title: Skeletal Muscle Function in Young Patients With Cystic Fibrosis.
abstract: Defects in the gene encoding the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) cause CF. Absence of the CFTR may result in skeletal muscle dysfunction. Here, we tested skeletal muscle function in male adolescent patients with CF.
  
  
  
  Ten CF and 10 control participants (age: 16.8 ± 0.6 years) performed 7 repetitive sets of maximum voluntary contractions (MVCs) and underwent an isometric fatigue test of the knee extensors. Electromyography (EMG) activity was recorded from the m. vastus lateralis (VL) and m. vastus medialis (VM).
  
  
  
  In CF, the MVC torque was lower and correlated with the predicted forced expiratory volume in one second (r = .73, p = .012, n = 10). The M-wave in the VL was shorter in CF than in controls (18.6 ± 0.5 vs. 20.3 ± 0.5 ms, p < .028). In the VM, both the M-wave (4.96 ± 0.61 vs. 7.97 ± 0.60 mV, p = .001) and the EMG (0.29 ± 0.04 vs. 0.47 ± 0.04 mV, p = .004) amplitudes were smaller in CF.
  
  
  
  The differences in the VL and VM EMG signals between the groups indicate that the lower MVC torque in CF did not result from the direct impact of a CFTR defect on the sarcolemmal excitability; the differences more likely resulted from the less developed musculature in the patients with CF.
authors.affiliation: Hannover Medical School, Institute of Sports Medicine, Hannover, Germany.
authors.forename: Lothar
authors.initials: L
authors.lastname: Stein
authors.forename: Constanze
authors.initials: C
authors.lastname: Pacht
authors.forename: Sibylle
authors.initials: S
authors.lastname: Junge
authors.forename: Tobias S
authors.initials: TS
authors.lastname: Kaeding
authors.forename: Momme
authors.initials: M
authors.lastname: Kück
authors.forename: Norbert
authors.initials: N
authors.lastname: Maassen
authors.forename: Torge
authors.initials: T
authors.lastname: Wittke
authors.forename: Vladimir
authors.initials: V
authors.lastname: Shushakov
mesh_terms: D000293:Adolescent; D016022:Case-Control Studies; D003550:Cystic Fibrosis / Q000503:physiopathology*; D004576:Electromyography; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D018763:Muscle Fatigue; D018482:Muscle, Skeletal / Q000502:physiology*; D010865:Pilot Projects; D011446:Prospective Studies; D019415:Torque