N-acetylcysteine infusion alters blood redox status but not time to fatigue during intense exercise in humans

1 Muscle, Ions, and Exercise Group, Centre for Rehabilitation, Exercise, and Sport Science, School of Human Movement, Recreation, & Performance, Victoria University of Technology, 2 Department of Anaesthesia, Austin and Repatriation Medical Centre, and 3 Department of Anaesthesia and Pain Management, Royal Melbourne Hospital, Melbourne, Victoria, Australia 8001 Infusion of the antioxidant N -acetylcysteine (NAC) reduces fatigability in electrically evoked human muscle contraction, but due to reported adverse reactions, no studies have investigated NAC infusion effects during voluntary exercise in humans. We investigated whether a modified NAC-infusion protocol (125 mg · kg 1 · h 1 for 15 min, then 25 mg · kg 1 · h 1 ) altered blood redox status and enhanced performance during intense, intermittent exercise. Eight untrained men participated in a counterbalanced, double-blind, crossover study in which they received NAC or saline (control) before and during cycling exercise, which comprised three 45-s bouts and a fourth bout that continued to fatigue, at 130% peak oxygen consumption. Arterialized venous blood was analyzed for glutathione status, hematology, and plasma electrolytes. NAC infusion induced no severe adverse reactions. Exercise decreased the reduced glutathione ( P