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Human Locomotion Phases of the Gait Cycle And Determinants of Gait.

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Presentation on theme: "Human Locomotion Phases of the Gait Cycle And Determinants of Gait."— Presentation transcript:

1 Human Locomotion Phases of the Gait Cycle And Determinants of Gait

2 Understanding the Phasic Characteristics of Gait Provides a logical framework for discussion of gait Provides a logical structure for analyzing gait Provides a common set of terms for communicating information about gait

3 Basic Gait Phase Terminology Gait Cycle Stance and Swing Stride Length - units? Step Length - units? Stride (gait) Width Stride Time –Stance Time –Swing Time Cadence Velocity

4 Phases of the Gait Cycle How would you define the Phases of the Gait Cycle ?

5 Phases of the Gait Cycle Stance Phase –Initial Double Support –Single Support –Terminal Double Support Swing Phase –Initial Swing –Terminal Swing Gait Cycle StanceSwing DS SS ISw TSw

6 Phases - Percentage of Gait Cycle Normal Walking –Stance - 60 % of the Complete Gait Cycle Single Stance – 30% - 40% Double Stance - 20% - 30% –Swing - 40 % Slow/Fast Walking –Slow – Stance Phase percentage Increases –Fast – Stance Phase percentage decrease –Pathological Gait – generally, stance phase percentage increases Double support increased

7 Gait Events Support Events –Foot (Heel) Strike –Foot Flat –Midstance –Heel Off –Foot (Toe) Off Swing Events –Foot (Toe) Off –Midswing –Foot (Heel) Strike

8 Gait Events Foot (heel) Strike Initial Contact Beginning of Loading Foot Position may vary, but is generally supinated Represents end of single support on the opposite side

9 Gait Events Foot Flat Maximum Impact Loading occurs Controlled by the Ant Tib Foot rapidly moves into pronation Weight has been shifted to the support leg Coincides with end of the Initial period of Double Support on the Opposite side

10 Gait Events Mid-Stance Single Support Balance Critical All weight supported by single leg Foot remains pronated initially then re-supinates Late mid-stance is the period of max propulsion Swing occurring on opposite

11 Gait Events Heel-Off Un-loading of limb and preparation for swing Foot Strike on Opposite Side Weight Shift to opposite side begins

12 Gait Events Toe-Off Weight transition to opposite side completed Hip flexion has been initiated to facilitate swing Coincides with beginning of single support on the opposite side

13 Gait Events Mid-swing Leg shortened (ankle dorsiflexion) and hip elevated (abducted) to facilitate swing Mid-stance on the opposite side C. Of G. directly over opposite supporting foot

14 Gait Events Terminal Swing Hip flexion stopped and knee extended via Mo Foot supinated and positioned for foot strike Coincides with the end of the second DS phase on the opposite side The Sequence Begins Again

15 How do we Manipulate Walking Velocity

16 Stride Length Cadence Manipulation of Velocity –Initial Adjustment - –Secondary Adjustment

17 Why do we walk the way we do???? Human Gait

18 Considerations: Anatomy Manipulation of Objects Vision Speed Efficiency

19 Efficiency Movement Requires Force Work = Force x Distance Increases in force and/or distance reflect increased work Amount of Work Determines Energy Expenditure

20 Efficiency Non-functional Movement of the C. of G. is Energy Expensive !!!

21 Efficiency Movement of the Body’s Center of Gravity Reflects Collective Movement of the Body Thus Minimizing the Movement of the Body’s Center of Gravity during Locomotion is the Major Factor in Minimizing the Body’s Expenditure of Energy

22 ** Efficiency ** Factors Determining Energy Cost Determinants on Gait: (Saunders, Inman, Whittle, etc.) –Knee Flexion During Stance –Pelvic Rotation (transverse plane) –Pelvic Lateral Tilt (Obliquity) –Ankle Mechanism (Dorsiflexion) –Ankle Mechanism (Plantarflexion) –Step Width

23 Pelvic Rotation

24 Pelvic Lateral Tilt

25 Knee Flexion During Stance

26 Ankle Mechanism Plantar Flexion Lengthens the leg during stance

27 Ankle Mechanism Dorsiflexion Lengthens Leg During Swing, prior to foot contact

28 Step Width Narrowing the base during double stance reduces lateral motion

29


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