HIF1A and Obesity: One possible mechanism explaining impaired regeneration of skeletal muscle in models of obesity is the involvement of the prolyl hydroxylase (PHD) domain family of enzymes that regulate vascular endothelial growth factor (VEGF) expression and hypoxia-inducible factor-1 alpha (HIF-1α) (Matsuura et al., 2013; Michailidou et al., 2015).