Clinical exercise tests are used primarily for diagnosis of coronary insufficiency or appraisal of working capacity. Occasionally hemodynamic responses are observed during diagnostic catherization of the heart. Since interpretation of findings depends upon quantitative differences from normal values, variations due to age, sex, physical status and circumstances of the test need to be appreciated. To be effective, exercise stresses must involve large muscle masses, and the patient or subject must be ambulatory, cooperative and properly motivated. Some of the approaches to testing will be reviewed, and preliminary observations on a new technique will be presented.The simplest test of exercise tolerance is for a physician to accompany a cardiac patient over one or more flights of stairs and to observe the symptoms. If this is not rewarding, increasing the work load by accelerating the pace or taking two steps at a time is more likely to be informative. But under these conditions the work loads are not well standardized, physiological responses are not usually monitored, and the physician is not necessarily of the same sex and comparable age.Master's two step test is familiar to most internists; its value for diagnosis and prognosis of coronary insufficiency has been established. 1,2 An abnormal resting electro-cardiogram is considered a contraindication for performance of this test. Although interpretation of results depends upon electrocardiographic changes, these have not been monitored routinely during exertion, even though a suitable technique was described 10 years ago. 3 The exercise stress varies with age, sex and body weight, but in terms of energy expenditure per unit of weight the underweight individual is stressed much more than the overweight person.
1. Several approaches to assessment of physical work capacity in the upright posture in normal adults and cardiac patients have been reviewed critically.
2. Preliminary experience has been presented with a new multistage treadmill test of maximal exercise which permits appraisal of either a physically trained normal subject or an impaired but ambulatory cardiac patient.
3. The most effective means of differentiating cardiacs from normals has been an estimate of the total oxygen intake/Kg of body weight.
4. The need for monitoring the circulation with respect to arrhythmias, ischemia and/or hypotension has been emphasized.
The authors wish to acknowledge their appreciation of many physicians, particularly Dr. Robert M. Levenson of the Seattle Cardiac Work Evaluation Clinic, and medical and graduate students who have assisted in the testing of patients and normals. The assistance of Mrs. Gladys Pettet is gratefully acknowledged also.
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