Used to evaluate heart function, a stress test requires that a patient exercise on a treadmill or exercise bicycle so that the heart rate, breathing, blood pressure, and feeling of well being are monitored.

When the body is active, it requires more oxygen than when it is at rest, so the heart has to pump more blood. Because of the increased stress on the heart, exercise can reveal coronary problems that aren't obvious when the body is at rest. This is why the stress test (although not perfect) is the best noninvasive "first step" in assessing the health of the heart.

The stress test helps doctors determine how well the heart handles the stress imposed by exercise. It's especially helpful in detecting coronary artery disease, inadequate supply of oxygen-rich blood to the tissues of the heart muscle (ischemia), and determining safe levels of exercise in people...