Section 4: Cardiac Output Calculation

When at rest, the typical heart rate is about 70 beats per minute and at each contraction the left ventricle ejects about 70 ml – a measurement termed the stroke volume. We can calculate the cardiac output (that is the volume that the heart pumps each minute) by multiplying the two figures. The result is approximately 5 litres per minute. When we engage in activity the exercising muscles require an increased amount of oxygen and the response of the body is to increase cardiac output by raising both pulse rate and stroke volume.