Having said this, I am wary of setting up an incentive system where you're encouraging people to achieve superior performance during seconds or minutes at potentially high long-term cost.

Perhaps I was unclear. My point is that this happens even without performance enhancing drugs. I know a few people who have permanently injured themselves from sports training and performance, and I'm very confident none of them took performance enhancing drugs. I am not convinced that legalizing performance enhancing drugs would make this worse, and I think it stands a good chance of making it better by putting it all out in the open. I'd be interested in seeing if there's evidence either way.

How well do you think this will work in e.g. Kenya or Myanmar? Don't forget that we have empirical data -- e.g. East Germany in the 1970s and 80s.

Certainly, some doctors are better or worse than others. Athletes may get inappropriate prescriptions if prescription drugs are approved for athletics. Again, I don't really see your point given that I think poor training is comparably dangerous.

As for the latter example, it seems to me that the problems in East Germany were not from use of performance enhancing drugs per se (though they played a role), but lack of informed consent, secrecy, and short-term thinking. Their system considered the athletes to be fungible, and valued short term winning over the athletes' health. And it's not drugs that did all of the damage; hard training (perhaps made more possible with drugs) is a major culprit as well. Athletes should have a choice about whether to take certain drugs or participate in certain training exercises, and they should understand the true risks involved with each choice. They should do this without coercion and be allowed to get other opinions.