Ok so exogenous, my main questions pertains to endogenous, but thank you for pulling all that up, appreciate your time
Hey, no problem man.
Although I understand that it wasn't exactly what you were looking for.....
Consider this .... IMO, it is closer to the answer than the initial link that you posted. ... The reason being, that one was product focused. Product was introduced, and some of the results were: higher Testosterone, lower DHEA, etc.
Although we (and I don't believe they) know for sure the exact reasons for these particular effects, the study was assuming a cause effect relationship between the product and the effects, not a causal relationship between the effects themselves.
Although the studies I pulled up weren't specifically "Endogenous" Testosterone focused, they are higher Testosterone focused. (Higher Testosterone = these effects).
I personally believe it will be difficult to find exactly what you're looking for, because it would be difficult to determine a causal relationship. I believe it would take a massive research project, that still might encounter problems with cause and effect.
Not the least of which would be the fact that it Could be that it makes no difference where the Testosterone came from.