Just under one hour of moderate to vigorous exercise each week is all that is needed to help patients with hip, knee and ankle joint symptoms remain disability-free, according to a US study.

While most health agencies recommend 150 minutes of moderate-intensity exercise per week to prevent disability, the Northwestern University-led researchers have found just 56 minutes is the threshold for preventing mobility disability (gait speed less than 1m/second) over four years.

And in order to prevent limitations with daily living activities, only 55 minutes of moderate to vigorous exercise was enough, according to data on more than 1500 people aged over 49 with hip, knee, ankle or foot pain, aching or stiffness.

This exercise threshold remained consistent regardless of sex, BMI, age and radiographic presence of osteoarthritis, the researchers reportws in the American Journal of Preventative Medicine.