Inter-joint coordination of posture on a seesaw device

Area of Science:

• Biomechanics
• Neuroscience
• Human Movement Science

Background:

• Postural control relies on complex multi-joint coordination.
• Previous research has not accurately assessed multi-joint coordination on a seesaw device.
• Understanding postural adjustments on unstable surfaces is crucial for human movement science.

Purpose of the Study:

• To investigate multi-joint coordination during postural control on a seesaw versus a stable surface.
• To examine the influence of visual input (eyes open/closed) on postural coordination.
• To explore the neurophysiological mechanisms underlying postural adjustments using intermuscular coherence.

Main Methods:

• Principal Component Analysis (PCA) and Self-Organizing Maps (SOM) were used to analyze joint angles.
• Intermuscular electromyography (EMG) coherence was analyzed to assess neural control.
• Eighteen healthy subjects performed postural tasks on a seesaw and stable ground with eyes open and closed.

Main Results:

• A multi-joint organization of posture was evident on both stable and seesaw surfaces.
• Higher variability in individual postural responses was observed on the seesaw.
• Reduced intermuscular coherence was found on the seesaw without vision, suggesting increased reliance on proprioception.

Conclusions:

• Inter-joint coordination in postural control is significantly modulated by stance conditions.
• The findings challenge the notion that ankle mechanisms solely dominate postural control on seesaw devices.
• Sensory reweighting, particularly increased proprioceptive reliance, likely underlies postural adjustments in altered sensory conditions.