The peroxisome proliferator–activated receptor γ coactivator 1 α (PGC1α) is a major regulator of mitochondrial biology through at least 2 splice variants (5): the canonical longer PGC1α isoform 1 regulates mitochondrial biogenesis and function, whereas the shorter PGC1α isoform 4 (6) increases muscle mass and strength in cachectic muscle (7) and sarcopenia (8). Here, PPARGC1A is linked to sarcopenia.