Health Information

Stress tests, or graded exercise tests, are conducted primarily to aid in diagnosing or quantifying heart or lung disease and to evaluate the functional capacity asymptomatic individuals. The tests are usually given on motorized treadmills or bicycle ergometers (stationary, variable-resistance bicycles). Workload intensity (how hard the subject is working) is adjusted by progressively increasing the speed and the incline of the treadmill or by progressively increasing the pedaling frequency and resistance on the bicycle. The test starts at a low intensity and continues until a prespecified workload is achieved, physiologic symptoms occur, or the subject is too fatigued to continue.

During the diagnostic testing, the patient is monitored with an ECG, and blood pressure is taken each minute. A test is considered positive if ECG abnormalities occur (such as ST segment depression, inverted T waves, or dangerous arrhythmias) or if physical symptoms such as chest pain develop. A test that is interpreted as positive in a person who does not have heart disease is called a false positive test. In men, false positives occur only about 10% to 20% of the time, so the diagnostic stress test for men has a specificity of 80% to 90% women have a greater frequency of false positive tests, with a corresponding lower specificity of about 70%.

The sensitivity of a test means that people with disease are correctly identified and there are few false negatives. The sensitivity of the stress test is reported to be 60% to 80%; that is, if 100 people with heart disease were tested, 60 to 80 would be correctly identified, but 20 to 40 would have a false negative test. Although stress testing is now on important diagnostic tool, it is just one of several tests and used to determine the presence of coronary artery disease.

Stress tests are also conducted on people not suspected of having heart or lung disease to determine their present functional tests are administered in the same way as diagnostic tests, but they are conducted by exercise physiologists and a are conducted by exercise physiologists and a physician need not be present. These tests are used to establish safe exercise prescriptions, to aid athletes in establishing optimal training programs and as research tools to evaluate the effectiveness of a particular training regimen. Functional stress testing is becoming more prevalent as more people are joining hospital – or community – based wellness programs for disease prevention.