Treadmill Test (TMT): Why It Is Done and What to Expect

A treadmill test, also known as a TMT, exercise stress test or exercise ECG, shows how your heart behaves when it is working harder. It is a common test for people with chest pain or heart conditions. This article explains what MedlinePlus and the NHS say about it.

What is an exercise stress test?

MedlinePlus says an exercise stress test measures how exercise affects the heart. It is also called an exercise treadmill test or exercise ECG. The NHS describes the exercise ECG as a test done in hospital while you walk on a treadmill or cycle, with exercise gradually increasing until symptoms appear or you are too tired.

Why is it done?

According to MedlinePlus, the test may be used:

• To check chest pain for coronary artery disease, meaning narrowed heart arteries
• When angina is getting worse or happening more often
• After a heart attack, angioplasty or bypass surgery
• Before starting an exercise programme if you have heart disease or risk factors such as diabetes
• To spot heart rhythm changes during exercise
• To look further at certain heart valve problems

How to prepare

MedlinePlus suggests:

• Wear comfortable shoes and loose clothing
• Ask your provider whether to take your regular medicines that day, and do not stop any medicine without advice
• Tell your provider if you have recently taken certain medicines for erectile dysfunction, within the past 24 to 48 hours
• Avoid eating, smoking, caffeine and alcohol for at least 3 hours before the test
• Usually avoid caffeine and caffeine-like products for 24 hours, including tea, coffee, chocolate and all sodas, even those labelled caffeine-free

The NHS adds that you should avoid a heavy meal and caffeine before an exercise ECG, and that your chest may need to be shaved and cleaned.

What happens

MedlinePlus explains that around 10 sticky patches are placed on your chest and connected to an ECG monitor. Your resting heart rate and blood pressure are recorded. You then walk on a treadmill or pedal a stationary bike, and the speed, slope or resistance increases about every 3 minutes. Your heart's electrical activity and blood pressure are watched all through.

The test stops if you reach a target heart rate, have worrying chest pain or blood pressure changes, show ECG changes suggesting the heart is short of oxygen, or become too tired or have other symptoms such as leg pain. Monitoring continues for 10 to 15 minutes afterwards. The whole visit takes about 60 minutes.

If you cannot exercise, the NHS says you may be given medicine that raises your heart rate instead.

Risks and how it may feel

MedlinePlus says stress tests are generally safe. You may notice mild stinging from the patches, a squeezing feeling from the blood pressure cuff and sometimes chest discomfort, dizziness, palpitations or breathlessness. Some people may have chest pain, or faint. A heart attack or dangerous irregular heartbeat is rare. People at higher risk are usually already known to have heart problems and are often not given this test. Tell the staff straight away if you feel unwell during the test.

What do results mean?

MedlinePlus explains that a normal result means you exercised as long as or longer than most people of your age and sex, with no worrying symptoms or ECG changes. An abnormal result may show abnormal rhythms during exercise, or ECG changes that suggest a blockage in the heart's arteries. Follow-up tests may include cardiac catheterisation, a nuclear stress test or a stress echocardiogram. Only your doctor can interpret what your result means for you.

When to see a doctor

See a doctor if you get chest pain, breathlessness or dizziness on exertion, so they can decide on suitable tests. Call emergency services at once for chest pain that does not stop, pain spreading to the arms, neck or jaw, or chest pain with sweating, sickness or breathlessness.

In an emergency, call your local emergency number (112 in India, 911 in the United States).