That's the upshot of a new study by Dutch researchers that says people with osteoarthritis of the knee must come up with a workable exercise plan if they want to stave off potentially severe muscle deterioration.
"It's sort of a downward spiral. As people feel more pain, they exercise less, which in the long term leads to muscle weakness and even more disability," says Martin P.M. Steultjens, a scientist with the Netherlands Institute of Health Services Research in Utrecht.
Steultjens is the lead author of the study, which is the first to document the logical assumption that the muscle weakness that results from inactivity increases the disability suffered by those with osteoarthritis of the knee.
Results of the study appear in the July issue of Arthritis & Rheumatism.
The study included 107 older men and women who'd been diagnosed with osteoarthritis of the knee for at least one year. Steultjens and his colleagues found that approximately 25 percent of the patients' disability could be traced to a lack of physical activity that had weakened their muscles, causing their joints to become less stable and less able to bear their weight.
The result: They were more disabled than they would have been had they been able to maintain their muscle strength.
"This study shows the association between pain and disability. In the early stages of osteoarthritis, patients have pain and, afraid to have pain again, they become inactive," Steultjens says.
Steultjens and his colleagues tested the patients, three-quarters of whom were women, for pain levels, disability levels and muscle strength. They used the Pain Coping Inventory test to assess the patients' levels of pain. The test uses a series of questions asking patients to describe their activities when they feel pain. Then the researchers assessed the patients' levels of disability by videotaping them doing various activities. Finally, using a machine that tests muscle resistance, they measured the patients' muscle strength.
The results, Steultjens says, show that people should be encouraged to keep up some kind of activity even while suffering from osteoarthritis.
"The association between physical activity and pain should be countered," he says.
Dr. Joel Press, medical director of the Center for Spine, Sports and Occupational Rehabilitation of the Rehabilitation Institute of Chicago, says, "trying to put objective numbers on subjective issues is very tough, but this study gives a framework for better understanding the strength-deficit loss of the muscles with osteoarthritis."
"When you can quantify these things, it gives backup to what you do," he adds.
Press says exercising with osteoarthritis is possible as long as you tailor the program to each patient.
"You have to be a little creative, and look at each person differently to find exercises he or she can tolerate and that don't increase the pain," he says.
For example, he says, if someone has trouble walking, you could try an elliptical trainer, an exercise machine that keeps weight off the joints. Or a stationary bicycle. Or swimming, if someone has access to a pool.
"You find exercises people can tolerate and that keep the muscles stronger without making them worse," he says.
Osteoarthritis afflicts an estimated 21 million Americans, mostly after the age of 45, and women are more commonly affected than men, according to The Arthritis Foundation.
What To Do
A thorough explanation of osteoarthritis and how it is treated can be found at The Arthritis Foundation. Johns Hopkins University also offers some interesting information about diagnosing the disease.