Zapping the brain while exercising shoulder: new hope for pain relief?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Subjects will be evaluated during a first consultation by a physiotherapist with experience in shoulder musculoskeletal pathology, following the algorithm for the diagnosis of shoulder problems, recommended by the British Elbow \& Shoulder Society with the aim of detecting possible "flags red" and as a guide to rule out other shoulder pathologies that do not fit into the SDS. However, other tests will be added to ensure diagnostic accuracy, and these are described below. Inclusion Criteria: 1. Age between 18 and 65 years. 2. Duration of pain greater than or equal to 3 months. 3. Presence of 3 or more of the following positive clinical tests: * painful arc * External rotation test against isometric resistance * Neer's test * Jobe test or empty can test * Hawkins-Kennedy test Exclusion Criteria: 1. Previous shoulder or neck surgery. 2. History of shoulder fracture or dislocation. 3. Medical diagnosis of shoulder osteoarthritis. 4. Adhesive capsulitis 5. Cervicobrachialgia or reproducible shoulder pain with neck movements. 6. Clinical signs of total tear of the rotator cuff. 7. Corticosteroid injection in the previous 6 weeks. 8. Inflammatory disease, autoimmune or rheumatic, systemic (arthritis, lupus, myopathies). 9. Cognitive or behavioral problems that make it impossible to understand and follow the intervention (score less than 24 on the Mini-Mental State Examination Score) (73). 10. Any neurological or neoplastic disease. 11. Also those who present contraindications for transcranial electrical stimulation. For this, the recommendations of the checklist of Thair et al. which includes: * personal and family history of epilepsy * metal implants in the head * implanted medication pump * pacemaker * recurring headaches * skin diseases of the scalp (psoriasis, eczema) * head injuries * serious head surgeries * pregnancy * heart diseases * medications (psychotropics or antihistamines).