I demonstrate shoulder instability in this video and explain shoulder injuries from paddling sports.
The mechanism for shoulder impingement injury is explained in this video.
Poor flexibility in the upper trunk or an unstable shoulder means that the shoulder impinges on the joint. This situation can be created and exacerbated by poor posture (EG, sitting at work at a computer).
I suggest rotational movement routines or exercises using the TRX suspension trainer as examples of how to correct imbalances and mitigate injury.
