Researchers from Northwestern's Feinberg School of Medicine recently conducted a study, published in the American Journal of Preventive Medicine, to explore the impact of physical activity on individuals with osteoarthritis, a type of arthritis that occurs with aging.
They examined adults ages 49 to 83 from the Osteoarthritis Initiative, a large assessment on osteoarthritis of the knee. The participants experienced pain in their hip, knee, ankle or foot and were at increased risk of disability due to their lower-extremity symptoms, such as aching or stiffness. Scientists followed the subjects from 2008 to 2014.
At the beginning of the trial, the patients were not disabled, which means they had the ability to walk at a speed of at 2 mph and reported no limitation on daily activities like getting dressed or walking across a room.
The scientists determined their activity levels using accelerometers, which measure speed, and interviewed participants about their health every other year for four years.
After analyzing the results, they found those who vigorously exercised at least 56 minutes per week decreased their risk of mobility impairment compared to those who exercised less.
"Identifying an evidence-based physical activity goal which supports these basic abilities may motivate inactive older adults to begin their path towards health benefits from a physically active lifestyle," lead author Dorothy Dunlop told CNN. "If future work shows one hour a week of moderate activity is beneficially related to other health outcomes, this threshold could provide an intermediate physical activity goal."
The authors noted this is the first systemic study to discover the minimum time needed to prevent disability. However, they did note some limitations.
They acknowledged they observed a specific group of patients with only lower extremity joint conditions as opposed to general joint conditions. They also said the accelerometers were not able to record activities in water and may have underestimated cycling activities.
The team now hopes to continue its studies to encourage an active lifestyle among all.