title: Comparison of mechanical ventilatory constraints between continuous and intermittent exercises in healthy prepubescent children.
abstract: BACKGROUND
  The aim of this study was to evaluate the occurrence and severity of mechanical ventilatory constraints in healthy prepubescent children during continuous and intermittent exercise.
  
  
  METHODS
  Twelve prepubescent children (7-11 years old) performed 7 exercises on a treadmill: one graded test for the determination of maximal aerobic speed (MAS), three continuous exercises (CE) at 60, 70, and 80% of MAS and three intermittent exercises (IE), alternating 15 sec of exercise with 15 sec of passive recovery, at 90, 100, and 110% of MAS. During each CE and IE, tidal flow/volume loops were plotted within a maximal flow/volume loop (MFVL) measured at rest before each exercise. Expiratory flow limitation (expFL expressed in %Vt) was defined as the part of exercise tidal volume (Vt) meeting the boundary of MFVL. Breathing strategy was estimated by measuring inspiratory capacity relative to forced vital capacity and tidal volume relative to inspiratory capacity. Other breathing pattern parameters (ventilation VE, Vt, respiratory frequency f) were continuously recorded during exercise.
  
  
  RESULTS
  An "intensity" effect was found for VE during CE (P < 0.001) but not during IE (P = 0.08). The increase in VE was predominantly assumed by an increase in f for both exercise modalities. During each exercise, several children heterogeneously experienced expFL ranging between 10 and 90%Vt. For all exercises, Vt was predominantly regulated by an increase in Vt/IC with no change in IC/FVC from rest to exercise. Finally, no significant "modality" effect was found for mechanical ventilatory constraint parameters (expFL, Vt/IC, and IC/FVC).
  
  
  CONCLUSIONS
  We could conclude that neither of the modalities studied induced more mechanical ventilatory constraints than the other, but that exercise intensities specific to each modality might be greater sources of exacerbation for mechanical ventilatory constraints.
authors.affiliation: Univ Lille Nord de France, Lille, France.
authors.forename: Benoit
authors.initials: B
authors.lastname: Borel
authors.forename: Erwan
authors.initials: E
authors.lastname: Leclair
authors.forename: Delphine
authors.initials: D
authors.lastname: Thevenet
authors.forename: Laurent
authors.initials: L
authors.lastname: Beghin
authors.forename: Frédéric
authors.initials: F
authors.lastname: Gottrand
authors.forename: Claudine
authors.initials: C
authors.lastname: Fabre
mesh_terms: D002648:Child; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics