Why Muscle Matters

Getting Started: Talking About Your Goals

Let's talk about your goals for staying active! Think about these questions:

• How is your goal going so far?
• What could you do better to reach your goal? (These are called "grows.")
• What are you already doing well? (These are called "glows.")

Guideline: Be active more often, and spend less time sitting still.

Here's a fun way to review what you've learned about staying healthy. Try one of these:

1. Popcorn Game: Take turns quickly naming all 8 healthy habit guidelines.
2. Charades: Act out a guideline without talking while others guess what it is.
3. Two Truths and a Lie: Can you spot the lie?
4. Truth: If you don't use your muscles, you will lose them as you get older.
5. Truth: Building muscle helps make your bones stronger.
6. Lie: Only athletes need to exercise and build muscle. (Everyone needs to!)

Think about or write down:

• What are your favorite exercises?
• Which muscles do those exercises work?
• Which exercises make your muscles stronger?
• How often do you do muscle-strengthening exercises?

This lesson will explain why building muscle, strength, and endurance (the ability to keep going without getting tired) is important for everyone.

Key Words to Know

• Exercise: Moving your body on purpose, in a planned and repeated way, to use energy.
• Fitness: Being able to do your daily activities with energy, without getting tired too fast.
• Insulin: A helper made by your pancreas (an organ in your body) that moves sugar from food into your cells so you can use it for energy.
• Body composition: The different parts that make up your body, like fat, muscle, and bone.
• Muscle-strengthening exercise: Exercise that makes your muscles work harder than normal by pushing or pulling against something heavy.
• Bone-strengthening exercise: Exercise that puts a gentle push or pull on your bones to make them stronger.
• Muscular strength: How much force you can use, 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 that mixes strength exercises with short bursts of cardio (heart-pumping) exercise.
• Repetition: One complete time you do an exercise, like one push-up.

Warm-Up: Meet Your Muscles

Exercise means moving your body in a planned way that uses energy. Let's look at some major muscles in the body and the exercises that work them:

1. Trapezius – near your neck – strengthened by shrugs
2. Deltoids – top of your arm – strengthened by shoulder presses
3. Pectoralis major – your chest – strengthened by the bench press
4. Latissimus dorsi – your back – strengthened by lat pulldowns
5. Biceps – front of your arm – strengthened by curls
6. Triceps – back of your arm – strengthened by pulldowns
7. Abdominals – your stomach area – strengthened by crunches
8. Quadriceps – front of your thigh – strengthened by squats
9. Hamstrings – back of your upper leg – strengthened by lunges
10. Gastrocnemius (calves) – back of your lower leg – strengthened by calf raises
11. Gluteus maximus – your rear end – strengthened by leg presses

Now that you know some major muscles, let's learn how they connect to your fitness — your ability to do everyday tasks 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 — and you use them for everything, from running to getting out of bed to pumping blood through your body!

Some muscles you control on purpose, like when you decide to lift your arm. Other muscles work automatically, without you even thinking about them. Can you guess one? Your heart is a muscle that works all by itself!

Why is building muscle important for your fitness? Here are some reasons:

• It helps you grow stronger and move better.
• It helps make your bones stronger.
• It lowers your risk of getting hurt.
• It helps keep your heart and lungs healthy.
• It helps your body use insulin better. Remember, insulin helps move sugar from food into your cells for energy. When your body responds well to insulin, it needs less of it to keep your blood sugar at a healthy level.
• It helps you manage your weight and avoid obesity (having too much extra body fat).
• It can help lower feelings of anxiety and sadness.

You should be active for 60 minutes every day. On at least 3 of those days, include muscle-strengthening and bone-strengthening exercises.

Muscle-strengthening exercises make your muscles work harder than usual by pushing or pulling against something. Bone-strengthening exercises put a gentle force on your bones to make them stronger.

Here are some examples of muscle- and bone-strengthening 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 and skipping
• Jumping jacks
• Sprinting
• Surfing
• Sports like gymnastics, basketball, volleyball, tennis, and football

Real-Life Connection: Strength and Endurance

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

• Muscular strength is how much force you can use or how much weight you can lift.
• Muscular endurance is how many times, or how long, you can keep using force before getting tired.

Having muscular strength helps you in everyday life. It makes it easier to lift, push, or pull heavy things — like grocery bags, luggage, or a heavy backpack.

Ways to build muscular strength include:

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

Muscular endurance matters too. When your muscles have strong endurance, you can keep doing an activity for a longer time without stopping.

Ways to build muscular endurance include:

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

Muscular strength and endurance work together. If you improve one, the other usually improves too. Most exercises actually build both at the same time.

Try this: Imagine erasing a whiteboard for two minutes straight.

• Pushing and holding the eraser against the board uses your muscular strength.
• Moving the eraser back and forth for two whole minutes uses your muscular endurance.
• You need both — strength to hold it and endurance to keep going. Without strength, you can't have endurance, and most tasks need both!

Push-up experiment: Try doing 10 push-ups with your hands wider than your shoulders. Then try 10 push-ups with your hands at shoulder width.

Push-ups aren't just for your arms and chest — they also work your core (stomach and back muscles).

Even though both types of push-ups use the same muscles, they feel different! Moving your hands closer together makes your chest and triceps work harder — though this can be tougher to do and puts more strain on your elbows. Moving your hands wider apart still works your chest and triceps, but focuses more on the outer part of your chest.

Doing both kinds of push-ups helps keep the muscles in your upper body growing evenly and staying balanced.

Hands-On Activity: No Weights, No Problem

Now it's time to try circuit training! Remember, circuit training mixes strength exercises with short bursts of cardio exercise.

In a circuit workout, you do strength exercises one after another with little or no rest in between. You don't need weights — you can do push-ups, lunges, or squats instead.

Between sets of strength exercises, add in a cardio exercise like jumping jacks, speed skaters, or jogging in place with high knees.