title: Effect of N-acetylcysteine on cycling performance after intensified training.
abstract: OBJECTIVE
  This investigation examined the ergogenic effect of short-term oral N-acetylcysteine (NAC) supplementation and the associated changes in redox balance and inflammation during intense training.
  
  
  METHODS
  A double-blind randomized placebo-controlled crossover design was used to assess 9 d of oral NAC supplementation (1200 mg·d) in 10 well-trained triathletes. For each supplement trial (NAC and placebo), baseline venous blood and urine samples were taken, and a presupplementation cycle ergometer race simulation was performed. After the loading period, further samples were collected preexercise, postexercise, and 2 and 24 h after the postsupplementation cycle ergometer race simulation. Changes in total antioxidant capacity, ferric reducing ability of plasma, reduced glutathione, oxidized glutathione, thiobarbituric acid-reactive substances, interleukin 6, xanthine oxidase, hypoxanthine, monocyte chemotactic protein 1, nuclear factor κB, and urinary 15-isoprostane F2t concentration were assessed. The experimental procedure was repeated with the remaining supplement after a 3-wk washout. Eight participants completed both supplementation trials.
  
  
  RESULTS
  NAC improved sprint performance during the cycle ergometer race simulation (P < 0.001, ηp = 0.03). Supplementation with NAC also augmented postexercise plasma total antioxidant capacity (P = 0.005, ηp = 0.19), reduced exercise-induced oxidative damage (plasma thiobarbituric acid-reactive substances, P = 0.002, ηp = 0.22; urinary 15-isoprostane F2t concentration, P = 0.010, ηp = 0.431), attenuated inflammation (plasma interleukin 6, P = 0.002, ηp = 0.22; monocyte chemotactic protein 1, P = 0.012, ηp = 0.17), and increased postexercise nuclear factor κB activity (P < 0.001, ηp = 0.21).
  
  
  CONCLUSIONS
  Oral NAC supplementation improved cycling performance via an improved redox balance and promoted adaptive processes in well-trained athletes undergoing strenuous physical training.
authors.affiliation: 1Sport and Exercise Discipline Group, Faculty of Health, University of Technology, Sydney, AUSTRALIA; 2Applied Sports Science and Exercise Testing Laboratory, School of Environmental and Life Sciences, University of Newcastle, Callaghan, AUSTRALIA; and 3Human Exercise Performance Laboratory, School of Medical Science, University of Adelaide, Adelaide, AUSTRALIA.
authors.forename: Katie May
authors.initials: KM
authors.lastname: Slattery
authors.forename: Ben
authors.initials: B
authors.lastname: Dascombe
authors.forename: Lee Kenneth
authors.initials: LK
authors.lastname: Wallace
authors.forename: David J
authors.initials: DJ
authors.lastname: Bentley
authors.forename: Aaron James
authors.initials: AJ
authors.lastname: Coutts
mesh_terms: D000111:Acetylcysteine / Q000008:administration & dosage*; D000975:Antioxidants / Q000008:administration & dosage*; D001642:Bicycling / Q000502:physiology*; D018592:Cross-Over Studies; D019587:Dietary Supplements; D004311:Double-Blind Method; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010806:Physical Education and Training; D010807:Physical Endurance / Q000502:physiology*
chemical_list: D000975:Antioxidants; D000111:Acetylcysteine