We describe the case of a 17-year-old male soccer player with T-wave inversion in precordial leads in resting electrocardiography, which also disclosed sinus bradycardia, early repolarization, and increased QRS voltage. These findings strongly suggested cardiomyopathy. The patient’s T-wave inversion disappeared during only 2 weeks of detraining, and it re-appeared 2 weeks after resumption of intensive training. This sudden change in electrocardiographic parameters over a short period helped in identifying the adolescent as having athlete’s heart.

Chronic physical training has been shown to produce multiple changes in the heart, resulting in the athlete’s heart phenotype. Some of the changes can make it difficult to discern athlete’s heart from true cardiac disease, most notably hypertrophic cardiomyopathy. Other diseases such as dilated cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy may be difficult to rule in or out. In this article, the physiological cardiac changes of chronic athletic training are reviewed. A methodological approach using electrocardiography and echocardiography to differentiate between athlete’s heart and cardiac disease is proposed.

The cardiovascular benefits of habitual exercise are well documented. In the current era, more of the population is exceeding the recommendations for physical activity as the popularity of endurance events increases. Recent data have proposed a U-shaped relationship between exercise intensity and cardiovascular outcomes. Regular participation in endurance activities has been shown to result in structural and functional changes in the heart. This re-modelling may be the substrate for cardiac dysfunction or arrhythmias. The risk of sudden cardiac death may also be elevated; however, in most cases of sudden cardiac death, the cause can be linked to an underlying cardiac pathology where exercise acted as the trigger for a lethal arrhythmia. This article serves to review whether excessive exercise may result in harm in some athletes.