Fibromyalgia Syndrome (FMS) is a rheumatic disease of unknown etiology [
There is evidence from randomized controlled trials (RCTs) that some treatments, for example, pharmacotherapy, patient education, behavioral therapy, and physiotherapy, are effective in reducing symptoms [
The aims of TE include the prevention of dysfunction and the development, restoration, or maintenance of strength, aerobic resistance, mobility, flexibility, coordination, balance, and functional abilities [
Methods used in TE include aerobic training, coordination and balance training, posture stabilization, body mechanics, flexibility exercises, gait training, relaxation techniques, and muscle strengthening exercises [
The aim of this meta-analysis was to summarize evidence on the effectiveness of therapeutic exercise in FMS.
This review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement [
A systematic review of publications retrieved from the Cochrane Plus, PEDro, and Pubmed databases was performed. A manual search of the journals FisioterapiaandCuestiones de Fisioterapia was also carried out. The search strategy is detailed in Additional File (see Supplementary Material available online at
The search was conducted by two authors (DS, SN) who screened the titles and abstracts of potentially eligible studies. DS and SN also independently examined the full text of articles which passed the initial screening in order to determine whether they met the selection criteria. Cases where there was a discrepancy between the two reviewers were reevaluated and a consensus decision was achieved by discussion.
RCTs comparing types of therapeutic exercise or comparing therapeutic exercise with a control group receiving another intervention or standard care were included.
Studies with participants older than 18 years, diagnosed with FMS in the absence of significant comorbidity, were included.
Studies using aerobic, strengthening, or stretching exercises or a combination of these were considered. Studies of exercise interventions based on activities such as yoga or tai-chi were excluded.
All included studies compared the effect of at least one type of exercise with a control treatment, either another form of physical activity or standard care.
All included studies assessed at least one key domain of FMS symptoms (pain; symptoms of depression; global well-being; health-related quality of life (HRQOL)).
Two authors (DS, TG) extracted the data independently using standard extraction forms. Data collected included participants, sample sizes, duration of studies, interventions, outcomes, results, and methods to measure outcomes. Discrepancies were rechecked and consensus was achieved by discussion.
Data extracted after treatment were considered an experimental group and values presented by the patients before treatment as a control group. When two different treatments were compared in the same study they were treated as independent studies for the purposes of the meta-analysis, because the aim of this study was to compare the effects of various therapies.
On the other hand, for each variable two subgroups were differentiated depending on whether the analysis by intention-to-treat or per protocol was performed in the study. When standard deviations (SDs) were not reported in the publication, they were calculated based on what was published from
The following items were extracted: author/year, design of the study, participants, interventions, comparisons, outcomes studied in this meta-analysis, and conclusions.
When researchers reported more than one indicator for an outcome a predefined order of preference for analysis was used. These preferences were predefined according to the specificity of each outcome measure (in descending order):
Two pairs of reviewers (DS, SN and TG, DP) worked independently to assess the methodological quality in accordance with the CONSORT 2010 [
The meta-analysis was conducted using the Review Manager Analysis software (RevMan 5.3) from the Cochrane Collaboration. Standardized mean differences (SMDs) were calculated from the means and SMDs for each intervention. The SMD used in RevMan software is the measure of effect size known as Hedge’s (adjusted)
The combined results were assessed using a random effects model, which is more conservative than a fixed effects model and incorporates both within- and between-study variance. Cohen’s
Heterogeneity was assessed using the
In the random effects model tau2 (
In order to examine the influence of individual studies on the overall results, pooled analyses were conducted with each study individually deleted from the model. This enabled us to investigate causes of heterogeneity [
The effects of the various types of exercise (aerobic, strengthening, stretching, and combined) were also analyzed separately.
Potential publication bias was assessed by visually inspecting the funnel plot (plots of effect estimates against standard error) produced by the RevMan Analysis software. Publication bias tends to result in asymmetrical funnel plots [
The literature search produced 704 citations, of which 262 were double hits (studies found in at least two data sources). Screening of title and abstracts resulted in exclusion of 393 studies. After reading the full text of the remaining articles, 33 studies were excluded. 16 RCTs were included in the qualitative synthesis, but only 14 were included in the quantitative analyses because the required measures were not available for 2 studies (Figure
Flow diagram of procedure for selection of studies.
General characteristics of included studies are detailed in Table
General characteristics of included studies.
Author/year | Design | Participants | Intervention/comparison | Outcomes | Conclusions |
---|---|---|---|---|---|
Wigers et al. 1996 [ |
RCT | AE: 18 women and 2 men |
|
(i) Pain |
Aerobic exercise was the overall most effective treatment. |
|
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Jones et al. 2001 [ |
RCT | EG: 28 women with FMS |
|
(i) Pain |
Muscle strengthening produces an improvement in overall disease activity. |
|
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Richards and Scott |
RCT | EG: 62 women and 5 men |
|
(i) FMS impact | Aerobic exercise is an effective treatment for FMS. |
|
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Rooks et al. 2007 [ |
RCT | AE: 35 women with FMS |
|
(i) Pain |
Progressive walking, simple strength training movements, and stretching activities improve functional status, key symptoms, and self-efficacy in women with FMS. |
|
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Bircan et al. 2008 [ |
RCT | AE: 13 women with FMS |
|
(i) Pain |
AE and SE are similarly effective at improving symptoms, depression, and quality of life in FMS. |
|
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García-Martínez et al. 2010 [ |
RCT | EG: 14 women with FMS |
|
(i) Pain |
The GE improved quality of life, psychological state, and physical functioning. |
|
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Sañudo et al. 2010 [ |
RCT | EG1: 22 women with FMS |
|
(i) FMS impact |
An improvement from baseline in total FIQ score was observed in the exercise groups and was accompanied by decreases in BDI scores. Relative to nonexercising controls, CE evoked improvements in the SF-36 physical functioning and bodily pain domains and was more effective than AE for evoking improvements in the vitality and mental health. |
|
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Mannerkorpi et al. |
RCT | EG: 34 women with FMS |
|
(i) Pain |
The Nordic walking group had better FIQ physical scores. |
|
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Sañudo et al. 2011 [ |
RCT | EG: 18 women with FMS |
|
(i) HRQOL |
A combined program of long-term exercise improves psychological and health status by increasing the quality of life. |
|
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Kayo et al. 2012 [ |
RCT | WPG: 30 women with FMS |
|
(i) Pain |
Both modalities (WP and PSM) provided better pain relief for people with FMS than medication only or conventional treatment. |
|
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Hooten et al. 2012 [ |
RET | AE: 32 women and 4 men |
|
(i) Pain severity | Strengthening exercises and aerobic exercise are similarly effective in reducing pain intensity. |
|
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Gavi et al. 2014 [ |
RCT | MSE: 35 women with FMS |
|
(i) Pain |
Both groups experienced a reduction in pain, which was more noticeable and had an earlier onset in the strengthening exercise group. Both groups experienced improvements in functionality, depression, and quality of life. |
|
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Duruturk et al. 2015 [ |
RCT | BE: 12 women with FMS |
|
(i) Pain |
Both groups showed an improvement in pain intensity and FIQ functionality; there was no group difference on either measure. |
|
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Larsson et al. 2015 [ |
RCT | RE: 67 women with FMS |
|
(i) HRQOL |
Resistance exercise group reduced pain intensity. |
|
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Ericsson et al. 2016 [ |
RCT | EG: 67 women with FMS |
|
(i) Pain |
Resistance exercise improves some symptoms in women with FMS. |
RCT: randomized clinical trial; RET: randomized equivalence trial; EG: exercise group; CG: control group; FMS: Fibromyalgia Syndrome.
The number of groups compared in the studies varied: one study compared four groups (two exercise groups, one self-help course group, and a combination of exercise and self-help course group) [
Nine studies [
There was much variability in the outcome measures used in the included studies. Pain intensity was assessed using the VAS in five studies [
FMS severity was evaluated using the FIQ in eleven studies [
After critical review of each study included, it was concluded that all the studies included in this exceeded minimum thresholds for methodological and scientific quality.
However, since it is impossible to blind participants to group assignment in exercise intervention protocols, all studies were considered to be at a high risk of bias with respect to blinding of participants and personnel (Table
Risk of bias within studies.
Wigers et al. 1996 | Jones et al. 2002 | Richards and Scott 2002 | Rooks et al. 2007 | Bircan et al. 2008 | Duruturk et al. 2015 | García-Martínez et al. 2012 | Gavi et al. 2014 | Hooten et al. 2012 | Kayo et al. 2012 | Larsson et al. 2015 | Mannerkorpi et al. 2010 | Sañudo et al. 2010 | Sañudo et al. 2011 | Ericson et al. 2016 | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Random sequence generation | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
Allocation concealment | Low risk | Low risk | Low risk | Low risk | Risk unclear | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
Blinding of participants and personnel | High risk | High risk | High risk | High risk | High risk | High risk | High risk | High risk | High risk | High risk | High risk | High risk | High risk | High risk | High risk |
Blinding of outcome assessment | Risk unclear | Low risk | Low risk | Risk unclear | Risk unclear | Low risk | Risk unclear | Low risk | High risk | Risk unclear | Low risk | Low risk | Low risk | Low risk | Low risk |
Incomplete outcome data | Low risk | High risk | Low risk | Low risk | High risk | Low risk | High risk | High risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
Selective reporting | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
Other bias | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
Risk of bias graph: review authors’ judgements about each risk of bias item presented as percentages across all included studies.
The means, SDs, sample sizes, and effect estimates for all studies can be seen in the forest plot (Figures
Forest plot: effect of exercise on pain. SD: standard deviation; IV: inverse variance; CI: confidence interval
Effect of exercise on FMS severity. SD: standard deviation; IV: inverse variance; CI: confidence interval
Effect of exercise on physical component of HRQOL. SD: standard deviation; IV: inverse variance; CI: confidence interval
Effect of exercise on mental component of HRQOL. SD: standard deviation; IV: inverse variance; CI: confidence interval
Effect of exercise on symptoms of depression. SD: standard deviation; IV: inverse variance; CI: confidence interval
Results are reported as SMDs (95% confidence interval). In the case of pain scales, FMS impact, and depression a negative result indicates that the treatment produced an improvement in patients’ condition; but the opposite is true for HRQOL, where a positive effect of treatment is indicated by a positive SMD. There is strong evidence from intention-to-treat and per protocol analysis that exercise reduces pain (−1.11 [95% CI] −1.52, −0.71; overall effect
There was strong evidence on the basis of intention-to-treat and per protocol analysis that
There was moderate evidence on the basis of intention-to-treat analysis that
Heterogeneity (measured as
The remaining data on outcome variables were homogeneous and therefore other sensitive analyses were not necessary.
On visual inspection, the funnel plot of posttreatment outcomes was symmetrical and there was thus no evidence of publication bias. Due to heterogeneity produced by Kayo et al.’s study, data from this study were excluded for this analysis (Figure
Funnel plot of publication bias. SE: error standard; SMD: standardized mean difference; FIQ: fibromyalgia impact questionnaire; HRQOL: health-related quality of life.
The use of various exercise interventions in the studies presented above notwithstanding any physical activity is damaging for people with FMS.
This is the first meta-analysis to assess the most effective exercise for improving some symptoms or conditions in fibromyalgia.
Aerobic exercise for 30 to 60 minutes at an intensity of 50–80% of maximum heart rate 2 or 3 times per week for a period of 4–6 months and muscle strengthening exercises (1 to 3 sets of 8–11 exercises, 8–10 repetitions with a load of 3.1 kg or 45% of 1 repetition maximum (RM)) seem to be most effective in decreasing the pain and severity of FMS. Stretching the major muscle groups and aerobic exercise can improve the physical and mental component of HRQOL, respectively. Combined exercise programs consisting of aerobic exercise, muscle strengthening, and stretching exercises performed for 45–60 minutes 2 or 3 times per week for 3–6 months seem to be the most effective in reducing the symptoms of depression. The findings of this research are consistent with two previous equivalence studies [
The results of other meta-analyses were also considered. In 2010, Häuser et al. [
In another meta-analysis published by Kelley et al. [
This meta-analysis had several limitations, one of which is the sample size of the included studies; most used relatively few participants. In addition, studies included in this meta-analysis were performed predominantly in women due to the fact that fibromyalgia is a syndrome with a significant female predominance [
Unlike pharmacological studies, which are easily blinded, behavioral and physical treatment requiring the active participation of patients is virtually impossible to be blinded.
It is also important to take into account the heterogeneity of the studies, primarily due to the inclusion of the studies of Kayo et al. and Jones et al. [
Another important limitation is that each type of therapeutic exercise was investigated in only a small number of studies. Aerobic exercise is the most commonly studied type of exercise treatment for FMS.
Exercise is beneficial for people with FMS but it is unable to draw any conclusions about what type of exercise is most effective because not enough studies were included in this meta-analysis. There is some evidence to suggest that muscle strengthening and aerobic exercise are most effective in reducing the pain and severity of the disease whilst stretching and aerobic exercise produce the biggest improvements in HRQOL. Combined exercise is the most effective way of reducing symptoms of depression. Although there is still no consensus, it seems that 2 or 3 sessions of mild to moderate intensity physical activity lasting 30–45 minutes each are effective.
It would be interesting to conduct primary research into the type of exercise likely to yield the highest rate of adherence to an exercise treatment regime using a larger sample, because for the effects to be sustained the patients must continue with regular physical activity.
It would also be interesting to investigate whether group and individual physical activity have similar psychological benefits.
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
The authors declare that there are no conflicts of interest.
M. Dolores Sosa-Reina and Susana Nunez-Nagy equally contributed to this study.
This project was carried out with the help of the University of Alcalá (UAH) which awarded contracts for predoctoral research to M. Dolores Sosa-Reina (FPI-UAH). This work was partially supported by grants from the Fondo de Investigación de la Seguridad Social, Instituto de Salud Carlos III (PI14/01935), Spain.