Gait
-Pattern of movement of the limbs of animals during locomotion over a solid substrate
Why study gait?
-It involves the interaction of multiple joint movements
-It is dynamic
-It is a test of sensory-motor integration
-It requires adaptation
Insight on:
-Surgical decision making, prosthetic design, orthotic design
What does gait involve?
-a minimum of 11 joints
-involves 57 muscles in pelvis and LE alone
Normal gait
-Efficient
-Adaptable
-Energy efficient
-Changes during lifetime
Pathologic gait
-Not energy efficient
-Not adaptable
-Results in compensatory movement
Traditional Gait
-More applied accepted
Rancho Los Amigos Rehabilitation Center
-more clinically accepted
Rancho los Amigos Gait Analysis
-Describes specific phases of gait
-Specifies ROM at pelvis and LE joints
-Specifies muscle activity at pelvis/LE joints
-Describes muscle contraction
-Describes gait according to "reference" limb
-Performed distal to proximal
Step Length
-Linear Distance
-How far one foot travels during gait cycle
-measured from initial contact of one foot to initial contact of the other foot
2 steps =
1 stride
Stride
-Linear distance
-how far body travels during one gait cycle
-measured by initial contact of one foot to the next initial contact of the same foot
Step Width
-linear distance
-measured from center of posterior heel of one foot to center of posterior heel of opposite foot
-Normal: 2-4
Toe Out
-Angle of line of progression and longitudinal axis
-normal value: 70 (adults)
Cadence
-Number of steps within specific time frame
-Measured as # of steps/minute
normal values:
women: 117 steps/min
men: 111 steps/min
average: 113 steps/min
Speed
-Speed of ambulation on smooth surface
Increase velocity = decrease total stance/swing time
Functional Division of the Body for Gait
Two units
Passenger
Locomotor
Passenger Unit
-Passive
-Alignment important
-HAT:
Head/neck
Arms
Trunk/pelvis
-Arm swing
Not essential for normal gait
Locomotor Unit
-Active
-Carries HAT
-Pelvis and Les
Traditional Gait
Stance Phase:
-Heel Strike
-Foot flat
-Mid Stance
-Heel Off
-Toe Off
Swing Phase:
-Acceleration
-Mid Swing
-Negative acceleration
4 Functions of lower body
-Generate propulsive force
-Maintain upright stability
-Reduce impact shock
-Conserve energy
Heel Rocker
-Essential to LR
-progression of stance limb
-calcaneus to middle of ankle joint
-pretibs control foot to:
decelerate movement
pull tibia forward
assists with knee flexion
Ankle Rocker
-Essential to midstance
-gastroc/soleus control:
forward mov't of tibia
prevent tibial collapse
-ankle moves toward DF
Forefoot Rocker
-Essential to TSt
BW shifted MET heads
Heel rises
strongest torque
strongest propulsive force
gastroc/soleus active
-Component of PSw
passive event
opposite limb creates momentum
Base for accelerated limb adv
Trunk Activity through Cycle
-Extensors:
-bilateral contraction of loading response
-ipsilateral contraction at pre-swing
Abdominals
-Obliques active throughout gait cycle
-Rectus abdominus primarily at MSw, TSw
Trunk Rotation---> Arm swing
Balance
-ability to maintain equilibrium in a gravitational field by keeping or returning the center of body mass over its base of support
Human Balance
Maintained through a complex system involving:
-Sensory Detection
-Sensory Integration
-Musculoskeletal Execution
Systems involved in Balance
-Visual
-Somatosensory
-Vestibular
Visual system
-Provides information about body position relative to environment and moving environment
-Most sensitive to lower frequency
-More processing in movement
Somatosensory System
Peripheral receptors:
-Detects motion of the body with respect to the supporting surface
-Detects motion of the body segments with respect to each other
Vestibular System
-Maintains upright vertical body alignment
-Slowest of all afferent systems
-Acts as reference with conflicting inputs
Postural Control
-the task of controlling the body's position in space for the dual purposes of stability and orientation.
-Limits of Stability
-Base of Support
-Sway
--Sway Velocity
Base of Support
-Feet, can go out further and back further
Postural Sway
-Sway velocity
-CoM, CoP, CoG, BoS
Relationships
Ankle Strategy
-Inverted Pendulum
-Used during quiet stance or in response to small/slow perturbations
-Seen in NORMAL ant/post sway
Hip/Knee Strategy
-response moderate perturbation
*ankle not effective
-Also used in slippery surfaces
-Lowers COM (center or mass)
Stepping Stretegy
-Used when lower extremity (hip/ankle) cannot maintain the COM within BOS
-Steps realigns the CoM within the BoS