The evidence is overwhelming — sitting for long stretches of time can damage your health and a new study could tell us why. Researchers from Indiana University found it takes just one hour of sitting to decrease the blood flow from your legs to your heart by 50 percent. When you're parked in a chair, the muscles in your lower body don't contract to pump blood to the heart as effectively as they should, causing blood to pool in your legs. Eventually, this can lead to impaired blood vessel function — an early marker of heart disease.
And because many of us sit at a desk for at least eight hours a day, the damage done by sitting throughout each day could be even greater, says study author Saurabh Thosar. But there's an upshot — Thosar and his team discovered you can counteract the damage of sitting by taking five-minute walks every hour.
They asked a group of healthy men aged 20 to 35 to sit for three hours without moving their legs. Measuring the guys' arterial function every hour with a blood pressure cuff, they found that the ability for their arteries to expand and pump blood was reduced by 50 percent after the first hour.
The men then sat for another three hours, but took a slow five-minute walk (two miles per hour) every hour. This time, the tests showed no decrease in arterial function. "Five-minute walks prevented the decline of blood flow and arterial function during sitting," says Thosar. "[Walking] does not erase the effect of sitting, per se. Rather, it just does not allow sitting to be as harmful."
The jury's still out on whether you need to walk for at least five minutes to get these benefits or if a one- or two-minute stroll can stifle at least some of sitting's negative effects. Another question is if walking for more than five minutes or picking up your pace will help even more. "I do not have data to prove it, but my feeling is that even shorter walks or taking more breaks will be helpful as long as blood flow increases," says Thosar.