HIF1AA gene for response to low oxygen

The body uses several proteins to deal with conditions of low oxygen, one of them is HIF1a (coded by the HIF1a gene).  HIF1a controls the activation of genes affecting glucose processing, metabolism, and the formation of red blood cells and blood vessels.  One variant of this gene was found more frequently in weightlifters, while the other was found more frequently in elite endurance athletes and was associated with  a higher increase in VO2 max through aerobic exercise training.