Adverse Events of Exercise Therapy in Randomised Controlled Trials: a Systematic Review and Meta-analysis

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, I: 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, I: 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 numberCRD42014014819.