Topic 7 Exam 2

Question 1

What does a stabilogram access?
1. How can we assess posture using a stabilogram?

Answer 1

How much postural sway there is

How much does the center of mass change when you close your eyes

Question 2

2. How do young adults and elderly differ in postural sway?

Answer 2

Elderly have more postural sway especially in the medio-lateral direction

Question 3

3. What are predictive strategies during upright standing?

Answer 3

Predictive
* Calf muscles
* Forward = shorten
* Back = lengthen
* *not a stretch response

Question 4

3. What are reactive strategies during upright standing?

Answer 4

When outside disturbance exceeds the predictive strategy’s ability to maintain
equilibrium = Reactive
* Reflex contributes to automatic postural
response strategy

Question 5

3. Predictive and reactive strategies during upright standing

What is their role in maintaining balance and posture? Be able to describe examples for each.

Answer 5

Control of equilibrium for postural sway

Question 6

4. Name and describe the five automatic postural reactions.

Answer 6

Hip strategy
Ankle strategy
Stepping Strategy
Weight Shift Strategy
Suspension Strategy

Question 7

Automatic postural reactions

Hip strategy

Answer 7

Proximal to distal activation of muscles – same side as COG shift

• Perturbations that are large in comparison with the supporting surface
  = task requires a large or rapid shift in COG
• *Appears only if vestibular reception is intact

Question 8

Automatic postural reactions

Ankle strategy

Answer 8

Older adults wont use this, instead you will see them use the hip stragety

Distal to proximal activation of muscles –

opposite side as COG shift (“elongation of the weight-bearing side“)
* Small shifts or perturbations of COG = task requires maintenance of upright posture

• *Appears only if somatosensory reception is intact

Question 9

Automatic postural reactions

Stepping Strategy

Answer 9

When limits of stability are reached or exceeded, muscles activate to
allow a compensatory weight shift
* Large, gross perturbations

Question 10

Automatic postural reactions

Weight Shift Strategy

Answer 10

Shifting from one leg or limb to the other

Question 11

Automatic postural reactions

Suspension Strategy

Answer 11

Lower COG by quickly flexing knees

• During accelerations and momentum with perturbations (i.e. roller
  skating)

Question 12

5. What did the study by Mackey & Robinovitch (2005) determine about postural stability and fall risk?

Answer 12

Postural steadiness measures NOT correlated with balance recovery measures

Question 13

6. Can adjustments be made to automatic responses i.e. can they change with experience/through learning? Describe the example from class.

Answer 13

Yes they can change

In 4 trials there was then adjustment

Question 14

7. What was the moving room experiment?

What did it reveal about the influence of the visual sense on balance? What specific aspect of visual perception was involved?

Answer 14

The floor is stationary it is not moving, the walls and ceiling are moving messes up optic flow (by generating optic flow)

What did it reveal about the influence of the visual sense on balance? INFLUENCES IT

What specific aspect of visual perception was involved? OPTIC FLOW

INFANT:
As the wall moved closer to their face they fell on their butt

As the wall moved farther forward they stumbled forward

ADULT:
As the adult is standing on a balance beam, the walls move and the adult becomes unstable

Question 15

automatic response…….

Answer 15

can be modified, reflexes can not be modified

Question 16

Moving room generated movement of…….

Answer 16

Optic flow