A quick calculation to try
Before you read on, quickly work out how many hours you spent sitting yesterday. Start with breakfast. Then the journey to work, university or school, by car, bus or train. Add the hours at your desk, in the lecture hall or in meetings, lunch break and dinner. And in the evening, perhaps the sofa with a series or your phone.
How much did it add up to? Many people end up at ten hours or more, which is exactly the average. According to a large survey, adults in Germany sit for around ten hours on a working day, almost two hours more than ten years ago. That is more time than most people sleep at night.
Your chronological age counts the years since you were born. Your biological age, on the other hand, describes the actual condition of your body, for example how elastic your blood vessels are and how well your cells still renew themselves. What do all these hours of sitting do to that condition?
Blood vessels: What happens in your legs when you sit
Think of a stream. As long as the water flows, it stays clear. If it gets dammed up and the water stands still for days, it turns murky.
Your blood vessels work in a similar way. Their inner walls depend on blood flowing briskly along them. This flow stimulus prompts them to release messenger substances that keep the vessels wide and elastic. When you sit, however, blood flows slowly in your legs, and the vessels are also kinked at the hips and knees. The stimulus is missing.
An experiment in the USA showed how quickly this becomes noticeable. Eleven young, athletic adults sat for three hours straight. With one leg, they were asked to fidget at regular intervals, for one minute followed by a four-minute break. The other leg stayed still. After the three hours, the vessels in the still leg could widen considerably less well than before. In the fidgeting leg, by contrast, there was no sign of this; the vessels even worked slightly better than at the start.
It is remarkable that these were young, fit people and that simply jiggling a foot was enough.
Your blood vessels do not need much. Above all, they need regular movement, including in between.
If blood vessels become stiffer over the years, the heart has to work harder and organs are less well supplied. You can find out more about the role of blood vessels in your biological age here (Article: Endurance). But do the traces of sitting also reach all the way into the cells?
Telomeres: What less sitting changes in your cells
A team at the Karolinska Institute in Stockholm set out to answer this question. They followed 49 overweight people aged around 68 who had previously done little exercise. Some of them were given a personal exercise programme for six months. Before and after, the researchers measured the telomeres, the protective caps at the ends of the chromosomes that get shorter with every cell division. Read more here (Article: Biological age).
The result was surprising. Among the participants in the programme, the change in telomeres depended mainly on one factor: those who had reduced their sitting time the most actually had longer telomeres afterwards. For the time someone spent on dedicated training, by contrast, no such link appeared.
The study was small, but its result fits with what vascular research shows.
For your biological age, it is not only how much exercise you do that counts, but also how much you sit.
Is sitting the new smoking?
You may have come across this phrase before. It is catchy, but it exaggerates considerably. Researchers from Canada and Australia examined the comparison closely in 2018. Their conclusion: smoking weighs many times more heavily than long periods of sitting. So long hours of sitting are no reason to panic. But it is still a lever worth pulling.
An analysis of more than a million people shows how much activity it takes to offset long periods of sitting. For people who were active at a moderate pace for 60 to 75 minutes a day, for example by brisk walking or cycling, even more than eight hours of sitting a day hardly mattered any more. That is, however, more than most people manage. And it makes clear why training three times a week does not automatically offset a long day at the office: 150 minutes a week is around 20 minutes a day. Everyday life decides the remaining hours.
Balance and flexibility: What hardly stands out in everyday life
Everyday movement includes two abilities that you rarely notice consciously until they are missing. Try it quickly: stand on one leg, with the other leg loosely bent and your arms hanging by your sides. Can you manage ten seconds without wobbling or holding on?
A team from Brazil carried out exactly this test with more than 1,700 people aged between 51 and 75. About one in five could not manage the ten seconds, and the proportion rose considerably with age. Those who passed the test lived longer on average over the following years.
Balance and flexibility are easy to train, and you can do it on the side. Stand on one leg while brushing your teeth, put your socks on standing up or stretch for a few minutes while the coffee is brewing. Together with strength, this is the best protection against falls in old age. Read more here (Article: Strength training).
How to bring more movement into your everyday life
Since 2020, the World Health Organization has explicitly recommended limiting sitting time and replacing it with activity of any intensity. So light movement counts too. A good rule of thumb: get up for a minute or two at least every 30 to 60 minutes.
This is easiest if you link movement to something you do anyway. Take phone calls standing or walking, fetch a glass of water after every meeting, and stand on your tiptoes while the coffee machine is running. On your way to work, get off one stop earlier or take the bike, and in the building take the stairs instead of the lift. If you work from home, you can set a timer, because fixed triggers work more reliably than good intentions.
None of these habits feels like exercise, and that is exactly where their strength lies. They fit into any day and add up over weeks and years.
For your biological age, what counts is not only the workout in the evening, but every hour in which you are not sitting still.
Where you stand on everyday movement
How much you move in everyday life and how your balance and flexibility are doing are two of the questions in the BioAge test. Together with the other questions, they produce an estimate of your biological age and an overview of where you have the most to gain.
Frequently asked questions about sitting and biological age
Does a standing desk help?
Yes, if you use it to switch positions. Standing for hours, however, is not movement: in a large British study, standing more on its own did not lower the risk of cardiovascular disease. Switching between sitting, standing and a few steps is best.
How many steps a day make sense?
The famous 10,000 steps originally come from a Japanese advertising campaign for pedometers. A large analysis of 15 studies shows: from the age of 60, the benefit was largely reached at around 6,000 to 8,000 steps, and for younger people at around 8,000 to 10,000. Every additional step up to that point is worth it.
Do I have to sit up straight?
Less than is often thought. Physiotherapy experts stress that there is no single correct sitting posture. What matters is changing your posture regularly. So the best posture is your next one.
Do housework and gardening count as exercise?
Yes. Vacuuming, hanging up the washing, carrying shopping or weeding interrupt sitting and get your circulation going. For endurance and strength you need a bit more effort on top, but for your blood vessels every movement counts.