Mitochondrial dysfunction is central to skeletal muscle dysfunction. Skeletal muscle mitochondria are necessary for the efficient generation of energy (ATP) from oxygen and normal lipid metabolism. Under normal conditions, muscle efficiently utilizes the majority of supplied oxygen such that only 0.2% of mitochondrial oxygen is shuttled into reactive oxidative species (ROS). Under pathologic situations there is uncoupling of oxygen consumption and ATP generation resulting in increased oxygen consumption and decreased ATP production in a process leading to increased ROS and oxidative stress. Uncoupling of oxygen and ATP generation directly affects skeletal muscle function. Decreased efficiency of ATP generation has been linked to decreased muscle strength and more recently associated with decreased gait speed in older adults.