Nov. 29, 2010 (Chicago) -- Light exercises such as walking and bowling and avoidance of knee-bending activities such as climbing and squatting may protect against osteoarthritis of the knee in at-risk people, researchers report.
On the flip side, high-impact sports such as running and skiing are associated with knee cartilage damage in people who are overweight, have had knee injuries or knee surgery, have a family history of osteoarthritis, or have other risk factors, according to a study presented here at the annual meeting of the Radiological Society of North America (RSNA).
Osteoarthritis is a degenerative joint disease that causes pain, swelling, and stiffness. According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases, it's the most common form of arthritis, affecting an estimated 27 million Americans over the age of 25.
The new study involved 132 people at risk for knee osteoarthritis who were enrolled in the National Institutes of Health Osteoarthritis Initiative, as well as 33 people of similar ages and weight who were not at risk. Participants included 99 women and 66 men aged 45 to 55.
The researchers, led by Keegan Hovis, RN, of the University of California at San Francisco, separated participants into three exercise levels:
Sedentary: watching TV, reading, or other sitting activities more than two hours a day, two or more days a week.
Light exercisers: walking, playing darts, Frisbee or other light activities two or more hours a day, three or more days a week.
Moderate to strenuous exercisers: running, cycling, or other moderate to strenuous sports more than an hour a day, three or more days a week.
Knee-bending activities such as climbing, kneeling, and lifting heavy objects were also analyzed.
Virtues of Light Exercise
Among people with osteoarthritis risk factors, MRI scans showed that light exercisers had the least amount of cartilage damage.
"It can be postulated that light exercise is protective against osteoarthritis" in these individuals, Hovis tells WebMD.
The scans also showed that women with osteoarthritis risk factors who fell into the moderate-to-strenuous exercise category had substantially more collagen degeneration in their knees than any other group.