A stress test, sometimes called a treadmill test or exercise test, helps a doctor find out how well your heart handles work. As your body works harder during the test, it requires more oxygen, so the heart must pump more blood. In a stress test, you walk on a treadmill that makes your heart work progressively harder. An electrocardiogram (ECG) monitors your heart’s electrical rhythms. The doctor also measures your blood pressure and monitors whether you have symptoms like chest discomfort or fatigue. Abnormalities in blood pressure, heart rate, or ECG or worsening physical symptoms could point to coronary artery disease (CAD): fatty deposits (plaques) that reduce the flow of oxygen-rich blood to the heart muscle.