Muscles at Work

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Muscles at Work

03 September 2025
By: Basma Fawzy
Health - Sports - Exercise - Bones - Muscles

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Since early childhood, we are often told to eat so that our muscles would grow. However, our idea of muscles reflects unrealistic fantasies about strength. We dream of having huge muscles as Popeye whose biceps grow bigger when he eats spinach to show that we are superheroes. As a result, the truth about muscles, their function, and how sports can help us improve them is often unnoticed. Today, we leave Popeye’s fictional world and provide an overview of the types of muscles, and what sports can do.

What normally comes to mind when muscles are mentioned are skeletal muscles; those responsible for motion and carrying heavy items. However, those are not the only type of muscles that we have; we actually have three types of muscles: cardiac, smooth, and skeletal. Smooth muscles are involuntary; their movements are beyond conscious control.

The bladder is a smooth muscle; when it contracts, it pushes urine outside the body. The uterus is also a smooth muscle; this muscle is responsible for pushing the baby outside the mother’s body. The stomach is another smooth muscle; its contraction and relaxation control the movement of food inside the body. The heart is also a muscle; it is the cardiac muscle and it is the most powerful muscle in the human body. With every beat, it pumps out about 71 grams of blood, which makes up to 9450 liters of blood per day. It works every second of every minute of your life, non-stop. The heart muscle is, of course, an involuntary muscle; it ensures the organs receive enough blood to function properly.

Muscle structures vary according to their type. Smooth muscles are nonstriated; they do not have the stripy appearance characteristic of skeletal muscles. Its contractions are slow and triggered by neurogenic impulses. Cardiac muscles, on the other hand, are striated; they are controlled by “the autonomous nervous system” and even without any nervous input, contractions take place thanks to cells in the heart known as the “pacemaker”. The heart muscle is strong due to the presence of huge amounts of mitochondria, which are organelles responsible for generating power in the cells and sufficient blood supply.

To perform any movement, from playing football, tennis, lifting weights, or just typing words on the keyboard, skeletal muscles play a significant role. They are surrounded by a layer known as the “Epimysium”, which prevents friction with other muscles or bones. Every skeletal muscle has bundles of fibers known as “fascicle”; again, muscle fiber is protected by a tissue called “Perimysium”. Each bundle has fibers; their number depends on how large the muscle is. The diameter of muscle fiber ranges 10–80 micrometers, and is covered by a tissue called the “Endomysium”.

Between the muscle fiber and the endomysium lies the fiber cell membrane, sarcolemma; beneath it lies the sarcoplasm, which is this type of cell’s cytoplasm—a fluid found in most cells containing fat, glycogen, and the mitochondria, which is the power machine of the cell. As for the muscle fiber, it has cylindrical organelles called “myofibril”; the fiber contains hundreds to thousands of myofibrils which in return contain bundles of Actin and Myosin—the proteins responsible for contraction. Nerve impulses pass from the sarcolemma through the myofibril.

Movement

When we play sports or just move around, we move when nerve impulses reach the muscle. Once a signal reaches the muscles, chemical reactions start inside the muscles; they force the fibers to re-organize themselves creating contractions. Once the signal disappears, the muscle relaxes.

There are more than 600 muscles in the body, most of which are connected to bones; those muscles are responsible for every single movement you make. For example, when we run, we use many muscles such as the quadriceps, hamstrings, glutes, hip flexors, and calf muscles. When we run, the main muscle that moves is the quadriceps, located at the front of the thighs; it helps in bending and extending the knees, and protects your knees when your feet hit the ground. Even the rectus abdominus muscle^* that seems insignificant during running is vital because it helps the body in twisting and turning.

When we think of muscles, we only think of movement; however, this is not the only function of skeletal muscles. Beside movement, skeletal muscles control stability; muscles known as the trunk—including abdominal muscles, pelvic muscles, and back muscles—control the balance of the body. Moreover, muscles maintain the body posture; weak muscles lead to misalignment. Strengthening your muscles is key to maintain not only good posture, but also to prevent joint injuries, as people are more likely to harm joints if their muscles are weak and do not provide sufficient support.

Sports and Stretching

Keeping muscles healthy is a priority to anyone who wants to be healthy. Muscles love challenges; playing sports and exercising regularly are, thus, important. When it comes to muscles, strength training is always mentioned, such as, weight lifting, resistance exercises, pushups, squats, lunges, planks, or anything that targets muscles.

Some exercises target one group of muscles, these are known as Isolation Exercises. Other exercises target different muscles simultaneously, and those exercises are compound exercises. Of course, the more muscles are worked is better; working many muscles at the same time improves the body’s overall strength, coordination, and performance.

Swimming is one of the major sports that use many muscles at the same time. Maintaining muscle health can also be achieved through stretching, which improves muscle flexibility and range of motion. Professional athletes and trainers know the importance of stretching; after working their muscles, they stretch. Yoga is a training program that includes muscle stretching beside its spiritual and mental benefits. Another training program is Pilates, which also stretches the muscles. Playing sports or exercising without stretching is ineffective; start stretching for healthier muscles.

Muscles and Hormones

Some people care about how large their muscles are, and to increase muscle volume, you should work hard. Bodybuilding is among the exercises that increase muscle size; it includes moving heavy loads, which forces the muscles to contract. The muscle contractions raise the number of contractile filaments, which in the end increases the muscle size.

Some other people are not into working hard to improve their muscle size and performance; they, unfortunately, resort to hormones to increase their muscle size without any effort. They take Anabolic Steroids that are derived from Testosterone—the male hormone—which is responsible for maintaining and promoting muscle growth. Magical as it may seem, there are serious side effects that arise from taking Anabolic Steroids, depending on the dosage and age. If taken by adolescents, Anabolic Steroids inhibit growth; they also raise cholesterol level and damage the liver, and may cause strokes and heart attacks.

Another substance that some athletes use to improve their performance is Human Growth Hormone (HGH). This hormone improves athletic performance and endurance; however, like Anabolic Steroids, it has many side effects. Side effects include swelling of muscle tissue, joint pain, as well as increased risk of diabetes and colon cancer.

Now that we know the structure of our muscles and how to keep them healthy, exercising should be a priority in our life. Exercising does not just make our biceps muscles large like Popeye’s; it helps us maintain a good posture, and a good posture protects our joints from injuries. Nothing improves muscles better than getting them into action; so play sports and stretch to keep your muscles healthy.

Glossary

*Rectus abdominus muscle also known as the "abdominal muscles" or "abs", is a paired muscle running vertically on each side of the anterior wall of the human abdomen, as well as that of some other mammals.

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