PDK4 and amyotrophic lateral sclerosis: This switch in fiber type observed at the cellular level is accompanied by increased expression of metabolic markers known to promote or participate in oxidative metabolism under physiological condition or in an ALS context such as Pgc1α, Pparα, Pparδ, Pdk4, or Lcad [11,14,18,79], as well as the rise of mRNA encoding important component of the electron transport chain (Sdha, Uqcrc2, and Cox5A) supporting a higher mitochondrial activity.