There are two Electrocardiographic tests they can do on the heart to check for injury (heart attack). An electrocardiograph checks your heart out by monitoring you with electrodes attached to a machine which draws the electrical activity in your heart. One test involves you resting (laying down) and the other test, called a Stress Test, involves you running and being active while the electrodes monitor your heart.
Sometimes the stress test is the only way doctor's can evaluate you for heart injury. Other times your family doctor may want higher risk individuals to have a stress test so you have a documented Electrocardiograph to compare with just in case of emergency.