title: Mechanical ventilatory constraints during incremental exercise in healthy and cystic fibrosis children.
abstract: OBJECTIVE
  To analyze breathing pattern and mechanical ventilatory constraints during incremental exercise in healthy and cystic fibrosis (CF) children.
  
  
  METHODS
  Thirteen healthy children and 6 children with cystic fibrosis volunteered to perform an incremental test on a treadmill. Exercise tidal flow/volume loops were plotted every minute within a maximal flow/volume loop (MFVL). Expiratory flow limitation (expFL expressed in %Vt) was evaluated and end-expiratory and end-inspiratory lung volumes (EELV and EILV) were estimated from expiratory reserve volume relative to vital capacity (ERV/FVC) and from inspiratory reserve volume relative to vital capacity (IRV/FVC).
  
  
  RESULTS
  During the incremental exercise, expFL was first observed at 40% of maximal aerobic speed in both groups. At maximal exercise, 46% of healthy children and 83% of CF children presented expFL, without significant effect of cystic fibrosis on the severity of expFL. According to the two-way ANOVA results, both groups adopted similar breathing pattern and breathing strategies as no significant effect of CF has been revealed. But, according to one-way ANOVA results, a significant increase of ERV/FVC associated with a significant decrease of IRV/FVC from resting value shave been observed in healthy children at maximal exercise, but not in CF children.
  
  
  CONCLUSIONS
  The hypothesis of this study was based on the assumption that mild cystic fibrosis could induce more frequent and more severe mechanical ventilatory constraints due to pulmonary impairment and breathing pattern disturbances. But, this study did not succeed to highlight an effect of mild cystic fibrosis on the mechanical ventilatory constraints (expFL and dynamic hyperinflation) that occur during an incremental exercise. This absence of effect could be due to the absence of an impact of the disease on spirometric data, breathing pattern regulation during exercise and breathing strategy.
authors.affiliation: Univ Lille Nord de France, Lille, France; UDSL, EA 4488, Faculté des Sciences du Sport et de l'Education Physique, Ronchin, 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: D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D003550:Cystic Fibrosis / Q000503:physiopathology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008176:Lung Volume Measurements; D008297:Male; D012123:Pulmonary Ventilation / Q000502:physiology; D015656:Respiratory Mechanics / Q000502:physiology*; D013147:Spirometry; D013990:Tidal Volume / Q000502:physiology; D014797:Vital Capacity / Q000502:physiology
keywords: breathing pattern; dynamic hyperinflation; expiratory limitation; prepubescent children