4.6: Why Muscle Matters

Let's Talk About Goals

Let's talk about your SMART goals (goals that are Specific, and easy to check).

• How is your goal going so far?
• What can you do better? (Grows)
• What are you already doing well? (Glows)

Today's Guideline: Move More, Sit Less

Today's guideline is: Move your body more often. Sit less.

• Does anyone have a goal about this?

Pick one activity to try:

1. Guideline Popcorn: Everyone calls out the 8 guidelines quickly, one after another.
2. Guideline Charades: Split into groups. Each group acts out a guideline without talking. Others guess it.
3. Two Truths and One Lie:
4. Truth 1: If you don't use your muscles, you will lose them as you get older.
5. Truth 2: Building muscles helps make your bones stronger.
6. Lie: Only athletes need to exercise and build muscles.
7. Talk or write about:
8. What exercises do you like best?
9. Which muscles do those exercises work?
10. Which exercises build muscle?
11. How often do you do muscle-building exercises?

We will learn why building muscle, strength, and endurance (the ability to keep going without getting tired) matters.

Some Words to Know

• Exercise: Moving your body on purpose, in a planned way, again and again.
• Fitness: Being able to do your daily activities with energy, without getting too tired.
• Insulin: A helper made in your body (in the pancreas) that moves sugar from food into your cells so you can use it for energy.
• Body Composition: What your body is made of — like fat, muscle, and bone.
• Muscle-strengthening: Exercises that make your muscles work harder than normal, by pushing or pulling against weight.
• Bone-strengthening: Exercises that push or pull on your bones to make them stronger.
• Muscular Strength: How much force you can push or pull, or how much weight you can lift.
• Muscular Endurance: How many times, or how long, you can keep using your muscles before getting tired.
• Circuit Training: A workout where you do a strength exercise, then right away do a heart-pumping exercise, back and forth.
• Repetition: One time you lift a weight. If you lift it 10 times, that's 10 repetitions.

Do Now: Meet Your Muscles

Exercise means moving your body on purpose, in a planned and repeated way.

Look at a picture of the body. Find each muscle, and think of an exercise that makes it stronger:

1. Trapezius – near your neck. Try: shoulder shrugs.
2. Deltoids – top of your arm. Try: shoulder presses.
3. Pectoralis Major – your chest. Try: bench press.
4. Latissimus Dorsi – your back. Try: lat pulldowns.
5. Biceps – front of your arm. Try: arm curls.
6. Triceps – back of your arm. Try: tricep pulldowns.
7. Abdominals – front, sides, and back of your middle (your "core"). Try: crunches.
8. Quadriceps – front of your thigh. Try: squats.
9. Hamstrings – back of your upper leg. Try: lunges.
10. Gastrocnemius (calves) – back of your lower leg. Try: calf raises.
11. Gluteus Maximus – your bottom. Try: leg presses.

Now that you know some of your body's biggest muscles, let's learn how they help your fitness — your ability to do daily things with energy, without getting worn out.

Good to Know: The Magic of Muscles

Did you know your body has over 600 muscles? That's a lot! You use muscles for everything — running, getting out of bed, even pumping blood through your body.

Some muscles you control, like the ones in your arms. Other muscles work all by themselves, without you thinking about it. Can you guess one? Your heart is one!

Why is building muscle important for your fitness?

• It helps you grow stronger and move better.
• It helps make your bones stronger.
• It lowers your chance of getting hurt.
• It helps your heart and lungs stay healthy.
• It helps your body use insulin better. Insulin is a helper made in your body that moves sugar from food into your cells for energy. If your body uses insulin well, it needs less of it to keep your blood sugar steady.
• It helps you manage your weight.
• It can help you feel less worried or sad.

You should be active for 60 minutes every day. On at least 3 of those days, do exercises that build your muscles and bones.

• Muscle-strengthening exercises make your muscles work harder than usual, by pushing or pulling against weight.
• Bone-strengthening exercises push or pull on your bones to make them stronger.

Can you think of exercises that build muscles and bones? Here are some:

Muscle and Bone Building Activities

Sit-ups or crunches, push-ups, pull-ups, planks, lunges, squats, wall sits, weightlifting, tug of war, rock climbing, monkey bars, resistance bands, hopping, skipping, jumping jacks, sprinting, surfing, and sports like gymnastics, basketball, volleyball, tennis, and football.

Real Life: Strength and Endurance

Muscular strength and muscular endurance are two important things about your muscles.

• Muscular strength is how much you can push, pull, or lift.
• Muscular endurance is how many times, or how long, you can keep doing something before getting tired.

How does strength help you every day? It helps you lift, push, or pull heavy things easily — like grocery bags, luggage, or your backpack.

Ways to build muscular strength:

• Resistance training (using weights or machines)
• Push-ups
• Pull-ups
• Sit-ups
• Weightlifting

Why is muscular endurance important? It lets you keep doing an activity for a longer time without getting worn out.

Ways to build muscular endurance:

• Walking, jogging, or running
• Weightlifting
• Wall sits
• Planks
• Squats

Strength and endurance work together. If one gets better, the other usually does too. Most exercises build both at the same time.

Try this: Have someone erase the board for two minutes (or draw circles on a wall with their hand if there's no board).

Think about:

• Which part used strength? Pushing the eraser against the board.
• Which part used endurance? Moving it back and forth for two whole minutes.
• How do strength and endurance work together? You need to be strong enough to press the eraser, and you need endurance to keep going for two minutes. You need both to finish many tasks.

Try this too: Pick two people.

• One person does 10 push-ups with hands placed wider than their shoulders.
• The other does 10 push-ups with hands placed shoulder-width apart.

Push-ups work your arm and chest muscles, and they're also good for your core (middle).

Did you notice both kinds of push-ups use the same muscles, but in different ways?

• Hands close together makes your chest and triceps work harder. This is tougher to do and can be harder on your elbows.
• Hands wide apart also uses your chest and triceps, but works the outer part of your chest more.

Doing both kinds keeps your upper body muscles growing evenly.

Hands-On: No Weights, No Problem

Now let's try circuit training. This means doing a strength exercise, then right away doing a heart-pumping exercise, one after another.

During circuit training, you do strength exercises back-to-back with little or no rest. You don't even need weights! You can do push-ups, lunges, or squats.

Between strength exercises, do a heart-pumping exercise like jumping jacks, speed skaters, or jogging in place with high knees.