Gene expression of hypoxia-inducible factor 1 alpha , cytochrome c oxidase subunit 4 , peroxisome proliferator-activated receptor gamma coactivator 1 alpha , hexokinase , phosphofructokinase , mitochondrial fission 1 , and mitofusin-2 increased with exercise ( P < .05 ) but did not differ with hypoxic exposure ( P > .05 ) .