If we sit a lot, do we have to move a lot?
Walking for at least 11 minutes a day could reduce the undesirable health consequences of sitting for hours and hours, according to a new study of the ways in which both inactivity and exercise influence how long we live.
For most of us, sitting for prolonged periods of time is common, especially as we face the dual challenges of COVIDrelated restrictions and the shortening days of winter. Not surprisingly, there could be long-term health consequences from this physical quietude.
But how active a person should be if he or she hopes to mitigate the downsides of sitting has remained unclear. If you sit for eight hours at work, for instance, then stroll for half an hour in the evening — meaning you comply with the exercise recommendation of about 30 minutes of exercise most days — is that enough movement to undo most of the health risks of too much sitting?
Some past research suggested the answer is no. A 2016 study involving more than a million people found, instead, that men and women needed to exercise moderately for about 60 to 75 minutes a day in order to diminish the effects of sitting. But that study asked people to remember how much they had moved or sat.
So, for the new study, which was published in a special issue of the British Journal of Sports Medicine, many of the authors of the 2016 review used data from nearly 50,000 people who had worn activity monitors to objectively track how much they moved and sat.
The scientists found that most of volunteers sat a lot, averaging close to 10 hours a day, and many barely moved, exercising moderately, usually by walking, for as little as two or three minutes a day.
The researchers checked death registries for about a decade after people had joined their studies. Dividing people into thirds, based on how much they moved and sat, researchers found that people in the top third for sitting and bottom third for activity had a 260% more likelihood of premature death than the people who moved the most and sat the least.
But people in the middle third for activity, who exercised moderately for about 11 minutes a day, were significantly less likely to have died prematurely than people who moved less, even if all of them belonged to the group that sat the most.
The researchers concluded that the sweet spot for physical activity and longevity seemed to arrive at about 35 minutes a day of brisk walking or other moderate activities, an amount that led to the greatest statistical improvement in life span, no matter how many hours someone sat.
“Brisk walking is excellent moderate exercise.”
Ulf Ekelund, professor of epidemiology and physical activity at the Norwegian School of Sport Sciences