Exercise training-induced alterations in skeletal muscle antioxidant capacity: a brief review

Cellular oxidants include a variety of reactive oxygen, nitrogen, and chlor inating species. It is well established that the increase in metabolic rate in skeletal muscle during contractile activity results in an increased pro duction of oxidants. Failure to remove these oxidants during exercise can r esult in significant oxidative damage of cellular biomolecules. Fortunately , regular endurance exercise results in adaptations in the skeletal muscle antioxidant capacity, which protects myocytes against the deleterious effec ts of oxidants and prevents extensive cellular damage. This review discusse s the effects of chronic exercise on the up-regulation of both antioxidant enzymes and the glutathione antioxidant defense system. Primary antioxidant enzymes superoxide dismutase, glutathione peroxidase, and catalase will be discussed as well as glutathione, which is an important nonenzymatic antio xidant. Growing evidence indicates that exercise training results in an ele vation in the activities of both superoxide dismutase and glutathione perox idase along with increased cellular concentrations of glutathione in skelet al muscles. It seems plausible that increased cellular concentrations of th ese antioxidants will reduce the risk of cellular injury, improve performan ce, and delay muscle fatigue.