Yes- it was an EMG on the long thoracic nerve.
At the time, I was immediately post-surgery. I had a radial nerve release. Since the the nerve was OK, the doctor thought it was from muscle imbalance, possible guarding behavior or lack of use of that arm (b/c of pain).

And, actually, the exercises did help. I had pain in the scapular area also and that eventually went away (and never came back).