Why do anabolics appear to target more effectively the shoulders and traps?
At first blush, the assumption seems kind of preposterous: Do they? Why should steroids be more effective in these anatomical areas?
The available research literature says this assumption has a lot of traction and suggests that the answer lies in the surprising (at least to me) conclusion that the use of anabolic steroids appears to cause up-regulation at these sites more reliably than it does in other muscles like the biceps, triceps or vastus laterals.
It looks as if these chemicals do this trick by positively modulating the numbers of myonuclei in the muscle cells of the neck and traps, much more so than seen in the other muscle groups. In other words, there seems to be either 1) more receptor sites in these areas, 2) the targeted receptor sites possess an increased sensitivity or 3) perhaps it is a combination of both these characteristics affecting up-regulation.
The reason for this odd distribution and peculiar state of things has yet to be elucidated.