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Updated: Sep 26, 2026
Experimental Methods to Study Human Postural Control
Published on: September 11, 2019
Nonlinear analysis of the development of sitting postural control
Regina T Harbourne1, Nicholas Stergiou
1Munroe-Meyer Institute, University of Nebraska Medical Center, Omaha, NE 68198-5450, USA. rharbour@unmc.edu
Insights
Infant sitting postural control develops through dynamic changes in stability and movement patterns. This research reveals how infants learn to control their body
Area of Science:
- Developmental neuroscience
- Biomechanical engineering
- Infant motor control
Background:
- Postural control is crucial for infant development.
- Understanding the maturation of sitting balance is essential.
- Previous research has not fully explored the dynamic nonlinear aspects of this process.
Purpose of the Study:
- To longitudinally analyze the development of sitting postural control in infants.
- To apply nonlinear dynamics methods to center of pressure (COP) data.
- To investigate changes in stability, dimensionality, and complexity during sitting development.
Main Methods:
- Longitudinal study of five normal infants across three sitting stages.
- Nonlinear dynamics analysis of center of pressure (COP) data.
- Measures included Lyapunov Exponent (stability), Correlation Dimension (dimensionality), and Approximate Entropy (complexity/regularity).
Main Results:
- Significant increases in neuromuscular system stability and regularity were observed over time.
- Movement dimensionality decreased from Stage 1 to Stage 2, indicating degrees of freedom constraint.
- Movement dimensionality increased from Stage 2 to Stage 3, indicating degrees of freedom release with emerging independence.
Conclusions:
- Infant sitting postural control develops as a dynamic process.
- Infants learn to control body degrees of freedom for stable sitting.
- Nonlinear dynamics analysis provides valuable insights into motor development.
Abstract:
The development of sitting postural control in five normal infants was examined longitudinally at three stages of sitting: Stage 1, when infants could hold up their head and upper trunk, but could not sit independently; Stage 2, when infants began to sit independently briefly; and Stage 3, when infants could sit independently. Methods from nonlinear dynamics were used to analyze center of pressure (COP) data during sitting in terms of stability of the neuromuscular system (Lyapunov Exponent), movement dimensionality (Correlation Dimension), and complexity/regularity (Approximate Entropy). Results indicated significant changes in the nonlinear measures over time, with increased stability and increased regularity revealing a more stable and periodic strategy of maintaining postural control. Dimensionality decreased from Stage 1 to 2, indicating a constraint of the degrees of freedom. Subsequently, dimensionality increased from Stage 2 to 3, indicating a release of the degrees of freedom as sitting independence emerged. Nonlinear analysis of the COP time series supports the perspective that the development of postural control is a dynamic process whereby the infant learns to control the body's degrees of freedom to achieve the sitting posture.
