As a result of training, all of the various oxidative processes are elevated in both aerobic and anaerobic athletes. The magnitude of these elevations depends on the intensity and type of exercise in which one is engaged. Also, some authors have speculated that the oxidative muscle damage associated with exercise may lead to the termination of muscular effort. In light of this knowledge, researchers and lay people alike have speculated that antioxidant supplementation may level the playing field, reducing tissue damage and soreness, improving exercise performance, and even prolonging life span. But do we need nutritional supplements to protect us from oxidative damage Or can our bodies handle the stress naturally through homeostasis?

Regarding antioxidant homeostasis, most of the research done on endogenous antioxidant enzymes and their adaptation to exercise has been done using endurance protocols. From this research, aerobically trained individuals (including humans and rats) have elevated endogenous (produced within) antioxidant enzyme concentrations and/or activities compared with controls As the body adapts to the demands of an increased training load by increasing mitochondrial density, capillarization, stroke volume of the heart, etc., it also defends itself from the increasing amount of oxygen that is delivered and used by the muscle. Because mitochondrial density increases (there are more mitochondria per unit of muscle) in aerobically trained individuals and the antioxidant enzymes are located within the mitochondria, it only stands to reason that antioxidant activity would increase in endurance-trained individuals. Of course, the more mitochondria, the more potential for reactive oxygen species, so the question is whether the increased enzymes can deal with the increased free radicals.

In numerous studies, the activities of the enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPX) were increased in oxidative (type 1) skeletal muscle with endurance training. In addition, glutathione levels increase in response to training while oxidative damage is lessened when compared to untrained rats and humans. Although this suggests that trained individuals have a better protection from exercise-induced free radical damage than untrained, it cannot be assumed that the skeletal muscle of these individuals has enzyme levels that completely protect against free radical damage. Nor is it safe to assume that all athletes gain the same degree of antioxidant protection from training. Since enzymatic adaptations occur primarily in slow-twitch muscle fiber sand fast-twitch fibers do not, to a large extent, undergo such changes, athletes with a higher percentage of fast-twitch fibers like bodybuilders, sprinters, and power lifters may be more susceptible to free radical damage

The knowledge of training-induced endogenous antioxidant up regulation does, in fact, question the need for endogenous antioxidant supplementation. That is, why do athletes need an antioxidant boost when the body naturally adapts to exercise by improving its defenses Although the antioxidant capacity of the body is increased with endurance training, it appears that even these increases are often not sufficient to neutralize the increase in free radicals generated from long-duration aerobic exercise. It is clear that, depending on the type of exercise, free radical formation may supercede the body’s ability to protect itself, even in training-adapted individuals. In this case, it would be appropriate to increase the ingestion of exogenous antioxidants.

That said, the next relevant question would address whether the ingestion of foods that are high in bioavailable antioxidants would be sufficient to provide for the additional needs of specific populations or whether further antioxidant intake would be necessary. Since intense exercise training leads to the depletion of tissue and plasma concentrations of antioxidants such as coenzyme Q10 or ubiquinone, vitamin C, and vitamin E, this reduction may lead to a decreased antioxidant defense. This depletion is evident even in those athletes consuming a “nutritious, well-balanced, and mixed diet.” Hence, dietary intake may not provide sufficient amounts of antioxidants to athletes. By increasing tissue and plasma concentrations via antioxidant supplementation, athletes can assist endogenous antioxidant capacity and complement dietary intake to reduce the damage that results from strenuous training. Granted, antioxidants and nutrients seem to be better absorbed and seem to confer greater benefit when consumed as part of whole foods, but when whole food intake is insufficient, additional supplementation is the next best thing.