 Subjects will be recruited from a population of convenience. After consenting to participate, eligible subjects will complete a demographic questionnaire and pretesting of scapular and shoulder mobility. Two days of testing will be scheduled. On the first day, three grades of glenohumeral mobilization will be applied in the following directions: distraction, posterior and inferior. A handheld dynamometer will measure force; ultrasound imaging will record glenohumeral joint position. Each grade and direction will be repeated three times on the right and the left shoulder. On the second day, the mobilizations will be repeated. Measurements of humeral movement will be calculated from the ultrasound images. 