Impact of Sporting Disciplines and Body Size on the Athlete’s Heart

Abstract

Regular intensive exercise leads to a series of electrical, structural, and functional changes in the heart, collectively named as the “athlete’s heart”. Sporting discipline has an impact on cardiac adaptation to exercise. Endurance athletes tend to exhibit a significant biventricular enlargement and highly trained cyclists can be characterized by a low normal or even reduced left ventricular ejection fraction at echocardiography. Normal left ventricular geometry prevails in most highly trained athletes; however, while female athletes engaged in dynamic exercise show a greater prevalence of eccentric hypertrophy, male athletes may exhibit concentric hypertrophy/remodeling more frequently than female athletes although the absolute numbers are low. Body size is also strongly associated with cardiac dimensions. The interpretation of cardiac dimensions in any athlete should be based on body-size independent cardiac indices as this facilitates the differential diagnosis of physiological versus pathological cardiac adaptation in athlete screening. Historically, scaling of cardiac data in athletes for individual differences in body size has been either entirely ignored or has used simple “ratiometric” scaling such as normalization of LV mass for individual differences in BSA (LV mass/BSA). We argue that this scaling process may not always be theoretically or practically accurate, resulting in cardiac indices that are still body size-dependent. This only confuses clinical decision-making. An “allometric” approach to scaling is theoretically sound in most cases and practically tends to lead to body size-independent cardiac indices. This evidence-based approach should be encouraged wherever possible and specifically within the sphere of sports cardiology and pre-participation screening. A correct understanding of determinants, type and extent of physiological cardiac adaptation is pivotal to correctly differentiate normal findings from potentially fatal cardiac diseases such as cardiomyopathies.