I read years ago that Athletes were injecting themselves with something (cannot remember the name) ,
so that they can train harder and longer without weakening their immune system
This was banned because of unfair advantage, now the tic bean has this naturally in small amounts
and is one of the reasons distance flyers fed them.
Hopefully someone will know more on this subject.
One thing I will say about pigeon racing especially for novice's is that there are many roads that lead to Rome,
meaning if one fancier does things one way, someone down the road will be doing the opposite just as well as that fancier.