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More evidence that sitting too much is bad even if you exercise

January 16th, 2011

One of the most surprising bits of research to emerge last year was the finding that too much sitting can be very bad your health, no matter how much exercise you do. In other words, going to the gym every day can’t undo the damage done by sitting in front of a computer all day then laying on the couch all evening.

The trickle of research that started last year is now becoming a flood — for example, I noticed two more studies released in the last few days. One, in the American Journal of Cardiology, reported the following:

Data show that compared to people who spend less than two hours each day on screen-based entertainment like watching TV, using the computer or playing video games, those who devote more than four hours to these activities are more than twice as likely to have a major cardiac event that involves hospitalization, death or both.

The other, in the European Heart Journal, puts a more positive spin on how to mitigate the risks of prolonged sitting:

“Our research showed that even small changes, which could be as little as standing up for one minute, might help to lower this health risk. It is likely that regular breaks in prolonged sitting time could be readily incorporated into the working environment without any detrimental impact on productivity, although this still needs to be determined by further research…”

This whole topic is still a little bewildering for those of us who’ve grown up thinking that getting enough daily exercise means you’re not “sedentary.” Fortunately, just last week Travis Saunders of Obesity Panacea did a nice job of explaining what’s currently known about the science in this area in a guest post at Scientific American. For example:

But what I find truly fascinating is that sedentary behavior also results in rapid and dramatic changes in skeletal muscle. For example, in rat models, it has been shown that just 1 day of complete rest results in dramatic reductions in muscle triglyceride uptake, as well as reductions in HDL cholesterol (the good cholesterol). And in healthy human subjects, just 5 days of bed rest has been shown to result in increased plasma triglycerides and LDL cholesterol, as well as increased insulin resistance—all very bad things. And these weren’t small changes—triglyceride levels increased by 35%, and insulin resistance by 50%!

[...] What is most interesting to me personally is that these physiological changes in skeletal muscle have little or nothing to do with the accumulation of body fat, and occur under extremely rapid time-frames. This means that both lean and obese individuals, and even those with otherwise active lifestyles, are at increased health risk when they spend excessive amounts of time sitting down.

Travis’s whole post is definitely worth a read, as its puts the whole body of research into context (and there are some good questions and answers in the comments section).