Background: The aim of the study was to analyze the differences in myocardial function in case of left ventricular (LV) hypertrophy induced by either endurance or strength training in top-level athletes.
Methods: Standard Doppler echo and pulsed Doppler tissue imaging (DTI) of the interventricular septum and of the LV inferior wall were performed in 26 competitive endurance athletes (long-distance swimmers) (group A) and in 20 strength-trained athletes (short-distance swimmers) (group B). By means of DTI, the following parameters of myocardial function were assessed: the systolic peak velocities (Sm), the pre-contraction time, the contraction time, the early (Em) and late (Am) diastolic velocities, the Em/Am ratio and the relaxation time.
Results: The two groups were comparable for age and sex, but at rest group B showed a higher heart rate, systolic blood pressure and body surface area. The LV mass index and fractional shortening did not significantly differ between the two groups. However, group B showed an increased sum of the wall thicknesses (septum + posterior wall) (p < 0.001) and of the relative wall thickness, while the LV stroke volume and LV end-diastolic diameter (p < 0.001) were greater in group A. All transmitral Doppler indexes were higher in group A, with an increased E/A ratio. DTI analysis showed, in group A, a higher Em and Em/Am ratio as well as a longer relaxation time both at the septal and at the inferior wall levels, with comparable Sm, pre-contraction and contraction times. Distinct multiple linear regression models revealed an independent positive association between the inferior peak Em velocity and the LV end-diastolic diameter (p < 0.001) in group A, and an independent direct correlation of the inferior peak Sm velocity with the sum of the wall thicknesses (p < 0.001) and with the end-systolic stress in group B.
Conclusions: The early diastolic myocardial function is positively influenced by the preload increase in group A, while an increased afterload and LV wall thickness in group B mainly seem to induce an enhancement of the regional myocardial systolic function.