The musculo-skeletal system and analysis of movement in physical activities — AQA A-Level Physical Education

This topic covers the structure and function of the musculo-skeletal system, including bone types, joint classifications, muscle fibre types, and the roles of tendons, ligaments and cartilage. It also examines how movement is produced and analysed through levers, planes, axes and Newton's laws of motion, giving you the tools to break down any sporting action.

Understanding this topic is essential because it underpins almost every other area of A-Level PE, from biomechanics and skill acquisition to sports psychology and exercise physiology. AQA examiners frequently test your ability to apply anatomical knowledge to unfamiliar sporting examples, so memorising definitions alone is not enough. You must be able to analyse movement accurately using correct terminology.

• →The skeleton has five key functions: support, protection, movement, mineral storage and blood cell production. Bones are classified as long, short, flat, irregular or sesamoid, each suited to a specific role.
• →Joints are classified as fibrous (immovable), cartilaginous (slightly movable) or synovial (freely movable). Synovial joints contain cartilage, synovial fluid, a joint capsule, bursae and ligaments, and include hinge, ball-and-socket, pivot, saddle, condyloid and gliding types.
• →Muscles work in antagonistic pairs: the agonist (prime mover) contracts concentrically to produce movement, while the antagonist relaxes and lengthens. Isotonic contractions include concentric and eccentric phases, while isometric contractions produce no movement.
• →Levers consist of a fulcrum, effort and load. First-class levers have the fulcrum in the middle, second-class levers have the load in the middle, and third-class levers have the effort in the middle. Most levers in the human body are third-class and work at a mechanical disadvantage.
• →Movement occurs in three planes (sagittal, frontal, transverse) about three axes (transverse, sagittal, longitudinal). Newton's laws of motion explain how force, mass and acceleration interact during sporting actions.

• Bones act as levers and joints act as fulcrums in the musculo-skeletal system.
• Muscles provide the effort that moves the lever, while body weight or an external load provides resistance.
• Tendons attach muscle to bone and transmit force; ligaments connect bone to bone and stabilise joints.
• Antagonistic muscle pairs work reciprocally so one muscle contracts while the other relaxes and lengthens.
• Concentric, eccentric and isometric contractions produce different movement outcomes at a joint.
• Application requires naming a specific sporting action, the joint involved, the agonist, the antagonist and the movement produced.
• The sagittal plane divides the body into left and right portions and permits forward and backward movement.
• The transverse axis runs horizontally from side to side and is the axis about which sagittal-plane rotation occurs.
• Flexion decreases the angle at a joint, for example the elbow during the upward phase of a biceps curl.
• Extension increases the angle at a joint, for example the elbow during the downward phase of a biceps curl.
• Dorsiflexion at the ankle lifts the toes towards the shin, while plantar flexion points the toes away from the shin.
• A complete analysis names the joint, the action, the plane and the axis, for example knee extension in the sagittal plane about a transverse axis.
• The shoulder is a ball-and-socket joint that permits flexion, extension and hyperextension in the sagittal plane about a transverse axis.
• The hip is a ball-and-socket joint that permits flexion, extension and hyperextension in the sagittal plane about a transverse axis.
• Shoulder flexion raises the arm forwards, for example during the upward phase of a front raise.
• Shoulder extension returns the arm from flexion towards the anatomical position, for example during the downward phase of a front raise.
• Shoulder hyperextension moves the arm backwards beyond the anatomical position, for example during the pull phase of a rowing stroke.
• Hip flexion lifts the thigh forwards, for example during the knee lift in running.
• Hip extension drives the thigh backwards, for example during the push-off phase of sprinting.
• Hip hyperextension carries the thigh further backwards beyond the anatomical position, for example in the trailing leg of a hurdler.
• The elbow is a hinge joint that allows flexion and extension only.
• The knee is a hinge joint that allows flexion and extension only.
• Flexion decreases the angle between the bones at the joint.
• Extension increases the angle between the bones at the joint, straightening the limb.
• At the elbow, flexion brings the forearm towards the upper arm, for example in the upward phase of a biceps curl.
• At the knee, flexion brings the lower leg towards the back of the thigh, for example in the recovery phase of a running stride.
• Extension at the knee straightens the leg, for example in the drive phase of a jump.
• The ankle is a hinge joint that allows plantar flexion and dorsiflexion.
• Plantar flexion points the toes downwards and away from the shin.
• Dorsiflexion pulls the toes upwards towards the shin.
• Plantar flexion occurs at take-off in a jump or when rising onto the balls of the feet.
• Dorsiflexion occurs as the heel strikes the ground during walking or running.
• Dorsiflexion prepares the foot to absorb landing forces.
• The two movements are opposites and occur in the same plane at the ankle.
• A plane is an imaginary flat surface through which a body part moves; an axis is the line about which rotation occurs.
• The frontal (coronal) plane divides the body into front and back portions, and movement within it occurs side to side.
• The sagittal axis runs front to back through the body and lies perpendicular to the frontal plane.
• Frontal-plane actions about the sagittal axis include abduction and adduction at the shoulder and hip, and inversion and eversion at the ankle.
• To analyse a movement, identify the joint action first, then the plane containing it, then the axis at right angles to that plane.
• Abduction is movement of a limb away from the midline of the body.
• Adduction is movement of a limb towards or across the midline of the body.
• Both abduction and adduction occur at the shoulder and at the hip.
• These actions take place in the frontal plane about the sagittal axis.
• In analysis, the joint is named first, then the direction of movement relative to the midline determines whether the action is abduction or adduction.
• The transverse plane divides the body into upper and lower portions.
• The longitudinal axis runs vertically from head to feet.
• Rotation is the joint action occurring in the transverse plane about the longitudinal axis.
• Transverse-plane rotation turns a limb or the trunk in a horizontal arc.
• Circumduction combines flexion, extension, abduction and adduction, and does not include rotation.
• Plane, axis and action must be identified consistently when analysing a movement.
• Horizontal abduction and adduction occur at the shoulder and the hip.
• The limb must be raised to approximately 90 degrees for the action to be described as horizontal.
• Horizontal abduction moves the limb away from the midline of the body.
• Horizontal adduction moves the limb towards or across the midline of the body.
• These actions occur in the transverse plane about the longitudinal axis.
• A sporting example, such as the racquet arm in a tennis forehand drive, can be used to illustrate the actions.
• Identifies a named joint type, such as hinge at the elbow or ball-and-socket at the shoulder, and links it to the movement it permits.
• Names the articulating bones at a stated joint, for example humerus, radius and ulna at the elbow, or humerus and scapula at the shoulder.
• Defines the agonist as the muscle that contracts to produce or control the movement and the antagonist as the muscle that relaxes to allow it.
• Applies the agonist–antagonist pairing to a named action, such as biceps brachii as agonist and triceps brachii as antagonist during elbow flexion.
• Recognises that during the downward phase of a movement controlled by gravity, the agonist remains the same but works eccentrically.
• Distinguishes isotonic contraction (concentric and eccentric) from isometric contraction, where tension develops without joint movement.
• Defines isotonic contraction as contraction in which the muscle changes length and a joint moves.
• Defines concentric contraction as the muscle shortening under tension to produce movement, for example the biceps brachii during elbow flexion.
• Defines eccentric contraction as the muscle lengthening under tension while controlling movement, for example the biceps brachii during elbow extension.
• Defines isometric contraction as the muscle developing tension without changing length and without joint movement, for example holding a plank.
• Applies the correct term to a described action, such as labelling the lowering phase of a biceps curl as eccentric.
• Recognises that the same muscle can act concentrically and eccentrically in different phases of one movement.

• 💡Use a clear structure for each example: joint, agonist, antagonist, contraction type, movement and sporting context.
• 💡Choose a range of physical activities, such as a sprint start, a netball pass and a rugby scrum, to show breadth.
• 💡Link each anatomical point back to the demand of the exercise, such as generating force, absorbing impact or maintaining stability.
• 💡Use the structure 'joint + action + plane + axis' in every analysis answer, for example 'extension at the knee in the sagittal plane about a transverse axis'.
• 💡Sketch a simple stick figure with a side-on view to check that the movement is forwards or backwards before committing to the sagittal plane.
• 💡Link each action to a named sporting example, such as the knee during the kicking action in football, to show applied understanding.
• 💡Check that the axis is perpendicular to the plane: sagittal plane pairs with transverse axis, frontal plane with sagittal axis, transverse plane with longitudinal axis.
• 💡Use the structure 'joint + action + plane + axis' for every analysis, for example 'hip extension in the sagittal plane about a transverse axis'.
• 💡Choose a clear sporting example for each action, such as shoulder hyperextension in the pull phase of rowing or hip hyperextension in the trailing leg of a hurdler.
• 💡Check the direction of movement against the anatomical position: if the limb moves beyond it, the action is hyperextension, not extension.
• 💡Remember that the shoulder and hip are ball-and-socket joints, so they can also move in other planes; state the plane explicitly to show you are analysing the sagittal action.
• 💡Read the stem carefully to identify which joint is named, then eliminate options that describe movements of the other joint.
• 💡Check the direction of the movement described: if the angle at the joint is getting smaller, the answer is flexion; if it is getting larger, the answer is extension.
• 💡Link each option to a familiar action, such as a biceps curl for the elbow or a squat for the knee, to test whether the movement named matches the action.
• 💡Picture the foot in the position described in the stem: toes down means plantar flexion, toes up means dorsiflexion.
• 💡Eliminate options that name movements of the knee or hip, because the stem asks specifically about the ankle.
• 💡Use a familiar action such as standing on tiptoe or a heel strike to check which movement the option describes.
• 💡Learn each plane with its perpendicular axis as a paired fact, for example frontal plane with sagittal axis, so a question naming one immediately prompts the other.
• 💡When a question describes a skill, name the joint action first, then state the plane containing that action, then give the axis at right angles to it.
• 💡Use a physical check: if the limb moves sideways away from or towards the midline, the action is in the frontal plane about the sagittal axis.
• 💡Use the memory link that abduction takes the limb away from the body and adduction adds it back towards the midline.
• 💡For each example, name the joint, state the direction of movement relative to the midline, then give the action, plane and axis in that order.
• 💡Check both the shoulder and the hip when revising, since a question may ask about either joint or ask you to compare the two.
• 💡State the plane, then the axis, then the action in that order so each element of the analysis is explicit.
• 💡Check that the named axis is perpendicular to the named plane before committing to an answer.
• 💡Use a concrete sporting example, such as trunk rotation in a golf swing, to test whether the action really occurs in the transverse plane.
• 💡Check that the limb is raised to about 90 degrees before labelling the action as horizontal.
• 💡State the direction of travel relative to the body's midline to distinguish abduction from adduction.
• 💡Link the action to the transverse plane and longitudinal axis to show a complete movement analysis.
• 💡Read the stem carefully to identify which joint and which phase of movement are being asked about before choosing an option.
• 💡For agonist–antagonist items, decide the direction of movement and the role of gravity first, then assign the controlling muscle as agonist.
• 💡Check each option against the definition of the joint type or contraction type rather than choosing the longest or most familiar-sounding option.
• 💡Where an option names bones, confirm that every named bone genuinely articulates at the joint given in the stem.
• 💡Identify whether the stem describes a joint moving or a position being held before selecting a contraction type.
• 💡For a described action, decide whether the muscle is shortening or lengthening under tension, then match that to concentric or eccentric.
• 💡Check that the option you choose accounts for both muscle length change and joint movement, since these distinguish the contraction types.
• 💡Use a familiar example such as a biceps curl or a plank to test each option against what the muscle is actually doing.
• 💡Always use specific anatomical terminology in your answers. Instead of writing 'the leg muscle contracts', write 'the quadriceps contract concentrically to extend the knee'. This shows precise knowledge and secures application marks.
• 💡When asked to analyse a movement, structure your answer using the 'joint, movement, plane, axis, agonist' framework. This ensures you cover all the required points and makes your answer easy for the examiner to mark.
• 💡For 6-mark extended response questions, use sporting examples that you know well. AQA examiners reward accurate application to sport, so choose examples where you can confidently identify the joint, movement, plane, axis and muscles involved.

• Naming a muscle without naming the joint or movement; correction: always link the muscle to the joint it crosses and the movement it produces.
• Swapping the roles of tendons and ligaments; correction: tendons attach muscle to bone, ligaments attach bone to bone.
• Describing a sporting action without identifying the agonist and antagonist; correction: state which muscle is contracting and which is relaxing.
• Treating all contractions as concentric; correction: identify whether the muscle is shortening, lengthening under tension or holding length.
• Confusing the sagittal plane with the frontal plane: the frontal plane divides the body into front and back and allows sideways movement, whereas the sagittal plane allows forward and backward movement.
• Naming the wrong axis for sagittal-plane movement: the correct axis is transverse (side to side), not longitudinal (top to bottom) or sagittal (front to back).
• Describing flexion and extension as the same action: flexion decreases the joint angle, while extension increases it, so they are opposite movements.
• Forgetting to state the joint when naming an action: 'flexion' alone is incomplete because flexion at the elbow and flexion at the knee are different joint actions.
• Treating hyperextension as the same as extension: extension returns a joint to the anatomical position, while hyperextension continues the movement beyond it.
• Confusing shoulder flexion with shoulder abduction: flexion moves the arm forwards in the sagittal plane, whereas abduction moves it sideways in the frontal plane.
• Naming the wrong axis for shoulder or hip flexion: the correct axis is transverse, not longitudinal or sagittal.
• Describing hip extension as lifting the thigh forwards: hip extension moves the thigh backwards, while hip flexion lifts it forwards.
• Treating the elbow or knee as a ball-and-socket joint: the misunderstanding is that these joints allow rotation and sideways movement, but the correction is that both are hinge joints permitting only flexion and extension.
• Reversing the definitions: the misunderstanding is that flexion straightens the limb, but the correction is that flexion decreases the joint angle and extension increases it.
• Confusing the movement with the muscle producing it: the misunderstanding is that naming the biceps brachii or quadriceps answers a question about movement type, but the correction is that the question asks for the movement, so flexion or extension must be named.
• Applying the wrong phase of an action: the misunderstanding is that the downward phase of a biceps curl is flexion, but the correction is that the downward phase is extension because the elbow angle increases.
• Reversing the two terms: the misunderstanding is that plantar flexion lifts the toes towards the shin, but the correction is that plantar flexion points the toes downwards and dorsiflexion lifts them upwards.
• Treating the ankle as a ball-and-socket joint: the misunderstanding is that the ankle allows sideways movement, but the correction is that it is a hinge joint allowing only plantar flexion and dorsiflexion.
• Confusing ankle movement with knee movement: the misunderstanding is that bending the knee is dorsiflexion, but the correction is that dorsiflexion happens at the ankle when the toes move towards the shin.
• Ignoring the phase of the action: the misunderstanding is that any foot movement in a jump is plantar flexion, but the correction is that the landing phase typically involves dorsiflexion as the foot prepares to absorb force.
• Confusing the sagittal axis with the sagittal plane: the sagittal plane divides the body into left and right portions and contains flexion and extension, whereas the sagittal axis is a front-to-back line about which frontal-plane movements such as abduction rotate.
• Assuming any sideways movement must occur about a vertical axis: raising the arms sideways to a T shape is abduction in the frontal plane, and the rotation is about the sagittal axis, not the longitudinal axis.
• Treating plane and axis as the same idea: a plane describes the surface in which a body part travels, while an axis is the line about which it rotates, and the two are always perpendicular to each other.
• Reversing the definitions: abduction moves a limb away from the midline and adduction moves it towards the midline, so raising the arm sideways to a T shape is abduction, not adduction.
• Believing abduction and adduction occur only at the shoulder: both actions also occur at the hip, for example stepping the leg out to the side is hip abduction.
• Placing these actions in the wrong plane: abduction and adduction are frontal-plane movements about the sagittal axis, not sagittal-plane movements about the frontal axis.
• Confusing the transverse plane with the frontal plane: the frontal plane divides the body into front and back portions, whereas the transverse plane divides it into upper and lower portions.
• Naming the longitudinal axis as horizontal: the longitudinal axis is vertical, running from head to feet, so it is perpendicular to the transverse plane.
• Treating circumduction as including rotation: circumduction combines flexion, extension, abduction and adduction only, without rotation.
• Confusing horizontal abduction with abduction in the frontal plane: horizontal abduction occurs when the limb is raised and moves across in the transverse plane, whereas abduction raises the limb away from the midline in the frontal plane.
• Describing horizontal adduction as moving the limb away from the midline: horizontal adduction brings the limb towards or across the midline.
• Using a standing leg swing as an example of horizontal adduction: a standing leg swing across the body is hip adduction in the frontal plane, not horizontal adduction.
• Naming the antagonist as the muscle that produces the movement: the antagonist relaxes and lengthens to allow the action, while the agonist contracts to produce it.
• Assuming agonist and antagonist roles reverse during the downward phase of a lift: in a biceps curl's downward phase, the biceps remains the agonist working eccentrically to control gravity.
• Listing bones that do not articulate at the stated joint, such as naming the radius and ulna at the shoulder: at the shoulder the humerus articulates with the scapula.
• Confusing joint type with movement: a hinge joint permits flexion and extension in one plane, whereas a ball-and-socket joint permits movement in several planes.
• Believing that eccentric contraction means the muscle is relaxed: the muscle lengthens while still under tension and controlling the movement.
• Assuming isometric contraction involves no muscle activity: tension is developed, but muscle length stays the same and no joint movement occurs.
• Calling any shortening of a muscle concentric regardless of context: concentric contraction requires the muscle to shorten under tension to produce movement.
• Treating a muscle as permanently concentric or eccentric: the same muscle can act concentrically in one phase and eccentrically in the next.
• Students often think the agonist is the muscle that relaxes during a movement. In fact, the agonist is the prime mover that contracts concentrically, while the antagonist relaxes and lengthens to allow the movement.
• Many students believe that all levers in the body give a mechanical advantage. In reality, most levers in the human body are third-class levers, which operate at a mechanical disadvantage but allow greater range of motion and speed.
• Students frequently confuse the plane and axis pairings. Remember: sagittal plane with transverse axis, frontal plane with sagittal axis, and transverse plane with longitudinal axis.

1. 1Days 1-2: Create a labelled diagram of the skeleton and a synovial joint. Memorise the five functions of the skeleton and the six types of synovial joint with a sporting example for each.
2. 2Days 3-4: Learn the antagonistic muscle pairs for the major joints (shoulder, elbow, hip, knee, ankle). Practise identifying the agonist and antagonist for flexion, extension, abduction, adduction, rotation, circumduction, plantarflexion and dorsiflexion.
3. 3Days 5-6: Master levers by drawing first, second and third-class lever diagrams and labelling the fulcrum, effort and load. For each lever type, give a sporting example and state whether it has a mechanical advantage or disadvantage.
4. 4Days 7-8: Learn the three planes and three axes, and practise analysing at least ten different sporting actions using the 'joint, movement, plane, axis, agonist' framework.
5. 5Days 9-10: Complete past paper questions on this topic, focusing on 4-mark and 6-mark extended response questions. Mark your answers using the official mark scheme and identify any gaps in your knowledge.

• 📋Short-answer definition questions (1-2 marks): These ask you to define a term such as 'agonist' or 'synovial joint'. Advice: be precise and use full anatomical terminology rather than everyday language.
• 📋Application questions (4-6 marks): These ask you to analyse a specific sporting action, such as a tennis serve or a rugby tackle. Advice: use the 'joint, movement, plane, axis, agonist' framework and always link back to the sporting example.
• 📋Extended response questions (6-9 marks): These require you to discuss a broader topic, such as how the musculo-skeletal system allows movement in a named sport. Advice: plan your answer, use paragraphs, and include specific anatomical detail and sporting examples throughout.
• 📋Data analysis questions (3-4 marks): These present a table or graph of muscle fibre types or joint angles and ask you to interpret the data. Advice: read the axes carefully, quote specific figures from the data, and link your answer back to the sporting context.