 While the angle of the instrument may change as this motion follows the shape of the teeth and placement of the jaw, contrary to what many brass performers and teachers believe, the angle of the instrument does not actually constitute the motion Reinhardt advised as a pivot.Later research supports Reinhardt's claim that this motion exists and might be advisable for brass performers to adopt.John Froelich describes how mouthpiece pressure towards the lips (vertical forces) and shear pressure (horizontal forces) functioned in three test groups, student trombonists, professional trombonists, and professional symphonic trombonists.