Just as Roman gladiators drank the blood of foes to gain strength, modem Ol

游客2024-10-12 51

问题    Just as Roman gladiators drank the blood of foes to gain strength, modem Olympians have infused the blood of their own to gain endurance. Blood doping, which tainted the triumphs of some Olympians, has at last been banned.
   Blood doping, in short, means withdrawal of one unit of a little more of blood from an athlete’s system about four to six weeks before a competition. The blood is then stored in a frozen state while the body replenished the lost blood through natural processes. The extracted blood is unfrozen and then pumped back into the athlete’s system just before the competition. This increases the body’s hemoglobin count, hereby increasing the capacity for oxygen delivery and raising the level of endurance.
   A recent colloquium on the ethics of blood doping, summarized in The Physician and Sports Medicine, cited eases of runners getting blood transfusions so they could run fast enough to qualify for Boston Marathon and of blood doping in dog and horse racing.
   Blood doping may be surprisingly common among world-class endurance athletes, especially cyclists and runners. Blood doping is cheating and it is now banned by the International Olympic Committee, but it is still impossible to test, and till sure checks are found, one can only count on the personal ethics of the sportspersons concerned.
   Does blood doping really work? Buick et al. and Williams et al. have made some studies in the laboratory. In one study, 11 highly trained male track athletes underwent extensive treadmill testing before and alter phlebotomy with re-infusion of 900mi of antilogous freeze-preserved red cells. The blood doping increased the mean hemoglobin concentration 8% (from 15.1% to 16.3% gnm/100ml) , maximal oxygen consumption 5% , and running time to exhaustion 35%. In another study, 12 experienced male distance runners who received 920ml of antilogous blood had a mean 7% increase in hemoglobin concentration and a mean 45-second improvement in time on a 5-mile treadmill run, compared with results after they received 920m1 saline. In the third study, 9 male college students who received two units antilogous blood had a significant increase in hemoglobin concentration and maximal oxygen consumption on a cycle ergo-meter.
   It is reasonable to conclude that blood doping does work when properly performed in the laboratory. But does it work in the field?
   The problem in determining if blood doping works in the field is that almost all the reports are anecdotal. Whether it works or not, blood doping as it was done for the U.S. Olympic cyclists is to be condemned. Three of the cyclists developed flu-like symptoms 36 hours after transfusion, and one of them, when asked about blood doping, said, "Yeah, I did it. I got sick and it ruined me for the Olympics." To be sure, some of the cyclists who blood-doped won medals, but so did some who refused blood doping. Likewise, not all Olympians who admitted to blood doping were medal winners: an Italian runner who blood-doped for the marathon said he ran poorly and the national cross-country team alleged to have blood-doped ran poorly. In short, one cannot tell from anecdotal reports whether or not blood doping works in the field. [br] Blood doping increases the capacity for oxygen delivery by

选项 A、enlarging muscle fibers.
B、increasing blood flow.
C、raising hemoglobin count.
D、making an athlete’s mind active.

答案 C

解析细节题。第二段中提到"This increases the body’s hemoglobin count，hereby increasing the capacity for oxygen delivery…”，因而答案是C

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