Strength training on isokinetic machines eases arthritic knees

Knee osteoarthritis is one of the most common degenerative joint diseases, marked by cartilage breakdown, narrowing of the joint space and bony outgrowths. The result is pain, stiffness, weaker muscles around the joint and, in severe cases, real disability. Strengthening the muscles that support the knee is a logical rehabilitation target, and isokinetic training, performed on machines that control the speed of movement while matching resistance to the user's effort, is one structured way to do it. This review asked whether that approach measurably improves strength, pain and function in people with knee osteoarthritis.

The researchers searched eight Chinese and English databases from their inception to September 2024 for randomised controlled trials of isokinetic muscle strengthening training in people meeting diagnostic criteria for knee osteoarthritis, excluding advanced disease. Eligible trials compared isokinetic training, alone or added to another treatment, against control groups receiving no intervention or a different treatment. In total 46 studies with 2,860 patients were analysed. Outcomes included knee flexor and extensor strength measures, pain on a visual analogue scale, several function and disability scores, and knee range of motion, with study quality formally assessed.

Isokinetic training significantly improved knee flexor and extensor strength at testing speeds of both 60°/second and 180°/second, along with total work, power output and range of motion. Pain scores fell by 0.70 on the visual analogue scale, WOMAC disability scores fell by 6.05 and Lequesne index scores by 1.24, while Lysholm knee scores rose by 7.90 and knee flexion range of motion improved by 10.62 degrees. The benefits held up through subgroup and sensitivity analyses. However, the authors judged the overall quality of the evidence to be poor, driven by disagreement between trials and imprecise results.

Exercise is already a mainstay of managing knee osteoarthritis, and this review adds a specific, machine-based strengthening method to the evidence, with consistent effects on strength, pain and function across dozens of trials. What it cannot yet answer is how isokinetic training compares with simpler, cheaper strength work, how long the benefits last, or what the ideal programme looks like. The authors themselves call for large, high-quality trials with longer follow-up before the method can be widely recommended, so the direction of the finding is clearer than its size.

For anyone with achy, arthritic knees, this is another piece of evidence that stronger muscles around the joint go hand in hand with less pain, less stiffness and better function, not more damage. Isokinetic machines are typically found in rehabilitation and sports science settings rather than ordinary gyms, so this is less a product recommendation than a signal about the value of progressive strength work for the joint. Given the poor quality of the underlying trials, treat the specific numbers loosely and the overall direction seriously.