The aim of this study was to assess the effects of endurance training on myocardial regional systolic and diastolic function by pulsed Doppler tissue imaging (DTI). Twenty male water polo players and 20 male control subjects underwent standard Doppler echocardiography and pulsed DTI, performed in apical views by placing a sample volume on left ventricular (LV) basal septal and inferior walls. Age, body surface area, and blood pressure were comparable between the 2 groups, with lower heart rate in athletes (p <0.001). They had significantly increased LV mass index (due to both higher wall thickness and end-diastolic diameter), greater endocardial fractional shortening, higher transmitral early/atrial (E/A) peak velocities ratio. In athletes, DTI analysis showed significantly prolonged myocardial deceleration time and greater myocardial E/A peak velocity ratio of septal and inferior walls, whereas myocardial early peak velocity was increased (p <0.01) only at the inferior wall. In the overall group, we found univariate relations of septal and inferior E/A peak velocity ratio and myocardial deceleration time with LV mass levels, and, in particular, with the sum of wall thickness. By separate multivariate analyses, however, these relations disappeared, being dependent on heart rate degree. Another association found between LV end-diastolic diameter and myocardial early diastolic wave peak velocity of the inferior wall (r = 0.68, p <0.0001) remained significant (standardized beta coefficient 0.60, p <0.00001), even after adjusting for heart rate, body surface area, age, and stroke volume (R(2) = 0.71, p <0.00001). In conclusion, DTI is a useful tool for detecting regional changes in myocardial function induced by training, because athletes present with an improvement in diastolic passive properties of myocardium. The higher early diastolic velocity of the inferior wall and its relation to increased preload may represent an indicator of aerobic training, allowing quantification of the degree of LV adaptation to endurance exercise.