British analysis of previously collected data indicates there’s no link between the amount of an individual’s exercise and their risk for knee arthritis.

The analysis combined the results of six clinical trials conducted at various locations worldwide, resulting in analysis of more than 5,000 people who were followed for between five and 12 years for signs of knee arthritis. Results of the team’s research were published in the journal Arthritis and Rheumatology.

Clinical trials involved researchers tracking participants’ daily activities and estimating the amount of energy expended in physical exertion. Researchers concluded that neither the amount of energy expended during exercise nor the amount of time engaged in physical activity exerted any influence on participants’ knee pain or arthritis symptoms.

“This helps dispel a myth that I’ve been trying to dispel for quite a while,” said Kim Huffman, MD, PhD, a rheumatologist and associate professor at the Duke University Medical Center’s division of rheumatology in Durham, NC. “If you add up the amounts of activity that people do and also the duration of activity, neither of those is associated with knee arthritis,” she said.

Bert Mandelbaum, MD, who specializes in orthopaedics and sports medicine at the Cedars-Sinai Kerlan-Jobe Institute in Santa Monica, CA, agreed with the study’s conclusions. He said the study “further corroborates the fact that levels of exercise in one’s personal life do not increase the risk, the onset or progression of osteoarthritis.”

Huffman believes the mistaken conclusion that exercise increases the risk of knee arthritis results from exercise-related injuries individuals may experience. “Right now the clear risks for knee arthritis are genetics, injuries and female sex,” she said. “People who exercise more may be more likely to injure their knees. That’s where I think the myth comes from.” In fact, she said, exercise can actually help prevent knee arthritis in several ways.

For example, exercise creates an elevated metabolism that helps to control inflammation in the knee joint. Exercise’s associated weight control reduces the mount of load placed on the knees. Exercise helps to strengthen the muscles around the knee joint, stabilizing it and reducing the risk of injury. And, flexing and extending the knee during exercise promotes the diffusion of fluid into the knee joint, bolstering nutrition.

“I don’t think we’re finding that simple overuse or using your joint is a problem,” Huffman said. “It’s more an association with injuries and perhaps in the setting of obesity or high genetic risk.” She recommended selecting an exercise or activity that poses the lowest risk of a knee injury.

“If you want to go snow skiing, I don’t think that’s a huge problem but you’re probably going to be more likely to injure yourself downhill skiing than, say, walking in your neighborhood or training for a marathon,” she said. “It’s not soccer or football or skiing itself. It’s just the risk for injury during those activities.”

Mandelbaum noted that exercise provides benefits that stretch beyond healthy joints. “Physical activity is essential to optimize both physical and mental health and plays a central role in facilitating life’s quality and quantity,” he said. “The list of benefits includes decreased anxiety, better mood, decreased levels of coronary disease, hypertension, diabetes and obesity, and therefore a longer life.”

Neither Huffman nor Mandelbaum was involved in the British study.