Free radicals, also commonly known as reactive oxygen species (ROS), are molecules that contain one or more unpaired electrons in their outer orbit. ROS are unstable in this state and, in an effort to become more stable, can react with other molecules. Therefore, ROS are harmful in that they can damage the functional capacity of these other molecules, such as cell membranes, DNA and proteins. In fact, ROS has been linked with cardiovascular disease, various forms of cancer and aging. Moreover, it is also recognized that ROS production occurs from numerous metabolic processes, including exercise. Because of the link between cell damage and ROS, conventional wisdom has been that antioxidant supplementation may benefit exercise performance and enhance recovery by countering the increase in ROS associated with exercise.