Chapter 1: How Your Body Gets Stronger

Chapter Introduction

Wiggle your fingers.

Now stretch your arms above your head. Now drop them. Now wiggle your fingers again.

That was movement. You did it without thinking. Your body just answered.

Hi. I am the Lion.

We have met before.

If you read my G3 chapter — Moving and Your Body — you and I are already friends. You already know that your body is made to move. You already know that you have muscles, bones, and joints that work together. You already know that moving helps your body, your brain, your sleep, and your feelings. You already know that your body sends you signals while you move, and that you tell a trusted grown-up when something feels off. You already know that every body moves in its own way.

Welcome back. The Lion is glad to see you again.

You are nine or ten years old now. You are bigger than you were at G3. Your body has done a lot of moving since we last talked. Your muscles have practiced. Your bones have grown. You can hold longer chapters in your head. You are ready for the next step.

This chapter has three big ideas, and each one is one step beyond what we talked about at G3.

The first big idea is how your body actually moves. At G3 I told you about muscles, bones, and joints. This time we will add the heart and the lungs — the energy team that powers your movement. And I will introduce you to the four kinds of moves your body can do, named by their job.

The second big idea is how moving makes you stronger. This is where the Lion really wants you to pay attention. At G3 I told you moving makes your body stronger. This time we will go deeper. The Turtle (Coach Brain) taught you in How Your Brain Works that practice strengthens connections in your brain. The Lion adds: practice strengthens your body too — but only if you also rest, eat well, and sleep. That cycle is one of the most important ideas in this whole chapter.

The third big idea is the most important one, like at G3. You listen to your body when you move. Your body has signals — some are normal, some mean stop. You learn the difference. And if something gets really wrong, trusted grown-ups handle it. (At G3 the Lion taught you about 911 for the first time. That is still true at G4. We will say it again.)

Are you ready? Take one deep breath. The Lion is in your corner. Let's go.

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Lesson 1.1: How Your Body Moves

Learning Objectives

By the end of this lesson, you will be able to:

• Describe how muscles, bones, and joints work together (from G3) AND how the heart and lungs join the team
• Name the four kinds of moves your body can do
• Tell what your heart does when you move
• Tell what your lungs do when you move
• Notice the four kinds of moves you used today

Key Terms

The Lion Watches Again

At G3, I told you about your muscles, your bones, and your joints. They work together to make you move. Muscles pull bones at joints. That is the basic move every body makes — when you bend your arm, when you take a step, when you wiggle your fingers.

That is still true at G4. The Lion is not going to take it back. The Lion is going to ADD to it now.

You have two more teammates that join in whenever you move. Without them, your muscles could not work for more than a few seconds. With them, you can run, climb, dance, and play all day.

Those teammates are your heart and your lungs.

Heart and Lungs — The Energy Team

When you move — especially when you move hard — your muscles need fuel. They need oxygen (from the air you breathe) and food (the energy the Bear told you about). All of that gets to your muscles through your blood.

Here is how it works.

Your lungs are two soft parts inside your chest where breathing happens. (The Dolphin told you about lungs in Breath and Your Body at G3.) When you move hard, you breathe faster. Each breath pulls in more oxygen from the air. The oxygen goes from your lungs into your blood [1].

Your heart is a strong muscle inside your chest. It beats — thump, thump, thump — pushing blood through tubes (called blood vessels) to every part of your body. When you move, your heart beats faster, sending blood more quickly to the muscles that are working [2].

Your muscles grab the oxygen and the food from the blood that comes their way, use those to make movement, and then send the used blood back to be refreshed.

So the cycle goes:

• Lungs pull in air
• Air goes into blood
• Heart pumps blood
• Blood reaches muscles
• Muscles use what they get to move
• Used blood goes back to heart and lungs to get refreshed
• Cycle repeats — many, many times per minute

Right now, while you are sitting and reading, your heart is beating about once per second. Your lungs are breathing about twelve to twenty times a minute. Slow. Steady. Just enough to keep your sitting body going [3].

But the second you stand up and start running, all three teammates pick up the pace at the same time. Your heart beats faster. Your lungs work harder. Your muscles get more fuel. The whole team speeds up together. And the second you stop and rest, they all slow back down together.

The Lion thinks this is one of the most amazing things about being a body. You do not have to tell your heart or lungs to speed up. They do it on their own. Bodies are smart.

Four Kinds of Moves

At G3, I gave you a list of many kinds of moves — running, jumping, climbing, swimming, dancing, throwing, catching, and many more. All of that is still true.

At G4, I am going to organize those moves into four kinds based on what they do for your body. Knowing these four helps you understand what each kind of move actually builds. Most kids do a mix of all four every day without thinking about it.

1. Heart-and-lung moves.

These moves make your heart and lungs work harder than normal. Your heart speeds up. Your breath speeds up. You get a little warm. You might get a little sweaty.

Examples: running, biking, swimming, dancing, walking fast, playing tag, climbing stairs, jumping rope, hiking, scootering on a longer trip, sports like soccer or basketball.

What they build: endurance — the ability to keep going for longer. Kids who do heart-and-lung moves regularly find that they can run farther, bike longer, and not get out of breath as fast [4].

2. Muscle-power moves.

These moves make your muscles work hard against something — gravity, an object, your own body weight, or a hill.

Examples: climbing (trees, monkey bars, climbing walls), lifting things (carrying groceries, helping move boxes), pushing (a swing for a younger sibling, a wagon), pulling (yourself up, a rope), jumping (especially up onto things), doing pushups or pull-ups, gymnastics moves.

What they build: strength — the power of your muscles. Kids who do muscle-power moves regularly find that they can lift more, climb higher, and feel more confident in their bodies [5].

3. Stretching moves.

These moves lengthen your muscles and bend your joints in different ways.

Examples: yoga, reaching as high as you can, bending forward to touch your toes, the stretching that comes before or after sports, dance stretches, slow gentle bends.

What they build: flexibility — how easily your muscles and joints move through their full range. Flexible kids can reach, bend, twist, and recover from awkward positions more easily.

4. Balance moves.

These moves help your body stay steady — not tip over, not lose where you are.

Examples: standing on one foot, gymnastics, dance balance moves, skateboarding, scootering, walking on a beam, riding a bike, even just standing still in a moving bus.

What they build: balance — the ability to stay steady. Balance is part of almost every move you do; you just do not notice it most of the time. Kids who practice balance fall less, hurt themselves less, and move more confidently.

All Four Kinds Together

The Lion has a small rule about the four kinds.

The four kinds work TOGETHER to build a strong, capable body.

A kid who only ever runs (lots of heart-and-lung moves) might end up with stiff legs and weaker arms. A kid who only ever lifts heavy things (muscle-power moves) might be strong but slow. A kid who only ever stretches might be flexible but not very strong. A kid who only ever does balance might never build the endurance to keep up with their friends in a long game.

Variety — doing some of all four kinds — is what builds the whole body.

Most kids your age do this naturally without thinking. Recess has running and climbing. PE has different sports. Walking to school is endurance. Carrying a backpack is strength. Stretching when you wake up is flexibility. Riding a bike is balance. You are already doing all four kinds most weeks. The Lion just wants you to see them.

Every Body Has Its Own Way

The Lion said this at G3 and is saying it again at G4 because it matters even more as you get older.

Every body has its own way to move. All four kinds of moves are for every body.

Kids who use wheelchairs do all four kinds: pushing their wheels is heart-and-lung + muscle-power; stretching from a chair is stretching; wheelchair sports build balance. Kids with asthma do all four kinds — at their own pace, with help from their grown-ups and doctors. Kids with bigger bodies, smaller bodies, in-between bodies all do all four kinds — in their own way, at their own pace. Kids learning new skills — running for the first time, climbing for the first time, swimming for the first time — do all four kinds slowly and beautifully.

The Lion never compares one kid's moves to another's. What matters is that you are moving — in your own way, at your own pace, with the people who care about you.

Notice Your Four Kinds Today

Here is something the Lion wants you to try.

Pick today. Think back over what you did. Try to find at least one move you did in each of the four kinds:

• One heart-and-lung move
• One muscle-power move
• One stretching move
• One balance move

You may have to think for a moment. Walking to a bus stop is heart-and-lung. Picking up your backpack is muscle-power. Reaching for something high on a shelf is stretching. Standing on one foot to pull off a sock is balance.

Did you find all four? The Lion is willing to bet you did.

Most kids do all four every day without realizing it. Now you can see them.

Lesson Check

1. What is the "energy team" that joins your muscles when you move?
2. Why does your heart beat faster when you run?
3. Name the four kinds of moves the Lion introduced. Give one example of each.
4. Why does the Lion say variety matters — doing some of all four kinds?
5. Find one move from each of the four kinds that you did today.

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Lesson 1.2: How Moving Makes You Stronger

Learning Objectives

By the end of this lesson, you will be able to:

• Tell that practice strengthens your body (parallel to how practice strengthens your brain)
• Explain why muscles get stronger DURING REST, not during the move itself
• Describe the stronger-getting cycle (move, rest, food, sleep, repeat)
• Name seven things that help your body get stronger
• Notice one part of your body that has gotten stronger in the last year

Key Terms

A Lion Story

The Lion was a cub once. (A long time ago. The Lion remembers it well.)

When the Lion was a cub, the Lion was small. Weak compared to the big lions. Could not run as fast. Could not jump as high. Could not catch what the big lions caught. The Lion watched the older lions and wanted to do what they could do.

So the Lion played. The Lion ran with other cubs. The Lion climbed. The Lion wrestled. The Lion practiced. And then the Lion rested. And ate. And slept. And the next day, played again.

A year passed. The Lion grew. Two years. Three. By the time the Lion was full-grown, the Lion could do everything the older lions could do — and some things even better.

Why? Because the Lion practiced, rested, ate, and slept — over and over, for years.

Your body works the same way.

This is the big G4 idea of this chapter. The Lion has waited until now to tell you because you are old enough.

Practice Strengthens the Body

The Turtle taught you something important at G4 in How Your Brain Works. The Turtle said:

When you practice something, your brain builds connections between its parts. Each time you repeat, the connections get a little stronger. Practice strengthens connections.

That is true for your brain. The Lion has a parallel truth for your body.

When you practice a movement, your body gets a tiny bit stronger over time — IF you also rest, eat well, and sleep. Practice strengthens the body too.

Think about something you can do now that you could not do a year ago. Run farther? Climb higher? Jump rope without tripping? Swim across the pool? Do a cartwheel? Stand on your head?

You did not get better at it by trying once. You got better by trying many times, over many days or weeks or months. Practice + rest = your body building new ability.

The Lion is going to tell you something most kids do not know. Muscles do not get stronger during the move itself. They get stronger DURING REST, after the move is done.

The Stronger-Getting Cycle

Here is how the body's stronger-getting cycle actually works.

Step 1 — You do a movement that challenges your body. Maybe a long run. Maybe a hard climb. Maybe ten pushups. Maybe a full jump-rope session. Maybe a tough soccer practice.

Step 2 — Your body is a little tired afterward. Maybe your muscles ache a tiny bit. Maybe your breath is short. Maybe you want a snack and a sit. That tiredness is your body saying: "I worked. Now I need to rebuild." [5]

Step 3 — With rest, food, and sleep, your body rebuilds itself a tiny bit stronger than it was before. This part is invisible. It happens while you are not even paying attention. You sit. You eat dinner. You sleep through the night. While all that is happening, your body is doing repair-and-rebuild work [6]:

• Muscles rebuild themselves slightly stronger, using protein from your food.
• Bones get a tiny bit denser if you put weight on them (jumping, lifting, weight-bearing moves help bones grow strong) [7].
• Heart and lungs get a tiny bit better at their job if you challenged them.

Step 4 — Repeat. A few days later, you do another challenging move. Now your body is a tiny bit stronger than it was last time. You can go a little farther, lift a little more, jump a little higher.

Step 5 — Over weeks and months, the tiny bits add up to real strength.

This is true for kids your age. This is true for grown-ups. This is true for the Lion. This is true for every athlete in the world. Strong bodies are built one tiny bit at a time, with rest in between.

The Bear, the Turtle, the Cat, and the Lion Agree

The Lion has a moment now to talk about teamwork.

You met the Bear (Coach Food) at G3 and again at G4. The Bear taught you that food becomes you — that the things you eat get used to build the parts of your body. Protein especially helps muscles. Bones use minerals. Brains use healthy fats.

You met the Turtle (Coach Brain) at G3 and again at G4. The Turtle taught you that practice strengthens connections in your brain.

You met the Cat (Coach Sleep) at G3 and again at G4. The Cat taught you that sleep is when your body does its biggest work — growth, repair, and rebuilding all happen during deep sleep at night.

The Lion is adding: all of that work pays off in your body when you move regularly.

Movement + food + sleep + rest = real strength.

This is the equation. No supplement, no shortcut, no protein powder for a kid your age does this better than the four basics — move, eat, sleep, rest. The Bear, the Turtle, the Cat, and the Lion all agree on this.

Why "Rest Days" Are Real

Here is something the Lion wants you to know that surprises some kids.

Real athletes have rest days. Days when they do not do the same hard practice they did the day before. Maybe they do a gentle walk. Maybe they stretch. Maybe they do nothing physical. Sometimes they take a whole day off.

This is not laziness. This is part of getting stronger. Rest days are when the rebuilding finishes. A body that practices the same hard thing every single day with no rest cannot keep rebuilding. The body gets tired in a bad way. Sometimes it gets hurt.

This does not mean you should not move every day. Some moving every day is great — and that is what the AAP and WHO (the big groups of doctors who study kids' health) say most kids do best with [4, 8]. But the hard practice — the part where you really push yourself — works best with rest in between.

If you are a kid your age, you usually do not have to plan rest days carefully. Most kids' schedules naturally have variety — different activities on different days. But if you find yourself practicing the same hard thing over and over with no rest and you feel tired in a bad way — that is a signal to take a rest day.

The Lion is firm about this. Rest is part of strength. Always.

Seven Things That Help Your Body Get Stronger

At G3, I told you four things that help kids move well. Those four are still true. I am going to repeat them and add three more for G4.

The four from G3:

1. Some moving every day. Even a little. About 60 minutes a day across all your activities is what most kid health groups say is good — but this is a range, not a rule. Some kids do less on busy days; some do much more on weekends. What matters is that moving happens regularly [4, 8].

2. A mix of kinds of moves. Variety builds the whole body. (G4 added structure to this — the four kinds: heart-and-lung, muscle-power, stretching, balance.)

3. Time outside when you can. Outside has space, fresh air, sunlight (the Rooster will agree), and more interesting challenges than inside.

4. Moving you enjoy. The moves you like are the moves you will keep doing. Find your favorites.

The three G4 additions:

1. A variety of the four kinds, intentionally. Notice if you have been doing only one or two kinds and try to add the others. Most kids do better with all four mixed across the week.

2. Rest days for harder practice. When you push hard, give your body a day or two to rebuild. This is real. The Lion is firm.

3. Real food (especially protein) and good sleep. The Bear and the Cat agree. You cannot build a strong body without the materials and the rebuilding time. Food + sleep + movement + rest = the four corners of strong.

These seven are not a checklist you have to hit perfectly. They are general practices that help most kids. Your family decides specifics. The Lion is just telling you what helps.

A Movement You Can Practice This Week

Here is what the Lion wants you to try.

Pick one movement skill you would like to get a little better at. Something small. Examples:

• A few more jumping jacks in a row
• Catching a ball with one hand
• Riding your bike without your feet down
• A new dance move
• A specific stretch (touching your toes)
• A specific balance (one-foot standing for longer)
• A specific climbing move on the playground

Practice it for 5 to 10 minutes on three or four days this week. Take a day or two off in between practice days. Eat your meals normally. Get your usual sleep.

By the end of the week, see if you can do the skill a little better than you could on Day 1.

The Lion bets you can. This is the stronger-getting cycle. Practice + rest + food + sleep = real strength. The Lion has watched this happen with kids forever.

Lesson Check

1. The Turtle says practice strengthens brain connections. What does the Lion add about practice and your body?
2. When do muscles actually get stronger — during the move or during the rest?
3. Name the four steps of the stronger-getting cycle.
4. Name three of the seven things that help your body get stronger.
5. The Lion says, "Rest is part of strength." What does that mean?

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Lesson 1.3: Listening to Your Body When You Move

Learning Objectives

By the end of this lesson, you will be able to:

• Tell the difference between normal moving signals and stop signals
• Use the concept of pacing in a long activity
• Recognize feelings about movement (frustration, embarrassment, joy) as normal
• Know what to do if a worry about movement or your body comes up
• Know what to do in a movement emergency

Key Terms

The Lion Is Going to Be Honest

The Lion is going to be honest with you, like the Lion was at G3 and even more clearly at G4.

When you move, your body talks to you constantly. Heart beating fast. Breath getting deeper. Skin warming up. Sweat starting. Muscles working. Some of those signals are normal. They mean your body is doing its job.

Other signals are different. Some signals mean stop. Sharp pain. Can't breathe even after stopping. Feeling dizzy. Hit your head hard. Feeling sick.

At G3 I called these "good tired" and "hurt tired." That is still true at G4. The Lion is going to say more about both now.

Normal Moving Signals

When you move — especially when you move hard — these things are NORMAL. They are not signs to stop. They are signs your body is working.

• Heart beating fast. Right. The Lion just told you in Lesson 1 — your heart speeds up when you move so it can deliver more blood to your muscles. A fast heart during movement is your body doing its job [3].
• Breath getting deeper and faster. Right. Same reason. Your lungs work harder to pull in more oxygen for your muscles. Deep, faster breath during movement is normal [9].
• Sweating. Right. The Camel (Coach Hot) told you about this at G3 — sweat is your body's way of cooling itself. When you move, you make heat, and sweat helps that heat leave. Some kids sweat a lot; some kids barely sweat. Both are normal.
• Getting warm. Right. Same reason. Muscles working = body warming up. The warmth is okay.
• Getting tired (in a good way). Right. This is the "good tired" from G3. Your body did real work. Your muscles are saying, "I need a minute." That is part of the stronger-getting cycle. Good tired goes away after rest. It feels almost satisfying.
• Muscles being a little sore the next day. Sometimes — especially after harder movement, or trying a new move — your muscles are a little sore the next day. This is normal. The Lion calls this "the rebuilding feeling." If it is mild and goes away in a day or two, it is part of getting stronger [5].

The Lion wants you to know all of these because some kids worry when their heart races during running. Or feel weird about sweating. Or think soreness means something is broken. None of those are problems. Your body is working.

Stop Signals

These are different. These are signs to STOP and tell a trusted grown-up.

• Sharp pain that does not go away. A sudden sharp pain — in a joint, in a muscle, in a bone — is different from the gentle soreness of good tired. Sharp pain is a stop signal [10].
• Can't catch your breath, even after stopping. When you stop moving, your breath should slow down within a minute or two. If you still cannot catch your breath after stopping, that is a stop signal. The Dolphin (Coach Breath) told you about this at G3.
• Dizzy or lightheaded. Like the room is spinning or you feel like you might fall. Tell a grown-up.
• Sick to your stomach. Feeling like you might throw up during or right after moving. Tell a grown-up.
• Hit your head hard. Any time you hit your head hard — falling off a bike, falling off a climbing structure, getting hit during a game — tell a grown-up immediately. Even if you feel fine. Some head hits do not show signs for hours [11].
• Skin turning very pale, very red, or very blue. Skin colors that look very different from your usual skin tone in unusual ways during or after moving are stop signals.
• A pop, crack, or sudden weakness. Any of these from a joint or bone during movement is a stop signal. Tell a grown-up.
• Big body pain that does not go away. Mild soreness is normal. Big, lasting pain is a stop signal.

If any of these happen — stop moving, tell a trusted grown-up right away.

In a real emergency — a serious injury, someone is not responding, someone is bleeding badly, someone hit their head hard and is acting confused — a trusted grown-up can call 911. That is the phone number for medical emergencies in the United States. You learned this at G3 Move. It is still true at G4. Kids do not call 911 themselves except in special situations a grown-up has taught you about. You tell a grown-up; the grown-up calls.

Pacing — A New G4 Idea

The Lion has a new idea for you at G4. It is called pacing.

Pacing means: slowing yourself down at the start of a long activity so you do not run out of energy too soon.

Here is the example. You and a friend are going on a long bike ride — maybe a few miles. You feel great at the start. You want to go fast. So you sprint at full speed.

What happens? You run out of energy after the first mile. Now you are tired, and you still have a long way to go.

A different kid takes the same ride. They feel great at the start too. But they pace themselves. They ride at maybe two-thirds of their full speed. They breathe steadily. They feel good. By the time the first kid is wiped out, the pacing kid is still going. And by the end of the ride, the pacing kid arrives with energy left over.

Pacing is one of the most useful skills a kid can learn for movement. It applies to long bike rides, long swims, long runs, long hikes, long games, even long days of activity.

Pacing tips:

• At the start of a long activity, ask yourself: "Can I keep this up for the whole thing?" If not, slow down a little.
• Listen to your breath. If you cannot say a few words while moving, you are going too hard for a long activity.
• Drink water along the way (the Elephant told you about water).
• Eat a snack if it is a really long activity (the Bear told you about food).
• Take small breaks before you absolutely have to.

The Lion thinks of pacing as the wise version of moving. Anyone can sprint. Smart movers pace.

Bodies Are All Different

The Lion said this at G3 and is saying it again at G4 because some things bear repeating.

Every body is different. Every body has its own pace, its own strength, its own moves. Some kids run faster. Some kids are stronger. Some kids are more flexible. Some kids have better balance. Some kids learn new moves quickly. Some kids take longer.

None of these differences make a kid better or worse than any other kid. They make every kid different. The Lion has never compared one kid's moves to another's and never will.

If your friend can do something you cannot, that is just biology. Your body has its own things it is good at. Practice for what matters to you. Be kind about what others are still building.

Feelings About Movement

The Lion has to talk about something important. The Turtle (Coach Brain) talked about feelings at G3 and again at G4 in How Your Brain Works. The Lion has feelings to add specifically about movement.

Sometimes kids your age start having harder feelings about their bodies and how they move. Some examples:

• Embarrassment about being slower than other kids
• Frustration when a skill is taking forever to learn
• Sadness when a body part hurts or does not work the way you want
• Worry about how your body looks during movement (in PE class, at the pool, in a swimsuit, in front of friends)
• Comparison feelings — looking at other kids' bodies and feeling bad about your own
• Pressure from coaches, parents, or peers to do more than feels right
• Seeing things online or on TV about "perfect" bodies and feeling not enough

The Lion wants you to hear this clearly. All of these feelings are normal. None of them mean anything is wrong with you. AND all of them are worth telling a trusted grown-up about.

Especially this one: if you are looking at your body and feeling bad about how it looks — for any reason, from any source — tell a trusted grown-up. The Bear and I agreed on this at G3 and we still agree at G4. Movement is for FEELING good, for what your body can DO, for the joy of it. Movement is NEVER for changing how your body looks.

Kids your age — 9, 10, 11 — sometimes start hearing more about bodies, weight, and shape from social media, friends, family, and TV. Some of what they hear is harmful. If anything you hear or see about your body makes you feel bad, or makes you want to eat less, or makes you want to exercise to change your shape — tell a trusted grown-up right away. That is exactly what the Bear told you about food worries at G4. The Lion agrees one hundred percent.

When to Tell a Trusted Grown-Up

The Lion has the same kind of list every Coach has by now. If any of these things are happening, tell a trusted grown-up.

• Sharp pain or any of the stop signals (Lesson 3 first section)
• A movement worry that keeps coming back
• Feeling embarrassed about how you move, in a way that makes you avoid moving
• Feeling bad about how your body looks during or after movement
• Wanting to exercise more to change how your body looks
• Eating less because you want to look different
• A friend or sibling showing any of these worries
• Anything that just feels wrong

You do not have to be sure. You do not have to figure it out yourself. If something feels wrong, tell a grown-up. That is your part. The grown-up handles the rest.

When a Feeling Feels Really Scary or Unsafe

The Lion is going to say this clearly, like every other Coach has said it.

Sometimes a feeling can get really big. Maybe a feeling about your body or your movement makes you really sad. Maybe a feeling makes you want to skip meals, or do too much exercise, or hurt your body somehow. Maybe a feeling makes you not want to be here.

If a feeling like that ever comes up — tell a trusted grown-up right away. Not later. Right then. The grown-up will not be mad. The grown-up will be glad you told them.

If you cannot reach a trusted grown-up at that moment, here are special phone numbers grown-ups can use when feelings get really scary or unsafe. The Lion wants you to know they exist. You do not have to remember the numbers — the grown-ups in your life can use them.

• For a movement emergency — when someone is badly hurt or unresponsive: a grown-up can call 911 for fast help. (You learned this at G3 Move. It is still true.)
• 988 Suicide and Crisis Lifeline: a grown-up can call or text 988, any time of day or night. Real people answer.
• Crisis Text Line: a grown-up can text HOME to 741741, any time of day or night. Real people answer by text.
• SAMHSA National Helpline: 1-800-662-4357, day or night, for any kind of big worry.
• National Alliance for Eating Disorders: 866-662-1235, weekdays. The Bear told you about this one at G4. It is for grown-ups when worries are about food, eating, or how a kid feels about their body. The Lion adds: especially relevant when movement and body image start mixing in a worrying way.

These helpers are for grown-ups to use when you and they need them. Kids your age do not call helplines on their own. You tell a trusted grown-up first. The grown-up takes care of the rest.

The Bear, the Turtle, the Cat, and the Lion are all saying the same thing. We agree. You are part of a team. You are not alone with movement worries, body worries, or feelings worries. Not now, not ever.

Move for the Joy of It

The Lion will end this chapter with the same thought the Lion ended G3 Move with, because it has not changed and it never will.

Move for the joy of it.

Not for how you look. Not because someone is making you. Not to fit some idea of what a kid your age should be. Move because your body wants to move. Move because it feels good. Move because the world is full of fun things to do.

Run because running feels alive. Climb because the view from up there is wonderful. Dance because the music asks you to. Stretch because your body feels long and good when you do. Balance because finding the center is satisfying. Play because play is one of the best things humans do.

The Lion will see you again at Grade 5. There is more to learn then. For now, this is enough.

The Lion is in your corner. Always.

Lesson Check

1. Name three normal moving signals. Why does the Lion say they are okay?
2. Name three stop signals. What should you do if you notice one?
3. What is pacing? Why does it help in long activities?
4. The Lion says movement is for what your body can do, not for how it looks. What does that mean to you?
5. If a feeling about your body or your movement ever feels really scary, what should you do?

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End-of-Chapter Activity: A Week of Strength

The Lion has one activity for you. It takes one week. You can start any day.

What You Need

• A piece of paper or notebook
• A pencil
• One small movement skill you want to get better at
• A trusted grown-up to share with at the end

What You Do

Step 1 — Pick your skill (Day 1). Choose one small movement skill. It must be safe enough to practice on your own with a grown-up nearby. Examples:

• Jumping rope for longer without missing
• Throwing a ball into a target
• Riding your bike without your feet touching the ground at stops
• A specific dance move
• Touching your toes
• Standing on one foot for longer
• A specific yoga pose
• Catching a ball with one hand

Write the skill at the top of your paper: My movement skill this week: ______.

Step 2 — Track your week. Set up a small chart with seven rows (one per day) and three columns:

• Did I practice today? (Yes / No / Rest)
• About how many minutes?
• How did my body feel?

Step 3 — Practice 4-5 days this week, with 1-2 rest days. Mark practice days and rest days both. Rest days are NOT failure — they are part of the stronger-getting cycle.

For each practice day, spend about 5-10 minutes on the skill. Quality matters more than quantity. Pay attention. Try with your full attention. Notice what is working and what is not.

Step 4 — Notice the four kinds of moves you did. At the end of each day, note which of the four kinds of moves you did that day:

• Heart-and-lung moves?
• Muscle-power moves?
• Stretching moves?
• Balance moves?

You will probably do at least 2-3 of the four kinds most days. Notice patterns.

Step 5 — End-of-week reflection. At the end of the week, write a short paragraph (3-5 sentences) about what you noticed:

• Did the skill get easier across the week?
• Did your body feel different on practice days vs rest days?
• What was the hardest moment? The breakthrough moment?
• Which of the four kinds of moves did you do the most? The least?
• Will you keep practicing this skill or pick a new one?

Step 6 — Share with a trusted grown-up. Show your tracker to a trusted grown-up. Tell them what you noticed. Ask them: Is there a movement skill you are working on? Listen to their answer. Grown-ups practice too.

Step 7 — Keep your paper. Save it. The Lion thinks movement weeks are interesting to look back on. Some kids start a notebook of weekly movement practices and watch their bodies get stronger over time.

What You Will Get From This

You will see — with your own body — the stronger-getting cycle in action. You will feel rest days mattering (or your body will tell you they did). You will start to notice the four kinds of moves you do every day. And you will share something small with a grown-up who loves you.

That is a small habit. It is also a big skill. The Lion thinks both are true.

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Vocabulary Review

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Chapter Review

These questions are not a test. They are a way to check what you remember. Take your time. Look back at the lessons if you need to. There are no tricks.

1. Name the "energy team" that joins your muscles whenever you move.

2. Name the four kinds of moves the Lion introduced. Give one example of each.

3. The Turtle said practice strengthens connections in your brain. What does the Lion add for your body?

4. Name the four steps of the stronger-getting cycle.

5. Name two normal moving signals and two stop signals.

6. If a feeling about your body or your movement ever feels really scary or unsafe, what should you do?

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Instructor's Guide

This guide is for parents, caregivers, teachers, and other grown-ups using this chapter with a child in Grade 4 (ages 9-10).

What This Chapter Teaches

This chapter is the second chapter in Coach Move (the Lion)'s K-12 spiral and the fourth chapter of the Grade 4 cycle. It builds on the Grade 3 chapter Moving and Your Body and connects strongly with the just-shipped G4 Brain (How Your Brain Works) and G4 Sleep (How Sleep Works) chapters. The chapter teaches three big ideas at age-appropriate Grade 4 depth:

1. How your body moves. Builds on G3's muscles/bones/joints by adding the heart and lungs as the energy team for movement. The cardiovascular concept is introduced functionally (heart pumps blood, lungs pull in air, muscles use what they get) without naming the cardiovascular system technically or doing heart-rate math. The chapter introduces four kinds of moves named by job: heart-and-lung moves (cardio), muscle-power moves (strength), stretching moves (flexibility), and balance moves (balance) — without aerobic/anaerobic/VO2max technical naming. Inclusion is load-bearing: kids who use wheelchairs and other mobility supports are explicitly named in all four kinds.

2. How moving makes you stronger. This is the chapter's central G4 insight, designed as a parallel to the Turtle's "practice strengthens connections" at G4 Brain. Practice strengthens the body — but only with rest, food, and sleep. Muscles get stronger DURING REST, not during the move itself. The stronger-getting cycle is taught explicitly: move → rest → eat → sleep → repeat = real strength over weeks and months. Cross-references G4 Food (Bear: food becomes you, protein helps muscles), G4 Brain (Turtle: practice strengthens connections), and G4 Sleep (Cat: deep sleep is when body work happens). Seven things that help the body get stronger are named — G3's four plus three G4 additions (variety of the four kinds, rest days, real food and sleep).

3. Listening to your body when you move. Carries forward G3's framework with G4 deepening: normal moving signals (heart beating fast, breath deeper, sweating, warming up, good tired, mild next-day soreness) are explicitly named as okay — these are not stop signals. Stop signals (sharp pain, can't catch breath, dizzy, sick to stomach, hit your head, skin color changes, pop/crack/sudden weakness) trigger tell-a-grown-up-right-away framing. Pacing is introduced as a new G4 concept. Body-image vigilance is heightened from G3 because ages 9-10 are entering the developmental window where social-media body content reaches kids more strongly — the chapter explicitly addresses movement-and-body-image worries and routes to trusted grown-ups. 911 framing (introduced at G3 Move for the first time in the curriculum) carries forward.

What This Chapter Does NOT Teach

This chapter is intentionally light on content that becomes appropriate at later grades:

• No bone or muscle counts. ~206 bones, ~600 muscles, and Wolff's Law arrive at Grade 6.
• No heart-rate math. Resting and exercise heart-rate calculations, target heart rate zones — all Grade 6+.
• No aerobic/anaerobic technical naming. Grade 6 introduces these as concepts.
• No VO2max, no training periodization, no sport-specific applications. Higher tier territory.
• No body composition, weight, BMI, or appearance-focused framing. All firewalled at G4. Movement is consistently framed for capability, feeling, and joy.
• No specific training protocols. AAP/WHO 60-minutes-per-day consensus is presented as a range, not a rule. Specific exercise prescriptions wait for Grade 9+ at the earliest, and even there are framed as descriptive research.

If your child asks questions in these areas, the best answer is: "That is a great question. Let's figure it out together." Then you, the trusted grown-up, decide what to share.

How to Support the Child

A few things you can do that align with the chapter's framing:

• Celebrate variety, not specialization. Children at ages 9-10 are at an ideal age to try many different kinds of movement. The four-kinds framework helps parents support balanced physical development without specializing too early.
• Model rest as part of strength. When you are visibly recovering — saying "I'm taking a rest day" or "I slept poorly so I'm doing a gentle walk" — your child sees that rest is part of how adults stay strong.
• Never use body shape or weight as motivation for movement. Children at this age absorb adult framing. "Let's go for a walk because it feels good" is healthy. "Let's exercise to burn off that cake" is not. The Lion's framing throughout the chapter avoids this; please reinforce it.
• Watch for the body-image entry points. Ages 9-10 are when social media, peer comments, and family-table comments start landing as body-image messages. If your child says something self-critical about their body, take it seriously — listen first, then gently affirm that all bodies are different and that movement is for feeling good.
• Take stop signals seriously. Children sometimes minimize injuries, especially in front of teammates or coaches. The chapter teaches them to tell you about stop signals; reinforce that you will listen without dismissing.
• Be the safe adult for movement worries. The chapter explicitly tells your child to come to you. Make sure they know you are listening.

Watching for Warning Signs

Children at ages 9-10 are entering the developmental window where movement-and-body-image issues can begin emerging. The chapter is preventive. If you notice any of the following, please contact your pediatrician or a qualified clinician:

• Sudden new restriction of food categories
• Exercise that seems compulsive, secret, or punishing
• Negative body talk in connection with movement ("I have to run today because I ate so much")
• Avoidance of activities that show the body (swimming, PE, sleepovers)
• Comments comparing their body to peers or media images
• Sleep changes alongside movement changes (cross-ref G4 Sleep)
• Mood changes alongside movement changes (cross-ref G4 Brain)
• Any mention of wanting to hurt themselves, hate for their body, or not wanting to be here — these require immediate response

Verified resources (May 2026):

• 911: for any acute medical emergency, including serious injuries during movement.
• 988 Suicide and Crisis Lifeline: call or text 988, 24/7. The right first call for any mention of suicide or self-harm.
• Crisis Text Line: text HOME to 741741, 24/7.
• SAMHSA National Helpline: 1-800-662-4357, 24/7. General mental health and substance use referrals.
• National Alliance for Eating Disorders: 866-662-1235, weekdays. Licensed therapists. Particularly relevant if movement-and-body-image worries appear together.
• Your pediatrician is the best starting place for any persistent concern. For sport-related injuries, a pediatric sports medicine clinician.

Note: the NEDA helpline (1-800-931-2237) is not functional as of this writing. Use the National Alliance for Eating Disorders number above instead.

Pacing

If you are using this chapter in a classroom:

If you are using this chapter at home, two lessons per week is comfortable. The end-of-chapter activity is a one-week project. Lesson 3 may benefit from being read alongside a trusted grown-up — both because the body-image content matters at this age and because it explicitly invites a family conversation about movement and feelings.

Lesson Check Answers

Lesson 1.1:

1. The heart and the lungs. (Together they deliver oxygen and food to muscles through the blood.) 2. Because moving muscles need more blood — more oxygen, more food — so the heart pumps faster to deliver it. 3. Heart-and-lung moves (running, biking, swimming, dancing), muscle-power moves (climbing, lifting, pushing, jumping), stretching moves (yoga, reaching, bending), balance moves (one-foot standing, gymnastics, skateboarding). 4. Because each kind builds a different part of the body. A kid who only runs may have stiff arms; a kid who only lifts may be slow. Variety builds the whole body. 5. Child's own answer.

Lesson 1.2:

1. The Lion says practice strengthens the body too — but only with rest, food, and sleep. Same principle as the brain, different domain. 2. During rest. (Muscles rebuild themselves slightly stronger during the rest after a hard move, not during the move itself.) 3. (1) Practice a move that challenges the body; (2) rest and eat; (3) sleep — body rebuilds; (4) a little stronger — repeat. 4. Any three of: some moving every day, variety of the four kinds, time outside, moving you enjoy, intentional variety, rest days, real food + sleep. 5. That rest is not the opposite of getting stronger — it is part of how getting stronger happens. Your body does its rebuilding work during rest.

Lesson 1.3:

1. Any three of: heart beating fast, breath deeper and faster, sweating, getting warm, good tired, mild next-day soreness. They are okay because they are signs your body is working — doing exactly what it should be doing. 2. Any three of: sharp pain, can't catch breath even after stopping, dizzy, sick to stomach, hit your head hard, skin color changes, pop/crack/sudden weakness, big pain that doesn't go away. Stop moving and tell a trusted grown-up right away. 3. Pacing means slowing yourself down at the start of a long activity so you do not run out of energy too soon. It helps because energy is limited — using it all up early leaves you exhausted with more to do. 4. Child's own thinking. Common answers: movement is for feeling good, for capability, for joy, never for changing body appearance. 5. Tell a trusted grown-up right away. The grown-up can use the National Alliance for Eating Disorders helpline, 988, or other resources as needed.

Chapter Review Answers

1. The heart and the lungs. 2. Heart-and-lung moves (running, biking, swimming), muscle-power moves (climbing, lifting), stretching moves (yoga, reaching), balance moves (one-foot standing, gymnastics). 3. Practice strengthens the body too — but only with rest, food, and sleep. Muscles get stronger during rest. 4. Practice → rest + eat → sleep → a little stronger; repeat. 5. Normal: any two of heart fast, breath deep, sweating, warming up, good tired. Stop: any two of sharp pain, can't catch breath, dizzy, hit head, sick stomach. 6. Tell a trusted grown-up.

Discussion Prompts

Open-ended questions to ask the child after the chapter:

1. What is one move you can do now that you could not do a year ago?
2. The Lion says muscles get stronger during rest, not during the move. Does that surprise you?
3. Which of the four kinds of moves do you do the most? The least?
4. Have you ever had a "good tired" feeling after moving? What was it like?
5. Have you ever had a "hurt tired" or stop signal during movement? What did you do?
6. The Lion says movement is for joy and capability, not for appearance. What does that mean to you?
7. Who is a trusted grown-up you would go to if a body or movement worry came up?
8. The Bear, the Turtle, the Cat, and the Lion all agree: food + movement + sleep + rest = strong. Which one feels easiest in your life right now? Which feels hardest?

Common Child Questions

• "Why do my muscles hurt the day after I run hard?" Mild soreness the day after a hard move is normal — it is your body in the rebuilding part of the cycle. The soreness usually goes away in a day or two and is part of getting stronger. If it is a sharp pain or does not go away, that is different — tell a grown-up.
• "Should I drink a protein shake to build muscle?" Kids your age do not need protein shakes. The Bear taught you that real food has plenty of protein — eggs, meat, fish, beans, milk, nuts. Your body uses what comes from real food. Specific supplements are a conversation for grown-ups with a doctor.
• "How much exercise is too much for a kid my age?" Most kids your age do well with about an hour of moving across the day. More than that is often great, especially if it is varied. Signs of too much: hurt tired that does not go away, frequent injuries, dread of activities you used to love, sleep changes. Tell a grown-up if any of these come up.
• "My friend is way better than me at sports. What can I do?" Practice. Patiently. Different bodies progress at different rates, and the kid who is great at age 10 is not always the kid who is great at age 18. The Lion never compares. Find what you love and practice it because YOU love it.
• "What if I hate PE?" Tell a trusted grown-up. PE can be hard for many reasons — being compared, feeling watched, having a hard day, a teacher who pushes too much, social stuff. Your grown-up can help you figure out what is making it hard and what might help.
• "My coach yells at me. Is that okay?" A coach giving feedback is fine. A coach who shames you, makes fun of your body, or yells in ways that scare you is NOT okay. Tell a trusted grown-up at home, not at the practice. Grown-ups at home can talk to the coach or find a different situation.
• "Why does my heart race when I run? It feels like it might explode." It will not. Your heart beating fast during running is normal and means your heart is doing its job. Strong-hearted kids notice it but trust it. If you ever feel chest pain, faintness, or your heart "skipping" in a scary way, tell a grown-up immediately.
• "My body feels too tired even after I sleep. What does that mean?" Tell a trusted grown-up. The Cat (G4 Sleep) said the same thing in that chapter. Daytime tiredness despite enough sleep is a pattern worth talking about with a grown-up and possibly a doctor.
• "What if I see a video about exercising to look a certain way?" Tell a trusted grown-up. Movement-for-appearance content reaches kids your age more and more, and lots of it is not good for kids. Grown-ups can help you sort through what you saw and protect you from the harmful parts.

Parent Communication Template

Dear families,

Your child is beginning Chapter 1 of the Grade 4 CryoCove Library Coach Move curriculum — How Your Body Gets Stronger. This is the second chapter in Coach Move (the Lion)'s K-12 spiral, building on the Grade 3 chapter Moving and Your Body and connecting closely with the just-shipped G4 Brain (How Your Brain Works) and G4 Sleep (How Sleep Works) chapters.

What the chapter covers:

• How the body moves — muscles, bones, joints (from G3) plus the heart and lungs as the energy team for movement
• The four kinds of moves named by job: heart-and-lung moves, muscle-power moves, stretching moves, balance moves
• The stronger-getting cycle: practice + rest + food + sleep = real strength over weeks and months
• That muscles get stronger DURING REST, not during the move itself
• Seven things that help most kids get stronger
• Normal moving signals (heart fast, breath deeper, sweating, good tired) vs stop signals (sharp pain, can't catch breath, dizzy, hit head)
• Pacing — a new G4 concept for long activities
• That movement is for FEELING good, for what your body can DO, for the joy of it — never for changing how the body looks

Tone: The chapter is strong, warm, encouraging, and inclusive. The Lion opens with the body-first invitation ("Wiggle your fingers.") that returning readers will recognize from Grade 3. Kids who use wheelchairs and other mobility supports are explicitly named in all four kinds of moves. The Lion never compares one child to another and never frames movement around appearance.

What this chapter does not teach: bone or muscle counts (those arrive at Grade 6), heart-rate math, aerobic/anaerobic technical naming, VO2max, training periodization, sport-specific applications, body composition / weight / BMI / appearance framing. The AAP/WHO 60-minutes-per-day recommendation is presented as a range, not a rule.

End-of-chapter activity: Your child will spend one week on a small movement-practice project — picking one skill, practicing 4-5 days with 1-2 rest days, tracking how they feel, noticing the four kinds of moves they do daily, and sharing with a trusted grown-up. The lived experience of the stronger-getting cycle (including rest days) is one of the chapter's most important takeaways.

A note on Lesson 3: Lesson 3 covers listening to your body and includes preventive framing for movement-and-body-image worries. Ages 9-10 are entering the developmental window where social-media body content, peer comments, and family table comments begin landing as body-image messages. The chapter handles this preventively, never introducing weight or body-shape as topics, and routing any concerning patterns to trusted grown-ups, with crisis resources (988, Crisis Text Line — text HOME to 741741, SAMHSA, National Alliance for Eating Disorders at 866-662-1235, and 911 for emergencies) introduced at age-appropriate "grown-ups can call these if you need help" framing. The 911 framing introduced at G3 Move (the first time 911 appeared in the curriculum) carries forward at G4. If you would like to read Lesson 3 alongside your child, that is welcome.

Warning signs we ask families to notice: sudden food category restriction, compulsive or secret exercise, negative body talk in connection with movement, avoidance of body-visible activities, comparison comments, sleep or mood changes alongside movement changes, and any mention of wanting to hurt themselves or hate their body. If you notice any of these, please contact your pediatrician. The National Alliance for Eating Disorders helpline (866-662-1235) is also available for parents looking for guidance.

If you have any questions, please reach out to your child's teacher or to us at the CryoCove team.

Warmly, The CryoCove Curriculum Team

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Illustration Briefs

Lesson 1.1 — The Moving Team Placement: After "The Lion Watches Again." Scene: A simple cutaway illustration of a child mid-action (running, climbing, or dancing) with three labeled "teammates" inside the body highlighted in soft colors. 1) The heart (a soft red shape in the upper-center of the chest); 2) the lungs (two soft pink shapes around the heart); 3) a muscle in the leg (a soft pink shape on the upper thigh). Curving lines or arrows show how they work together: an arrow goes from lungs to heart, then from heart to the muscle. Labels: "Heart — pumps blood to muscles," "Lungs — pull air in for your muscles," "Muscle — uses what heart and lungs deliver to move bones." Coach Move (the Lion) stands proudly beside the child, one paw raised. Show diverse skin tones and a variety of body types and abilities throughout the chapter — including a kid using a wheelchair in at least one illustration. Aspect ratio: 16:9 web, 4:3 print.

Lesson 1.2 — The Stronger-Getting Cycle Placement: After "The Bear, the Turtle, the Cat, and the Lion Agree." Scene: A simple four-panel illustration showing the stronger-getting cycle. Panel 1: a child climbing a playground structure, looking determined (a little effort visible — slight strain, focused expression). Label: "1. Practice a move." Panel 2: the same child sitting on the grass, drinking water, looking pleasantly tired. Label: "2. Rest and eat." Panel 3: the same child sleeping peacefully in bed, with soft golden light from a window. Label: "3. Sleep — body rebuilds." Panel 4: the same child climbing the same playground structure, but now further or higher than in panel 1, smiling. Label: "4. A little stronger. Repeat." A curving arrow shows the cycle going around. Coach Move (the Lion) stands beside the panels, looking proud. Show diverse skin tones; include a kid using a wheelchair in one of the panels. Mood: warm, ordinary, never aspirational-athletic. Aspect ratio: 16:9 web, 4:3 print.

Lesson 1.3 — Every Body Has Its Own Pace Placement: After "Bodies Are All Different." Scene: A simple, warm scene of a group of kids at a school recess or a community space, doing different kinds of moves at different paces. Show: a kid running fast across a field; a kid on a swing being gently pushed by another kid; a kid in a wheelchair laughing and zooming on a smooth playground path; a kid stretching alone in a quiet corner; a kid climbing a low structure slowly and carefully; a kid balancing on a low beam. All kids look engaged in their own thing, none look pressured. Coach Move (the Lion) stands at the edge of the scene, watching warmly. Small text reads: "Every body has its own pace. The Lion is in your corner — yours, however you move." Mood: inclusive, ordinary, warm. Show wide range of skin tones, body sizes, ages within G4 (9-10), and abilities. Aspect ratio: 16:9 web, 4:3 print.

Optional — Lesson 1.1: Four Kinds of Moves Placement: After "Four Kinds of Moves." Scene: A simple four-panel illustration. Panel 1 (Heart-and-lung): a child running, breath visible as a small cloud, looking energized. Panel 2 (Muscle-power): a child climbing a rock wall or carrying groceries up stairs. Panel 3 (Stretching): a child in a comfortable stretch, hands reaching toward toes or arms overhead. Panel 4 (Balance): a child standing on one foot or balancing on a low beam, arms out. Above the panels, soft text reads: "Four kinds of moves. All for every body." Coach Move (the Lion) stands at the edge, smiling. Show diverse skin tones; include a kid using a wheelchair in one panel (the Heart-and-lung panel works well — wheelchair sprinting is a great example). Aspect ratio: 16:9 web, 4:3 print.

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Citations

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7. Bailey, D. A., McKay, H. A., Mirwald, R. L., Crocker, P. R. E., & Faulkner, R. A. (1999). A six-year longitudinal study of the relationship of physical activity to bone mineral accrual in growing children: the University of Saskatchewan bone mineral accrual study. Journal of Bone and Mineral Research, 14(10), 1672-1679.

8. American Academy of Pediatrics, Council on Sports Medicine and Fitness and Council on School Health. (2011). Climatic heat stress and exercising children and adolescents. Pediatrics, 128(3), e741-e747.

9. Murphy, N. A., & Carbone, P. S.; Council on Children with Disabilities. (2008). Promoting the participation of children with disabilities in sports, recreation, and physical activities. Pediatrics, 121(5), 1057-1061.

10. American Academy of Pediatrics, Council on Sports Medicine and Fitness. (2010). Strength training by children and adolescents. Pediatrics, 121(4), 835-840.

11. Halstead, M. E., Walter, K. D.; Council on Sports Medicine and Fitness. (2010). Sport-related concussion in children and adolescents. Pediatrics, 126(3), 597-615.

12. Hillman, C. H., Erickson, K. I., & Kramer, A. F. (2008). Be smart, exercise your heart: exercise effects on brain and cognition. Nature Reviews Neuroscience, 9(1), 58-65.

13. Biddle, S. J. H., & Asare, M. (2011). Physical activity and mental health in children and adolescents: a review of reviews. British Journal of Sports Medicine, 45(11), 886-895.

14. Lubans, D., Richards, J., Hillman, C., Faulkner, G., Beauchamp, M., Nilsson, M., Kelly, P., Smith, J., Raine, L., & Biddle, S. (2016). Physical activity for cognitive and mental health in youth: a systematic review of mechanisms. Pediatrics, 138(3), e20161642.