Importance of the athlete's heart has been arisen in the last decades.<ul> Consequences of the sedentary way of life are the most threatening through the impairments of the cardiovascular system. Endurance performance is mostly limited by the characteristics of the athlete's heart. Sudden death of the athletes is always associated with cardiac disorders. </ul>Main characteristics of the athlete's heart can be divided into morphologic, functional and regulatory ones.<ul> The main morphologic characteristics are the physiologic left ventricular (LV) hypertrophy and a richer coronary capillary network. The functional adaptation contains a better systolic and diastolic function, modified metabolism and electric characteristics. The most easily detected modification is the better LV diastolic function. Adaptation of the cardiac regulation is manifested mostly by a lower heart rate (HR). </ul>Summarizing: the athlete's heart is an enlarged but otherwise normal heart characterized by a low heart rate, an increased pumping capacity, and a greater ability to deliver oxygen to skeletal muscle.