Phases of Gait Flashcards
Name two main phases of gait?
- stance (60-62% of the cycle)
- swing (40 % of cycle)
Name subdivisions of gait and percent
- IC 0 %
- LR 0-12%
- MSt 12-31%
- TSt 31-50%
5 PSw 50-62% - ISw 62-75%
- MSw 75-87%
- TSw 87-100%
Traditional Gait phases
- heel string 0
- foot flat 8
- midstance 30
- heel off 40
- toe off 60
- acceleration
- midswing
- deceleration
Match the RLA to the standard?
- Heel strike
- foot flat
- midstance
- heel off
- toe off
- acceleration
- midswing
- deceleration
- heel strike = IC
- food flat = LR
- midstance = MST
- heel off = TSt
- toe off = preswing
- acceleration = ISW and MSW
- midswing = part of MSW and TSW
- deceleration = TSw
What is the motion of the UE during gait?
upper limb is opposite to LE motion
(LUE forward and RLE forward)
-reciprocal relationship counterrotation b/t shoulder and pelvic girdle
When is double limb support during gait?
- IC/LR
- Preswing
When is maximal knee flexion occur
ISw
how is stride determined
measuring the distance from the point of IC/HS of one LE to the next IC/HS of the same extremity
what is step length?
is IC of one foot to the IC of the opposite foot
how do you determine velocity
cadence (# of steps/min) X step length = distance covered/minute
cadence
steps/min
difference between cadence and length of double support
as cadence increases the duration of double limb support decreases
what is the normal degree of toe out during gait?
7 degrees
how does the normal degree of two-out during gait?
as speed increases, degree of toe out decreases
how does toe out related to the base of support
greater toe out means greater BOS
how does the size of BOS relate to static stability
-larger BOS the greater the stability
what is the relationship of static stability to mobility?
- an inverse relationship
- as one goes up the other goes down
how does the normal pelvic rotation affect the energy requirement of gait?
- apparent lengthening of the LE by pelvic rotation serves to diminish the amount of drop of COM for a given step length
- in order to maintain the same step length but without pelvic rotation, the hips would have to flex and extend farther, production a >excursion of COM
in short, no pelvis rotation makes:
the hip flexors and extenders work more making them farther from the COM
explain how movement of the COG during gait affects the expenditure of energy associated with gait:
Vertical COM: creates work and energy expenditure
Lateral: COM creates linear momentum that must be counteracted by muscular effort and thus creates expenditure of energy
Vertical displacement of COM affects gait how?
creates work and energy expenditure
Lateral displacement of COM affects gait how?
- creates linear momentum
- momentum must be counteracted by muscular effort and thus creates an energy expenditure
How does lack of knee flexion increase energy cost of gait
- compensatory movements
ex: hip hiking to affected side - compensatory mvmts increase vertical displacement of COG
- disrupts interaction between ankle and the knee and transition in stance
During stance, the pelvis drops slightly toward the unsupported side. The interaction of pelvic drop with knee extension at mid stance decrease the energy cost of ambulation. Why?
- the extended stance limb at MSt tends to elevate the COG
- the pelvic drop allows the COM to fall and compensates fro the extended limb which has raised the COG
What effect does the angle of inclination of the femoral neck have on the base of support in the standing position?
it guides the shaft of the femur towards the midline, thus narrowing the BOS
What angle at the knee compensates for the effect of the femur toward the midline in standing?
-physiological values at the knee
when during gait does the knee and ankle motion tend to shorten the stance limb?
- the transition from swing to stance accompanies the transition from a descending to an ascending COG
- to smooth the transition the knee flexes falling IC and the foot PF from IC/LR
- this effectively shortens the limb as the COG starts to rise
When during gait does the knee and ankle motion tend to shorten the stance limb?
-the extension of the knee with PF of the ankle from the MST thru PSW effectively does the reverse; that is apparently lengthens the stance limb to decrease the descent of the COG bc it is now moving downward for its highest elevation at MST
What are the six determinants of gait?
- pelvic rotation in horz. plane
- lateral pelvic tilt (drop to unsupported side)
- knee flexion
- knee with ankle interaction x2 (shortening and lengthening)
- Physiologic valgus at the knee
what are the determinants of gait important for ambulation?
help to minimize vertical rise of COG, prevent excessive dropping of COG, minimize side to side movement of COG and provide smooth transition to the WBing limb.
-all these serve to minimize energy expenditures during normal gait
During which subdivision of gait are the DF of the ankle most active?
IC/LR
What type of contraction are the DF performing in IC/LR?
eccentric
What is the fx of the DF eccentrically contracting during IC/LR?
to prevent the foot form slapping the ground
What joint motion at the ankle is occurring during mid stance?
DF
What type of contraction is the gastric-soleous complex at mid stance?
eccentric
What is the function of the eccentric contraction of the gastroc during mid stance?
to slow DF or stabilize the ankle as the LOG passes in front of the ankle, producing DF moment
Why is the contraction of the quadriceps necessary at initial contact and loading response?
at IC/LR the LOG and the line of force up the limb from the foot striking the ground fall behind the knee joint axis, producing a flexion moment at the knee.
-the quads contract to prevent the knee from buckling
Explain why the hamstring are active during both terminal swing and initial contact?
Hamstrings fx to decelerate the forward swing of the limb and to prevent excessive hip flexion as well as knee extension bc of momentum
-they also serve with Glut Max to stabilize the hip at IC/LR when the body weight is carried on a flexed hip.
What is the function of the gluteus max in the early stance phase of gait?
provides hip control on the stance limb
During which subdivision of gait are the hip flexors most active
initial swing
During initial swing, what are the hip flexors responsible for?
for the initiation of the swing phase
What is the function of the abductor muscles of the stance hip during IC/LR?
-function as lateral stabilizers of the pelvis, preventing excessive lowering of the pelvis on the unsupported side during stance phase
in what fashion do these muscles contract during IC thru MST? (Abductors)
as the pelvis drops, the contraction is eccentric. While the pelvis is stable, the contraction is isometric
In which subdivision of gait are the erector spinal muscle most active?
IC/LR
R > with R HS
What joint motions during gait are primarily caused by momentum?
- Flexion of the humerus at the shoulder,
- completion of flexion of the femur at the hip during swing phase
- extension of the tibia at the knee in stance phase
- DF in stance
- Completion of extension of tibia at the knee in stance phase
- DF of the
Sources of momentum:
the swinging limbs and the push off of the GS from the TST thru MSW
-if walking slowly momentum is lost causing muscles to contract almost continuously
The step length of which limb will be most affected by weakness of left gastric-soleus?
R step length will be shortened because stance on the left will be prematurely terminated
-GS needs to stabilize the ankle when LOG falls anterior to the joint during MST
At which point in the gait cycle will you easily observe the effect of a weak tib anterior?
-IC/LR and swing phase (steppage gait)
What foot and ankle muscles can assist in the action of the weak tib ant.
EDL and EHL
Glut max weakness gait
- lurch
- posterior trunk lurch to keep LOG well posterior to the hip
Glut med weakness
-lateral trunk lurch over stance hip
iliopsoas
-forward thrust of pelvis at ISW
quad weakness
-genu recurvatum at IC/LR or use had to post into extension and bring trunk forward at IC/LR
DF weakness group
-stoppage during swing and foot slap at IC/ LR
Ground reaction force is an example of which newton law?
Law or reaction
during gait, momentum provides considerable force to sustain forward progression, to which newtons laws is momentum most directly related?
law of inertia
1st law:
law of inertia
object will remain at rest unless acted on
law of intertia
2nd law:
law of acceleration
states the object moving is proportional to the unbalanced forces acting on it and inversely proportional to the mass of that object
law of acceleration
F=ma
3rd
law of reaction
states for every action there is an equal and opposite reaction; forces always come in pairs
law of reaction
