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University of Iowa Health Science Relations and
Richard Kerber, MD
Professor of Internal Medicine
First Published: 2000
Last Revised: October 2004
Peer Review Status: Internally Peer Reviewed
If you are planning to start a vigorous exercise program--and are a smoker, have high blood pressure, have high blood cholesterol levels, have diabetes, have experienced chest pain during physical activity, or have a family history of heart disease--you should ask your physician about an exercise stress test, says a University of Iowa cardiologist.
"This test, which also is known as a treadmill test, is valuable because it may reveal the presence of heart disease," says Dr. Richard E. Kerber, professor of internal medicine in the UI Carver College of Medicine. Kerber also is on the staff of UI Hospitals and Clinics.
A cardiac stress test generally follows a thorough physical examination. It involves walking at increasing speed on a treadmill, and shows how a person's heart and blood pressure react to strenuous exercise.
Checking heart function before starting an exercise program is vital because exercise can greatly increase demands upon your cardiovascular system, Kerber says. He explains that all muscles, including the heart muscle, need more oxygen during strenuous exercise. Muscles obtain their oxygen from blood, so the blood flow must increase during exercise to meet the muscles' increased oxygen demand. And your heart must work harder to speed the blood circulation.
A person taking a cardiac stress test mounts a treadmill, grasps hand rails and starts walking slowly. The test becomes increasingly strenuous--as treadmill speed and angle of incline gradually increase--while blood pressure and heart rate are monitored, Kerber explains.
The electrical activity of the heart is monitored with an electrocardiogram (ECG). This requires placing wire monitors on the chest and hips of the exercising person, and the resulting low-level electrical impulses create an ink tracing that "pictures" the heart's activity. The electrical impulses cannot be felt by the person, Kerber notes.
Often ultrasound images of the beating heart--an echocardiogram--are recorded before and immediately after the exercise or the treadmill. Detection of exercise-induced abnormalities of the heart's contraction by the echocardiogram enhances the diagnostic accuracy of the test, Kerber says.
This process may reveal heart conditions--such as angina--that could be aggravated by vigorous exercise, Kerber says. Angina results from a temporary localized inadequacy of blood flow, which reduces the oxygen available to a specific area. This can cause severe constricting chest pains and may be a sign of a serious heart condition that may require further testing and treatment, he notes.
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