levers

a lever is a rigid rod(bone) that turns round a pivot(joint)

the fulcrum is the point around which the lever rotates

the load is the force applied by the lever system

the effort is the force that is applied by the user of the lever system

in the body the fulcrum is the joint, the load is the thing you want to move and the effort is supplied by the muscles

classes of levers:

first class levers:

the fulcrum sits in the middle 

an example of a first class lever could be an oar on a boat. effort is applied by pulling one end of the oar and this applies force on the water-the load.

in the body first class levers are used in exercises where the elbow or knee is straightened for example the elbow in triceps extensions and dips.

the elbow is the fulcrum which lies between the load-the weight held in the hand- and the effort applied by the triceps muscle at the back of the arm.

second class levers:

the load lies between the fulcrum and the effort.

an example of a second class lever could be a wheelbarrow. the fulcrum is the wheel the handles take the effort and the load is whatever is between them.

in the body second class levers are used in exercises like calf raises. the body weight-load-sits between the toes and balls of the feet-fulcrum-and the calf muscles apply the effort by pulling on the heel.

third class levers:

the effort is applied between…