Increased Risk of Knee Arthritis Linked to Too Much Exercise

A new study has found that middle-aged men and women who over-exercise may be unknowingly causing damage to their knees, putting themselves at greater risk of developing osteoarthritis (OA).

Researchers at the University of California, San Francisco (UCSF; USA) and the University of Muenster (Germany) analyzed data of 100 men and 136 women aged 45 to 55 taking part in the U.S. National Institutes of Health (NIH) Osteoarthritis Initiative. None of the participants reported experiencing knee pain before enrollment, and their weight was in the healthy range. The researchers then categorized the participants according to their responses to a questionnaire that assessed their physical activity according to the Physical Activity Scale for the Elderly (PASE); according to the results, the participants were then put in one of three groups: low activity (PASE score 27-155), middle activity level (PASE 156-230), and high activity (PASE 231-409). Two of the researchers then analyzed magnetic resonance imaging (MRI) images of the participants to assess severity of any cartilage, meniscal, and ligament damage, or other abnormalities, in the right knee.

The results showed that 47% of the participants had meniscal lesions; 74.6% had cartilage lesions; 40.3% had bone marrow edema; and 17% had ligament lesions. The incidence of abnormalities went up in line with PASE activity level, as did the grade of cartilage lesions. Presence of other knee abnormalities was also significantly linked to presence of cartilage defects. Additionally, the abnormalities were linked solely with activity levels and were not age or gender specific. The study was presented at the 95th scientific assembly and annual meeting of the Radiological Society of North America (RSNA), held November-December 2009 in Chicago (IL, USA).

"Our data suggest that people with higher physical activity levels may be at greater risk for developing knee abnormalities and, thus, at higher risk for developing osteoarthritis,” said lead author and study presenter Christoph Stehling, M.D., of UCSF and the University of Muenster. "High-impact, weight-bearing physical activity, such as running and jumping, may be worse for cartilage health. Conversely, low-impact activities, such as swimming and cycling, may protect diseased cartilage and prevent healthy cartilage from developing disease.”

A middle-aged person who spends several hours a week walking, doing sport and other exercises, plus yard work, heavy gardening and household chores would have a high PASE score.

Related Links:
University of California, San Francisco
University of Muenster