Effect of US-Guided PNM in CrossFit With Nonspecific Shoulder Pain

The US-guided PNM intervention will be performed with the patient in the prone position, the shoulder to be treated flexed at 90 degrees, the humerus partially supported on the table, the elbow flexed at 90 degrees, and the musculature relaxed. Needles will be inserted near the perineurium of the axillary and suprascapular nerves. Prior to needle insertion, the skin will be cleaned with isopropyl alcohol and chlorhexidine. The PNM intervention will consist of applying a compensated asymmetric biphasic current, with a rectangular positive phase and a triangular negative phase, at a frequency of 10 Hz, pulse width of 240 μs, and the maximum tolerated intensity that elicits a painless maximal muscle contraction, following this protocol: 10 stimulations of 10 seconds each, with a 10-second rest between stimulations.

Same intervention as previously described, with the only difference being that the frequency will be 1 Hz instead of 10 Hz.