Movement analysis — Edexcel GCSE Physical Education revision

Lever systems

• A lever system has a fulcrum (pivot), effort (force applied by muscle) and load (resistance being moved).
• First class levers have the fulcrum between the effort and the load, e.g. the neck nodding the head (atlanto-occipital joint).
• Second class levers have the load between the fulcrum and the effort, e.g. standing calf raise (ball of foot as fulcrum, load at ankle, effort from calf muscle).
• Third class levers have the effort between the fulcrum and the load and are the most common in the human body, e.g. the elbow during a bicep curl.
• Mechanical advantage occurs when the effort arm is longer than the load arm, allowing a smaller force to move a larger load (more common in second class levers); third class levers favour speed of movement over force.

Planes and axes of movement

• The sagittal plane divides the body into left and right sides; movement in this plane occurs around the transverse axis, e.g. flexion and extension such as running or a somersault.
• The frontal plane divides the body into front and back; movement in this plane occurs around the sagittal axis, e.g. abduction/adduction such as a cartwheel or star jump.
• The transverse plane divides the body into upper and lower halves; movement in this plane occurs around the longitudinal axis, e.g. rotation such as a discus throw or twist.
• Matching planes to axes is a common exam focus: sagittal plane ↔ transverse axis; frontal plane ↔ sagittal axis; transverse plane ↔ longitudinal axis.

Key terms

Fulcrum

The fixed pivot point of a lever system, usually the joint.

Effort

The force applied by a muscle to move a load in a lever system.

Load

The resistance being moved by a lever system, e.g. body weight or an object.

First class lever

Lever with the fulcrum between the effort and the load.

Second class lever

Lever with the load between the fulcrum and the effort.

Third class lever

Lever with the effort between the fulcrum and the load; most common in the body.

Common exam traps

• Mixing up which class of lever has which arrangement — remember: 1st = fulcrum in middle, 2nd = load in middle, 3rd = effort in middle.
• Forgetting that third class levers are the most common in the human body, even though they favour speed rather than force.
• Confusing the sagittal plane (left/right split) with the frontal plane (front/back split).

Practice questions with answers

1. 1. What are the three components of a lever system?

   • • Fulcrum, effort, load
   • • Bone, muscle, joint
   • • Agonist, antagonist, fixator
   • • Flexion, extension, rotation

   Answer: Fulcrum, effort, load

   Every lever system has a fulcrum (pivot), effort (force) and load (resistance).

2. 2. In a first class lever, where is the fulcrum positioned?

   • • Between effort and load
   • • At one end only
   • • Beyond the load
   • • There is no fulcrum

   Answer: Between effort and load

   First class levers have the fulcrum located between the effort and the load.

3. 3. Give an example of a first class lever in the human body.

   Answer: The neck nodding the head (atlanto-occipital joint)

   The head nodding at the top of the spine is a classic first class lever example.

4. 4. Which lever class has the load positioned between the fulcrum and the effort?

   • • First class
   • • Second class
   • • Third class
   • • Fourth class

   Answer: Second class

   In a second class lever the load sits between the fulcrum and the effort, e.g. a calf raise.

5. 5. Which lever class is most common in the human body?

   • • First class
   • • Second class
   • • Third class
   • • They are all equally common

   Answer: Third class

   Most joints in the body, such as the elbow, operate as third class levers.

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