The Effect of Impact Exercise (Alone or Multicomponent Intervention) on Health-Related Outcomes in Individuals at Risk of Fractures: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Background Exercise is commonly recommended to prevent and manage osteoporosis. High magnitude strains at rapid rate and short bouts should theoretically elicit an osteogenic response; however, the effects of different levels of impact exercises on several outcomes in people at risk of fracture are still unknown. Objective To report the effect of impact exercise on falls, fractures, adverse events, mortality, bone mineral density (BMD), physical functioning, and health-related quality of life (QoL). Methods We included randomized controlled trials testing the effect of impact exercise compared with a non-exercise control on outcomes in adults ≥ 50 years with low BMD or fragility fractures. Two reviewers selected studies and extracted data. Where possible, we pooled outcomes using mean difference (MD) with a fixed-effects model and 95% confidence interval (CI). We reported risk of bias using Cochrane and certainty of evidence using GRADE. Results We included 29 trials; 19 studies evaluated impact exercise alone, and the remaining trials combined impact with resistance or balance training. Impact exercise alone or combined with resistance training improved Timed Up-and-Go values (MD - 0.95 s, 95% CI - 1.09 to - 0.81, low certainty evidence) and lumbar spine (MD 0.04 g/cm2, 95% CI 0.02-0.06, low certainty evidence) and femoral neck BMD (MD 0.04 g/cm2, 95% CI 0.02-0.07, low certainty evidence). Impact exercise did not improve health-related QoL assessed with QUALEFFO-41 (MD 0.06, 95% CI - 2.18 to 2.30, moderate certainty evidence). The effects of impact exercise on falls, fractures, and mortality are uncertain due to insufficient data. Many trials had a high risk of bias for two or more items. Conclusions There is low certainty evidence that impact exercise may improve physical function and BMD in people at risk of fracture. The effect of impact exercises on falls, fractures, and mortality remains unclear. Our findings should be interpreted with caution due to risk of bias and small sample sizes. Trial registration Registered in Prospero (CRD42018115579) on January 30, 2019.