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Semester 2 FS Exam 10 > Normal and Pathological Gait > Flashcards

Normal and Pathological Gait Flashcards

1
Q

Define Gait

A

the manner or style of locomotion involving the use of two legs, alternatively, to provide support and propulsion, while at least one foot being in contact with the ground at all times.

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2
Q

Important aspects of gait - definition info

A

During gait you are always in double or single support (one leg is in contact with ground at all times) (running = one foot off the ground)
normal gait has general characteristics but is specific to how you walk (unique)

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3
Q

two purposes of the legs during gait

A
  1. prevent collapse

2. propel yourself in the direction of motion

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4
Q

What is the purpose of gait?

A

to transport the body safely and efficiently across the ground (from point a to point b)
efficiency is key! walking for exercise = goal to walk to burn calories; not efficient

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5
Q

Purpose of gait on different surfaces

A

level: how much mass is transported how far? (mass x distance = work)
Uphill/downhill: consider change of altitude, PE = mgh
uneven terrain: safety (NM control, prevent from collapse, balance of upper body, foot trajectory clearance)

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6
Q

5 Major motor functions during gait

A
  1. Support of upper body
  2. Dynamic balance
  3. Foot trajectory control
  4. Generation of mechanical energy
  5. Absorb mechanical energy
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7
Q

Support of upper body

A

prevent collapse of lower limb during stance

upper body needs to be controlled so visual and vestibular systems can work during gait

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8
Q

Dynamic balance

A

maintenance of upright posture and balance of the entire body
important because sensory information can override locomotive system

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9
Q

Foot trajectory control

A

to achieve safe ground clearance and gentle toe or heel landing (toe off to heel contact)

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10
Q

generation of mechanical energy

A

maintain or increase forward velocity
mechanical energy required for every step of gait
generating energy = concentric contraction

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11
Q

absorb mechanical energy

A

shock absorption and stability or to decrease forward velocity of the body (occurs at every joint, especially the knee)
absorbing energy = eccentric contraction

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12
Q

Spatial and temporal descriptors on level walking include what two things?

A

time and distance parameters

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13
Q

Time parameters of walking on level ground

A 
stance time = 0.5 seconds
single support time
double support time
swing time
stride or step time
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14
Q

Double support

A

22% of gait cycle total
decreases when speed of walking increases
increases in elderly or those with balance issues
0 time spent in double support while running

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15
Q

stride vs step time

A

stride time is not very useful

step time is important! It will decrease on the affected side (limping)

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16
Q

Distance parameters of walking on level ground

A

stride length
step length
step width
degree of toe-out

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17
Q

Stride length

A

decreases in elderly

increases as speed of walking increases

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18
Q

step width

A

increases in those with balance issues

medial lateral direction

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19
Q

Rate (distance/time) variables

A

cadence: steps per min

walking/gait velocity: distance/unit of time

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20
Q

Cadence

A

comfortable speed = 80-110 steps/min
fast = 120 steps/min
40-55 strides/min = 80-110 steps/min
1 stride = 2 steps

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21
Q

Can two people walk at the same speed and have different cadences?

A

yes: kid walking with parents
kid has much higher cadence than parent
parent has larger stride length
cadence and stride length contribute to speed
pathologies cause decreased stride length

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22
Q

Walking/gait velocity

A

(0.9 - 1.7 m/s)
increases w/ increased cadence and stride length simultaneously
decreases w/ decreased angle of toe out and limb length or weight
increased speed = decreased duration of all stance phase components (sub phases)
avg walking gait/velocity = 1.3 m/s
walking at 1 m/s = slow

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23
Q

Other kinematic variables

A

center of mass position and velocity during gait
linear position, velocity and acceleration of the COM, pelvis, and head during gait
linear position and velocity of the toe during gait
angle change of each joint during gait

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24
Q

Displacement of COM in vertical and lateral directions

A

vertical displacement of COM = 5cm

lateral displacement of COM = 4cm

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25
Vertical displacement of COM
30% of gait cycle (end of midstance) is the highest point of trajectory 55% of gait cycle (middle of double support) is the lowest point of trajectory (preswing) at the same time of the highest trajectory = COM is closest to the foot that is in contact with the ground
26
Energy cost of gait
1. muscles affect the rate of energy expenditure during gait 2. the overall metabolic cost of walking can be assessed by measuring O2 consumption and CO2 production 3. Oxygen rate at average walking speed is 80 m/min or 1.3 m/s or 3 miles per hour. or 12 ml/kg/min (energy cost of walking)
27
how do muscles affect the rate of energy expenditure during gait?
``` increase/decrease speed of motion lift body against gravity decelerate different body segments stabilize joints so they don't move (co-contraction) lower BW ```
28
Compass vs normal gait
normal gait is more efficient than compass gait because vertical excursion is much smaller
29
Purpose of 6 determinants of gait
minimize COM movement, therefore minimizing energy consumption
30
6 determinants of gait
1. pelvic rotation about the vertical axis 2. pelvic tilt about AP axis 3. knee flexion in stance phase 4. ankle mechanism 5. foot mechanism 6. lateral displacement of body
31
Pelvic rotation
pelvic rotation decreases COM vertical displacement anteriorly at heelstrike and posteriorly at toe-off
32
Pelvic tilt
decreases COM vertical displacement
33
Knee flexion
decreases COM vertical displacement
34
foot/ankle mechanism
decreases COM vertical displacement during stance
35
Lateral displacement of body
normal leg = valgus, meaning knee joint centers closer than hip joint centers, allowing me to put feet closer together, meaning my COM does not displace/move as far in M/L direction during gait
36
Toe kinematics
max toe clearance is 1.3 cm (??) max horizontal velocity of foot during walking is 4.6 m/s (??) fast velocity of foot during swing with little toe clearance = high trip/fall risk lowest toe clearance occurs at max horizontal velocity of the foot!!!!
37
What happens to the head and pelvis M/L acceleration with age?
although acceleration in ml direciton of pelvis decreases slightly, the head motion increases and is more than the pelvis. head motion should be smaller than pelvic!
38
what happens to step width with age?
step width increases -- wider BOS -- safety mechanism -- more stability
39
Kinetic variables
``` (causes of motion) GRF center of pressure joint moment (torque) joint power ```
40
Foot kinematics at heel strike
vertical GRF = "M pattern/shape" of graph | spike in graph at IC = Heelstrike Transient
41
Heelstrike transient
abnormal spike in graph at IC coordination issue with IC of heel on ground, landing should be smooth. Knee is still in screwhome mechanism, so force from hitting ground will be transferred to knee
42
Forces that control walking
gravity (BW) air resistance internal muscles forces GRF
43
GRF
normal component = vertical forces shear component = AP and ML friction forces direction of GRF changes during gait
44
Vertical GRF
double peaks: 1st at heel strike (action of body momentum) 2nd peak at push off - contraction of calf muscle these peaks are higher than BW because you are creating more force IC = creating more force from ground. force is greater than BW to prevent COM from dropping
45
peak value of vertical GRF
120% BW at peaks (push off and heel strike)
46
When is the vertical GRF lower than your BW?
midstance - result of knee flexion
47
AP GRF component
magnitude and direction of AP shear force depends on position of COM relative to location of foot peak value = 20% BW sufficient friction force btwn foot and ground is needed to prevent slipping propulsive force of one limb is applied simultaneously to the braking force of the other limb when the weight is transferred from one limb to the other
48
AP GRF
magnitude and direction of AP shear force depends on position of COM relative to foot location: - in the posterior direction at heel strike for slowing the progression of the body - in the anterior direction at toe off for propelling body forward - larger the step length = greater shear forces
49
AP GRF during push off
during push off, tendency of motion is for foot to go backwards but friction applies force forwards (prevents slipping) 1st step = high positive on graph because you are gaining speed to slow down you have to create more negative force than positive
50
The magnitude of the ML shear force depends on the position of the COM relative to the foot:
lateral direction at heel strike medial direction during rest of stance phase larger step width = greater shear forces b/c of greater angle btwn LE and floor peak value = 5% BW wide variety depending on foot type peak value will increase if BOS increases medial force from ground helps transfer weight to opposite side during gait ML = friction force
51
Trajectory of COP during gait
at heel strike, COP is located lateral to midpoint of heel mid stance, COP moves more laterally from HO to TO, COP moves medially from MT heads to big toe pronated foot = COP shifted over medially
52
COP at LR
heel
53
COP at mid stance
heel and midfoot
54
COP at terminal stance
forefoot only
55
COP at pre swing
medial forefoot
56
Joint Moment at heel strike
at heel strike, the line of action of the GRF passes post to ankle joint, post to knee joint, and anterior to hip = ankle PF, knee flexion, hip flexion torques to prevent collapse of LE, these external torques are counterbalanced by internal joint moments that are created by ankle DF's, knee extensors, and hip extensors
57
Internal moments do not: (2 things)
1. do not indication the direction of motion 2. do not indicate co-contraction of agonists and antagonists a muscle being active doesn't mean the joint will move in that direction of contraction
58
Joint moment notes
at IC we have PF torque, but TA is active at knee = external flexion torque, but quads are active muscles create internal torques/moments to counter GRFs GRFs create external torques on joints
59
Torque + motion = ?
joint power
60
Definition of joint power
the rate of work performed by controlling muscles | the product of the net joint moment and the joint angular velocity
61
significance of joint power
indicating the net rate of generating or absorbing energy by all muscles and other connective tissues crossing the joint - positive value = power generation = concentric contraction - negative value = power absorption = eccentric motion and torque can be in the same or opposite directions
62
First rocker occurs when during the gait cycle?
IC thru LR
63
first rocker fulcrum
fulcrum = heel - DF moment | PF controlled by DF muscles to counter balance the PF torque of GRF
64
second rocker occurs when?
mid stance
65
fulcrum of second rocker?
fulcrum = ankle - PF moment DF controlled by PF muscles to counter balance DF torque of GRF rotation around ankle joint (fulcrum)
66
third rocker occurs when?
terminal stance
67
third rocker fulcrum
fulcrum = MT heads - PF moment PF produced by PF muscles heel rotates around MT heads occurs from RHO to LIC
68
Limitations of Kinematic data
kinematics can mislead w/ respect to determining how motion is coordinated by the muscles groups that created the motion (sprinter example)
69
Hip joint power peak at mid stance
extensor generation of power during mid stance
70
hip joint power peak at terminal stance
flexor absorption of power
71
hip joint power peak pre swing
flexor generation of power during pre swing
72
hip joint power peak loading response
abductor absorption of power during loading response
73
Knee joint power peak LR
extensor absorption of power during LR
74
knee joint power peak pre swing
extensor absorption of power during pre swing
75
Ankle power peak LR
DF absorption of power during LR
76
ankle power peak terminal stance
PF absorption of power during terminal stance
77
ankle power peak pre swing
PF generation of power during pre swing

Semester 2 FS Exam 10 (2 decks)

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