Levels of mRNA expression of factors regulating skeletal muscle oxidative capacity i.e. , peroxisome proliferator-activated receptor gamma coactivator-1 ( PGC-1alpha ) and vascular endothelial growth factor ( VEGF ) , and glycolytic capacity , i.e. , phosphofructokinase ( PFK ) , glycogen phosphorylase and synthase , hexokinase , and phosphorylase kinase alpha1 , were subsequently analyzed .