An enlarged heart is, per its name, an increase in the size of the heart. While this condition can be caused by a number of factors, in runners it is typically symptomatic of the thickening of heart muscle resulting from frequent exercise. A certain amount of increase in heart size is to be expected from running, though runners should also be wary of certain risks that accompany the condition.
Causes
An enlarged heart can be caused by a number of different factors. Running naturally strengthens the heart muscle and can prompt an increase in size. However, runners may also have an enlarged heart due to other reasons, such as heart valve disease or high blood pressure. Certain parts of the heart may be enlarged as well; left ventricular hypertrophy is characterized by increasing size of the left ventricle, for instance.
Hypertrophic Cardiomyopathy
An especially risky type of enlarged heart condition that runners face is known as hypertrophic cardiomyopathy, in which the muscles of the heart's walls thicken abnormally. Hypertrophic cardiomyopathy is a significant cause of sudden death among athletes under age 35. The condition creates an abnormal heart rhythm that can prove fatal to runners in some cases. Many runners might train for years with hypertrophic cardiomyopathy before noticing symptoms.
Diagnosis
Since an enlarged heart is a natural byproduct of running, ascertaining risk requires a deeper examination. In addition to size, doctors often look at the thickness of the heart's walls. Thickness may determine how hard the heart must pump blood to the rest of the body and may indicate hypertrophic cardiomyopathy, abnormal coronary arteries or a pulling apart of heart tissue --- all potentially fatal conditions to the runner.
Recent Incidents
The effects of an enlarged heart were illustrated tragically at the 2007 New York City Marathon, during which elite runner Ryan Shay died in the early miles of the race. Although the actual cause of death was inconclusive, Shay's confirmed diagnosis of an enlarged heart led many to speculate that the condition contributed to the tragedy. Other factors are just as capable of proving fatal in running, however, including calcium deposits in the arteries or coronary artery disease.
Considerations
A runner who is diagnosed with an enlarged heart must ask herself whether continued running is worth the potential risks. Many elite runners with enlarged hearts pass extensive performance tests with ease, yet some still succumb to the inherent risks, as Shay did in 2007. In the long run, the more information a runner can obtain about her condition, the better she can ascertain the risks of running.
