美国国家公共电台 NPR--Sitting all day can be deadly. 5-minute walks can offset harms（在线收听）

Sitting all day can be deadly. 5-minute walks can offset harms

Transcript

If you sit at your computer all day and then lounge on the sofa for more screen time in the evening, your health can take a hit. A body of evidence links sedentary lifestyles to an increased risk of diabetes, dementia and death from heart disease.

And here's a wake-up call: One study found, irrespective of whether a person exercised, if they sat for more than 12-13 hours a day, they were more than twice as likely to die early, compared to people who sat the least.

A new study finds you can cut that risk with strikingly small amounts of activity.

Researcher Keith Diaz of Columbia University Medical Center and his colleagues set out to find out what's the least amount of physical activity a person must do to offset the health risks of sitting. They recruited volunteers to come to their lab and emulate a typical work day.

"They'd come in and sit for eight hours," Diaz explains. The volunteers were hooked up to continuous glucose monitors to measure blood sugar levels, and their blood pressure was measured, too. Then, the participants took walking breaks of varying lengths and frequency.

"We found that a five minute walk every half-hour was able to offset a lot of the harms of sitting," Diaz says.

The participants walked on a treadmill at a leisurely pace – about 1.9 miles per hour. "We were really struck by just how powerful the effects were," Diaz says. People who moved five minutes every half-hour, saw blood sugar spikes after a meal reduced by almost 60%.

"This is surprising to me," says Robert Sallis, a family medicine doctor at Kaiser Permanente, and the past president of the American College of Sports Medicine. It's well known that exercise can help control blood sugar, but he says what's new here is how beneficial frequent, short bouts of movement can be.

"I have never seen that kind of a drop in blood sugar, other than with medication," Sallis says. He says he's impressed by the findings, which are published in an American College of Sports Medicine journal, Medicine & Science in Sports & Exercise.

More than one out of every three adults in the U.S. has prediabetes, and nearly half of adults have high blood pressure, according to the Centers for Disease Control and Prevention. Both conditions increase the risk of heart disease which is the top cause of death in the U.S. So, Sallis says many people can benefit from small, frequent movement breaks.

Each week, adults are advised to get 150 minutes of moderate-intensity physical activity. The CDC says you can break this up into smaller chunks, 30 minutes a day, five times a week for example or even shorter breaks that are more frequent. "I think it's easier to find small amounts of time to get some exercise," Sallis says.

The pace of walking in the study was likely too leisurely to count as 'moderate-intensity' for most people, but Loretta DiPietro, a professor at the Milken Institute School of Public Health, says there are simple ways to increase the intensity, including walking faster. "Add some stairs in," she says. "Swing your arms," which will help engage more muscles.

Another tip: turn on some music, since the beat can prompt you to step up the pace. You may not lose weight with short breaks, but "this is a wonderful way to improve your metabolic profile," DiPietro says, which is so key to good health.

DiPietro was not involved in the new study, but her prior research has also shown that strolls after meals help improve blood sugar control.

She explains the mechanism by which exercise leads to this benefit is well understood: When we exercise, our muscles require glucose – sugar – as the fuel source. DiPietro says when we contract our muscles, our bodies use GLUT4 transporter proteins which rise to the surface of the muscle cell and escort glucose molecules into the cell. So, physical activity helps to clear glucose out of the bloodstream into the muscle where it can be stored and utilized. And this helps lower blood sugar.

At a time when employers are looking for ways to retain workers, DiPietro says encouraging movement during the work day has clear benefits. "The human body was not designed to sit for eight hours at a time," DiPietro says. "What employers can do is provide options for people," she says, such as encouraging walking meetings and promoting more flexibility, which has become more common since the pandemic.

Employers should be aware that there's another likely benefit to short, frequent breaks: "People were in a better mood because they took those breaks," says Kathleen Janz, professor emeritus at the University of Iowa who focuses on health promotion. She reviewed the results of the new study for NPR and noted that participants in the study felt less fatigued.

It's a reminder that moving our bodies during the work day isn't a waste of time, Janz says. In fact it could make us better workers and make us healthier at the same time. "It can be a win-win," says Janz.