title: Effects of N-acetylcysteine on respiratory muscle fatigue during heavy exercise.
abstract: Respiratory muscle fatigue (RMF) occurs during heavy exercise in humans. N-acetylcysteine (NAC) infusion has been shown to reduce RMF, suggesting that oxidative stress is a contributing factor. The purpose of the present study was to determine the effect of an acute oral dose of NAC on RMF during heavy exercise. Subjects (n=8) were given either placebo (PLA) or NAC (1,800 mg) 45 min prior to a 30 min constant load (85V(O)(2peak)), discontinuous exercise test. Maximum respiratory pressures (inspiratory, PI(max); expiratory, PE(max)) and venous blood samples were made prior to and following each 5 min of exercise. There was no difference (p>0.05) in PI(max) between NAC (127.9+/-34.1 cm H(2)O) or PLA (134.1+/-28.1cm H(2)O) at rest. During exercise, PI(max) was significantly lower with PLA ( approximately 14%) compared to NAC at 25 and 30 min suggesting less RMF with NAC. There were no differences (p>0.05) between groups in PE(max), V(O)(2), V(E), or heart rate at rest or throughout exercise. These results suggest that an acute dose of NAC reduces RMF during heavy exercise.
authors.affiliation: Department of Kinesiology, Kansas State University, 1A Natatorium, Manhattan, KS 66506, United States.
authors.forename: Megan K
authors.initials: MK
authors.lastname: Kelly
authors.forename: Reneé J
authors.initials: RJ
authors.lastname: Wicker
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Barstow
authors.forename: Craig A
authors.initials: CA
authors.lastname: Harms
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology*; D000328:Adult; D000704:Analysis of Variance; D018592:Cross-Over Studies; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D016166:Free Radical Scavengers / Q000494:pharmacology*; D005978:Glutathione / Q000097:blood; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000187:drug effects* / Q000502:physiology; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D010807:Physical Endurance / Q000187:drug effects / Q000502:physiology; D012119:Respiration / Q000187:drug effects; D012129:Respiratory Function Tests / Q000379:methods; D012132:Respiratory Muscles / Q000187:drug effects*; D055815:Young Adult
chemical_list: D016166:Free Radical Scavengers; D005978:Glutathione; D000111:Acetylcysteine