Cardiac output - is the product of the heart rate, which is the number of beats per minute, and the stroke volume, which is amount pumped per beat. The cardiac output is usually expressed in liters/minute. For someone weighing about 70 kg , the cardiac output at rest is about 5 liters/minute. For a typical, fit young person doing exercise , the cardiac output might go up to about 20 liters/min at the peak of exercise. The formula for this is expressed as CO = SV x HR.