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Minimum 45 minutes of weekly activity led to sustained function in adults with OA
Research is needed on whether patients with chronic conditions would benefit from moderate activity.
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Recently published results showed adults with lower limb joint symptoms were 80% more likely to experience improved function or sustain high function who met a minimum physical activity threshold of 45 total moderate-vigorous minutes per week compared to those doing less.
“The take-home message is 45 minutes a week of moderate activity, like brisk walking, is a minimum threshold to improve or sustain high function. This minimum target is valuable as an initial step towards meeting the current federal guidelines of 150 minutes a week,” Dorothy D. Dunlop, PhD, professor of medicine and preventative medicine at Northwestern University in Chicago, told Orthopedics Today.
Improved function, gait speed
Dunlop and her colleagues clinically assessed 1,629 adults with symptomatic lower limb joint pain, aching or stiffness who were enrolled in the Osteoarthritis Initiative accelerometer monitoring sub-study for improved or high physical function status for whom baseline and 2-year follow-up data were available. They measured physical function by gait speed and the SF-12 physical component score.
Researchers investigated optimal thresholds that predicted improved or high function using classification trees. Thresholds were evaluated for weekly minutes spent in total moderate-vigorous activity, moderate-vigorous activity in bouts that lasted 10 minutes or more, sedentary activity, light intensity activity and non-sedentary.
Results showed a minimum threshold of 45 minutes per week of total physical activity of moderate-vigorous intensity was the strongest predictor of improvement from low function or sustained high function for 2 years. The minimum 45-minute activity threshold best predicted improved or high function in both gait speed and SF-12 physical function score and represented a less stringent standard compared with the current federal physical activity threshold of 150 minutes of activity per week.
“Even a little activity is better than none, but the more activity you do, the greater the health benefits,” Dunlop said. “While we are pleased to see some health benefits with 45 minutes a week, that is only a starting point because the more time spent being active, the greater the benefits. The federal guidelines remain important for cardiovascular benefit.”
Current guidelines
Although there is strong evidence supporting the current federal guideline of 150 minutes a week of moderate activity, individuals with lower joint symptoms, such as knee or hip osteoarthritis, may have trouble meeting those guidelines, according to Dunlop.
Therefore, a lower threshold of 45 minutes of activity per week may “be an incentive for [individuals] to start to become active and move them towards better health benefits,” she said.
“What we think we have is an initial step that might feel more feasible to people who have painful knees or painful hips for whom federal guidelines seem daunting. But, 45 minutes a week may not only seem possible, but they could also hope to see benefits in their function,” Dunlop said.
The study participants were part of a general population with hip and knee symptoms. Dunlop noted future research could investigate whether being active at least 45 minutes a week would be beneficial for adults with chronic conditions. She also noted it would be important to find out if this minimum threshold would have other health benefits. – by Casey Tingle
- Reference:
- Dunlop DD, et al. Arthritis Care Res. 2016;doi:10.1002/acr.23181.
- For more information:
- Dorothy D. Dunlop, PhD, can be reached at Institute for Healthcare Studies, Feinberg School of Medicine, Northwestern University, 630 N. Saint Claire St., 20th Fl., Chicago, IL 60611; email: ddunlop@northwestern.edu.
Disclosure: Dunlop reports she received funding from the NIH.