Based on the "wear and tear" nature of OA, the commonly held belief is that exercise will not strengthen joint cartilage and may even aggravate cartilage loss. Working with the Department of Orthopedics at Malmö and Lund University Hospitals and the medical faculty of Lund University, Leif Dahlberg, M.D., Ph.D., and Ewa M. Roos, P.T., Ph.D. recruited 29 men and 16 women, between the ages of 35 and 50, who had undergone meniscus repair within the past 3 to 5 years. Subjects were randomly assigned to either an exercise group or a control group. The exercise group was enrolled in a supervised program of aerobic and weight-bearing moves, for 1 hour, 3 times weekly for 4 months.

At the study's onset and follow-up, subjects from both groups underwent MRI scans to evaluate knee cartilage. The technique used focused specifically on the cartilage's glycosaminoglycan (GAG) content, a key component of cartilage strength and elasticity. Subjects also answered a series of questions about their knee pain and stiffness, as well as their general activity level.

In the exercise group, many subjects reported gains in physical activity and functional performance tests compared with subjects in the control group. Improvements in tests of aerobic capacity and stamina affirmed the self-reported changes. What's more, MRI measures of the GAG content showed a strong correlation with the increased physical training of the subjects who had regularly participated in moderate, supervised exercise.

But the study does have limitations such as its small sample size and narrow focus on meniscectomized knee joints. The conclusion, however: "Exercise may have important implications for disease prevention in patients at risk of developing knee OA."; Source: John Wiley & Sons, Inc.