An exercise tolerance test, also known as a stress test, involves walking on a motorized treadmill to raise the heartís workload. This shows any inadequacies in blood flow to the heart that are not apparent on a resting electrocardiogram. A stress test may also explain any symptoms that you have reported to your physician. The test takes one hour to perform, and you should try to get a full nightís sleep before the test. Wear (or bring) comfortable clothes and walking shoes. Eat a light meal before the test (do not fast!) and take your medications as usual, unless otherwise directed by your physician. Be sure to drink sufficient water before the test so that you will be well hydrated. A shower and towels are available if you will need to shower after the exercise.