BFRT for Subacromial Pain

The goal of this pilot clinical trial is to learn if blood flow restriction training is safe and feasible in patients with subacromial pain. The main questions the investigators aim to answer are: * What problems do participants with shoulder pain encounter when training with blood flow restriction? * Is it feasible to apply blood flow restriction training as part of a physical therapy intervention? * What are some preliminary effects of blood flow restriction training on the recovery of shoulder function and strength? The investigators will compare active blood flow restriction training to sham (an inactive procedure designed to mimic the active training as closely as possible). Participants will: * Visit the clinic for physical therapy visits and exercise with blood flow restriction training for up to 8 weeks * Visit the clinic for tests before starting the treatment, during the treatment (4 weeks), and after the end of the treatment (8 and 26 weeks).