Exercise causes an increase in the generation of
reactive oxygen species (ROS)
that if not balanced appropriately by antioxidant defense systems contributes to fatigue and impaired physiologic responses to training. Cysteine and thiol groups are rate-limiting for synthesis of
, one of the most important antioxidant defense systems in cells. Suboptimal cellular levels of GSH contributes to excessive oxidative stress that can amplify the biochemical stress response to exercise and impair recovery. Increased GSH translates into better anti-oxidant capacity, reduced oxidative stress and increased exercise performance. Adequate cysteine and GSH are also linked with protein metabolism either through better maintenance of protein synthesis or reduced protein catabolism.
is a form of cysteine that is more efficiently absorbed and used by the body. Another less appreciated supplement with antioxidant potential is
. Previous work has shown positive effects of lipoic acid as a powerful antioxidant, and in addition other work has shown lipoic acid decreased food intake, increased energy expenditure, decreased body weight and body fat. In a recent study, Polish researchers tested the effects of both NAC and lipoic acid supplementation on a broad spectrum of oxidative stress markers. Trained athletes consumed either 1200 mg/day of NAC, 600 mg lipoic acid, or Placebo for 8 days. Both supplements significantly elevated plasma total antioxidant status and reduced protein carbonylation and lipid peroxidation by an average of nearly one-third.
also improved glutathione antioxidant status. These findings confirm both NAC and lipoic acid are antioxidants and specifically enhance antioxidant capacity in athletes.
Zembron-Lacny A, Slowinska-Lisowska M, Szygula Z, Witkowski K, Szyszka K. The comparison of antioxidant and haematological properties of N-acetylcysteine and alpha-lipoic acid in physically active males. Physiol Res. 2008 Dec 17. [Epub ahead of print]