Isometric Exercise Testing

In the past decade, a great deal of interest has been focused on the hemodynamic effects of isometric exercise, a form of exercise where the contracting muscles develop force without shortening. Although certain details remain to be clarified, the existing body of knowledge indicates that isometric exercise has pronounced positive chronotropic, inotropic, and pressor effects on the cardiovascular system, and the magnitude and nature of the hemodynamic response of the normal heart to isometric exercise are different from those observed in the presence of heart disease. These facts, and the ease with which graded isometric exercise can be performed by use of a small instrument (dynamometer) that is manually squeezed by the patient (isometric handgrip test), have led to further studies directed at three potentially rewarding clinical applications of the test. The first diagnostic use of the isometric exercise test is for the detection of latent left ventricular (LV) failure.