Why Does Your Heart Beat Faster When You Run?
- Rachel Lee
- Aug 9
- 5 min read
For children aged 6-10
Written By: Joy Omowunmi Sole
Edited By: Rachel Lee
Have you ever raced with your family or friends, played football, danced to your favourite song, or skipped across the playground?
After a few minutes, you stop to catch your breath, and you place your hand on your chest. Thump! Thump! Thump! Your heart is beating much faster than before!
Have you ever wondered why? Don't worry, your heart isn't in trouble. It's simply doing its amazing job.
Meet Your Amazing Heart
Your heart is one of the hardest-working muscles in your body. It is about the size of your fist and works all day and all night, even while you are asleep! (American Heart Association, 2026).
Think of your heart as a powerful pump. It pumps blood through tiny tubes called blood vessels to every part of your body.
Your blood carries oxygen and nutrients that your muscles, brain, and other organs need to stay healthy and active.
Your lungs are your heart's best teammate. Every time you breathe in, your lungs fill your blood with fresh oxygen, and your heart pumps it around your body.
As you run and play, your muscles use up that oxygen to make energy. Then, the blood then travels back to your lungs to collect fresh oxygen before your heart pumps it around your body again. This amazing teamwork keeps you moving, learning, and having fun (National Heart, Lung, and Blood Institute, 2022).
What Happens When You Start Running?
Imagine you are running to score the winning goal in a football match or running a relay race. Your leg muscles begin working much harder than when you are sitting or walking. Working muscles need more oxygen so they can make energy and keep moving (National Heart, Lung, and Blood Institute, 2022).
Your brain quickly sends a message to your heart: "The muscles need more oxygen, pump faster!"
Your heart responds right away by beating faster. This helps send more oxygen-rich blood to your muscles, giving them the energy they need to keep running, jumping, and playing (KidsHealth, 2023)
Why Do You Breathe Faster, Too?
Have you noticed that you also breathe faster after running? Remember that your heart and lungs work together as a team. Your lungs bring oxygen into your body. Your heart carries that oxygen to your muscles. The harder you exercise, the harder your heart and lungs work together to help you stay active.
Is It Normal for My Heart to Beat Faster?
Yes! A faster heartbeat during exercise is a sign that your heart is doing exactly what it should. When you finish playing and take a short rest, your muscles don't need as much oxygen anymore. Your heart slows down and returns to its normal speed (British Heart Foundation, 2024).
Regular exercise helps keep your heart healthy and strong because your heart is a muscle. Just like the muscles in your arms and legs, it gets stronger when you exercise regularly. Running, jumping, dancing, and playing are all fun ways to help keep your heart healthy and strong.
Did You Know?
❤️ Your heart beats about 100,000 times every day.
❤️ It never takes a holiday, even while you are asleep.
❤️ Your heart is made of a special type of muscle called cardiac muscle. It beats all by itself, so you don't have to think about it!
Isn't your heart amazing?
Become a Heart Detective
Can you discover how your heart changes when you exercise? You can check by checking your pulse. Your pulse is the beat you can feel when your heart pumps blood through your body. When you exercise, your muscles need more oxygen, so your heart beats faster. That is why your pulse becomes faster too.
Let's investigate how your heart works. This simple activity will help you feel your heartbeat before and after exercise.
What You Will Need
A timer or stopwatch
A pencil
A piece of paper
Steps
Sit quietly for two minutes.
Place your index and middle fingers on the inside of your wrist to find your pulse. Do not use your thumb because it has its own pulse.
Count your heartbeat for 30 seconds.
Multiply that number by 2 to find your heartbeats in one minute.
Write the number down.
Now do one minute of jumping jacks, jogging on the spot, or skipping.
Count your pulse again.
Is your heartbeat faster than before?
Rest for three minutes and check your pulse one last time.
What happened? You have just discovered that your heart works harder during exercise!
Remember...
Your heart is an amazing muscle that never stops working.
Every time you run, jump, dance, or play, your heart pumps more oxygen-rich blood to your muscles, giving you the energy to move. So, the next time your heart goes "thump, thump, thump" after playing, you will know exactly why.
Your heart is always working hard to keep you healthy. Every beat helps you learn, play, grow, and explore the world. So, keep moving, keep asking questions, and never stop being curious.
Words to Know
Heart – A strong muscle that pumps blood and oxygen around your body.
Blood – A red liquid that carries oxygen and nutrients to every part of your body.
Blood vessels – Tiny tubes that carry blood to and from your heart and around your body.
Oxygen – A gas in the air that your body needs to make energy.
Lungs – The body parts that help you breathe by adding fresh oxygen to your blood.
Cardiac muscle – The special type of muscle that makes up your heart. It works all day and night to pump blood without getting tired.
Pulse – The beat you can feel when your heart pumps blood through your blood vessels.
Think About It
Can you think of three activities that make your heart beat faster? Try them safely with an adult nearby and compare your pulse after each one.
Works Cited & References:
American Heart Association (2026). About the heart. https://www.heart.org/en/health-topics/congenital-heart-defects/about-congenital-heart-defects/how-the-healthy-heart-works
British Heart Foundation (2024). How your heart works. https://www.bhf.org.uk/informationsupport/how-a-healthy-heart-works
KidsHealth (2023). Your Heart & Circulatory System. Nemours KidsHealth. https://kidshealth.org/en/kids/heart.html
National Heart, Lung, and Blood Institute (2022). How the Heart Works – The Heart. U.S. Department of Health and Human Services. https://www.nhlbi.nih.gov/health/heart
Image Credits: Original illustrations created using ChatGPT and reviewed for educational accuracy by the author.
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