Lecture 1: Gait Flashcards by Braden Talbert

traditional vs nachos terminology for all stages of gait

traditional = rancho

heel strike = initial contact
foot flat = loading response
midstance = midstance
heel off = terminal stance
toe off = pre swing
acceleration = initial swing
midswing = midswing
deceleration = terminal swing

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% of gait cycle in stance vs swing

stance = 60%
swing = 40%

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temporal spatial variables of gait

velocity = rate of linear fwd motion (m/sec)

cadence = # steps per unit time (steps/min)

stride length = heel strike to ipsilateral heel strike

step length = heel strike to contralateral heel strike

step width = width of base of support

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kinematic variables of gait

sagittal plane = flx/ext

frontal plane = ABD/ADD

trans plane = RT

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kenetic variables of gait

forces = vertical, fore-aft, medial-lateral

moments, powers

center of pressure

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external forces of gait

produce external torque/moment

i.e. ground reaction forces, gravity, air, resistance, friction

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internal forces of gait

produces internal moment/torque

usually in response to external torque created by GRF

can control or generate movement

possible contributions from ligaments, joint capsules, mm, or bony structures

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newton’s 1st law

every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied

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newtons 3rd law

for every action there is an equal and opposite reaction

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components of GRF

vertical
anterior-posterior
medial-lateral

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describe the vertical component of GRFs

2 peaks: 110% body weight

F1 = at weight acceptance, due to action of body momentum
F3 = at terminal stance, caused by push of ankle PFs against floor in combo with the downward acceleration of COG

1 valley: 80% body weight

F2 = at midstance, created by rise of COG

faster walking speeds created higher peaks and lower valleys

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define moment/torque

potential for a force acting a distance from the axis of RT to produce RT of segment

Units = N x m or kg x m

Torque = Force x moment arm

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functional tasks of stance phase

weight acceptance
single limb support
fwd progression

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functional tasks of swing

swing limb advancement
foot clearance

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objectives of initial contact

start of 1st rocker (heel rocker)
impact deceleration

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objectives of loading response

shock absorption
weight bearing stability
preservation of progression
foot flat achieved

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ankle during IC

held in neutral by pre tibial mm

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knee during IC

full extension (5 deg flexion)
provide stability

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hip during IC

peak flexion (20 deg)

positioned for optimal fwd progression and stability

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critical event of IC

heel contact

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what kind of moment is present at each joint of the LE during IC

hip = flexion

knee = extension

ankle = PF

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muscle activity at hip, knee, and foot at IC

hip = HS and glutes for hip stability

knee = quads for knee stability

foot = pre-tibial to counterbalance PF moment

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what is happening at the ankle during loading response

pre tibial mm eccentrically control PF (5 deg PF)

subtalar eversion

heel (1st) rocker

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what is happening at the knee during loading response

20 deg flex for shock absorption

quads active to control knee flexion moment

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what is happening at the hip during loading response

maintained in flexion (20 deg) hip extensors active to stabilize

moments of the LE at loading response

hip = flexion knee = flexion ankle = PF

mm activity at hip, knee, and ankle during loading response

hip = HS and glutes for hip stability knee = quads to counterbalance flexion moment ankle = pre-tibial to counterbalance PF; calf for stance stability

objectives of midstance

progression over stationary foot limb and trun stability

terminal stance objectives

progression of body beyond supporting foot trunk and limb stability

what is happening at the ankle during midstance

DF controlled eccentrically by gastric and soleus (CRITICAL EVENT) ankle (2nd) rocker

what is happening at the knee during midstance

extension

what is happening at the hip during midstance

neutral

external moments of the joints of the LEs during midstance

hip = extension knee = extension ankle = DF

mm activity at the hip, knee, and ankle during midstance

hip = none knee = quads for stance stability ankle = calf for stance stability and to counterbalance DF moment

what is happening at the ankle during terminal stance

noted by heel rise (trailing limb = critical event!) forefoot (3rd) rocker decline in gastric/soleus mm activity

what is happening at the knee during terminal stance

full ext to max step length

what is happening at the hip during terminal stance

20 deg apparent hyperext for max step length

external moments of the LE during terminal stance

hip = ext knee = ext Ankle = DF

mm activity of hip, knee, and ankle during terminal stance

hip = none knee = none ankle = calf to counterbalance DF moment

pre-swing objective

position of limb for swing accelerated progression

initial swing objective

foot clearance advancement of limb from trailing limb position

midswing objective

limb advancement foot clearance

terminal swing objective

complete limb advancement prepare limb for stance

what is happening at the ankle during pre swing

2nd arc of PF (15 deg) toe rocker no gastroc/soleus activity

what is happening at the knee during pre swing

passive knee flexion (CRITICAL EVENT) prepares limb for toe clearance

what is happening at the hip during pre swing

10 deg apparent hyper extension

external moments of the LE during pre swing

hip = ext knee = flx ankle = DF

mm activity of hip, knee, ankle during pre swing

hip = hip flexors to counterbalance extensor moment and initiate swing knee. = no mm activity ankle = calf to counterbalance DF moment (early) and pretrials for foot clearance (late)

what is happening at the ankle during initial swing

nearly neutral

what is happening at the knee during initial swing

peak flexion (60 deg) for toe clearance - CRITICAL EVENT peak mm activity of biceps femoris SH, sartorius, and gracilis

what is happening at the hip during initial swing

15 deg flexion - CRITICAL EVENT peak mm activity of gracilis and sartorius

what is happening at the ankle during midswing

neutral to slight DF - CRITICAL EVENT

what is happening at the knee during midswing

passive extension caused by momentum of hip flexion

what is happening at the hip during midswing

peak flexion 25 deg

what is happening at the ankle during terminal swing

at natural to prepare for heel strike

what is happening at the knee during terminal swing

extension to neutral (5 deg flex) - CRITICAL EVENT ext controlled eccentrically by HS quads turn on in late terminal swing to prepare for weight bearing

what is happening at the hip during terminal swing

subtle retraction to 20 deg of flexion

pelvis motion in sagittal plane during gait

netral pelvis = 10 deg anterior tilt slight increase in ant pelvic tilt during terminal stance and terminal swing

pelvis motion in frontal plane during gait

during WA, 4 deg contralateral pelvic drop during pre-swing 4 deg ipsilateral pelvic drop

pelvis motion in transverse plane during gait

max pelvic protraction (4 deg) during terminal swing and IC max pelvic retraction (4 deg) during terminal stance netral RT at midswing and midstance

trunk movement during gait

avg vertical displacement = 4.2 cm avg lateral displacement = 4.5 cm to R and L multifidus acts B during IC low level of rectus abdominis and external obliques

describe UE movement during Gait

arms provide counterforce to oppose excessive RT of body peak flexion (shoulder = 8 deg) during contralateral IC - passive movement peak ext (shoulder = 24 deg) during ipsilateral IC- posterior deltoid and teres major arm swing range (increased ext) increased with increasing walking velocity

critical joint angles/timing for the ankle

neutral ankle during swing 20 deg DF in terminal stance

critical joint angles/timing for the knee

60 deg flexion in initial swing 20 deg flexion in loading response 0 deg in initial contact and midstance

critical joint angles/timing for the hip

25 deg flexion in midswing 20 deg extension in terminal stance

critical mm activity at ankle during gait

anterior tib during loading response (eccentric) anterior tip during swing (concentric) gastroc during stance (eccentric); turns off in preswing

critical mm activity at knee during gait

no HS or quad mm activity during midswing quads active during stance to control knee flexion moment

critical mm activity at hip during gait

hip flexors during swing (concentric) hip abductors active during single limb support to prevent hip drop