Now “if” it’s an instinct, again certain muscles are contracting, even though you may be so used to looking for a feeling of a stretch.
Try that Move
So go ahead and try the same move.
Reach and instead of normally paying attention to what you thought is stretching.
Feel where your muscles contract or tense up.
Could You Feel This?
Were you able to feel your shoulder, upper back, and part of your neck contract?
And when you opened your mouth, did you feel your jaw or even the front of your neck contract as well?
Ok, that's part 1 of a conscious pandiculation.
But wait, you might have felt other muscles contract or chime in too.
See that can depend upon any number of compensations, restrictions or substitution patterns for a normal lengthening of the arm.
Did You Feel This Too?
As you reached the arm up, did you feel or get a sense of your opposite side contracting?
Or as in the definition, did you stiffen your trunk?
If so, I don't know about you, but when I stiffen my trunk, reaching up is entirely another experience.
And this is what some people actually do.
They might brace without realizing it.
Or that can happen from any number of negative life events where we end up bracing or over stiffening just to reach.
So the first time you reached up you may have been mostly focused on reaching the arm (possibly feeling the stretch on that side) and you might not have noticed all the other muscles chiming in.
Another Level of Awareness
That kind of awareness is another level of what is going on in a conscious pandiculation.
Plus, if you did it like the woman here, did you feel how you flexed your wrist back?
As a result, certain muscles of the forearm got involved too.
That could have been conscious or unconscious as part of a habitual pattern where we simply do it or go at it automatically on autopilot.