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Exercise

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An in-depth report on the benefits and types of exercise.

Exercise's Effects on the Heart

Inactivity is one of the four major risk factors for coronary artery disease, on par with smoking, unhealthy cholesterol, and high blood pressure. However, exercise helps improve heart health in people with many forms of heart disease and can even reverse some risk factors, such as some of the effects of smoking.

Like all muscles, the heart becomes stronger and larger as a result of exercise so it can pump more blood through the body with every beat and sustain its maximum level with less strain. The resting heart rate of those who exercise is also slower because less effort is needed to pump blood.

People who exercise the most often and vigorously have the lowest risk for heart disease, but any exercise is beneficial. Studies consistently find that light to moderate exercise is even beneficial in people with existing heart disease. However, anyone with coronary artery disease should seek medical advice before beginning a workout program.

Circulation of blood through the heart
The heart is a large muscular organ which constantly pushes oxygen-rich blood to the brain and extremities and transports oxygen-poor blood from the brain and extremities to the lungs to gain oxygen. Blood comes into the right atrium from the body, moves into the right ventricle and is pushed into the pulmonary arteries in the lungs. After picking up oxygen, the blood travels back to the heart through the pulmonary veins into the left atrium, to the left ventricle and out to the body's tissues through the aorta.

Heart- and Stroke-Protective Benefits of Exercise on the Heart and Blood

Exercise has a number of effects that benefit the heart and circulation, including improving cholesterol and lipid levels, reducing inflammation in the arteries, assisting weight loss programs, and helping to keep blood vessels flexible and open. Studies continue to show that physical activity and avoiding high-fat foods are the two most successful means of reaching and maintaining heart healthy levels of fitness and weight.

In their 2003 guideline on exercise for the prevention of cardiovascular disease, the American Heart Association recommended that individuals perform moderate-intense exercise for 30 minutes on most days of the week. This recommendation supports similar exercise guidelines issued by the Centers for Disease Control and Prevention and the American College of Sports Medicine.

Coronary Artery Disease. People who maintain an active lifestyle have a 45% lower risk of developing heart disease than do sedentary people. Experts have been attempting to define how much exercises is needed to produce heart benefits. In 2002, a well-conducted study on overweight adults confirmed previous research that reported beneficial changes in cholesterol and lipid levels, including lower LDL levels (the so-called bad cholesterol), even when people performed low amounts of moderate or high intensity exercise (e.g., walking or jogging 12 miles a week). However, more intense exercise is required to significantly change cholesterol levels, notably increasing HDL (the so-called good cholesterol). An example of such a program would be jogging about 20 miles a week. Such benefits in the study occurred even with very modest weight loss, suggesting that overweight people who have trouble losing pounds can still achieve considerable heart benefits by exercising.

Some studies suggest that for the greatest heart protection, it is not the duration of a single exercise session that counts but the total daily amount of energy expended. Therefore, the best way to exercise may be in multiple short bouts of intense exercise, which can be particularly helpful for older people.

Resistance (weight) training has also been associated with heart protection. It may offer a complementary benefit to aerobics by reducing LDL levels. Exercises that train and strengthen the chest muscles may prove to be very important for patients with angina.

Effects of Exercise on Blood Pressure. Regular exercise helps keep arteries elastic, even in older people, which in turn ensures blood flow and normal blood pressure. Sedentary people have a 35% greater risk of developing hypertension than athletes do.

Click the icon to see the risks associated with untreated hypertension.

It should be noted that high-intensity exercise may not lower blood pressure as effectively as moderate-intensity exercise. In one study, moderate exercise (jogging two miles a day) controlled hypertension so well that more than half the patients who had been taking drugs for high blood pressure were able to discontinue their medication. Experts recommend at least 30 minutes of exercise on most -- if not all days. Studies have indicated that yoga and tai chi, an ancient Chinese exercise involving slow, relaxing movements, may lower blood pressure almost as well as moderate-intensity aerobic exercises.

Click the icon to see an image of yoga practice.

Anyone with existing hypertension should discuss an exercise program with their physician. Before starting to exercise, people with moderate to severe hypertension should lower their pressure and be able to control it with medications. They should avoid caffeinated beverages, which increase heart rate, the workload of the heart, and blood pressure during physical activity. Everyone, and especially people with high blood pressure, should breath as normally as possible through each exercise. Holding the breath increases blood pressure.

Effects of Exercise on Heart Failure. Traditionally, heart failure patients have been discouraged from exercising. Now, exercise performed under medical supervision is proving to be helpful for select patients with stable heart failure.

  • Studies continue to report benefits from exercise training. In one study, heart failure patients as old as 91 years old increased their oxygen consumption significantly after six months of supervised treadmill and stationary bicycle exercises.
  • Progressive resistance training may be particularly useful for heart failure patients since it strengthens muscles, which commonly deteriorate in this disorder. Even simply performing daily handgrip exercises can improve blood flow through the arteries.

Experts warn, however, that exercise is not appropriate for all heart failure patients.

Effects of Exercise on Stroke. The effects of exercise on stroke are less established than on heart disease, but most studies are positive on its benefits. The following are some examples:

  • According to one major analysis, men cut their risk for stroke in half if their exercise program was roughly equivalent to about an hour of brisk daily walking five days a week. In the same study, exercise that involved recreation was more protective against stroke than exercise routines consisting simply of walking or climbing.
  • A 2000 study of women also found substantial protection from brisk walking or striding (rather than casual walking).

Starting an Exercise Program for High-Risk Individuals

Anyone with heart disease or risk factors for developing heart disease or stroke should seek medical advice before beginning a workout program. Patients with heart disease can nearly always exercise safely as long as they work out under medical supervision. Still, it is often difficult for a physician to predict health problems that might arise as the result of an exercise program. At-risk individuals should be very aware of any symptoms warning of harmful complications while they exercise.

Some experts believe that anyone over 40 years old, whether or not they are at risk for heart disease, should have a complete physical examination before starting or intensifying an exercise program. Some physicians use a questionnaire for people over 40 to help determine whether they require such an examination:

  • Has any doctor previously recommended medically supervised activity because of a heart condition?
  • Is chest pain brought on by physical activity?
  • Has chest pain occurred during the previous month?
  • Does the person faint or fall over from dizziness?
  • Is bone or joint pain intensified by exercise?
  • Has medication been prescribed for hypertension or heart problems?
  • Is the person aware of or has a doctor suggested any physical reason for not exercising without medical supervision?

Those who answer yes to any of the following questions should have a complete medical examination before developing an exercise program.

Stress Test. A stress test helps determine the risk for a heart event from exercise. Anyone with a heart problem or history of heart disease should have a stress test before embarking on an exercise program. Experts currently also recommend this test before a vigorous exercise program for older persons who are sedentary, even in the absence of known or suspected cardiovascular disease. It is expensive, however, and some experts believe that it may not be necessary for many older people with no evident health problems or risk factors. They recommend instead a carefully monitored program, starting out with low-intensity exercises and gradually building up.

Heart Attack and Sudden Death from Strenuous Exercise

An estimated 1.5 million heart attacks occur every year. Of these, 75,000, or about 5%, occur after heavy exertion, leading to 25,000 deaths.

High-Risk Individuals. In general, the following people should avoid intense exercise or embark on it only with carefully monitoring:

  • Strenuous physical exertion is never recommended for people who suffer from uncontrolled diabetes, uncontrolled seizures, uncontrolled high blood pressure, a heart attack within six months, heart failure, unstable angina, significant aortic valve disease, or aortic aneurysm.
  • Older people should be cautious. Studies report that older people who first embark on vigorous exercise are at slightly higher than average risk for a heart attack during the first year, but over time, regular exercise is likely to reduce this risk.
  • Experts generally recommend that moderate or severe hypertension (any systolic blood pressure over 160 mm Hg or diastolic pressure over 100 mm Hg) should be controlled to lower levels before starting an exercise program.
  • Sedentary people should be cautious. One major study found that sedentary people who throw themselves into a grueling workout increase their risk of heart attack 107 times beyond that which would occur with low or no exertion.
  • Episodes of exercise-related sudden death in young people are rare but of great concern. Some are preceded by syncope (fainting) -- caused by a sudden and severe drop in blood pressure. It should be noted that syncope is relatively common in athletes and is dangerous only in people with existing heart conditions. Young people with genetic or inborn heart disorders should avoid intensive competitive sports.
  • Young athletes sometimes take anabolic steroids or products containing ephedra to enhance performance. It should be noted that such products have been associated with cases of stroke, heart attack, and even death.

The risk for heart attack from exercise should be kept in perspective, however. Some form of exercise carefully tailored to their specific conditions has benefits for most of these individuals. And in many cases, particularly when the only risk factors are being sedentary and older, exercise can often be increased over time until it is intense.

Hazardous Activities for High-Risk Individuals. The following activities may pose particular dangers for high-risk individuals:

  • Intense workouts (snow shoveling, slow jogging, speed walking, tennis, heavy lifting, heavy gardening) may be particularly hazardous for people with risk factors for heart disease, particularly older people. They tend to stress the heart, raise blood pressure for a brief period, and may cause spasms in the arteries leading to the heart.
  • Some studies suggest that competitive sports, which couple intense activity with aggressive emotions, are more likely to trigger a heart attack than other forms of exercise.

Listening for Warning Signs. It should be noted that according to one study, at least 40% of young men who die suddenly during a workout have previously experienced, and ignored, warning signs of heart disease. In addition to avoiding risky activities, the best preventive tactic is simply to listen to the body and seek medical help at the first sign of symptoms during or following exercise. They include the following:

  • Irregular heartbeat.
  • Undue shortness of breath.
  • Chest pain.
Click the icon to see an image of a coronary artery spasm.
Click the icon to see an image of stable angina.
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