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.