Public release date: 28-Sep-2007
Exercise for cardiovascular health keeps knee cartilage healthy, too, suggests long-term, community-based study
The world’s most common joint disease, osteoarthritis (OA) is a major cause of disability among adults over the age of 50. Whether physical activity is beneficial or detrimental to weight-bearing joints, knees in particular, has been open to debate. Some studies implicate physical activity in provoking knee OA, while others suggest that physical activity may actually protect the knee joint from the disease. Confounding the matter is the fact that knee injury is a known risk factor for knee OA. Then, there’s the unclear role of osteophytes in knee OA progression, compounded by the limitations of radiographs for monitoring small yet significant changes in joint structure
Among the notable findings, both baseline and current vigorous physical activity— exercise that gets the heart pumping and the body sweating—were associated with an increase in tibial cartilage volume, free from cartilage defects. What’s more, tibial cartilage volume increased with frequency and duration of vigorous activity. Recent weight-bearing exercise was also linked to increased tibial cartilage volume and reduced cartilage defects. Finally, moderate physical activity, including regular walking, was associated with a 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,” notes the study’s leading author, Dr. Flavia M. Cicuttini. “Bone marrow lesions have been associated with pain and radiograph-defined progression of osteoarthritis, type II collagen degradation, and loss of cartilage volume.”
Demonstrating a protective effect of past and current vigorous physical activity on knee cartilage in healthy adults, this study strongly supports the benefits of exercise for older individuals at risk for OA. Though both the intensity and duration of physical activity had a significant positive impact on cartilage, the ideal amount of physical activity for joint health remains unclear. “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,” Dr. Cicuttini observes.
Article: “Effect of Physical Activity on Articular Knee Joint Structures in Community-Based Adults,” Tina L. Racunica, Andrew J. Teichtahl, Yuanyuan Wang, Anita E. Wluka, Dallas R. English, Graham G. Giles, Richard O’Sullivan, and Flavia M. Cicuttini, Arthritis Care & Research, October 2007; (DOI: 10.1002/art.22990).