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7436136 
Journal Article 
Athlete’s Heart: Basic Physiology and Adaptation to Exercise 
Schmied, CM; Wilhelm, M; , 
2020 
Springer International Publishing 
Cham 
Textbook of Sports and Exercise Cardiology 
29-51 
The interest in cardiac adaptations to strenuous exercise dates back to the nineteenth century. The athlete’s heart was discovered by physical examination only. Cardiac enlargement in high-level endurance athletes was interpreted as physiological adaptation, although some physicians raised the concern that it could be an overuse pathology. The introduction of the electrocardiogram (ECG) and subsequent imaging modalities improved the understanding of exercise physiology and the structural, electrical and functional adaptations of the heart. The interpretation of the athlete’s ECG and cardiac images requires knowledge of cardiac exercise physiology. Regular endurance exercise of more than 10 h/week usually leads to a harmonic enlargement of all cardiac chambers. Sporting discipline, intensity of sports, body composition, starting age of exercise training, sex, and ethnicity are important contributing factors. Based on cross-sectional data, the Morganroth Hypothesis concluded that the “volume” load during endurance exercise primarily leads to an increase in left ventricular (LV) cavity size and eccentric LV hypertrophy, whereas the “pressure” load during resistance training primarily leads to an increase in LV wall thickness and concentric LV hypertrophy. However, the contemporary view is that endurance exercise is associated with both “volume” and “pressure” load and that cardiac adaptation is a phasic phenomenon, ultimately leading to an eccentric LV hypertrophy pattern. In opposite, concentric LV hypertrophy patterns observed in strength-trained athletes may be related to arterial hypertension and/or anabolic steroid use. Physiological electrical findings in athletes are sinus bradycardia and junctional rhythms, PQ prolongation, increased QRS voltages fulfilling criteria for left ventricular hypertrophy, ST segment elevation in V1 to V4, and tall T waves.