Background: Long term athletic training is associated with an increase in left ventricular diastolic cavity dimensions, wall thickness, and mass. These changes are described as the "athlete's heart". In comparison to men, athletic training in women athletes is not a stimulus for substantial increase in left ventricular wall thickness. Although many variables are related to these gender differences in cardiac morphology, some factors such as 24-h blood pressure and the level of training have not been studied yet. Therefore pairs in sport dancing, in which the level of training of both partners is the same, were chosen as models in order to evaluate whether 24-h blood pressure contributes to sex-related differences in an athlete's heart.
Methods: Fifteen pairs in the national sport dancing team and 30 control subjects (15 males, 15 females) were studied. In all subjects casual and 24-h ambulatory blood pressures, echocardiography, and maximal stress testing were performed.
Results: Female in comparison to male dancers had significantly lower M-mode (P<0.004) and 2-D left ventricular mass index (P<0.001), 24-h systolic blood pressure (P<0.003), day systolic blood pressure (P<0.002), casual systolic blood pressure (P<0.025), and achieved significantly lower peak systolic blood pressure at stress testing (P<0.004). Multiple stepwise regression analysis showed that the best predictors of 2-D left ventricular mass index are maximal work load and peak exercise systolic blood pressure, 24-h systolic blood pressure, day, and casual systolic blood pressure.
Conclusions: Lower left ventricular mass index in female dancers can be partly explained by lower systolic blood pressures during 24-h and at exercise.