Just 11 minutes of exercise a day can help reverse the effects
Sitting is, indeed, quite bad for you. But moving is very good for you, even in small doses.
If you have a desk job, there’s a chance that the pandemic has made your life even more sedentary than usual: Your commute to work might now involve rolling over in bed and opening your laptop. (Ask me how I know.) But a new study suggests that even relatively tiny amounts of exercise during the day can help offset some of the negative health impacts of sitting for hours.
“A lot of the early research and news headlines from three or four years ago used to say things like ‘sitting is the new smoking’ even if you exercise, and there was this notion that exercise doesn’t matter if you sit all day,” says Keith Diaz, an assistant professor of behavioral medicine at Columbia University and one of the coauthors of the study. “What I think this study shows is that they both matter. The harm that comes from sedentary behavior can be altered by how much [moderate-to-vigorous intensity physical activity] that you do, and also vice versa: how much benefit you get from exercise depends on how much sitting time you do.”
The study, a meta-analysis of nine other studies tracking nearly 45,000 people, found that those who were most sedentary risked dying prematurely. But even when people sat as much as 8.5 hours a day, getting just 11 minutes of moderate exercise significantly cut that risk. Thirty to 40 minutes of exercise was even more helpful.
The exercise—which needs to be the equivalent of brisk walking or biking to count as moderate-to-vigorous—likely doesn’t have to happen at once. In a previous study, researchers saw that movement throughout the day also helps. “It doesn’t matter if you accrue it in 30 minutes or one-minute bouts over 30 occasions,” Diaz says. “The guidelines historically used to recommend that it had to be 10 minutes or more time, and we found that that’s just not the case. Any movement, no matter what duration, is beneficial, as long as you accrue enough of it.”
Some previous studies had suggested that it might take as much as 75 minutes of exercise a day to offset the harms of being sedentary the rest of the time. But older studies relied on self-reported data, which is notoriously inaccurate. People both can’t remember the precise amount of time that they were sitting, and tend to want to make themselves sound less lazy than they actually are. But newer studies use objective data from activity monitors.
Diaz emphasizes that 11 minutes of exercise won’t eliminate the risk of long hours of sitting. But if some amount of sedentary time is unavoidable, any movement helps. “I think an important message here is that there are many different ways to get at lowering your health risk in terms of movement,” he says. “You could be a person who says, ‘I’m a bus driver, I’m a cab driver, and I can’t move throughout my day and break up my sitting time—literally part of my job is to sit. But when I get out of my job, I can go to the gym. And if I get exercise for 30 minutes, that will actually help negate a lot of my harmful behaviors at work.” Others might not have time to go to the gym after work, but might have jobs that let them take short breaks to get up and move. “If I’m just periodically moving through my day, that’s going to lower my risk,” he says. “So we have a number of different ways to get there.”
The study didn’t take into account the amount of time people spend standing each day, since activity monitors can’t tell if someone is sitting or standing. But despite past hype for standing desks, the science isn’t yet clear on whether standing helps. Some studies suggest that standing for two or three hours can increase blood pressure. “We don’t know if standing is necessarily any better,” Diaz says. “When people ask me what they should do to mitigate the harms if they have a sitting job, we know that movement is good. We’ve known that for decades. And that’s really what I endorse.”