I've got a hypothesis that highly trained, particuarly alitutude trained, runners should benefit the most from EPO use. What's wrong with the following argument?
Personally I'm dubious that altitude training reduces the effectiveness of EPO for the following reason. One of the most pronounced changes due to training, particularly altitude training, is an increase in blood plasma volume. This increase is so dramatic that even though altitude training stimulates increased red blood cell (RBC) production, hematocrit (RBC concentration) tends to drop during training, even at altitude. While there are more RBCs, there is even more volume of fluid to dilute them. Why don't RBCs keep up to maintain or even raise the hematocrit? Likely because the human body is evolved to be overly cautious about increasing RBC production because if too high, blood viscosity can increase to the point that clots happen. The point is that the body fears clots more than it cares about optimal performance so the hematocrit is naturally set below optimum distance running levels. That's why EPO helps untrained but otherwise healthy people run faster. Highly trained people and particularly those trained at altitude, however, have lower hematocrits due to their vastly increased blood volume. In theory this should give them more room to increase their hematocrit via injection of EPO or red blood cells (blood doping). Unless there is some other factor at work here, it seems obvious that highly trained runners, particularly altitude trained runners, should be able to tolerate a lot more EPO than everyone else and therefore see larger gains in performance before blood viscosity increases to dangerous levels.