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Can sitting too long kill you?

Friday, April 24, 2009 Posted by Travis Saunders
Photo by independentman.

Ok, so the title of today's post is a little over the top, but stick with me on this. Over the past few years research has suggested that being sedentary (e.g. sitting or lying down) for extended periods of time has a negative impact on your health. We know that people who sit for long periods of time are less likely to be physically active, and more likely to be obese, so it's not that surprising that people who sit for extended periods of time would have increased health risk relative to people who sit less. But new research is suggesting that people who spend more time seated are at increased health risk even after control for these other factors. In other words, no matter your body weight or how much you exercise, if you also spend a lot of time sitting, you are likely to have a higher health risk than someone who performs the same amount of exercise but spends less time sitting.

A new study by Canadian researchers published in this month's Medicine and Science in Sport and Exercise looks at this very topic. The study, available here, was performed by Peter Katzmarzyk and colleagues at the Pennington Biomedical Research Center, and examined the links between time spent sitting (at school, work, and at home) and mortality in a representative sample of more than 17,000 Canadians. They report that time spent sitting was associated with increased risk of all-cause and cardiovascular disease mortality (there was no association between sitting and cancer deaths). In fact, individuals who sat the most were roughly 50% more likely to die during the follow-up period than individuals who sat the least, even after controlling for age, smoking, and physical activity levels.

But wait - could it be that the people who sit more are only at risk because they also happen to be obese? Unfortunately body weight was only available in a subset of individuals in the present study, making this a difficult question to address. However, the authors did examine the association between sitting and mortality after control for body weight in this subset of individuals, and report that sitting remained a significant predictor of mortality. This suggests that all things being equal (body weight, physical activity levels, smoking, alcohol intake, age, and sex) the person who sits more is at a higher risk of death than the peson who sits less. The authors go on to suggest that sitting for extended periods of time may alter certain physiological processes, such as lipoprotein lipase activity, which could explain the link between time spent sitting and mortality risk.

These findings have far-reaching implications. The vast majority of people in Western society are sedentary throughout the work day. Instead of focussing all our efforts on increasing time spent being physically active, should we instead try to convince people to be less sedentary? Should we drastically restructure our work environments? We also know that when individuals with obesity increase their levels of structured physical activity, they often compensate for this increase in exercise by becoming more sedentary in their leisure time. In obese youth, this compensation is so severe that in some studies children actually burn less calories once they start the exercise intervention! Is this yet another reason to consider new types of physical activity interventions (perhaps those focussing on Non Exercise Activity Thermogenesis) which may avoid this compensatory increase in sedentary behaviors?

This is only one cross-sectional study, and I should mention that it used self-report questionnaires to assess sitting time and physical activity levels. However, it raises several interesting questions, and will hopefully pave the way for longitudinal research on this area in the next few years. I would also like to point out that I first heard of this study on Amby Burfoot's Peak Performance blog, available here. Have a great weekend.

Travis

Katzmarzyk, P.T., Church, T.S., Craig, C.L., & Bouchard, C. (2009). Sitting Time and Mortality from All Causes, Cardiovascular Disease, and Cancer Medicine and Science in Sports and Exercise, 41 (5), 998-1005

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3 Response to "Can sitting too long kill you?"

  1. Angela Carter Said,

    How interesting that you have this article here. I fist saw something similar in the Sept. 09 issue of Natural Solution on pg. 18. This prompted me to do some research on this topic and low and behold I found your post. I am writing for my blog to make others aware of the need to get up and move. Thank you so much.

    Posted on October 13, 2009 at 2:49 PM

     
  2. Travis Saunders Said,

    Thanks for the kind words Angela! It's great to hear that you enjoyed the post!

    Travis

    Posted on December 15, 2009 at 11:11 AM

     
  3. Rachel Said,

    hey look, someone made an awesome standing desk! http://www.flickr.com/photos/jen_hansen/5987806107/in/pool-lifehacker-workspace-showandtell#/photos/jen_hansen/5987806107/in/pool-818652@N22/
    Question: is standing too long bad for your back? it sure feels like it :-/ ( PS, currently writing my Masters Dissertation on sedentary time and hemostatic/ coagulation markers... lemme know if you wanna hear what I find out :-) your blog was a great reference for research for me to follow up on!

    Posted on July 30, 2011 at 8:21 PM

     

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We are PhD students in the School of Kinesiology and Health Studies at Queen's University in Kingston, Ontario. Our research focuses on the relationships between obesity, physical activity, and health risk. This blog is our attempt to consider the many "cures" for obesity that we read about on a daily basis. Enjoy.

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The opinions expressed here belong only to Peter and Travis and do not reflect the views of any organization. Any medical discussion on this page is intended to be of a general nature only. This page is not designed to give specific medical advice. If you have a medical problem you should consult your own physician for advice specific to your own situation.

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