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.
With oxygen, and without
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
Put these activities in order from the MOST aerobic to the MOST anaerobic.
- A three-hour marathon
- A 1500 metre run
- A 400 metre run
- A 100 metre sprint
Coach the sprinter
A coach is preparing an athlete for the 100 metre sprint. Help them apply the energy systems.
- Which energy system does an all-out 100 metre sprint mainly use?
- What by-product will build up in the muscles during the sprint?
- Which fuel powers this anaerobic effort?
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
Aerobic against anaerobic
Tap the TWO statements that are TRUE.
- Aerobic exercise uses oxygen to release energy over a long, steady effort.
- Anaerobic exercise can keep going for hours without tiring.
- Lactic acid builds up in the muscles during intense anaerobic exercise.
- Fats are the main fuel for a short, all-out sprint.
- Carbon dioxide and water are the by-products of anaerobic exercise.
Explain the difference
Explain the difference between aerobic and anaerobic exercise. Write in full sentences, describing the aerobic process in prose rather than as a word equation.
- Explain what aerobic exercise is, including the role of oxygen and its by-products
- Explain what anaerobic exercise is and name its by-product
- Give one example activity for each type
- Explain which fuels power each type of exercise