<qa>  What is the ipsilateral posterior shoulder?This study will assess if DN of a trigger point in the gluteal muscles increases pain pressure threshold in that muscle, in another muscle innervated by the same segment L45 and in an area not supplied by the same segment i.e. the ipsilateral posterior shoulder. In addition, this study will assess if functionality, as measured by the Oswestry Disability Index ODI and 15-point Global Rating of Change Scale GRoC questionnaires, improves after 2-3 treatments 1 week of DN. 