Effects of multi-joint coordination and motion plane on shoulder and elbow joint position sense

BackgroundThe shoulder and elbow differ in their anatomical structure and physiological function, which can lead to differences in joint position sense (JPS) accuracy. However, most previous studies have assessed JPS in single-joint motions across multiple planes.ObjectiveThis study aimed to compare the joint position error (JPE) between single- and multi-joint motions and investigate how motion patterns and planes of motion influence proprioceptive accuracy.MethodsThe single-joint motion involved flexion of either the shoulder or elbow to a target angle of 45° without reference. The multi-joint motion included simultaneous shoulder and elbow flexion (SF-EF) and shoulder abduction with elbow flexion (SA-EF).ResultsIn the single-joint motion, the shoulder exhibited a lower JPE and higher reliability than those of the elbow. In multi-joint motions within the same plane (SF-EF), the shoulder JPE increased significantly, whereas in multi-joint motions across different planes (SA-EF), the JPE decreased.ConclusionIn single-joint motions, the shoulder has superior proprioceptive acuity compared to the elbow, which may be attributed to differences in peripheral sensory mechanisms and segment-based motor control within the central nervous system. In multi-joint motions, proprioceptive distortion owing to summation effects was observed in a single plane, but not in multiple planes.