4.6: Why Muscle Matters

National Health Education Standards (NHES)

• 1.12.7 Compare and contrast the benefits of and barriers to practicing healthy behaviors, such as staying physically active every day.
• 6.12.1–6.12.4 Setting goals to improve your health, such as increasing physical activity.

Wellness Guidelines

• Increase how often you're physically active.
• Decrease sedentary behavior (time spent sitting or inactive).

Instructions: In a group or think-pair-share format, discuss the following questions. Recognize anyone who has made progress toward their goals, and encourage anyone who wants to adjust their goal to seek one-on-one support.

Discuss your SMART Goals:

• How is it going with your current SMART goal?
• What are some ways you could improve your progress? (These are your "grows.")
• What are some ways you're already doing well? (These are your "glows.")

Guideline: Increase Frequency of Physical Activity and Decrease Sedentary Behavior

Discuss: Which guideline connects to today's lesson? Does anyone have a SMART Goal tied to it?

Choose one activity:

1. Guideline Popcorn: As a group, quickly call out all eight guidelines, one after another.
2. Guideline Charades: Split into groups. Each group gets a guideline and must silently act it out while everyone else guesses.
3. Two Truths and One Lie:
4. Truth: If you don't use your muscles, you'll lose them as you age.
5. Truth: Building muscle helps strengthen your bones.
6. Lie: Only athletes need to exercise and build muscle.
7. Discuss or journal about:
8. What are your favorite exercises?
9. Which muscles do those exercises target?
10. Which exercises count as muscle-strengthening?
11. How often do you do muscle-strengthening exercises?

This lesson covers:

• Why building muscle, strength, and endurance matters.
• Worksheets and a slides presentation.

Materials needed:

• A whiteboard eraser (or similar object)
• Tools for your circuits (a water bottle and a textbook)

Lesson sections:

• Do Now
• The Magic of Muscles
• Endurance and Strength
• No Weights, No Problem Circuits
• Exit Ticket

Key Terms

(As defined by HHS, 2008; CDC, 2004; Dor-Haim et al., 2018)

• Exercise: Body movement that uses energy and is planned, structured, repeated, and done on purpose.
• Fitness: The ability to handle daily tasks with energy and without getting tired.
• Insulin: A hormone made by the pancreas that helps glucose (sugar) from food enter your cells so it can be used for energy.
• Body Composition: A measurement of the different parts that make up your body — including total mass, fat mass, percentage of fat, lean soft tissue, and fat-free mass.
• Muscle-Strengthening: Exercises that make muscles work harder than usual by pushing or holding against force or weight.
• Bone-Strengthening: Exercises that create impact or tension on the bones.
• Muscular Strength: How much force you can apply, or how much weight you can lift.
• Muscular Endurance: How many times, or for how long, you can apply force before getting tired.
• Circuit Training: A workout style that combines a set of resistance exercises with an aerobic exercise interval right after.
• Repetition: The number of times you perform a movement, such as lifting a weight.

Do Now

Setup: Display an image of a labeled human body on the board or projector.

Instructions:
Define exercise: movement of the body that uses energy and is planned, structured, repeated, and purposeful (HHS, 2008).

As a group, locate each muscle group on the image below and name an exercise that would strengthen it:

1. Trapezius — around the neck; strengthened by shrugs.
2. Deltoids — top of the arm; strengthened by shoulder presses.
3. Pectoralis Major — chest; strengthened by the bench press.
4. Latissimus Dorsi — back; strengthened by lat pulldowns.
5. Biceps — front of the arm; strengthened by curls.
6. Triceps — back of the arm; strengthened by pulldowns.
7. Abdominals — front, sides, and back of the torso; strengthened by crunches.
8. Quadriceps — front of the thigh; strengthened by squats.
9. Hamstrings — back of the upper leg; strengthened by lunges.
10. Gastrocnemius (calves) — back of the lower leg; strengthened by calf raises.
11. Gluteus Maximus — the rear; strengthened by leg presses.

Image source: www.dreamstime.com

Discuss: Now that you've been introduced to some of the body's major muscles, let's dig into the muscular system and how it connects to overall fitness. Remember, fitness is the ability to handle daily tasks with energy and without getting tired (HHS, 2008).

Good to Know: The Magic of Muscles

Did you know the human body has over 600 muscles? That number makes sense once you consider how much we depend on our muscles — for running, getting out of bed, and even pumping blood through our bodies.

Some muscles are under your conscious control, but others do their job automatically, without you ever having to think about it. Can you think of a muscle that works on its own? The heart is one example.

Optional videos: a video on the muscular system, and a video on muscle growth.

Why might building muscle matter for your fitness?

Possible answers include (CDC, 2018):

• It helps you grow stronger and move more efficiently.
• It strengthens your bones.
• It lowers your risk of injury.
• It improves heart and lung health.
• It promotes insulin sensitivity (Bird & Hawley, 2017). Insulin is a hormone made by the pancreas that helps glucose from food get into your cells for energy (NIH, 2016). If your body is more sensitive to insulin, it needs less of it to keep blood sugar levels in check.
• It supports weight management and helps protect against obesity.
• It can reduce symptoms of anxiety and depression.

As part of your 60 minutes of daily physical activity, include muscle-strengthening or bone-strengthening exercise on at least three days a week (HHS, 2008).

• Muscle-strengthening activities make your muscles work harder than usual by pushing or holding against force or weight (HHS, 2008).
• Bone-strengthening activities create impact or tension on your bones (HHS, 2008).

Can you think of examples of exercises that strengthen both muscle and bone?

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, skipping, jumping jacks, sprinting, surfing, and sports like gymnastics, basketball, volleyball, tennis, and football.

Real-World Relevance: Strength and Endurance

Muscular strength and muscular endurance are two important qualities you need to build.

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

How does muscular strength help you in daily life? It lets you lift, push, or pull heavy things — like grocery bags, luggage, or backpacks — more easily.

How can you build muscular strength? What activities could you add to your day?

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

Why does muscular endurance matter? Strong muscular endurance lets you keep doing physical activity for longer periods.

How does muscular endurance help in daily life? What activities could build it?

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

Muscular endurance and muscular strength are closely linked — improving one tends to improve the other. In fact, most exercises build both at once.

Try this:
Have a volunteer erase the board for two minutes (or trace imaginary circles on a wall with their palm if there's no board).

Discuss:

• Which part of that activity used muscular strength? (Holding the eraser and pressing it against the board.)
• Which part used muscular endurance? (Moving the eraser back and forth for two full minutes.)
• How do the two work together? You need enough strength to hold the eraser, and enough endurance to keep erasing for two minutes. Without strength, you can't build endurance — and most tasks require both.

Try this too:
Choose two volunteers.

• Have one volunteer do 10 full push-ups with hands placed wider than shoulder-width.
• Have the other do 10 full push-ups with hands placed at shoulder-width.

Optional video: proper push-up form.

Discuss the muscles at work: Push-ups don't just work your arms and chest — they also strengthen your core.

Notice how both versions of the push-up used the same muscles but produced different results. Hand placement — wider or closer together — changes how hard specific muscles have to work.

• Hands placed closer together make the chest and triceps work harder. This version is tougher for most people and puts more stress on the elbows.
• Hands placed wider apart still use the chest and triceps, but shift more of the work to the outer chest.

Why do both versions matter? Doing both types of push-ups helps keep muscle growth in your upper body balanced (Kim Y-S, 2016).

Hands-On: No Weights, No Problem Circuits

Now it's time for circuit training — a workout that combines a set of resistance exercises with an aerobic exercise interval right after (Dor-Haim et al., 2018).

During a circuit workout, you perform resistance exercises back-to-back with little or no rest between them. Some resistance exercises that don't require weights include push-ups, lunges, and squats.

Between sets of resistance exercises, add an aerobic exercise — like jumping jacks, speed skaters, or jogging in place with high knees.