Summary: In this Administrative Supplement we are requesting support to repeat an major experiment described under the parent grant: “Interplay between lipophagy and mitophagy in skeletal muscle aging” (5R01AG020866). In this experiment, old and young (female and male C57BL/6J mice) will be used to isolate mononuclear cells which then will be analyzed by mass cytometry to explore, at the single cell level, changes in autophagy flux in each cell type. The original experiment could not be completed successfully due to logistical operations brought up by the Covid-19 pandemic.