The researchers write that the low proportion of people meeting the exercise guidelines is mirrored by similarly low levels among people in the general population – according to the big National Health and Nutrition Examination Survey (NHANES), only 9.5 percent of men and 7.5 percent of women between the ages of 20 and 69 met the criteria.

“This suggests that non-disease factors, such as lifestyle preferences, scheduling, environmental and policy influences likely play important roles in shaping the overall deficiency of sustained bouts of moderate-to-vigorous intensity walking not only among people with or at high risk of knee OA but also for the overall general population,” the researchers write.

Others experts agree. People with and without knee pain have other reasons why they didn't exercise enough, such as lack of time or safe places to walk, says Leigh F. Callahan, PhD, a professor of medicine at the Thurston Arthritis Research Center, University of North Carolina at Chapel Hill. Callahan was not involved in the study.

Knee OA is the most common type of arthritis; more than 1 in 10 adults in the United States older than 60 have it. Knee OA is the No. 1 cause of disability in older adults, and it increases the risk of all causes of death and becomes more common with age. There are no cures for OA. Treatments focus on reducing pain and increasing movement with medications and other means, including physical activity.

“Large studies have shown that people with painful knee OA who walked regularly eventually had less pain,” White says. “Your pain may increase right after you begin walking or exercising, but in the long run you should see improvement.”

Jennifer Hootman, an epidemiologist with the Centers for Disease Control and Prevention’s Arthritis Program, says once you're comfortable walking for 10 minutes at a time, you should try to increase how long and often you walk to feel better physically and emotionally.

White and Hootman encourage people with knee OA to consider a walking program, such as the Arthritis Foundation’s Walk with Ease program. It is designed to help people with arthritis become more active, and can be done in a group setting or on your own.

People with knee OA can be encouraged by the study's findings, which state that most people with arthritis can meet HHS guidelines. “Knowing that getting more exercise will reduce pain in the future may encourage people to be more willing to deal with some pain to gain the long-term benefits of exercise for managing their arthritis,” Hootman says.

“People with knee OA and pain should think about factors that prevent them from being physically active and how to get past them,” Callahan says.