For succinate dehydrogenase (SDH) staining, slides of muscle biopsies were incubated in SDH staining solution according to a previous report.21 (link) Assessment of lipid content in muscle fibers was done using the lipophilic dye boron-dipyrromethene (BODIPY) 493/503 (790389, Sigma-Aldrich). Slides were mounted with ProLong Gold Antifade Mountant with 4′,6-diamidino-2-phenylindole (DAPI) (P36931, Invitrogen). Histochemical staining was quantified by ImageJ (National Institutes of Health) software.