Tailoring Resistance Exercise for Knee Osteoarthritis: An Intervention Systematic Review With Dose-Response...

OBJECTIVES: We aimed (1) to estimate the dose-response relationships between isotonic lower extremity resistance exercise volume and outcomes of pain, function, and strength in people with knee osteoarthritis (OA) and (2) to compare different intensities and delivery methods of isotonic resistance exercise for patients with knee OA. DESIGN: Systematic review with dose-response meta-analysis of randomized controlled trials (RCTs). LITERATURE SEARCH: MEDLINE (Medical Literature Analysis and Retrieval System Online)/PubMed, CENTRAL (Cochrane Central Register of Controlled Trials), Web of Science, CINAHL (Cumulative Index of Nursing and Allied Health), and EMBASE (Excerpta Medica Database) were searched from inception to January 2, 2025. STUDY SELECTION CRITERIA: RCTs evaluating isolated isotonic resistance training without other exercise interventions in people with knee OA were included. DATA SYNTHESIS: Pain, function, and muscle strength were analyzed. Risk of bias was assessed using the Cochrane Risk of Bias 2.0 tool; certainty of evidence, using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach; and dose-response relationships, using restricted cubic spline models. RESULTS: Twenty RCTs were included (n = 791). Low- to very low-certainty evidence indicated that isotonic resistance training may reduce pain, improve function, and increase muscle strength in people with knee OA. Very light- to moderate-intensity isotonic exercise produced the greatest reductions in pain; moderate-intensity, the greatest improvements in function; and moderate- to vigorous-intensity, similar gains in muscle strength. Benefits were seen with home- and center-based programs; the effects were more pronounced with center-based programs. For the dose-response analyses, there was a nonlinear relationship, with greater estimated pain reductions at 6000 repetitions (mean difference [MD], -3.52; 95% confidence interval [CI]: -4.08, -2.96), peak functional improvements at 2600 repetitions of moderate intensity (MD, -16.66; 95% CI: -18.80, -14.51), and maximal strength gains at 1600 repetitions (standardized MD, 0.12; 95% CI: 0.01, 0.22). CONCLUSION: Isotonic resistance training may improve pain, function, and muscle strength in people with knee OA. Moderate-intensity exercise and specific training volumes were associated with the greatest estimated benefits, although the certainty of evidence was low to very low. J Orthop Sports Phys Ther 2026;56(9):585-595. Epub 6 Aug 2026. doi:10.2519/jospt.2026.13477.