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Rambling and trembling in quiet standing
1Biomechanics Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, USA.
Motor Control
|August 14, 2001
Summary
Quiet standing involves body sway due to two factors: rambling, the movement of a reference point, and trembling, deviations from that point. These components were analyzed using center of pressure and ground reaction force data.
Area of Science:
- Biomechanics
- Human postural control
- Motor control
Background:
- Quiet standing is essential for daily activities.
- Postural sway in quiet standing is a complex phenomenon.
- Understanding the underlying mechanisms of postural control is crucial.
Purpose of the Study:
- To investigate the rambling-trembling decomposition in quiet standing.
- To analyze the relationship between center of pressure (COP) and horizontal ground reaction force (F(hor)).
- To differentiate between the contributions of rambling and trembling to postural sway.
Main Methods:
- Utilized a force platform to record COP and F(hor) in healthy subjects during quiet standing.
- Identified instant equilibrium points (IEPs) where F(hor) = 0.
- Applied rambling-trembling decomposition and gravity line decomposition to COP time series.
Main Results:
- Both decomposition techniques yielded similar results.
- A strong correlation (r=0.91) was found between the trembling trajectory and the COP-gravity line difference.
- Significant negative cross-correlation between trembling and F(hor) (r=-0.90 to -0.75).
Conclusions:
- The findings support the hypothesis that body sway in quiet standing arises from both rambling (reference point migration) and trembling (deviation from the reference point).
- The gravity line moves predictably between IEPs.
- Trembling significantly contributes to postural instability during quiet standing.