A stress test is a method of analyzing and verifying the effect of physical exertion on the heart under medical inspection. It helps to provide a clear idea about the health of the patient's heart. A cardiac stress test helps to provide accurate data on the arterial blood flowing to the heart during sessions of physical exercise. When compared to the patient's blood flow patterns at rest, the test reveals imbalance of the blood flow towards the  left ventricular muscle tissue of the heart – the section of the heart that leads the most active role in pumping blood. In most cases, a motorized treadmill is used for exercise, while a stationary exer-cycle is used in some exercise laboratories.

A stress test is done to investigate the causes of angina, the heart's capacity to endure stress, determine exercise levels for those who wish to start working out, and to identify fluctuations in heart rates during physical exercise.

During exercise, healthy coronary arteries dilate more than a blocked artery. This uneven dilation causes more blood to be delivered to heart muscle supplied by the main artery. In contrast, blocked arteries supply less blood, causing the overall blood pressure to remain low. The reduced flow of blood causes these muscles to 'starve' during exercise. By stressing these muscles and observing the results of the stress test, a patient's hypotension (low blood pressure) can be easily diagnosed.