High levels of physical activity 'may lead to arthritis'

Published on 30 Nov 2009

People who regularly take certain types of high impact exercise may be more likely to develop arthritis, new research suggests.

Exercise is generally regarded to be beneficial for maintaining joint health and people with osteoarthritis often find that their symptoms can be helped by maintaining an active lifestyle.

However, a study by researchers at the University of California, San Francisco (UCSF) suggests that certain types of exercise can actually harm the joints if performed at high intensity on a regular basis.

The team studied 236 people - including 136 women and 100 men - who had no history of knee pain and were enrolled in the National Institutes of Health Osteoarthritis Initiative Study.

Participants were aged between 45 and 55 and had a healthy body weight.

The researchers divided the participants into three groups depending on whether they performed low, moderate or high levels of physical activity.

High levels of activity were deemed to involve several hours of walking, sports or other types of exercise per week, as well as regular gardening or household chores.

MRI scans revealed that people who did the most physical activity tended to have greater degrees of knee damage, including meniscal, cartilage and ligament lesions and bone marrow oedema.

Presenting the team's findings at the annual meeting of the Radiological Society of North America, researcher Dr Christoph Stehling revealed: "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.

"The prevalence of the knee abnormalities increased with the level of physical activity. In addition, cartilage defects diagnosed in active people were more severe."

The researcher observed that while high-impact, weight-bearing activities such as running and jumping may have a negative effect on cartilage health, "low-impact activities such as swimming and cycling may protect diseased cartilage and prevent healthy cartilage from developing disease".

A spokeswoman for the Arthritis Research Campaign said the results of the study were not surprising, adding that the gains of exercise far outweighed any potential risks.

"We have known for years that certain high impact sports and jobs are associated with an increased risk of osteoarthritis, particularly of the knee, but for the vast majority of people exercise is good, not only for the cartilage but for total body health," she said.

"Most people can exercise without any problems but if you have had a joint injury or torn cartilage or ligaments you should be cautious about exercise, and swimming and cycling may provide a better option for you.

"It's a matter of balance and sensible moderation, as the risk of developing osteoarthritis as a result of too much exercise is outweighed by the risk of being overweight and sedentary.

"We always advise people who already have arthritis to keep as fit and mobile as possible within their limitations and for them, non-weight-bearing exercises such as swimming and cycling are the best."