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How does an Exercise Stress Test work?

How your heart performs under stress is an important indicator of its health, and an exercise stress test is one way for your doctor to determine how well your heart functions.

As your body works harder, during exercise for example, it requires more oxygen which causes the heart to pump more blood and your heart rate and blood pressure to increase. During an exercise stress test, sometimes called a treadmill test, your electrocardiogram (ECG), heart rate and blood pressure are monitored as you walk on a treadmill. By monitoring and recording these changes this test can indicate if parts of the heart have inadequate blood supply, which could indicate the presence of coronary artery disease. It can also evaluate your current fitness level.

There are two main types of stress testing performed at Mayfair Diagnostics. An exercise stress test and myocardial perfusion imaging (MPI) An MPI is an exercise stress test that involves an injection of a radioactive isotope that is taken up by the heart muscle. The radioactive material (radiopharmaceutical) is injected intravenously at rest and at stress (during exercise) and imaged with a gamma camera. For more information about this exam, read this article.


Please note that you will need to stop certain medications 48 hours before your exam, avoid caffeine 24 hours before your exam, and not drink or smoke for four hours before your exam. You will also need to wear comfortable clothes.

During an exercise stress test, a technologist and an internal medicine physician will be monitoring you. To begin, the physician will discuss your medical history and symptoms with you. Then, the technologist will place 10 electrodes (adhesive patches) on your chest which are attached to the ECG which charts your heart’s electrical activity during the test. The sites where the electrodes are placed will be cleaned with alcohol and shaved if necessary. A mild abrasion may also be used to ensure a good quality ECG recording.

Before you start exercising, the technologist will perform a resting ECG, measure your resting heart rate, and take your blood pressure. You will then be asked to begin walking slowly in place on the treadmill. The speed and incline of the treadmill is gradually increased throughout 5 to 15 minutes of exercise. The majority of the test occurs at a walking pace, with some ending up jogging.

At regular intervals, the technologist will ask you how you are feeling, particularly if you feel chest, arm, or jaw pain or discomfort, shortness of breath, dizzy, lightheaded, or if you have any other unusual symptoms. We will stop the test if you become too tired, experience chest pain, or when we have gathered enough information.

After the exercise portion is over, you will need to sit and relax. We will continue to monitor your ECG, heart rate, and blood pressure as they return to normal. You are then free to leave.


An exercise stress test will examine how well your heart responds to the stress of different levels of exercise. It is often ordered to help determine your baseline, as part of a general work up if you have atypical chest pain combined with high cholesterol and high blood pressure. It can also help gauge your fitness level or whether it’s safe to begin an exercise program.

An MPI, on the other hand, is often ordered to further investigate an abnormal resting ECG or exercise stress testing. It can also be recommended if you have a family history of heart disease, diabetes, previous angioplasty, stent, or heart attack.


Your results will be reviewed by the internal medicine physician and your health care practitioner will receive a comprehensive report within a few days of your exam. Your doctor will then be able to review your results with you, along with the results of any other test you may have undergone, and determine the next steps in your health care treatment plan.


Exercise stress tests are generally safe for most people. To determine whether this exam is appropriate for you, you will need to discuss your symptoms and medical history with your health care practitioner, who would then provide you with a requisition for this procedure if recommended. Your requisition, and any lab work and resting ECG, are sent to Mayfair for triaging. Our contact centre will then be in touch to coordinate booking and explain how to prepare for your exam.

Please visit the exercise stress test page, for more information about what happens during this exam and how to prepare.


American Heart Association (2018) “Exercise Stress Test.” Accessed January 16, 2019.

Harvard Medical School (2018) “Cardiac exercise stress testing: What it can and cannot tell you.” Harvard Men’s Health Watch, Harvard Health Publishing. Accessed January 16, 2019.

University of Ottawa Heart Institute (2018) “Treadmill Exercise Stress Test.” Accessed January 16, 2019.

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