Exercising muscle need a continual supply of O2 for generating energy to sustain endurance activities Blooddoping is a technique used to temporarily increase the O2-carrying capacity of blood in an attempt to gain a competitive advantage. Blood doping involves removing blood from an athlete, then promptly reinfusing the plasma but freezing the RBCs (Red Blood Cells) for reinfusion one to seven days before a competitive event. One to four units of blood (one unit equals 450 mL) are usually withdrawn at three- to eight-week intervals before the competition. In the periods between blood withdrawals, increased erythropoietin activity restores the RBC count to normal. Reinfusion of the stored RBCs artifcially increases the RBC count and hemoglobin level above normal before competing. Theoretically, blood doping would beneft endurance athletes by improving the blood’s O2-carrying capacity. If too many red cells were infused, however, performance could suffer because the increased blood viscosity would decrease blood flow.
Research indicates that athletes who have used blood doping may realize a 5% to 13% increase in aerobic capacity; a reduction in heart rate during exercise compared to the rate during the same exercise in the absence of blood doping; improved performance; and reduced lactate levels in the blood. (Lactate is produced when muscles resort to less effcient anaerobic glycolysis for energy production.
Blood doping, although effective, is illegal in collegiate athletics and Olympic competition for ethical and medical reasons. Of concern, as with use of any banned performance-enhancing product, is loss of fair competition. Furthermore, the practice can lead to high blood pressure and has been implicated in the deaths of some athletes. The development of synthetic erythropoietin (EPO) exacerbates the problem of blood doping. Injection of this product stimulates RBC production and thus temporarily increases the O2-carrying capacity of the blood. Injected EPO may improve an endurance athlete’s performance by 7% to 10%. Although formally banned, a black market for EPO developed among sports cheats when this product became available as a drug to treat anemia. Erythropoietin is now widely used among competitors in cycling, cross-country skiing, and long-distance running and swimming. This practice is ill advised, however, not only because of legal and ethical implications, but also because of the dangers of increasing blood viscosity. Synthetic EPO is believed responsible for the deaths of a number of cyclists. Unfortunately, too many athletes
are willing to take the risks. It is hoped that recent development of tests to detect blood doping and illegal erythropoietin use, coupled with recent public scorn and medal stripping related to their abuse, will curb their use in the future
Source: Human Physiology. Sherwood