Cardiac Output. Cardiac output is the amount of blood your heart pumps out in one minute. It is regulated by the amount of blood your heart pumps out in one contraction, or stroke volume, and the number of times your heart beats in one minute, or your heart rate.Cardiac output increases as a short-term and a long-term effect of regular aerobic exercise.Initially, cardiac output increases due to an increase in your heart rate. Then, as your aerobic fitness improves, cardiac output increases due to an increase in stroke volume and a decrease in heart rate.ardiac output increases as a short-term and a long-term effect of regular aerobic exercise. Initially, cardiac output increases due to an increase in your heart rate.