A cardiac stress test (also called a treadmill test or exercise testing) is a diagnostic test that evaluates how well your heart works when it has to work harder than usual. During the test, you walk on a treadmill (or sometimes pedal a stationary bike) while your healthcare team monitors your heart’s electrical activity with an electrocardiogram (ECG/EKG), along with your heart rate, blood pressure, and symptoms.

The goal is to see whether physical exertion triggers signs that the heart muscle is not getting enough oxygen-rich blood. As the treadmill speed and incline gradually increase, the heart must pump faster and harder. This can reveal problems that may not show up when you are resting.

Results are interpreted using several pieces of information, including your ability to exercise, your heart rate and blood pressure response, any symptoms (such as chest pain, shortness of breath, dizziness, or unusual fatigue), and ECG/EKG changes that can suggest reduced blood flow to the heart (ischemia). In general:

Normal/negative findings often mean you reached an expected exercise level for your age and fitness without concerning symptoms or ECG changes, which lowers the likelihood of significant coronary blockage (though it does not eliminate risk entirely).

Abnormal/positive findings may suggest reduced blood flow to part of the heart, an exercise-induced rhythm problem, or an abnormal blood pressure response. If results are abnormal—or if the test is limited because you could not exercise enough—your clinician may recommend additional testing (such as a stress echocardiogram, nuclear stress test, coronary CT angiography, or other cardiac evaluation).

A treadmill stress test is commonly ordered to evaluate symptoms, check for cardiovascular disease, and guide safe activity levels. It is especially helpful when symptoms happen with exertion and improve with rest.

Your clinician may recommend a cardiac stress test if you have:

Symptoms that could be heart-related, such as exertional chest pain or pressure (possible angina), shortness of breath, lightheadedness, palpitations, or unexplained fatigue.

Risk factors for coronary artery disease, particularly if you have symptoms or an abnormal baseline ECG/EKG. Risk factors include high blood pressure, high cholesterol, diabetes, smoking history, obesity, sedentary lifestyle, chronic kidney disease, or a strong family history of early heart disease.

Known heart disease, to understand functional capacity, determine if treatment is working, or help decide next steps (medication changes, further imaging, or procedures).

After a heart event or procedure (as directed by your cardiologist), such as after a heart attack, stent placement, bypass surgery, or during cardiac rehabilitation—to evaluate exercise tolerance and create a safe exercise plan.

Evaluation of exercise capacity for work clearance, sports participation, or preoperative risk assessment in selected patients (this depends on your health status, planned surgery, and overall risk).

Because this is an exercise testing procedure, it’s most appropriate for people who can walk safely on a treadmill. If you cannot exercise adequately due to joint pain, mobility limitations, or certain medical conditions, your clinician may recommend a pharmacologic (medication-based) stress test instead.

• Coronary artery disease (CAD)
• Stable angina (exercise-related chest pain)
• Myocardial ischemia (reduced blood flow to the heart muscle)
• Previous myocardial infarction (prior heart attack) and follow-up assessment
• Heart rhythm disorders (exercise-induced arrhythmias, such as atrial fibrillation or ventricular ectopy)
• Heart failure (functional capacity assessment in selected patients)
• Hypertension (including abnormal blood pressure response to exercise)
• Valvular heart disease (e.g., aortic stenosis evaluation in appropriate patients)

• Assessing overall heart health and estimating exercise capacity (fitness level)
• Evaluating exertional symptoms such as chest pain, shortness of breath, or fatigue
• Screening for possible cardiovascular disease in symptomatic or higher-risk individuals
• Guiding safe return to exercise after a cardiac event or procedure
• Monitoring response to treatment for angina or coronary artery disease (medications and lifestyle changes)
• Helping set personalized exercise targets using measured heart rate response and tolerance
• Supporting preventive cardiology goals such as improving endurance and reducing cardiac risk under medical guidance