More Evidence That Sitting Is Bad For Us— And Exercise Alone Won’t Save Us
The American Heart Association (AHA) has just released a science advisory on the ills of sitting. The experts who wrote the review sifted through the available evidence on the risks that lack of activity confers on us. Americans, the team finds, sit for six to eight hours a day, on average, and sitting, as a number of studies have found, is linked to all kinds of problems, from diabetes to death. But the larger problem is that exercise alone won’t save us—even people who work desk jobs but are quite active in their leisure time don’t have the same reduced risk of disease and death as people who simply sit less in the first place. Which makes it hard to determine effective exercise guidelines. But, as the team concludes, perhaps the more effective message at the moment would be to sit less, instead of just exercise more.
The review was written up by a team at research institutions all over the country, and published in the AHA journal
The team combed the research out there on sedentary time, exercise, risk of disease and mortality, and found that people have definitely gotten more sedentary over the years: One study they cite reported that the average time people in the U.S. spent sitting rose from 26 hours/week in 1965 to 38 hours/week in 2009. In the UK, it was slightly higher, rising from 30 hours/week to 42 hours/week, respectively.
And as expected, sitting for long periods of time was linked time and time again to diabetes, cardiovascular risk and death. For instance, studies looking at the correlation between TV-watching and diabetes risk have found that each additional two hours of time a person spends watching TV is linked to an increased risk of diabetes by at least 14%, or more. Similarly, the risk of heart disease rises by around 6-8% for every additional hour a person spends watching TV. Finally, people who are the most sedentary have a significantly-higher risk of mortality—sometimes by several times—than those who are the least sedentary.
The bigger problem might be that exercising seems to only partially lessen the blow of sitting too much. It does not completely reverse it. That is, even people with high levels of physical activity in their free time, if they sit a lot otherwise, are still at higher risk than people who sit the least.
So what are we to do? For one, the authors say, we should punctuate our sedentary times quite intentionally, by popping up and stretching or walking a bit every 30 minutes or so. “If you’re already physically active, that’s the most important thing. But it’s good to take breaks from sedentary time, too,” study author Deborah Rohm Young said in a statement. “Instead of powering through your work from the minute you get into the office until lunch break, consider walking around the office a couple of times.”
She and her team also point out in the advisory that asking people to sit less—in addition to simply exercising more—seems to be the most effective message in getting people to change their behavior. So from a public health perspective, there’s a difference in the messages that are transmitted.
There’s been a lot of controversy in what the “right” levels of exercise actually are. Just last week a study suggested that we should be getting quite a bit more than the oft-recommended 150 minutes/week, if we really want to reduce our risk of disease. The authors of this new advisory don’t make new recommendations about the time or type of activity we should try to get in—they arrive at the simple conclusion, “Sit less, move more.” Which is vague, if accurate (and followable) advice.
Perhaps that’s all we need at the moment. Since we don’t know exactly how much exercise we need (and it probably depends on a slew of individual factors), and what activities count as exercise, maybe just reminding ourselves to get up once in a while and move around a bit is enough for now.