Do athletes have “the athlete heart?”

Abstract

In 1897 Henschen’ used cutaneous percussion to examine the hearts of cross-country skiers and reported that those with larger hearts also had better placements in the race. Nearly 100 years later and after several hundred publications, the significance of this observation is still debated. The term, “athlete heart,” was introduced to describe the cardiovascular effects of exercise in competitive athletes. Two decades ago accurate direct in vivo measurements of cardiac structures became feasible for the first time with the introduction of echocardiography. Between 1975 and 1992, more than 80 studies compared left ventricular (LV) morphology in more than 1000 nonathletes and athletes with endurance or strength fitness (Table l), and 20 other studies examined the changes in LV structure of healthy sedentary individuals following predominantly endurance-type training programs (Table 2). The common interpretation of these observations is that regular physical activity induces cardiac hypertrophy . However, a large number of confounding factors have not been considered in the interpretation of these data. This paper will critically review the scientific literature concerning cardiac morphological adaptations to training in humans that suggests that athletes, in fact, may have rather “normal” cardiac dimensions. Address correspondence to Dr. Helene M. Perrault, Service de Cardiologie et de Medecine Pulmonaire, HBpital Ste-Justine, 3175 Chemin Cote Ste-Catherine, Montreal, Quebec, Canada, H3T lC5. MORPHOLOGY OF THE ATHLETE HEART: REVIEW OF ECHOCARDIOCRAPHIC DATA Two different methodological approaches have been used in the echocardiographic examination of cardiac morphology. Studies with cross-sectional design have compared LV structures of athletes involved in different sport disciplines to those of sedentary “nonathletes,” whereas studies with longitudinal design have examined changes in these structures before and after several weeks or months of regular physical training. In most studies LV enddiastolic measurements have included internal diameter (LVEDD) and posterior wall thickness (LVPW), with interventricular septal wall thickness reported in only some cases. The results of a metaanalysis of findings from cross-sectional comparisons of sedentary controls to endurance- or strengthtrained athletes appear in Figures 1 and 2, respectively (see Table 1 for references). The average LV dimensions calculated from the reported group means in each study is shown as well as the weighted mean, calculated from the overall average of group means, weighted for the number of individual observations in each group. As seen in Figure 1, no difference can be observed between weighted means and group means of endurance athletes or their sedentary controls, reflecting the homogeneity in echocardiographic measurements of LV structures both in these athletes and in controls. Statistical analysis of the results indicates significant differences in LV morphological charac