Well, I guess just that the most exceptional athletes will have the most exceptional physiology - it's not all about blood though. Dr Hutch talks about it in Faster - there's many things (6 or so?) that go into making an endurance cyclist the best, and the chance of having all six being really high in one athlete are vanishingly small.
From memory, we're looking at VO2 max, efficiency, haematocrit, muscle fibre type, erm... can't remember the rest. Obviously of these, blood is one you can artificially enhance quite easily.
Well, I guess just that the most exceptional athletes will have the most exceptional physiology - it's not all about blood though. Dr Hutch talks about it in Faster - there's many things (6 or so?) that go into making an endurance cyclist the best, and the chance of having all six being really high in one athlete are vanishingly small.
From memory, we're looking at VO2 max, efficiency, haematocrit, muscle fibre type, erm... can't remember the rest. Obviously of these, blood is one you can artificially enhance quite easily.