But I think at that level most athletes, meaning half or better (I think way more) are doing something.....HGH is a big one because within 24 hours of injecting it cannot be detected in urine which is why the NFL wanted blood testing but the union said no way. Then there are the myriad of steroids that cannot be decected and the like and of course blood doping. The guys who cheat are always ahead of the curve.
Not that many years ago, right before Lance Armstrong was FINALLY busted, I had a conversation with a guy who was also a cyclist....... he competed nationally/regionally/locally but was not decorated. I asked him about Armstrong and the couple of guys who had been caught and stripped. His response was simple and straightforward. He said in regards to cycling that nobody "good enough" to compete on a national/global scale was clean that he knew of and that in his opinion most athletes in most of the sports in games were guilty as well.
Sadly I think he is probably right though he is more jaded than I am having seen some of it first hand.