First, you will have leads (wires) to an ECG machine attached to your chest and a blood pressure cuff is placed on your arm. A clothespin-like sensor may be placed on your finger to measure the amount of oxygen in your blood. After a baseline ECG is obtained you will be asked to begin performing a low level of exercise by walking on a treadmill. The exercise is “graded” – that is, every three minutes, the level of exercise is increased. At each “stage” of exercise, your pulse, blood pressure and ECG are recorded, along with any symptoms you may be experiencing. Maximal vs Submaximal With a “maximal” stress test, the level of exercise is gradually increased until you cannot keep up any longer because of fatigue or until your symptoms (chest pain, shortness of breath, or lightheadedness) prevent further exercise or until changes on your ECG indicate a cardiac problem. Maximal stress tests should be performed when the goal is to diagnose the presence or absence of CAD. With a “submaximal” stress test, you will exercise only until a pre-determined level of exercise is attained. Submaximal tests are used in patients with known CAD, in order to measure whether a specific level of exercise can be performed safely. After the test, you will be monitored until any symptoms disappear, and until your pulse, blood pressure and ECG return to baseline.