Tailoring Resistance Exercise for Knee Osteoarthritis: An Intervention Systematic Review With Dose-Response Meta-Analysis of the Effects of Intensity and Volume

OBJECTIVE: 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). We aimed to compare different intensities and delivery methods of isotonic resistance exercise for patients with knee OA.

DESIGN: Systematic review and dose-response meta-analysis of randomized controlled trials (RCTs).

LITERATURE SEARCH: MEDLINE/PubMed, CENTRAL, Web of Science, CINAHL, and EMBASE were searched from inception to 2 January 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 Grading of Recommendations, Assessment, Development and Evaluations (GRADE), 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 produced the greatest improvements in function, and moderate to vigorous intensity produced similar gains in muscle strength. Benefits were seen with home-based and center-based programs; the effects were more pronounced with center-based programs. For the dose-response analyses, there was a non-linear relationship, with greater estimated pain reduction at 6,000 repetitions (mean difference [MD]: −3.52, 95% confidence interval [CI]: −4.08 to −2.96), peak functional improvements at 2,600 repetitions at moderate intensity (MD: −16.66, 95% CI: −18.80 to −14.51), and maximal strength gains at 1,600 repetitions (SMD: 0.12, 95% CI: 0.01 to 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.