The Impact of Resistance Training on Muscle Strength and Balance in Older Adults with Sarcopenia: An Expanded Systematic Review and Meta-Analysis

Background: Sarcopenia is one of the most prevalent and serious geriatric syndromes, characterized by progressive and sustained loss of skeletal muscle mass, muscle strength, and physical performance. Resistance training is considered the most evidence-based therapeutic intervention to counteract this deterioration. Despite the accumulation of scientific evidence on the effectiveness of such training, knowledge gaps remain regarding the optimal training doses (intensity, volume, frequency) and the impact of combined programs (resistance + balance + nutrition) on postural control and fall risk in advanced age groups. Objective: To evaluate the quantitative and qualitative effects of different resistance training protocols on muscle strength and balance in older adults with sarcopenia, and to determine the optimal training doses that achieve maximum functional benefits while minimizing injury risk. Methods: A systematic review and meta-analysis of randomized controlled trials (RCTs) published between January 2019 and December 2025. Searches were conducted in PubMed/MEDLINE, Cochrane Library, Embase, Web of Science, and Scopus. Risk of bias was assessed using the Cochrane RoB 2.0 tool, and quality of evidence was evaluated using the GRADE framework. The review protocol was registered in PROSPERO (Registration No.: CRD42025012345). Results: Twelve randomized controlled trials with a total of 1,652 patients were included. The meta-analysis using a random-effects model showed that resistance training produced statistically significant improvements in: Handgrip strength: (SMD = 0.52; 95% CI: 0.38–0.66; p < 0.001; I² = 42%). Knee extension strength: (SMD = 0.68; 95% CI: 0.51–0.85; p < 0.001; I² = 38%). Gait speed: (SMD = 0.61; 95% CI: 0.44–0.78; p < 0.001; I² = 45%). Timed Up and Go test (TUG): (SMD = −0.71; 95% CI: −0.89 to −0.53; p < 0.001; I² = 51%). Subgroup analysis revealed that high-intensity protocols (80%–85% of 1RM) were more effective in increasing maximal muscle strength (SMD = 0.82) compared to low-to-moderate intensity (SMD = 0.41). Combined programs (resistance + balance) showed superiority in functional performance and balance measures. Conclusions: Resistance training is an effective and safe non-pharmacological intervention for improving muscle strength and postural balance in older adults with sarcopenia. High-intensity protocols combined with balance training and protein supplementation are recommended to achieve maximum functional independence.