title: Skeletal muscle contractility and fatigability in adults with cystic fibrosis.
abstract: BACKGROUND
  Recent discovery of cystic fibrosis transmembrane conductance regulator expression in human skeletal muscle suggests that CF patients may have intrinsic skeletal muscle abnormalities potentially leading to functional impairments. The aim of the present study was to determine whether CF patients with mild to moderate lung disease have altered skeletal muscle contractility and greater muscle fatigability compared to healthy controls.
  
  
  METHODS
  Thirty adults (15 CF and 15 controls) performed a quadriceps neuromuscular evaluation using single and paired femoral nerve magnetic stimulations. Electromyographic and mechanical parameters during voluntary and magnetically-evoked contractions were recorded at rest, during and after a fatiguing isometric task. Quadriceps cross-sectional area was determined by magnetic resonance imaging.
  
  
  RESULTS
  Some indexes of muscle contractility tended to be reduced at rest in CF compared to controls (e.g., mechanical response to doublets stimulation at 100 Hz: 74±30 Nm vs. 97±28 Nm, P=0.06) but all tendencies disappeared when expressed relative to quadriceps cross-sectional area (P>0.5 for all parameters). CF and controls had similar alterations in muscle contractility with fatigue, similar endurance and post exercise recovery.
  
  
  CONCLUSIONS
  We found similar skeletal muscle endurance and fatigability in CF adults and controls and only trends for reduced muscle strength in CF which disappeared when normalized to muscle cross-sectional area. These results indicate small quantitative (reduced muscle mass) rather than qualitative (intrinsic skeletal muscle abnormalities) muscle alterations in CF with mild to moderate lung disease.
authors.affiliation: Grenoble-Alpes University, HP2 Laboratory, 38000 Grenoble, France; INSERM, U1042, 38000 Grenoble, France; LAMHESS EA 6312, Universities of Toulon and Nice Sophia-Antipolis, France. Electronic address: gruet@univ-tln.fr.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Gruet
authors.affiliation: Grenoble-Alpes University, HP2 Laboratory, 38000 Grenoble, France; INSERM, U1042, 38000 Grenoble, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Decorte
authors.affiliation: LAMHESS EA 6312, Universities of Toulon and Nice Sophia-Antipolis, France; Regional Cystic Fibrosis Unit (CRCM), Renée Sabran Hospital, Giens, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Mely
authors.affiliation: LAMHESS EA 6312, Universities of Toulon and Nice Sophia-Antipolis, France.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Vallier
authors.affiliation: Regional Cystic Fibrosis Unit (CRCM), Thoracic and Vascular Department, Grenoble University Hospital, France.
authors.forename: Boubou
authors.initials: B
authors.lastname: Camara
authors.affiliation: Regional Cystic Fibrosis Unit (CRCM), Thoracic and Vascular Department, Grenoble University Hospital, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Quetant
authors.affiliation: Grenoble-Alpes University, HP2 Laboratory, 38000 Grenoble, France; INSERM, U1042, 38000 Grenoble, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Wuyam
authors.affiliation: Grenoble-Alpes University, HP2 Laboratory, 38000 Grenoble, France; INSERM, U1042, 38000 Grenoble, France.
authors.forename: Samuel
authors.initials: S
authors.lastname: Verges
mesh_terms: D000328:Adult; D003550:Cystic Fibrosis / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D008171:Lung Diseases / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology*; D052097:Quadriceps Muscle / Q000503:physiopathology; D012720:Severity of Illness Index
chemical_list: D019005:Cystic Fibrosis Transmembrane Conductance Regulator
keywords: Cystic fibrosis; Exercise tolerance; Neuromuscular fatigue; Skeletal muscle function