Exercise flow-volume loops in prepubescent aerobically trained children

1 Laboratoire d'Analyse Multidisciplinaire des Pratiques Sportives, Unité de Formation et de Recherche des Sciences et Techniques des Activités Physiques et Sportives de Liévin, Université d'Artois, Chemin du Marquage, Liévin; 2 Laboratoires d'Etudes de la Motricité Humaine EA 3608, Faculté des Sciences du Sport et de l'Education Physique, Université de Lille 2, Ronchin; 3 Service de pneumologie, Hôpital Germon-Gauthier de Béthune-Beuvry, Beuvry, France Submitted 21 March 2005 ; accepted in final form 4 July 2005 We studied mechanical ventilatory constraints in 13 aerobically trained (Tr) and 11 untrained (UT) prepubescent children by plotting the exercise flow-volume (F-V) loops within the maximal F-V loop (MFVL) measured at rest. The MFVL allowed to determine forced vital capacity (FVC) and maximal expiratory flows. Expiratory and inspiratory reserve volumes relative to FVC (ERV/FVC and IRV/FVC, respectively) were measured during a progressive exercise test until exhaustion. Breathing reserve (BR) and expiratory flow limitation (expFL), expressed in percentage of tidal volume (V T ) and defined as the part of the tidal breath meeting the boundary of the MFVL, were measured. Higher FVC and maximal expiratory flows were found in Tr than UT ( P < 0.05) at rest. Our results have shown that during exercise, excepting one subject, all Tr regulated their V T within FVC similarly during exercise, by breathing at low lung volume at the beginning of exercise followed breathing at high lung volume at strenuous exercise. In UT, ERV/FVC and IRV/FVC were regulated during exercise in many ways. The proportion of children who presented an expFL was nearly the same in both groups ( 70% with a range of 14 to 65% of V T ), and no significant difference was found during exercise concerning expFL. However, higher ventilation ( E ), ERV/FVC, and dyspnea associated with lower BR, IRV/FVC, and Sa O 2 were reported at peak power in Tr than UT ( P < 0.05). These results suggest that, because of their higher E level, trained children presented higher ventilatory constraints than untrained. These may influence negatively the Sa O 2 level and dyspnea during strenuous exercise. mechanical ventilatory constraints; expiratory limitation; dynamical hyperinflation; training; healthy children Address for reprint requests and other correspondence: C. Nourry, UFR des STAPS de Liévin, Laboratoire d'Analyse Multidisciplinaire des Pratiques et Sportives, Chemin du Marquage, 62800 Liévin, Franc