What is a Stress Test?
A stress test, also called an exercise stress test or treadmill test, evaluates how well your heart works during physical activity. When you exercise, your heart has to pump more blood and work harder than when you're at rest. A stress test can reveal problems with blood flow within your heart that might not be noticeable when you're resting.
During the test, you'll exercise (typically walking on a treadmill or pedaling a stationary bike) while your heart rate, blood pressure, breathing, and how tired you feel are monitored. This helps doctors diagnose heart problems, determine safe exercise levels, and assess the effectiveness of heart treatments.
Types of Stress Tests
Several types of stress tests are available, depending on your health condition and what information your doctor needs:
Common Types
- Standard Exercise Stress Test: Monitors heart rate, blood pressure, and EKG while you exercise
- Stress Echocardiogram: Uses ultrasound images of your heart before and after exercise to assess heart muscle function and blood flow
- Nuclear Stress Test: Uses a small amount of radioactive substance to create detailed images showing blood flow to the heart
- Pharmacological (Chemical) Stress Test: Uses medications to simulate exercise effects for people who can't exercise adequately
Why You Might Need This Test
Your doctor may recommend a stress test for several reasons:
- To diagnose coronary artery disease or determine its severity
- To investigate symptoms like chest pain, shortness of breath, or heart palpitations
- To determine a safe level of exercise for cardiac rehabilitation or fitness programs
- To evaluate the effectiveness of heart treatments or medications
- To check heart health before surgery
- To assess heart rhythm problems (arrhythmias) that occur with exercise
- To guide treatment decisions for people with known heart disease
- As part of a routine health evaluation for people at high risk for heart disease
Preparing for Your Stress Test
Proper preparation helps ensure accurate results and your safety during the test. Your healthcare team will provide specific instructions, which typically include:
- Don't eat or drink anything except water for 3-4 hours before the test
- Avoid caffeine for at least 24 hours before (no coffee, tea, soda, chocolate, or caffeine medications)
- Ask about medications: Your doctor may ask you to skip certain heart medications before the test
- Wear comfortable clothes suitable for exercise, including athletic shoes
- Continue taking diabetes medications unless told otherwise, but coordinate timing with food restrictions
- Tell your doctor if you have any joint problems that might limit your ability to exercise
- Inform your doctor if you use an inhaler for asthma—you may need to bring it
What to Expect During the Test
Understanding the process can help you feel more comfortable and prepared:
The Procedure
- Duration: The entire process typically takes 45-60 minutes, though the actual exercise portion is usually 7-12 minutes
- Preparation: Sticky electrode patches are placed on your chest to record your heart's electrical activity (EKG)
- Blood pressure cuff: Placed on your arm to monitor blood pressure throughout the test
- Resting measurements: Initial readings are taken while you're at rest
- Exercise phase: You'll start walking on a treadmill or pedaling a bike at a slow, easy pace
- Progressive intensity: The speed and incline (or resistance) gradually increase every few minutes
- Monitoring: Healthcare staff continuously monitor your heart rate, rhythm, blood pressure, and how you're feeling
- Stop conditions: The test continues until you reach your target heart rate, develop symptoms, or can't continue
- Cool down: After peak exercise, you'll walk slowly or sit down while being monitored
- Recovery monitoring: You'll be watched for 10-15 minutes after exercise or until your heart rate returns near baseline
During the Test: What to Tell Your Doctor
It's crucial to communicate with your healthcare team during the test. Immediately tell them if you experience:
- Chest pain or discomfort
- Arm, jaw, or neck pain
- Severe shortness of breath
- Dizziness or lightheadedness
- Unusual fatigue
- Leg cramps or pain
- Nausea
- Irregular heartbeat or palpitations
- Any other unusual symptoms
After the Test
After your stress test, you can typically resume normal activities immediately. Some people feel tired for a few hours afterward. If you had a nuclear stress test, you might need to avoid close contact with pregnant women and young children for a few hours due to the radioactive tracer.
Your doctor will discuss the results with you, either immediately after the test or at a follow-up appointment. The results will help guide decisions about your heart health care.
Understanding Your Results
Stress test results are considered along with your symptoms, medical history, and other test results. Your doctor will look at:
- How long you were able to exercise
- How your heart rate and blood pressure responded to exercise
- Any irregular heart rhythms that developed
- Changes in your EKG that might indicate reduced blood flow to the heart
- Any symptoms you experienced during the test
- How quickly your heart rate returned to normal after exercise
What Results Mean
A normal stress test suggests that your heart receives adequate blood flow during exercise. An abnormal result doesn't always mean you have heart disease—additional tests may be needed for a definitive diagnosis. Your doctor will explain what the results mean for you and recommend next steps, which might include lifestyle changes, medications, or additional testing.
Risks and Safety
Stress tests are generally very safe. Serious complications are rare because you're closely monitored throughout the test. However, there are small risks:
- Low blood pressure or dizziness
- Chest pain or discomfort
- Irregular heart rhythms (arrhythmias)
- Very rarely, heart attack (about 1 in 10,000 tests)
Safety Measures
The test is performed in a supervised setting with emergency equipment readily available. The healthcare team is trained to handle any complications that might arise.