What you'll learn
Movement analysis is the study of how the body produces movement, using levers to explain how bones, joints and muscles create force and speed, and planes and axes to describe the direction of movement. In AQA GCSE Physical Education (8582) it is part of Paper 1: The human body and movement in physical activity and sport (1 hour 15 minutes, 78 marks, 30% of the GCSE), and it links closely to the joints and muscles covered in applied anatomy and physiology. This guide explains the three classes of lever and the body's example of each, mechanical advantage, the three planes and three axes of movement with sporting examples, and how to analyse a whole sporting action by combining joint type, movement, lever, plane and axis.
Key terms and definitions
Lever — A rigid bar that turns about a fixed point. In the body, bones are the bars, joints are the fixed points and muscles provide the force.
Fulcrum — The pivot point of a lever; in the body, a joint.
Effort — The force applied to move the lever; in the body, the force from muscle contraction.
Load — The weight or resistance to be moved, such as the weight of a body part or of an object being held.
Effort arm — The distance from the fulcrum to the effort.
Load arm — The distance from the fulcrum to the load.
Mechanical advantage — How efficiently a lever works, found by dividing the effort arm by the load arm. A value above 1 means a large load can be moved with a small effort.
Plane — An imaginary flat surface running through the body, describing the direction of movement.
Axis — An imaginary line about which the body or a body part rotates.
Sagittal plane — Divides the body into left and right halves; movements are forwards and backwards.
Frontal plane — Divides the body into front and back halves; movements are sideways.
Transverse plane — Divides the body into upper and lower halves; movements are rotations.
Core concepts
The three classes of lever
The class of a lever depends on which component is in the middle. A simple memory aid is F-L-E 1-2-3: in a first-class lever the Fulcrum is in the middle; in a second-class lever the Load is in the middle; in a third-class lever the Effort is in the middle.
First-class lever (fulcrum in the middle). The body's example is extension of the neck, such as lifting the head when heading a football upwards. The weight of the head is the load, the joint at the top of the spine is the fulcrum, and the neck muscles provide the effort. First-class levers can increase either force or range, depending on where the fulcrum sits.
Second-class lever (load in the middle). The body's example is plantar flexion at the ankle, such as rising onto the toes or taking off in a jump. The ball of the foot is the fulcrum, the body's weight acts through the ankle as the load, and the gastrocnemius pulls on the heel as the effort. Because the effort arm is longer than the load arm, second-class levers have a high mechanical advantage: they can move a large load (the whole body) with relatively little effort.
Third-class lever (effort in the middle). The body's example is flexion at the elbow, as in a biceps curl. The elbow is the fulcrum, the biceps attaches just below the elbow and provides the effort, and the weight in the hand is the load. The knee also works as a third-class lever when the quadriceps extend the leg in a kick. Most levers in the body are third class.
Mechanical advantage
Mechanical advantage = effort arm ÷ load arm.
- When the effort arm is longer than the load arm (second-class levers), mechanical advantage is high: large loads can be moved with small effort, but the range and speed of movement are limited.
- When the load arm is longer than the effort arm (third-class levers), mechanical advantage is low: more effort is needed, but the lever gives a large range of movement and speed at the end of the limb. This is useful for throwing, striking and kicking, where speed of the hand, foot or implement matters more than force.
Sports equipment can lengthen the load arm further. A tennis racket or golf club extends the arm, so the end of the implement travels faster, increasing the speed of the ball.
Planes and axes
Every movement happens in a plane and about an axis. Each plane is paired with one axis.
| Plane | Axis | Type of movement | Sporting examples |
|---|---|---|---|
| Sagittal | Frontal | Flexion and extension | Running, a front somersault, a forward roll, a biceps curl, a squat |
| Frontal | Sagittal | Abduction and adduction | A cartwheel, a star jump, a side-step |
| Transverse | Vertical (longitudinal) | Rotation | A full-twist jump, a discus or hammer spin, a pirouette, a golf swing |
The frontal axis runs from side to side through the body, like a skewer through the hips, so the body turns forwards or backwards around it in a somersault. The sagittal axis runs from front to back, so the body wheels sideways around it in a cartwheel. The vertical axis runs from head to toe, so the body spins around it in a pirouette.
A common way to remember the pairings is that the plane and axis names "swap": the sagittal plane goes with the frontal axis, and the frontal plane goes with the sagittal axis. The transverse plane goes with the vertical (longitudinal) axis.
Why levers and planes matter to performance
Coaches use lever principles to improve technique. Because a third-class lever trades force for speed, lengthening the load arm makes the end of the limb travel faster: a bowler in cricket keeps the arm straight, and a javelin thrower keeps the throwing arm long, to release the implement at a higher speed. Shortening a lever does the opposite. A sprinter tucks the heel close to the bottom during the recovery phase of the stride, shortening the leg so it can be swung forward more quickly with less effort.
Planes and axes help coaches describe and correct movements precisely. A gymnast who drifts sideways during a forward roll is moving partly out of the sagittal plane; a diver who opens out too early in a twisting dive is slowing their rotation about the vertical axis. Many sporting actions combine movements in more than one plane. A tennis serve, for example, involves rotation of the trunk in the transverse plane as well as extension of the elbow in the sagittal plane, so in exams you should pick out one clear joint action at a time.
Analysing whole sporting actions
Exam questions often ask you to analyse one part of a movement. A full analysis includes:
- The joint and its type (for example, the knee, a hinge joint).
- The articulating bones (femur and tibia).
- The movement (extension).
- The agonist (quadriceps) and antagonist (hamstrings).
- The lever class (third class).
- The plane and axis (sagittal plane, frontal axis).
Practising this sequence with familiar actions such as kicking a ball, a chest pass, a jump shot or a sprint start builds quick, accurate answers.
Worked examples
Example 1: Classifying a lever
Question: Identify the type of lever used at the ankle when a basketball player jumps to shoot, and explain one advantage of this lever. The ankle acts as a second-class lever during plantar flexion: the ball of the foot is the fulcrum, the body weight is the load in the middle, and the gastrocnemius provides the effort. Its effort arm is longer than its load arm, giving a high mechanical advantage, so the player can lift their whole body weight with relatively little effort.
Example 2: Calculating mechanical advantage
A lever has an effort arm of 4 cm and a load arm of 30 cm. Mechanical advantage = 4 ÷ 30 = 0.13 (to two decimal places). Because this is below 1, the lever has a low mechanical advantage: it needs a large effort but gives a wide, fast range of movement, typical of a third-class lever such as the elbow.
Example 3: Identifying plane and axis
Question: A gymnast performs a cartwheel. Identify the plane and axis. A cartwheel moves sideways, so it takes place in the frontal plane about the sagittal axis. In contrast, a front somersault turns forwards, so it takes place in the sagittal plane about the frontal axis.
Example 4: Full movement analysis
Question: Analyse the movement at the knee as a footballer swings the leg through to strike the ball. The knee is a hinge joint between the femur and tibia. As the leg swings through, the knee extends, with the quadriceps as the agonist and the hamstrings as the antagonist. The quadriceps pull on the tibia just below the knee, between the fulcrum (the knee) and the load (the lower leg and foot), so this is a third-class lever: a low mechanical advantage, but a fast, wide swing of the foot. The movement takes place in the sagittal plane about the frontal axis.
Common mistakes and how to avoid them
Do not decide the lever class by which component is at the end. The class depends on what is in the middle: fulcrum (first), load (second), effort (third).
Do not pair planes and axes with the same name. The sagittal plane goes with the frontal axis, and the frontal plane with the sagittal axis.
Do not say third-class levers are "weak" without explaining the benefit. They have a low mechanical advantage but give a large range of movement and speed.
Do not describe a somersault as being in the transverse plane. It is a forward rotation in the sagittal plane about the frontal axis. The transverse plane covers twisting and spinning.
Do not mix up the effort arm and the load arm when calculating mechanical advantage. It is effort arm ÷ load arm.
Exam technique for "Movement analysis"
For lever questions, draw or describe the arrangement in words: name the fulcrum, effort and load for the specific joint in the question, then state the class and the mechanical advantage. For plane and axis questions, give both the plane and the axis, because each is usually worth a mark. In "analyse" questions, follow the sequence of joint, bones, movement, agonist, antagonist, lever, plane and axis, and use the exact terms from the specification. Where a question gives a sporting action you have not practised, break it into the joint movements involved and analyse one at a time.
Quick revision summary
- First class: fulcrum in the middle; neck extension (heading a ball).
- Second class: load in the middle; plantar flexion at the ankle (rising onto the toes); high mechanical advantage.
- Third class: effort in the middle; elbow flexion (biceps curl); low mechanical advantage but large range and speed.
- Mechanical advantage = effort arm ÷ load arm.
- Sagittal plane, frontal axis: flexion and extension (running, front somersault).
- Frontal plane, sagittal axis: abduction and adduction (cartwheel, star jump).
- Transverse plane, vertical axis: rotation (full-twist jump, discus spin).
- Analyse with joint, bones, movement, muscles, lever, plane and axis.