An Investigation Into Force Sense at the Shoulder

Proprioception is assessed more often through joint position sense and kinesthesia than force sense. The purpose of this study is to investigate force sense at the shoulder. A total of 12 subjects were recruited. An ipsilateral force reproduction protocol at the shoulder at 50 degrees, 70 degrees, and 90 degrees and 120%, 140%, and 160% baseline torque. Dependent variables were constant error (CE) and root mean square error. An effect was found for load on absolute (p =.001) and normalized CE (p <.001). CE decreased with increased load. An effect for angle was found for absolute root mean square error (p =.002), more accurate at 50 degrees (p =.01), but no effect when normalized (p =.19). With increased loads, subjects undershot the target and CE approached zero. Because of the differing behavior in CE and root mean square error, and absolute and normalized data, force sense studies should examine error from these perspectives.