Two-dimensional echocardiography was used to determine the responses of left ventricular volumes, ejection fraction and segmental left ventricular motion to supine dynamic exercise in 22 professional athletes, comparing these responses with those in 22 age- and gender-matched healthy untrained individuals. End-systolic volume was significantly greater at rest and during exercise in the athletes (50 ± 6 versus 29 ± 4 ml and 40 ± 5 versus 17 ± 4 ml, respectively, p < 0.001 for both). It decreased during exercise in all the untrained subjects, but did not change or increased in nine athletes (41%). End-diastolic volume was greater in the athletes at rest (143 ± 12 versus 98 ± 9 ml) and during exercise (157 ± 14 versus 121 ± 13 ml, p < 0.01 for both). It increased in all the untrained subjects, but decreased or did not change in six athletes (27%). Ejection fraction was significantly lower in the athletes at rest and during exercise (65 ± 4% versus 70 ± 5% and 73 ± 5% versus 86 ± 5%, p < 0.01 and 0.001, respectively); the values augmented normally in all the untrained subjects, but increased only by <5% units, did not change or decreased in nine athletes (41%). Eight athletes (36.5%) failed to demonstrate the expected symmetric hyperkinetic wall motion changes during exercise, which were seen in all the untrained subjects. No correlation was found between atypical responses to exercise and electrocardiographic patterns. This study demonstrates that ejection fraction at rest and during exercise is significantly lower in athletes, and that some athletes exhibit altered left ventricular volume responses to exercise, accompanied by segmental wall motion abnormalities.