Exercise stress testing is used to evaluate how well your heart copes with the extra demands placed on it during exercise. Patients with coronary artery blockages may have minimal symptoms and an unremarkable or unchanged ECG while at rest.

However, symptoms and signs of heart disease may become unmasked by exposing the heart to the stress of exercise. Exercise test can be used by your doctor to unmask underlying narrowed coronary artery, some form of exercise rhythm disturbances, heart rate response to exercise, your exercise tolerance.

It can also be used to assess your fitness following a heart attack.

How is an Exercise Test Performed?

A routine ECG is done when the heart is at rest. A technician performs the testing, and a doctor is also present. It usually takes between 30 and 60 minutes. You can eat and drink as normal before the test, but avoid a heavy meal beforehand, and wear loose clothing and comfortable walking shoes.

You will be asked to walk on a treadmill. The speed and gradient are increased every 2–3 minutes, depending on the reason for the test. You need to push yourself as hard as you can, to achieve a result that shows your true capabilities.

During the test your symptoms, blood pressure, heart rate, rhythm, ECG and exercise ability will be monitored. Underlying narrowed artery can produce characteristic abnormalities in your ECG. If you experience chest pain, undue breathlessness, fatigue or significant changes in blood pressure, heart rate or ECG, the test will be stopped.

What is the Reliability of a Regular Stress Test?

If a patient is able to achieve the target heart rate, a regular treadmill stress test is capable of diagnosing important disease in approximately 67% or 2/3 rd of patients with coronary artery disease.

The accuracy is lower (about 50%) when patients have narrowing in a single coronary artery or higher (greater than 80%) when all three major arteries are involved. Approximately 10% of patients may have a "false-positive" test (when the result is falsely abnormal in a patient without coronary artery disease).