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The effect of walking speed on local dynamic stability is sensitive to calculation methods
Jan Stenum1, Sjoerd M Bruijn2, Bente R Jensen1
1Biomechanics and Motor Control Laboratory, Section of Integrated Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark.
Journal of Biomechanics
|October 15, 2014
Summary
Different methods for calculating local dynamic stability (λS) yield conflicting results regarding walking speed effects. Researchers must carefully consider the calculation method when interpreting stability findings.
Area of Science:
- Biomechanics
- Dynamical Systems Theory
- Human Locomotion Analysis
Background:
- Local dynamic stability (λS) assesses gait stability by measuring trajectory divergence in state space.
- Previous studies report conflicting effects of faster walking speeds on local dynamic stability.
- Methodological variations in λS calculation may explain these discrepancies.
Purpose of the Study:
- To investigate the impact of different calculation methods on the relationship between walking speed and local dynamic stability.
- To determine if variations in λS computation influence observed effects of gait speed on stability.
Main Methods:
- Ten healthy participants walked at five speeds (60-140% of preferred).
- Upper body accelerations were recorded.
- Local dynamic stability (λS) was calculated using three distinct methods based on time/stride intervals.
Main Results:
- Method (a) showed a minor effect of walking speed on λS.
- Method (b) indicated decreased stability at faster speeds.
- Method (c) suggested increased stability at faster speeds, contrasting with method (b).
Conclusions:
- The effect of walking speed on local dynamic stability is significantly dependent on the chosen calculation method.
- Comparisons across studies using λS require careful consideration of the specific methodology employed.
- Standardization or clear reporting of λS calculation methods is crucial for consistent interpretation in gait analysis.
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