The athlete's heart - A meta-analysis of cardiac structure and function

Background-It has been postulated that depending on the type of exercise pe rformed, 2 different morphological forms of athlete's heart may be distingu ished: a strength-trained heart and an endurance-trained heart. Individual studies have not tested this hypothesis satisfactorily. Methods and Results-The hypothesis of divergent cardiac adaptations in endu rance-trained and strength-trained athletes was tested by applying meta-ana lytical techniques with the assumption of a random study effects model inco rporating all published echocardiographic data on structure and function of male athletes engaged in purely dynamic (running) or static (weight liftin g, power lifting, bodybuilding, throwing, wrestling) sports and combined dy namic and static sports (cycling and rowing). The analysis encompassed 59 s tudies and 1451 athletes. The overall mean relative left ventricular wall t hickness of control subjects (0.36 mm) was significantly smaller than that of endurance-trained athletes (0.39 mm, P=0.001), combined endurance- and s trength-trained athletes (0.40 mm, P=0.001), or strength-trained athletes ( 0.44 mm, P<0.001). There was a significant difference between the 3 groups of athletes and control subjects with respect to left ventricular internal diameter (P<0.001), posterior wall thickness (P<0.001), and interventricula r septum thickness (P<0.001). In addition, endurance-trained athletes and s trength-trained athletes differed significantly with respect to mean relati ve wall thickness (0.39 versus 0.44, P=0.006) and interventricular septum t hickness (10.5 versus 11.8 mm, P=0.005) and showed a trend toward a differe nce with respect to posterior wall thickness (10.3 versus 11.0 mml P=0.078) and left ventricular internal diameter (53.7 versus 52.1 mm, P=0.055). Wit h respect to cardiac function, there were no significant differences betwee n athletes and control subjects in left ventricular ejection fraction, frac tional shortening, and E/A ratio. Conclusions-Results of this meta-analysis regarding athlete's heart confirm the hypothesis of divergent cardiac adaptations in dynamic and static spor ts. Overall, athlete's heart demonstrated normal systolic and diastolic car diac functions.