A stress test, also called an exercise stress test, shows how your heart works during physical activity. Because exercise makes your heart pump harder and faster, an exercise stress test can reveal problems with blood flow within your heart. A stress test usually involves walking on a treadmill or riding a stationary bike your heart rhythm, blood pressure and breathing are monitored. Or you'll receive a drug that mimics the effects of exercise. Your doctor may recommend a stress test if you have signs or symptoms of coronary artery disease or an irregular heart rhythm (arrhythmia). The test may also guide treatment decisions, measure the effectiveness of treatment or determine the severity if you've already been diagnosed with a heart condition.