Although not covering all methodical aspects of a fully grown ICU animal model, studies investigating mitochondrial function by pure immobilization [52,53,54], denervation [47,49,59] or sepsis [79,80] also show deficits in mitochondrial structure and function comparable to observations in critically ill patients, including mitochondrial swelling, decreased mitochondrial content and downregulation of PGC1α mRNA expression as well as several mitochondrial metabolic pathways [81,82,83]. Here, PPARGC1A is linked to Sepsis.