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Adverse events of exercise therapy in randomised controlled trials: a systematic review and meta-analysis
  1. Andre Niemeijer1,
  2. Hans Lund2,
  3. Signe Nilssen Stafne3,4,
  4. Thomas Ipsen1,
  5. Cathrine Luhaäär Goldschmidt1,
  6. Claus Thomas Jørgensen1,
  7. Carsten B Juhl1,5
  1. 1 Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
  2. 2 Centre for Evidence-Based Practice, Hogskulen pa Vestlandet, Bergen, Norway
  3. 3 Department of Public Health and Nursing, University of Science and Technology (NTNU), Trondheim, Norway
  4. 4 Clinic of Clinical Services, Trondheim University Hospital (St Olavs Hospital), Trondheim, Norway
  5. 5 Department of Physiotherapy and Occupational Therapy, University of Copenhagen, Herlev and Gentofte Hospital, Copenhagen, Denmark
  1. Correspondence to Professor Hans Lund, Centre for Evidence-Based Practice, Hogskulen pa Vestlandet, Bergen 5020, Norway; hans.lund{at}


Objective To evaluate the relative risk (RR) of serious and non-serious adverse events in patients treated with exercise therapy compared with those in a non-exercising control group.

Design Systematic review and meta-analysis.

Data sources Primary studies were identified based on The Cochrane Database of Systematic Reviews investigating the effect of exercise therapy.

Eligibility criteria At least two of the authors independently evaluated all identified reviews and primary studies. Randomised controlled trials were included if they compared any exercise therapy intervention with a non-exercising control. Two authors independently extracted data. The RR of serious and non-serious adverse events was estimated separately.

Results 180 Cochrane reviews were included and from these, 773 primary studies were identified. Of these, 378 studies (n=38 368 participants) reported serious adverse events and 375 studies (n=38 517 participants) reported non-serious adverse events. We found no increase in risk of serious adverse events (RR=0.96 (95%CI 0.90 to 1.02, I2: 0.0%) due to exercise therapy. There was, however, an increase in non-serious adverse events (RR=1.19 (95%CI 1.09 to 1.30, I2: 0.0%). The number needed to treat for an additional harmful outcome for non-serious adverse events was 6 [95%CI 4 to 11).

Conclusion Participating in an exercise intervention increased the relative risk of non-serious adverse events, but not of serious adverse events. Exercise therapy may therefore be recommended as a relatively safe intervention.

PROSPERO registration number


  • evidence based review
  • exercise
  • exercise rehabilitation
  • exercises
  • rehabilitation

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  • Contributors HL, AN, TI, SNS and CLG conceived the research. HL, CBJ, AN, TI, SNS and CLG participated in pilot testing the screening and data abstraction forms, helped conceptualise the analysis and interpreted the data. HL and CBJ wrote the first draft of the manuscript. HL coordinated the study. HL, CBJ, AN, TI, SNS, CTJ and CLG screened citations and full texts, resolved discrepancies. HL and CBJ verified data accuracy and analysis and prepared the tables and figures. HL, CBJ, AN, TI, SNS, CTJ and CLG reviewed the manuscript. CBJ analysed and HL, AN, TI, SNS, CTJ and CLG helped interpret the data and reviewed the manuscript. AN and CTJ carried out risk of bias assessment. HL, CBJ, AN, TI, SNS and CLG provided clinical content expertise, verified categorisation of patient population health condition for analysis. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.