Moderate exercise neither increases nor decreases risk of knee osteoarthritis, a new study finds. In knee osteoarthritis, the cartilage at the joint wears down, causing bones to rub against each other leading to pain, swelling, and stiffness. Some past studies had suggested that exercise can reduce the risk of developing this form of arthritis by making knee-joint cartilage stronger, whereas other studies suggested that when older people exercise they can injure their knee joints and actually increase osteoarthritis risk, especially if they are overweight. But a recent study led by Dr. David Felson at the Boston University School of Medicine suggests that moderate exercise has no effect on the risk of developing knee osteoarthritis. For the study, Felson and colleagues took knee X-rays of 1,279 people, ranging in age from their 20s to their 80s and also asked them to report knee pain, stiffness, and level of physical activity. After nine years, the participants were reassessed. Researchers found that moderate exercise had no bearing on the risk of developing knee osteoarthritis.

BOTTOM LINE: Older people – even those who are overweight – will not damage their knees by getting moderate exercise. “This is a good thing because exercise is important for older people,” Felson said.

CAUTIONS: The study is the first to show that exercise does not affect knee osteoarthritis risk. More research is needed to confirm these findings.

WHAT’S NEXT: Felson hopes someone will investigate how more vigorous exercise affects knee osteoarthritis risk.

WHERE TO FIND IT: Arthritis Care & Research, February.
SENA DESAI GOPAL