Well not necessary Supraspinatus. Impinchment likely. You need to do some testing here. Like empty can, scarf test. Supraspinatus most active early abduction, stretched on adduction. With abduction and flexion there is a lot of pressure on AC Joint. and so on. So you need to look into the biomechanics of the shoulder(girdle) and possible neuro irritation before you can answer this question. Work to do!