Training Thresholds

To improve fitness, you must exercise at the right intensity. If you train too gently, your body will not adapt; if you train too hard for too long, you risk injury or overtraining. The concept of training thresholds helps performers and coaches identify the correct exercise intensity. This lesson covers the aerobic and anaerobic training thresholds, maximum heart rate, and how to calculate and apply target training zones — all essential content for the Edexcel GCSE PE specification (1PE0 — Topic 2: Physical Training).

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Maximum Heart Rate (MHR)

Before you can work out your training thresholds, you need to know your maximum heart rate (MHR). This is the highest number of times your heart can beat per minute during maximal exercise.

The Formula

$\text{MHR} = 220 - \text{age}$MHR=220−age

Age	MHR (bpm)
14	206
15	205
16	204
20	200
30	190
40	180

Exam Tip: You must memorise this formula. Edexcel questions regularly ask you to calculate MHR for a performer of a given age. Always show your working in calculation questions — you can still earn marks even if your final answer is wrong.

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What Is a Training Threshold?

A training threshold is the minimum intensity (expressed as a percentage of MHR) at which a person must exercise to gain a fitness benefit from that particular energy system. Training below the threshold will not produce significant physiological adaptations in that zone.

There are two main training thresholds:

Threshold	% of MHR	Energy System Trained
Aerobic training threshold	60–80% of MHR	Aerobic system
Anaerobic training threshold	80–90% of MHR	Anaerobic system

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The Aerobic Training Zone (60–80% MHR)

When you exercise at 60–80% of your maximum heart rate, you are working in the aerobic training zone. At this intensity:

• The cardiovascular and respiratory systems can deliver enough oxygen to the working muscles.
• Energy is produced aerobically (with oxygen).
• You develop cardiovascular endurance (also called aerobic fitness or stamina).
• This zone is appropriate for activities such as jogging, steady swimming, cycling at a comfortable pace, and continuous moderate-intensity training.

Calculating the Aerobic Training Zone

For a 16-year-old:

$\text{MHR} = 220 - 16 = 204 \text{ bpm}$MHR=220−16=204 bpm

$\text{Lower limit} = 204 \times 0.60 = 122 \text{ bpm}$Lower limit=204×0.60=122 bpm

$\text{Upper limit} = 204 \times 0.80 = 163 \text{ bpm}$Upper limit=204×0.80=163 bpm

So the aerobic training zone for a 16-year-old is 122–163 bpm.

Exam Tip: Always show every step of the calculation — MHR first, then each boundary. Marks are awarded for the process, not just the final answer.

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The Anaerobic Training Zone (80–90% MHR)

When you exercise at 80–90% of your maximum heart rate, you are working in the anaerobic training zone. At this intensity:

• The cardiovascular system cannot supply oxygen fast enough to meet demand.
• Energy is produced anaerobically (without sufficient oxygen), leading to lactic acid accumulation.
• You develop anaerobic fitness — the ability to work at high intensity for short bursts.
• This zone is appropriate for interval training, sprint training, and high-intensity game play.

Calculating the Anaerobic Training Zone

For a 16-year-old:

$\text{MHR} = 220 - 16 = 204 \text{ bpm}$MHR=220−16=204 bpm

$\text{Lower limit} = 204 \times 0.80 = 163 \text{ bpm}$Lower limit=204×0.80=163 bpm

$\text{Upper limit} = 204 \times 0.90 = 184 \text{ bpm}$Upper limit=204×0.90=184 bpm

So the anaerobic training zone for a 16-year-old is 163–184 bpm.

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The Training Zones Diagram

graph TD
    A["Maximum Heart Rate<br>(MHR = 220 − age)"] --> B["90% MHR"]
    A --> C["80% MHR"]
    A --> D["60% MHR"]
    B --- E["Above 90% MHR<br>Very high intensity — risk of overtraining"]
    C --- F["80–90% MHR<br>ANAEROBIC TRAINING ZONE<br>Develops speed and anaerobic power"]
    D --- G["60–80% MHR<br>AEROBIC TRAINING ZONE<br>Develops cardiovascular endurance"]
    D --- H["Below 60% MHR<br>Below aerobic threshold — limited fitness benefit"]

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Why Training Thresholds Matter

Training thresholds are important because they allow performers and coaches to:

1. Target specific energy systems. A marathon runner needs aerobic endurance and should train primarily in the aerobic zone. A 100 m sprinter needs explosive anaerobic power and should include sessions in the anaerobic zone.
2. Ensure training is effective. Working below the aerobic threshold (below 60% MHR) provides little cardiovascular benefit.
3. Plan training programmes. By combining sessions in both zones, coaches can develop all-round fitness.
4. Monitor intensity. Heart rate monitors allow performers to check in real time whether they are working in the correct zone.

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Applying Training Thresholds to Different Sports

Sport / Activity	Target Zone	Reason
Long-distance runner	Aerobic (60–80% MHR)	Needs sustained cardiovascular endurance
200 m sprinter	Anaerobic (80–90% MHR)	Needs high-intensity power for a short burst
Footballer	Both zones	Aerobic base for 90 minutes of play; anaerobic for sprints, tackles, shots
Cyclist (time trial)	Upper aerobic / lower anaerobic	Works near the threshold between the two zones
Boxer	Both zones	Aerobic fitness for 12 rounds; anaerobic bursts for combinations

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Worked Exam-Style Question

Question: A 15-year-old sprinter wants to train in the anaerobic zone. Calculate the heart rate range they should train in.

Answer:

Step 1 — Calculate MHR:

$\text{MHR} = 220 - 15 = 205 \text{ bpm}$MHR=220−15=205 bpm

Step 2 — Calculate the lower boundary (80% MHR):

$205 \times 0.80 = 164 \text{ bpm}$205×0.80=164 bpm

Step 3 — Calculate the upper boundary (90% MHR):

$205 \times 0.90 = 184.5 \text{ bpm}$205×0.90=184.5 bpm

Answer: The 15-year-old sprinter should train at a heart rate between 164 and 184.5 bpm (or approximately 164–185 bpm).

Exam Tip: In the exam, always round sensibly if you get a decimal — a heart rate of 184.5 bpm would typically be rounded to 185 bpm in practice.

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Monitoring Training Intensity

Performers can monitor their heart rate to check they are training in the correct zone using several methods:

Method	Description	Advantage	Disadvantage
Heart rate monitor (chest strap)	An electronic device worn around the chest that detects electrical signals from the heart	Very accurate; provides real-time continuous data	Can be uncomfortable; costs money
Sports watch / fitness tracker	A wristwatch with an optical heart rate sensor	Convenient and easy to use	Slightly less accurate than a chest strap, especially during high-intensity movement
Manual pulse check (carotid or radial)	The performer counts their pulse for 15 seconds and multiplies by 4	Free; no equipment needed	Must stop exercising to check; less accurate; impractical during intense activity

Using Data to Adjust Training

If a performer checks their heart rate and finds they are below their target zone, they should increase the intensity (e.g., run faster, add resistance). If they find they are above their target zone, they should reduce the intensity to avoid overtraining or injury.

Coaches use training thresholds to design sessions that achieve specific goals:

• Aerobic base sessions: Long, steady runs or swims at 60–80% MHR to build cardiovascular endurance.
• Threshold sessions: Working at the boundary between aerobic and anaerobic zones (~80% MHR) to improve the body's ability to work at higher intensities before lactic acid accumulates.
• Interval training: Alternating between high-intensity bursts in the anaerobic zone and recovery periods in or below the aerobic zone.

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Additional Worked Example

Question: A 20-year-old rower wants to develop cardiovascular endurance. Calculate their aerobic training zone and explain why training in this zone is appropriate. (4 marks)

Answer: