Tuesday, April 19, 2011

Is Sitting a Lethal Activity?

DR. LEVINE’S MAGIC UNDERWEAR resembled bicycle shorts, black and skintight, but with sensors mounted on the thighs and wires running to a fanny pack. The look was part Euro tourist, part cyborg. Twice a second, 24 hours a day, the magic underwear’s accelerometers and inclinometers would assess every movement I made, however small, and whether I was lying, walking, standing or sitting. James Levine, a researcher at the Mayo Clinic in Rochester, Minn., has an intense interest in how much people move — and how much they don’t. He is a leader of an emerging field that some call inactivity studies, which has challenged long-held beliefs about human health and obesity. ...

His initial question — which he first posed in a 1999 study — was simple: Why do some people who consume the same amount of food as others gain more weight? After assessing how much food each of his subjects needed to maintain their current weight, Dr. Levine then began to ply them with an extra 1,000 calories per day. Sure enough, some of his subjects packed on the pounds, while others gained little to no weight.

“We measured everything, thinking we were going to find some magic metabolic factor that would explain why some people didn’t gain weight,” explains Dr. Michael Jensen, a Mayo Clinic researcher who collaborated with Dr. Levine on the studies. But that wasn’t the case. Then six years later, with the help of the motion-tracking underwear, they discovered the answer. “The people who didn’t gain weight were unconsciously moving around more,” Dr. Jensen says. They hadn’t started exercising more — that was prohibited by the study. Their bodies simply responded naturally by making more little movements than they had before the overfeeding began, like taking the stairs, trotting down the hall to the office water cooler, bustling about with chores at home or simply fidgeting. On average, the subjects who gained weight sat two hours more per day than those who hadn’t. ...

for most of us, when we’re awake and not moving, we’re sitting. This is your body on chairs: Electrical activity in the muscles drops — “the muscles go as silent as those of a dead horse,” Hamilton says — leading to a cascade of harmful metabolic effects. Your calorie-burning rate immediately plunges to about one per minute, a third of what it would be if you got up and walked. Insulin effectiveness drops within a single day, and the risk of developing Type 2 diabetes rises. So does the risk of being obese. The enzymes responsible for breaking down lipids and triglycerides — for “vacuuming up fat out of the bloodstream,” as Hamilton puts it — plunge, which in turn causes the levels of good (HDL) cholesterol to fall.

Hamilton’s most recent work has examined how rapidly inactivity can cause harm. In studies of rats who were forced to be inactive, for example, he discovered that the leg muscles responsible for standing almost immediately lost more than 75 percent of their ability to remove harmful lipo-proteins from the blood. To show that the ill effects of sitting could have a rapid onset in humans too, Hamilton recruited 14 young, fit and thin volunteers and recorded a 40 percent reduction in insulin’s ability to uptake glucose in the subjects — after 24 hours of being sedentary.

Over a lifetime, the unhealthful effects of sitting add up. Alpa Patel, an epidemiologist at the American Cancer Society, tracked the health of 123,000 Americans between 1992 and 2006. The men in the study who spent six hours or more per day of their leisure time sitting had an overall death rate that was about 20 percent higher than the men who sat for three hours or less. The death rate for women who sat for more than six hours a day was about 40 percent higher. Patel estimates that on average, people who sit too much shave a few years off of their lives. ...

via Is Sitting a Lethal Activity? - NYTimes.com.

I exercise 20 to 30 minutes a day, but I still sit for about 10 hours average a day. Today I worked 14 stressful seated hours.  Not sure how to change that... we need computers that allow us to roam around... and I need some workaholics anonymous sessions.

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