First, Second and Third Class Levers

This lesson introduces the three classes of lever as required by the Edexcel GCSE PE specification (1PE0 — Topic 1: Applied Anatomy and Physiology). The human body contains hundreds of lever systems — every time you move a limb, you are using a lever. Understanding how levers work allows you to analyse sporting movements and explain why certain joints and muscles are suited to certain actions. This lesson covers the three components of every lever system, the three classes of lever, and how to identify them using body and everyday examples.

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What Is a Lever?

A lever is a rigid bar that turns around a fixed point when a force is applied. In the human body:

• The rigid bar is a bone.
• The fixed point is a joint.
• The force is provided by a muscle.

Every lever system has exactly three components:

Component	What It Represents in the Body	Symbol
Fulcrum (F)	The joint — the pivot point around which the lever rotates	F
Load (L)	The resistance being moved — the weight of the body part, an object, or an opponent	L
Effort (E)	The force applied by the muscle to move the load	E

Exam Tip: Edexcel examiners expect you to identify the fulcrum, load and effort in any lever system. Always think: F = joint, L = weight/resistance, E = muscle force. If you are asked to "label" a lever diagram, these are the three labels you need.

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The Three Classes of Lever

The class of a lever is determined by the arrangement of the fulcrum, load and effort. There are three possible arrangements.

First Class Lever — Fulcrum in the Middle

In a first class lever, the fulcrum is positioned between the effort and the load.

Arrangement: Effort — Fulcrum — Load

graph LR
    E["Effort<br>(E)"] --- F["Fulcrum<br>(F)"] --- L["Load<br>(L)"]
    style E fill:#27ae60,color:#fff
    style F fill:#e74c3c,color:#fff
    style L fill:#4a90d9,color:#fff

Everyday example: A seesaw. The pivot (fulcrum) is in the centre, with effort pushing down on one side and the load being lifted on the other.

Body example: Extension at the neck (nodding the head backwards).

• Fulcrum: The atlanto-occipital joint (where the skull meets the top of the spine).
• Effort: The muscles at the back of the neck pulling downward on the back of the skull.
• Load: The weight of the face and front of the skull, pulled forward by gravity.

Component	In the Body
Fulcrum (F)	Atlanto-occipital joint (top of spine)
Effort (E)	Neck extensor muscles (pulling down at the back)
Load (L)	Weight of the face and front of the skull

Key feature: First class levers can change the direction of a force and provide balance. They are relatively rare in the human body.

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Second Class Lever — Load in the Middle

In a second class lever, the load is positioned between the fulcrum and the effort.

Arrangement: Fulcrum — Load — Effort

graph LR
    F["Fulcrum<br>(F)"] --- L["Load<br>(L)"] --- E["Effort<br>(E)"]
    style F fill:#e74c3c,color:#fff
    style L fill:#4a90d9,color:#fff
    style E fill:#27ae60,color:#fff

Everyday example: A wheelbarrow. The wheel (fulcrum) is at one end, the heavy load is in the middle, and you lift (effort) at the handles.

Body example: Plantarflexion at the ankle (rising onto tiptoes).

• Fulcrum: The ball of the foot (the point where the foot contacts the ground).
• Load: Body weight pushing down through the ankle joint (the tibia).
• Effort: The gastrocnemius (calf muscle) pulling upward on the heel via the Achilles tendon.

Component	In the Body
Fulcrum (F)	Ball of the foot (ground contact point)
Load (L)	Body weight acting downward through the ankle
Effort (E)	Gastrocnemius pulling up on the heel (Achilles tendon)

Key feature: Second class levers are power levers. The effort arm is always longer than the load arm, which means a large load can be moved with relatively less effort. This is why the calf muscles can lift the entire body weight when you rise onto tiptoes.

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Third Class Lever — Effort in the Middle

In a third class lever, the effort is positioned between the fulcrum and the load.

Arrangement: Fulcrum — Effort — Load

graph LR
    F["Fulcrum<br>(F)"] --- E["Effort<br>(E)"] --- L["Load<br>(L)"]
    style F fill:#e74c3c,color:#fff
    style E fill:#27ae60,color:#fff
    style L fill:#4a90d9,color:#fff

Everyday example: A pair of tweezers or a fishing rod. The pivot is at one end, the force is applied in the middle, and the object being moved is at the far end.

Body example: Flexion at the elbow (e.g. a bicep curl).

• Fulcrum: The elbow joint.
• Effort: The biceps brachii muscle, which inserts on the radius just below the elbow.
• Load: The weight held in the hand (or the weight of the forearm and hand).

Component	In the Body
Fulcrum (F)	Elbow joint
Effort (E)	Biceps brachii (inserts on radius, close to elbow)
Load (L)	Weight in the hand / weight of the forearm

Key feature: Third class levers are speed and range of movement levers. A small contraction of the muscle close to the fulcrum produces a large, fast movement at the far end (the load). However, this comes at the cost of power — more effort is needed to move the load compared to a second class lever.

Exam Tip: Third class levers are the most common lever class in the human body. Most limb movements — bicep curls, kicking, throwing, striking — use third class levers because the body is designed to prioritise speed and range of movement over brute force.

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Summary Comparison Table

Feature	First Class	Second Class	Third Class
Arrangement	E — F — L	F — L — E	F — E — L
What is in the middle?	Fulcrum	Load	Effort
Body example	Nodding the head (neck)	Rising on tiptoes (ankle)	Bicep curl (elbow)
Everyday example	Seesaw	Wheelbarrow	Tweezers / fishing rod
Main advantage	Balance, direction change	Power (large load, less effort)	Speed and range of movement
How common in body?	Rare	Uncommon	Very common

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Mnemonic: "1-2-3, F-L-E"

Think of the word FLE (Fulcrum, Load, Effort). For each class, the component in the middle shifts:

• 1st class: Fulcrum in the middle → FLE
• 2nd class: Load in the middle → FLE
• 3rd class: Effort in the middle → FLE

This gives you the order 1-2-3 = F-L-E. The middle letter changes each time.

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Common Exam Mistakes

• Mixing up the three classes — use the FLE mnemonic to remember which component is in the middle for each class.
• Confusing effort and load — the effort is ALWAYS the muscle force; the load is ALWAYS the resistance/weight being moved.
• Forgetting to identify the fulcrum as a joint — in the body, the fulcrum is always a joint (not a bone or a muscle).
• Not knowing the key body example for each class — first class = neck (nodding), second class = ankle (rising on tiptoes), third class = elbow (bicep curl). Learn these three.
• Saying second class levers are the most common — third class levers are by far the most common in the human body.

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Summary

• Every lever system has three components: fulcrum (joint), load (resistance/weight), and effort (muscle force).
• First class lever: Fulcrum in the middle (E–F–L). Body example: extension at the neck. Advantage: balance and direction change. Rare in the body.
• Second class lever: Load in the middle (F–L–E). Body example: rising on tiptoes at the ankle. Advantage: power. Uncommon in the body.
• Third class lever: Effort in the middle (F–E–L). Body example: bicep curl at the elbow. Advantage: speed and range of movement. The most common class in the body.
• Use the FLE mnemonic (1st = F in middle, 2nd = L in middle, 3rd = E in middle) to remember each class.