Researchers have found that recreational exercise has no effect on the risk of developing knee osteoarthritis (OA). The results of their study, which monitored 1,279 older adults over a 9-year study period, suggested that older adults-even people who are overweight--can participate in recreational exercise without worrying that they might develop knee OA as a result. The research was partly supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS).
David T. Felson, M.D., and his colleagues at Boston University School of Medicine and Brigham and Women's Hospital studied 1,279 adults whose parents or in-laws participated in the original Framingham Heart Study. The average age of participants at the start of the study was 53.2 years. After baseline evaluation between 1993 and 1994, the researchers followed the participants for nine years on average, to see if recreational activity levels influenced development of knee OA.
When enrolling the subjects, the researchers asked them about knee pain symptoms and activities levels (including walking or jogging for exercise and working up a sweat). The researchers also weighed the participants and examined X-rays of their knee joints to check for narrowing of joint spaces, which is a sign of OA. Approximately seven years later, researchers quizzed participants about the extent to which they exercised regularly. Two years later, they called the subjects back, weighed them again, and re-examined them for OA using knee radiographs and asking questions about knee pain and injury.
Using data from baseline and follow-up examinations, the researchers assessed whether exercise had any influence on knee OA. Analysis showed that neither recreational walking, jogging, frequently working up a sweat, nor high activity levels in comparison to peers changed the risks of developing knee OA. Comparing radiographs taken at baseline and at study completion, the authors reported that physical activity did not increase or decrease chances of narrowing of knee joint space, a typical sign of knee OA.
Being overweight or obese is a risk factor for developing knee OA. Therefore, the researchers looked into the relationship between exercise and knee OA among participants who were overweight or obese. The results for overweight or obese participants were similar to those for all participants: none of the activities that were monitored changed risks of developing knee OA or having narrowed knee joint space. That means that for obese or overweight persons, exercise does not increase the risk of developing knee arthritis, in contrast to results from previous studies.
OA is the most common type of arthritis, and is seen especially among older people. An estimated 12.1 percent of the U.S. population (nearly 21 million Americans) age 25 and older have OA. It is also more likely to occur in people who are overweight and in those with jobs that stress particular joints. Osteoarthritis mostly affects cartilage, the hard but slippery tissue that covers the ends of bones where they meet to form a joint. Osteoarthritis most often occurs in the hands, spine, knees and hips. People with osteoarthritis usually have joint pain and some movement limitations. Fortunately, most people with osteoarthritis live active, productive lives despite these limitations. They do so by using treatment strategies such as exercise, weight control, rest and relief from stress on joints, pain relief techniques, medications, surgery, and complementary and alternative therapies.
Other support for this research came from the National Institute on Aging and the National Heart, Lung, and Blood Institute.
The mission of the NIAMS, a part of the Department of Health and Human Services' National Institutes of Health, is to support research into the causes, treatment and prevention of arthritis and musculoskeletal and skin diseases; the training of basic and clinical scientists to carry out this research; and the dissemination of information on research progress in these diseases. For more information about NIAMS, call the information clearinghouse at (301) 495-4484 or (877) 22-NIAMS (free call) or visit the NIAMS Web site at http://www.niams.nih.gov.
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Felson DT, et al. Effect of recreational physical activities on the development of knee osteoarthritis in older adults of different weights: the Framingham Study. Arthritis & Rheumatism 2007;57:6-12.