Peripheral and Visceral Vascular Effects of Exercise in the Erect Position

¹ From the Department of Physical Medicine and Rehabilitation, Montefiore Hospital, New York City

In able-bodied young men, the effect of exercise upon the blood flow in forearm, hand, kidney and liver was studied in the erect and supine postures. Work load varied from 3500 to about 9000 kg-m in 15 minutes. The effect of a heavy protein meal in combination with exercise was also investigated. Blood flow in forearm and hand was estimated with venous occlusion plethysmography. Kidney flow was measured with PAH clearance method without catheterization. Liver flow was approximately obtained with Bromsulphalein infusion. Only with a work load of 4000 kg-m or more was there definite reduction in kidney flow, which occurred more readily in the erect posture. No significant decrease of blood flow below resting control level was found in other investigated vascular areas. O₂ consumption for pedaling exercises was the same in the two postures. In relation to total cardiac output during heavy exercise, reduction in kidney flow makes a relatively small contribution to circulatory homeostasis. These results were obtained on able-bodied young men under physiologic conditions of exercise and were distinctly different from those on ‘normal patients,’ with forced standing or on the tilt table or under the stress of catheterization with or without sedation.