What is an exercise electrocardiogram (ECG)?

An electrocardiogram (ECG or EKG) is one of the simplest and fastest procedures used to evaluate the heart. Electrodes (small, plastic patches) are placed at certain locations on the chest, arms, and legs. When the electrodes are connected to an ECG machine by lead wires, the electrical activity of the heart is measured, interpreted, and printed out for the physician's information and further interpretation.

An exercise ECG is performed to assess the heart's response to stress or exercise. The ECG is monitored while a person is exercising on a treadmill or stationary bike. While this procedure is seldom used for young children, it may be very useful in evaluating adolescents and young adults.

An ECG tracing will be taken at certain points during the test in order to compare the effects of increasing stress on the heart. Periodically, the incline and treadmill speed will be increased in order to make exercise more difficult for the person being tested. If the person is riding a bicycle, he/she will pedal faster against increased resistance. In either circumstance, the person will exercise until reaching a target heart rate (determined by the physician based on age and physical status) or until unable to continue due to fatigue, shortness of breath, chest pain, or other symptoms.

An exercise electrocardiogram (EKG or ECG) is a test that checks for changes in your heart while you exercise. Sometimes EKG abnormalities can be seen only during exercise or while symptoms are present. This test is sometimes called a "stress test" or a "treadmill test." During an exercise EKG, you may either walk on a motor-driven treadmill or pedal a stationary bicycle.

The heart is a muscular pump made up of four chambers. The two upper chambers are called atria, and the two lower chambers are called ventricles. A natural electrical system causes the heart muscle to contract and pump blood through the heart to the lungs and the rest of the body.

An exercise EKG translates the heart's electrical activity into line tracings on paper. The spikes and dips in the line tracings are called waves. See a picture of the EKG components and intervals.

A resting EKG is always done before an exercise EKG test, and results of the resting EKG are compared to the results of the exercise EKG. A resting EKG may also show a heart problem that would make an exercise EKG unsafe.