Lever Systems in Sporting Actions

Now that you understand the three classes of lever, you need to be able to apply this knowledge to real sporting actions. AQA GCSE PE (spec 3.1.2) requires you to identify the lever class, fulcrum, load and effort for movements at the elbow, knee and ankle. This lesson works through the key sporting examples you need to know and provides a structured approach to analysing any lever system in sport.

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The Three Key Joints

For AQA GCSE PE, you need to focus on lever systems at three joints:

Joint	Lever Class (main action)	Key Sporting Actions
Elbow	Third class (flexion and extension)	Bicep curl, push-up, throw-in, shot in basketball
Knee	Third class (extension)	Kicking a ball, squats, jumping
Ankle	Second class (plantarflexion)	Running (push-off), jumping (take-off), calf raise

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Lever System at the Elbow

Flexion at the Elbow (Bicep Curl)

When you flex (bend) your elbow — for example, during a bicep curl or a football throw-in — you are using a third class lever.

Component	What It Is
Fulcrum (F)	Elbow joint
Effort (E)	Biceps brachii muscle (inserts on the radius, close to the elbow joint)
Load (L)	Weight of the forearm + whatever is being held (ball, dumbbell, etc.)

Order: F — E — L (Third class)

graph LR
    F["F<br>Elbow joint"] --- E["E<br>Biceps"] --- L["L<br>Weight in hand"]
    style F fill:#e74c3c,color:#fff
    style E fill:#27ae60,color:#fff
    style L fill:#4a90d9,color:#fff

Sporting examples of elbow flexion:

Sport	Action	Description
Football	Throw-in	The player flexes at the elbow to bring the ball behind the head, then extends to release
Basketball	Shooting / passing	Elbow flexion and extension control the ball release
Weightlifting	Bicep curl	The classic example of elbow flexion against resistance
Cricket	Catching	The hands move towards the body as the elbow flexes to absorb the ball
Boxing	Uppercut	Rapid elbow flexion drives the fist upward

Extension at the Elbow (Push-Up / Chest Pass)

When you extend (straighten) your elbow — for example, during a push-up or a netball chest pass — you are still using a third class lever, but now the triceps provides the effort.

Component	What It Is
Fulcrum (F)	Elbow joint
Effort (E)	Triceps brachii muscle (inserts on the olecranon process of the ulna, close to the elbow joint)
Load (L)	Weight of the forearm + whatever is being pushed (body weight in a push-up, ball in a chest pass)

Order: F — E — L (Third class)

Sporting examples of elbow extension:

Sport	Action	Description
Gymnastics	Push-up / handstand	Triceps extend the elbow to push the body up
Netball	Chest pass	Arms extend to push the ball forward
Basketball	Chest pass	Same as netball — elbow extension propels the ball
Shot put	Release	Extension at the elbow pushes the shot forward
Rugby	Push in a scrum	Arms extend against the opposing pack

Exam Tip: Both flexion and extension at the elbow use third class levers. The only difference is which muscle provides the effort: biceps for flexion, triceps for extension.

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Lever System at the Knee

Extension at the Knee (Kicking / Squatting)

When you extend (straighten) your knee — for example, when kicking a football or standing up from a squat — you are using a third class lever.

Component	What It Is
Fulcrum (F)	Knee joint
Effort (E)	Quadriceps muscle group (inserts via the patellar tendon on the tibial tuberosity, close to the knee joint)
Load (L)	Weight of the lower leg (shin + foot) + any external load (ball, weight)

Order: F — E — L (Third class)

graph LR
    F["F<br>Knee joint"] --- E["E<br>Quadriceps"] --- L["L<br>Lower leg + ball"]
    style F fill:#e74c3c,color:#fff
    style E fill:#27ae60,color:#fff
    style L fill:#4a90d9,color:#fff

Sporting examples of knee extension:

Sport	Action	Description
Football	Kicking the ball	Powerful knee extension drives the foot into the ball
Rugby	Kicking (penalty, drop goal)	Same principle as football kicking
Gym / Fitness	Squats	Knee extension against body weight or barbell
Athletics	Take-off in long jump	Knee extends powerfully to propel the body upward and forward
Volleyball	Jumping (spike / block)	Knee extension provides the force for the jump
Cycling	Pedal push	Quadriceps extend the knee to push the pedal down

Why the Knee is a Third Class Lever

The quadriceps insert close to the knee joint (via the patellar tendon just below the kneecap). This means the effort is applied close to the fulcrum — placing it between the fulcrum (knee) and the load (lower leg + foot). This arrangement sacrifices power but gives the lower leg a large range of movement and high speed — essential for kicking and running.

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Lever System at the Ankle

Plantarflexion at the Ankle (Rising on Tiptoes / Push-Off in Running)

When you rise onto your tiptoes or push off during running and jumping, you are performing plantarflexion at the ankle. This is the most important example of a second class lever in the body.