Physical activity is an important part of good health. When done as exercise—that is, in a regular and planned way—it can give you energy for your daily activities and keep your weight at a healthy level. It strengthens both muscles and bones, raises heart and lung function, and can even build self-confidence—making you feel better about yourself!

Check out these students at their school gym program. One student says that working her "abs" (the stomach muscles) is a "stress buster," which means it reduces the stress in her life. Watch the video to see what kinds of exercise students do to keep in shape.

Click "View" on the left to watch the video. After you watch the video, list three types of physical activities that are good for your health.

Goals
Here are the big ideas you will learn about in this lesson:

• Regular physical activity is important to improve and maintain your health.
• Physical activity can help both your body and your mind.
• Changes occur within your body when you exercise.

Strategies
You will be using many reading and writing strategies to complete this lesson. The key strategies that you will focus on are:

• Determining important information
• Making connections
• Categorizing basic facts and ideas
• Constructing summaries

• fitness
• respiration

There are four basic types of physical activity.

• Aerobic activities make your heart and lungs stronger and able to work better. Your heart beats faster and you breathe harder than usual. Examples: running, swimming, walking, and bicycling.
• Muscle-strengthening activities improve your muscles' strength, power, and endurance (the ability to continue working). Examples: doing pull-ups and sit-ups, lifting weights, and climbing stairs.
• Bone-strengthening activities help make your bones strong. The bones in your feet, legs, or arms support your body’s weight, and your muscles push against your bones. Examples: running, walking, jumping rope, and lifting weights.
• Stretching improves your ability to fully move your muscles and joints. Examples: touching your toes, side stretches, and yoga.

Write down one to two sentences about the type(s) of physical exercise you do—or want to do—and why.

Exercise changes not only the way you look on the outside, but also the way your insides work. For example, blood vessels become more elastic when you exercise. This means they can easily expand to allow more blood to flow while you are exercising. They can also narrow when you stop and the blood flow goes back to normal.

In this video, watch how a group of people improved their fitness levels by training for and running a race. They started out with average or below-average fitness and became marathon runners.

Click "View" on the left to watch the video.

After you watch the video, list three changes that occur in the body as a result of exercise.

As mentioned in the previous video, an important change that occurs in your body when you exercise affects mitochondria (my-toh-KON-dree-uh)—tiny structures deep inside your cells. Mitochondria are organelles, or parts of a cell that perform a particular function. Through a process called respiration, mitochondria turn fats and carbohydrates from the food you eat into energy your body can use. This animation shows in detail where mitochondria exist inside a muscle cell.

Click "View" on the left to watch the video.

As you exercise, mitochondria increase in number, grow larger, and make more energy. This means you can run, cycle, or swim faster and longer. But these additional mitochondria need additional oxygen for respiration to occur. Here's how they get it:

• As you push yourself harder in an activity, oxygen will travel from your lungs through the flowing blood to the working muscle.
• Your blood vessels, being more elastic because you exercise, expand.
• This allows your heart to pump more blood using less energy.
• As you push yourself harder, you breathe more deeply and take in more air—including the added oxygen that mitochondria need.

All of these actions strengthen your muscles, heart, and lungs and improve the way your body works.

You don’t need to train for a marathon to get fit. But you may get a great feeling—like you’ve just won a race—by making exercise a regular part of your everyday life. When you exercise, your brain releases chemicals called endorphins (en-DOR-finz) that can make you feel happier and more relaxed.

In this video, Minnie has started to use exercise to improve her life—and manage her diabetes. (Diabetes is a disease in which the body can’t turn sugar in the blood into energy the cells need.) Exercise also helps control or prevent other medical conditions, including high blood pressure and obesity, a condition in which the body collects too much fat. Watch to see what Minnie learns about the value of exercise.

Click "View" on the left to watch the video.

After you watch the video, write down one to two sentences to describe what Minnie learned about how exercise can improve her life.

As Minnie’s coach says, the key to keeping physically active is finding things you like to do. If you don’t like jogging, you could ride a bike or skateboard instead. If team sports like basketball or soccer don't interest you, try an individual sport like tennis or bowling. If dancing is your thing, turn up the music!

Government health guidelines suggest that children and teens get at least 60 minutes of exercise a day. But you don’t have to do it all at one time. And you don't have to find a gym or play organized sports to get exercise. Take the stairs instead of using elevators or escalators. Or walk to the store or a friend’s house instead of taking the bus or driving.

If you already exercise, what makes you want to? If you don’t exercise, why not?

Doctors or health care providers measure such things as body temperature, heart rate, and what’s in the blood to learn more about a patient’s overall health. To do this, they use tools, such as thermometers and X-ray machines. Now read about some of the different measurements and tools that are used to determine someone's physical fitness.

Click "View" on the left to read the passage. After reading the passage, answer the question below.

What are two types of measurements that doctors can perform to determine your fitness level? How can you and your doctor use these measurements to improve your health?

The videos you have watched and the text you have read explained the effects that exercise has on the body and showed some different activities that people do to improve their health.

Now show what you have learned so far about exercise and the body by answering these three questions. Be sure to save all your answers before you go to the next screen.

You will now check your understanding of the vocabulary words for this lesson by placing them in sentences. Click "View" on the left to begin the activity.

Before moving to the next screen, choose two words from the vocabulary list and write a new sentence for each word.

Vocabulary words: aerobic, blood vessels, diabetes, fitness, respiration

As you saw and read on the previous screens, regular exercise produces many positive physical and mental changes. In this activity, you will sort information according to two categories:

• if it describes a mental or physical benefit (or gain) received from doing exercise
• if it describes a mental or physical symptom of inactivity, or too little exercise

Click "View" on the left to begin the activity. Your teacher will review the answers with you.

Then, before moving on to the final assignment, you may want to watch this lesson's videos again or reread the passage.

Fit for Life

Video: 1m 04s

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How the Body Responds to Exercise

Video: 3m 12s

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Powerhouse of the Cell

Video: 0m 23s

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Minnie Works It Out

Video: 3m 05s

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Measuring Health and Fitness

Document

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In this lesson, you have learned that exercise causes changes in the body that can improve your overall physical and mental health. You will now write an essay that shares what you have learned and what you think about it.

Begin by reviewing your notes. Click "review my work" above and view or print out the screen that pops up.

Final Assignment Instructions

• Click Powering Your Body With Exercise—Final Assignment (PDF).
• Choose one of the topics in the PDF and write an essay.
• Organize your response so that it includes at least three supporting details that you have learned from the reading passage, videos, and other materials in this lesson.
• Use at least three vocabulary words (or a form of the words) as part of your supporting details. For example, for the word jump, you could use jumps, jumped, or jumping.