Human LocomotionHuman Locomotion

Phases of the Gait Cycle

And

Determinants of Gait

Understanding the Phasic Understanding the Phasic Characteristics of GaitCharacteristics 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

Basic Gait Phase TerminologyBasic 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

Phases of the Gait CyclePhases of the Gait Cycle

How would you define the Phases of the Gait Cycle ?

Phases of the Gait CyclePhases of the Gait Cycle Stance Phase

– Initial Double Support– Single Support– Terminal Double

Support

Swing Phase– Initial Swing– Terminal Swing

Gait Cycle

Stance Swing

DS DSSSISw TSw

Phases - Percentage of Gait Phases - Percentage of Gait CycleCycle

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

Gait EventsGait Events Support Events

– Foot (Heel) Strike– Foot Flat– Midstance– Heel Off– Foot (Toe) Off

Swing Events– Foot (Toe) Off– Midswing– Foot (Heel) Strike

Gait EventsGait EventsFoot (heel) StrikeFoot (heel) Strike

Initial Contact

Beginning of Loading

Foot Position may vary, but is generally supinated

Represents end of single support on the opposite side

Gait EventsGait EventsFoot FlatFoot 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

Gait EventsGait EventsMid-StanceMid-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

Gait EventsGait EventsHeel-OffHeel-Off

Un-loading of limb and preparation for swing

Foot Strike on Opposite Side

Weight Shift to opposite side begins

Gait EventsGait EventsToe-OffToe-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

Gait EventsGait EventsMid-swingMid-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

Gait EventsGait EventsTerminal SwingTerminal 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

How do we How do we ManipulateManipulate Walking VelocityWalking Velocity

How do we How do we ManipulateManipulate Walking VelocityWalking Velocity

Stride LengthCadence

Manipulation of Velocity– Initial Adjustment - – Secondary Adjustment

Why do we walk the way we do????Why do we walk the way we do????

Human Gait

Considerations:Considerations:

AnatomyManipulation of Objects VisionSpeedEfficiency

EfficiencyEfficiency

Movement Requires Force

Work = Force x DistanceIncreases in force and/or

distance reflect increased work

Amount of Work Determines Energy Expenditure

EfficiencyEfficiency

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

EfficiencyEfficiency

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

** Efficiency **** Efficiency **Factors Determining Energy CostFactors 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

Pelvic RotationPelvic Rotation

Pelvic Lateral TiltPelvic Lateral Tilt

Knee Flexion During StanceKnee Flexion During Stance

Ankle MechanismAnkle MechanismPlantar FlexionPlantar Flexion

Lengthens the leg during stance

Ankle MechanismAnkle MechanismDorsiflexionDorsiflexion

Lengthens Leg During Swing, prior to foot contact

Step WidthStep Width

Narrowing the base during double stance reduces lateral motion