Middle-aged men and women who engage in high levels of physical activity might damage their knees and increase their risk for osteoarthritis, according to a study presented at the annual meeting of the Radiological Society of North America.
"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 Dr. Christoph Stehling, research fellow in the Department of Radiology and Biomedical Imaging at the University of California, San Francisco.
Osteoarthritis is a degenerative joint disease that causes pain, swelling, and stiffness. It is the most common form of arthritis and affects an estimated 27 million American adults, according to the Centers for Disease Control and Prevention.
The study involved 236 asymptomatic participants who had not reported previous knee pain, including 136 women and 100 men, ages 45 to 55, within a healthy weight range. The participants were separated into low-, middle-, and high-activity groups based on their responses to the Physical Activity Scale for the Elderly questionnaire. The scale is a standard test that scores an older individual's physical activity level, based on the type of activity and the time spent doing it. Several factors contribute to the final score, but a person whose activity level is classified as high typically might engage in several hours of walking, sports or other types of exercise a week, as well as yard work and other household chores.
Subsequent MRI analysis indicated a relationship between physical activity levels and frequency and severity of knee damage. Specific knee abnormalities identified included meniscal lesions, cartilage lesions, bone marrow edema, and ligament lesions.
"The prevalence of the knee abnormalities increased with the level of physical activity," Stehling said. "In addition, cartilage defects diagnosed in active people were more severe."
The findings also indicated that some activities carry a greater risk of knee damage over time.
"This study and previous studies by our group suggest that high-impact, weight-bearing physical activity, such as running and jumping, may be worse for cartilage health," Stehling said. "Conversely, low-impact activities, such as swimming and cycling, may protect diseased cartilage and prevent healthy cartilage from developing disease."
