Shake with shoulder as lie on a belly.

A lie on a belly, under head are  rolled towel , wrists hands crossed till lock and put on buttocks. Straightened and crossed hands locked move till head  side,like shaking shoulders, and here are stretching a side between a shoulder blades and moving they are.
Here are two variants for exercises as isometric as keeping raising shoulders within 30 sec, return back, after resting repeating exercise, whole repeats are three.

Dynamic as slowly alternately shake shoulders and move crossed wrists, delay  for two sec, as on edge pose,whole repeats are 12.