Health and Fitness Information Center

Stress Test

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The test is a troubleshooting procedure designed to reveal problems that a resting electrocardiogram (ECG) does not. At rest, an ECG may indicate that the heart is receiving sufficient oxygen; but with exertion, as the heart's workload increases, the ECG may reveal signs of an inadequate oxygen supply to certain areas of the heart muscle.

The most common cause is narrowing of coronary arteries caused by the buildup of plaque. Thus, the stress test can help identify an abnormality that might otherwise go undetected until a person experiences chest pain while exercising.

According to the American College of Sports Medicine, you don't need a test if you're under forty-five, are in apparent good health, and have no risk factors for coronary artery disease.

Even if you have risk factors, if you're under thirty-five and have no symptoms of coronary artery disease, you don't need this test. However, when a stress test isn't required for health reasons, some people wish to have it done so that an exercise physiologist can design an individualized workout program for them.

Who should have a stress test?
You should undergo a stress test before starting an exercise program if you are included in the following categories:

-You are forty-five or over. (Even if you have been exercising for years, it's wise to have a stress test when you turn forty-five.)

-You are between thirty-five and forty-four and have at least one risk factor for coronary artery disease. These include an immediate family member (parent, brother, or sister) who developed coronary artery disease before age fifty, smoking, obesity, and an elevated blood pressure or cholesterol level.

-You have cardiovascular or lung disease at any age, or a metabolic disorder such as diabetes or hyperthyroidism. Since the test itself may entail some risk in these cases, you should first consult your physician.

During an exercise stress test, your heart's activity is monitored on an electrocardiography while you work out on an automated treadmill or stationary bicycle, usually for ten to fifteen minutes. Before the test begins, sensors are placed on your chest to transmit signals to the machine; generally, the more sensors the better, with twelve "leads" being preferable. While your pace gradually speeds up, the ECG monitors the changes that occur in the rhythm and electrical activity of your heart; your blood pressure and pulse are also monitored continually. Generally, in a stress test, you exercise until fatigue prevents you from continuing, or until warning symptoms show up. (These may include abnormalities of blood pressure, heart rate or rhythm, or the onset of chest pain, shortness of breath, dizziness, or nausea.)

Administered correctly by a physician or another trained professional, a stress test poses few risks. But the results can be inaccurate, largely because of procedural problems. About 10 to 20 percent of stress tests result in false positives (erroneously indicating heart disease). Even more disturbing, false negatives also occur, and in much higher proportions: 20 to 40 percent. Thus, the results of a stress test shouldn't be analyzed in isolation; they must be evaluated in relations to your age, sex, and medical history.