It records the electric currents produced by the heart. It measures the current through the skin with electrodes that are attached to the chest.
Electrodes are harmless devices with wires that lead to a recording machine.
A resting EKG takes no more than 5 to 10 minutes to administer. An EKG taken during exercise, called a stress test, takes longer. The examiner attaches electrodes to the chest, wrists, and legs with a special gel. A recording machine will trace a wave pattern for each wire lead. For a resting EKG, the person must remain still and quiet.