Objectives: We examined the echocardiographic characteristics of highly trained American football players.
Background: Intense physical training is associated with morphologic and physiologic cardiac changes often referred to as the "athlete's heart." Echocardiographic features peculiar to elite football players have not been described.
Methods: We studied cardiac morphology and function as assessed by rest and stress echocardiography in 156 asymptomatic National Football League players. Resting and stress ejection fraction (EF), wall thickness, and diastolic left ventricular internal diameter (LVID) were measured. Left ventricular (LV) mass was calculated, as was relative wall thickness (RWT) defined as septal and posterior wall thickness divided by LVID. Control data were obtained from published studies.
Results: The mean LVID (53 +/- 0.5 mm) and maximal wall thickness (11.2 +/- 0.2 mm) were increased over normal reported control subjects. There was a correlation between LVID and body weight (p = 0.01) and body surface area (BSA) (p = 0.01). The average LVID indexed to BSA was 23 +/- 2 mm/M(2). There was also a correlation between maximal wall thickness and body weight (p = 0.01) and BSA (p = 0.01). The average wall thickness indexed to BSA was 5.05 +/- 0.88 mm/M(2). Of the players, 23% had evidence of LV hypertrophy. Two players had an increased septal-to-posterior-wall-thickness ratio (> or =1.3), although no player had an outflow gradient. The RWT for the players was 0.424 (+/- 0.1). The mean resting EF was 58% (+/- 4.4%), and every player undergoing exercise testing had an appropriate hyperdynamic response in cardiac function.
Conclusions: Both wall thickness and LVID of elite American football players are increased and correlate with body size. There is a high RWT, reflecting an emphasis on strength training. The LV EF was normal and not supranormal, as is sometimes believed. Regardless of the resting EF, all players had hyperdynamic cardiac responses with exercise.