It's never too late: The impact of resistance training on strength and body composition in females across the lifespan - A systematic review and meta-analysis

OBJECTIVES: Resistance training improves muscular strength and body composition, yet women are underrepresented in research, and guidelines are mainly based on men. No meta-analysis has systematically evaluated its effects on strength and body composition in women. This study therefore synthesizes evidence across the female lifespan and examines potential dose-response relationship. METHODS: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and PROSPERO registration (CRD42024600270), four databases were searched for studies in healthy women (≥18 years) reporting strength or body composition changes after resistance training. Standardized mean differences were pooled using random-effects models. Subgroup analyses compared pre- and postmenopausal women, and meta-regressions examined moderators (age, menopausal status, training frequency, duration). Study quality was assessed with the PEDro scale; analyses were conducted in R. RESULTS: A total of 126 studies including 4019 women (66.2% postmenopausal, mean age 50.9 ± 19.2 years) were analyzed. Resistance training significantly improved muscular strength in both premenopausal (standardized mean difference = 1.50 [95% confidence interval: 1.28-1.73]) and postmenopausal women (standardized mean difference = 1.46 [95% confidence interval: 1.26-1.67]), with no subgroup difference (p = 0.520). Functional mass increased (standardized mean difference = 0.27 [95% confidence interval: 0.18-0.35]), and fat mass decreased significantly (standardized mean difference = 0.30 [95% confidence interval: 0.25-0.35]) in both groups, with no significant subgroup differences (all p > 0.440). Meta-regressions showed no associations between outcomes and age, training duration, frequency, or total sessions (all p > 0.05). CONCLUSIONS: Resistance training appears to be associated with improvements in strength and body composition in women across the lifespan. These findings suggest that general training guidelines could be applicable to women, with individualization remaining important over strict sex- or age-based distinctions.