title: Effect of endurance exercise on respiratory muscle function in patients with cystic fibrosis.
abstract: During exercise, patients with cystic fibrosis (CF) dynamically hyperinflate, which imposes both elastic and threshold loads on the inspiratory muscles and places them at a mechanical disadvantage due to muscle shortening. Conversely, dynamic hyperinflation imposes a progressively resistive load and lengthens the expiratory muscles potentially increasing their susceptibility to develop low frequency fatigue (LFF). The aim of the study was to determine whether high intensity endurance exercise leads to the development of LFF in either the diaphragm or expiratory abdominal wall muscles in patients with CF. Ten patients and ten healthy individuals were studied. Twitch transdiaphragmatic pressure (TwP(di)) and twitch abdominal pressure (TwT(10)) were measured before and after exhaustive endurance cycle exercise at 80% of their previously determined maximum work rate. There was no difference in TwP(di) or TwT(10) at 20, 40 or 60 min post exercise compared to pre-exercise resting values in any of the participants, indicating that overt LFF of the respiratory muscles did not develop.
authors.affiliation: King's College London School of Medicine, UK. charles.c.reilly@kcl.ac.uk
authors.forename: Charles C
authors.initials: CC
authors.lastname: Reilly
authors.forename: Katie
authors.initials: K
authors.lastname: Ward
authors.forename: Caroline J
authors.initials: CJ
authors.lastname: Jolley
authors.forename: Lucy A
authors.initials: LA
authors.lastname: Frank
authors.forename: Caroline
authors.initials: C
authors.lastname: Elston
authors.forename: John
authors.initials: J
authors.lastname: Moxham
authors.forename: Gerrard F
authors.initials: GF
authors.lastname: Rafferty
mesh_terms: D000009:Abdominal Muscles / Q000502:physiology; D000200:Action Potentials / Q000502:physiology; D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology; D003550:Cystic Fibrosis / Q000503:physiopathology*; D003627:Data Interpretation, Statistical; D003964:Diaphragm / Q000502:physiology; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology*; D015656:Respiratory Mechanics / Q000502:physiology; D012132:Respiratory Muscles / Q000503:physiopathology*; D055815:Young Adult