What is the effect of antioxidant supplementation on exercise performance?
We know that free radicals are produced during normal cellular metabolism. Radicals damage the cells by reacting with cellular components. This damage is called oxidation and can result in an inflammatory response to the cell and subsequent damage. The antioxidants within the cell work to neutralize these free radicals circulating through our bodies.
There are two major classes of antioxidants that work together in cells to reduce the harmful effects of radicals: 1) enzymatic and 2) non-enzymatic antioxidants.
· Enzymatic Antioxidants - Key antioxidant enzymes include superoxide dismutase, glutathione peroxidase, and catalase. These enzymes are manufactured in the cell and cannot be obtained through dietary supplementation.
· Non-Enzymatic Antioxidants - Important non-enzymatic antioxidants include vitamins E and C, and b-carotene. These antioxidants are included in many foods and can also be obtained through dietary supplements. Vitamins E and b-carotene protect cell membranes from radical damage. Vitamin C works in conjunction vitamin E to protect both fatty substances and proteins in the cell from radical damage.
Exercise has its benefits but it also causes an increased production of free radicals. Prolonged exercise such as marathon running can cause oxidation with subsequent injury to skeletal muscles, particularly in untrained individuals. This process also contributes to muscular fatigue during endurance events.
Reid and colleagues in the Journal of Clinical Investigation (1994; vol.6, p. 2468) reported that N-acetylcysteine pretreatment could improve performance of human limb muscle during fatiguing exercise. They suggested that oxidative stress played a causal role in the fatigue process and identified antioxidant therapy as an intervention clinically.
Chandan presented information on glutathione in response to exercise training in the 1999 journal of Molecular and Cellular Biochemistry (vole 196, #1-2). He stated that “skeletal muscle GSH (glutathione) appears to be tightly regulated by the state of physical activity. N-acetyl-L-cysteine (NAC) and alpha lipoic acid (LA) are two antioxidant dietary supplements that are able to enhance cellular GSH levels.” He reported that both NAC and LA had beneficial effects in protecting against exercise induced oxidative stress.
We know that prolonged and/or intense exercise produces free radicals. Is there a role for antioxidant supplement?
It certainly appears then that appropriate training programs and nutritional interventions are potential strategies to enhance fatigue resistance and exercise performance. A well balanced diet of fruits and vegetables is certainly in order. The use of enzymatic antioxidant supplements can be considered to support the training athlete because they work at the cellular level.
As always consultation with the appropriate health care provider is advised.
