Resistance training may improve knee extensor strength in frail older adults, but evidence certainty is lowResistance training may improve muscle strength in frail older adults

Background and ObjectiveFrailty is associated with muscle weakness, impaired physical function, and increased risk of disability and loss of independence, making preservation of muscle function an important public health goal for healthy aging. Resistance training may help address these deficits, but its effects in frail or pre-frail older adults remain uncertain. This systematic review and meta-analysis evaluated its effects on muscle strength, physical function, and frailty score.MethodsSeven electronic information sources were searched from inception to August 2026, with no language restrictions. Randomized controlled trials were included if they enrolled adults aged ≥60 years who were clearly diagnosed as frail or pre-frail using validated tools or comprehensive assessments. The intervention was limited to structured resistance training without combination with other exercise modalities. Random-effects models were used for meta-analysis, and the certainty of evidence was assessed using the GRADE approach.ResultsNine randomized controlled trials comprising 27 study arms and 566 participants were included. Low-certainty evidence suggested that resistance training may improve knee extensor strength (SMD = 1.30, 95% CI: 0.48 to 2.13). Very-low-certainty evidence showed possible improvements in handgrip strength (MD = 4.15 kg, 95% CI: 0.81 to 7.48) and gait speed (MD = 0.13 m/s, 95% CI 0.00 to 0.26), whereas the effects on Timed Up and Go (TUG), Short Physical Performance Battery (SPPB) and frailty score remained uncertain. For handgrip strength, gait speed, TUG, and SPPB, clinical importance remained uncertain because the 95% CI encompassed the corresponding reference thresholds for clinical importance. Between-study heterogeneity was substantial to considerable.ConclusionResistance training may improve knee extensor strength and may also benefit handgrip strength and gait speed in frail or pre-frail older adults, although the certainty of evidence is low to very low; effects on TUG, SPPB, and frailty score remain uncertain. Because muscle weakness and functional decline contribute to disability and loss of independence in later life, these findings may inform resistance-training strategies aimed at supporting muscle health and healthy aging. Further high-quality trials with standardized training prescriptions and longer-term follow-up are needed.Systematic review registrationhttps://www.crd.york.ac.uk/PROSPERO/view/CRD420261391816, identifier: CRD420261391816.