The health hazards of sitting for long periods can be offset by two minutes of walking every hour, says a study.

Low-intensity activities such as standing may not be enough, according to the findings published in the Clinical Journal of the American Society of Nephrology (CJASN).

It has been shown that sitting for extended periods of time each day leads to increased risk of heart disease, diabetes and other health conditions.

Scientists at the University of Utah School of Medicine used observational data from the National Health and Nutrition Examination Survey (NHANES) to examine whether longer durations of low-intensity activities (e.g. standing), and light intensity activities (e.g. casual walking, light gardening, cleaning) extends the life span of people who are sedentary for more than half of their waking hours.

Neither decreasing sitting by two minutes each hour nor two minutes of low-intensity activities benefited participants. However, light intensity activities for two minutes each hour were associated with a 33% lower risk of dying.

"It was fascinating to see the results because the current national focus is on moderate or vigorous activity. To see that light activity had an association with lower mortality is intriguing," says lead author Srinivasan Beddhu, MD, professor of internal medicine.

The recommended amount of exercise in the US is 2.5 hours of moderate activity each week.

Take short walks

However, strolling and other light activities use energy, too. Even short walks add up to a lot when repeated many times over the course of a week, the study found.

For16 awake hours each day, two minutes of strolling each hour expends 400 kcal each week, compared to the 600 kcal it takes to accomplish the recommended weekly goal of moderate exercise.

"Based on these results we would recommend adding two minutes of walking each hour in combination with normal activities, which should include 2.5 hours of moderate exercise each week," says Beddhu.

Moderate exercise strengthens the heart, muscles, and bones, and confers health benefits that low and light intensity activities can't.

The 3,243 NHANES participants wore accelerometers that measured the intensities of their activities. Participants were followed for three years after the data was collected; there were 137 deaths during this period.

"Exercise is great, but the reality is that the practical amount of vigorous exercise that can be achieved is limited. Our study suggests that even small changes can have a big impact," says senior author Tom Greene, director of the Study Design and Biostatistics Center at the Center for Clinical and Translational Science.

Sitting for many hours per day has been associated with increased coronary artery calcification, that can increase the risk of a heart attack, said a recent study while adding that it was not good enough to exercise for 30 minutes a day and be sedentary for 23 and a half hours.

Studies have demonstrated that decreasing sedentary time by two to three hours in a 12-hour day by standing or moving for one to three minutes every half hour should reduce health risks.