A new study published in the Clinical Journal of the American Society of Nephrology cautions that engaging in low-intensity activities such as standing may not be enough to offset the health hazards of sitting for long periods of time. It does however say that adding two minutes of walking each hour to your routine will help.
Realizing that most people wont replace sitting with additional exercise, scientists at the Utah School of Medicine took a look at the health benefits of a more achievable goal. Using observational data from the National Health and Nutrition Examination Survey they studied whether longer durations of low-intensity activities such as standing and light intensity activities - cleaning, casual walking and light gardening - extended the life span of people who were sedentary for more than half of the hours they were awake.
The study examined 3,243 participants who wore accelerometers that objectively measured the intensities of their activities. Participants were followed for three years after the data was collected. There were 137 deaths during this period.
- There is no benefit to decreasing sitting by two minutes each hour, and adding a corresponding two minutes more of low intensity activities. However, a trade-off of sitting for light intensity activities for two minutes each hour was associated with a 33 percent lower risk of dying.
- While it's obvious that it takes energy to exercise, 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.
- Assuming 16 awake hours each day, two minutes of strolling each hour expends 400 kcal each week. That number approaches the 600 kcal it takes to accomplish the recommended weekly goal of moderate exercise. It is also substantially larger than the 50 kcal needed to complete low intensity activities for two minutes each awake hour over the course of one week.
- Large, randomized, interventional trials will be needed to definitively answer whether exchanging sitting for light activities leads to better health.
"It was fascinating to see the results because the current national focus is on moderate or vigorous activity, said lead author Srinivasan Beddhu, M.D., professor of internal medicine. To see that light activity had an association with lower mortality is intriguing. 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. Moderate exercise strengthens the heart, muscles, and bones, and confers health benefits that low and light-intensity activities can't.
"Exercise is great, but the reality is that the practical amount of vigorous exercise that can be achieved is limited, added senior author Tom Greene, Ph.D., director of the Study Design and Biostatistics Center at the Center for Clinical and Translational Science. Our study suggests that even small changes can have a big impact."