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Some people think a large medicine ball makes for healthier sitting. (Staff photo)
You have to hand it to science. There is no conundrum too challenging for practitioners of the scientific method to attack, dissect and conquer. 

Take the scourge of too much sitting, for example. For the last few years, we've been told that spending too much time sitting is as bad as smoking or gulping down huge helpings of Ben & Jerry's.

The problem, of course, is that sitting at your desk all day -- whether working or just eating doughnuts and tweeting -- doesn't do much for your weight or overall fitness levels. 

After all, when people sit, slack muscles do not contract to effectively pump blood to the heart. Blood can pool in the legs and affect the function of arteries, or the ability of blood vessels to expand from increased blood flow.

What to do? Well, you could get a stand-up desk, although standing all day has its drawbacks as well. Or, some personal trainers say, you could substitute a large medicine ball for your chair. The need to constantly keep yourself from rolling off the ball supposedly keeps the blood flowing more effectively, although we don't know of any studies that lend credence to this assertion. 

Get up and move

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There's no idle sitting around (or any other kind) in this office. (Staff photo)
But not to worry -- researchers at Indiana University have found that getting up and walking around may be the answer. They found that three easy -- one could even say slow -- 5-minute walks can reverse the harm caused to leg arteries during three hours of prolonged sitting.

This study is the first experimental evidence of these effects, said Saurabh Thosar, a postdoctoral researcher at Oregon Health & Science University, who led the study as a doctoral candidate at IU's School of Public Health-Bloomington.

"There is plenty of epidemiological evidence linking sitting time to various chronic diseases and linking breaking sitting time to beneficial cardiovascular effects, but there is very little experimental evidence," Thosar said. "We have shown that prolonged sitting impairs endothelial function, which is an early marker of cardiovascular disease, and that breaking sitting time prevents the decline in that function."

The researchers were able to demonstrate that during a three-hour period, the flow-mediated dilation, or the expansion of the arteries as a result of increased blood flow, of the main artery in the legs was impaired by as much as 50 percent after just one hour.

The study participants who walked for 5 minutes each hour of sitting saw their arterial function stay the same -- it did not drop throughout the three-hour period. Thosar says it is likely that the increase in muscle activity and blood flow accounts for this.

Light activity

"American adults sit for approximately eight hours a day," he said. "The impairment in endothelial function is significant after just one hour of sitting. It is interesting to see that light physical activity can help in preventing this impairment."

The study involved 11 non-obese, healthy men between the ages of 20-35 who participated in two randomized trials. In one trial they sat for three hours without moving their legs. Researchers used a blood pressure cuff and ultrasound technology to measure the functionality of the femoral artery at baseline and again at the one-, two- and three-hour mark.

In the second trial, the men sat during a three-hour period but also walked on a treadmill for 5 minutes at a speed of 2 mph at the 30-minute mark, 1.5-hour mark and 2.5-hour mark. Researchers measured the functionality of the femoral artery at the same intervals as in the other trial.

The study is being published in Medicine & Science in Sports & Exercise, the official journal of the American College of Sports Medicine.


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