Triceps Surae Ia Proprioceptive Weighting in Postural Control During Quiet Stance with Vision Occlusion

Area of Science:

• Human movement science
• Neuroscience
• Biomechanics

Background:

• Postural control relies on integrating visual, vestibular, and somatosensory information.
• Reduced sensory input reliability prompts reweighting of remaining sensory systems.
• Muscle vibration can selectively stimulate muscle spindle Ia afferents to assess proprioceptive contribution.

Purpose of the Study:

• To quantify the effect of vision occlusion on triceps surae (TS) Ia proprioceptive weighting during quiet stance.
• To investigate sensory reweighting strategies in postural control.

Main Methods:

• Forty-one healthy young adults stood with eyes open (EO) or eyes closed (EC).
• Bilateral TS muscle vibration (80 Hz) was applied during quiet stance.
• Anterior-posterior ground center of pressure (COP) displacement was measured to quantify postural response.

Main Results:

• The backward COP shift induced by TS vibration was significantly larger in the EC condition compared to EO (p < 10^-9).
• This indicates increased reliance on TS proprioception when visual input is absent.
• Most participants (37/41) showed an increased sway response with eyes closed.

Conclusions:

• Young adults exhibit increased triceps surae Ia proprioceptive weighting for postural control when vision is occluded.
• This suggests a shift towards non-visual sensory feedback for maintaining balance.
• The findings support the concept of adaptive sensory reweighting in response to altered sensory environments.