My lady has shoulders that move up and down, and forwards and backwards. Is the forwards and backwards what you mean by rotating?
The way I read it is that the shoulders are moving forwards when you lift the arms up. Does this happen when you lift the arms straight up from the front or the sides?
This doesn't happen with my gal, instead I have to move her arms into position first, then push, pull or lift etc. But, her shrug shoulder joints are still firm.
eco
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