The Physical Benefits of Exercise in Strengthening Your Cardiovascular System

Although it is no bigger than your clenched fist, your heart is able to pump more than two thousand gallons of blood through sixty thousand miles of blood vessels each day. To do this, your heart beats more than one hundred thousand times each and every day of your life. Your heart is incredibly strong, but exercise training will make it stronger and more durable. A healthy heart pumps about five quarts of blood a minute while you are resting quietly. When you dash to make that bus, your heart rate may double or even triple, and the remarkable little muscle will pump out up to twenty quarts of blood a minute. Diseased hearts can't match this performance, but exercise-trained hearts can do much more. At maximum effort, an athlete's heart can pump up to forty quarts of blood a minute, and it can sustain a high workload for much longer than the unconditioned heart can.

How does regular exercise help your heart? Like your other muscles, your heart muscle gets larger and stronger with exercise. Exercise also makes the heart muscle more efficient, so it needs less oxygen for itself. Exercise training helps human hearts resist arrhythmias, including the abnormal pumping rhythms that can lead to sudden death. And moderate exercise will earn all of these heartfelt improvements for you.

For poets, the heart symbolizes emotion, for soldiers, courage, and for lovers, romance. But for physiologists, the heart is simply a pump. Its job is to pump oxygen- and nutrient-rich blood to all your body's tissues; your arteries provide the delivery system that makes it possible. Doctors used to think of arteries as passive conduits for blood, working for your body the way a garden hose works for your lawn. Wrong! In fact, arteries are complex structures with crucial regulatory functions, and they are in the front line of the battle for cardiovascular health.

Every artery has three layers in its wall. New research has focused on the inner layer, which is composed of a thin layer of endothelial cells that are in direct contact with the bloodstream. Endothelial cells have a crucial role in vascular health, and exercise training has an important effect on them. Among other things, endothelial cells produce nitric oxide, which has two crucial functions. It keeps the arterial lining smooth and slippery, preventing damaging inflammation and artery-blocking blood clots. In addition, it relaxes the smooth muscle cells of the artery wall's middle layer, preventing spasms and keeping arteries open. Even in health, age takes a toll on endothelial cells, reducing nitric oxide production so that arteries become stickier, stiffer, and narrower. Exercise training boosts nitric oxide production, keeping arteries supple and young. And here's more good news: you don't have to start young or push yourself hard to get these benefits. For example, when scientists from the University of Colorado studied healthy but sedentary men with an average age of fifty-three, they found that a walking program produced dramatic gains in endothelial function in just three months.

Exercise will help keep you and your heart and arteries young. It will also keep your heart and arteries healthy. The inner and middle layers of the artery wall are the battlegrounds of atherosclerosis, the disease responsible for heart attacks, most strokes, and many cases of kidney failure and for peripheral artery disease, which can lead to gangrene and amputations, usually in the legs and feet. As you'll soon see, exercise fights atherosclerosis, protecting you from heart attacks and strokes of many cardiovascular diseases.
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