Lever Systems in Sport (AQA GCSE Physical Education (PE))

First, Second & Third Class Lever Systems

• The presence of pivot points at the joints in the body means that skeletons act as levers, transferring the size and direction of force

• Levers have three key components:

  • A point of effort, also known as force

    • In the body, this effort is carried out by muscles when they contract

  • A point of load, also known as resistance

    • This is the weight of the body parts that move when muscles contract

  • A pivot point called the fulcrum

    • This is the joints of the skeleton

• There are three different types of lever:

  • First class levers: the fulcrum is in the centre of the lever in between the effort and the resistance

    • E.g. extension of the lower arm (load) using the tricep muscle (effort) around the elbow joint (fulcrum)

  • Second class levers: the load is in the centre of the lever in between the fulcrum and the effort

    • E.g. plantar flexion which involves contraction of the gastrocnemius muscle in the lower leg (effort) with the ball of the foot as the fulcrum and the weight of the person as the load

  • Third class levers: the effort is in the centre in between the resistance and the fulcrum

    • E.g. flexion of the lower arm (load) using the bicep muscle where it attaches to the lower arm below the elbow (effort) around the elbow joint (fulcrum)

Classes of lever diagram

Muscles attach to bones at the joints, creating a system of levers