Subjects will sign the informed consent prior to any examination procedures. Eligibility assessment will be performed by the treating physical therapist and will include the subject filling out the demographic / health history questionnaire, outcome measures, and a clinical examination. The treating physical therapist will use 2 components of the examination for eligibility criteria into the study. The treating therapist will press on the subject's joints in their back to try to elicit their chief complaint. The treating physical therapist will also press on the muscles of the subject's back to check for any trigger points. A trigger point would include recreation of their chief complaint, tenderness, hypersensitivity, or referred pain. The treating physical therapist will then draw an X on the patient's back where the trigger point (myofascial trigger point or MTrP) exists. This point will be used by the data collecting physical therapist in order to collect pain pressure threshold of the trigger point.