Adverse events of exercise therapy in randomised controlled trials: a systematic review and meta-analysis

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.

Systematic review and meta-analysis.

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

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.

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).

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.