Human Gait Analysis

Gait cycle

sequence of events that occur from initial contact on one foot to the next initial contact of the same foot

what does 1 gait cycle equal to

1 stride

2 steps

cadence

number of steps/time

speed

step length * cadence

stance phase

62%; when foot is on ground

begins with IC and ends when toes lifts off

initial double stance; single limb support; terminal double stance

swing phase

38%; time when foot is in the air

begins with toe-off and ends when heel/foot hits ground

average walking speed

82 m/min

1.36m/s

how to increase walking speed

increase cadence or increase step/stride length

when double stance is omitted

it becomes running

walking faster means

lengthening single leg support and shortening double limb support

antalgic gait

gait avoiding pain

increase swing phase of affected phase to decrease stance phase

ataxic phase

unsteady, staggering gait

healthy gait parameters

stride length: 1.3-1.6m

step length: 0.7-0.8 m

cadence: 100-131 steps/min

foot angle: 5.1-6.8 degrees(TOE OUT)

factors affecting gait speed

stride length is more impactful than cadence

women have greater cadence

increased height leads to increased stride length

what affects gait in the elderly

aging effects on musculoskeletal system

secondary due to aging related to pathological conditions

gait changes in the elderly

decreased walking speed

most due to decreasing stride length

increasing walking base/width due to losing balance so need to increase BOS

reduction in total range of hip flexion/extension

reduction in swing phase knee flexion

reduction in ankle plantar-flexion during push off

gait in children

wider walking BOS(toe out)

shorter stride length

higher cadence but still lower walking speed because of shorter steps

no heel strike(flat foot IC)

reduced stance phase knee flexion(knee extended)

whole leg externally rotated in swing phase

absence of reciprocal arm swinging

stance phase broken down

initial double stance/weight acceptance

• IC

• Loading response

single limb support

• mid stance

• terminal stance

terminal double stance

• pre-swing

swing phase broken down

initial swing

mid swing

terminal swing

initial contact

0-2%

start stance with heel rocker

impacts deceleration

no clear ending

loading response

2-12%

no clear beginning to ends with lift of other foot

shock absorption, stability, preservation of progression(GRF during heel strike)

accepts body weight

mid stance

12-31%

begins with lift of other foot and ends with heel rise of stance foot

COM is the highest

limb and trunk stability; forward progression(over the supporting foot)

terminal stance

31-50%

begins with heel rise of stance foot and ends with IC of the other foot

limb and trunk stability

forward progression(beyond supporting foot)(COM is out of BOS but no fall bc other leg steps to create a new BOS)

pre-swing

50-62%

begins with IC of the other foot and ends with toe off of the stance foot

body weight transferred from trailing to lead limb

obje: position limb for swing; accelerate progression → push-off

initial swing

62-75%

begins with toe off and ends with swing limb roughly aligning with stance limb

obj: foot clearance of the floor to prevent fall; advancement of the limb from its trailing position

mid swing

75-87%

begins with swing limb roughly aligning with stance limb and ends when tibia of swing leg is vertical to ground

obj: foot clearance of the floor; limb advancement

terminal swing

87-100%

begins with vertical tibia and ends with IC of same foot

obj: complete limb advancement; prepare for stance

basic function of gait

engaging lower extremity(locomotor unit) as it carries the passenger unit

passenger unit

head, arm and trunk(HAT)

70% of BW

COM: anterior to T10

locomotor unit

11 articulations: selective control from 57 muscles

functions: stance stability, propulsion/progression; shock absorption; energy conservation(no unnecessary motion)

overlap between passenger and locomotor unit

pelvis: stability and mobility

locomotor: stance stability

upright stability: determined by body alignment and muscle activity

challenges: top heavy passenger unit; multisegmented nature of lower extremities; contours of LE joints

multisegmented natures of the lower extremities

ligamentous joints built for mobility not stability

narrow BOS

no passive stability at ankle

dynamic stability

stand with toe-out angle(BOS wider in the front)

mean stride/step width(7-10 cm)

muscle action to accelerate and decelerate the COM motions

locomotor unit: progression

initial step;

foot rockers: heel; ankle; forefoot; toe

propulsive force

heel rocker

first 12% of GC

preserve forward momentum

ant compartment draws tibia forward(initiating knee flexion) thus activating quads to restrain rate of knee flexion; draw femur forward

why is heel IC ideal

the GRF pushes foot into plantarflexion recruiting dorsiflexors to slow down the motion

ankle rocker

passive DF → restrain by the soleus muscle(pressure in front of ankle and pushes leading PFs to activate for control)

midstance until heel lift

forefoot rocker

by the rounded shape of the metatarsals

toe rocker

anterior medial forefoot and great toe(last one in contact)

propulsive forces for progression

1. forward fall of the body

2. ankle push-off during pre-swing

3. hip flexion(from PSw to MSw); lifting and advancing the swing limb

4. active knee extension during terminal swing

GRF is up and forward

locomotor unit: shock absorption

free fall at IC

mechanisms

1. DF muscles to control ankle PF

2. quads to control knee flexion: largest shock absorption

3. hip ABD muscles for contralateral pelvic drop

locomotor unit: energy conservation

efficiency = work accomplished/energy

mechanisms to conserve energy: COM/COG alignment modulation; selective muscular muscle; minimize movement

COG movements during gait

peaks at midstance(SLS); low at double support

moves in sinusoidal fashion(up and down; side to side)

COM modulation by pelvic motion

transverse/lateral shift(linear): move COG closer to stance foot

transverse-plane rotation(about 5 degrees): move hips closer to midline, increase step length without a lot hip flexion; less side to side fall of COG of HAT

COM modulation by ankle motions

onset of double limb support(HAT COM is lowest)

heel rise(not PF) of stance limb during terminal stance → PF at the beginning of pre-swing

ankle DF of swing limb during terminal swing

reduces overall drop of pelvis

what does increased COM displacement over time lead to

increased COM velocity

increased COM acceleration

increased vertical GRF

VGRF equation

VGRF = m*a + weight

selective muscular control

specific timing, intensity and duration of muscle activations

activations in response to ongoing postural changes(rely on sensory input)