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Home  health Exercise and Your Heart |
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Exercise and Your Heart
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Written by suphut
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Tuesday, 19 February 2008 |
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The most important reason to exercise is to strengthen your heart. Along with other muscles, your heart can be trained to do a larger amount of work. Whenever you exert yourself, if only to carry a sack of groceries upstairs, your heart pumps extra oxygen-rich blood to your moving parts, for your muscles need oxygen in order to contract. At first, your heart beats faster and faster to carry more blood (more oxygen) to the arm muscles lifting that shopping bag. However, if you carry groceries every day, after a few weeks your heart and muscles become trained. The heart pumps more blood with each beat, and the muscles use their oxygen more effectively. Eventually, your heart doesn't need to beat as fast to do the same amount of work.
If, in addition to carrying groceries, you run, bicycle, or do some other sport which provides a high level of training, the exercise stretches the size of the chambers in your heart. The larger chambers pump out more blood with each stroke so, again, your heart is trained to beat slower and your pulse slows down, during exercise and at rest.
( Trip ) EXERCISE AND HEART SIZE
It has been known for at least fifty years that the hearts of well-trained athletes are bigger than those of sedentary people: At first, doctors confused these larger hearts with the enlargements associated with congestive heart failure, but now any physician familiar with sports medicine knows that vigorous exercise increases the size of the heart in one of two ways. In weight lifters and other athletes who emphasize isometric and sudden-burst types of exercise, the muscular walls of the heart become thicker. In distance runners and others who exercise steadily, the chambers of the heart are stretched to hold a greater volume of blood. Either way, the heart responds to exertion by fortifying and strengthening itself to withstand any pressure.
Strenuous exercise helps you control high blood pressure. Instead of causing a sharp rise in both your resting (diastolic) and pumping (systolic) pressures, as it does in untrained bodies, exercise in a trained body raises only the systolic rate. Because the aorta and larger arteries stretch to hold a larger volume of blood, the diastolic pressure in trained athletes during exercise may even become lower than it is at rest. Thus blood vessels remain elastic and the heart doesn't have to overwork.
A study from Tufts University School of Medicine revealed that endurance athletes have thinner blood plasma than sedentary people. (Plasma is the liquid component of blood.) This, again, makes it easier for your heart to pump blood through the small blood vessels in your muscles and near your skin. (Thicker than normal plasma has been found in people with acute and chronic inflammations, rheumatoid arthritis, and tuberculosis. One Australian study even linked it to the spread of some cancers.)
Exercise also trains your body to send extra blood quickly and efficiently only to the muscles you're moving and not willy-nilly to every part of your body.
Even relatively mild exercise such as walking Of climbing a flight of stairs helps dissolve potentially dangerous blood clots. In a study directed by R. Sanders Williams, M.D., at Duke University Medical Center, regular mild physical exercise in men and women stimulated the lining of the blood vessels to release greater amounts of plasminogen activators than when these people were sedentary. (Plasminogen activators stimulate the production of plasminogen, which dissolves fibrin, the stringy clotting blood protein. Clots in important blood vessels cause heart attacks and strokes.) Exercise also lowers the level of ซbad" cholesterol (LDLs) in your blood, raises the level of ซgood" cholesterol (HDLs), and reduces the amount of cholesterol plaque already in your arteries.
( Trip ) JOGGERS WHO DROP DEAD
The sudden deaths of people-mostly men-during jogging or other strenuous exercise have been used as proof that exercise is dangerous for the heart. However, as Dr. Jeffrey Koplan of the Center for Disease Control in Atlanta pointed out in a 1980 article in the Journal of the American Medical Association, "Given the millions of persons now running in the United States, some number of them could be expected by chance to die while running-just as some die while eating, reading, and sleeping."
Pre-menopausal women already have a head start in their defense against coronary artery disease. A 1980 article in the Journal of the American Medical Association estimated that there are probably less than 3,000 heart attacks a year in the United States in women under the age of forty-six, while the Royal College of General Practitioners in Great Britain reported only nine heart attacks in a study review of 200,000 women (and seven of the nine women were taking birth-control pills). After menopause, a woman's risk of heart disease increases, but it never quite matches a man's.
Exercise may slow down the aging process. A study by Dr. John O.Holloszy and colleagues at Washington University School of Medicine in St. Louis showed that middle-aged runners had greater cardiovascular performance than their sedentary age mates and achieved a cardiovascular fitness level only 14 percent lower than that of trackmen in their early twenties-a 4 percent decline per decade of age instead of the 8 percent decline researchers expected. Dr. Ralph S. Paffenbarger, Jr., of Stanford University says his study of 17,000 Harvard University alumni shows that you keep this advantage only if you stay in shape. People who were in good cardiovascular condition in college but became sedentary in later life aged like other sedentary people.
You are an individual biochemically. No one else has the same enzymatic balances, the same digestive, nervous, or circulatory reactions. Exercise can't change the hereditary blueprint you were born with. If your parents lived to a vigorous old age, chances are you will too. If your parents were cursed with high blood pressure, atherosclerosis, or other forms of heart disease, you probably will be too. However,
if you do have a heart attack, your good physical condition will make it milder and may even save your life.
If you are lucky, exercise may even prevent heart disease altogether. It certainly will make your life more fun and more satisfying.
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Last Updated ( Monday, 25 February 2008 )
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