Exercise and the prevention of major osteoporotic fractures in adults: a systematic review and meta-analysis with special emphasis on intensity progression and study duration

SUMMARY: The role of exercise in preventing osteoporotic fractures is vague, and further recommendations for optimized exercise protocols are very rare. In the present work, we provided positive evidence for exercise effects on the number of osteoporotic fractures in adults, albeit without observing any significant relevance of intensity progression or study duration. INTRODUCTION: Osteoporotic fractures are a major challenge confronting our aging society. Exercise might be an efficient agent for reducing osteoporotic fractures in older adults, but the most promising exercise protocol for that purpose has yet to be identified. The present meta-analysis thus aimed to identify important predictors of the exercise effect on osteoporotic fractures in adults. METHODS: We conducted a systematic search of six literature databases according to the PRISMA guideline that included controlled exercise studies and reported the number of low-trauma major osteoporotic fractures separately for exercise (EG) and control (CG) groups. Primary study outcome was incidence ratio (IR) for major osteoporotic fractures. Sub-analyses were conducted for progression of intensity (yes vs. no) during the trial and the study duration (≤ 12 months vs. > 12 months). RESULTS: In summary, 11 studies with a pooled number of 9715 participant-years in the EG and 9592 in the CG were included. The mixed-effects conditional Poisson regression revealed positive exercise effects on major osteoporotic fractures (RR: 0.75, 95% CI: 0.54–0.94, p = .006). Although studies with intensity progression were more favorable, our subgroup analysis did not determine significant differences for diverging intensity progression (p = .133) or study duration (p = .883). Heterogeneity among the trials of the subgroups (I(2) ≤ 0–7.1%) was negligible. CONCLUSION: The present systematic review and meta-analysis provided significant evidence for the favorable effect of exercise on major osteoporotic fractures. However, diverging study and exercise characteristics along with the close interaction of exercise parameters prevented the derivation of reliable recommendations for exercise protocols for fracture reductions. PROSPERO ID: CRD42021250467.