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normal gait lecture Flashcards

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1
Q

when does peak DF occur in ankle joint during gait cycle?

A

50%

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2
Q

when does peak PF occur in ankle joint during gait cycle?

A

65-70%

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3
Q

when does peak knee flexion occur in gait cycle?

A

80%

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4
Q

when does knee extension occur in gait cycle?

A

45%

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5
Q

peak knee flexion during gait cycle in degrees

A

60

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6
Q

peak hip flexion during gait cycle in degrees

A

35

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7
Q

when does peak hip flexion occur in gait cycle?

A

90% (swing)

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8
Q

two categories of kinetics

A

external and internal forces

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9
Q

external forces

A

GRF, gravity, or push/pull from outside the body

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10
Q

internal forces

A

muscles, joint reaction forces, and ligaments or joint capsules

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11
Q

what law is GRF associated with?

A

Newton’s third law; every action has an equal and opposite reaction

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12
Q

what can measure GRF?

A

a force plate

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13
Q

what is a force plate?

A

a fancy bathroom scale that measures the magnitude and the direction of force

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14
Q

how does the magnitude of the GRF change throughout the gait cycle?

A

it increases throughout weight acceptance

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15
Q

newton’s second law

A

linear or angular acceleration is inversely proportional to the mass and directly proportional to the force

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16
Q

how does newton’s second law explain GRF?

A

as the ground exerts a force to the individual, the individual will accelerate in the direction of the force

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17
Q

GRF relationship to the joint axis of rotation

A

is the GRF does not pass through a centre of rotation, it will cause rotation

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18
Q

newton’s second law and third law and their relationship to heel strike

A

the initial GRF is applied opposite to the direction of movement, thus not accelerating the movement but acting as a break

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19
Q

what are the 3 planes that GRF can be measured in?

A

medio-lateral, anterior-posterior, and vertical

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20
Q

what plane is the largest component of the GRF?

A

vertical, this is because of the weight of the body

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21
Q

vertical GRF

A

is how much force is pushing back up from the ground

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22
Q

what is vertical GRF based on?

A

body mass and walking velocity

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23
Q

at what points in the gait cycle does GRF peak?

A

15% and 45%

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24
Q

at what point in the gait cycle does GRF decrease?

A

30% (besides before heel strike and after toe off)

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25
what is the maximum force during normal gait cycle relative to body mass in vertical axis?
about 1.2 - 1.4; gets up to about 2 during running
26
what is the second largest axis component of GRF?
anterior-posterior
27
anterior-posterior GRF
controls the forward velocity of the body
28
how does the anterior-posterior GRF change throughout the gait cycle?
is is negative during heel strike, then gradually increases and is positive during toe off
29
what is the maximum force during normal gait cycle relative to body mass in anteroposterior axis?
0.2 (much smaller than vertical force)
30
2 components of gait of the antero-posterior GRF
breaking (posterior GRF) and propulsion (anterior GRF)
31
what dictates changes in forward velocity?
the ratio of baking force to propulsive force
32
smallest component/axis of GRF?
medio-lateral
33
what is the mediolateral component of GRF important for?
balancing the body on the foot which is important for transferring weight from limb to limb in double support and allowing for change in direction
34
is the GRF lateral or medial during heel strike?
lateral
35
how does the GRF change in the mediolateral axis
heel strike is lateral and then the force changes to be medial; it is a small force
36
what is the maximum force during normal gait cycle relative to body mass in mediolateral axis?
0.07
37
centre of pressure
the average location of pressure and is the origin of the GRF
38
path of GRF throughout step
lateral calcaneus > anterior > medial
39
electromyography
measures the electrical activity associated with muscle activation
40
net moment
is the sum of all moments about an axis of rotation
41
what joint does PF/DF occur at?
tibiotalar joint
42
what joint does inversion/eversion occur at?
subtalar
43
primary muscles involved in ankle biomechanics during gait
gastroc, soleus, tib ant, and peroneals
44
major tasks of ankle during gait
maintain support of body throughout stance, foot clearance during swing, and to prepare foot for heel strike
45
if GRF is behind the COM in the foot, what movement will occur?
PF; this is due to gravity pulling the weight of the foot down, so it isn't only muscles creating movement
46
in the ankle joint, where does the moment peak?
around 50%, this is because the moment arm relative to the joint axis is greatest
47
when is the tib ant active during gait cycle?
0-10% and 60-100%
48
when are gastrocs active during gait cycle?
35-55%
49
why is tib ant active during first 10% of gait cycle
because it is acting as an antagonist muscle to slow down and control the movement
50
muscle activity during 10-30% of gait cycle
no activation and the GRF is acting as an external moment, causing the movement (DF), this is because the force is applied in front of the axis of rotation
51
ankle muscle activation 30-60% of gait cycle
the gastrocs are being stretched so they are activated as an agnoist in the first part, then are activated as a PF towards the end
52
muscle activation during 60-100% of gait cycle
tib ant is active and gastrocs are not, this is because they are directly causing DF
53
what is resultant angular acceleration proportional to?
the difference between the PF and DF moments
54
major tasks of knee during gait
shock absorption during loading, limb stability during single support, limb advancement and clearance during swing, and to prepare for initial contact/heel strike
55
major characteristics of knee during gait
flexed during loaded, extension in midstance, and large flexion in swing
56
when in the moment the largest in knee flexion?
about 15%
57
when is biceps femoris active during gait cycle?
slightly during heel strike and mostly throughout swing
58
when is rectus femoris active during gait cycle?
during first 10-30% of cycle; this is during flexion of the knee but the muscle is acting as an agonist, thus controlling the movement
59
major tasks of hip during gait
to stabilize pelvis and to initiate limb advancement
60
muscle activity of hip extensors during gait cycle
during first 10% and from 85-100%
61
hip flexor activity throughout the gait cycle
is mainly active during 70-100%
62
when does the moment peak for hip flexion during gait cycle?
about 50%
63
hip during 15% of gait cyle
the GRF is in front of the hip joint axis, but flexion is not the intended movement; concentric muscle action needed by hip extensors to promote intended movement
64
measuring internal vs external forces
internal forces are estimated but external forces can be directly measured
517
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