What does an exercise stress test measure?

• A. The heart rate while walking on a treadmill to determine how well the heart pumps blood.
• B. The electrical activity of the heart at rest.
• C. The structure of heart valves using ultrasound.
• D. The flow of blood in the lungs.

Answer: (A)

An exercise stress test investigates how the heart performs when it has to work harder. By having you walk on a treadmill, the heart rate rises and the test watches how the heart pumps blood under increasing demand, along with blood pressure, symptoms, and any ECG changes. This helps identify whether the heart can sustain adequate blood flow during activity and if there are signs of ischemia or poor pumping under stress.

This is why the best choice focuses on the heart’s response to exercise and its pumping efficiency during increased workload. Other tests look at different things: a resting ECG checks electrical activity when you’re not stressed, ultrasound examines valve structure, and tests that assess blood flow in the lungs involve imaging beyond the effort-induced response the stress test evaluates.