Antioxidant Supplements and Exercise Adaptations

Antioxidant supplements (e.g., vitamin C) are widely used by athletes and recreational exercisers in an attempt to limit the potentially deleterious effects of exercise-induced reactive oxygen species (ROS) and reactive nitrogen species (RNS) on performance, recovery, and health. Despite evidence to support beneficial effects of some antioxidant compounds in certain contexts, growing evidence suggests that antioxidant supplements do not provide clear benefit for athletes and some may in fact hamper normal exercise-related cellular and physiological adaptations due to their interference with normal adaptive redox-signaling pathways. In this chapter, we review the use and effects of exogenous antioxidants in the context of exercise-related adaptations including mitochondrial biogenesis, antioxidant enzyme expression, vascular function, muscle hypertrophy and strength, substrate metabolism, and exercise performance enhancement. Effects of specific antioxidant compounds on these outcomes depend on their in vivo mechanisms of action and interactions with endogenous antioxidant systems, their dose, their bioavailability, and the regimen of their administration used. Effectiveness of antioxidants may also depend on interindividual factors, such as whether an antioxidant deficiency exists and whether the antioxidant treatment can restore that deficiency. An individualized approach to antioxidant supplementation that considers these factors may be required for an antioxidant treatment strategy to be effective for athletes and exercisers. In this chapter, the authors review the use and effects of exogenous antioxidants in the context of exercise-related adaptations including mitochondrial biogenesis, antioxidant enzyme expression, vascular function, muscle hypertrophy and strength, substrate metabolism, and exercise performance enhancement. They discuss the evidence from studies of antioxidant supplementation and its effects on physiological responses and adaptations to exercise. The authors explore the impact of exogenous antioxidants on exercise training adaptations including mitochondrial biogenesis, antioxidant enzyme induction, vascular function, muscle hypertrophy and strength, substrate metabolism, and exercise performance enhancement. Mitochondria are the primary hub of cellular metabolism and highly abundant in tissues such as skeletal muscle. Overall, it is clear that antioxidant supplements are not a one-stop-shop solution for improving exercise training