26- Walking, Recreational Exercise Do Not Increase Risk for Knee OA in Older Adults

January 31, 2007 — Walking and other 

recreational exercise do not

increase the risk for developing osteoarthritis (OA) in older adults without OA, according to the results of the Framingham Offspring Study reported in the January issue of Arthritis Care & Research.

"Regular exercise is recommended for middle-aged and older persons," write David T. Felson, MD, of the Boston University School of Medicine in Massachusetts, and colleagues. "The effect of regular exercise on the development of osteoarthritis (OA) in older persons, especially those who are overweight, is unclear."

This longitudinal study followed up 1279 community-dwelling adults who were older (mean age at baseline 53.2 years) and many of whom were overweight. Using a questionnaire about physical activity, subjects were asked about recreational activities, including walking or jogging for exercise, and working up a sweat, and they were asked to compare their activity levels with those of others. At baseline, subjects were also asked about knee pain and had weight-bearing anteroposterior (AP) and lateral knee radiographs.

Approximately 9 years later, subjects were reexamined for OA, and radiographs were evaluated for OA features in both tibiofemoral and patellofemoral compartments and scored for tibiofemoral joint space narrowing. Knees with OA at baseline were excluded for all analyses.

The main knee-specific endpoints were incident radiographic OA, symptomatic OA, and tibiofemoral joint space loss. After adjustment for age, sex, body mass index (BMI), knee injury history, and correlation between knees, the investigators evaluated the association of each recreational activity with OA development.

Recreational walking, jogging, frequency of working up a sweat, or high activity levels relative to peers were not associated with decreased or increased risk for OA or with joint space loss. Participants with BMI above the median (27.7 kg/m2 for men and 25.7 kg/m2 for women; mean BMI > 30 kg/m2 for both) had no increases in risk for OA with different types of activity.
Study limitations include lack of MRI imaging at baseline evaluation and insufficient number of joggers or runners to evaluate the effect of running on OA.

"Among middle-aged and elderly persons without knee OA, many of whom were overweight, recreational exercise neither protects against nor increases risk of knee OA," the authors write. "Although dynamic loading may have a trophic effect on cartilage, there is no measurable protective effect of recommended weight-bearing exercise on OA. Physical activity can be done safely without concerns that persons will develop knee OA as a consequence."

The National Heart, Lung, and Blood Institute of the National Institutes of Health's Framingham Heart Study and the Boston University School of Medicine supported this study.
In an accompanying editorial, Marian A. Minor, MD, of the University of Missouri in Columbia, called this "a useful and valid study that supports recommending regular moderate physical activity without undue fear that such activity may increase the risk for knee OA."

"Future research, whether designed to evaluate the effectiveness of interventions or to identify risk factors for development or progression, should characterize subjects in terms of variables relevant to knee OA," Dr. Minor writes. "We must identify and agree upon meaningful characterization of research subjects and move beyond general statements of risk and efficacy in the aggregate.

In addition to improving the usefulness of knee OA research, our ultimate aim must be to produce evidence that assists clinical decision-making and individualized recommendations regarding safety and effectiveness of interventions, including physical activity."

Posted by Mostafa gala & Mohamed rizk