RT Journal Article SR Electronic T1 Adverse events of exercise therapy in randomised controlled trials: a systematic review and meta-analysis JF British Journal of Sports Medicine JO Br J Sports Med FD BMJ Publishing Group Ltd and British Association of Sport and Exercise Medicine SP 1073 OP 1080 DO 10.1136/bjsports-2018-100461 VO 54 IS 18 A1 Niemeijer, Andre A1 Lund, Hans A1 Stafne, Signe Nilssen A1 Ipsen, Thomas A1 Goldschmidt, Cathrine Luhaäär A1 Jørgensen, Claus Thomas A1 Juhl, Carsten B YR 2020 UL http://bjsm.bmj.com/content/54/18/1073.abstract AB 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 numberCRD42014014819.