A treadmill test, also known as a treadmill stress test, an exercise stress test, or a cardiac stress test, is done to determine how the body responds to strenuous exercise. Essentially, the test involves making a patient walk on a treadmill while he or she is connected to an electrocardiogram (ECG) machine. While the sensitivity and usefulness of this tests is a bit limited, it is reasonably reliable, and is a lot safer than other, more accurate tests.
If you are at risk of suffering from coronary heart disease, your doctor may recommend undergoing a treadmill test. This will help to evaluate the functioning of your heart by indirectly measuring arterial blood flow to your heart. Blood flow to the heart is measured when you are at rest, and when you are exercising at various levels of intensity. Treadmill testing is a reasonably good indicator of a person's general level of physical fitness, and may sometimes also be used for this purpose. Stress tests have several limitations - due to a number of technical reasons, they are not highly sensitive. They are therefore usually recommended as a preliminary test. If necessary, your doctor may subsequently ask you to undergo other tests that are more accurate and more intense.
You should remember that you will essentially be exercising during the treadmill test. You should therefore wear suitable clothes - your clothes must fit you comfortably, and your shoes should be suitable for walking and jogging. In addition, it is advisable to avoid eating or drinking for a couple of hours before the test. Exerting yourself on a full stomach can lead to nausea. On the other hand, avoid staying hungry for too long, or you may feel weak during the test. If you already have a heart condition and are on medication for it, you should ask your doctor whether the medication needs to be temporarily stopped for a day or two before the test.
First the doctor will attach the electrodes to your chest. The test will begin with a measurement of your heart rate and blood pressure while you are at rest. Next, the measurements will be done with you on the treadmill, first at a mild, warm up speed. The speed will gradually be increased as per an established, safe protocol till you reach a certain heart rate. If the readings are dangerous or if you become excessively unsteady or uncomfortable, the test may be stopped prematurely.