Knee osteoarthritis (OA) is one of the most common musculoskeletal disorders in the world. Resistance training has many beneficial effects on musculoskeletal function, cardiovascular disease, insulin action, bone health, energy metabolism, psychological health and functional status. Since quadriceps weakness, obesity and abnormal mechanical joint forces are related to the development and progression of knee OA, resistance training could play a vital role in easing the discomfort of this disease. A new study reviewing trials on resistance interventions in patients with knee OA found that it improved muscle strength, pain and physical functioning in many patients. The study is published in the October issue of Arthritis Care & Research (http://www3.interscience.wiley.com/journal/77005015/home).
Researchers conducted a systematic database search for randomized controlled trials involving adults with knee OA and some form of resistance training, which included resistance machines, free weights, isometric exercise or other devices such as elastic bands.
The literature review found that the development of knee OA depends on a variety of factors, with quadriceps weakness being one of the main factors that was modified by resistance training. More than half of the studies found an improvement in self-reported pain and 79 percent found an improvement in self-reported disability/mobility following resistance training, with progressive resistance training associated with an overall increase in physical activity levels. The authors state that future clinical trials on the benefit of long term exercise interventions in knee OA should also examine long-term changes in the knee cartilage and surrounding bone, which can be assessed with MRI. They note that up until now, research on knee OA and exercise has rarely centered on objective measures such as medication use, nursing home admissions, health care use, progression to joint replacement, and cost-effectiveness.
Overall, the majority of the studies included in the review found that knee OA symptoms, physical function and strength were improved with resistance training. Because strength changes have been shown by several authors to be related to symptoms and physical function at various training intensities, large trials comparing different intensities of progressive resistance training would be needed to answer this question fully, according to the authors. They conclude that further studies are needed to evaluate how strength training affects health-related quality of life, psychological outcomes, disease progression and overall health care use.
My Comments: I am often asked about the benefits of physical therapy on knee arthritis. I often advise patients that it is worth trying but may not help everyone. It is unlikely to make the pain worse and will not cause the arthritis to progress faster. Physical therapy may be worth a try in certain cases of knee osteoarthritis.