From the study:
Prolonged sitting is considered detrimental to health, but evidence regarding the independent relationship of total sitting time with all-cause mortality is limited. This study aimed to determine the independent relationship of sitting time with all-cause mortality.
... We linked prospective questionnaire data from 222 497 individuals 45 years or older ... to mortality data ...
During 621 695 person-years of follow-up ..., 5405 deaths were registered.... The association between sitting and all-cause mortality appeared consistent across the sexes, age groups, body mass index categories, and physical activity levels and across healthy participants compared with participants with preexisting cardiovascular disease or diabetes mellitus.
Conclusions Prolonged sitting is a risk factor for all-cause mortality, independent of physical activity. Public health programs should focus on reducing sitting time in addition to increasing physical activity levels.
I've left out the numbers ... briefly, if this study is correct and accurate, sitting for more than 11 hours a day measurably reduces lifespan compared to sitting for less than 4 hours a day. For the age group looked at, if you were a long-sitter you had a 40% greater chance of being dead within 3 years than if you sat very little in a given day. This does not mean a 40% chance of being dead ... just 40% more than whatever it was. For lesser differences in sitting time, the difference in mortality risk is lesser as well.
I'm not sure how this translates into practical advice and I'm not sure this study alone provides enough information to answer that question. One way to think about this is as follows: If you sit many hours a day because of your job, how much of that sitting time do you need to change into standing time to make a difference, and can standing alone vs. moving around do the trick? Once that is established, perhaps one could create a standing version of one's workspace.
I know what you are thinking: "I go to the gym for five hours a day so that fixes that problem." Sorry, but no. Apparently (and this is not fully demonstrated, so this is something of a guess) it's the sitting that hurts you, independently of the lack of exercise. Yes, those several hours a week of exercise helps you and makes you healthier, but the sitting itself, if we've got this right, is a bad thing, with negative effects, and if you do too much off that every day you'll die sooner than otherwise.
Suggestions? Comments? Questions? Criticisms? Do you know of other research on this?
Well, I once had a contracting gig where I ended up sitting next to another contractor who had previously worked in insurance underwriting, and he told me that as far as the insurance industry was concerned, the #1 risk factor for early mortality was a sedentary occupation... Worse than smoking.
There was also a documentary on the BBC recently ("Horizon: The Truth About Exercise") which made the same point (amongst others): sitting for long periods is a major health risk, and no amount of additional exercise can fix it. Can't remember the name of the key researcher though.
Some anecdata in support of the idea that sitting for a prolonged period is bad: Lately I have been doing some work on my house, and some of that work requires me to sit on the floor so that I can reach and exert leverage on things at floor level. (Removing stripping and staples from a previously carpeted floor, in case you are curious.) The amount of time I can spend sitting down and doing these tasks without feeling aches and pains as a result is noticeably less than for the parts I can do while standing up (such as painting walls)--basically, I can paint pretty much all day (with lunch and bathroom breaks) and not have a problem, but if I spend more than an hour or so on a sitting down part of the work, I feel the effects. In this case, moving around while seated does not seem to help all that much. But standing up every once in a while (because, e.g., the baseboard trim is interrupted by a doorway) does.
I'm curious how they controlled for exercise -- or what was controlled for*. And how they measured time seated (self-reported versus not).
* I mean, many jobs in which one is standing or walking all day are strenuous, or at least involve walking all day. It seems like someone standing/walking for 8 hours gets more exercise just by her job than a seated office-worker could be expected to get in her free time.
Becca, from what I can tell, "exercise" is when you go and exercise at the gym or run outside or whatever. But yes, I had the same thought; there are all sorts of reasons one sits down for less time, ranging from standing at a counter to running around after a toddler.
But, it might be that the exercise contrast is a bit of a red herring. We are not contrasting activity to non activity, but rather, seeing sitting (not as a lack of activity, but as a combination of things including heart rate regulation, body position, circulation, etc as well as low activity level) as a thing, not as a lack of a thing.
Think of it this way: The more X you do the shorter your lifespan, and on the list of "X" is eating fatty foods, smoking, drinking, and sitting there.
This is an interesting study, although I agree it raises a lot of questions that need to be unravelled. I am reminded of the work done with astronauts, which has found that vigorous exercise is much less effective at preventing health problems than they'd expected, and has proven to be a major obstacle for future long-range exploration. (Not that they'll have difficulty getting applicants even then. Plenty of people would go to Mars even if it meant coming home a cripple. Because, man, its' *Mars*! How do you beat that? On a small scale, it's like the astronauts who hide their dosimeters in the most shielded parts of the spacecraft, so as to avoid exceeding the lifetime radiation limit flight rules and getting stuck with a terrestrial job.)
We know lying down a lot, as with bed rest, is very bad for you. I wonder if sitting a lot is somewhere in the middle between lying a lot and standing a lot.
I have a comment in moderation; not sure why. Short version: I'm reminded of spaceflight research showing that vigorous exercise isn't far less effective than expected in preventing disease in astronauts on long-duration missions. Meanwhile, studies on people under bed rest get results similar enough to orbiting astronauts that they make a good study group for space medicine. So there may be a similar factor at play, and I wonder if sitting all day isn't somewhere between bed rest and a truly active lifestyle.
There are numerous studies as well as an emerging medical research field. Here is an organization that is tying the researchers together.
The bottom line is we have evolved to move around and stand up. Good exercise is very important, but so is moving around a few times an hour when you are awake. The moving, it appears, does not have to be strenuous. Even slow walking or standing for extended periods appears to be healthy. Standing desks make a lot of sense.
Actually I can believe that. From evolutionary point of view, we're not designed to sit 8 hours per day or more...
Hunter gatherers actually spend fairly large amounts of time "sitting around" ... but certainly not 11 hours if one is not sick.
I think reference to the hypothetical Environment of Evolutionary Adaptiveness is a good idea, and my sense (having lived with hunter gatherers for extended periods) is that there is far less than 11 hours of sedentary behavior in a daytime period. But, it is important to make reference to actual time allocation studies (which exist) and not an imagined lifeway.
I will try to remember to dig out the time allocation data and see if I can summarize it here.
This post from earlier this month discussed the differences between uninterrupted sitting versus taking breaks. It includes charts, videos, and links:
Good article, great comments! Recently a book was published tittled Is Your Chair Killing You? on this subject. The book sites studies by Marc Hamilton of the University of Missouri & Dr. James A. Levine of the Mayo Clinic showing that low intensity movements done for short periods over the course of the day as being very effective at reducing the damage done by extended periods of sitting. Our bodies were not designed to sit around all day and the latest research seems to point to regular movement that does not necessarily need to be intense "exercise" as a way to be healthier.
Nothing new, you still don't "get up, stand up":
Is it caused by not moving around or the position? Maybe squatting or lounging Roman-style is not so detrimental to your health.
Maybe, but the Romans are all dead.
There is an info-packed series of illustrations (ehem, infographic) summarizing some of the findings about the effect of prolonged sitting on health (obesity) and life duration. Here's the graphic, aptly titled "Sitting Kills" with some practical advice: http://www.medicalbillingandcoding.org/sitting-kills/
I'm thankful for the insightfull comments, especially #7: sedentary behaviour as a special research field.
Sitting may increase your probability of dying in the next 3 years by 40%, but keeping fit, not being obese and eating healthy decreases your chance of dying by a lot more than sitting a lot.
So let's make this simpler to grasp statistically: If you're 20 you have a roughly 0.05% chance of dying next year. If you increase those 0.05% by 40% you get a chance of 0.07%. Suppose you exercised, keep fit, eat healthy etc. and did the good stuff to avoid typical industrial nation diseases like cardiovascular problems and cancer, you have a say 80% decreased chance of dying next year (number made up).
- Sitting a lot and no exercise: 0.07%
- Not sitting a lot and no exercise: 0.05%
- Sitting a lot and exercising: 0.014%
- Not sitting a lot and exercising: 0.01%
Of course 0.003% sounds a lot less impressive than 40% increase, but then, that doesn't make headlines...
I was going to comment on this thread a couple of days ago. But then I thought, "nah, I'll get up, go outside and work in the garden." :)
Even if the relative risk is small, isn't it still important on a population level, given the massive amount of people with sedentary lifestyles?
Florian, there are three flaws in your argument. 1: The study referenced here looks at older people who have a higher chance of dying to begin with, so the precent changes you cite are artificially deflated. 2: you made the numbers up. 3: You might have missed the point, though I'm not sure the point is valid.
The point, which may or may not be valid, is demonstrated with the idea that sitting time operates independently from exercise time. Sitting is a thing, not a lack of a thing. If that turns out to be a reasonable way to view sitting, then the comparison you are making between sitting and other activities is a little like comparing, say, smoking and driving as risk factors. Driving less does not make the cigarettes you smoked less harmful; they are different things.
Having said that there obviously is a link between hours of exercise and hours of inactivity, so they can't be separated entirely. But the point that sitting itself is potentially harmful if done continuously for many hours is a distinct and separate point, possibly.
It is not clear whether all sitting is detrimental to health or whether sitting in certain context and what we do at the same time as sitting might be the problem.
Therefore an open science project to develop a classification of sedentary behaviours has been launched
http://www.sedentarybehaviourclassification.net, that combines expert consensus but also views of the public
PLEASE TAKE PART IN THE GREAT SITTING TIME FOLKSONOMY
FILL IN THIS SURVEY ABOUT HOW YOU DESCRIBE SITTING http://tinyurl.com/cba3yt8
the SIT collective
Sitting will not directly cause death but exercising is vital for all humans. Everyone world wide should get an amount of exercise daily. Whether it is running, cycling or walking as long as you do something which let the blood flow faster. A well balanced lifestyle, which include some physical activity will increase your lifespan.