@Steve Rogers: Steve Freides is correct. You really can't think too much when lifting, you will become paralyzed. Can you imagine if you tried to explain all of the muscular actions required to tie your shoes for example, and then try to follow that much detail? Even as you know how to do it automatically, you would start to lock up with indecision, with too much cognition!
A short checklist works best, and that's why I am always looking for cues that resonate with the individual trainees language of movement, as well as proprioceptive devices, rather than cues that I may get, but another lifter may or may not understand.
(So on that note, don't read this post, b/c I'm about to go way, way down the rabbit hole, ha ha!) OK, here goes:
I've been thinking a lot about Dan John's excellent tip to grab the tag on your shirt, and voila, shoulder is packed, and why it is so effective. I believe that I have discovered the common theme that explains the discrepancy in approaches regarding scapular stability vs. dynamic stability: It's the alignment of the T-spine.
To grab the tag on your shirt, requires you to extend and elongate your T-spine. This is both cause and effect of the scapula posteriorly tipping. Much as externally rotating the hips can work upwards to stabilize the pelvis, posteriorly tipping the scapula can act on the T-spine in a closed chain manner. So as the T-spine is fixed, the scapula can roll in the open chain. As the scapula is fixed, the T-spine can extend in a quasi-open chain manner, in response to the lower trap force from below.
So the two muscle groups, the trapezius, and the spinal erectors, work as a "push and pull" team, setting the alignment for the humeri to move.
Here's the area, where I have diverged from the packing approach: I think it is better to absolutely fix the T-spine into hard extension, and this aligns the scapula favorably to move in a more open chain fashion, as opposed to trying to use the scapula to effect the T-spine position. Now, maybe I am just splitting hairs here, as the two actions of T-spine extension, and scapular posteriorly tipping should happen in a coordinated fashion.
But I submit that once the scapula is posteriorly tipped (angled) to open the acromion, the whole ball of wax needs to roll upwards. So if someone is bulletproof strong in the T-spine, then to pack or not to pack is really not even an issue, the "hay is already in the barn", so to speak. The alignment is set.
My personal movement bias is to always think proximal to distal, from the core outwards. Start from the hips and abs, which set up the T-spine, which sets up the scapulae, and further the humeri to move.
Put another way, folk are stable on a machine press. Why? B/c the machine does the work of the glutes, abs, etc. to stabilize the entire torso, and allow the limb to move. Having said that if you lean back into a bench and compress the scapula, then try to press overhead, don't be surprised if you get a sharp and searing pain in your supraspinatus, as the scaps are packed involuntarily, and the humeral head crashes into the acromion. They are now TOO STABLE!
Does it work for a bench press? Moreso, but immobilizing the scaps is the chief reason that the bench press jacks up shoulders, and push ups are more shoulder friendly.
(I think I just wrote an unsolicited guest blog here!) Anyway, thinking out loud.
