Syllabus coverage
- The location and role of latissimus dorsi, trapezius, deltoid, pectorals, biceps, triceps, abdominals, gluteals, hip flexors, hamstring group (not individual names), quadriceps group (not individual names), gastrocnemius, tibialis anterior
- The role of tendons
- Antagonistic muscle action at the shoulder, elbow, hip, knee and ankle: the action of agonists (prime movers) and antagonists
- How muscles and muscle groups work using isotonic (concentric / eccentric) and isometric contractions
- The differences between slow and fast twitch muscle fibre types with reference to physical activities, limited to force created, fatigue tolerance and aerobic/anaerobic energy supply
Part of the IGCSE PE 0413 syllabus 0413 / 0995.
The 13 muscles you must know
Cambridge names thirteen muscles and muscle groups. You need their location (where they are) and their role (what movement they produce) - so learn them against a body you can picture, not as a list.
Note that Cambridge deliberately says hamstring group and quadriceps group, with no individual names. Writing "biceps femoris" will not gain you anything extra, and the syllabus does not ask for it.
| Muscle | Location | Role |
|---|---|---|
| Latissimus dorsi | Broad muscle across the lower back, either side of the spine | Adducts, extends and rotates the arm at the shoulder - the pulling muscle in swimming and rowing |
| Trapezius | Upper back and neck, running from the base of the skull across to the shoulders | Raises and rotates the scapula, holding the shoulders up and back; works with the deltoid to move the shoulder |
| Deltoid | The rounded muscle covering the top of the shoulder | Abducts the arm (raises it out to the side); the main muscle for lifting the arm |
| Pectorals | Chest, across the upper front of the ribcage | Adducts and flexes the arm at the shoulder - pushes the arm forward and across the body |
| Biceps | Front of the upper arm, between the shoulder and elbow | Flexes the arm at the elbow, bending it |
| Triceps | Back of the upper arm, between the shoulder and elbow | Extends the arm at the elbow, straightening it |
| Abdominals | Front of the torso, between the ribs and the pelvis | Flexes the trunk forwards and rotates it; stabilises the core, keeping the body balanced |
| Gluteals | The buttocks at the back of the hip | Extends and rotates the leg at the hip - the power muscle for pushing off and sprinting |
| Hip flexors | Front of the hip, where the thigh meets the pelvis | Flexes the leg at the hip, raising the knee |
| Hamstring group | Back of the thigh, between the hip and the knee | Flexes the leg at the knee (bending it) and extends the leg at the hip |
| Quadriceps group | Front of the thigh, between the hip and the knee | Extends the leg at the knee, straightening it; the main muscle for kicking and jumping |
| Gastrocnemius | The calf, at the back of the lower leg | Plantar flexes the foot at the ankle, pointing the toes - the push-off muscle for running and jumping |
| Tibialis anterior | Front of the lower leg, beside the shin | Dorsiflexes the foot at the ankle, pulling the toes up towards the shin |
Tendons: how a muscle moves a bone
A muscle cannot act on a bone directly. It pulls through a tendon.
A tendon is a tough, inelastic band of fibrous tissue that joins muscle to bone. Because it does not stretch, it transmits the force generated by the muscle's contraction straight to the bone, which then acts as a lever and moves the joint.
- Tendon = muscle to bone, transmits force to create movement.
- Ligament = bone to bone, holds the joint stable.
- Tendons attach at either end of a muscle, across a joint, which is why a contraction on one side produces movement on the other side of that joint.
- Because tendons are strong and inelastic, the full force of the contraction reaches the bone rather than being absorbed.
Antagonistic muscle action: why muscles come in pairs
A muscle can only contract and pull - it cannot push a bone back to its starting position. So to move a joint back and forth, muscles must work in pairs: while one contracts, the other relaxes.
The muscle that is contracting and doing the work is the agonist or prime mover. The muscle that relaxes and lengthens on the other side of the joint is the antagonist.
Their roles swap when the movement reverses. This is called antagonistic muscle action.
| Joint | Movement | Agonist (prime mover) | Antagonist |
|---|---|---|---|
| Shoulder | Abduction (arm raised out to the side) | Deltoid | Latissimus dorsi (with the pectorals) |
| Elbow | Flexion (arm bent) | Biceps | Triceps |
| Elbow | Extension (arm straightened) | Triceps | Biceps |
| Hip | Flexion (knee raised up in front) | Hip flexors | Gluteals |
| Hip | Extension (leg driven backwards) | Gluteals | Hip flexors |
| Knee | Extension (leg straightened) | Quadriceps group | Hamstring group |
| Knee | Flexion (leg bent / heel drawn up) | Hamstring group | Quadriceps group |
| Ankle | Plantar flexion (toes pointed, push-off) | Gastrocnemius | Tibialis anterior |
| Ankle | Dorsiflexion (toes pulled up) | Tibialis anterior | Gastrocnemius |
Isotonic and isometric contractions
When the agonist contracts, Cambridge wants you to say which type of contraction it is. There are two families: isotonic (the muscle changes length) and isometric (it does not).
Isotonic contractions are the ones that produce sport's big movements, and they come in two forms. Concentric: the muscle shortens as it contracts, producing movement and generating force. Eccentric: the muscle lengthens under tension while still contracting - it is controlling a movement rather than driving it, and it is the type that causes most muscle soreness.
| Contraction type | What the muscle does | Force produced | Example |
|---|---|---|---|
| Isotonic - concentric | Shortens while contracting | Produces movement and generates force | The quadriceps shorten to straighten the knee as a footballer kicks the ball |
| Isotonic - eccentric | Lengthens under tension while still contracting | Controls and slows movement; absorbs force | The quadriceps lengthen under tension as the footballer lands from a jump, controlling the bend of the knee |
| Isometric | Stays the same length; no movement at the joint | Holds a position; produces force but no movement | A gymnast holding a still handstand, with the muscles of the trunk and shoulders working to hold the position |
Slow twitch and fast twitch muscle fibres
Muscles are made of different fibre types, and each type suits a different kind of activity. Cambridge limits this to three differences - force created, fatigue tolerance and aerobic/anaerobic energy supply - so keep your answer to those three headings.
Do not write about mitochondria numbers, myoglobin, colour or capillary density: the syllabus does not ask for it, and it will not earn marks.
- Slow twitch suits endurance events: a cross-country runner or a competitive swimmer over distance.
- Fast twitch suits explosive events: a sprinter in track and field, or a weightlifter in weight training for fitness.
- Most activities use both, but one type dominates depending on the duration and intensity of the effort.
| Slow twitch fibres | Fast twitch fibres | |
|---|---|---|
| Force created | Low force - they contract more slowly and cannot generate much power | High force - they contract quickly and powerfully for short bursts |
| Fatigue tolerance | Fatigue slowly; they can keep working for a long time | Fatigue quickly; they cannot sustain work for long |
| Energy supply | Aerobic - they use oxygen to release energy, so they suit longer, lower-intensity work | Anaerobic - they release energy without oxygen, so they suit short, high-intensity work |
Building a full-mark answer
The reliable structure for any muscle question is: joint → movement → agonist → antagonist → contraction type → link to the activity.
For fibre-type questions use: name the fibre → the relevant difference → which activity it suits and why.
If you are asked to explain, every point needs a consequence attached. Fact, consequence, sporting application - in that order.
Key terms you must be able to define
- Agonist (prime mover)
- The muscle or muscle group that contracts to create a movement, acting as the prime mover at that joint.
- Antagonist
- The muscle or muscle group that relaxes and lengthens on the opposite side of the joint, allowing the agonist's movement to happen and controlling it.
- Antagonistic muscle action
- Muscles working in pairs, one contracting as the other relaxes, so a joint can be moved in two directions.
- Tendon
- Tough, inelastic fibrous tissue that joins muscle to bone and transmits the force of a contraction to the bone to create movement.
- Isotonic contraction
- A contraction in which the muscle changes length, producing movement at a joint. It may be concentric (shortening) or eccentric (lengthening under tension).
- Concentric contraction
- An isotonic contraction in which the muscle shortens while contracting, generating force to create movement.
- Eccentric contraction
- An isotonic contraction in which the muscle lengthens under tension while still contracting, controlling the movement and absorbing force.
- Isometric contraction
- A contraction in which the muscle stays the same length, producing force but no movement at the joint - used to hold a position.
- Slow twitch fibres
- Muscle fibres that create low force, fatigue slowly and use aerobic energy supply, suited to longer, lower-intensity activities.
- Fast twitch fibres
- Muscle fibres that create high force, fatigue quickly and use anaerobic energy supply, suited to short, high-intensity activities.
- Quadriceps group
- The muscle group at the front of the thigh that extends the knee.
- Hamstring group
- The muscle group at the back of the thigh that flexes the knee and extends the hip.
Applied to your sport
Cambridge requires you to apply this knowledge to physical activities. Use these as models, then write your own for the sport you play.
As the player kicks, the quadriceps (agonist) contract concentrically to extend the knee while the hamstrings (antagonist) relax and lengthen. As they land from a jump, the same quadriceps work eccentrically, lengthening under tension to control the bend of the knee.
In front crawl, the latissimus dorsi pulls the arm down and back through the water, while the deltoid returns the arm overhead at the shoulder. Long-distance swimmers rely on slow twitch fibres for continual aerobic work.
Jumping for a rebound, the gastrocnemius (agonist) contracts to plantar flex the ankle while the tibialis anterior (antagonist) relaxes; the arms are held at a set position by isometric contraction of the shoulder muscles.
A player driving backwards to create space extends the hip with the gluteals (agonist) while the hip flexors relax, then flexes the hip with the hip flexors to drive forwards again.
A sprinter in the 100 m uses fast twitch fibres, which contract quickly and powerfully for a short burst but tire rapidly. A cross-country runner over a long distance uses slow twitch fibres, which create less force but use oxygen and keep working without tiring.
Flashcards
Click a card to flip it. Mark honestly — the tracker uses this.
Exam-style questions
8 questions, 24 marks. Write your answer, then reveal the mark scheme and tick each point you actually made. Answering honestly here is what makes the rest of the site useful.
Mark scheme — tick each point you actually made
Mark scheme — tick each point you actually made
Mark scheme — tick each point you actually made
Mark scheme — tick each point you actually made
Mark scheme — tick each point you actually made
Mark scheme — tick each point you actually made
Mark scheme — tick each point you actually made
Mark scheme — tick each point you actually made
Exam technique for this topic
- Always name the joint and the movement alongside the muscle: "biceps as agonist for flexion at the elbow" scores; "biceps" on its own may not.
- For 2-mark explain questions, the second mark usually comes from the antagonist relaxing - remember to include both muscles of the pair.
- Connect contraction type to the action: if the joint moves, it is isotonic; if the joint holds still, it is isometric.
- For muscle fibre questions, stick to the three syllabus headings - force created, fatigue tolerance, aerobic/anaerobic supply. Extra detail from beyond the syllabus earns nothing.
- Only use activities from the syllabus list. Football, Swimming, Basketball, Netball, Athletics, Gymnastics and the rest of the listed activities are all safe.
Why students lose marks here
Where this fits in IGCSE PE 0413
This page is one topic of Cambridge IGCSE PE 0413 / 0995. IGCSE PE 0413 is the course home: every area and every topic in Cambridge's own order, the papers you sit and what each one tests, and the exam-practice tools. The full topic list, with each topic linked to its revision page, is on the IGCSE PE 0413 syllabus page.