EXERCISE AND OXIDATIVE STRESS - SOURCES OF FREE-RADICALS AND THEIR IMPACT ON ANTIOXIDANT SYSTEMS

Strenuous exercise is characterized by increased oxygen consumption an d the disturbance between intracellular pro-oxidant and antioxidant ho meostasis. At lease three biochemical pathways (i.e., mitochondrial el ectron transport chain, xanthine oxidase, and polymorphoneutrophil) ha ve beers identified as potential sources of intracellular free radical generation during exercise. These deleterious reactive oxygen species pose a serious threat to the cellular antioxidant defense system, suc h as diminished reserves of antioxidant vitamins and glutathione. Howe ver, enzymatic and non-enzymatic antioxidants have demonstrated great versitility and adaptability in response to acute and chronic exercise . The delicate balance between pro-oxidants and antioxidants suggests that supplementation with antioxidants may be desirable for physically active individuals under certain physiological conditions by providin g a larger protective margin.