Sitting all day: what ten hours in a chair does, and what offsets it
Sitting for more than eight hours a day is associated with a higher risk of early death, and the association weakens as daily physical activity rises. In a pooled analysis of data from more than one million adults, published in The Lancet in 2016, the increased risk linked to long sitting was eliminated in people who did about 60 to 75 minutes of moderate-intensity activity a day. Those who sat for long hours and were inactive had the highest risk. The World Health Organization accordingly asks adults to limit sedentary time, to replace it with activity of any intensity, and to aim above the minimum of 150 minutes a week when they sit a great deal. For someone whose work means ten hours in chairs, cars and aircraft, the practical answer has two parts: train properly, and break up the sitting.
Your sitting against your activity
Count every seated hour of a normal working day: desk, meetings, car, meals, evening. Then the minutes of at least moderate activity.
- Hours seated per week
- 70
- Activity per week
- 210 minutes
- Reading
- More than 8 hours sitting with under 60 minutes of activity: the highest-risk group in the pooled data
Based on the groups of the 2016 pooled analysis. An association in populations, not a prediction for one person.
What the research measured
The study by Ekelund and colleagues combined sixteen studies in which sitting time and physical activity had been recorded and participants followed for years. The reference group sat for less than four hours a day and was in the most active quarter.
Three findings matter for people at desks.
- Among the least active, mortality rose steadily with sitting time.
- Among those doing 60 to 75 minutes of moderate activity a day, sitting more than eight hours was not associated with higher mortality.
- Television viewing time showed a stronger association than total sitting, and high activity attenuated it without removing it. The reasons are debated; what people eat and drink in front of a screen is one candidate.
These are observational data, based largely on self-report, so they cannot prove cause. They are consistent, though, with trials showing that interrupting sitting improves blood sugar and blood pressure in the short term.
Why sitting is not simply the absence of exercise
Someone can meet the exercise guideline and still be sedentary: forty minutes on a bike at six in the morning, followed by eleven hours seated. The two behaviours are measured separately in the guidelines for that reason.
During prolonged sitting, the large muscles of the legs are inactive, and the mechanisms that clear glucose and fat from the blood slow down. Blood flow in the legs falls. Hips and upper back stiffen in the positions held longest, which is where many of the aches of desk workers originate.
How much activity it takes
Sixty to seventy-five minutes a day is about the top of the World Health Organization's range, or beyond it: 420 to 525 minutes a week against a recommended 150 to 300. Few people in senior roles train that much.
The figure does not have to be met by formal training alone. Moderate activity of every kind counts.
- A brisk 20-minute walk to or from the office.
- Stairs taken at pace.
- A walking meeting. See daily steps.
- A 40-minute training session.
The calculator above takes your daily sitting and activity and places you against the groups of the pooled analysis.
Breaking up the day
The second lever is to interrupt sitting. The World Health Organization's guidance is deliberately simple: replacing sedentary time with physical activity of any intensity, including light, provides health benefits.
- Stand for calls. Most people take ten or more a day.
- Move every hour. Two to three minutes of walking or stairs. Set a recurring reminder for the first month; after that it becomes habit.
- Hold short meetings standing. They end sooner.
- Walk for one-to-one conversations that do not need a screen.
- Put the printer, the water and the coffee at a distance.
- Use a height-adjustable desk for part of the day. Standing still for hours is not the aim; changing position is.
In cars and aircraft
Travel is sitting without the option of standing up. On flights of more than four hours, walk the aisle every hour or two when it is permitted, and flex the ankles in between: long immobility is also a risk factor for blood clots in the legs. On long drives, stop every two hours.
After a day of travel, a twenty-minute walk on arrival does more for stiffness and for sleep than going straight to the room. See jet lag and training.
What sitting does to the way you move
Hours in a chair shorten the hip flexors and round the upper back. This shows up in the gym as a squat that tips forward and shoulders that cannot press overhead comfortably.
Five minutes before any training session is well spent on the following.
- A hip flexor stretch, 30 seconds each side.
- Thoracic rotations on all fours, ten each side.
- Glute bridges, fifteen repetitions.
- Wall slides or band pull-aparts, fifteen repetitions.
See strength training for executives.
Standing desks, treadmill desks and gadgets
A standing desk changes posture and slightly raises energy expenditure. It does not replace exercise. Treadmill desks add steps at the cost of typing accuracy; they suit reading and calls. Wearable reminders work for those who obey them.
None of these is necessary. A calendar reminder and a habit of standing for calls achieve most of the benefit at no cost.
Putting it together
A realistic day for someone with a full diary:
- 06:30: 40 minutes of training.
- 09:00 to 13:00: stand for calls, three minutes of movement each hour.
- 13:00: a 15-minute walk after lunch.
- 14:00 to 19:00: one walking meeting, the rest as in the morning.
That adds up to about 80 minutes of activity and far fewer uninterrupted hours in a chair, without a single extra hour taken from work.
People with back pain, circulation problems or a history of blood clots should take medical advice on how to sit, stand and travel.
Questions
How many hours of sitting a day is too many?
There is no agreed threshold, but risk rises with duration. In a pooled analysis of over a million adults, sitting more than eight hours a day was associated with higher mortality in people who were not physically active. The World Health Organization gives no number and advises limiting sedentary time and replacing it with activity of any intensity.
Does exercise cancel out sitting all day?
Largely, if there is enough of it. In the pooled data, the higher mortality associated with long sitting was no longer observed in people who did about 60 to 75 minutes of moderate-intensity activity a day. Thirty minutes a day reduced the risk without eliminating it. Breaking up sitting through the day adds a further benefit.
Is a standing desk worth it?
It helps you change position, which reduces stiffness and breaks up long periods of sitting. It does not count as exercise, and standing still for hours brings its own discomfort. Alternating between sitting and standing, and walking for a few minutes each hour, achieves more than standing all day. A desk is useful, not necessary.
Sources
- Ekelund et al.: does physical activity attenuate the association of sitting time with mortality? (Lancet, 2016)
- World Health Organization: guidelines on physical activity and sedentary behaviour (2020)
- World Health Organization: physical activity, key facts
- NHS: physical activity guidelines for adults aged 19 to 64