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Copy of The Prerequisites of Normal Gait

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Marcus Tang

on 24 March 2015

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Transcript of Copy of The Prerequisites of Normal Gait

Prerequisites of gait
Normal gait has 5 attributes or prerequisites that are frequently lost in pathological gait.
(Perry 1985)
4.Adequate step Length
Adequate body balance
A stable and properly positioned stance side
Adequate hip and knee flexion on swing side
Neutral dorsiflexion,inversion and eversion of the foot on the swing side
What is Gait?
Locomotion on 2 legs (swinging centre of gravity over rigid struts), with 1 foot in contact with ground at all times

Provides support & propulsion

5 prerequisites in gait
1. Stability in stance
2. Swing phase clearance
3. Foot preposition in terminal swing
4. Adequate step length
5. Energy conservation
The Prerequisites of Normal Gait
Essential to daily living –
dynamic adaptation to our environment...
Excellent test of physical activity
Most efficient walking speed is ~3.2 mph (1.4m.s-1 )
~110 steps per minute (cadence)
~3.3 METS - slowest speed walk and gain some health benefits (ACSM)
1MET = 3.5ml.kg.min-1 , 1000ml O2 used = 5kal consumed
80Kg person, 30 minutes, 3.2mph = ~100 Kcal
1.Stability in stance phase
Challenged by 2 major factors:
The body is top-heavy
Center of mass lies above the base of support, just in front of S2 vertebra.
Walking continually alters segment alignment
3.Pre-position of the foot in terminal swing
-The essentials of a normal gait-
When an individual walks, Centre of mass (CoM) remains within the BoS while standing, moves forward with each step from one base of support to another.
The body is constantly altering the position of the trunk in space to maintain balance over the base of support and also balance when moving
The Lower extremity must function to :
Allow advancement of the limb in swing phase
Maintain balance
Provide propulsion
Ensure appropriate position of the structures above.

2.Clearance in swing phase
requires :
Appropriate position and power of the ankle, knee and hip on the stance side
Adequate ankle D/F,Knee Flexion and Hip Flexion on swing side
Stability in stance foot
Adequate body balance (posture, coordination)
Appropriate body balance
Stability, power and positioning on the stance side
Adequate ankle d/f
Balance betwen inverters and everters of foot, appropriate knee and foot position
5. Energy Conservation
Whenever possible :
Joint stability is provided by the ground reaction force in conjunction with ligaments instead of muscles
Centre of Mass (CoM) excursion is minimised in all planes
Muscle forces are optimized
Eccentric muscle forces used to the greatest extent possible during gait
"Stretch energy" in tendons and muscles is returned as kinetic energy, since in normal gait muscles tend to be pre-strecthed before they fire concentrically
Biarticular muscles serve to transfer energy from 1 segment to another.
(Alexander 1992)
Optimizing forces involves :
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