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
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KINETIC ANALYSIS OF GAIT INITIATION D. Gordon E. Robertson, PhD, FCSB 1 Richard Smith, PhD 2 Nick ODwyer, PhD 2 1 Biomechanics Laboratory, School of Human.
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KINETIC ANALYSISOF GAIT 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. Leg that lifts first will be called lead leg other leg is trail leg. There are many studies that have documented the paths of the centres of pressure, the motion patterns and EMGs but there have been 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 sequence of events required to initiate gait from quiet stance.
To observe whether similar patterns occur with a variety of subjects.
Methods
• Seven subjects, five trials starting with preferred leg, than five trials with other leg
• Started with each foot on a separate force plate and stepped to two other plates and then several steps onto floor (4 force plates)
• Video taped at 200 fps, forces at 1000 Hz using Motion Analysis, EVaRT system
• 42 markers to make 13-segment 3D model of body
• Inverse dynamics done by Visual3D
Initiation of Gait Events and Phases
Quiet stanceQuiet stance First (lead) toe-offEnd phase 2
First (lead) toe-offEnd phase 2
Third toe-offEnd phase 3Third toe-offEnd phase 3
Results
• movements started approximately 1.5 seconds before toe-off of trail leg (start of Phase 4)
• greatest variability and least movement occurs in first 0.5 seconds (loading phase of lead, unloading of trail) called Phase 1
• afterwards consistent patterns of moments and powers begin
Notice that as the combined c. 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 after the lead-leg lifts.
Notice that as the combined c. 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 after the lead-leg lifts.