Effects of Percutaneous Electrical Stimulation in Patients With Chronic Supraspinatus Tendinopathy

The aim of this clinical trial is to evaluate the effects of two percutaneous stimulation techniques-Percutaneous Electrical Stimulation (PENS) and Percutaneous Electrolysis (PE)-combined with a therapeutic exercise (TE) program for the shoulder joint complex, on pain and function in individuals with chronic supraspinatus tendinopathy. The main question this study seeks to answer is: Would incorporating percutaneous electrical stimulation (PENS) of the axillary and suprascapular nerves and galvanic percutaneous stimulation (PE) of the supraspinatus tendon into a therapeutic exercise (TE) program for the shoulder joint complex improve therapeutic outcomes in terms of pain, function, and upper limb disability? Based on an exercise program in all groups, researchers will compare the efficacy of active PENS and PE, as well as placebo, in all their combinations. Participants will undergo a 12-week exercise program, during which they will receive four sessions (one session per week) of active percutaneous electrical stimulation or a placebo during the first month. Participants will: * Visit the center on four separate occasions for results measurement. * Keep a session log to verify adherence to the exercise program.