Legs Aid Heart in Pumping Blood

Your heart has the gargantuan task of pushing blood through 60,000 miles of blood vessels. Still, it may come as a surprise to learn that your heart doesn't do the job alone. It gets an important assist from your body's other muscles, especially those in the legs, which play an important role.

Your body has two basic types of blood vessels. Arteries are thick-walled vessels that supply blood to your muscles and organs under pressure supplied by the heart, a fist-sized muscle that weighs about one pound. Veins, on the other hand, have much thinner and less muscular walls and work under much less pressure compared with arteries, according to the American Medical Association.

Veins easily compressed

Because blood flows through veins under low pressure, the veins are easily compressed by even the smallest muscular contractions. This assistance is especially important in the legs, where blood must fight gravity to get back to the heart. In addition, a series of thin, membranous valves spaced at short intervals along the way keeps blood from backing up. It's the alternate compression and relaxation of the veins, as well as the one-way action of their valves, that provides a squeezing motion similar to that of the heart. Activities such as running or walking help move the blood forward through the veins. As a result, when you run, walk, or even just stand, the muscles tend to pump blood up from one section of the vein to the next, according to William D. Suggs, M.D., a vascular specialist in New York City.

"That's why in the Army when standing at attention they teach you to wiggle your toes and feet inside your boots so you don't faint," Dr. Suggs says. The muscular contractions of wiggling your toes are just enough to keep the blood moving up from your feet.

Don't sit for long periods

It's also why you should get up and walk around every so often if you sit for long periods. The simple act of sitting for hours on end can cause blood to pool in your veins and, in some people, cause clots. Clots often have no symptoms, but they can break free and travel until they get stuck in vessels of the lungs that are too small to let them pass. This is known as a pulmonary embolism, says the National Heart, Lung, and Blood Institute. Symptoms include chest pain, shortness of breath, and rapid heart rate. Some pulmonary embolisms can be fatal if the clot is large enough to close a major artery in the lungs or if the clots are numerous.

As long as you're otherwise healthy, it's easy to help avoid problems like this. First and foremost, keep your legs in shape. Walking and bicycling are just two activities that exercise and tone the muscles of the legs.

"People's tendency to clot varies," says Dr. Suggs. "To some extent it's with hereditary. So even young athletes can get clots. But generally the better shape you're in, the less likely you are to suffer them."