Blood flow and oxygen debt repayment in exercising skeletal muscle

Abstract

Blood flow and oxygen consumption of the hind limb of the dog were determined before and following short periods of femoral artery occlusions during rest and three levels of exercise. Flow debts were underpaid or barely repaid. Oxygen debts were entirely or partially repaid depending upon the level of muscle performance and the duration of the ischemic period. In resting muscle and during light exercise, both increased blood flow and oxygen extraction were involved in repayment of the oxygen debts while an increased blood flow was most important during medium and strong exercise. Since oxygen debts were often not repaid during strong exercise in the presence of a decreased arteriovenous oxygen difference (and often an oxygen utilization below control levels), oxygen extraction was the limiting factor. Significant excess repayments of oxygen debts occurred in resting muscle and for 30-sec ischemic periods during light and medium exercise. The similarity of these data, especially during medium and strong exercise of skeletal muscles, to the responses of the beating dog heart to ischemic periods is pointed out.