Heavy weights offer no extra relief for arthritic knees

Strength training is a mainstay of managing knee osteoarthritis, but a practical question divides opinion: does training harder buy more relief, or does it simply load an already sensitive joint for no extra return? Many people with arthritic knees are wary of heavy lifting, while others assume that more intensity must mean more benefit. This review set out to compare high-intensity strength training directly against low-intensity strength training or routine care in adults with knee osteoarthritis, across pain, function, quality of life and safety.

The authors searched PubMed, Embase, Cochrane Library and Web of Science for studies published up to 10 March 2021. Ten studies covering 892 subjects with knee osteoarthritis were included. Outcomes spanned the standard toolkit for this condition: pain and stiffness scores from the WOMAC index, multiple domains of the Knee Injury and Osteoarthritis Outcome Score including symptoms, daily living, sport and quality of life, plus the Timed Up and Go test, gait velocity, walking time, knee muscle strength and adverse event rates.

On nearly every outcome there was no significant difference between the high-intensity group and the low-intensity or routine care group. That covered pain scores, stiffness, physical function, daily living, sport and recreation, Timed Up and Go, gait velocity, walking time, knee extensor strength, quality of life and the incidence of adverse events. The single exception was the peak torque of the knee flexors measured at 120 degrees per second, where the high-intensity group improved significantly more, with a pooled difference of 7.520. The authors concluded that high-intensity training may deliver similar benefits with comparable safety.

The finding complicates the intuitive assumption that more training intensity yields proportionally more benefit, at least in this population and for these outcomes. It sits comfortably alongside the wider evidence that strength training helps knee osteoarthritis, while suggesting the intensity dial matters less than often supposed. Because the comparison group mixed lighter training with routine care, the analysis cannot separate those two, and it says nothing about how either approach compares to doing no exercise over the long term. Longer trials with cleaner comparisons would sharpen the answer.

For anyone training around achy knees, this is a reason to think the benefit of strength work does not depend on lifting heavy: lighter programmes matched high-intensity ones on pain, function and quality of life, with similar safety. The one advantage for heavier training was a specific measure of knee flexor strength, which may matter to some people and not others. The broader message is informational: intensity looks like a preference rather than a requirement in this setting.