Hemodynamic effects of isometric exercise in normotensive and hypertensive subjects.

Isometric exercise increases arterial pressure and heart rate in normotensive individuals and also in patients with labile and fixed essential hypertension. The hypertensinogenic effect of isometric exercise is mediated through an increase in cardiac output because the peripheral vascular resistance is usually not affected. The cardioaccelerating effects of isometric exercise are mediated through an initial vagal withdrawal and a later stimulation of the sympathetic system. However hypertensive patients with defective sympathetic adjustments are not immune to the hypertensinogenic and cardioaccelerating effects of isometric exercise. Since isometric exercises are performed several times during daily activities, they may result in dangerous elevations in arterial pressure in patients with already increased arterial pressure, and this may eventually lead to cerebrovascular accidents and/or cardiac decompensation. It is therefore recommended that patients with elevated arterial pressure, or persons prone to hypertension, should refrain from such activities.