
      • Koç Z.
      • Yurtkuran M.
      Investigation of the effects of pool-based exercise on fibromyalgia syndrome.
      ; meta-analysis of the data of these studies was therefore not performed. Neither study found any postintervention differences in pain outcomes between aquatic exercise and immersion groups. At present, the small number of good-quality studies hampers firm conclusions about the benefits of exercise in water versus immersion.

      Discussion

      Is Aquatic Exercise an Effective Treatment for Pain?

      When compared with no-treatment controls, meta-analysis shows a small but significant posttreatment effect in favor of hydrotherapy. The 95% CI for this effect comes close to, but does not cross, the line of no treatment effect. In 2 of the studies in the meta-analysis, exercise was performed in water ranging from 29.5° to 33.5°C
      • Patrick D.L.
      • Ramsey S.D.
      • Spencer A.C.
      • Kinne S.
      • Belza B.
      • Topolski T.
      Economic evaluation of aquatic exercise for persons with osteoarthritis.
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      ; temperature was described as “temperate” in one.
      • Bilberg A.
      • Ahlmén M.
      • Mannerkorpi K.
      Moderately intensive exercise in a temperate pool for patients with rheumatoid arthritis: a randomized controlled study.
      (p503) This encompasses a wide range of water temperature from cool to near thermoneutral (usually described as 34.5°–35°C). There is an assumption, by therapists and patients alike, that warmer water is more conducive to pain relief, and the mechanisms whereby heat alters pain perception are well known. Neuromuscular, hemodynamic, and metabolic responses to skin heating have been described
      • Bates A.
      • Hanson N.
      Aquatic exercise therapy.
      ; however, skin heating through whole-body immersion and core body temperature changes during exercise in water await investigation. The contribution of the warmth of the water to pain relief during hydrotherapy therefore remains speculative.
      Several researchers have also reported a relationship between water temperature and adherence, which suggests that thermal comfort is an important environmental factor in patients with a similar profile to those in the studies included in this review.
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      • Bunning R.D.
      • Masterton R.S.
      A rational program of exercise for patients with osteoarthritis.
      Our review found evidence that aquatic exercise has a small effect in relieving pain even at cooler temperatures below thermoneutral. Potentially, this has important implications in terms of water heating costs. In addition, it suggests that effective aquatic exercise can be practiced in community settings that traditionally maintain lower temperatures than hospital-based pools.
      Forty-two percent of studies in this review failed to cite water temperature and, because it is considered a critical variable, this should be reported in future aquatic exercise studies. Also, some studies fail to explicitly state the aim of the water-based exercise program and/or to provide an adequate description of its type and intensity (n=6 [31.5%]). The effect of exercise-induced analgesia on pain suggests that pain intensity is reduced after exercise.
      • Koltyn K.F.
      • Umerda M.
      Exercise, hypoalgesia and blood pressure.
      However, in humans, consistent results have been shown only for high-intensity land exercise (ie, ≥70% of maximal aerobic capacity). Exercise prescription is commonly based on predicted maximal heart rate because of the linear relationship between aerobic capacity and heart rate.
      • McArdle W.D.
      • Katch V.L.
      • Katch F.I.
      Energy generating capacities of humans.
      However, Tanaka et al
      • Tanaka H.
      • Monahan K.D.
      • Seals D.R.
      Age-predicted maximal heart rate revisited.
      have recently questioned the accuracy of exercise prescription based on predicted maximal heart rate, particularly in older people. Furthermore, the variable effect of water temperature on heart rate makes it uncertain that the exercise intensity in the studies reviewed was above the analgesic threshold.
      • Hall J.
      • Blake D.
      • Garbutt G.
      Acute physiological effects of exercise in water.
      The interaction between exercise intensity and water temperature, as well as having practical considerations,
      • Wilder R.P.
      • Brennan D.K.
      Aqua running.
      may affect pain differentially. In addition, water depth alters the nature of exercise through buoyancy and hydrostatic pressure. This in turn may influence the physiologic mechanisms underlying pain relief through the relationship between cardiovascular and pain regulatory pathways.
      • Bruehl S.
      • Chung O.Y.
      Interactions between the cardiovascular and pain regulatory systems: an updated review of mechanisms and possible alterations in chronic pain.
      The duration of the aquatic exercise program is another variable that may play a significant role in pain relief. In his review Janal
      • Janal M.N.
      Pain sensitivity, exercise and stoicism.
      highlights the uncertainty for the optimal duration of exercise-induced analgesia but suggests that the interaction between intensity and duration affects exercise-induced hypoalgesia. We noted that duration of treatment varied from twice a week for 4 weeks
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      to 4 times a week for 53 weeks.
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      The 3 studies
      • Patrick D.L.
      • Ramsey S.D.
      • Spencer A.C.
      • Kinne S.
      • Belza B.
      • Topolski T.
      Economic evaluation of aquatic exercise for persons with osteoarthritis.
      • Bilberg A.
      • Ahlmén M.
      • Mannerkorpi K.
      Moderately intensive exercise in a temperate pool for patients with rheumatoid arthritis: a randomized controlled study.
      • Cochrane T.
      • Davey R.C.
      • Matthes Edwards S.M.
      Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.
      comparing aquatic exercise and no-treatment controls are homogenous in terms of the type of exercise performed within the pool environment, but they have different durations of intervention, ranging from 12 to 52 weeks on a twice-weekly basis. It is interesting that those studies that do not report significant differences between groups are those of shorter duration. The duration of aquatic exercise programs for maximum pain relief is both clinically and economically important and warrants further investigation by good-quality longitudinal follow-up studies.

      How Does Aquatic Exercise Compare With Other Interventions?

      There is a general assumption that hydrotherapy will provide better pain relief than either land-based exercise or immersion alone. However, we found no significant differences between hydrotherapy and immersion in the 2 studies available.
      • Hall J.
      • Skevington S.M.
      • Maddison P.J.
      • Chapman K.
      A randomized and controlled trial of hydrotherapy in rheumatoid arthritis.
      • Altan L.
      • Bingöl U.
      • Aykaç M.
      • Koç Z.
      • Yurtkuran M.
      Investigation of the effects of pool-based exercise on fibromyalgia syndrome.
      In addition, no significant between-group differences were noted between aquatic and land-based exercise, which suggests that for those who find exercise on land challenging or tedious, exercise in water provides a similar effect. This lack of difference has been reported in previous studies,
      • Minor M.A.
      • Hewett J.E.
      • Webel R.R.
      • Anderson S.K.
      • Kay D.R.
      Efficacy of physical conditioning exercise in patients with rheumatoid arthritis and osteoarthritis.
      • Jentoft E.S.
      • Kvalvik A.G.
      • Mengshoel A.M.
      Effects of pool-based aerobic exercise on women with fibromyalgia/chronic widespread muscle pain.
      • Assis M.R.
      • Silva L.E.
      • Alves A.M.
      • et al.
      A randomized controlled trial of deep water running: clinical effectiveness of aquatic exercise to treat fibromyalgia.
      and currently, given the paucity of evidence, it is difficult to speculate which of the many variables (ie, temperature, exercise intensity and duration, treatment setting) could, either independently or in combination, be critical in pain relief. In contrast to our findings, the popularity of aquatic exercise as a modality for pain relief suggests that any additional benefits compared with land exercise have not yet been captured by the research.

      Features of This Review

      The impetus for this review was our perception of a disparity between anecdotal reports of significant pain relief from aquatic exercisers and our informal reading of the literature. Thus we chose to focus on the outcome, pain, rather than a specific population. In focusing on pain, we made an a priori selection of the primary pain outcome measure based on the availability of raw data and the most frequently occurring measure across all studies when multiple outcomes for this variable were cited. The lack of consistency in pain outcome measurements across the studies validated our decision to limit our definition to pain intensity; future reviews might be able to incorporate evaluations of pain behavior and cognitive coping strategies as prospective studies include such measures. We selected the RCT checklist produced by SIGN, one of many quality assessment tools, which allows overall assessment of individual components and is included in best practice systems reported by the Agency for Healthcare Research and Quality. However, as Katrak et al
      • Katrak P.
      • Bialocerkowski A.E.
      • Massy-Westropp N.
      • Kumar S.
      • Grimmer K.A.
      A systematic review of the content of critical appraisal tools.
      point out, there is no criterion standard for quality assessment tools in allied health research, and so our results must be considered in the light of the instrument we used.

      Key Recommendations for Future Research in Hydrotherapy

      We noted a number of substantial research design issues with 57.8% of the studies having important methodologic flaws. Most of these flaws related to aspects of RCT design such as randomization, allocation concealment, and blinding to outcome measurement. In addition, inadequate reporting of the intervention—in terms of setting, water temperature, depth, aim, type, and intensity of exercise—meant that some studies may have been downgraded as a result of poor reporting. Jüni et al
      • Jüni P.
      • Altman D.G.
      • Egger M.
      Assessing the quality of randomised controlled trials.
      defend this “guilty until proven innocent” argument with the justification that faulty reporting generally reflects poor methodology. Lack of resources meant that we were unable to contact researchers for further information. We acknowledge the impossibility of patient blinding to aquatic exercise; however, other approaches such as blinding of patients to the research hypothesis and evaluation of the expectations of patients and practitioners are possible and may be particularly important for pain and other self-reported outcome.
      • Crowe R.
      • Gage H.
      • Hampson S.
      • Hart J.
      • Kimber A.
      • Thomas H.
      The role of expectancies in the placebo effect and their use in the delivery of health care: a systematic review.
      • Quinn F.
      • Hughes C.
      • Baxter D.G.
      Complementary and alternative medicine in the treatment of low back pain: a systematic review.
      Many of the studies included in this review were general studies of aquatic exercise effectiveness that lacked a primary outcome measure, appropriate power, and adequate follow-up periods. Future studies should address these deficits by including specific details of the intervention, careful and creative consideration of both RCT design and of the literature on minimum clinically important differences for the primary outcome of interest (eg, for pain
      • Angst F.
      • Aeschlimann A.
      • Stucki G.
      Smallest detectable and minimal clinically important differences of rehabilitation intervention with their implications for required sample sizes using WOMAC and SF-36 quality of life measurement instruments in patients with osteoarthritis of the lower extremities.
      • Farrar J.T.
      • Young Jr, J.P.
      • LaMoreaux L.
      • Werth J.L.
      • Poole R.M.
      Clinical importance of changes in chronic pain intensity measured on an 11-point numerical pain rating scale.
      • Robinson V.
      • Boers M.
      • Brooks P.
      • et al.
      Patient-reported pain is central to OMERACT rheumatology core measurement sets.
      ), and comprehensive reporting based on current recommendations.
      • Moher D.
      • Schulz K.F.
      • Altman D.G.
      CONSORT Group (Consolidated Standards of Reporting Trials)
      The CONSORT statement: revised recommendations for improving the quality of reports of parallel-group randomized trials.
      We noted, as did Geytenbeek,
      • Geytenbeek J.
      Evidence for effective hydrotherapy.
      that aquatic exercise research concentrates almost exclusively on chronic musculoskeletal conditions. However, the increasing use of aquatic exercise for patients with neurologic disorders suggests that this area is ripe for research.
      • Hurley R.
      • Turner C.
      Neurology and aquatic therapy.
      • Morris D.M.
      Aquatic rehabilitation for the treatment of neurological disorders.
      Finally, given the importance of predicting patient outcome, data analysis on the basis of improvement versus deterioration and adherence versus nonadherence is also recommended.

      Conclusions

      In contrast to anecdotal reports of superior pain relief from aquatic exercise, our review shows that water and land-based exercise are similar, although when compared with no treatment, exercise in water provides limited analgesia. Inconsistent results in studies with no-treatment comparison groups combined with the design flaws and reporting omissions throughout the studies reviewed suggests that large, pragmatic studies are required to establish the optimal combinations of exercise type, duration, water temperature and depth, and service delivery for diverse patient populations. Furthermore, discrepancy between the perceived value of hydrotherapy in clinical practice and our findings justifies future research endeavors.
      Supplier
      aRevMan, version 4.2.9; Cochrane Collaboration, Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe St, Mail Rm W5010, Baltimore, MD 21205.

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