Less than 10 minutes a day of brisk walking can help prevent disability in people with arthritis pain in their knee, hip, ankle or foot, researchers report.
Just one hour a week of brisk physical activity "is less than 10 minutes a day for people to maintain their independence. It's very doable," said lead study author Dorothy Dunlop. She's a professor of preventive medicine at Northwestern University's Feinberg School of Medicine in Chicago.
"This minimum threshold may motivate inactive older adults to begin their path toward a physically active lifestyle with the wide range of health benefits promoted by physical activity," Dunlop added in a university news release.
She and her team analyzed four years of data from more than 1,500 older adults in Baltimore, Pittsburgh, Columbus, Ohio, and Pawtucket, R.I., who had pain, aching or stiffness in their lower joints from osteoarthritis but were initially free of disability.
The participants' levels of physical activity were monitored using a wearable device.
An hour a week of moderate-to-vigorous physical activity reduced their risk of disability, the study found. Specifically, the activity reduced the risk of walking too slowly to safely cross a street by 85 percent, and their risk of not being able to do daily living activities -- for example, morning routine tasks such as walking across a room, bathing and dressing -- by nearly 45 percent.
By the end of the four years, 24 percent of participants who did not get a weekly hour of brisk physical activity were walking too slowly to safely cross the street, and 23 percent had difficulty performing their morning routines, according to the study.
About 14 million older Americans have symptomatic knee osteoarthritis, the most common type of osteoarthritis. About 2 in 5 people with osteoarthritis -- most of whom have it in their lower joints -- develop disability.
Federal guidelines recommend low-impact physical activity for older adults with arthritis, and recommend that older adults do at least 2.5 hours a week of moderate-intensity activity.
But that amount of activity can be too much for inactive older adults with lower extremity pain, according to Dunlop.
"We hope this new public health finding will motivate an intermediate physical activity goal," she said. "One hour a week is a stepping stone for people who are currently inactive. People can start to work toward that."
The study was published April 1 in the American Journal of Preventive Medicine.
The Arthritis Foundation offers exercise tips.