Home > Uncategorized > Too much sitting will kill you, even if you’re fit

Too much sitting will kill you, even if you’re fit

July 29th, 2010

A new study that just appeared online in the American Journal of Epidemiology (abstract here, press release here) adds to the evidence that spending most of the day sitting down has bad effects that aren’t cancelled by daily workouts at the gym. The study looked at 123,000 men and women between 1993 and 2006:

Women who reported more than six hours per day of sitting were 37 percent more likely to die during the time period studied than those who sat fewer than 3 hours a day. Men who sat more than 6 hours a day were 18 percent more likely to die than those who sat fewer than 3 hours per day. The association remained virtually unchanged after adjusting for physical activity level.

It’s that last bit that stings. The obvious question is: how much exercise did the subjects do? In their analysis, the category for “most active” was those who got more than 52.5 MET-hours per week of physical activity (including both day-to-day chores and exercise). According to the ACSM’s Compendium of Physical Activities, running burns anywhere from 7 METs (for “jogging”) to 18 METs (at 5:30/mile). Still, it suggests that the most active people in the study were doing the equivalent of almost an hour a day of jogging, which isn’t insignificant. And the lack of change with respect to physical activity (except at the very lowest level) doesn’t give us much reason to hope that just a bit more exercise — say 100 MET-hours per week — would be any different (though clearly this is a question that should be explored by future studies).

A similar study was covered a few weeks ago by Gretchen Reynolds, and another related study made news back in January, so clearly this result isn’t a one-time fluke. (Interestingly, the study reported by Reynolds focused on men, while the new study found a bigger effect in women — so no one’s immune!) As a committed desk jockey, this is somewhat worrying to me. I’m not quite sure what to do about it. Maybe those standing-desk people aren’t so crazy after all…

  1. Richard Ayotte
    July 29th, 2010 at 12:10 | #1

    I’m a computer programmer so this concerns me tremendously. I’ve done a few things to combat the problem. First, I use this program http://www.workrave.org/ which forces me to get up every 30 minutes. Second, I climb 36 flights of stairs, twice per day during my breaks.

  2. Bradley Young
    July 29th, 2010 at 13:47 | #2

    Nice piece Alex.

    In the academic domain of psychology of exercis/physical activity, many researchers who have long done intervention research to promote physical activity are now switching gears – they are advocating using outcome measures that focus more on eliminating sedentariness and idling behaviour (e.g., screen time in kids, though these measures might very well relate to the issues that you have articulated). The idea is, that from a population health perspective, interventions might be better to eliminate sedentariness than promote physical activity.

    See some musings in a keynote lecture here on the topic:

    http://scapps.org/conference/video-1.php

    I see implications that your piece has for work-place interventions (policy) for people in traditional, white-collar, sitting jobs – more breaks, lunch-hour activity programming, active transport commuting, etc.

    Thanks for an interesting piece,

    Brad

  3. Mark Taber
    July 29th, 2010 at 18:47 | #3

    In the current budget climate (furloughs, pay cuts), getting work to pay for a stand up desk is probably out of the question for me (and I cant afford to eat the cost myself). Frequent stand ups (every 30 minutes)–would they help? And how about using a large exercise ball as a chair?

  4. alex
    July 29th, 2010 at 21:29 | #4

    Thanks for the comments, folks. Mark, my sense is that simply getting out of your chair once or twice an hour and strolling over to the water-cooler would be a great start (perhaps using something like the workrave program that Richard suggested — pretty cool, I’d never seen that!). More generally, I think this is a good reason to think carefully about the dozens of very small decisions we make every day — taking the stairs rather than the elevator, walking down the hall to speak to a colleague rather than e-mailing them, going outside to eat lunch in a park rather than eating at your desk. As Brad points out, this is very different from the usual physical activity interventions that public health experts think about. (Interesting stuff by Stuart Biddle, by the way — thanks for the link!)

    One thing that I should clarify, though (given some of the reaction I’ve seen to this research in other places), is that physical activity is still important! Though I didn’t go into it in the blog entry, the new study also found (as expected) that the more physically active you are, the healthier and less likely to die you become. The key finding is that exercise and sedentary behaviour are two INDEPENDENT risk factors — i.e. that you can’t cancel out nine hours of TV watching by spending an extra 15 minutes at the gym. But you should still exercise!

  5. Anon
    July 29th, 2010 at 22:44 | #5

    An 18% increase of a small number is still a small number.

  6. alex
    July 29th, 2010 at 23:07 | #6

    @Anon: “An 18% increase of a small number is still a small number.”

    That’s actually an excellent point. In this case, though, the number isn’t THAT small, because the subjects were in their early sixties (on average) when the study started in 1992. Ultimately, they observed 19,230 deaths among the ~123,000 subjects in the study — that means, for example, that about 27% of the men in the “most sedentary” category died.

    No one is saying that sitting is the equivalent of smoking two packs a day. It’s certainly going to be a small effect. But this is the third major study this year to reach essentially the same conclusion, so it suggests that there’s something beyond a statistical blip going on here. By no means am I suggesting that everyone should burn their chairs. It’s just something to keep in mind — an excuse to get up and pace around the room for a minute, if nothing else! That’s what I’m going to do right now…

  7. Mark Taber
    August 1st, 2010 at 04:51 | #7

    Great comments, thanks, all. Just wanted to return to let any Macintosh users know about the free version of Apimac Timer (I am not affiliated with them in any way). I have it programmed to speak every 30 minutes, “Get up and move. Get up and move. Step away from the computer. Get up and move.” I have also started taking the stairs, and standing in my office while I’m thinking/working things out.

  1. August 18th, 2010 at 18:53 | #1
  2. January 16th, 2011 at 00:07 | #2
  3. January 26th, 2011 at 10:02 | #3
  4. October 21st, 2011 at 10:51 | #4