Define cardiac reserve? How does it change with training or with heart failure?anatomy

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dano7744 eNotes educator| Certified Educator

Cardiac reserve refers to the heart's ability to change the cardiac output instantaneously as needed.  Say you were walking your dog in the park, suddenly the leash broke and your dog ran away, you start running after him. This change from walking to running requires an increase in cardiac output. Cardiac reserve allows the heart to increase the amount of blood it pumps thoughout the cardiovascular system.

When people train aerobically, they vastly improve cardiovascular tone and cardiac reserve. If you are in good cardiovascular shape you can chase after the dog much more efficiently than if you were in poor shape.

In congestive heart failure (CHF, failure) cardiac reserve and cardiac output are diminished because the myocardium is failing as a pump.