Biomechanics - stability and lever systems Flashcards
Define centre of mass and give a sporting example which uses this
The point at which a body is balanced in all directions.
High jump (Fosbury flop technique) - J curve creates greater velocity in the approach. Planting outside foot, lifting inside foot and arms up to raise centre of mass. The athlete then extends their spine to rate around the bar to move centre of mass outside.
Define stability
Ability of a body to resist motion and remain at rest, remaining in a balanced position.
What are the 4 factors that affect stability
mass
height
base of support
line of gravity
How do you maximise stability using a sporting example
A sprinter will crouch down onto the blocks, lowering centre of mass. The base of support will be large and line of gravity falls, causing high mass due to their high proportion of muscle mass.
How do you maximise stability using a sporting example
When ‘set’ is called the sprinter lifts their hips, raising centre of mass. Lifts knee reducing contact, leans forward shifting the line of gravity. Reducing stability.
When the gun is fired, chest lifts rising centre of mass and hands move off the track minimising base of support.
Define lever system
Are the coordination of our bones and muscles to create movement.
Its main functions is to generate muscular effort to overcome a given load and increase speed of a given movement.
What are the components parts of a lever system
Lever (bone)
fulcrum (joint)
Effort (force)
Load (weight or resistance)
What is the first class lever system
________________
| | |
E F L
example - extension of the neck when preparing to head a football
What is the second class lever system
E
^
________________|
| |
F L
example - ball of the foot in the take off phase of a highjump (ELF backwards)
What is the third lever system
E
^
______|__________
| |
F L
example - flexion of the elbow during a bicep curl
What is the effort arm
The distance from the fulcrum to the effort
What is the load arm
The distance from the load to the fulcrum
Define mechanical advantage
Effort arm is greater than the load arm, a large load can be moved with small effort - 2nd class lever system
Define mechanical disadvantage
Load arm is greater than the effort arm. Large effort is required to move a small load - 3rd class lever system.
