Electrocardiogram (ECG or EKG) and ECG Stress Test

The electrocardiogram is commonly used as a relatively simple way of diagnosing heart conditions.

The electrocardiogram (ECG or EKG) evaluates the heart's rhythm and electrical activity. An ECG stress test is an ECG that is recorded during exercise-typically on a treadmill.

The ECG (or EKG) is a noninvasive test, ordered by your physician that records the electrical impulses that travel through the heart. This electrical activity determines the heart's rate and rhythm.

The electrical waves recorded by the ECG can help your physician determine whether your heart is functioning normally or experiencing problems. The waves are registered by electrodes placed on the chest, arms and legs. Each electrode controls an ink needle that writes on a grid paper. The higher the intensity of the electric wave, the higher up the needle will move on the paper. The paper moves at a certain speed beneath the needle, resulting in an ink curve.


There is no special preparation involved. You should not apply lotions or oils to your chest prior to the procedure. There are typically no restrictions on food, liquid or medications prior to the test. The ECG takes about 15 minutes.

Prior to Procedure

  • You will:
    • Have a physical exam and be asked about your medical history
    • Have your chest shaved if you have a hairy chest
  • For a stress test, you should:
    • Allow two hours between your last meal and the stress test
    • Wear comfortable clothing and walking shoes



Description of the Procedure

When your heart beats, it creates electrical signals. The ECG detects these signals from the surface of your skin and records them on a piece of graph paper. You will not feel anything during the procedure.

You’ll be asked to lie quietly on your back, with your shirt off. Six to twelve small adhesive pads (no suction cups) with attached wires will be placed across your chest, arms and legs. The wires will connect to the ECG machine. Your heart rhythms will be recorded in a few minutes and the test is complete.

If you’re having an ECG Stress Test, your heart rhythm will be recorded while you exercise, usually on a treadmill. The speed and slope of the treadmill will be slowly increased as you walk. The test will continue until you have reached a certain heart rate, certain ECG changes occur, or you are too tired to continue, are short of breath, or have chest pain. This test typically lasts less then 30 minutes.


Depending on your condition and your doctor’s assessment, you may have to have more tests. If you have a heart condition or abnormal ECG, keep a recent copy of your ECG in your wallet, purse, or car.