Health Lesson: Learning About Muscles (2024)

What are muscles?

Muscles control all movement in the body. There are more than 650 muscles in the human body.

Muscles work together with bones to help you move. Muscles and bones (your skeleton) are part of the musculoskeletal (muh-skyuh-low-SKEH-luh-tl) system.

Muscle is a type of tissue, a group of cells that work together to accomplish a specific job, like movement.

You control some of your muscles, but others work on their own. Even when you sit perfectly still, muscles in your body are constantly working!

Muscles do a lot to keep your body healthy. They:

• Help you move, sit still, and stand up straight.
• Allow you to move your eyes to look around.
• Push food through your digestive system.
• Pump blood through your heart and blood vessels.

Watch this video to see heart muscles pumping blood.

• Move air in your body so that you can speak and breathe.

What are the types of muscles?

There are three main types of muscle: skeletal, smooth, and cardiac.

Skeletal muscles

Skeletal (SKEH-luh-tuhl) muscles help you move, sit up straight, and keep your balance. Skeletal muscles are sometimes called voluntary muscles because you can control them.

You can move skeletal muscles just by thinking about it and then doing it. To make skeletal muscle move, the brain sends electrical messages to your skeletal muscles. The messages tell the muscles to do things like contract or relax when you want to raise your hand, move your jaw to chew food, or kick a soccer ball into a goal.

Skeletal muscles lie under the skin. They work with your bones and joints to give your body power and strength.

Smooth muscles

Smooth muscles work to keep your body healthy without you having to think about moving them. Because you can’t control these muscles, they are sometimes called involuntary muscles. Smooth muscles help you focus your eyes, move food through your body, and go to the bathroom.

In your eyes, smooth muscles help you focus your vision and adjust to different levels of light.

Smooth muscles help you move food through and out of your body. Waves of smooth muscle contractions called peristalsis (peh-ruh-STAAL-suhs) help move food through your digestive system. Have you heard your stomach growling when you’re hungry or after you eat a meal? Those sounds are created by peristalsis!

Smooth muscles at the end of your digestive system help you push waste out of your body as feces (poop). Smooth muscles in your bladder contract and relax to hold in or push out urine (pee).

Cardiac muscles

Cardiac (KAAR-dee-ak) muscles make up the heart. Like smooth muscles, cardiac muscles are involuntary. They contract and relax automatically to pump blood through your body.

You do not need to think about telling the heart to beat. A special area of muscle in your heart sends electrical messages in a steady rhythm to help your heart beat.

What happens when muscles get hurt?

A strain happens when a muscle or tendon stretches too much or tears. Some people describe muscle strains by saying they “pulled a muscle.” If you exercise too much, too intensely, or don’t stretch enough, you may get a strain.

Strains that happen from tearing a muscle or tendon are more serious than strains from overstretching a muscle or tendon. Strains can cause pain, swelling, and bruising. Your body heals strains by creating new muscle fibers to fill in the damaged area.

If you think you have a muscle strain or tendon injury, you can try resting, putting ice on the painful area, and asking an adult for over-the-counter pain medication. Go to the doctor if your injury doesn’t get better. Doctors may treat some strains with a splint or temporary cast.

How can I help keep my muscles healthy?

Exercise to work your muscles.

Being physically active keeps your muscles healthy, which helps you work, play, and do other activities without getting hurt or tired.

You don’t need to lift weights to exercise your muscles! You can walk, jog, play sports, dance, swim, and bike. Exercising in different ways helps make sure you work all your muscles.

Remember, your heart is a muscle! Any activity that makes your heart pump blood faster will exercise this important muscle.

Avoid muscle injuries.

• Warm up and cool down. Before exercising or playing sports, warm-up exercises, such as stretching and light jogging, may make it less likely that you’ll strain a muscle. They are called warm-up exercises because they make the muscles warmer and more flexible. Cool-down exercises, such as stretching, are also very important to do after exercising. They help you to loosen the muscles that have tightened during exercise or while playing sports.
• Wear the proper protective gear for your sport, such as pads or helmets. This will help reduce your risk of injuring yourself.
• Remember to drink lots of water while you’re playing or exercising, especially in warm weather. Dehydration (dee-hai-DRAY-shn) is when your body’s water level gets too low. If you become dehydrated, you could get dizzy or even pass out. Dehydration can cause many medical problems.
• Don’t try to “play through the pain.” If something starts to hurt, STOP exercising or playing. You might need to see a doctor, or you might just need to rest for a while.
• If you have been inactive, “start low and go slow” by gradually increasing how often and how long you are active. Increase physical activity gradually over time.
• Be careful when you lift heavy objects. Keep your back straight and bend your knees to lift the object. This will protect the muscles in your back and put most of the weight on the strong muscles in your legs. Get someone to help you lift something heavy.
• Don’t try to “bulk up” by using weights that are too heavy for you. This can cause injury. Start with smaller weights and build your way up. You do not need to be able to lift very heavy weights to have healthy muscles. Instead, try doing exercises with smaller weights, but repeat the exercise more times.

Eat a healthy diet.

There is no special diet to keep your muscles healthy. Try to eat a balanced diet with fruits and vegetables, whole grains, low-fat dairy, and lean proteins.