GRF Flashcards

1
Q

Vertical GRF

A

perpendicular to supporting surface
most commonly analyzed in biomechanics

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2
Q

A/P GRF

A

parallel to supporting surface in the direction of movement

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3
Q

M/L GRF

A

parallel to supporting surface and perpendicular to direction of movement

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4
Q

First peak of vertical GRF

A

occurs during loading response
deceleration of downward movement of body
called impact peak

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5
Q

Second peak of GRF

A

occurs during terminal stance
propulsion/push-off from plantar flexors

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6
Q

Dips of GRF

A

-occurs during midstance
-dip happens because we accelerate upwards, unloading from ground
-coincides with peak of vertical displacement

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7
Q

A/P GRFs description

A

-braking force through first half of stance phasev(dips)
-propulsive force during second half of stance phase (peaks)
-average about 20% of bodyweight

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8
Q

M/L GRFs description

A

-avg about 5% of bodyweight
-medially directed through most of stance phase

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9
Q

How can we tell how much force or torque is acting on each joint?

A

embedded force sensor
inverse dynamics

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10
Q

Inverse Dynamics

A

Kinematics
GRF
Anthropometrics

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

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11
Q

Inverse Dynamics Output

A

at each lower extremity jt there is a net internal joint force & net internal joint moment

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12
Q

Internal forces and moments (of inverse dynamics)

A

muscle contraction
passive soft tissue stretch/tension
bony contact forces

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13
Q

External Moments

A

-represents the torque applied to the joint by external forces
-internal torque is counteracts it
-knee OA is an example

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14
Q

What joint does GRF directly act on?

A

foot/ankle

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15
Q

Backward Trunk Lean

A

-causes the GRF vector to shift posteriorly in comparison to hip joint
-shifts external hip moment from flexion to extension, aiding in hip extension
-decreases internal moment hip extensors have to produce

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16
Q

Forward Trunk Lean

A

-likely shifts the GRF force vector anteriorly
-shifts external knee moment from flexion to extension, aids in knee extension
-reduces internal moment the knee extensors have to produce

17
Q

This component of the ground reaction force provides information about “braking” and “propulsive” forces during walking

A

Anterior/Posterior

18
Q

This component of the ground reaction force generally has two peaks - an impact peak and a propulsive peak

19
Q

This is the method researchers use to estimate joint forces and moments at the ankle, knee, and hip during locomotion

A

Inverse Dynamics

20
Q

What is not a contributor to internal forces and moments?

A

Ground reaction force

21
Q

Why is it important to consider joint moments as a physical therapist?

A

Joint moments can be an indicator or predictor of joint pathology

22
Q

What muscle is not generally active during the loading response of “normal” walking gait?

23
Q

This muscle is active during the loading response and helps initiate hip extension during the walking gait cycle.

A

Gluteus maximus

24
Q

This muscle helps eccentrically control knee flexion during initial contact and the loading response of the gait cycle.

A

Vastus lateralis

25
This subcomponent of gait refers to one's ability to dynamically control their trunk and COM in the frontal plane during gait.
Postural stability
26
This movement construct can be observed by comparing movement of the right and left limbs during gait.
Symmetry