Participants assigned to this group will received four sessions (once per week) of ultrasound guided percutaneous electrical nerve stimulation targeting the axillar and suprascapular nerves for 30 minutes. We will apply a biphasic compensated electrical current at a frequency of 2 Hz, a pulse width of 250 μs and intensity allowed over a pain-free motor threshold (muscle contraction). In addition, they will receive a program of exercises for the shoulder musculature for 3 weeks.

Participants assigned to this group will received four sessions (once per week) of placebo ultrasound guided percutaneous electrical nerve stimulation targeting the axillar and suprascapular nerve. The electrical current will be off and no electrical current will be provided to the patient. In addition, they will receive the same program of exercises for the shoulder than the experimental group for three weeks.

Participants assigned to this group will receive the same program of exercises for the shoulder than the remaining groups for three weeks.

Application of a electrical current percutaneously (at the motor response intensity) targeting the suprascapular and axillar nerves

The Disabilities of the Arm, Shoulder and Hand (DASH) will be used to determine the disability induced by shoulder pain

A 10-point Numerical Pain Rating Scale (NPRS; 0: no pain, 10: maximum pain) will be used to assess the patients' mean level of shoulder pain experienced in the preceding week in the shoulder area.