Therapeutic Exercise for Rotator Cuff Tendinopathy / Subacromial Pain Syndrome - Outcomes and Mechanisms

Inclusion Criteria: 1. the clinical diagnosis for RC tendinopathy will be made with positive 3 of 5 tests: Hawkins-Kennedy, Neer, painful arc, empty can, external rotation resistance test 2. pain ≥ 3/10 on a numeric pain rating scale 3. age: 18 - 45 years 4. Participant must read, sign and date the appropriate Informed consent document. 5. Participant BMI ≤ 30 Exclusion Criteria: 1. Insufficient ability to comprehend and complete the questionnaires, 2. Inability to attend sessions, 3. Prior surgery of shoulder, neck or thoracic spine, 4. Primary complaint of neck or thoracic pain, 5. Diagnosis of cervical spinal stenosis, 6. Any serious spinal and shoulder pathology: infections, arthrosis, rheumatic disorders, acute fractures, shoulder dislocation, osteoporosis, or tumors, 7. Central Nervous System involvement, to include hyperreflexia, sensory disturbances in the hand, intrinsic muscle wasting of the hands, unsteadiness during walking, nystagmus, loss of visual acuity, impaired sensation of the face, altered taste, the presence of pathological reflexes (i.e. positive Hoffman and/or Babinski reflexes, 8. two or more neurologic signs of nerve root compression to include myotomal weakness, positive muscle stretch reflex, and dermatomal sensory loss, 9. any shoulder or arm pain with cervical spine tests of Spurling's Test, cervical rotation to the ipsilateral side, or axial compression test, or 10. primary adhesive capsulitis defined by passive range of motion loss \>50% as compared bilaterally of shoulder external rotation, internal rotation, or elevation. 11. Has a device or other condition that is not safe for MRI, including pacemakers.