The guide

Does a workout cancel a day of sitting?

By GyroscopeUpdated November 14, 20267 sources

A 30-minute workout doesn’t cancel it, but about an hour of brisk moving a day did. In more than a million adults, people who sat over 8 hours a day and moved 60 to 75 minutes had no clear extra risk of death. Hours of TV were harder to offset.

There are two stories going around and they pull in opposite directions. One says sitting is a poison of its own, so even people who work out are slowly hurting themselves at their desks. The other says a morning run takes care of everything, so the next ten hours in a chair don’t matter. The biggest study on the question found something in between, and it puts the weight on how much you move far more than on how much you sit.

The million-person study

In 2016, a team led by the researcher Ulf Ekelund gathered every study they could find that measured both sitting and exercise, and reanalyzed them all the same way. For sitting, that gave them 1,005,791 people followed for 2 to 18 years, and 84,609 of them died. They split people into four groups by hours of sitting a day and four groups by activity, which made 16 combinations, and compared each one with people who sat under 4 hours and moved the most.

The most active group did more than 35.5 MET-hours of activity a week, which the authors translated as “about 60 to 75 min per day” of moderate activity, like brisk walking. In that group, people who sat more than 8 hours a day had no clear extra risk (a hazard ratio of 1.04, with a range that crossed no difference). Sitting time “was not associated with increased all-cause mortality” in the most active quarter at all.

At the other end, the least active people who sat more than 8 hours had 59% higher risk than the reference group. And the least active people who sat under 4 hours still had 27% higher risk. Sitting less didn’t make up for moving too little.

A desk day: about 9 hours of sitting and 20 minutes of brisk moving, with the 40 minutes still to find for about an hour (dotted). Try yours in Does my workout cancel my sitting?

What about TV?

Six of the studies asked about TV, covering 465,450 people. Watching 3 hours or more a day went with higher risk of death whatever people’s activity level, except in the most active group, where the risk only rose at 5 hours a day or more (16% higher). The authors’ conclusion was that an hour or so of activity “attenuates, but does not eliminate the increased risk associated with high TV-viewing time.” Nobody knows yet why TV is harder to offset than sitting at work.

A picture from daily life

Think of a bank account with a monthly fee. If you put in a good amount every month, the fee barely shows. If you put in almost nothing, the fee drains you, and closing the account for a few days a week doesn’t change much.

Sitting is the fee, and moving is the deposit. For people who moved about an hour a day, the hours in the chair barely showed in the numbers. For people who moved very little, sitting less didn’t fix it.

The bus drivers had a point

The first clue about all this came from London’s double-decker buses in the early 1950s, where drivers sat for their whole shift and conductors climbed the stairs all day. The conductors had less heart disease. The conductors’ job combined a lot of moving with little sitting, and it took until 2016, and a million people, to pull those two apart. Everything you need to know about exercise.

Why does moving through the day help?

Part of it happens in your muscles. When a muscle works, it moves sugar transporters to its surface and pulls sugar out of the blood by its own signals, and it pulls hardest while it’s working. A long sit leaves big muscles idle for hours. That’s one reason short walks after meals are popular for blood sugar, and it’s the subject of glucose.guide.

The US guideline’s first line for adults is to “move more and sit less throughout the day”, and its 2018 edition says all physical activity, especially moderate-to-vigorous activity, can help offset the risks of sitting. Short bursts count too. In 25,241 UK adults who didn’t exercise, about 4 minutes a day of hard bursts in daily life, like fast stair climbs, went with 26% to 30% lower risk of death.

Isn’t sitting the new smoking?

What this study can’t tell you

People reported their own sitting and activity, and those reports are rough. Everyone chose how they spent their day, and people who are unwell tend to sit more and move less. The published summary gives the end groups, and the middle combinations need the full paper. None of it gives you a personal risk.