Stability and Balance

Question 1

Define balance

Answer 1

The ability to control equilibrium (state of zero acceleration)

Question 2

How is balance maintained?

Answer 2

Centre of gravity is over the base of support

Question 3

Define stability

Answer 3

The tendency of a body to remain in or return to its initial position following the application of a force

Question 4

What is dynamic stability?

Answer 4

The ability to react to a stimulus to correct balance

Question 5

What is passive stability?

Answer 5

The stability that a person has- does not need to be corrected

Question 6

What factors affect passive stability?

Answer 6

1. Weight - higher weight = more stable
2. Area of the base - larger area = more stable
3. Horizontal distance from CoG to pivot point - bigger distance = more stable
4. Height of CoG above the base - short = more stable

Question 7

What is the pivot point?

Answer 7

The point at which the object will move if pushed

Question 8

What are the 3 types of equilibrium?

Answer 8

Stable, unstable, neutral

Question 9

What is stable equilibrium?

Answer 9

Potential energy at a minimum
Work must be done to change
Tendency to return to original posture

Question 10

What is unstable equilibrium?

Answer 10

Potential energy at or near a maximum
Very little if any work must be done to change
Small movement takes the gravity line outside the base

Question 11

What is neutral equilibrium?

Answer 11

The object moves but no change in potential energy
Base of support small but doesn’t matter

Question 12

How are humans dynamically stable systems?

Answer 12

CoG must remain within base of support or extra forces need to push on it to get it back within a stable position
Requires muscular forces to remain balanced
Puts the body into a state of active/ dynamic equilibrium

Question 13

How can we modify factors to increase stability?

Answer 13

• Keeping CoG over base of support
• Lowering CoG
• Increasing mass
• Extend base of support towards oncoming force
• shift CoG towards oncoming force

Question 14

Define human balance

Answer 14

The active control of the physical shape of the limbs to provide varying degrees of passive stability, and muscular actions to provide compensating active stability for passive insufficiencies

Question 15

What are the common reflex balance mechanisms and what order do they occur in?

Answer 15

1. Ankle strategy - plantar flexing
2. Hip strategy - flexing at the hips
3. Stepping response
4. Arm circles - creates momentum in the opposite direction