The response by Marcinek and Ferrucci to Lanza et al. addresses the impact of age on mitochondrial function and physical activity in aged skeletal muscles. They emphasize the need for large datasets to account for various factors affecting oxidative capacity, highlighting the intrinsic effect of age on mitochondrial energetics. The study underscores the importance of tailored exercise prescriptions for older adults to maintain mitochondrial function and overall health, advocating for the consideration of age and physical activity in all studies of mitochondrial function.