Optimal Resistance Exercise Strategies for Improving Bone Mineral Density in Middle-Aged and Older Adults: A Network Meta-Analysis Based on Exercise Intensity and Frequency.

Abstract

This study used a network meta-analysis to evaluate the effects of different resistance training intensities and frequencies on bone mineral density (BMD) in middle-aged and older adults, aiming to identify the optimal exercise strategy for each skeletal site. PubMed, Embase, Cochrane, Web of Science, Google Scholar, and Scopus databases were searched for randomized controlled trials (RCTs) meeting the inclusion criteria. The Cochrane RoB 2 tool was used for literature quality assessment, and Stata 17.0 was used for network meta-analysis. The standardized mean difference (SMD) and 95% confidence interval (CI) were used for effect size pooling. Interventions were ranked using the surface under the cumulative ranking (SUCRA). Thirty-four RCTs (n = 1746 participants) were included. For BMD at the lumbar spine (LS), femoral neck (FN), total hip (TH), trochanter (Troch), and Ward's triangle (WT), moderate-intensity resistance training three times per week (3MI) ranked highest in SUCRA probability, with SUCRA values of 80.3%, 75.2%, 68.2%, 86.0%, and 80.5%, respectively. For total body (TB) BMD, high-intensity resistance exercise twice weekly (2HI) ranked highest in SUCRA probability, with a SUCRA value of 88.9%. Compared with the control group, 3MI significantly increased BMD at the FN (SMD = 0.26, 95% CI 0.06, 0.46) and Troch (SMD = 0.34, 95% CI 0.10, 0.58). Compared with the control group, both 2HI (SMD = 0.49, 95% CI 0.07, 0.91) and 3MI (SMD = 0.30, 95% CI 0.01, 0.59) significantly increased TB BMD. Subgroup analyses showed that exercise frequency, intensity, duration, session length, study population sex, bone health status, and age significantly influenced BMD at different sites.  Based on SUCRA probability rankings, 3MI had the highest-ranking probability for improving BMD at the LS, FN, TH, Troch, and WT, while 2HI had the highest-ranking probability for improving TB BMD. However, no statistically significant differences were observed between interventions at the LS, TH, or WT, and these ranking results should be interpreted with caution.