• Heart
• athlete
• exercise physiology
• ventricular remodelling
• sports
• systolic dysfunction
• diastolic dysfunction
• systolic heart failure
• echocardiography
• cardiac function
• stress
• pulmonary arterial hypertension

Athlete's heart is the term given to the complex of structural, functional, and electrical remodelling that accompanies regular athletic training. It is an important physiological adaption which helps athletes perform better in physical tasks than non-athletes and one of the physiological changes that may make a good athlete great. The fact that the heart of an athlete is different to the non-athlete's was recognised in the late 19th century based on clinical examination, with the recognition of cardiac enlargement and bradycardia among more highly trained athletes. Our understanding of this syndrome has gradually expanded in parallel with the development of new invasive and non-invasive tools for the examination of cardiac structure and function. Initially, the chest x-ray and ECG demonstrated important features of cardiac chamber enlargement in athletes. The next steps incorporated invasive haemodynamic measures at rest and with exercise. An additional source of understanding of the athlete's heart has been examination of cardiac pathology specimens. More recently the use of imaging techniques such as echocardiography and cardiac MRI have played a central role in advancing our understanding of what constitutes an athlete's heart and in applying this information in clinical settings.

Study of the athlete's heart has been undertaken and is important for a number of key reasons: first, to understand how cardiac adaptation contributes to improved athletic performance; second, to guide development of training regimens which will optimise cardiac adaptation and thus enhance athletic performance; and third, to allow differentiation of the normal athlete's heart from important disease states which may share similar morphologic features. It is the third of these reasons that has assumed most importance in the cardiology and sports medicine worlds.

The aim of this article is for clinicians to learn about the key features of the athlete's heart and to understand concepts used to …