Sports Fitness Training

It is well known that intense or prolonged exercise results in oxidative injury to skeletal muscles, particularly in untrained individuals. Further, there is growing evidence that radicals and other reactive oxygen species contribute to muscular fatigue. Therefore, it is not surprising that there is strong interest in the effects of antioxidant supplements on exercise performance. Numerous animal studies have examined the effects of antioxidants on muscular performance. Many of these experiments have used in vitro preparations in which antioxidants were added to the bathing medium surrounding the muscle. In general, these in vitro experiments indicate that the addition of antioxidants results in delayed muscular fatigue. Some in vivo animal studies also indicate that the addition of antioxidants can improve muscular performance. Collectively, these experiments suggest that antioxidant supplementation can improve muscular performance by reducing exercise-induced oxidative stress. Nonetheless, most animal studies have used antioxidant treatments that cannot be used in humans. Therefore, results from antioxidant research using animal models cannot always be directly extrapolated to humans.Research examining the effects of antioxidant supplementation on human performance is in its infancy. At present, limited studies have examined the effects of antioxidant supplementation on muscular endurance in humans. Further, many of the studies suffer experimental design weaknesses and most studies have investigated the effects of a single antioxidant rather than investigating the combined effects of both lipid and water-soluble antioxidants. By far, the most widely studied antioxidant vitamin is vitamin E, whereas few studies have examined the effects of other antioxidants on human performance. Although several human studies have indicated that supplementation with vitamin E and/or vitamin C reduce exercise-induced oxidative stress, there is limited evidence that antioxidant supplementation can improve human performance. However, because of the paucity of research on this topic, many additional studies are required before a firm conclusion can be reached about the effects of antioxidant treatment on human exercise tolerance.

Future studies should examine the potential synergistic effects of several antioxidants on human performance. Further, additional experiments are required to explore the bioavailability of nutritional antioxidants provided in tablet form compared to the bioavailability of these nutrients derived from whole food. This is an interesting area for future research.