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Updated: May 25, 2026
08:12
Experimental Methods to Study Human Postural Control
Published on: September 11, 2019
Invariant density analysis: modeling and analysis of the postural control system using Markov chains
Pilwon Hur1, K Alex Shorter, Prashant G Mehta
1Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA. hur@uwm.edu
IEEE Transactions on Bio-Medical Engineering
|January 21, 2012
Summary
Invariant density analysis (IDA) quantifies postural control during quiet standing. This new method reveals age-related differences, showing younger adults have more stable and predictable sway patterns.
Area of Science:
- Biomechanics
- Systems Neuroscience
- Human Movement Science
Background:
- Postural control is crucial for stability during quiet standing.
- Assessing steady-state behavior of postural control is challenging.
- Existing methods may not fully capture stochastic dynamics of postural sway.
Purpose of the Study:
- Introduce invariant density analysis (IDA), a novel technique for quantifying postural control.
- Validate IDA's ability to analyze center of pressure (COP) data during quiet standing.
- Demonstrate IDA's utility in identifying age-related differences in postural control.
Main Methods:
- Developed invariant density analysis (IDA) based on a reduced-order finite Markov model.
- Applied IDA to center of pressure (COP) data from quiet standing tasks.
- Utilized five IDA parameters to characterize steady-state postural control dynamics.
- Conducted two studies to assess IDA's efficacy and applicability.
Main Results:
- IDA can effectively use concatenated short trials for analysis.
- IDA successfully differentiated postural control between young, middle-aged, and older adults.
- Young adults exhibited faster convergence to steady-state and maintained COP closer to a centroid.
- Older adults demonstrated higher entropy (more stochastic sway), while young adults showed lower entropy (more deterministic sway).
Conclusions:
- Invariant density analysis (IDA) is a promising quantitative tool for assessing quiet-standing postural control.
- IDA provides physiological insights into the long-term dynamical behavior of the postural control system.
- The findings highlight significant age-related changes in postural sway characteristics.
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