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Two independent contributions to step variability during over-ground human walking
Steven H Collins1, Arthur D Kuo
1Department of Mechanical Engineering and Robotics Institute, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America.
Plos One
|September 10, 2013
Summary
Human walking step length variations are mainly due to speed changes, while step width variations are linked to balance control. This suggests distinct neural control mechanisms for fore-aft and lateral foot placement during locomotion.
Area of Science:
- Biomechanics
- Neuroscience
- Human locomotion
Background:
- Human walking shows variability in step length and width.
- Some variability is linked to active balance control, particularly lateral balance adjustments via step width.
Purpose of the Study:
- To investigate if step length variations are primarily driven by walking speed fluctuations.
- To determine if step width variations are independent of speed and related to balance control.
- To differentiate between speed-related and balance-related components of walking variability.
Main Methods:
- Analysis of hundreds of overground walking steps from healthy young adults.
- Examination of step length and width variability in relation to self-selected walking speed fluctuations.
- Comparison of walking with eyes open versus eyes closed to assess lateral balance control.
Main Results:
- Slow fluctuations in walking speed explained most step length variance (59%).
- Step width variability was significantly greater than step length variability (4.3x) and independent of speed.
- Walking with eyes closed increased step width variability, indicating impaired lateral balance control.
Conclusions:
- Step length modulation is precise and primarily coupled to slow walking speed fluctuations.
- Step width modulation is more variable, occurs on faster timescales, and is related to lateral balance control.
- Walking variability can be separated into distinct speed- and balance-related components, offering insights into neural control of locomotion.
