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
• Effort

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

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

  • This is the weight of the body parts that move when muscles contract
• 1st Class Lever (EFL)

  The fulcrum is in the centre of the lever in between the effort and the load

  • E.g. extension of the lower arm (load) using the tricep muscle (effort) around the elbow joint (fulcrum)
• 2nd Class Lever (ELF)

  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
• 3rd Class Lever (FEL)

  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)