Aerobic and Anaerobic Exercise
Jog for an hour or sprint for ten seconds: your muscles get energy in two very different ways. Learn how the aerobic and anaerobic systems work, what they produce, and what fuels them.
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Aerobic or anaerobic? 🫁
Whether you jog for an hour or sprint for ten seconds, your muscles need **energy**. How they get it depends on whether **oxygen** can keep up with the effort. Your body uses two energy systems: the **aerobic** system, which works **with oxygen**, and the **anaerobic** system, which works when there is **not enough oxygen**.
The language of energy 🔑
Four ideas run through this topic:
Two energy systems ⚖️
Your muscles can release energy in two ways. A strong answer describes each one in full sentences.
Match each term to what it means 🔗
- Aerobic exercise
- Anaerobic exercise
- Lactic acid
- Carbohydrates
- Releases energy using oxygen over a long, steady effort
- Releases energy without enough oxygen in short, intense bursts
- The by-product that builds up in muscles during anaerobic work
- The only fuel that powers both aerobic and anaerobic activity
Which activity is aerobic? 🏃
Which of these activities is mainly AEROBIC?
- Running a marathon at a steady pace
- Sprinting 100 metres flat out
- Lifting the heaviest weight you can once
- Throwing a shot put as far as possible
Which describe anaerobic exercise? ⚡
Select the TWO statements that describe ANAEROBIC exercise.
- Energy is released without enough oxygen
- Lactic acid builds up as a by-product
- It suits long, steady activity like jogging
- Carbon dioxide and water are the main by-products
What fuels each system? 🍌
Both energy systems burn **carbohydrates**, but only **aerobic** exercise can also burn **fats**, because fats need oxygen to release their energy. So during a short, intense sprint your body relies on carbohydrates. **Grade-9 tip:** describe the aerobic process in **full sentences**, that glucose and oxygen release energy, producing carbon dioxide and water, rather than just filling gaps in a word equation.
Complete the summary 🧩
Aerobic exercise happens _____ oxygen and suits _____ intensity activity over a long time. Anaerobic exercise happens without enough oxygen, so the by-product is _____ acid, which builds up during short bursts of _____ intensity effort. Carbohydrates fuel both systems, but _____ can only fuel aerobic activity.
From aerobic to anaerobic 🪜
An interactive activity.
Coach the sprinter 🧭
An interactive activity.
What builds up in the muscles? 🧪
During anaerobic exercise, which by-product builds up in the muscles?
- Lactic acid
- Carbon dioxide and water
- Extra oxygen
- Glucose
Spot the true statements 🖍️
An interactive activity.
Explain the difference ✍️
An interactive activity.