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Kin 147 > Week 8 > Flashcards

Week 8 Flashcards

1
Q

What is the normal range for impact peak in GRF during running

A

1.5 - 2 BWs

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2
Q

What is the normal range for active peak in GRF during running

A

2 - 3 BWs

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3
Q

What is the normal range for loading rate in GRF during running

A

50 - 100 BWs/sec

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4
Q

What is a moment

A

Moment or moment of force are a synonym for torque

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5
Q

What is torque

A

The ability of a force to cause rotation about an axis

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6
Q

What is a joint moment

A

ability of a force either internal or external to cause rotation about a joint

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7
Q

Equation of torque is

A

Moment arm x Force

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8
Q

How can we tell how much force or torque is acting on each joint (how can we measure it)

A

Embed Force Sensor - direct

Inverse dynamics - indirect

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9
Q

Embed force sensor is usually used on

A

Amputee population

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10
Q

Inverse dynamics is

A

An indirect estimation of force and torque acting on a joint based on several measurements

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11
Q

What do we need to collect from inverse dynamics

A

Kinematics of each segments

Ground reaction forces

Anthropometrics of each segment

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12
Q

Receiving Kinematics of each segments involves finding the (Inverse dynamics)

A

Position
Velocity
Acceleration

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13
Q

Receiving Ground reaction forces involves finding the (Inverse dynamics)

A

Anterior/posterior
Medial/lateral
Vertical

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14
Q

Receiving Anthropometrics of each segment involves finding the (Inverse dynamics)

A

Length
Mass
Center of mass location
Moment of inertia

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15
Q

How would you get mass / COM location for each segment

A

Use table of values based on cadaveric studies from research study

Then:

  1. Look at definition of body segment
  2. Segment weight compared to body weight as %
  3. Look at center of gravity from proximal end
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16
Q

What is mass

A

A quantity expressing a bodys tendency to resist LINEAR acceleration

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17
Q

What is moment of inertia

A

A quantity expressing a bodys tendency to resist ANGULAR acceleration

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18
Q

Force =

A

Mass x Acceleration

19
Q

Torque =

A

Moment of Inertia x Acceleration

Or

Force x moment arm

20
Q

As you go up the leg

A

There are more estimates involved

This is because you use one estimate for the next estimate

21
Q

What are the steps for inverse dynamics

A
  1. Use GRF and foot information (Kinematics and anthropometrics) to estimate the internal ankle forces and moments
  2. Internal ankle forces and moments then used with SHANK information to estimate internal knee forces and moments
  3. Internal knee forces and moments then used with THIGH information to estimate internal hip forces and moments
22
Q

What do you end up with in inverse dynmaics

A

At each lower extremity joint (ankle, knee and hip):

Net internal joint force
Net internal joint moment

23
Q

What units for torque

A

N*m

Normalised to N*m/kg

24
Q

Internal forces and moments are mainly caused by

A

Muscle contractions

Passive soft tissue stretch/tension

Articular reaction forces

25
Q

Net internal force + net external force =

A

Mass * acceleration

26
Q

Net internal moment + net external moment =

A

Moment of inerta * acceleration

27
Q

External forces are

A

GRF

28
Q

So when we do inverse dynamics we collect

A

Internal forces and moments

29
Q

What is often reported in literature

A

External moment since this is what represents the torque applied to the joint by external forces

30
Q

What counteracts external torque created by the GRF

Why

A

Internal torque

The muscles react and contract to create an internal torque to counteract the external torque

Reduces the external load on the joints - injury

31
Q

The counteracting nature largely related to

What also is a factor

A

The interaction between the GRF and the joint

e.g. direction of GRF and what it causes to happen at the joint

Other joint forces and moments will also play a factor

e.g. the forces and moments at the ankle could play a factor in the force and moments of the knee

32
Q

Muscles and other soft tissue structures will…

A

Counteract the external moment to produce the internal moment

33
Q

High external knee varus moments have been linked to

A

Increased pain and rate of disease progression in patients with knee osteoarthritis

34
Q

Torque, moment, and moment of force are all synonyms and mean the same thing

A

True

35
Q

Inverse dynamics is a method of directly measuring the amount of force and torque is applied to a joint

A

False

36
Q

Which of the following pieces of information is NOT needed to perform inverse dynamics

A

Walking/Running velocity of the participant

37
Q

How do we estimate segment weight and center of mass location

A

This information is estimated by using guidelines published from cadaveric studies

38
Q

When performing inverse dynamics, which joint force and moment are estimated first

A

Ankle

39
Q

Joint moments are normalized by body mass for what reason

A

So that we can compare data across participants

40
Q

During inverse dynamics we are actually solving for what

A

The internal joint forces and moments

41
Q

The external joint moment represents the torque applied to the joint by other external forces

A

True

42
Q

The vertical ground reaction force is generally the only force we can directly measure with inverse dynamics

A

False

43
Q

Higher joint moments for what joint and plane have been strongly associated with a higher rate of disease progression in knee osteoarthritis

A

Knee varus

Kin 147 (12 decks)

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