[comdpa]

The trunk is not rotating (or being felt doing nothing) does not necessarily mean it's not doing anything. It appears (to the observor) the body is motionless and doing nothing when pushing against a wall (static muscle contraction).

See for yourself by moving the (lagged) arms "without the trunk rotating" while standing on the ground vs. a rotary chair.

bts,

What EdStraker is referring to here is the arms moving across the chest (from their point of origin, the shoulders) with no rotary motion of the trunk.

Remember, the shoulders are a dual agent, being part of both the Power Package and the Pivot. Therefore, arm induced shoulder motion does not necessarily mean the Pivot is involved. 7-13