Treadmill Test (TMT)/ Exercise Tolerance Test (ETT)
(Also known as an exercise electrocardiogram,exercise electrocardiography, exercise stress testing or exercise treadmill test).
An exercise ECG is an electrocardiogram that is recorded while you are exercising on a treadmill (a running machine) or on an exercise bike. If you get a chest pain or feel uncomfortable when you are being physically active, this test can help to tell if your symptoms are caused by angina, a type of pain that is usually due to coronary heart disease.
If you already know you have coronary heart disease, an exercise ECG can give more information about how severe your condition is, as it lets doctors see the changes to your ECG ‘wave form’ while you are doing exercise. (The ECG wave form is the pattern of the rhythm of your heart.) It can also help doctors plan your treatment.
If you have recently had heart surgery, an exercise ECG can help doctors decide what level of exercise you should do as part of your cardiac rehabilitation programme.
Getting ready for the test
Wear light, comfortable clothes and shoes. Don’t have a heavy meal before you have your ECG.
Exercise raises your pulse rate. However, this effect shows up less in people who are taking beta-blockers (a type of medicine for the heart).
If you take beta-blockers, the doctor may advise you to stop taking them for one or two days before the test.
Several small sticky patches are put on your chest and connected to an ECG recorder to monitor your heartbeat, in the same way as for the ECG. You will then be asked to exercise, either on a treadmill (a running machine) or on an exercise bike.
The test starts off at a very easy rate and is gradually made harder either by increasing the speed and slope of the treadmill or by putting a brake onto the bike. A doctor or specially trained technician will carefully check your ECG reading, blood pressure and pulse. The staff will tell you when to stop – usually when they have the measurements they need. They may also tell you to stop if you start getting chest pains, or if you get tired or very short of breath. Let them know if you get any of these symptoms. You can also tell the staff if you cannot carry on with the test. They will take more ECG readings after you have stopped exercising.
The exercise test usually lasts between a few minutes and 15 minutes. It can be hard work, but should not be too much for you. Many people are pleasantly surprised by how much they can achieve.
The value of the test is much greater if you try to work as hard as you can. If you cannot do the exercise test because you have another physical condition, such as severe arthritis or lung disease, the doctor may recommend a radionuclide test or a stress echocardiogram instead.
What can the test show?
The exercise ECG shows doctors the pattern of your heart activity during exercise. The doctors also need to know how much exercise you can do. If you feel pain and if there are changes on the ECG when you exercise, this could mean that the pain comes from your heart. This may be more serious if it happens during mild physical activity than if it happens during strenuous exercise.
After the test, you may be told that you have had a ‘positive’ or a ‘negative’ exercise ECG.
- A positive exercise ECG is when significant changes are seen on the ECG during exercise.
- A negative exercise ECG means there are no unusual or obvious changes shown on the ECG during the test.
The exercise ECG is a very useful test, but it is still not 100% accurate. Sometimes people with a normal heart have an exercise ECG that shows changes. (For some unknown reason this often happens with young women.) Sometimes the test may show changes even though the person has very few symptoms. On the other hand, people who do have coronary heart disease may have a normal exercise ECG.
If you have had a heart attack, exercise testing can help doctors find out more about the condition of your heart and plan your rehabilitation. If you have an exercise ECG shortly after a heart attack, the exercise test will be less strenuous. If you have a negative exercise ECG after a heart attack, your risk of having further heart problems is low. It is also reassuring for you to know that you can gradually build up to doing quite vigorous exercise safely.