For the body to function properly, the heart needs to pump blood at a
sufficient rate to maintain an adequate and continuous supply of oxygen and
other nutrients to the brain and other vital organs. Cardiac output is the term
that describes the amount of blood your heart pumps each minute. Doctors think
about cardiac output in terms of the following equation:
Cardiac output = stroke volume × heart rate
Your stroke volume is the amount of blood your heart pumps each time
it beats, and your heart rate is the number of times your heart beats per
A healthy heart with a normal cardiac output pumps about 5 to 6
liters of blood every minute when a person is resting.
During exercise, your body may need three or four times your normal
cardiac output, because your muscles need more oxygen when you exert yourself.
During exercise, your heart typically beats faster so that more blood gets out
to your body. Your heart can also increase its stroke volume by pumping more
forcefully or increasing the amount of blood that fills the left ventricle
before it pumps. Generally speaking, your heart beats both faster and stronger
to increase cardiac output during exercise.
Sufficient cardiac output helps keep blood pressure at the
levels needed to supply oxygen-rich blood to your brain and other vital
Other Works ConsultedHoit BD, Walsh RA (2011). Normal physiology of the cardiovascular system. In V Fuster et al., eds., Hurst's The Heart, 13th ed., vol. 1, pp. 94–117. New York: McGraw-Hill.
April 26, 2012
Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology
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