Is iron the answer to training at altitude?
By Erin Beresini, Outside
Athletes live and sometimes train at high altitude for one main reason: it stimulates erythropoiesis, or the production of red blood cells and hemoglobin, the protein inside red blood cells that carries oxygen around the body.
That extra hemoglobin should bring more oxygen to muscles, which should lead to improved muscle function and endurance when an athlete competes at a lower altitude soon after leaving the mountains.
The problem is, individual athletes respond differently to altitude. Even after the generally recommended four weeks of living between about 5,200 to 9,800 feet, some athletes won’t show much increase in hemoglobin. That’s why researchers have begun experimenting with iron supplementation.