(SOURCE: Arthritis Care & Research, news release, Sept. 28, 2007)
TUESDAY, Oct. 2 (HealthDay News) -- Exercise that boosts cardiovascular health may also help keep knee cartilage healthy and protect against knee osteoarthritis, Australian researchers say.
Previous studies on the issue have produced conflicting findings, the team said. Some studies concluded that exercise may trigger knee osteoarthritis, while other studies found that exercise may protect the knees from osteoarthritis.
In this new study, researchers analyzed the effect that varying levels of intensity, frequency and duration of exercise had on the knees of 257 healthy adults, ages 50 to 79, with no history of knee osteoarthritis.
Reporting in the October issue of Arthritis Care & Research, the team found an association between physical activity and good knee health. For example, vigorous activity was linked with healthier cartilage and moderate exercise, including regular walking, was associated with lower incidence of bone marrow lesions.
"This is the first study to demonstrate a potentially beneficial effect of walking on the reduction in the risk of bone marrow lesions in the knee," Dr. Flavia M. Cicuttini, leader of the Melbourne Collaborative Cohort Study, said in a prepared statement. "Bone marrow lesions have been associated with pain and radiograph-defined progression of osteoarthritis, type II collagen degradation, and loss of cartilage volume," she added.
Both exercise intensity and duration had a major positive impact on knee cartilage, but it's not clear what amount of exercise is ideal for joint health, the group said.
"Our data suggest that at least 20 minutes once per week of activity sufficient to result in sweating or some shortness of breath might be adequate. This is similar to, if not somewhat less than, the recommendations for cardiovascular health," Cicuttini said.
More information
The American Academy of Family Physicians has more about knee OA. 
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