Lecture 1: Gait Flashcards
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
% of gait cycle in stance vs swing
stance = 60%
swing = 40%
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
kinematic variables of gait
sagittal plane = flx/ext
frontal plane = ABD/ADD
trans plane = RT
kenetic variables of gait
forces = vertical, fore-aft, medial-lateral
moments, powers
center of pressure
external forces of gait
produce external torque/moment
i.e. ground reaction forces, gravity, air, resistance, friction
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
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
newtons 3rd law
for every action there is an equal and opposite reaction
components of GRF
vertical
anterior-posterior
medial-lateral
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
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
functional tasks of stance phase
weight acceptance
single limb support
fwd progression
functional tasks of swing
swing limb advancement
foot clearance
objectives of initial contact
start of 1st rocker (heel rocker)
impact deceleration
objectives of loading response
shock absorption
weight bearing stability
preservation of progression
foot flat achieved
ankle during IC
held in neutral by pre tibial mm
knee during IC
full extension (5 deg flexion)
provide stability
hip during IC
peak flexion (20 deg)
positioned for optimal fwd progression and stability
critical event of IC
heel contact
what kind of moment is present at each joint of the LE during IC
hip = flexion
knee = extension
ankle = PF
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
what is happening at the ankle during loading response
pre tibial mm eccentrically control PF (5 deg PF)
subtalar eversion
heel (1st) rocker
what is happening at the knee during loading response
20 deg flex for shock absorption
quads active to control knee flexion moment
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
