There is a golden rule for writers who hope to get any writing done: keep your butt in the chair. I try, sitting for much of the day at my computer. But I also sit at the kitchen table, in front of the TV, and sometimes in planes, trains or automobiles. “If you look at people’s lives, what do they do? They just sit,” says Neville Owen, a behavioral epidemiologist at the Center for Urban Transitions at Swinburne University of Technology in Melbourne. Many adults sit for more than half the time they are awake. Typically that’s almost eight hours—and as many as 11.5—out of 16.
According to a growing body of research, the health problems associated with sitting—heart disease and diabetes, to name two—aren’t simply the result of these extensive periods on our keisters. The hazards are greatest when it is uninterrupted time: eight hours can be okay if people break it up by standing and moving around every hour—or if they exercise more vigorously when they are up.
Studies of sedentary behavior began decades ago by linking self-reported time spent watching television to a person’s level of obesity. The research has progressed to include sophisticated devices capable of measuring not just steps but a lack of them. Those studies show that too much sedentary time, especially for prolonged uninterrupted periods, impairs glucose metabolism and is associated with a higher risk of type 2 diabetes. A 2024 study published in JAMA Network Open of nearly half a million people in Taiwan found a 16 percent higher risk of death from any cause and a 34 percent higher risk of cardiovascular disease for those who predominantly sit at work compared with those who don’t. And a 2022 analysis in JAMA Oncology of 1,535 cancer survivors found that those who sat more than eight hours a day and reported no physical activity had the highest death risk both generally and from cancer specifically. (The researchers selected health characteristics to minimize the possibility that illness caused the sedentary behavior in the first place.)
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In recent years overheated headlines have gone so far as to call sitting “the new smoking.” It isn’t quite, experts say. The risk of death from all causes is many times greater for people who smoke heavily than it is for those who sit the most. But sitting is a serious health concern, and public health institutions such as the World Health Organization have begun adding recommendations to spend less time sitting to their physical activity guidelines.
People in the top 25 percent of exercisers can sit for more than eight hours per day without increasing risks.
Those health guidelines also urge 150 to 300 minutes of moderate physical activity per week, which could include working out at the gym or going for a jog or a brisk walk. That raises an important point: even with other regular physical activity, too much sitting can still do harm. “It is possible to be both physically active andsedentary,” says Lin Yang, a research scientist in the Department of Cancer Epidemiology and Prevention Research at Alberta Health Services in Canada and co-author of the 2022 cancer study. Anyone who exercises regularly—as I do—but also sits for work has this risk.
Sedentary behavior is defined as a waking behavior that involves very low energy expenditure (sitting, lying, reclining). Scientists are still teasing out why it is so bad for us, but there are some likely reasons. Sitting—that is, a lack of movement—affects vascular function (particularly in the legs), blood pressure, blood glucose, cerebral blood flow and inflammation. “Patterns of being active or not being active are just so fundamental to our biology. You see them manifested in almost every system,” Owen says.
One solution is to exercise even more overall, says physical activity epidemiologist Ulf Ekelund of the Norwegian School of Sport Sciences, who has studied the combined effects of sitting time and physical activity. “Physical activity can mitigate the effects of prolonged sitting,” Ekelund says. “If you have to sit for long hours, you should try to be physically active above the recommended levels.” Research indicates that people who rank among the top 25 percent in terms of time spent exercising can sit for more than eight hours a day without increasing their risk of premature mortality.
It is also important to break up time spent sitting with some movement, although scientists haven’t yet pinpointed exactly how much is necessary. Our bodies work hard just to rise from a sitting position or vice versa. “Standing from sitting is so biologically active,” Owen says. Experimental studies suggest a dose-response relation between time spent sitting and time spent moving. If you are going to stand up for only a minute, you should probably do so every half hour or so, Owen says. If you are going to walk around for a few minutes, then every hour would suffice.
Standing desks, not surprisingly, reduce sitting time for office workers, but the evidence for health benefits is limited and applies only to the workplace. Long periods spent standing can bring their own complications, such as varicose veins. “Really, it’s about movement,” Owen says.
The bottom line is to change your bottom time. This is far simpler than using fancy desks or ergonomic chairs and computer stands, although those things have their place. What the vast majority of adults and children need to do is move more and sit less.
This is an opinion and analysis article, and the views expressed by the author or authors are not necessarily those of Scientific American.