Will injecting a small amount of cortisone suppress endogenous cortisol and lead to more muscle growth?
Forget about if it increases muscle growth or not… which it won’t. That is not the way you go about lowering cortisol. If you want to lower cortisol you have to do it in a much safer way than that. If you create adrenal insufficiency, you will be in a world of hurt and your muscle will atrophy wayyy more than having excess cortisol levels.