f you want to offset the health hazards of sitting at your desk all day, you’ll need to dedicate yourself to an hour of moderate exercise a day, according to a new analysis.
Why it matters:
Previous studies had already shown that lack of physical activity, and spending lots of time sitting, both have negative health effects — including cardiovascular disease, diabetes, cancer, and early death. But nobody had done a systematic review looking at the two combined.
The nitty gritty:
The authors of this meta-analysis used data from 16 different studies to examine the relationship between time spent sitting down, physical activity, and likelihood of dying during a certain period of time. Instead of just using published data, they contacted the original studies’ authors and requested the data broken down in a specific way that would make it possible to combine it together.
They found that individuals who weren’t very active and who also spent at least eight hours a day sitting were 59 percent more likely to die over the next decade, on average, than individuals who spent 60 to 75 minutes a day doing exercise of “moderate intensity” — like brisk walking or bicycling.
They also found that for individuals who were very active, the amount of time they spent sitting down had no effect on their likelihood of dying over the next decade. The findings were published Wednesday in the Lancet.
You should know:
An hour a day is a good deal more than what’s currently advised for adults. Currently, government guidelines say that “most health benefits occur with at least” two and a half hours of physical activity per week. They don’t say anything about time spent sitting.
“Both the sitting piece and the physical activity piece are the two levers we can pull to improve health,” said Charles Matthews, a senior investigator at the National Cancer Institute, who provided some of the data for this analysis.
But keep in mind:
The findings shouldn’t just call for changes in individual behavior, but also policy changes, points out Risa Wilkerson, executive director of the organization Active Living By Design.
People who work two jobs might not have time to exercise an hour a day, Wilkerson said. But if wages were higher, those people might only need to work one job and would have more time to take care of themselves.
The US government is in the process of updating its physical activity guidelines. This study could inform those guidelines, both in terms of how much physical activity to recommend, and how much time people should spend sitting down, said Hannah Arem, a professor at George Washington University’s public health school. And the guidelines in turn may influence doctors’ advice and policies set by insurance companies or workplace wellness programs.
To cancel out the risk of long stretches of sitting, you may need to do more aerobic exercise than current guidelines advise.