Walking 6,000 steps per day may protect people at risk of knee OA

A new study shows that walking reduces risk of functional limitation associated with knee osteoarthritis (OA). In fact, the study funded in part by grants from the National Institutes of Health (NIH) and published in the American College of Rheumatology (ACR) journal, Arthritis Care & Research, suggests that walking 6,000 or more steps per day may protect those with or at risk of knee of OA from developing mobility issues, such as difficulty getting up from a chair and climbing stairs.

Nearly 27 million Americans age 25 and older are diagnosed with OA according to a prevalence study by Lawrence et al. (Arthritis Rheum, 2008). Previous research reports that knee OA is the leading cause of functional limitation among older adults, making walking and climbing stairs difficult. Moreover, data from the National Health and Nutrition Examination Survey (NHANES III) state that 80% of OA patients have some limitation in movement, with 11% of adults with knee OA needing assistance with personal care assistance.

While walking is a common daily physical activity for older adults, medical evidence reports that two-thirds of U.S. adults with arthritis walk less than 90 minutes each week. "Our study examines if more walking equates with better functioning, and if so, how much daily walking is needed to minimize risk of developing problems with mobility in people with knee OA," said Daniel White, PT, ScD, from Sargent College at Boston University in Massachusetts.

For the present study, researchers measured daily steps taken by 1788 people with or at risk for knee OA, who were part of the Multicenter Osteoarthritis Study. Walking was measured with a monitor over seven days and functional limitation evaluated two years later, defined as a slow walking speed and a Western Ontario and McMaster Universities Arthritis Index (WOMAC) physical function score greater than 28 out of 68.

Walking an additional 1,000 steps each was associated with between a 16% to 18% reduction in incident functional limitation two years later. Walking less than 6,000 steps daily was the best threshold for identifying those who developed functional limitation. Dr. White concludes, "Walking is an inexpensive activity and despite the common popular goal of walking 10,000 steps per day, our study finds only 6,000 steps are necessary to realize benefits. We encourage those with or at risk of knee OA to walk at least 3,000 or more steps each day, and ultimately progress to 6,000 steps daily to minimize the risk of developing difficulty with mobility."