12. Lever Systems Flashcards
Fulcrum definition
Fixed point / pivot where lever rotates around
Effort definition
Point where force / effort is applied to
→ provided by muscle contraction
Load definition
Point where weight I resistance is coming from
→ physical object (dumbbell) or body weight
Functions of levers
- Increase speed & range of motion at which body can move
- generate maximal force against a given load / resistance
First class lever position
↓ effort |△ fulcrum |↓ load
First class lever examples
Joint at neck
Elbow extension
First class lever sporting examples
Header in football
Tripe extension
Second class lever position
↑ effort |↓load | △ fulcrum
Second class lever examples
Ankle / metatarsal joint
Second class lever sporting example
Calf raises
Long jump takeoff
Second class lever mechanical advantage
Very efficient at moving heavy loads with minimum effort
Second class Iever mechanical disadvantage
Can’t move heavy loads quickly / with full range of motion
Reason for second class lever mechanical advantage
Effort arm is longer than load arm
Third class lever positions
△ fulcrum | ↑effort | ↓load
Third class lever example
Elbow flexion
Hip/knee flexion/extension
Third class lever sporting example
Bicep curl
Leg extension (free kick)
Horizontal abduction (backhand shot)
Third class lever mechanical advantage
Greater range of motion
Larger speed generated / can move resistance quickly
Third class lever mechanical disadvantage
Requires more effort to lift equivalent load
Struggles to move heavy loads
Reason for third class lever mechanical advantage
Load arm is longer than effort arm
