What Is a Stress Test?
Published on April 11, 2025
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Stress tests are common medical procedures that can reveal how well your heart functions when it's working hard to pump blood through your body. They can be used to determine your cardiovascular fitness, help find the underlying cause for your heart-related symptoms, or diagnose heart disease.
Healthcare providers may recommend these tests as preventive measures, particularly if you have a family history of heart disease or heart attacks or if you have a health condition that increases your risk of heart disease, such as diabetes, high blood pressure, or high cholesterol.
Types of Stress Tests
Each type of stress test uses a different method to make your heart work harder. You may be required to exercise on a stationary bike or treadmill or take medication to simulate exercise and show how well your heart functions when it's pumping hard.
Exercise Stress Test
Exercise stress tests, sometimes called cardiopulmonary exercise testing, are often used to determine your cardiovascular fitness and detect whether you have any heart-related issues that may affect your physical activity.
During this test, you will exercise on a treadmill or a stationary bike, and the level of difficulty will get progressively harder during the session. A healthcare provider will monitor your blood pressure and connect you to an electrocardiogram (ECG) machine, which tracks your heartbeat and the electrical pulses in the heart.
While this test is generally considered safe, it's not recommended if you've recently had a heart attack, have persistent chest pain, or have inflammation of the heart muscle, such as myocarditis and pericarditis. There is generally minimal preparation for this type of test, though your doctor may recommend avoiding caffeine or other stimulants that can increase your heart rate.
Stress Echocardiogram
A stress echocardiogram is similar to an exercise stress test. However, a healthcare provider will use ultrasound to create a moving cross-sectional view of your beating heart before and after exertion, whether through exercise or medication. This will allow the provider to see the heart's chambers and valves.
If you're unable to exercise during this test, a provider may give you a medication called dobutamine to cause your heart to beat faster and harder.
Nuclear Stress Test
During a nuclear stress test, a healthcare provider will inject a tracer with a radioactive substance into a vein in your arm before you begin exercising. If you're unable to exercise, they'll use a vasodilator, which widens the arteries, or give you dobutamine to mimic physical exertion.
A special camera can track the radioactive substance, typically thallium or sestamibi, showing doctors how well blood flows in and out of the heart muscle both at rest and when stressed. If the substance doesn't appear in certain parts of the heart in the image, those areas are likely not receiving enough blood.
While a nuclear stress test can determine your cardiovascular fitness, it's also used to see if previous treatments, such as stents, have been effective and to diagnose heart disease in place of more invasive tests, like cardiac catheterization.
Cardiac MRI Stress Test
A cardiac MRI stress test doesn't require running on a treadmill or using a stationary bike. Instead, it uses MRI scans in combination with drugs that simulate exercise to understand how the heart functions under stress. An MRI scan is a noninvasive test that uses radio waves and magnets to take clear, detailed images of the inside of your body; in this case, your heart and blood vessels.
If you have a pacemaker or other metal in your body, such as screws, it's important to tell your provider before scheduling this test.
This test is relatively new and is used less frequently than other stress tests.
Why Is a Stress Test Done?
Stress tests are done for a number of reasons related to heart health. You may undergo an exercise stress test to assess your cardiovascular fitness, fine-tune your exercise regimen, monitor treatment for a heart condition, or detect heart issues that may affect your physical activity.
They're also commonly used to detect coronary artery disease, and they can see how well blood is flowing in and out of the heart muscle.
If you have a congenital heart or valvular disease, you may undergo a stress test before becoming pregnant to determine if your pregnancy may be considered high risk.
In short, stress tests can be used to diagnose or determine:
- Coronary artery disease (CAD) or worsening CAD
- Obstructive coronary artery disease
- Cardiovascular fitness
- If you're a candidate for any kind of surgery
How Is a Stress Test Performed?
Stress tests are typically done in an outpatient setting and are noninvasive. In some cases, such as a cardiac MRI stress test or nuclear stress test, you may need to do the test at a specialized cardiac or pulmonary testing center.
The length of the test depends on the type you're undergoing. Exercise stress tests typically take one hour, which includes preparation, exercise, and recovery. Tests that involve imaging, such as a cardiac MRI, stress echocardiogram, or nuclear stress test, take more time, up to three hours.
Depending on the test, you'll exercise on a treadmill or stationary bike for a short time, usually 10 to 15 minutes. If you're not doing an exercise test, you'll be given medication or administered medication through an IV, which will dilate your coronary arteries or increase how hard your heart beats.
How Do I Prepare for a Stress Test?
It's important to talk with your healthcare provider at least a few days before your test to determine how to prepare.
Be sure to inform them of any over-the-counter or prescription medications you're taking. They may advise you to avoid certain medications, such as beta-blockers, asthma inhalers, and any caffeine-containing pain medications. You may be asked to avoid any foods or drinks with caffeine, such as tea, coffee, soda, and chocolate, 24 hours beforehand. Caffeine is a stimulant and can increase your heart rate. In some cases, you may need to avoid eating or drinking altogether hours before your test. If you smoke, you'll need to stop beforehand.
If you'll be exercising during the test, make sure to wear supportive, comfortable running or workout shoes. You'll also want to wear a two-piece outfit, such as loose, comfortable pants and a shirt, so that it's easy to attach any electrodes to your chest.
What Should I Expect During a Stress Test?
For an exercise stress test or stress echocardiogram, a healthcare provider will hook you up to an ECG by placing sticky electrodes on your chest, arms, and legs.
Before the test begins, they will take photos of your heart, take blood pressure readings, and review your ECG results, to see how your heart behaves when it isn't under stress.
For the test, you'll then be asked to work out on a treadmill or exercise bike for around 10 to 15 minutes. The speed or level of difficulty will gradually increase during that time. Including preparation and recovery, the test will take about one hour. During the test, you'll be asked to tell the provider when you've reached maximum exertion and you cannot exercise any more.
If you're undergoing a nuclear stress test, a healthcare provider will inject a radiotracer with a radioactive substance into your arm. They'll then ask you to lie down and wait between 15 and 45 minutes while the tracer circulates throughout your body. The provider will then use a special camera to scan and take pictures of your heart while you're at rest.
If you're exercising during this test, the provider will then increase your level of difficulty. If you're receiving medication instead, they'll give it to you at this point. The provider will measure your blood pressure and heart activity throughout the test.
Once they determine that your heart is working hard, they'll inject the tracer with the radioactive substance again and wait another 15 to 45 minutes before taking pictures of your heart at maximum effort. The imaging will show how much blood is in the different parts of your heart when it's working hard.
With a cardiac MRI stress test, you'll lie down face-up on a bed connected to the MRI machine. During the test, the bed will move through the machine and take photos of your heart and blood vessels. A radiographer will operate the machine from a separate room, but they'll be able to communicate with you through an intercom system. This test is considered painless, though you may experience some shortness of breath from the medication and warmth from the machine. If you're not used to or dislike enclosed spaces, you may also feel anxious.
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What Are the Potential Risks Associated With a Stress Test?
Risks associated with stress tests are low.
To prevent potential complications, a healthcare provider will recommend a medication-induced stress test over an exercise stress if you have:
- Unstable angina
- A history of heart failure
- Recently experienced a heart attack
- Acute pulmonary embolism
- Low blood oxygen levels
- Inflammation of the heart lining
What Type of Care Is Needed Following a Stress Test?
Following a stress test, you'll usually be monitored for about 15 minutes, or however long it takes for your heart rate to return to normal. You should be able to resume your normal activities afterward.
Make sure to drink plenty of water after the test, especially if you've had a nuclear stress test, so that your body flushes the radiotracer. Your healthcare provider will advise you when you can begin taking your usual medications and anything else you may need to consider following the test.
What Are the Possible Complications and Side Effects of a Stress Test?
Depending on your exercise tolerance, you may have shortness of breath, muscle cramps, or fatigue while using the treadmill or stationary bike. You may also experience skin irritation where the ECG electrodes attach to your body.
During medication-induced stress tests, you may experience a stinging sensation at the injection site, headache, or nausea. An allergic reaction to the radioactive substance used in a nuclear stress test is also possible, though this is a rare complication.
Much less common symptoms during and after a stress test include the following:
- Chest pain or discomfort, which is caused by reduced blood flow to the heart
- Abnormal heart rhythms, or arrhythmias
- Bronchospasm, or narrowing of the bronchial tubes in the lungs
If you experience any of these symptoms, you'll want to inform your healthcare provider immediately. These are serious side effects and are more common in people with underlying heart disease, particularly those with heart failure.
Life-threatening complications, such as a heart attack, ventricular tachycardia, and cardiac rupture, are extremely rare, occurring in about 1 in every 6,500 people.
What's Next
Following your stress test, your healthcare provider will discuss the results with you and come up with a treatment plan or schedule additional tests if required.
If you receive normal results, this likely means your heart is functioning as it should. Abnormal results may indicate scarring from a previous heart attack or show reduced blood flow to the heart, which may be a sign of a blockage. False-positive tests are possible. If you receive abnormal results, your provider may order another type of stress test, such as a stress echocardiogram or nuclear stress test, depending on your previous one. They may also suggest cardiac catheterization or a CT coronary angiogram, which uses X-ray imaging to look at your blood vessels and diagnose heart disease.
From there, they will work with you to determine a treatment plan. If the tests reveal mild heart disease, they may recommend lifestyle changes, which can include changing your diet, losing weight, stopping smoking, or trying other heart medications.
The Takeaway
- Stress tests are used to detect or monitor heart disease or other heart-related issues, or to assess a person's cardiovascular fitness.
- During a stress test you'll exercise or use a medication that causes your heart to beat faster and more forcefully, allowing a doctor to evaluate how your heart performs under stress.
- The tests are safe and noninvasive, and complications rarely occur. People with existing heart disease may need to perform the test in a hospital, rather than a medical office, where they can get immediate care if needed.
- Stress tests only take a few hours or less, and don't require much special preparation or recovery.
Resources We Trust
- Mayo Clinic: Nuclear Stress Test
- Harvard Health Publishing: Cardiac Exercise Testing: What It Can and Cannot Tell You
- American Heart Association: Lifestyle Changes to Prevent a Heart Attack
- National Heart, Lung, and Blood Institute: What Is Heart-Healthy Living?
- Johns Hopkins Medicine: Diagnosis and Screening for Cardiovascular Conditions
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
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Meet Our Experts
Chung Yoon, MD
Medical Reviewer
Chung Yoon, MD, is a noninvasive cardiologist with a passion for diagnosis, prevention, intervention, and treatment of a wide range of heart and cardiovascular disorders. He enjoys clinical decision-making and providing patient care in both hospital and outpatient settings. He excels at analytical and decision-making skills and building connection and trust with patients and their families.
Kaitlin Sullivan
Author
Kaitlin Sullivan reports on health, science, and the environment from Colorado. She has a master's in health and science journalism from the City University of New York.