 Secondary analysis: The secondary analysis will compare the three subgroups of patients differing in their symptom duration 0.5-3 months of pain, 3-6 months of pain and 6 months of pain, regarding the 3 main outcomes: CNS sensitization, shoulder muscle function, and shoulder pain distribution, to indicate symptom doseresponse relationships, using descriptive statistics. The symptom duration groups may be redefined, if recruitment is slow for one or more of the groups outlined above. 