When Less Can Do More

In that a number of studies suggest that the more time people spend in moderate or vigorous activities, the less likely they are to develop disability, Dorothy Dunlop, from Northwestern University Feinberg School of Medicine (Illinois, USA), and colleagues investigated whether spending more time in light activities can help prevent disability as well.  The researchers identified a group of 1,680 adults, ages 45 to 79 years, from the Osteoarthritis Initiative study who were free of disability but were at elevated risk for developing it because they had knee osteoarthritis or other risk factors for knee osteoarthritis, such as obesity.  To track the amount and intensity of physical activity these at-risk people engaged in every day, the team had them wear an accelerometer during waking hours for about a week.  Two years after collecting the results from the accelerometer, participants were surveyed and asked about the development of disabilities. As expected, more time spent in moderate or vigorous activity was associated with lower reports of disabilities, and researchers found that greater time spent in light intensity activities also was related to fewer disabilities, even after accounting for time spent in moderate activities.  Those who spent more than four hours per day doing light physical activity had more than a 30% reduction in the risk for developing disability, as compared to those spending only three hours a day in light activity.  Submitting that: “These prospective data showed an association between greater daily time spent in light intensity physical activities and reduced risk of onset and progression of disability in adults with osteoarthritis of the knee or risk factors for knee osteoarthritis.” The study authors encourage for:  “An increase in daily physical activity time may reduce the risk of disability, even if the intensity of that additional activity is not increased.”