Happy Ground Hogs Day!
From USA Today…
Your Health: Too much sitting puts the body on idle
1/31/2010 7:34 PM
By Kim Painter, USA TODAY
For decades, scientists have studied exercise. But until recently, they paid little attention to the opposite end of the activity spectrum: the many hours modern humans spend sitting, barely moving at all.
But now the early results are in, and the science of sitting is producing sobering headlines. The bottom line, if you will: Sitting kills.
“The body’s idling state is very, very unhealthy,” says James Levine, an endocrinologist at the Mayo Clinic in Rochester, Minn. “Much like a Ferrari, the human is meant to move.”
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Inertia may be especially hard on the heart: Every hour spent watching TV (an activity that usually involves sitting) was associated with an 18% increase in heart disease deaths and an 11% increase in deaths overall among 8,800 Australians who were followed for six years, according to a recent report published online in Circulation. People who watched TV at least four hours a day were 80% more likely to die of heart disease than those who watched less than two hours a day. (Americans watch an average of five hours of TV a day.)
A Canadian study of 17,000 adults also found a consistent link between chair time and deaths from heart disease: The more people sat, for any reason, the more likely they were to die of heart disease within 12 years even if they were slim and exercised regularly.
“Too much sitting is the not the same as too little exercise,” says Marc Hamilton, a researcher at the Pennington Biomedical Research Center in Baton Rouge.
The Canadian and Australian studies can’t prove sitting kills. It’s possible heavy TV watchers and other chair-bound types have other habits (snacking patterns, for example) that explain the link.
But researchers have other kinds of evidence. Hamilton has attached electrodes to people’s bodies and found that “when people are lounging or sitting, the muscles go silent, like a dead horse. … It’s like seeing a flatline for the brain.” Studies in rats show this muscular shutdown is quickly followed by a dramatic drop in an enzyme that Hamilton calls a “vacuum for fat in the bloodstream.” Hamilton believes artery-damaging fats get a new chance to build up during every period of prolonged sitting. Springing up to jog once a day is unlikely to undo the damage, he says.
But exactly how much time in a recliner or office chair is dangerous? Is three hours of constant sitting worse than six hours broken up by a few pacing phone calls? Are sofa-planted kids as profoundly affected as couch-rooted adults?
Scientists can’t say. Though study results are coming in quickly, “we’re a long way from having the volume of scientific evidence we would ideally have before issuing a set of guidelines,” says Russell Pate, an exercise physiologist at the University of South Carolina-Columbia.
Pate was part of a committee that wrote new physical activity guidelines for adults issued by the U.S. Department of Health and Human Services in 2009. The guidelines prescribe specific doses of moderate to vigorous activity (such as brisk walking and running) and muscle-strengthening exercises. They say nothing about limiting sitting, but future versions might, Pate says.
For now, he and other researchers are comfortable with a broad message: Sit less and move more. Pate says: “Our bodies just weren’t designed to be this inactive.”