With the premise that U.S. Veteran demographics reveal an aging population with significant mobility limitation and oxidative stress is tightly linked to both of these characteristics, a series of skeletal muscle/vascular studies are proposed. Specifically, in a series of recent studies the investigators' group has documented positive vascular consequences of antioxidant supplementation during exercise in older subjects that negatively impacted young people. Further provocative findings revealed that following exercise training the older subjects were now also negatively impacted by the antioxidant supplementation. These findings have implications for the understanding of the complex balance between the positive effects of exercise-based rehabilitation, exercise induced oxidative stress, aging, frailty, and subsequent mobility limitation. Therefore four specific aims are proposed that will answer the questions of where (I) oxidative stress is most prevalent in the elderly, why (II) oxidative stress occurs in the elderly, what (III) are the acute consequences of oxidative stress in the elderly, and finally how (IV) can exercise-induced oxidative stress as the result of exercise training in elderly be appropriately managed with exogenous antioxidant therapy to promote compliance and the positive outcome of increased mobility.