Grade by Grade
A–B. Active Living and Movement Competence · Active Living and Movement: Move Well, Train Smart, Stay Safe

Twenty Minutes Strong: Sustained Moderate to Vigorous Activity

A2.1 1.1About 70 minutes
Learning goals
  • I can take part in at least 20 minutes of sustained moderate to vigorous physical activity, to the best of my ability.
  • I can calculate my target heart-rate zones using the heart-rate reserve (Karvonen) method.
  • I can check my intensity with heart rate, the talk test and an effort scale, and adjust to stay in my zone.
  • I can design a 20-minute fitness blast or non-stop game.

Words to know

sustained
Kept going without long stops. Sustained activity lasts for a continuous period, such as 20 minutes.
moderate to vigorous physical activity (MVPA)
Activity that makes you breathe harder and raises your heart rate: moderate (you can talk but not sing) to vigorous (only a few words at a time).
resting heart rate
Your heart rate after sitting or lying quietly for several minutes, often best measured just after waking up.
heart-rate reserve
Estimated maximum heart rate minus resting heart rate: the range your heart can work within.
Karvonen method
A way to find target heart rates using heart-rate reserve: target = (reserve × percent) + resting heart rate.
fitness blast
A short, high-energy aerobic session, often in intervals, that keeps everyone moving.

Remember from Grade 8

In Grade 8 you estimated maximum heart rate as 220 − age and found moderate (about 64% to 76% of maximum) and vigorous (about 77% to 93% of maximum) zones. You also used the talk test, a 0 to 10 effort scale and the 15-second pulse × 4.

In Grade 9 you'll use a more personal method that also uses your resting heart rate, and you'll keep your effort up for at least 20 minutes at a time.

Hook: same age, different hearts

Ava and Ben are both 14. Ava's resting heart rate is 70 beats per minute (bpm). Ben's is 58 bpm, because he has trained for cross-country for two years.

The 220 − age method gives them exactly the same zones. But their hearts aren't the same! A method that includes resting heart rate gives each of them zones that fit their own body better.

What A2.1 asks of you

The curriculum expects you to participate regularly in sustained moderate to vigorous physical activity for at least 20 minutes, to the best of your ability. Examples it gives:

  • Aerobic fitness blasts (intervals of skipping, jumping jacks, dance moves);
  • Capture the flag (lots of running and dodging);
  • Non-stop play in small-sided games (2 v 2 or 3 v 3 so nobody stands around).

"Sustained" means you keep moving. A game where you wait 10 minutes for your turn does not count as 20 minutes of MVPA.

The heart-rate reserve (Karvonen) method

  1. Measure resting heart rate (RHR): sit quietly for 5 minutes (or check right after waking up), count your pulse for 30 seconds and multiply by 2.
  2. Estimate maximum heart rate (MHR): 220 − age.
  3. Find heart-rate reserve (HRR): HRR = MHR − RHR.
  4. Find target heart rate (THR): THR = (HRR × intensity %) + RHR.

A commonly used guideline (from the American College of Sports Medicine) is:

  • Moderate: about 40% to 59% of heart-rate reserve.
  • Vigorous: about 60% to 89% of heart-rate reserve.

These are estimates. Use them together with how you feel.

Worked example

Let's find Ava's zones

Ava is 14 and her resting heart rate is 70 bpm. Find her moderate and vigorous zones with the Karvonen method. Round to whole numbers.

  1. MHR: 220 − 14 = 206 bpm.
  2. HRR: 206 − 70 = 136 bpm.
  3. Moderate: 0.40 × 136 + 70 = 54.4 + 70 = 124.4 → 124; 0.59 × 136 + 70 = 80.24 + 70 = 150.24 → 150.
  4. Vigorous: 0.60 × 136 + 70 = 81.6 + 70 = 151.6 → 152; 0.89 × 136 + 70 = 121.04 + 70 = 191.04 → 191.
  5. Check: all numbers are between her resting rate (70) and her estimated maximum (206), and they go up in order.

Ava's moderate zone is about 124 to 150 bpm and her vigorous zone is about 152 to 191 bpm.

Ava: age 14, resting heart rate 70 beats per minute (bpm)moderate124 to 150vigorous152 to 1916080100120140160180200resting 70max 206heart-rate reserve = 206 − 70 = 136
Ava's zones on a heart-rate scale. The heart-rate reserve is the stretch from her resting rate (70) to her estimated maximum (206). Her moderate zone (124 to 150) and vigorous zone (152 to 191) sit inside it.

Three ways to check intensity

You already know these from Grade 8. Use them together:

  • Heart rate: stop briefly, count for 10 seconds and multiply by 6 (or 15 seconds × 4), then compare with your zones.
  • Talk test: moderate = you can talk but not sing; vigorous = only a few words at a time.
  • Effort scale (0 to 10): moderate is about 5 to 6; vigorous is about 7 to 8.

Heat, stress, caffeine and illness can push heart rate up, so if the numbers and your feelings disagree, trust how you feel and slow down if needed.

moderatevigorous6010014018006162633minutesbpmwarm-upmain part: 20 minutes in the zonescool-down
Ava's heart rate during a fitness blast (a typical pattern, not real data). It climbs during the warm-up, stays in her moderate and vigorous bands for the full 20-minute main part (with short vigorous bursts), then comes down in the cool-down.

Living skill: self-monitoring (1.1)

Checking your intensity during activity is self-monitoring. If you are below your zone, speed up, add arm movements or take bigger steps. If you are above it and struggling, ease off for 30 seconds but keep moving. The goal is 20 minutes of steady effort, not 3 minutes of sprinting followed by 17 minutes of sitting.

Worked example

Let's read Ben's pulse checks

Ben is 14 with a resting heart rate of 58 bpm. His Karvonen zones are moderate about 117 to 145 bpm and vigorous about 147 to 190 bpm. During capture the flag he counts 24 beats in 10 seconds, and later 19 beats in 10 seconds. What zone was he in each time?

  1. Check his zones first: MHR = 206; HRR = 206 − 58 = 148. 0.40 × 148 + 58 = 117.2 → 117; 0.59 × 148 + 58 = 145.32 → 145; 0.60 × 148 + 58 = 146.8 → 147; 0.89 × 148 + 58 = 189.72 → 190.
  2. First count: 24 × 6 = 144 bpm. That's in his moderate zone (117 to 145), near the top.
  3. Second count: 19 × 6 = 114 bpm. That's below moderate. He was probably standing in jail waiting to be freed.
  4. Adjust: when he's free again, he should keep moving (jog, shuffle, make runs) to stay in his zone.

144 bpm: moderate. 114 bpm: below his zone (light). Ben needs to keep moving to make his 20 minutes count.

Hands-on activity

20-minute fitness blast with pulse checks

You need: running shoes, a timer, water, a notebook, a clear space (yard, park or a room about 2 m by 3 m), and a skipping rope (optional).

Before you start: find your resting heart rate (sit for 5 minutes, count for 30 seconds × 2) and calculate your Karvonen zones.

Warm-up (6 min): march, arm circles, side shuffles, gentle squats, then 1 minute of easy jogging on the spot.

Main part (20 min): repeat this 4-minute block 5 times:

  • 1 min skipping (or jog on the spot)
  • 1 min jumping jacks (or step-jacks: step one foot out at a time)
  • 1 min squat to calf raise
  • 30 s fast feet (vigorous burst)
  • 30 s march (keep moving)

Pulse checks: at the end of blocks 1, 3 and 5, count for 10 seconds × 6. Record it, plus your talk test and effort number.

Cool-down (6 min): slow walk, then stretch calves, quadriceps, hamstrings, hips and chest (20 to 30 seconds each).

Reflect: Were all three checks in your zones? Did your three measures agree?

Safety: Stop and tell an adult if you feel chest pain, dizziness, faintness, or unusual shortness of breath. Keep your inhaler nearby if you have asthma. Skip on a flat, non-slip surface.

Just for fun

My heart-rate monitor and I have a great relationship. It tracks every single beat and never skips one... unless it sees me walking toward the stairs.

Your turn

1

How many minutes of sustained MVPA does A2.1 ask for?

2

Write the Karvonen formula for target heart rate.

3

Leo is 15 with a resting heart rate of 64 bpm. Find his heart-rate reserve.

4

Using Leo's HRR of 141, find the low end of his moderate zone (40%).

5

You count 26 beats in 10 seconds. What is your heart rate?

6

Name the three examples of sustained MVPA given in the curriculum.

7

Why doesn't a softball game where you wait 10 minutes to bat count as 20 minutes of sustained MVPA?

More practice: warm-up

1

What is resting heart rate?

2

Estimate the maximum heart rate of a 15-year-old.

3

What percentage range of heart-rate reserve is moderate intensity?

4

In the talk test, what can you do at a moderate intensity?

5

What is a fitness blast?

More practice: on your own

1

Find the full moderate and vigorous zones for Leo (15, resting 64 bpm, HRR 141). Round to whole numbers.

2

Explain why two people of the same age can have different Karvonen zones.

3

Turn a game of tag into non-stop, small-sided MVPA for 4 players.

4

Ben (vigorous zone about 147 to 190) counts 33 beats in 15 seconds. Is he in his vigorous zone?

5

Your heart rate is in your vigorous zone, but it's 32 °C outside and you feel dizzy. What should you do and why?

Challenge

1

Ava (resting 70, MHR 206) wants to train at 75% of her heart-rate reserve. What target heart rate is that? What should her 10-second count be?

2

Compare Ava's vigorous zone using the Grade 8 method (77% to 93% of MHR) with the Karvonen method (152 to 191). Show your work and comment.

3

Over 8 weeks of training, Ben's resting heart rate drops from 58 to 54 bpm. What happens to his heart-rate reserve? What does a lower resting rate often show?

Check your understanding

Quiz

1.

Heart-rate reserve (HRR) equals:

2.

Ava (HRR 136, RHR 70) at 50% intensity has a target heart rate of:

3.

Which activity best meets A2.1?

4.

A count of 25 beats in 10 seconds equals:

5.

Vigorous intensity in the heart-rate reserve guideline is about:

6.

Why does the Karvonen method give more personal zones than 220 − age alone?

For parents and teachers

Big idea: Expectation A2.1 asks students to participate regularly in sustained moderate to vigorous activity for at least 20 minutes. This lesson adds the heart-rate reserve (Karvonen) method to the Grade 8 tools: target = (maximum − resting) × percent + resting.

How to help at home:

  • Help your teen measure resting heart rate in the morning a few days in a row and average it.
  • Join the 20-minute fitness blast and do pulse checks together.
  • The arithmetic connects to Grade 9 math (substituting into a formula, percents).

Common difficulties:

  • Forgetting to add the resting heart rate back at the end of the formula.
  • Using percent of maximum instead of percent of reserve.
  • Treating the zones as exact. They are estimates; how your teen feels matters too.

Safety: If your teen has asthma, a heart condition or another health concern, follow your health-care provider's advice on intensity. Chest pain, fainting or unusual breathlessness means stop and seek medical advice.