In isometric exercise, all are increased except

In normal individuals the increase in blood pressure is mediated by a rise in cardiac output with little or no change in systemic vascular resistance. With the sta of an isometric muscle contraction, the hea rate rises, probably as a result of psychic stimuli acting on the medulla oblongata. The increase is largely due to decreased vagal tone, although increased discharge of the cardiac sympathetic nerves plays some roleStroke volume remains almost the same, but given that hea rate increases cardiac output increases(CO/P=stroke volume*hea rate)Within a few seconds of the onset of an isometric muscle contraction, systolic and diastolic blood pressures rise sharply which increase Mean Aerial PressureRef: Ganong's Review of Medical Physiology Twenty-Third Edition Page No: 518