What is a stress test?

A stress test, also known as an exercise test or treadmill test, is used by doctors to determine how well a patient's heart works during physical activity. When the heart pumps harder during exercise, the stress test can reveal problems, such as poor blood supply through the coronary arteries - these problems might not be apparent at other times.

The stress test is also useful when the doctor is advising patients on the best type of physical activity for them.

A stress test typically involves walking on a treadmill or riding a stationary bicycle while the patient's breathing, blood pressure and heart rhythm are monitored.

According to the American Heart Association, "The (stress) test can show if there's a lack of blood supply through the arteries that go to the heart (coronary arteries)".

Some patients may not be able to do the exercise involved in a normal stress test, examples may include people with arthritis or certain disabilities in their limbs. There is another test - the pharmacological (chemical) stress test - in which the doctor gives the patient a medicine to make the heart work harder, as it might during exercise.

Why do a stress test

The doctor may recommend a stress test to determine whether the patient:

• has arrhythmia - irregular heartbeat or abnormal heart rhythm. When the electrical impulses that coordinate heart rhythm are faulty, the heart may beat irregularly.


• has symptoms that are heart-related, such as difficulty breathing or chest pain


• is suitable for an exercise program, and if so, how hard he/she should exercise


• is suitable for a cardiac rehabilitation program, and if so, how hard he/she should exercise


• is responding to heart treatment


• needs other tests to detect narrowed arteries, such as a coronary angiogram

A study carried out at the Cleveland Clinic found that a stress test can identify obstructive sleep apnea patients most at risk of death.

What happens during a treadmill stress test?

During a stress test the doctor aims to determine the patient's heart rate, blood pressure, breathing, and how tired he/she feels under different levels of physical activity.

During a stress test, the patient also undergoes an electrocardiogram (ECG or EKG) test. This is a simple test that records the heart's electrical activity - it helps the doctor understand how well the heart is working. An ECG shows how fast the heart is beating, it analyzes heart rhythm, and measures the strength and timing of electrical signals as they pass through each part of the heart.

For the ECG test, wires with electrodes are hooked up to the patient's chest, arms, shoulders and legs. Toward the end the patient may have to breathe into a mouthpiece.