MSTN and sarcopenia: Sarcopenia has been associated with several processes, including oxidative stress, mitochondrial dysfunction, senescent satellite cell accumulation, protein homeostasis imbalance, inappropriate diet, NAD+ deterioration, increased myostatin and GDF-15, immunosenescence, gut microbiota alteration, and hormonal deviations [29,30,39,40,41,42,43] (Figure 3).