Biomechanics of Gait Walking E. Muybridge

Biomechanics of Gait Walking Applications Walking as a Critical Fundamental Movement Pattern Walking as a Recreational Activity Walking as a Modality for Rehabilitation Walking as a Competitive Sport Influence of Injury/Disease/Disability on Walking Aging Effects on Walking and Implications Independence Footwear Issues Energy Cost E. Muybridge

Describing the Gait Cycle Biomechanics of Gait Walking Describing the Gait Cycle Characteristics of Walking Cyclic Universal Pattern Bi-laterally symmetric Range of Speeds Adaptable to Varied Surfaces Efficient

Describing the Gait Cycle Biomechanics of Gait Walking Describing the Gait Cycle Phases of the Gait Cycle Stance Phase Initial Double Limb Support Single Limb Support Terminal Double Limb Support Swing Phase Initial Swing Terminal Swing

Biomechanics of Gait Walking When we walk, what must happen ?? Control Forces Produce Resist Dissipate

Biomechanics of Gait Walking Objectives Control Forces Maintain Balance

Biomechanics of Gait Walking Objectives Resist/Dissipate Forces Maintain Balance Move Body in Intended Direction

Biomechanics of Gait Walking Objectives Resist/Dissipate Forces Maintain Balance Move Body in Intended Direction Conserve Energy

Biomechanics of Gait Walking Produce/Resist /Dissipate Force Source of Forces Gravity Muscle Contraction Inertia Direction of Forces Vertical Fore/Aft Medial Lateral Magnitude of Forces .1 to 1.2 BW’s

Biomechanics of Gait Walking Produce/Resist /Dissipate Force Forces produce moments (torques) that…. Cause rotations – Total Body Joint Segment

Biomechanics of Gait Walking Maintain Balance Walking……..a series of catastrophes narrowly averted…… The Issues – Dynamic Movement Influenced by external factors Single versus Double Support Depends on Multiple Systems Adaptations in Base of Support

Biomechanics of Gait Walking Move Body in Intended Direction Re-Positioning of Center of Gravity Re-Positioning of Limb Segments Force Production applied to the ground

Biomechanics of Gait Walking Conserve Energy The Six Determinants of Gait (Inman, et. al.)

Biomechanics of Gait Walking The Six Determinants of Gait Underlying Concept Energy Expenditure = Work Done Work = Force x Distance Force = Mass x Acceleration Therefore – the amount of energy we expend is directly related to the amount of mass we move and the extent and speed of movement

Biomechanics of Gait Walking Determinants of Gait Pelvic Rotation – transverse plane Lateral Pelvic Tilt – frontal plane Knee Flexion – during stance Ankle PF - at Toe Off Ankle DF – at Foot strike Gait Width – frontal plane

Biomechanics of Gait Walking Role of Foot Motion Objectives To aid in force dissipation To provide a mobile adapter To provide a rigid lever for propulsion Mechanism - Sub-talar Joint Motion A Tri-planar motion PF and DF Inversion/Eversion AB/ADduction

Biomechanics of Gait Walking At Ground Contact Lateral Side Medial Side Contact Made on the Lateral Border of the Heel Foot is Supinated Foot is Rigid

Biomechanics of Gait Walking Early Stance to MidStance Lateral Side Medial Side Foot is Pronated Foot is Mobile (flexible) Enhances Balance

Biomechanics of Gait Walking Late Stance to Toe-Off Lateral Side Medial Side Foot is Supinated Foot is Rigid Enhances Propulsion

Biomechanics of Gait Walking Pronation/Supination Issues: Too Little – Loss of force dissipation Loss of Mobility – Balance Stress Injury Too Much Relationship to Tibial Rotation Associated Patellar Tracking Issues Soft-Tissue Stress Control of Pronation/Supination Shoe Design Orthotics Muscle Strengthening – Posterior Tib

Biomechanics of Gait Running

Biomechanics of Gait Running As a component of competitive sport As a recreational activity As a stage of motor development As a cause of injury

Biomechanics of Gait Running Differences between walking and running Velocity - Greater range than walking Kinematic Parameters - Increase in most Kinetic Parameters - Increase in some Energy Cost - Generally greater Phasic Differences…….

Biomechanics of Running Differences Between Walking and Running Always a Double Support Phase No Flight Phase Walking

Applied Biomechanics Biomechanics of Running Differences Between Walking and Running Always a Double Support Phase No Flight Phase Walking Running - Never a Double Support Phase Always a flight Phase Running

Running What’s Involved? Project body vertically/horizontally Sufficient vertical/horizontal impulse Flight Dissipate impact Appropriate vertical/horizontal impulse Maintain balance in single support Re-position limbs

How is Propulsion Produced? Propulsive Force Segment motion Newtons 3rd Transfer of Momentum Free leg Arms

How is Momentum Dissipated? Foot Mechanism Ankle Mechanism Knee Mechanism Shoe Mechanism Surface Mechanism

Walking/Running Forces GRF Differences

Ground Reaction Forces in Running GRF’s Influenced by Velocity Vertical Displacement Shoes Surface GRF’s Influence Foot Pressures Joint Forces Joint Moments Impact Shock

Braking/Propelling GRF in Running

M/L GRF in Running

Running - Joint ROM Adaptations Ankle Increased PF/DF Increased pronation/supination Knee Increased flexion in early stance and swing Hip Increased flexion and extension Pelvis Increased transverse plane rotation Arms Increased shoulder ROM Increased elbow flexion

RearFoot Motion in Running Sub-talar Joint Motion Increases duration of impact - facilitates dissipation of momentum Locks/un-locks mid-foot - adaptation to terrain Provides rigidity for propulsion Dynamic Measurement - rearfoot angle Relationship between calcaneus and shank ***FootTrak***

Rearfoot Motion - Too Much…Too Little

Running Shoes Issues

Biomechanics of Running Issues? Surface/Shoe Cushioning.. Versus.. Energy Cost The Problem !!!

Biomechanics of Running Issues? What Factors Influence Speed ??? Speed = Stride Length x Stride Rate Stride Length Anthropometric Factors Strength Flexibility Neuromuscular Factors Stride Rate Neuromuscular Factors Technique Can Running Speed be Improved ??? Yes !!!!!!!

Biomechanics of Running Issues? What Factors Influence Energy Cost ??? Speed Vertical Displacement “Extra” Motion Optimum Stride Length…Stride Rate Relationship Can Running Efficiency be Improved ??? Yes……..but!

Injuries – A Biomechanical Origin Biomechanics of Running Issues? Injuries – A Biomechanical Origin Most running injuries have a biomechanical origin !! Issues – Force Inability to dissipate force Repetition