Effectiveness of High‐Intensity Versus Low‐To‐Moderate‐Intensity Resistance Training in Improving Muscle Strength and Bone Mineral Density in Older Adults: A Systematic Review and Meta‐Analysis of Randomized Controlled Trials

BACKGROUND: Sarcopenia and osteoporosis are common age-related conditions that lead to frailty, functional decline, and increased fracture risk. Resistance training (RT) improves muscle strength and bone mineral density (BMD), but the optimal training intensity remains unclear. OBJECTIVE: This systematic review and meta-analysis synthesized evidence from randomized controlled trials evaluating high-intensity (≥ 70% one-repetition maximum) versus low-to-moderate-intensity (< 70% one-repetition maximum) RT in older adults (age ≥ 50 years). METHODS: The review included 18 studies (1283 participants). The primary outcomes were lower limb muscle strength (leg press and leg extension), lumbar spine BMD, and femoral neck BMD. The secondary outcomes were fall incidence and adverse events. Standardized mean differences (SMDs) and risk ratios (RRs) were pooled using a random-effects model. RESULTS: High-intensity RT significantly outperformed low-to-moderate-intensity RT in improving leg press (SMD: 0.95; 95% confidence interval [CI]: 0.48-1.43) and leg extension (SMD: 0.63; 95% CI: 0.09-1.17). No significant between-regimen difference was observed in lumbar spine BMD (SMD: 0.28; 95% CI: -0.02 to 0.58), femoral neck BMD (SMD: 0.13; 95% CI: -0.08 to 0.33), fall incidence (RR: 2.68; 95% CI: 0.65-11.11), or adverse events (RR: 2.42; 95% CI: 0.66-8.88). CONCLUSION: High-intensity RT outperforms low-to-moderate-intensity RT in improving lower limb muscle strength in older adults. The modalities appear similarly effective in maintaining BMD. No significant between-regimen differences were observed in fall incidence or adverse events, suggesting similar safety profiles. Further randomized controlled trials with well-defined populations and standardized RT protocols are required to validate these findings. TRIAL REGISTRATION: International Prospective Register of Systematic Reviews Database: CRD420251076841.