Movements 2. Levers

Question 1

Lever definition

Answer 1

A lever is a rigid bar (body segment) which rotates around of fulcrum (joint axis) the rotation is produced by an effort force (contracting muscle) applied to lever

The effort has to overcome the resistance force to produce movement for example gravity weight or external resistance

There are 1st class leavers 2nd class leavers and 3rd class

Question 2

1st class leaver

Answer 2

E⬇️. R⬇️
————————
🔼F

Elbow in throwing a javelin

Trendelenburg effect in hip: Weakness on right hand side of hip results in hip tilting to the left

E= adductor muscles
F= hip
R=weight on pelvis

Question 3

2nd class lever

Answer 3

⬇️R. ⬆️E
————————-
🔼F

Most efficient= mechanical advantage

Wheel barrow

Standing calf raise

F=hip
R= body weight
E= calf

Question 4

3rd class lever

Answer 4

E⬆️. R⬇️
————————-
🔼F

Bicep curl

F= shoulder
E= bicep
R=weight

MA less than 1 however movement is quicker

Question 5

Mechanical advantage

Answer 5

Efficiency depends on where forces are located in relation to the Falcon

Leavers can be used so that small force can move a bigger force

Make exercise easier or longer for patience

E.g. Making a lever smaller holding a tennis racket in abduction is harder than holding a tennis racket in abduction with elbow flexed Effort arm is longer than resistance arm

E
— = + 1 = mechanical advantage
F