Living in an oxygen-rich environment presents an enigma for principally aerobic organisms such as human beings. Oxygen is an absolute requirement for life, yet paradoxically it also contributes to an “erosion” of the organism over time as metabolism continues. Derivatives of oxygen known as reactive oxygen species (ROS) have been implicated in a number of pathological conditions including cancer, myocardial infarction, inflammatory diseases, and diseases of aging. A listing of the most prevalent reactive oxygen species implicated in such conditions is given in. Interestingly, although reactive oxygen species and radicals are implicated in numerous disease states, their presence in small amounts can also be beneficial.Reactive oxygen species lead to the formation of free radicals, which are atoms or groups of atoms that contain one or more unpaired electrons. Without belaboring this description, atoms with unpaired electrons are extremely volatile and can react with cellular components such as proteins (both enzymatic and structural), membrane lipids, and the nucleotides within DNA and RNA. This places every part of the cell at risk for radical-induced damage. Fortunately, however, humans have well-developed enzymatic and nutritional defenses to protect against such toxic oxygen species . These defense mechanisms help to maintain a favorable pro-oxidant to antioxidant balance and prevent cellular damage. Some conditions, however, such as hypoxia, severe heat stress, septic shock, stretch-induced injury, and intense physical exercise can overwhelm these defenses and lead to an unfavorable balance in which pro-oxidation and cell damage predominate.
Both intense resistance and aerobic exercise have been shown to increase the production of reactive oxygen species and free radicals. Although the mechanisms by which this occurs are still under investigation, three main free radical-producing processes are of special concern to individuals who exercise. These three mechanisms are accelerated metabolic (mostly mitochondrial) oxygen processing, ischemic-reperfusion injury, and muscle micro trauma/repair (leukocyte radical production). Accelerated mitochondrial oxygen processing is most associated with endurance training whereas ischemicÂreperfusion injury and muscle repair are associated with resistance training. Currently, there is considerable debate as to whether these processes are adaptive and beneficial or whether they are pathological and harmful. Regardless, the impact of free radical production remains the same. Exercise-induced free radical production and damage is capable not only of slowing recovery from strenuous exercise, but also of causing damage to a variety of tissues and organs.
Tags:aerobic exercise, aerobic organisms, Antioxidant Supplementation, cellular damage, defense mechanisms, dna and rna, enzymatic, hypoxia, inflammatory diseases, intense physical exercise myocardial infarction
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