We assessed segmental and global left ventricular (LV) systolic function using tissue Doppler imaging (TDI) in 30 subjects (age: 18-62 y) before and after a marathon race. Longitudinal plane systolic (S') TDI velocities were assessed at 5 sites on the mitral annulus and radial plane S' velocities were assessed at the LV septal and free wall in a subsample (n = 9). Heart rate (HR) and LV diastolic internal dimension were also assessed before (pre) and immediately after (post) the race. Pre-post changes in all variables were analysed by repeated measures analysis of variance (ANOVA). Delta scores for TDI data were correlated with alterations in indices of LV loading, as well as with age and finishing time. Segmental longitudinal and radial TDI velocities were not significantly different pre to post race (p > 0.05), which resulted in no change in mean S' velocities (longitudinal: pre 17.0 +/- 3.4 cm x s(-1), post 17.4 +/- 4.0 cm x s(-)1; radial: pre 13.0 +/- 5.4 cm x s(-1), post 14.2 +/- 7.1 cm x s(-1); p > 0.05). Any pre-post changes in TDI data were not related to an elevated post race HR (r = 0.15, p > 0.05), a decreased post race LV internal dimension in diastole (r = 0.10, p > 0.05), age (r = -0.25, p > 0.05), or finishing time (r = -0.13, p > 0.05). Our data suggest that marathon running does not induce any segmental or global depression in LV systolic function.