There has been massive amounts of bro science flying around the panels in regards to this topic.. The truth of the matter is, your AR's are expressing up-regulation especially under the presence of more androgens..However, what people have mistaken and fail to understand is that in relatively high concentrations of AAS there will be a significant competition when approaching the metabolizing enzymes..There is many binding sites on a cellular level, so more growth, more targeting sites.An other factor is , some androgens will have a greater influence with hematosis reaction by increasing cortisol,glycogen, and SHBG,estro,e1/e1 progest (for some 19-nors) and this is where competition and binding can become an issue for some users in regards to what seems like "cancellation of a compound"..
When running multi compounds, keep the dose moderate, no need for heavy dosages.. increase one, and other levels will go up,its called system balance of checks, this is what may render some compounds useless..However, not all AAS are targeting AR's, some target the outside of the cells,for the compounds that are non AR mediated they also posses anti caabolic properties.. The end result here,the conclusion is, AAS work by more then one mechanism, from satellite cell differentiation,CNS and neurotransmitter improvement/firing and signaling within pathways, and so on..There's always a molecular change taking place..People should be more concerned with estro/progestin competing rather then compounds against each other, because therein lies the problem!
By the way, Tren and nandrolone are both synthetic progestins that is why some will advocate not to use them both (hog wash, both are fine depending on the users sensitivity) and both have different targeting properties yet sharing similar goals..Why is one a thermogenic compound and the other doesn't posses nearly as much aggression as the other?