KINETIC ANALYSIS OF GAIT INITIATION D. Gordon E. Robertson, PhD, FCSB 1 Richard Smith, PhD 2 Nick O’Dwyer, PhD 2 1 Biomechanics Laboratory, School of Human Kinetics, University of Ottawa, Ottawa, Canada 2 Biomechanics Laboratory, School of Exercise and Sport Science, University of Sydney, Sydney, Australia
KINETIC ANALYSIS OF GAIT INITIATION. D. Gordon E. Robertson, PhD, FCSB 1 Richard Smith, PhD 2 Nick O’Dwyer, PhD 2 1 Biomechanics Laboratory, School of Human Kinetics, University of Ottawa, Ottawa, Canada 2 Biomechanics Laboratory, School of Exercise and Sport Science, - PowerPoint PPT Presentation
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KINETIC ANALYSIS OFGAIT INITIATION
D. Gordon E. Robertson, PhD, FCSB1
Richard Smith, PhD2
Nick O’Dwyer, PhD2
1Biomechanics Laboratory,
School of Human Kinetics,
University of Ottawa, Ottawa, Canada
2Biomechanics Laboratory,
School of Exercise and Sport Science,
University of Sydney, Sydney, Australia
Introduction
Gait initiation usually consists of the period between quiet stance and steady-state gait. In most cases, it takes only 2 steps to reach steady-state. The leg that lifts first will be called lead-leg; the other leg will be the trail-leg. There are many studies that have documented the paths of the centres of pressure, the motion patterns and EMGs but very few studies which have computed inverse dynamics or moment powers.
Purpose
To examine the patterns of the moments of force and their powers of the lower extremities during gait initiation.
To determine the sequence of events required to initiate gait from quiet stance.
To observe whether similar patterns occur with a variety of subjects.
Methods
• Seven subjects performed five trials starting with their right leg
• Started with each foot on a separate force plate and stepped “briskly” to two other force plates and then continued several steps onto the floor
• Video taped at 200 fps, forces sampled at 1000 Hz using a Motion Analysis, EVaRT system
• 42 markers tracked to make 13-segment, 3D model
• Inverse dynamics and powers computed by Visual3D
Initiation of Gait: Events
Quiet stanceQuiet stance First toe-off(lead-leg)
First toe-off(lead-leg)
Second toe-off(trail-leg)
Second toe-off(trail-leg)
Results
• movements started approximately 1 to 1.5 seconds before trail-leg toe-off
• greatest variability and least movement occurred in first 0.5 seconds (loading phase of lead, unloading of trail) called Phase 1
• after Phase 1, consistent patterns of moments and powers began
Notice that as the combined centre of pressure moves backwards and towards the lead-leg the line of gravity proceeds forwards and towards the trail-leg. The line of gravity is outside the base of support shortly after the lead-leg lifts.
Notice that as the combined centre of pressure moves backwards and towards the lead-leg the line of gravity proceeds forwards and towards the trail-leg. The line of gravity is outside the base of support shortly after the lead-leg lifts.