Sarcopenia is age-associated deterioration of muscle mass and function caused by a wide scope of physiological and pathological changes ranging from hormonal disorders to loss of subcellular homeostasis. Recent research indicates that mitochondrial dysregulation with advanced age plays a central role in the development of sarcopenia due to the multifactorial functions of this organelle in energy supply, redox regulation, crosstalk with nuclear gene expression and apoptosis. In order to fulfill these roles, it is crucial that mitochondria maintain their own structural and functional integrity through biogenesis, antioxidant defense, fusion/fission dynamics and autophagy (mitophagy). Unfortunately, mitochondria undergo age-associated changes that compromise the above-mentioned properties that eventually contribute to the development of sarcopenia. The peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is involved in the transcriptional regulation of numerous nuclear and mitochondrial gene products participating in the cellular events that control muscle mass and function. Thus, it is not surprising that maintaining an optimal intracellular PGC-1α level and signaling activity is crucial in protecting the muscle from many degradative and destructive processes, such as proteolysis, oxidative damage, inflammation, uncontrolled autophagy and apoptosis. Physical exercise is a powerful stimulus to PGC-1α expression and signaling. Recent research indicates that PGC-1α-controlled mitochondrial biogenesis is not limited by old age per se and that elderly individuals can still benefit from increased muscular activity in terms of skeletal muscle health that ultimately contributes to quality of life in old age.