Blood doping
Blood doping is the practice of boosting the number of red blood cells in the bloodstream in order to enhance athletic performance. Because such blood cells carry oxygen from the lungs to the muscles, a higher concentration in the blood can improve an athlete’s aerobic capacity (VO2 max) and endurance. Many methods of blood doping are illegal, particularly in professional sports.
Blood doping is defined as the use of illicit products (i.e. erythropoietin (EPO), darbepoetin-alfa, hypoxia-inducible factor (HIF) stabilizers) and methods (i.e. increase aerobic capacity by maximizing the uptake of O2) in order to enhance the O2 transport of the body to the muscles.
The body undergoes aerobic respiration in order to provide sufficient delivery of O2 to the exercising skeletal muscles and the main determining factors are shown in figure 1. The rate maximum O2 uptake (O2max) depends on cardiac output, O2 extraction and hemoglobin mass. The cardiac output of an athlete is difficult to manipulate during competitions and the distribution of cardiac output is at the maximum rate (i.e. 80%) during competitions. In addition, the O2 extraction is approximately 90% at maximal exercise. Therefore, the only method to enhance the physical performance left is to increase the O2 content in the artery by enhancing the hemoglobin mass. In other words, hemoglobin concentration and blood volume contribute to hemoglobin mass.
Many forms of blood doping stem from the misuse of pharmaceuticals. These drug treatments have been created for clinical use to increase the oxygen delivery when the human body is not able to do so naturally.
Erythropoietin is a glycoprotein hormone produced by the interstitial fibroblasts in the kidney that signal for erythropoiesis in bone marrow.(Britannica) The increased activity of a Hemocytoblast (RBC stem cell) allows the blood to have a greater carrying capacity for oxygen. EPO was first developed to counteract the effects of chemotherapy and radiation therapy for cancer patients. EPO also stimulates increased wound healing. The physiological side effect of EPO, particularly increased hematocrit, has become a potential drug to abuse by professional and amateur cyclists.
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