This is not strictly running, not running at all but can be translated in to the running world if you consider the posture information in this podcast that I’m about to share.
This particular podcast talks about how the mobility and posture of your thoracic spine can be a causing factor of shoulder pain that you maybe experiencing.
For runners with shoulder pain who I’ve seen recently , your posture and ability to move through that mid back area could be a key to shoulder pain. Mobility is extremely important, not just strengthening and stretching.
Here is the episode of The Modern Desk Jockey
Let me know your thoughts