Movement Direction and Shoulder Orientation Alter Elbow Joint Position Sense

Proprioception is the body’s ability to sense its position and movement without visual input. Proprioception of the elbow and shoul- der has been shown to be most accurate when elevation or flexion angles are at 90 degrees. Investigations in shoulder orientation and movement direction may lead to a better understanding of what is playing the largest role in this heightened sense at 90 degrees. This study looks at the effects of shoulder orientation and movement direction on elbow joint position sense (JPS). With an aim to look at what is increasing proprioceptive acuity as you increase flexion angle to 90 degrees, we predicted that an increase in shoulder orientation would increase elbow JPS, but movement direction would have little effect on JPS. Subjects had the same 3 target angles; 50, 70, and 90 degrees, that the subjects would memorize their elbow position then actively mimic the position. There were two different 2-way interactions found; one between angle and orientation, and another between movement direction and shoulder orientation. This indicates that elevating your shoulder to 90 degrees increases elbow JPS. Also, extension at the elbow may be lead to better elbow JPS than flexion, yet shoulder orientation possibly negates this effect. Analysis is ongoing and further conclusions are in development for this study.