Applying Energy Systems to Sport

This final lesson in the Aerobic and Anaerobic Exercise topic brings everything together. In the AQA GCSE PE exam, you will be expected to apply your knowledge of energy systems to specific sporting scenarios — identifying which system is being used, justifying your answer with reference to intensity and duration, and explaining the physiological effects on the performer. This lesson provides a structured approach to answering these application questions.

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The Key Principle: Intensity and Duration

The energy system used depends on two factors:

Factor	Aerobic	Anaerobic
Intensity	Low to moderate	High to maximal
Duration	Long (minutes to hours)	Short (seconds to ~60 seconds)

These two factors are your primary tools for justifying which energy system is being used. Every exam answer about energy systems should reference at least one of them.

graph TD
    A[Identify the Activity] --> B{What is the<br>INTENSITY?}
    B -->|Low to moderate| C{What is the<br>DURATION?}
    B -->|High to maximal| D{What is the<br>DURATION?}
    C -->|Long - minutes to hours| E[Predominantly<br>AEROBIC]
    C -->|Short burst within<br>longer activity| F[Mix of both -<br>see energy continuum]
    D -->|Short - seconds to<br>~60 seconds| G[Predominantly<br>ANAEROBIC]
    D -->|Sustained high intensity<br>for minutes| F
    style A fill:#4a90d9,color:#fff
    style E fill:#27ae60,color:#fff
    style G fill:#e74c3c,color:#fff
    style F fill:#f39c12,color:#fff

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Sport-by-Sport Analysis

Predominantly Aerobic Sports

These are activities performed at low-to-moderate intensity over an extended period.

Sport/Activity	Typical Duration	Intensity	Why Aerobic?
Marathon	2–5+ hours	Low to moderate	Sustained effort over a very long duration; oxygen supply meets demand
Recreational swimming	20–60 minutes	Low to moderate	Rhythmic, continuous movement at a manageable pace
Road cycling	1–6+ hours	Low to moderate	Prolonged effort; body can maintain oxygen delivery
Hiking / brisk walking	1+ hours	Low	Very low intensity sustained over a long period
Cross-country running	20–40 minutes	Moderate	Sustained running at a pace below maximum

Physiological explanation: In aerobic activities, the body uses the aerobic energy equation: glucose + oxygen → energy + CO2 + water. Because oxygen supply meets demand, there is no significant lactic acid build-up, and the activity can be sustained for long periods.

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Predominantly Anaerobic Sports

These are activities performed at high-to-maximal intensity for a short duration.

Sport/Activity	Typical Duration	Intensity	Why Anaerobic?
100 m sprint	10–12 seconds	Maximal	Flat-out effort; duration far too short for aerobic system to dominate
Shot put	1–2 seconds (throw)	Maximal/explosive	Single explosive action; maximum force for minimum time
Weightlifting (1RM)	A few seconds	Maximal	Maximum load lifted in a single explosive effort
Long jump	~2 seconds (run-up and jump)	Maximal	Short, explosive action requiring maximum power
Javelin throw	~2 seconds (delivery)	Maximal	Explosive release requiring maximum force
Gymnastics vault	~5 seconds	Maximal	Short, explosive run-up and vault

Physiological explanation: In anaerobic activities, the body uses the anaerobic energy equation: glucose → energy + lactic acid. The intensity is so high that the body cannot deliver oxygen fast enough, so glucose is broken down without oxygen. The activity must be short because lactic acid builds up rapidly, causing fatigue.

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Mixed Sports (Both Systems Used)

Most team sports and many individual sports involve both energy systems. The performer switches between aerobic and anaerobic depending on the demands at any given moment.

Sport	Aerobic Component	Anaerobic Component
Football	Jogging between plays, maintaining position (~90 mins)	Sprinting for the ball, jumping for headers, shooting
Rugby	Jogging back into position, sustained play	Sprinting, tackling, scrummaging
Tennis	Moving around the court between rallies (~1–5 hrs)	Explosive serves, sprint to the net, overhead smash
Basketball	Moving around the court, marking opponents	Fast breaks, jump shots, explosive rebounds
Cricket	Fielding (walking/jogging for extended periods)	Bowling (explosive action), batting (explosive shots), sprint between wickets
Hockey	Sustained movement throughout the match (~70 mins)	Short sprints, drag flicks, tackles
Badminton	Rally play, court movement (~30–90 mins)	Explosive smashes, lunges, jump shots
Boxing	Moving around the ring, maintaining guard (~12 rounds)	Explosive combinations, power punches

Exam Tip: When discussing a sport that uses both systems, identify specific actions within the sport and classify each one. For example, in football: "A midfielder jogging back into position is working aerobically because the intensity is low and the duration is sustained. However, when they sprint to win a tackle, they switch to the anaerobic system because the intensity becomes maximal and the action is short-lived."

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Structuring Exam Answers

The IDEA Framework

For any question asking you to apply energy systems to sport, use this framework:

Step	Action	Example (Tennis Serve)
I — Identify	Name the energy system	The tennis serve predominantly uses the anaerobic energy system
D — Duration	State the duration of the action	The serve takes approximately 1–2 seconds
E — Energy equation	State the relevant equation	Glucose → energy + lactic acid
A — Analyse effects	Explain the physiological consequences	Due to the maximal effort, lactic acid is produced; however, as the action is very brief, accumulation is minimal. Between serves, the aerobic system is dominant, allowing partial recovery.

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Worked Exam Question 1 (4 marks)

Question: A 1500 m runner competes in a race. Explain which energy system(s) the runner uses and justify your answer.

Model Answer:

The 1500 m runner predominantly uses the aerobic energy system for the majority of the race because the intensity is moderate and the duration is approximately 3.5–4 minutes, allowing the body to supply sufficient oxygen to the working muscles. The aerobic equation is used: glucose + oxygen → energy + CO2 + water. (2 marks)