Aims: We sought to investigate the systolic time interval (STI) and efficiency of left ventricular (LV) contraction comparatively in elite athletes and healthy sedentary controls by means of three-dimensional echocardiography (3DE).

Methods and results: Four hundred and twenty-nine elite athletes, involved in skill (n = 41), power (n = 63), mixed (n = 167), and endurance (n = 158) disciplines and 98 sedentary controls, matched for age, underwent 3DE. By off-line analysis, we measured the absolute and relative (normalized by the R-R interval) timing of LV systolic emptying (STI and STI%) and the systolic flow velocity (SFV = stroke volume/STI). Both STI and STI% were shorter in athletes, regardless of the sport discipline, compared with controls (respectively, 324 ± 36 vs. 345 ± 33 ms, P < 0.001; 30 ± 4 vs. 40 ± 4%; P< 0.001). Regression analysis showed that heart rate was the most important determinant of STI (R(2) = 0.38; P < 0.001), while age, body surface area, blood pressure, LV volumes, and mass had no significant association. After removing the effects of heart rate and gender, athletes showed a significant reduction (by 50.4 ms; 95% confidence interval, from 57.7 to 43.1) in STI compared with untrained subjects. Finally, higher SFV were identified in skill (256 ± 60 mL/s; P < 0.001), strength (297 ± 78 mL/s; P < 0.001), mixed (308 ± 67 mL/s; P < 0.001), and endurance (334 ± 74 mL/s; P < 0.001) athletes compared with controls (204 ± 50 mL/s).

Conclusion: Elite athletes show a significant shortening of the systolic time duration in comparison with sedentary controls, in association with a significant increase in LV emptying velocity. This pattern characterizes the physiological LV adaptation of the athletes and may potentially be useful in differential diagnosis of the 'athlete heart'.