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Exercise flow-volume loops in prepubescent aerobically trained children

¹Laboratoire 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; ²Laboratoires d'Etudes de la Motricité Humaine EA 3608, Faculté des Sciences du Sport et de l'Education Physique, Université de Lille 2, Ronchin; ³Service 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 (VT) 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 VT 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 VT), 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_O2 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_O2 level and dyspnea during strenuous exercise.

mechanical ventilatory constraints; expiratory limitation; dynamical hyperinflation; training; healthy children