Exercises are considered an indispensable part of Knee osteoarthritis (OA) management, and International guidelines recommend exercises. Exercise programs, including muscle strengthening exercises of sufficient intensity, are known to be an effective approach for improving muscle strength and endurance in OA patients.

Lately, a systematic review and meta-regression analysis of randomized trials were conducted to investigate whether exercise treatment regimen designed for patients with knee OA following the American College of Sports Medicine (ACSM) definition of muscle strength training varies from other types of exercise. The study also investigated the relationships between changes in muscle strength, pain, and disability.

Randomized controlled trials comparing exercise treatment with no treatment in knee OA and also reporting changes in muscle strength and pain or disability measured as standardized mean differences with 95% CI, were identified during a systematic search of 5 electronic databases. Interventions were classified as ACSM interventions or not-ACSM interventions. The interventions were distinguished using stratified random effects meta-analysis models. Relationships between knee extensor strength gain and changes in pain/disability were evaluated using meta-regression analyses.

The analysis included a total of 45 eligible trials with 4699 participants and 56 comparisons (22 ACSM interventions). A statistically significant difference supporting the ACSM interventions concerning knee extensor strength was found [SMD difference: 0.448 (95% CI: 0.091–0.805)]. There were no variations about effects on pain and disability. The meta-regression analysis showed that improvements in knee extensor strength of 30–40% would be required for a possible concomitant beneficial effect on pain and disability.

The overall results of the study indicate that exercise therapy following the ACSM criteria for strength training provide better outcomes in knee extensor strength but not in pain or disability.