INS and metabolic syndrome: These mechanisms include age-related reductions in protein synthesis and increased proteolysis, fat infiltration into skeletal muscle promoting lipotoxicity and aggravating inflammation, mitochondrial dysfunction, oxidative stress [22,23,24], and metabolic abnormalities such as insulin resistance (IR), which is commonly defined as diminished sensitivity or receptivity to the metabolic actions of insulin and is a risk factor for metabolic syndrome (MetS) and type 2 diabetes [25,26].