The human body is built around a sturdy frame called the skeleton. Muscles are attached to the skeleton and generate movement. Many levers exist within the skeletal structure.

Nature has designed the human body for movement rather than maximising force.

The forearm is a classic example of nature's way of maximising motion rather than force. The biceps is a muscle that flexes the arm. Tendons attach this muscle close to the elbow.

Now, the forearm is an example of a third order lever.

Identify the fulcrum, load and effort.
The effort is where the muscle is attached. You can flex your biceps and find where they attach on your forearm.

What type of lever is the forearm?
Is it designed to maximise distance or force?.

In nature why is it more important to multiply the distance rather than the force?.

Redesign this lever to be a force multiplier.

The thigh muscles (quadraceps) are attached to the shin bone (tibia) just below the knee joint. Look at the athlete on the right as he performs the leg extension exercise.

Identify the fulcrum, load and effort of this particular lever system.

What type of lever is this?

The muscle generates movement by shortening and pulling on a bone. Compare the amount the muscle shortens with the amount of movement generated in the lower leg.
Is this lever system designed for force or speed mulitplication?

The kicking action is animated on the right.

What muscles are involved to start the femur moving? Where are these muscles attached?

Identify all the levers involved.

What type of lever is each?