A maximal-graded exercise test, also referred to as a stress test or maximal GXT, tests how hard the heart works during exercise. It will help find the limits of the cardiovascular system. To identify any heart problems before the test, an ECG, or electrocardiogram, will be done while resting. Taking the blood pressure and heart rate at rest will form a baseline from which to start measuring. Tracking and recording everything continues for the duration of the test. Positioning sensors on the chest is required for the ECG, and they will remain during the entire test, constantly tracking the heart's activity. Constant observation of any changes in blood pressure or heart rate is imperative as well.
Maximal-Graded Exercise Tests on a Treadmill
Testing begins with the patient on a treadmill and starting to walk or jog at low intensity. The low intensity will put only a small amount of stress on the cardiovascular system. As the test continues, it will get progressively harder. Making the patient go faster or making the incline steeper will raise the intensity. The faster or steeper you go, the more stress on the cardiovascular system, thereby helping to find its limits.
Symptom-Limited Maximal GXT
"Two different types of graded exercise tests can be administered. The symptom-limited maximal GXT is the more common of the two," according to "Fitness: The Complete Guide" by Frederick C. Hatfield, Ph.D. During this test, the exercise intensity will continuously increase. Once the cardiovascular system starts showing signs of reaching its limit, the test ends and analyzing the information gathered begins to determine how hard the heart was working.
Sub-maximal GXT
This test begins in the same manner as the symptom-limited test. The sub-maximal graded exercise test will start out easy and get more difficult with the conclusion of this test coming in one of two ways. There will be a preset point to stop at, usually a specific heart rate, but if you reach your cardiovascular limit before you hit that heart rate, the test will stop.
Who Can Oversee a Maximal GXT?
Complete these tests only in a facility where the appropriate medical professionals are available and only by someone qualified to handle an emergency should it arise. As reported by Hatfield, "According to the guidelines established by the American Heart Association (AHA) and adopted by ISSA, all individuals who administer GXT's should be trained in cardiopulmonary resuscitation (CPR), and at least one of the technicians in the testing area should also be trained and certified in advanced cardiac life support. Also, in accordance with AHA guidelines, a physician should be on the premises (e.g., in the building) at all times."
References
- "Fitness: The Complete Guide"; Frederick C. Hatfield, Ph.D.; 2008
- American Heart Association: Cardiovascular Media Library - Exercise Stress Test
