Taking a step back, although increased oxygen processing and subsequent radical production seem to be the ultimate villains to exercising individuals, this is not necessarily the case. It’s not news to anyone that people need oxygen to survive. This fact is made obvious by traveling to a high altitude, where symptoms quickly arise largely because of the lack of oxygen in the local environment. In an effort to get the oxygen it desperately needs, the body starts adapting to the low-oxygen (hypoxic) conditions immediately.
By making more red blood cells (i.e., erythropoiesis) to carry oxygen and by better processing what little oxygen is there, the body starts to look more aerobically oriented-a situation that is advantageous to endurance athletes upon returning to lower elevations.
But oxygen is not just for producing physical work; it is also a vital process for combusting our food at rest, supplying energy for numerous metabolic processes and producing body heat. Once again, human beings are principally aerobic animals, even if some choose to focus on primarily anaerobic sports, like weight trainers do.
Furthermore, processes such as lipid peroxidation (cell membrane oxidation by free radicals) are not uniformly pathologic either. This process of breaking down lipids in the cell membrane is one way that the membrane renews itself. In addition, lipid peroxidation can form necessary mediators of inflammation and immune function.
Even the leukocyte oxidative burst that occurs as a result of cell damage or foreign invaders is part of antigen defense and a necessary clean-up step that precedes new tissue growth (hypertrophy). It is primarily when the prooxidant-antioxidant ratio becomes elevated that a detrimental sequelae of events occur, damaging structures like cell and mitochondrial membranes and nuclear material.
Chronic elevation of this ratio has, indeed, been implicated in a variety of disease states. Thus, although excessive amounts of cell oxidation can be detrimental, without some oxidation humans could not survive. It seems then that one of the nutritional goals of athletes should be to limit the deleterious effects of accelerated oxidation without affecting oxidative processes critical to health and performance. In other words, athletes should seek to find the ideal antioxidant balance.