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SPEX 201 > Lecture 16 + 17 - Intro into Kinetics : Gait Analysis > Flashcards

Lecture 16 + 17 - Intro into Kinetics : Gait Analysis Flashcards

1
Q

what are the three laws of the study of forces that cause motion

A
  • a push or pull : disturbing objects from their initial states (first law)
  • a net force accelerates and object (second law)
  • any force exerted is opposed by an equal and opposite force (third law)
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2
Q

1 N of force will accelerate a 1kg object by

A

1 m/s every second

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3
Q

force is a

A

vector quantity

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4
Q

what is GRF

A

ground reaction force

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5
Q

what is COP

A

centre of pressure

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6
Q

centre of pressure can be misleading, why

A

can be misleading as it is not a measure of pressure but a measure of position and refers to the average pressure point beneath the foot or feet

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7
Q

what are the objectives of gait

A

propel our bodies forward

to do so efficiently, requiring minimal energy expenditure

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8
Q

vertical ground reaction forces are a direct response to

A

centre of mass and its movement over base of support

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9
Q

what are horizontal ground reaction forces during gait

A

breaking and propulsion forces

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10
Q

what are the mediolateral ground reaction forces during gait

A

pronation and supernation of your foot

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11
Q

forces are sometimes normalised to body weight why

A

can be a way of comparing people with different body weights

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12
Q

the first peak of vertical forces during normal walking (heel strike to first peak F1) should be

A

1.2 times the persons body weight

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13
Q

what are the first bumps in initial contact (heel strike to first peak)

A
  • first little bump may be first contact of heel
  • then first peak should be 1.2 times body weight and is foot flat
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14
Q

what is happening during first peak F1 to trough F2 during vertical forces when normal walking

A

from flat food to mid stance

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15
Q

what happens to force during first peak F1 to trough F2

A

force is less than body mass

force is 0.6 times the persons body weight at trough

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16
Q

what happens to force during trough F2 to second peak (F3)

A

force should be almost equivalent to the first peak

F3 should be 1.2 times the persons body mass

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17
Q

what is happening during second peak F3 to toe off

A

gone from peak foot down to moving into the next step

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18
Q

what is happening to the foot during second peak to toe off

A

the foot is unloaded as the load is transferred to the opposite foot

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19
Q

during the second peak to toe off the time taken to off load the foot will related to

A

the speed of transfer of the weight to the front foot

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20
Q

during the second peak to toe off, the longer the offloading period from ..

A

from the back foot, the lower the first peak during loading on the front foot

21
Q

what is the time of initial contact for the first peak like for an amputee gait

A

slower to accept weight in the amputee gait, slow to step onto it and quick to get off it

  • see that it takes a little longer to get that heel strike foot flat, first peak
  • more mediolateral shift than up and down
22
Q

what are ground reaction forces

A

ground reaction force is the measured action - reaction force of our push against the ground

23
Q

the shape of the vertical force component curve shows

A

confidence to load stance foot

height change of the centre of mass

indicates speed of movement

24
Q

what are the vertical components of ground reaction forces during walking

A
  1. heel strike to first peak (F1)
  2. first peak (F1) to trough (F2)
  3. Trough (F2) to second peak (F3)
  4. second peak (F3) to toe off
25
Q

what are the anterior posterior components of ground reaction forces during walking

A
  1. heel strike to posterior peak (F4)
  2. prosterior peak (F4) to crossover
  3. crossover to anterior peak (F5)
  4. anterior peak (F5) to toe off
26
Q

what is happening during heel strike to posterior peak

A

after the initial claw back (if present), the heel is in contact with the ground and the body decelerates causing a prosterior shear force

27
Q

prosterior peak (breaking force) should be

A

0.2 times the persons body weight

28
Q

what is the middle of trough like for amputee gait

A

middle of the trough is similar space, they move to swing phase at same pace, using mediolaterial sway

29
Q

what is time to last peak of vertical forces like for amputee gait

A

time of the last peak is very similar to the healthy

30
Q

what can cause the claw back during heel strike to prosterior peak to be bigger or smaller

A

the surface we are walking on

31
Q

why are breaking forces negative

A

because it is the resistant forces pushing back towards us when in contact with the ground

32
Q

what is claw back

A

our initial heel strike and we pull back, reactive force thats moving just initially because we are adjusting to the surface

33
Q

what situations may there be more claw back

A

walking on ice

34
Q

what is happening in prosterior peak to cross over

A

the body begins to move over the stance limb, reducing the horizontal component of the resultant ground reaction force

35
Q

at the crossover point the horizontal force

A

is 0, therefore the only force acting is that of the vertical ground reaction force

36
Q

crossover should occur around

A

55% of stance phase

37
Q

what is happening in crossover to anterior peak

A

swing limb is in front of us and we are lifting our heel to move forward

  • the heel lifts and the foot is pushed down and back into the ground
  • this has the effect of producing an anterior component of the ground reaction force, which propels the body forwards
38
Q

the propulsion force of anterior peak should be

A

0.2 times the persons body weight

39
Q

what is happening during anterior peak to toe off (and what happens to the anterior force)

A

the period of terminal double support, where force is now being transferred to the front foot and the anterior force, therefore reduces

40
Q

during anterior peal to toe off the length of time the force takes to reduce and offload can

A

affect the loading during next foot contact

41
Q

when looking at anteriror and prosterior ground reaction forces what would be seen if the person was speeding up

A

the second peak would be larger as need to have more propulsion compared to breaking in order to be accelerating

42
Q

when looking at anteriror and prosterior ground reaction forces what would be seen if the person was trying to stop

A

much larger breaking force than propulsion force

43
Q

what are the phases of mediolateral force during gait

A

start on the outside

as you start to plant your foot you role inwards and go into pronation

go through neutal

then propel off your great toe so go back pronation

44
Q

what is the medialateral ground reaction force in early stance

A

greater lateral ground reaction force

45
Q

what is the medialateral ground reaction force in late stance

A

greater medial ground reaction force

46
Q

Pedotti digrams rely on the information provided by

A

force plates

47
Q

the interaction of what can be shown on a pedotti diagram

A

vertical and anterior - prosterior force can be shown on pedotti diagram

48
Q

to construct of pedotti diagram what is needed

A

need to know the vertical and horizontal forces and the position of the centre of pressure in the plane of interest for each moment in time

SPEX 201 (29 decks)

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