Beta‐Adrenergic Blockade and Central Circulation during Exercise in Sitting Position in Healthy Subjects

The effect of a beta‐adrenergic blockade on central circulation during exercise in a sitting position has been examined in 8 healthy young men. After oral administration of propranolol in doses of about 0.22 mg/kg b.wt. there were significant decreases in pulse rate, cardiac output and mean pressure in the brachial artery during exercise. An increase of a‐v oxygen difference and of mean pressure in the pulmonary artery was noted. No systematic change was noted in oxygen uptake and stroke volume respectively during the beta‐blockade. The physical working capacity at pulse 170 increased on an average by 15 % after propranolol. This increase was made possible primarily through a better peripheral oxygen utilization and could only be explained to a minor extent by an increase in stroke volume.