During an exercise stress test, an electrocardiogram (EKG or ECG) is conducted while walking on a treadmill to measure the heart’s response to the stress of physical activity. Your blood pressure and heart rhythm are monitored during the test as well. The results can show if there is a lack of blood supply through the arteries that go to your heart and if you have cardiovascular disease. It can also be used to determine your cardiovascular fitness, and the safety of an exercise program.