It’s such a hard subject because lacking identical twins with identical injuries but one using AAS and the other not, one is always left, in terms of making a comparison, having to do so only versus an estimation of what “would” have happened without the androgen use, or versus what happened on a seemingly similar past occasion, but with of course not everything actually remaining the same.
Or that could be addressed with studies with large numbers of subjects but that is not being done these days.
I have read studies on things such as deliberately inflicted injuries on the external ears of (I think) rabbits and effect of oxymetholone on healing rate – positive – and that sort of thing. And in fact in the 60s doctors and the pharmaceutical industry were fairly enthusiastic about use of androgens to speed healing after surgery and so forth.
They discontinued doing so not out of proof that this use did not work, but because of lack of evidence that it made a difference in long term outcome.
There probably were a lot of unpublished studies by pharmaceutical companies on effect on healing rate in man but I’m not aware of published ones. (Which does not mean that none exist.)
As for whether athletes in sports frequently causing strain injuries, such as baseball, believe that anabolic steroids aid recovery: many are convinced, that is for sure.
Personally I don’t seem to experience a difference regarding recovering from strains but that is one person, and besides that, again it is always guesswork when one person tries to compare against what he estimates “would” have happened had he done the opposite (been using when in fact not using, or the other way around.)