Acute responses and chronic effects of blood flow restriction training on bone-related outcomes: a systematic review and multilevel meta-analysis

Objective To evaluate the effects of blood flow restriction training (BFRT) on bone-related outcomes by distinguishing outcome domains, comparator structures, and acute versus chronic responses. Methods Randomized controlled trials investigating BFRT and bone-related outcomes were searched across nine databases from inception to September 1, 2026. Risk of bias, methodological quality, and certainty of evidence were evaluated with RoB 2, TESTEX, and GRADE. Three-level meta-analysis modeled clustering of multiple effect sizes within studies. Results Twenty-two reports were included. BFRT was associated with a small positive BMD effect (SMD = 0.20, 95% CI 0.08 to 0.32, p < 0.01) and an exploratory positive pooled estimate across heterogeneous bone-related regulatory biomarkers (SMD = 0.73, 95% CI 0.28 to 1.19, p < 0.01); the prediction interval for the latter included no effect. No clear pooled effects were observed for acute or chronic bone turnover markers. Study-level moderator findings were exploratory. Conclusion BFRT may modestly improve BMD under some conditions, but evidence is insufficient to infer fracture prevention or long-term clinical benefit. Regulatory biomarkers differ in function and timing, and their pooled response does not demonstrate increased bone formation. Benefits relative to conventional high-load training remain uncertain. Larger trials with standardized BFRT protocols and clinically relevant skeletal outcomes are needed. Systematic review registration https://www.crd.york.ac.uk/PROSPERO/ , identifier CRD420251101440.