Barber Pole, yes, the practice is called blood doping. It's not exactly allowed, but it's pretty much indetectable, being the athlete's own blood. I think there was an Eastern bloc athlete who died in connection with improperly stored blood, and some US athletes who contracted hepatitis because they didn't use their own blood.
http://www.tc.cc.tx.us/~mstorey/beckham.html
Maybe if you do a whole lot of flogging around at 10,000' in unpresurized aircraft before you get that jet job your body will be acclimatised to altitude and you'd have more useful consciousness in the even of a depressurization.