3.2 - Biomechanical principles: Stability and Lever systems Flashcards
centre of mass definition
point at which a body is balanced in all directions; point from which weight appears to act
depends on position of body, if in anatomical position, its at naval area
stability definition + factors that affect
ability of a body to resist motion and remain at rest
- mass of the body
- height of centre of mass
- base of support
- line of gravity
how to maximise stability
- low centre of mass
- large base of support
- high mass
how to minimise stability
high centre of mass - raise chest
reduce points of contact (lift knee + hand)
lean forward to shift line of gravity
2 main functions of lever systems
generate muscular effort to overcome a load
+ increase speed of given movement
123
FRE
first class lever
EFR, both point down
eg, extension of neck preparing to head football
second class lever
FRE, R DOWN, E UP
- mechanical advantage
eg, ball of foot in take off phase of high jump
third class lever
REF, E UP, R DOWN
- mechanical disadvantage
eg, flexion of elbow during a bicep curl
greater distance of effort/load =
more significant as longer levers generate greater forces = give acceleration to projectiles
mechanical advantage definition
second class lever systems where effort arm is greater than load arm = higher force
mechanical disadvantage definition
third class leer systems where load arm is greater than effort arms = lower force
Fosbury flop technique
- uses a j curve to allow a greater approach
- plants outside foot to allow inside leg lift, along with the arms at takeoff to raise the centre of mass as high as possible
- fully extends spine to rotate around the bar moving centre of mass outside the body and under the bar.
