Aortic flow velocity indices during upright exercise: reliability and relationship to cardiac output.

Objective: To determine the intra- and interobserver reproducibility of Doppler-derived ascending aortic flow velocity measurements at rest and during upright exercise of increasing intensity; and to determine the relationship between Doppler-derived measurements and cardiac output obtained by the indirect Fick carbon dioxide rebreathing method in the same conditions.

Subjects: Twenty young healthy adults participated in the study; eight participated in the first part and 12 in the second.

Design: For the intra-observer study, subjects were submitted to three workloads (50, 100 and 150 W) of 5 mins duration on two occasions, seven days apart.