1. Progression
2. Stability (postural control)
3. Adaptation

** gait is a dynamic balancing activity **

rhythmic patterns of mm activation advance the body in the desired direction

altering gait pattern to meet demands of the environment

can negotiate obstacles that visually we can see ahead of time (anticipatory)

and ability to respond (reactive)

Using these 3 factors of gait

allow for:

1. initial contact (heel contact)
2. loading response (foot flat)
3. midstance
4. terminal stance (heel off)
5. preswing (toe off)

Control of Normal Gait:

Swing phase

40 % of gait cycle - part of gait where foot is OFF the ground

initial (acceleration), midswing, and terminal (deceleration) swing

Double support

Single support

occurs during first (initial contact and loading response) and last 10%(pre-swing) stance phase

occurs when opposite limb is in swing phase

go over normal jt motion requirements

look at notes/critical elements

table format in notepack

Distance and Temporal Factors

of Gait

Step length = one initial contact to initial contact of the other foot (normal 76.3cm/30 inches)

Stride length = distance from one heel strike to the same LEs heel strike

Step width = center of one heel to center of other heel (7-9cm)

number of steps per unit of time

112 steps per min or 1.9 steps per sec

1.46 m/s or 3.26mph = normal/healthy speed

minimal energy expenditure

very quantifiable

Distance and Temporal Factors

How would you measure these in the clinic?

damp feet, baby powder, on black paper

pedometer

moving up and down - 2 sinusoidal waves per gait cycle

look at the person from the side and look at their head moving up and down

most = midstance

least = heel strike

look at head and see how much is moving left and right about 2cm in each direction

happens during midstance if on right foot then 2cm that way and vice versa for left

1 sinusoidal wave pattern per gait cycle

Strategies to minimize energy expenditure:

vertical displacement is minimized by

4 things

1. horizontal pelvic rotation = 5 degrees of pelvis rotation forward and increases the relative leg length and minimizes the downward displacement of the COM

2. lateral pelvic tilt - at midstance contra pelvis drops in frontal plane to lower body and minimize upward displacement of COM

3. knee flx during stance and swing phases - knee flx during stance limits max vertical excursion of COM. During swing, knee flx shortens leg allows for foot to clear and minimize upward displacement of COM

4. ankle rotation - DF/PF to make contact with the ground and elongate the limb (minimizing downward displacement)

lateral pelvic/hip motion

Muscle activation patterns during Normal Gait:

Hip Extensors

Hip = ext, flx, abd

extensors = glute max in terminal swing (eccentric activation to decelerate the forward motion of the limb in preparation for initial contact)

initial contact to midstance (concentric activation to ext the hip to neutral)

Late stance = concentric burst of activity to propel the body forward

Control of normal gait mm activation:

Hip Flexors

iliopsoas, sartorius, rectus femoris

terminal stance = eccentric to control the hip extension

Preswing to initial swing = concentric activation to bring the limb forward because hip is moving from ext to flx

During 2nd half of swing phase hip flexion is generated by momentum of the leg. Controlled by eccentric activation of the hip extensors.

glute med and min

During single limb support: 

strong eccentric ipsilateral activation to control the opposite pelvic drop

Loading response = controlled knee flexion eccentric activation as knee moves from 0 - 15 degrees of flx for shock absorption

Midstance = concentric to straighten knee and support the body weight

Preswing = eccentric activiation to control knee flx

Muscle activation patterns during normal gait:

knee flx

Muscle activation patterns during normal gait:

Ankle PF

Loading response to midstance = eccentrically to control forward motion of the tibia (15 of PF to 10 of DF)

Terminal stance = concentric to propel the body forward

Muscle activation patterns during normal gait:

Ankle DF

Initial contact to loading response = eccentric control PF because the ankle is at 0, foot is lowered to the ground

Swing phase = concentric contraction clears the foot during swing

neural network in the lumbosacral spinal cord produces rhythmic LE stepping

- have a flx and ext circuit

- could be important in spinal cord patients

- body weight supported treadmill training

descending information

- mesencephalic locomotor region

- reticulospinal pathway is used to initiate reciprocal walking

- cerebellum helps to refine mvmts by fine tuning walking via error detection and correction. Thus a lesion here would result in an ataxic gait pattern.

muscle spindle - hip flexors are reflexively activated by increased step length - helpful in treadmill training - 1A afferents are stretched to reflexively move the LE

GTO - during stance phase - 1B afferents to fire, actually activates the agonist mm group

Adaptive (react) strategies for modifying gait

Anticipatory (proactive) strategies for modifying gait

1. momentum
2. gravity

Abnormal Gait:

Motor impairments

gait deviation and resulting compensation

Abnormal tone - spasticity (lengthened) because of over activity of the stretch reflex

- can lead to gait deviation (agonist & antagonist)

During stance

foot flat or forefoot - no heel strike (where is the ground reaction force now) in front of the knee so knee hyperextends and you get a forward trunk lean and individual might compensate with a shortened step length

PF Hypertonia

during swing

impairment = toe drag

compensation (possible) = vaulting (raising up higher on the opposite foot), circumduction, hip hiking, contralateral limb lean

PF Hypertonia

swing and initial contact

initial contact is made with the lateral border of foot - due to excessive PF and posterior tibialis activity (equanovarus foot)

excessive PF and peroneus brevis activity leads to initial contact with medial border of foot (equanovalgus foot)

impairment = quads fire during loading so knee is not shock loading

compensation = hyperextension of the knee and the trunk leans forward as well

Initial contact phase = (excessive activity results in knee flexion at initial contact)

increases demand of quads to control the knee and it could lead to buckling

Compensation = shorter step length and get off of leg really fast, crouched gait

Adductor Hypertonia

hip flexor stiffness

stance phase = causes contralateral pelvis to drop

swing phase = medial displacement of leg = more narrow gait pattern = scissoring gait

Compensation = knee flexes to bring pelvis into alignment

Abnormal Gait:

weakness/paresis

PF weakness

DF weakness

PF weakness = terminal stance (decrease in heel rise)

Compensate with knee hyperextension

DF weakness = forefoot or flat foot contact or foot could hit the floor rapidly/slap floor

Compensation = ipsilateral circumduction, hip hiking, contra vaulting, contra trunk lean

loading = poor knee control and they could buckle, destabilize the knee

Compensation = knee hyperextension and forward trunk lean to prevent from buckling

only need 2+ strength in hip flx for gait

Swing phase = lose hip flx momentum then you automatically lose knee flx, so no adequate foot clearance

Compensation = posterior trunk lean, circumduction, contra trunk lean, contra vaulting

stance = forward trunk lean

Compensation = posterior trunk lean, hang on hips

stance = drop in pelvis on opposite side - the other side is the weak one, not the side that is dropped but rather the lifted side(trendelenberg drop in pelvis due to contralateral weakness)

Compensation = leaned over the non-drop side, rather the weak side that is raised.

Somatosensory deficits - compensate by relying more on vision 

Visual deficits - compensate by walking slower no anticipatory postural control

Vestibular deficits - compensate by walking slower

neglect = left side more common - big safety risk

Impaired memory or poor attention = trip over things, issues with gait initiation, greater risk for falling

affects gait in a shortened AND lengthened position while abnormal tone is just a

lengthened position