Evaluating Joint Position Sense With 3D Motion Capture System: The Effect of Muscle Activation Without a Reference...

Area of Science:

• Biomechanics
• Neuroscience
• Kinesiology

Background:

• Joint position sense (JPS) is crucial for motor control and is often assessed using joint position reproduction (JPR).
• Traditional JPR methods lack reference angles, posing a significant limitation for accurate assessment.
• This study addresses the challenge of JPS evaluation without a direct reference angle.

Purpose of the Study:

• To investigate the accuracy of reproducing a relative joint angle (50% of a previously achieved angle) during shoulder flexion and abduction.
• To evaluate the influence of different muscle activation conditions (passive, active, active with added weight) on JPS accuracy.
• To determine the reliability and accuracy of JPS assessment without a reference angle.

Main Methods:

• Participants performed shoulder flexion and abduction to a 90° absolute target, with the achieved angle recorded.
• A relative target angle (50% of the achieved angle) was then set for reproduction.
• JPS was tested under passive, active, and active with additional effort conditions for both shoulder movements.

Main Results:

• Significant deviations from the absolute 90° target were observed in both shoulder movements.
• Between-trial reliability (ICC) increased with muscle activation in both flexion and abduction.
• Joint position error improved with muscle activation in shoulder flexion but not significantly in abduction; added effort did not yield further improvements.

Conclusions:

• Reproducing target joint angles without a reference angle presents a considerable challenge.
• Muscle activation enhances the reliability of JPS assessment, particularly in shoulder flexion.
• Findings offer preliminary insights into proprioceptive assessment in clinical and sports settings, relevant for rehabilitation and performance optimization.