Mini-Lesson

Fitness & Body Systems

This mini-lesson covers Edexcel GCSE PE Component 1 — Fitness & Body Systems: the musculo-skeletal and cardio-respiratory systems, aerobic and anaerobic exercise, the short- and long-term effects of exercise, movement analysis (levers, planes and axes) and the principles of training.

There are a few calculations — cardiac output, mechanical advantage and target heart-rate zones. Work through each screen, answer the questions as you go and collect ⭐ stars. Press Start when you're ready.

Musculo-skeletal

The musculo-skeletal system

The skeleton supports and protects the body, allows movement, stores minerals and makes blood cells in the marrow. Bones meet at joints.

Most joints used in sport are synovial joints. Don't confuse these two:

Ligaments join bone to bone (stability).
Tendons join muscle to bone (transfer the pull).
Cartilage cushions and reduces friction; synovial fluid lubricates.

Muscles work in antagonistic pairs: as the agonist contracts, the antagonist relaxes (biceps/triceps at the elbow; quadriceps/hamstrings at the knee).

Quick check

Ligament or tendon?

?Which structure joins one bone to another to keep a joint stable?

Cardio-respiratory

The cardio-respiratory system

The cardiovascular system (heart, blood, vessels) delivers oxygen and removes waste. Arteries carry blood away from the heart, veins carry it back, and capillaries allow gas exchange with the tissues.

cardiac output = stroke volume × heart rateQ (ml/min) = blood per beat × beats per minute

The respiratory system exchanges gases at the alveoli, which have a large surface area, thin walls, a moist lining and a rich blood supply — perfect for fast diffusion of oxygen in and carbon dioxide out.

Calculate

Cardiac output

1An athlete has a stroke volume of 75 ml and a heart rate of 72 bpm. Calculate their cardiac output in ml/min.

ml/min

Hint: cardiac output = stroke volume × heart rate = 75 × 72.

Aerobic & anaerobic

Aerobic & anaerobic exercise

glucose + oxygen → energy (+ CO₂ + water)aerobic — with oxygen, for longer, lower-intensity work

glucose → energy (+ lactic acid)anaerobic — without oxygen, for short, high-intensity work

Aerobic — jogging or distance swimming: lower intensity, sustained, uses oxygen.
Anaerobic — a sprint or a heavy lift: high intensity, short, makes lactic acid, causing oxygen debt (EPOC) repaid afterwards.

Sort it

Put each one in the right group

Tap each activity or fact, then tap whether it is mainly aerobic, mainly anaerobic, or true of both.

🫀 Aerobic

🏃 Anaerobic

🔁 True of both

Effects of exercise

Short-term & long-term effects

Short-term: heart rate, breathing rate and depth rise; body temperature increases; you sweat; muscles may fatigue as lactic acid builds up.

Long-term: the heart enlarges and strengthens (cardiac hypertrophy → higher stroke volume, lower resting HR); more capillaries form; muscles, bones, tendons and ligaments get stronger; recovery is faster.

Quick check

A long-term adaptation

?After months of endurance training an athlete's resting heart rate falls. Which adaptation best explains this?

Levers

Movement analysis — levers

Bones act as levers. The class depends on which part is in the middle:

First class — fulcrum in the middle (nodding the head; elbow extension).
Second class — load in the middle; has mechanical advantage (plantar-flexion / rising onto the toes).
Third class — effort in the middle; most common; mechanical disadvantage (biceps curl).

mechanical advantage = effort arm ÷ load arm

Calculate

Mechanical advantage

2A second-class lever has an effort arm of 50 cm and a load arm of 10 cm. Calculate the mechanical advantage.

: 1

Hint: mechanical advantage = effort arm ÷ load arm = 50 ÷ 10.

Planes & axes

Planes & axes of movement

Sagittal plane / transverse axis — forward rotation (a somersault; a biceps curl).
Frontal plane / sagittal axis — side-to-side movement (a cartwheel).
Transverse plane / longitudinal axis — twisting/spinning (a full turn, a discus spin).

Quick check

Somersault plane

?A trampolinist performs a forward somersault. Which plane and axis is used?

Principles of training

Principles of training & heart-rate zones

Training must be specific and use progressive overload, applied through FITT (Frequency, Intensity, Time, Type). Stop training and fitness is lost (reversibility).

maximum heart rate = 220 − age (bpm)aerobic zone 60–80% · anaerobic zone 80–90% of max HR

Calculate

Aerobic threshold

3A 15-year-old wants the bottom of their aerobic zone, which is 60% of max heart rate. First find max HR (220 − 15), then calculate 60% of it, to the nearest whole bpm.

bpm

Hint: max HR = 205; then 0.6 × 205.

Match it

Match each statement to its answer

Tap a term on the left, then its correct meaning on the right.

Statement

Answer

Recap

The big ideas to know

Joints: ligament = bone-to-bone; tendon = muscle-to-bone; cartilage cushions

Cardio-respiratory: Q = stroke volume × heart rate; alveoli = big area, thin, moist, good blood supply

Energy: aerobic (O₂, long/low) vs anaerobic (no O₂, short/hard → lactic acid, EPOC)

Levers: 1st fulcrum · 2nd load (advantage) · 3rd effort (common); MA = effort ÷ load arm

Planes/axes: sagittal↔transverse · frontal↔sagittal · transverse↔longitudinal

Training: specificity, progressive overload, FITT; max HR = 220 − age

You've covered Edexcel Component 1 — Fitness & Body Systems. Press Finish to see your score.

🏆

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