Mice carrying a homozygous proof-reading deficient version of the mtDNA polymerase gene Polg are characterized by a reduced life span, with a maximum survival of 15 months, and all Polg mice display progeroid features such as kyphosis and sarcopenia that become apparent from the age of 9 months (Trifunovic et al., 2004; Kujoth et al., 2005; Shabalina et al., 2017). Here, POLG is linked to sarcopenia.