Aerobic Fitness and Heart Rate Zones

Aerobic fitness and heart rate zones

Aerobic means "with oxygen". Aerobic fitness is how well your heart, lungs and blood bring oxygen to your muscles when you run, swim or cycle for a long time. Your heart rate (pulse) is the number of heartbeats in one minute. It is low at rest and rises with effort.

The maximum heart rate is the fastest your heart can safely beat. A quick estimate is 220 − age. It is only an estimate, so a real person can be about 10 beats higher or lower.

We cut the range from 50% to 100% of the maximum into five zones:

• Zone 1, 50–60%: very light, like slow walking.
• Zone 2, 60–70%: light, you can talk easily.
• Zone 3, 70–80%: endurance, you can say short sentences.
• Zone 4, 80–90%: hard, you can say only a few words.
• Zone 5, 90–100%: maximum, you can last only seconds or a short while.

Finding your personal pulse range

Follow three small steps.

1. Find your maximum: 220 − your age. At age 15 this is 205.
2. Find the two ends: multiply by 0.6 and by 0.8. 0.6 × 205 = 123 and 0.8 × 205 = 164.
3. Your range is 123 to 164 beats a minute.

How to count your pulse: Press two fingers (not the thumb) on the inside of your wrist. Count beats for 15 seconds and multiply by 4. Or use a heart-rate monitor or watch.

Your resting heart rate is your pulse when you sit quietly. For fit people it is lower, because a strong heart pushes out more blood in each beat.

Endurance training with pulse control

To build stamina, spend most of your training time in Zones 2 and 3 (60–80%). Here the body burns fuel with oxygen, and the heart and lungs grow stronger without too much strain.

Pulse control means checking your pulse while you train and changing your speed:

• Pulse below your range: speed up a little.
• Pulse inside your range: keep going.
• Pulse above your range: slow down or walk until it drops.

A good session: 5 minutes of warm-up, 20–40 minutes inside your range, and 5 minutes of cool-down. Add a short hard burst (Zone 4) only now and then, with rest after it. Stop and tell an adult if you feel dizzy, have chest pain or cannot breathe well.

Tracking weekly activity versus screen time

Children and teenagers need about 60 minutes of active play or exercise every day, and many health guides suggest keeping free-time screen use to about 2 hours or less. A week table makes your habit visible.

Write the minutes of activity and the hours of screen time for each day. Add up the week and divide by 7 for the average. If your activity average is below 60 minutes, add a short walk, cycling, skipping or a game. If screen time is high, swap one hour for movement. Notice how you feel and sleep, not only the numbers.

Try it: find your own zones

1. Sit quietly for 2 minutes. Count your pulse for 15 seconds and multiply by 4. This is your resting heart rate.
2. Calculate your maximum (220 − age) and your range (60% and 80%). Write them down.
3. Walk fast for 5 minutes and count again. Which zone are you in?
4. In the 3D, move the Age and Effort sliders until the blue marker is inside the blue range.

Key formulas and definitions

• Maximum heart rate ≈ 220 − age
• Lower end of range = 0.6 × maximum
• Upper end of range = 0.8 × maximum
• Beats per minute = beats in 15 s × 4
• % of maximum = pulse ÷ maximum × 100

Worked examples

Common mistakes

• Using 220 − age as an exact number. It is only a guide; real maximums differ by about 10 beats.
• Counting pulse with the thumb. The thumb has its own pulse. Use two fingers.
• Forgetting to multiply: 15-second count × 4, not × 2.
• Thinking harder is always better. Most endurance training should be in Zones 2–3; hard zones need rest after them.