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Sedentary lifestyles can be unhealthy, physical activity can lower risk

A quarter of Americans sit for more than eight hours a day even though this lifestyle can be deadly. Here's how to offset the health risks of sitting.
/ Source: TODAY

Don’t get too comfortable in that seat: Parking in a chair all day can be deadly, as plenty of "sitting is the new smoking" research has found.

But replacing 30 minutes of sitting time with physical activity — even light exercise accumulated in short bouts lasting just a few minutes — can cut your risk of early death by up to a third, according to a study published Monday in the American Journal of Epidemiology.

Any movement of any intensity is beneficial to offset sitting risks — though the more vigorous the activity, the better, the researchers said.

The common routine of sitting at work all day, then plopping down on the couch all evening horrify experts like Keith Diaz, the study’s lead author and an assistant professor of behavioral medicine at the Columbia University Medical Center.

“It’s terrible. And this whole binge-watching Netflix is particularly problematic,” Diaz told TODAY.

“Sitting for two or three hours straight is one of the most hazardous things you can do for your body. What’s particularly problematic, we think, is that we eat a large meal — we eat dinner — and then we watch TV for the rest of the night. That combination is really lethal.”

Why is extended sitting so unhealthy?

Your body was designed to move, not stay still. Muscles play a role in regulating blood sugar levels, but when you sit, they become inactivated and stop taking sugar out of the blood stream, Diaz said. “The metabolic engines go to sleep,” Dr. James Levine, an obesity researcher, told NBC News. That can cause a host of consequences, including higher blood pressure, and increase a person’s risk of diabetes and heart disease, Diaz noted.

Indeed, people who sat the most were more likely to die from 14 different diseases, a survey from the American Cancer Society found last year. The causes of death included cancer, coronary heart disease, stroke, diabetes, kidney disease, suicide, COPD (such as emphysema), pneumonitis due to inhaling something, liver disease, peptic ulcer and other digestive disease, Parkinson’s disease, Alzheimer’s, nervous disorders and musculoskeletal disorders.

But we’re not changing our habits: A quarter of Americans sit for more than eight hours a day; 40 percent get no exercise during the week; and 10 percent say they both sit longer than eight hours a day and are physically inactive, according to a study published in JAMA last year.

Sit less, move more

For the new paper, Diaz and his colleagues analyzed data from almost 8,000 people who took part in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study from 2009 to 2013. All wore a gadget that tracked their physical activity and sedentary times for a week. The researchers then looked at their death rate through 2017 and, after crunching all the available data, estimated how substituting sedentary time with physical activity would impact the risk of early death.

They found:

  • replacing 30 minutes of sitting time with light intensity physical activity, such as casual walking, would reduce the risk of early death by 17 percent.
  • trading 30 minutes of sitting time with moderate-to-vigorous physical activity, such as walking very briskly, running or biking, was associated with cutting the risk of early death by more than a third, or 35 percent.

It doesn’t have to be 30 continuous minutes of movement; rather, you can accumulate them during the day.

“It was thought activity wasn’t beneficial unless you did it in these bouts of 10 minutes or longer. And we found that wasn’t true: even a one-minute movement break had some health benefit,” Diaz said.

The effects of replacing sedentary time with activity are theoretical in the study, a statistical model, but Diaz was confident they would hold up in real life.

Sitting is probably less risky when you’re taking frequent movement breaks, every 30 minutes or so, his previous study found, but if you’re sitting for many hours a day — even in those short bouts — it’s still hazardous, Diaz said.

His basic prescription for better health: Sit less, move more, and move frequently.

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