The aim of this study was to examine the reproducibility of cardiac output (Q) measured by Doppler echocardiography and CO2-rebreathing in prepubertal children during exercise. Fourteen healthy children (8 girls and 6 boys aged 10.9 ± 0.9 years) underwent a progressive maximum upright cycle test until exhaustion on two separate occasions (1 week apart). Q was determined successively by the two methods at rest and during the final minutes of each workload. The reproducibility of the Doppler method was higher than the reproducibility of the CO2-rebreathing method, both at rest and during exercise. Moreover, this reproducibility was lower during high intensity exercise whatever the method used. On account of its high reproducibility, Doppler echocardiography should be preferentially used to detect changes in Q as a result of an exercise training intervention in prepubertal children.
Stéphane Nottin, Agnès Vinet, Anne-Marie Lecoq, and Patrick Guenon are with the Laboratoire de la Performance Motrice, Faculté du Sport et de l’Education Physique, Université d’Orléans La Source, rue de Vendôme, BP 6237, 45062 Orléans cedex 2. Philippe Obert is with the Laboratoire de Physiologie des Adaptations Cardiovasculaires à l’Exercice, Faculté des Sciences, Département STAPS, 33 rue Louis Pasteur, 84000 Avignon.