The effects of aging, physical training, and a single bout of exercise on mitochondrial protein expression in human skeletal muscle

► Regular physical activity attenuates the loss of VO2max in humans. ► Aging decreases the adaptive response of mitochondrial biogenesis. ► Mitochondrial fission is a sensitive marker of the age-associated decline in adaptive response. ► Mitochondrial transcription factor A expression showed a strong relationship with VO2max.