Transgenic expression of catalase in mitochondria using a transgenic strategy extends life span and prevents aging-related pathology in mice. However, transgenic overexpression is not suitable for a clinical application. Adeno-associated virus (AAV) is the most promising gene delivery vehicle. Here we outline strategies on the generation of an AAV vector expressing the mitochondria-targeted catalase gene (AV.RSV.MCAT). We also describe methods for evaluating physiological impact of AV.RSV.MCAT on muscle contractility and running performance in mice.