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Anticipatory postural adjustments for altering direction during walking.
Dali Xu1, Les G Carlton, Karl S Rosengren
1Georgia State University, Department of Physical Therapy, GA, USA. phtdxx@langate.gsu.edu
Journal of Motor Behavior
|July 21, 2004
Summary
Humans adjust their walking pattern before turning, with faster speeds triggering earlier anticipatory postural adjustments. These adjustments, including backward and sideward leaning, are influenced by turn angle, pivot foot, and speed.
Area of Science:
- Biomechanics
- Human motor control
- Gait analysis
Background:
- Understanding how humans prepare for directional changes in locomotion is crucial for gait rehabilitation and robotics.
- Previous research has explored gait adjustments during turns, but the precise timing and modulation of anticipatory postural adjustments (APAs) require further investigation.
Purpose of the Study:
- To investigate the kinematic and kinetic adaptations of gait and body configuration prior to directional changes during walking.
- To determine the influence of turn angle, pivot foot selection, and walking speed on anticipatory postural adjustments.
Main Methods:
- Eight young adults walked at normal and fast speeds, executing turns of 0, 45, and 90 degrees using either their left or right foot as the pivot.
- Motion capture (video systems) and force plates were employed to record whole-body center of mass and center of pressure trajectories during the step preceding the turn.
Main Results:
- Anticipatory postural adjustments were observed during the step before the directional change.
- APAs occurred earlier during fast walking compared to normal walking speed.
- Turn angle, pivot foot, and walking speed significantly affected the nature and timing of APAs.
- Participants exhibited backward and sideward body lean on the preceding step in anticipation of the turn.
Conclusions:
- The motor system proactively plans and executes anticipatory postural adjustments based on the intended movement goal.
- These findings highlight the predictive capabilities of the central nervous system in organizing body configuration for efficient and stable gait transitions.