Aging is associated with a reduced ability to buffer oxidants along with an increase in oxidant production, resulting in chronic oxidative stress. Oxidative stress is a putative factor responsible for reducing function ability of skeletal muscle and increasing oxidative damage. The objective of this set of investigations was to evaluate the efficacy of reducing oxidative stress on improving muscle function the adaptive response of skeletal muscle to repetitive loading exercise in aging rodents. To achieve this objective, three methods of reducing oxidative stress were utilized; the antioxidant vitamins E&C were used to buffer oxidants, the nutraceutical resveratrol was used to inhibit oxidant production and the pharmacological agent allopurinol was used to attenuate oxidant production specifically through the inhibition of xanthine oxidase activity. This set of investigations show evidence that muscles from aged animals have high basal levels of xanthine oxidase, and this is further exacerbated by resistance exercise. Antioxidant treatment in aged rodents will reduce oxidative stress associated with both aging and exercise. Furthermore, an increase in xanthine oxidase activity is a major contributor to the oxidative stress associated with resistance exercise (i.e. repetitive loading). Modulation of exercise-induced oxidative stress will effect adaptation of the endogenous antioxidant system and different therapeutic methods of reducing oxidative stress in aged muscle produce slightly different results in muscle function. The results suggest that resistance training increases xanthine oxidase activity, which contributes to exercise-induced oxidative stress in muscles of aged mice. Furthermore, resistance exercise invokes a distinctive response in the endogenous antioxidant enzymes that differ from that typically observed with aerobic exercise
