For isolation of cells for scRNAseq, and in less than 2 hours after collection and preservation in ice-cold hypothermic preservation solution (HypoThermosol® FRS Preservation Solution, H4416 Sigma-Aldrich) , samples were minced in a petri dish on ice using scissors and a surgical blade. Minced samples were transferred into a digestion buffer (4 mL digestion buffer per 100 mg of muscle) containing 2 mg/ml Dispase II (D4693 Sigma-Aldrich) and 2 mg/ml Collagenase IV (17104019 Thermo Fisher Scientific) in HBSS buffer (14025100 Thermo Fisher Scientific) at 37°C for 25-30 minutes, with gentle shaking every 3-5 minutes. After digestion, the reaction was stopped by adding an equal volume of 20% heat inactivated FBS (10500064 Thermo Fisher Scientific) 1mM EDTA (E177 VWR Life Science) in HBSS (14025100 Thermo Fisher Scientific) and the suspension was passed through a 100-µm cell strainer (800100 Bioswisstec) and a 40-µm cell strainer (352340 Falcon). Cell suspension was centrifuged at 500 g for 5 minutes at 4°C and the supernatant discarded. The pellet was resuspended in 1 mL of ACK Lysing Buffer (A1049201 Thermo Fisher Scientific) for red blood cell lysis for 2 minutes at room temperature. After incubation, the reaction was stopped with 4 mL of 10% heat inactivated FBS (10500064 Thermo Fisher Scientific) in HBSS buffer (14025100 Thermo Fisher Scientific). Cell suspension was centrifuged at 500 g for 5 minutes at 4°C and the pellet resuspended in 0.5% BSA (A1391 PanReac AppliChem) in DPBS (14190250 Thermo Fisher Scientific) containing 1mM EDTA (E177 VWR Life Science) for FACS. Calcein Violet (65-0854-39 Thermo Fisher Scientific) was added directly to the cell suspension at 1:1000 dilution 10 minutes before sorting. Metabolically active (Calcein+) human muscle mononuclear cells were FACS sorted and loaded into the 10X Chromium Next GEM Chip G, aiming the recovery of ~10000 cells per sample. scRNAseq libraries were generated according to 10X Chromium Next Gem Single Cell 3' Reagent Kits v3.1 (CG000204 Rev D) and sequenced on the Illumina Novaseq 6000 system