[Functional state of the left regions of the heart in healthy persons during isometric exercise]

Hemodynamic parameters of left and atrial contractile and pump functions were examined in 25 healthy males undergoing leg isometric exercise, by employing echocardiography. Analysis of changes in intracardiac hemodynamics showed that for provision of a marked pressor reaction occurring in healthy persons during isometric exercise, there was enhanced left ventricular myocardial contractility and thereby higher stroke and minute volumes. To maintain the required increase in stroke volume at the maximal exercise level, an accessory mechanism of compensation gears (by the Frank-Starling type), which operates due to myocardial diastolic relaxation, elevated venous blood supply at the expense of sucking cardiac action, and augmented left atrial contractility.