How Exercise Helps Reduce the Risk of Osteoarthritis

Summarized by Robert W. Griffith, MD
November 21, 2005

Introduction

Physical activity is generally regarded as being a good treatment for osteoarthritis (OA), provided it isn't limited by pain in the affected joints. Two physicians in Sweden have now done a study in middle-aged people at risk of developing OA and found a possible mechanism for the beneficial effects of exercise in preventing deterioration of the knee joint. Moderate exercise seems to build up knee cartilage, while loss of cartilage is one of the main structural changes in OA. The study findings are reported in the medical journal Arthritis & Rheumatism, and are summarized here.

What was done

Forty-five volunteers who had undergone a partial removal of their medial meniscus (a knee cartilage) 3-5 years earlier were randomized to undergo a one-hour program of supervised exercise, 3 times a week for 4 months, or to a control group that received no treatment.

At baseline they had a specialized magnetic resonance imaging (MRI) of their knee, called delayed gadolinium-enhanced MRI of cartilage, or dGEMRIC. This permitted the amount of glycosaminoglycan (GAG) in their cartilage to be estimated. GAG is related to the elastic properties of cartilage.

What was found

There were 16 women among the 45 volunteers. Their average age was 46, and their body mass index (BMI) was 26.6 kg/m², indicating slight overweight.

Thirty of the 45 patients had dGEMRIC exams done at baseline and after the 4-month study period. The 16 subjects in the exercise group had a significantly improved level of GAG in their cartilage, while the 14 subjects in the no-treatment group showed deterioration in their GAG level.

Moreover, the amount of improved GAG content was associated with the amount of exercise reported by the participants - the more the exercise, the greater the increase in GAG. And the subjects who worked out also reported improvements in pain, quality-of-life, and physical performance scores.

What this means

The fact that the patients had all had a previous menisectomy meant they were considered to be at high risk of developing OA. This was bolstered by their being slightly overweight.

The change seen in GAG content with exercise indicates that "human cartilage responds to physiological loading in a way similar to that exhibited by muscle and bone", according to one of the study's authors. And this suggests that the improvements in symptoms reported with exercise are likely due to improvements in the quality of the cartilage, at least in the short-term.

The bottom line - a structured exercise program can help ward off osteoarthritis in those who are at risk of developing it. And, of course, it's good for general health as well, whether you're at risk of OA or not.

Source

• Positive effects of moderate exercise on glycosaminoglycan content in knee cartilage; a four-month, randomized, controlled trial in patients at risk of osteoarthritis. REW. Roos , DL. Dahlberg , Arthritis & Rheumatism, 2005, vol. 52, pp. 3507--3514

Related Links
Osteoarthritis
Weight Loss and Exercise can help treat Sore Knees
Regular Exercise Reduces the Pain of Osteoarthritis
Arthritis Foundation: Exercise and Arthritis

Please take a moment to give us your comments. For questions about Health matters you may check our "Questions & Answers" Portal and Service.