Performance enhancing drugs

Ryan Braun has come clean that he used banned substances classified by MLB as performing enhancing drugs in order to speed up his rehab for injury. I suspect he is not alone, but the question I have is what are performing enhancing drugs? What are certain agents selected for this forbidden category?

I am sitting in bed composing this piece, waiting for my Starbucks coffee to brew, knowing that after having my first morning cup my writing performance will be enhanced. I may very well play some tennis today, being sure to take a few doses of my NSAID of choice before to lessen the likelihood of pain and stiffness, thus enhancing my performance. Come to think about it, was is not a performance enhancing drug? Maybe only recreational drugs....

When a professional athlete has an injury, he or she is sent to some form health professional who intervenes in some way, presumably trying to restore and enhance their function. These interventions may involve medications, to enhance healing and function (performance). Why are some banned and others accepted? For some injuries injections or oral administration of glucocorticoids are prescribed to enhance healing. So tell my why these "steroids" are acceptable while anabolic steroids are not? 

Not infrequently athletes require surgery to address some issue. Is the surgery only allowed to restore where they were before their injury or is it allowed for the surgery to take them to a new state where their performance is enhanced? Take Tommy John surgery for an example. In these cases the surgeon leaves the athlete in an new anatomical state. Could or should this be viewed as performance enhancing surgery? What if surgical techniques and bionics progresses to a point to where implanted devices really give an edge?

What is it about certain medicinal interventions which is so disturbing that athletic regulatory bodies select them to be forbidden? Presumably all interventions which are not enhancing in their effects would and should not be of interest to any of the parties involved. Athletes will always be looking for anything that gives them an edge and enhances their performance, but that is really true for all of us. What constitutes a legal vs a unacceptable intervention is essentially impossible to define and attempts to define have to deal with the moving target phenomena. There are no clear lines which can be drawn and the ambiguous boundaries are constantly moving. There are no clearly defined principles to delineate the difference between banned substances and widely used ones. The designations appear to come about though whim and gestalt. 

Perhaps this is all part of a larger struggle we have with drugs in general. We understand that drugs can both impair and enhance our function and we seem to have a problem with both of these. Creating legal and regulatory boundaries on their use should yield more benefit than harm. I am not sure that's the case. Maybe we need to consider the possibility that fewer rules in this arena will lead to better outcomes.