During physical exercise, cells produce a high level of ROS. While this actually serves a biological role that positively affects skeletal muscle adaptations and force production, in vitro and animal studies suggest that excessively high levels of ROS can contribute to impaired muscle function and muscle fatiguing.[1][2][3]
NAC has been explored as a potential ergogenic due to its antioxidant effects, but research supporting its use is limited. A 2017 meta-analysis was unable to find any evidence of a performance benefit with NAC supplementation, but the analysis included studies using vastly different dosages, exercise regimens, and study populations (e.g., elite athletes, untrained individuals).[4] NAC seems to display the most consistent benefit when exercise is being performed in a fatigued state,[5][6][7] but it may negatively affect muscle adaptations to training.[8] Ultimately, further research is needed to determine if NAC supplementation is beneficial in this context, and if so, in what setting and dosage.
References
- ^Reid MBFree radicals and muscle fatigue: Of ROS, canaries, and the IOC.Free Radic Biol Med.(2008-Jan-15)
- ^Shindoh C, DiMarco A, Thomas A, Manubay P, Supinski GEffect of N-acetylcysteine on diaphragm fatigue.J Appl Physiol (1985).(1990-May)
- ^Reid MB, Haack KE, Franchek KM, Valberg PA, Kobzik L, West MSReactive oxygen in skeletal muscle. I. Intracellular oxidant kinetics and fatigue in vitro.J Appl Physiol (1985).(1992-Nov)
- ^Rhodes K, Braakhuis APerformance and Side Effects of Supplementation with N-Acetylcysteine: A Systematic Review and Meta-Analysis.Sports Med.(2017-Aug)
- ^Cobley JN, McGlory C, Morton JP, Close GLN-Acetylcysteine's attenuation of fatigue after repeated bouts of intermittent exercise: practical implications for tournament situationsInt J Sport Nutr Exerc Metab.(2011 Dec)
- ^Slattery KM, Dascombe B, Wallace LK, Bentley DJ, Coutts AJEffect of N-acetylcysteine on cycling performance after intensified training.Med Sci Sports Exerc.(2014-Jun)
- ^Medved I, Brown MJ, Bjorksten AR, Murphy KT, Petersen AC, Sostaric S, Gong X, McKenna MJN-acetylcysteine enhances muscle cysteine and glutathione availability and attenuates fatigue during prolonged exercise in endurance-trained individualsJ Appl Physiol (1985).(2004 Oct)
- ^Petersen AC, McKenna MJ, Medved I, Murphy KT, Brown MJ, Della Gatta P, Cameron-Smith DInfusion with the antioxidant N-acetylcysteine attenuates early adaptive responses to exercise in human skeletal muscleActa Physiol (Oxf).(2012 Mar)