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Heart of a Champion: What is Athlete’s Heart?

You’re All Heart

Your body adapts to hard athletic training by increasing muscularity, agility, reaction time, speed, power and performance. Just like the muscles that govern movement, your heart muscle also adapts to overload, becoming bigger and stronger. The increase is most noticeable in the left ventricle, where oxygenated blood is ejected into the arteries to be circulated to the cells.

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Athlete’s Heart vs CHF

The increase in ventricular size, called left ventricular hypertrophy, was once a concern to doctors, who saw similar growth in the left ventricles of congestive heart failure (CHF) patients. But in CHF, the heart tissue becomes stretched and flabby from trying to pump blood into a resistive circulatory system. The resistance is due to back pressure from clogged and hardened arteries in patients with heart disease.

Lay it on Thick

Unlike CHF, the enlarged heart of an athlete is a result of training, where the heart muscle tissue grows stronger and thicker. The myocardium, or heart muscle, surrounds the chamber of the left ventricle, contracting to eject blood into the systemic circulation. In athletes, the ventricular walls become thick with muscle, translating to a larger diameter.

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Turn Up the Volume

In addition to the ventricular walls becoming thicker and stronger, the diameter of the chamber increases, allowing for a greater volume of blood to be ejected with each stroke. Increased circulating blood volume and increased arterial diameter enable the oxygen delivery system to function at optimal levels, meaning that cellular respiration can take place at an increased rate. All of this adds up to improved oxygen delivery, increased endurance and delayed fatigue.


To understand more about cardiac adaptations to exercise, become a Certified Personal Trainer or register for the W.I.T.S. Personal Trainer Foundations course online.

References and Credits

Circulation: The Heart of Trained Athletes


Circulation: Left Ventricular Hypertrophy


*Images courtesy of

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