Effectiveness of aquatic exercise for musculoskeletal conditions

The following research the aquatic exercise and musculoskeletal conditions is from Anna Barker, Jason Talevski, Renata Morello and Caroline Brand, Health Services Research Unit, Centre of Research Excellence in Patient Safety, Division of Health Services and Global Health Research, Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC and Melbourne EpiCentre, University of Melbourne, Melbourne, VIC; Ann Rahmann, Division of Physiotherapy, School of Health and Rehabilitation Sciences, University of Queensland, St Lucia, QLD and Brighton Health Campus, Metro North Hospital and Health Service, Brisbane, QLD; Donna Urquhart, Musculoskeletal Unit, Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia; and was published in 2014 by Archives of Physical Medicine and Rehabilitation (American Congress of Rehabilitation Medicine).

Abstract

Objective: To investigate the effectiveness of aquatic exercise in the management of musculoskeletal conditions.

Data Sources: A systematic review was conducted using Ovid MEDLINE, Cumulative Index to Nursing and Allied Health Literature, Embase, and The Cochrane Central Register of Controlled Trials from earliest record to May 2013.

Study Selection: We searched for randomized controlled trials (RCTs) and quasi-RCTs evaluating aquatic exercise for adults with musculoskeletal conditions compared with no exercise or land-based exercise.

Outcomes of interest were pain, physical function, and quality of life.

The electronic search identified 1199 potential studies. Of these, 1136 studies were excluded based on title and abstract. A further 36 studies were excluded after full text review, and the remaining 26 studies were included in this review.

Data Extraction: Two reviewers independently extracted demographic data and intervention characteristics from included trials. Outcome data, including mean scores and SDs, were also extracted.

Data Synthesis: The Physiotherapy Evidence Database (PEDro) Scale identified 20 studies with high methodologic quality (PEDro score ≥ 6).

Compared with no exercise, aquatic exercise achieved moderate improvements in pain (standardized mean difference [SMD]=-.37; 95% confidence interval [CI], -.56 to -.18), physical function (SMD=.32; 95% CI, .13e.51), and quality of life (SMD=.39; 95% CI, .06e.73).

No significant differences were observed between the effects of aquatic and land-based exercise on pain (SMD=-.11; 95% CI, -.27 to .04), physical function (SMD=-.03; 95% CI, -.19 to .12), or quality of life (SMD=-.10; 95% CI, -.29 to .09).

Conclusions: The evidence suggests that aquatic exercise has moderate beneficial effects on pain, physical function, and quality of life in adults with musculoskeletal conditions.

These benefits appear comparable across conditions and with those achieved with land-based exercise.

Further research is needed to understand the characteristics of aquatic exercise programs that provide the most benefit.

Woman with musculoskeletal conditions and neck pain.

Introduction

Musculoskeletal conditions are widespread and among the world’s leading causes of chronic pain, disability, and reduced health related quality of life.

A recent report on global burden of disease highlighted that musculoskeletal conditions account for 7% of total disability-adjusted life years, with low back pain accounting for nearly half, and osteoarthritis accounting for almost 10% of this burden.

Musculoskeletal conditions are also the most common cause for using health care resources.

This burden, reflected by endorsement of the Bone and Joint Decade 2000-2010 by the United Nations and World Health Organization, is predicted to rise because of the aging population.

As such, identifying and promoting effective management strategies for these conditions has been flagged as a public health priority.

There is a growing body of evidence that suggests that aquatic exercise can decrease the disease burden of musculoskeletal conditions.

The benefits of aquatic exercise arise from the physiological effects of immersion and hydrodynamic principles of exercise in the aquatic environment.

Buoyancy decreases compressive weight-bearing stresses on joints and allows functional exercise with lessened gravitational load, improving both strength and range of movement.

Additionally, immersion in thermoneutral water (34º C) decreases sympathetic nervous system activity, which in combination with the compressive effects of hydrostatic pressure can reduce swelling and perception of pain in people with musculoskeletal conditions.

The aquatic environment can allow higher-intensity exercises to be undertaken, with lower cardiovascular stress than is possible on land.

Despite the increasing number of randomized controlled trials (RCTs) being undertaken, the most recent Cochrane systematic review published in 2007, limited to osteoarthritis studies, concluded that there remains a lack of high-quality studies in this area.

The meta-analysis included data from 6 randomized controlled trials and identified that aquatic exercise had a small-to-moderate short-term effect on pain, function, and quality of life compared with no intervention.

A more recent meta-analysis published in 2011 focused only on function, mobility, and pooled health outcomes in people with osteoarthritis or rheumatoid arthritis.

This review included 10 RCTs and concluded that aquatic exercise had comparable effects with land-based exercise.

This review again highlighted the variability in methodologic quality of included studies, hindering the identification of true differences between the 2 modes of exercise.

Reviews completed on the effects of aquatic exercise for people with fibromyalgia, and low back pain have also reported positive impacts with aquatic exercise; however, they were cautious in their conclusions because of variable study quality.

Although there is evidence that aquatic exercise is an effective strategy in the management of a number of musculoskeletal conditions, the relative benefits across conditions have not been reported because previous reviews have only focused on individual conditions.

Therefore, the aims of this review were (1) to systematically examine the effect of aquatic exercise on pain, physical function, and quality of life in people with musculoskeletal conditions when compared with both no exercise and land-based exercise; and (2) investigate the relative effectiveness of aquatic exercise for individual musculoskeletal conditions, including osteoarthritis, rheumatoid arthritis, fibromyalgia, low back pain, and osteoporosis.

Methods

Literature search:

A systematic search of literature was conducted until May 2013.

Ovid MEDLINE, Cumulative Index to Nursing and Allied Health Literature, Embase, and The Cochrane Central Register of Controlled Trials were searched to identify published research.

A sensitive search strategy was developed using medical subject heading search terms and keywords (appendix 1) and translated for each database as appropriate.

Appendix 1: Search strategy of musculoskeletal conditions.

The references of included studies were also reviewed for further relevant literature.

Eligibility criteria

Study selection:

Two reviewers independently screened and excluded studies based on title and abstracts.

For articles not excluded by this process, full text was obtained and assessed independently by both reviewers against the inclusion and exclusion criteria.

If a decision could not be reached between the 2 reviewers, a third reviewer was called for the final decision.

Types of studies and participants:

Studies were included if they were conducted as a randomized controlled trials or quasi- RCT.

Participants had to be diagnosed with at least 1 musculoskeletal condition using accepted arthritis and musculoskeletal diagnostic criteria.

Studies with participants <18 years of age or who had recently had surgery (eg, arthroplasty, spinal surgery) were excluded.

Interventions:

Studies must have included 1 group that participated in aquatic exercise and a comparison group that participated in no exercise (including nonactive activities [eg, education]) or land-based exercise.

Aquatic exercise interventions were defined as any type of endurance, flexibility, strength, resistance, or aerobic exercise conducted in a pool.

Other hydrotherapy methods, such as turbulent spa therapy and balneotherapy (immersion in mineralized water), were excluded because these approaches do not usually include an active exercise component.

Outcomes:

Outcomes of interest were pain, physical function, and quality of life.

To be included in this review, studies had to have reported outcome measures known to be responsive for measuring change in pain, physical function, or quality of life in people with musculoskeletal conditions.

When 2 outcome measures were available for the same outcome, only 1 was included in the meta-analysis.

Generic (nondisease) outcome measures were prioritized for inclusion in the meta-analysis followed by disease-specific measures based on priority lists defined by a prior Cochrane systematic review.

Outcome measures were also required to be scored on a 0 to 100 scale or have the capability to be converted to this scale.

The list of outcome measures that met the inclusion criteria is shown in table 1 in descending order of priority.

Table 1: Outcome measures eligible included meta-analysis.

Table 1: Abbreviations musculoskeletal conditions.

Methodologic quality assessment

All included studies were assessed for methodologic quality independently by 2 reviewers using the Physiotherapy Evidence Database (PEDro) Scale.

This scale rates 11 aspects of methodologic quality of RCTs as being either absent or present (appendix 2). Because the first item (eligibility criteria) is not scored, the total score ranges from 0 to 10.

Appendix 2: PEDro scale items of musculoskeletal conditions.

Studies that obtain a score of <6 points are considered low quality, whereas those with a score ≥6 points are considered high quality.

A third reviewer was called if consensus could not be reached.

Data extraction:

Two reviewers independently extracted data for the included studies.

Demographic data (age, sex, musculoskeletal condition) and intervention characteristics (exercise components, duration, frequency) were extracted from included trials.

Outcome data, including mean scores, SDs, and sample sizes, were also extracted for 2 time points: baseline (preintervention) and first follow-up (postintervention) assessment.

When necessary, the SD was approximated by dividing the interquartile range by 1.35, and medians were used as the best estimates of means.

Statistical analysis:

A meta-analysis was conducted using pooled data and described as standardized mean differences (SMDs) and 95% confidence intervals (CIs).

This method is useful for comparing data collected using different scales.

Heterogeneity between trials was assessed using the I2 statistic.

Statistical heterogeneity was considered substantial if I2 was >50% (heterogeneous).

In this event a random effects model was applied; otherwise, a fixed-effects model was used.

Outcome data were excluded from the meta-analysis if there were significant differences in baseline scores of the outcome of interest to ensure that the SMD in postintervention scores was not confounded.

An SMD <0.2 was considered a small effect, an SMD between 0.2 and 0.8 was considered a moderate effect, and an SMD >0.8 was considered a large effect.

Scale directions were aligned by adding negative values where required.

A separate meta-analysis was run for each outcome and comparator options.

For each meta-analysis, a secondary analysis was conducted that excluded studies of low methodologic quality (PEDro score <6); therefore, estimates of effect could be established that avoided distortion probable from inclusion of findings from low-quality studies.

All meta-analyses were performed using RevMan 5.2 software.

Results

Search yield:

The electronic search identified 1199 potential studies for screening of eligibility after duplicate studies were removed.

Of these, 1136 studies were excluded based on title and abstract.

The full text was obtained for the remaining 63 studies.

Based on the reviewer’s decisions, 36 studies were excluded after full text review because they did not meet inclusion criteria (appendix 3).

Appendix 3: List excluded studies after reading full text of musculoskeletal conditions.

A total of 26 studies were included in the review (fig 1).

Figure 1: Flowchart studies of musculoskeletal conditions.

Description of included studies:

The 26 included studies consisted of 24 randomized controlled trials and 2 quasi- RCTs in osteoarthritis, rheumatoid arthritis, fibromyalgia, low back pain, and osteoporosis populations.

Most studies (n=16; 62%) included participants with osteoarthritis.

Eighteen studies compared aquatic exercise with no exercise; 15 studies compared aquatic exercise with some form of land based exercise, and 7 studies included both no exercise and land-based exercise comparisons.

Participants were typically older, with 16 studies including participants with a mean age >60 years (table 2).

Table 2: Characteristics studies of musculoskeletal conditions.

Methodologic quality:

Methodologic quality was independently assessed by 2 reviewers.

A third reviewer was required to assess the methodologic quality for 5 studies because the first 2 reviewers could not reach a consensus.

The median score for methodologic quality using the PEDro Scale was 6 out of 10 (range, 4-8), indicating that studies were of high quality.

Twenty studies were assessed as being high quality (PEDro score ≥6) (see table 2).

Common methodologic limitations identified across studies included omission of reporting if analysis was performed on an intention-to-treat basis and whether allocation was concealed.

Aquatic exercise program characteristics

Aquatic exercise programs varied substantially across the included studies in terms of total intervention duration (range, 3-52wk), frequency (range, 1-7 times per wk), and class duration (range, 30-60min) (see table 2).

Variability was also observed for the types of exercises included in programs; however, it was common for programs to include warm-up, strength, stretching, range of motion, aerobic, and cool-down exercises.

Effects of interventions

Most studies reported on pain (n=25; 96%) and physical function outcomes (n=24; 92%) (see table 2).

For physical function and quality of life outcomes, positive scores indicated improved health, whereas for pain outcomes, negative scores indicated improved health (ie, reduction in pain).

All studies reported SD values; therefore, no approximations of these values were required.

Pain:

Fifteen studies were included in the meta-analysis of pain outcomes for aquatic exercise compared with no exercise. There was significant heterogeneity detected for the studies (I2=53%).

When a random-effects analysis was applied, aquatic exercise compared with no exercise achieved a moderate reduction in pain (SMD=-.37; 95% CI, -.56 to -.18).

Effects were comparable across osteoarthritis, rheumatoid arthritis, fibromyalgia, and low back pain populations (test for subgroup differences; P=.07) (fig 2A).

Figure 2A: Meta-analysis pain outcomes aquatic exercise.

When the meta-analysis was repeated excluding low-methodologic-quality studies, there was no appreciable difference in the effect on pain (SMD=-.33; 95% CI, -.53 to -.13).

Ten studies were included in the meta-analysis of pain outcomes for aquatic exercise compared with land-based exercise.

There was no significant heterogeneity detected for the studies (I2=50%).

When a fixed-effects analysis was applied, aquatic exercise compared with land-based exercise achieved a small nonsignificant reduction in pain (SMD=-.11; 95% CI, -.27 to .04).

Effects on pain were comparable across osteoarthritis, rheumatoid arthritis, fibromyalgia, and low back pain populations (test for subgroup differences; P=.08) (fig 2B).

Figure 2B: Meta-analysis pain outcomes aquatic exercise.

When the meta-analysis was repeated excluding low-methodologic-quality studies, no appreciable difference was found (SMD=-.08; 95% CI, -.27 to .09).

Physical function:

Fourteen studies were included in the meta-analysis of physical function outcomes for aquatic exercise compared with no exercise.

Significant heterogeneity was detected for these studies (I2=53%).

When a random-effects analysis was applied, aquatic exercise compared with no exercise controls achieved a moderate improvement in physical function (SMD=.32; 95% CI, .13-.51), and effects were comparable across osteoarthritis, rheumatoid arthritis, and fibromyalgia populations.

There was some evidence of a difference of effects across the included condition types with the 1 study conducted in people with osteoporosis favoring the no exercise control group (test for subgroup differences; P=.02).

No studies were included that reported on physical function outcomes in low back pain population (fig 3A).

Figure 3A: Meta-analysis of physical function outcomes aquatic exercise.

When the meta-analysis was repeated excluding low-methodologic quality studies, there was no appreciable difference in the effect on physical function (SMD=.28; 95% CI, .09-.42).

Ten studies were included in the meta-analysis of physical function outcomes for aquatic exercise compared with land-based exercise.

There was no significant heterogeneity detected for the studies (I2=38%).

Applying a fixed-effects analysis, aquatic exercise compared with land-based exercise achieved comparable effects on physical function (SMD=-.03; 95% CI, -.19 to .12), and this effect was consistent across all populations (test for subgroup differences; P=.10) (fig 3B).

Figure 3B: Meta-analysis of physical function outcomes aquatic exercise.

When the meta-analysis was repeated excluding low-methodologic-quality studies, there was no appreciable difference in the effect on physical function (SMD=-.04; 95% CI, -.20 to .12).

Quality of life:

Eleven studies were included in the meta-analysis of quality of life outcomes for aquatic exercise compared with no exercise.

Significant heterogeneity was detected for the studies (I2=78%).

When a random-effects analysis was applied, aquatic exercise achieved moderate improvements in quality of life compared with no exercise controls (SMD=.39; 95% CI, .06-.73).

There was some evidence of a difference of effects across the included condition types (test for subgroup differences; P=.02).

Although a moderate improvement in quality of life was observed in studies conducted in osteoarthritis populations, small nonsignificant effects were observed in the osteoporosis and rheumatoid arthritis populations in favor of the no exercise control group (fig 4A).

Figure 4A: Meta-analysis of quality of life outcomes aquatic exercise.

However, this finding was limited to only 1 study in each population.

When the meta-analysis was repeated excluding low-methodologic-quality studies, there was no appreciable difference in the effect.

Seven studies were included in the meta-analysis of quality of life outcomes for aquatic exercise compared with land-based exercise.

No significant heterogeneity was detected for the studies (I2=12%).

When a fixed-effects model analysis was applied, aquatic exercise compared with land-based exercise achieved comparable improvements in quality of life (SMD=-.10; 95% CI, -.29 to .09).

These effects were consistent across osteoarthritis and osteoporosis populations (test for subgroup differences; P=.47).

There were no studies that reported on quality of life outcomes that compared aquatic exercise with land-based exercise in fibromyalgia or low back pain populations.

All studies reporting on quality of life were of high methodologic quality (fig 4B).

Figure 4B: Meta-analysis of quality of life outcomes aquatic exercise.

Discussion

This review provides new evidence that aquatic exercise provides moderate benefits to people with musculoskeletal conditions reflected in reduced pain and improved physical function and quality of live.

These results are consistent with prior reviews that focused on individual musculoskeletal conditions in isolation. Improvements in pain and physical function were observed to be mostly consistent across different musculoskeletal conditions.

Importantly, these results persisted when low-quality studies were removed from analysis.

Compared with land-based exercise, aquatic exercise achieved equivalent improvements in all outcomes.

This indicates that patients can choose the exercise mode that appeals most to them.

This is an important finding because the provision of patient choice in treatment interventions is known to improve patient outcomes and participation, which is a critical factor to intervention effectiveness.

Even if an intervention is effective, if it is not accepted by the target population it is of little benefit.

A review of exercise participation among people with osteoarthritis found that poor participation is the most compelling explanation for the declining impact of the benefits of exercise over time.

Several of the studies in this review observed higher participation levels in aquatic exercise compared with land-based exercise groups.

Future studies should aim to explore patient preferences for aquatic exercise compared with land-based exercise and the relative long-terms effects of aquatic exercise.

Musculoskeletal conditions are not mutually exclusive.

The pathophysiology of each disorder differs between each condition.

Despite this difference, musculoskeletal conditions share a range of associated symptoms, including pain, fatigue, and difficulties with activities of daily living.

Prior reviews have sought to establish the effectiveness of aquatic exercise with an individual focus on 1 musculoskeletal condition, failing to find the potential differential effects of aquatic exercise across multiple musculoskeletal conditions.

To our knowledge, this is the first meta-analysis conducted across different musculoskeletal conditions.

Our results have provided precise pooled estimates of treatment effects of aquatic exercise across multiple musculoskeletal conditions, including osteoarthritis, rheumatoid arthritis, fibromyalgia, low back pain, and osteoporosis.

Meta-analysis results showed benefits were mostly consistent across condition types.

Improvements in pain were consistent across the different musculoskeletal conditions; however, the reduction in pain for rheumatoid arthritis and low back pain populations was nonsignificant.

This may be an artifact of only 1 study’s being included for each of these populations; therefore, meta-analysis of effects for these condition subgroups could not be performed.

Improvement in physical function was consistent across osteoarthritis, rheumatoid arthritis, and fibromyalgia populations in studies that compared aquatic exercise with no exercise.

However, when compared with land-based exercise, this effect was lost in the osteoarthritis and fibromyalgia populations.

No improvements were observed for physical function in the osteoporosis population when compared with either no exercise or land-based exercise.

There were a limited number of studies in low back pain, rheumatoid arthritis, osteoporosis, and fibromyalgia populations; therefore, the differential effects noted across conditions must be interpreted with caution.

Further studies and analysis are required to more accurately determine differential effects across different musculoskeletal conditions.

The data on quality of life were rarely reported in studies despite being an important outcome for people with musculoskeletal conditions.

People participating in aquatic exercise often report an enhanced sense of well-being. Impacts on quality of life were investigated in osteoarthritis, rheumatoid arthritis, and osteoporosis populations, and positive effects in the aquatic exercise group were reported for only osteoarthritis studies.

The effect of aquatic exercise on quality of life for other musculoskeletal conditions (fibromyalgia, low back pain) remains uncertain and needs further investigation.

Quality of life outcomes should be included in future studies investigating the effect of aquatic exercise for people with musculoskeletal conditions.

There was considerable variability among the aquatic exercise programs used in each study.

Disappointingly, many studies supplied limited details on the types of exercise, dose, and intensity included in the aquatic exercise intervention.

This made comparisons between studies and identification of characteristics of the most beneficial programs difficult.

Based on this review, further research is required to investigate the characteristics of aquatic exercise programs that provide the most beneficial results.

Study limitations

Only RCTs published in English were included; therefore, potentially relevant high-quality studies with different designs or in other languages may have been excluded.

In addition, searches were limited to published studies.

Because there is a tendency for editors to publish studies with positive findings, this review may be subject to publication bias.

We found a high heterogeneity and wide CIs of most effect sizes and variability in study quality and exercise interventions (frequency, types of exercise), which may have contributed random error to outcomes.

Also of note, the aim of this literature review was to explore the benefits of aquatic exercise in several different musculoskeletal clinical groups in the peer review literature.

As such, this review was undertaken with a broad exploratory focus and pooled studies of different musculoskeletal conditions with different pathophysiology.

However, we avoided this issue by also looking at different subgroup effects.

This potential limitation needs to be acknowledged when considering the review findings.

Conclusions

Overall, the studies included in this review were of high quality and demonstrate that aquatic exercise can have positive effects on pain, physical function, and quality of life for adults with musculoskeletal conditions.

However, there is further need for large-scale trials of sufficient duration and adequate follow-up period to validate the long-term effects of aquatic exercise.

In addition, future trials need to examine different modes, frequency, intensity, and participation in aquatic exercise programs so the characteristics of programs that achieve maximum benefits are well understood.

Woman with musculoskeletal conditions, doing Kaenz aquatic exercise in swimming pool.

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