This study aims at determine if Progressive Heavy Load Exercises (PHLE) as treatment for patients diagnosed with Rotator Cuff Tendinopathy is superior to "Standard Low-Load Exercises" (LLE).

The trial will be performed as a multicenter randomised controlled trail, including 110 patients diagnosed with Rotator Cuff Tendinopathy from four orthopaedic shoulder clinics in secondary sector in Denmark.

The PHLE intervention will consist of progressive strengthening exercises performed with heavy load dumbbells, targeting the rotator cuff in a 12 weeks home-exercise program with six control visits at a physiotherapy department at the hospitals.

The LLE exercise program consists of the same exercises as the PHLE, but performed with low load dumbbells.

"Disability of the Arm, Shoulder and Hand (DASH) questionnaire" is used as the primary outcome and is measured 12 weeks post baseline.

12 months post baseline a secondary follow-up will be performed primarily measuring the number of patients referred to an operation.

Patients will be randomised to either PHLE or LLE regime by blocks according to whether they have been referred to corticosteroid injection by their orthopaedic shoulder specialist.

*April 2015: (We originally expected to be able to include 260 patients in order to analyze our data according to the sub-groups of exercise group +/- Corticosteroid injection, but inclusion rate has been much lower then expected, and due to time restraints we only expect to include 110 patients)

Primary investigator and patients will be blinded towards group assignment.

Inclusion Criteria:

• Patients between 18 and 65 years of age
• history of shoulder complaints lasting at least 3 months prior to enrolment
• Pain located in the proximal lateral aspect of the upper arm (C5 dermatome) aggravated by abduction
• Positive "Full Can test" AND/OR "Jobes test/Empty Can test" AND/OR "Resisted External Rotation test"
• Positive "Hawkins-Kennedy test AND/OR Neers test
• Ultra-sonographic verification of tendon swelling, hypo echoic areas, fibrillar disruption or neovascularization in the RC.

Exclusion Criteria:

• Resting pain more than 40 mm on a visual analogue scale (VAS);
• Bilateral shoulder pain
• Less than 90 degrees of active elevation of the arm;
• Full thickness RC rupture verified by ultra-sonography;
• Corticosteroid injection within the last 6 weeks;
• Radiologic verified fracture, calcification larger then 5 mm (vertical distance) in the RC tendon, glenohumeral arthrosis or malalignment in the shoulder complex;
• Prior surgery or dislocation of the affected shoulder;
• Clinically suspected labrum lesion, arthritis in the AC-joint, frozen shoulder or symptoms derived from the cervical spine;
• Sensory or motor deficit in neck or arm;
• Suspected competing diagnoses (e.g., Rheumatoid arthritis, Cancer, Neurological disorders, Fibromyalgia, Schizophrenia, Suicidal threatened, Borderline personality disorder, or Obsessive Compulsive Disorder);
• Pregnancy;
• Inability to fluently understand written and spoken Danish.