Biomechanics - stability and balance Flashcards
What is centre of mass?
the conceptual point where all the mass of a body can be considered to be concentrated
Is centre of mass tangible or not tangible?
not tangible
Can we assume that centre of mass and centre of gravity are relatively the same?
yes
List the features of centre of mass
- distribution of mass is equal in all directions
- does not depend on gravitational field
List the features of centre of gravity
- distribution of weight is equal in all directions
- does depend on gravitational field
- stronger gravity acting on your feet than head
Define balance
the ability to control equilibrium (state of 0 acceleration)
- is achieved and maintained through stability
When it comes to balance and centre of gravity where is the centre of gravity located?
over the base of support
Define stability
the tendency of a body to remain in or return to its initial position following the application of a force
What are the 2 types of stability?
- passive
- dynamic
What is the positive of stability?
the more an athlete can control and manipulate stability, the more likely they are able to execute skill/technique
What does passive stability depend on?
- weight (more stable)
- area of the base (more stable)
- horizontal distance from the centre of gravity to pivot point (more stable)
- height of the centre of gravity above the base (less stable)
What are the 3 types of equilibrium?
- stable
- unstable
- neutral
List the features of stable equilibrium
- potential energy at a minimum
- work must be done to change
- tendency to return to original posture
List the features of unstable equilibrium
- 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
List the features of neutral equilibrium
- object moves but no change in potential energy
- base of support small, doesn’t matter
What stability systems do humans have?
dynamically stable systems
What are the features of dynamically stable systems?
- centre of gravity must remain within base of support or extra forces need to push on it to get it back within a stable position
- require muscular forces to remain balanced
- puts the body into a state of active/dynamic equilibrium
What is motor control?
- the study of how movement is controlled
- the ability to regulate or direct the mechanisms essential to movement
- regulation or maintenance of a function or action
List the modifiable factors to increase stability
- keeping centre of gravity over base of support
- lowering centre of gravity
- increasing mass
- extend base of support towards oncoming force
- shift centre of gravity towards oncoming force
Define human balance
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
What are the common reflex balance mechanisms (increasing response to severity of perturbation and safety constraints)
1) ankle strategy
2) hip strategy
3) stepping response
4) arm circle
