AIM: Previous reports indicate that the "athlete`s heart" is more prominent in males than females, but the mechanisms responsible for this sex difference have not been elucidated. This study examined male-female differences in cardiac mass and volume in highly trained athletes and normally active individuals to assess the relative contributions of pre-existing sex differences and sports training to cardiac findings. METHODS: Echocardiographic and electrocardiographic findings were compared between 20 male and 21 female collegiate athletes and 22 male and 29 female normally-active subjects. RESULTS: Cardiac mass (per kg lean body mass) was significantly greater in the male compared to female athletes (3.62±0.55 and 3.31±0.56 g.kg-1, respectively). A similar magnitude of difference in average relative cardiac mass was observed between the normally active males and females, and cardiac mass was greater in athletic versus nonathletic groups by +14.9% in the males and +13.3% in the females. Relative left ventricular volume was greater in the male athletes (47.5±6.3 ml•BSA-1.5) compared to male nonathletes (42.9±6.1 ml•BSA-1.5); no such difference was observed in the females. CONCLUSION: These findings suggest that sex differences in both the untrained state and magnitude of training response contribute to male-female differences in the "athlete`s heart".
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