100% agree. Hang out at altitude for a bit. Use a cryo-chamber. Even the pain-killer tramadol. None of those are illegal and all are arguably 'performance-enhancing'. Fuck it sure you could extend the argument to taking an energy gel or eating a banana.
Absolutely theres a grey area there.
Conversely you could argue theres nothing wrong with blood doping. Its your own blood after all and theres most likely no banned substances in there.
Honestly I have no idea how or where or why they make the rules as they do. The majority of doping doctors believe they are helping athlete's (particularly endurance athletes) health by juicing them. Thats how they can lie as brazenly as they do.
If there was a major doping positive in soccer I don't get the impression there would be any sense of outrage among soccer people. Even in cycling, which is rotten as fuck, the outrage only comes if you thought the cyclist was a wanker to begin with. Thats why people are so forgiving of Contador yet are baying for Chris Froome's head on a platter.
Its all fucked up.
