he made a mistake once. i believe he has been clean for all of his career except that one fight.
The difference between endogenous EPO and recombinant human EPO is not very big," said Carsten Lundby, a senior scientist at The Copenhagen Muscle Research Center in Denmark. A recent study led by Lundby of eight males injected with human EPO and then monitored while riding stationary bikes showed poor detection of EPO in independent tests done at two labs.
While so-called Lab A found positive results for all participants during the weeks when the drug was administered every other day, Lab B found no positive EPO tests.
Three weeks after the last EPO injection, only two out of 48 urine samples showed up as positive in lab tests. Nonetheless, the total red blood cells and aerobic capacity of the participants were still elevated at that time.
"What Carsten has confirmed, what people sort of thought was going on, is that it would be possible for most people to use low doses of the stuff [EPO], enough to get an edge," Joyner told
LiveScience, "but in a way that wouldn't be detected."
That's just one of the reasons EPO urine tests, which began in 2000, have been fraught with challenges. In addition, EPO is short-lived, remaining in the body for as short a time as two days.
"So somebody could cheat on Monday and if the drug-testers came on Wednesday, 48 hours might be enough for the stuff to be gone," Joyner said. But the performance effects, he added, can remain for 90 days or so.
"Some of these compounds have short-acting periods of time in the body, but the biological effects, the positive effects on performance, can be weeks or months," Joyner said.
In addition, cheating athletes and those who administer their drugs constantly work to sneak under the testing radar, finding the lowest doses possible that still have performance effects or figuring out when to inject the drugs to beat testing. "The cheaters are in a constant cat-and-mouse game with the authorities," Joyner said. "They're always changing their strategies in an effort to beat the tests."
https://www.livescience.com/32388-what-is-blood-doping.html