This is a link to an article in The Seattle Times, sent to me by fellow runner Dick Michener:
http://seattletimes.nwsource.com/html/sports/2002551152_boost10.html
It discusses the performance-enhancing drug EPO (erythropoietin). Erythropoietin is a hormone produced by the kidneys that stimulates red blood cell production. We all have natural levels of it in our bodies or else we would all chronically face problems with anemia. People experiencing end-stage renal disease are often given EPO at dialysis as they lack the ability to produce and release adequate amounts of the hormone and, thus, often become anemic.
Below is the standard oxyhemoglobin dissociation curve. The x-axis represents the partial pressure of O2, the form of oxygen we breathe. The y-axis is represented by the percentage of hemoglobin (the molecule on a red blood cell) that is bound to oxygen. The curve demonstrates that the higher the partial pressure of oxygen is, the more oxygen will bind to hemoglobin on a person’s red blood cells. Various conditions may shift this curve – among them is a higher altitude. Increased altitudes lead to a build-up in the bloodstream of 2,3-DPG, which shifts the curve to the RIGHT; that is to say, this results in a DECREASE in hemoglobin’s affinity for oxygen molecules, thus requiring either: A) higher partial pressures of oxygen to force binding between hemoglobin and oxygen, or B) greater production of red blood cells in order to function with a lower percentage of bound oxygen.
(Table can be found at http://www.ventworld.com/resources/oxydisso/dissoc.html )
Therefore:
Higher Altitude –> Increased buildup of 2,3-DPG –> Decreased affinity of hemoglobin for oxygen –> Receptors in body recognize the lack of oxygen saturation –> Stimulates production of erythropoietin –> More red blood cells are produced
What is amazing is that athletes will train at high altitudes as a way of naturally enhancing red blood cell production, and then run races at lower altitudes. At lower altitudes their red blood cells can carry close to a 100% oxygen saturation, PLUS they now have more red blood cells, so they can carry a greater amount of oxygen.
Some athletes, however, have taken to injecting themselves with synthetic erythropoietin in an attempt to achieve the same effect, and the powers that be are not happy with this. So read the article and learn something from it – and about the complications that have arisen as a combined result of human physiology and the desire to be the best.