Here it is written, about the Overhead Press, that
At the bottom position, you need to be initiating the press in something called the scapular plane. Such that at the bottom position your elbows are pointed slightly forward, or in other words at roughly a 30 degree angle from directly sideways.
First question: is the choice of working in the scapular plane made to reduce shoulder impingement (like in lateral raises)? If it is, can you explain me why? Does having a 30 degree angle between the elbows and the frontal plane creates space between the humerous and the AC joint for the rotator cuff tissues?
Then, always there, it is written that:
Then only as you press up should you naturally allow your elbows to turn out to the side.
In summary, you should start with your elbows in the scapular plane. But then, gradually during the movement, they will slowly start pointing outwards (first picture below) and will continue pointing outwards at the top (second picture below).
Second question: why is this necessary? Why can't we continue the movement with our elbows in the scapular plane?
Third question: How can we avoid shoulder impingement? Here it is written to shrug at the top, since this will create space between the humerus head and the AC joint for the rotator cuff tissues. That is fine, but what about the rest of the way up (it is written to shrug at the top, not during the way up).
A situation like this:
seems to me quite similar (from the elbows point of view) to this in the bench press
except for the fact that in the overhead press the forearms are rotated backwards compared to the bench press scenario. Is this that avoids shoulder impingement?