Lance Armstrong.
Why they didn’t test him at first will never know.
He was ‘Blood Doping’, using your own red blood cells taken weeks in advance, then just before the race reinserting them into yourself.
Gives more oxygen and thus longer stamina.
there was no test for it then. Now there is...............
They tested him all the time- that was why he was so believable... but he had a very complex blood exchanging scheme in place.
They would give themselves a whole blood transfusion - changing 100% of his blod.
Where you get that much blood should be questioned. I imagine you have to have enough to completely drain you an make sure only fresh blood goes in.