A stress ECG, also called an exercise ECG or exercise tolerance test, records your heart's electrical activity while you walk on a treadmill that gradually gets faster and steeper. It shows how your heart copes when it has to work harder, which can reveal problems that a resting ECG may miss. Most people find it straightforward: you wear sticky sensors on your chest, exercise at a pace that starts slowly and builds up gradually, and are watched closely throughout.
What is a stress ECG?
An electrocardiogram (ECG) records the electrical signals that make your heart beat. A standard resting 12-lead ECG takes this recording while you lie still. A stress ECG takes the same recording while you exercise, usually on a treadmill (sometimes on an exercise bike), so your clinician can see what happens to your heart rhythm, heart rate and blood pressure under effort.
Some heart conditions only show themselves when the heart is working hard. For example, a narrowed artery may supply enough blood at rest but not during exercise. That is why a stress ECG can add useful information to other tests.
Why might you need an exercise ECG?
A doctor may suggest a stress ECG to:
- look into chest pain or discomfort, breathlessness or dizziness, particularly if it comes on with activity
- check for signs of coronary heart disease, where the heart muscle may not get enough blood during exercise
- see whether palpitations or an abnormal heart rhythm are triggered by exertion
- check how your heart copes with exercise after a procedure such as a coronary angioplasty (stent)
- help assess fitness for certain jobs or licences, such as professional or taxi and private hire driving
A stress ECG is not right for everyone. If you have very recent chest pain, some valve problems or certain other conditions, your clinician may advise a different test.
How should you prepare for a stress ECG?
Good preparation helps the test go smoothly and gives the most useful result.
- Wear light, comfortable clothes and trainers or flat shoes you can walk briskly in. A top that is easy to take off helps.
- Eat lightly. Avoid a heavy meal for two to three hours before your test.
- Avoid caffeine and smoking. The British Heart Foundation advises avoiding caffeine for two to three hours and smoking for eight hours beforehand, unless you are told otherwise.
- Ask about your medicines. Some heart medicines, such as beta blockers, can change how your heart responds to exercise. Do not stop any medicine unless your doctor tells you to.
- Bring a list of your current medicines and any previous heart test results.
The chest area needs to be clean and dry so the sensors stick well, so avoid body lotions, oils or talcum powder on the day. Some people may need small patches of chest hair shaved.
What happens during the test?
When you arrive, the clinician will explain the test, check your medical history and answer your questions. Then:
- Small sticky sensors (electrodes) are placed on your chest and sometimes your shoulders, and connected to the ECG machine.
- A blood pressure cuff is put on your arm.
- A resting ECG and blood pressure reading are taken first.
- You start walking slowly on the treadmill. Every few minutes the speed and slope increase a little. A common method is called the Bruce protocol, which has stages of three minutes each.
- Your heart rhythm is watched on a screen the whole time, and your blood pressure is checked regularly.
- When you stop, you rest while your heart rate and blood pressure return towards normal, and recordings continue during this recovery period.
You will be asked to say how you feel throughout. Tell the team straight away if you feel chest pain or discomfort, dizziness, very short of breath, too tired, or unwell in any way. The test can be stopped at any time.
How long does a stress ECG take?
The exercise part usually lasts up to around 15 minutes, depending on your fitness and how your heart responds. With preparation, recovery and explanation, you should allow up to an hour for the whole appointment.
| Part of the appointment | What happens |
|---|---|
| Preparation | History, questions, sensors and blood pressure cuff fitted |
| Exercise | Walking on the treadmill as it gradually gets faster and steeper |
| Recovery | Resting while monitoring continues until your heart rate settles |
| Afterwards | Sensors removed; you can usually go home once your heart rate is back to normal and you have got your breath back |
Is a stress ECG safe?
For most people, an exercise ECG is a well-established test. It is carried out under close supervision, and the team will stop the test early if needed. The test itself should not be painful, although you may feel tired, sweaty or a little breathless, as you would with any brisk exercise. You may also notice slight skin irritation where the sensors were. Your medical history is checked carefully before the test to make sure it is suitable for you.
What do the results mean?
Your results look at several things together: how long you exercised, your heart rate and blood pressure response, any symptoms, and any changes on the ECG tracing. A normal result is reassuring. An abnormal or unclear result does not always mean there is a serious problem, but you may be advised to have further tests, such as an echocardiogram or other heart imaging. A clinician will explain what your results mean for you.
If your symptoms come and go, such as palpitations, a longer recording may be more helpful than a short exercise test. Our guide to Holter monitoring explains how this works.
When to get urgent help
A stress ECG is a planned test, not an emergency service. If you have chest pain, collapse, or severe breathlessness, call 999 straight away. If you have worrying symptoms that are not an emergency, speak to your GP or call NHS 111.
Frequently asked questions
Do I need to be fit to have a stress ECG?
No. The treadmill starts at a slow walk and builds up gradually. You exercise only as far as you safely can, and how long you manage is itself useful information. If you cannot walk on a treadmill or cycle, your clinician may suggest a different type of stress test.
Is a stress ECG the same as an exercise tolerance test?
Yes. Stress ECG, exercise ECG, treadmill test and exercise tolerance test are different names for the same type of test.
Can I drive home afterwards?
Most people can go home and return to normal activities once their heart rate has settled and they have got their breath back. If you feel unwell, tell the team before you leave and do not drive until you feel well.
What is the difference between a stress ECG and a resting ECG?
A resting ECG records your heart for a few minutes while you lie still. A stress ECG records it while your heart works harder, which can show problems that only appear with exertion. Read more in our guide to which heart test you might need.
Should I stop my heart medicines before the test?
Only if your doctor tells you to. Some medicines affect the result, so your clinician will advise you on what to do before your appointment.
Booking a stress ECG with The Heart Clinic
Our Stress ECG (exercise treadmill test) is coming soon to our new Luton clinic and is not available to book yet. You can register your interest or contact us to be told when it launches. In the meantime, a resting 12-lead ECG and Holter monitoring are available now, with no GP referral needed and a written report usually within 24 working hours.