Bone Abstracts

Background: Exercise is widely recommended to preserve bone health in postmenopausal women, but the osteogenic dose of physical activity remains poorly defined because intervention intensity is inconsistently described across studies. The osteogenic index (OI) and its components amplitude (A), cycles (C), and frequency (F), may provide a more mechanistically relevant framework for quantifying osteogenic dose using continuous measures. This review aimed to evaluate the effects of physical activity interventions quantified by OI and its components on femoral neck bone outcomes in postmenopausal women.

Methods: Six electronic databases (PubMed, Cochrane, Embase, Scopus, SPORTDiscus, and Web of Science) were searched from inception to 1 January 2026. Randomised controlled trials involving postmenopausal women were eligible if interventions lasted at least 6 months and provided sufficient detail to quantify exercise loading. Outcomes included femoral neck bone mineral density (BMD) or bone mineral content (BMC). Random-effects meta-analysis was conducted using standardised mean differences (SMDs), with subgroup analyses by intervention type and exploratory meta-regression with leave one out (LOO) analyses examining OI and its components (A,C,F).

Results: Fifteen studies were included, comprising 459 participants in exercise groups and 410 in control groups. Overall, exercise interventions significantly improved femoral neck outcomes compared with controls (SMD 0.32, 95% CI 0.11 to 0.53, P 0.001), with moderate heterogeneity (I² 53%). Weight-bearing exercise showed a borderline significant effect (SMD 0.23, 95% CI 0.00 to 0.46, P 0.05), whereas resistance training showed a significant moderate effect (SMD 0.56, 95% CI 0.19 to 0.94, P 0.001); however, the between-subgroup difference was not significant (P 0.13). Following a meta-regression and LOO analyses of weight-bearing interventions, the continuous measure of amplitude became significant after the exclusion of one study. OI was not significantly associated with effect size in weight-bearing interventions.

Conclusion: Exercise interventions benefit femoral neck bone health in postmenopausal women. With limited sample size, exploratory meta-regressions demonstrate that while a robust dose-response relationship is not supported between OI and intervention effectiveness, the continuous measure of amplitude is positively associated with outcomes at the femoral neck. Future trials of exercise intervention effectiveness should be designed using bone-specific characteristics of loading.