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What Is Muscle?

One of the major reasons that we workout is to grow muscle, but what is muscle?

Muscle is “a band or bundle of fibrous tissue in a human or animal body that has the ability to contract, producing movement in or maintaining the position of parts of the body” (

In simpler words, muscle functions as the source of motion and power in our bodies. The main responsibility of muscle is maintaining posture, movement of internal organs, and locomotion. The body consists of a lot of muscles, about 650 total. These 650 muscles account for roughly half of our body weight. The elastic tissue known as muscle is a stretchy fibrous material. These fibers are made of fibrils, which make a larger mass, such as the bulge of our biceps. The nerves in our bodies send a signal to the fibers that make up our muscle that command it to contract. The more fibers that are present, the stronger the muscle is.

A quick rundown of different types of muscles :

  • Skeletal muscles – These striated muscles move the external parts of the body and the limbs. Skeletal muscles give us our shape; cover our bones and our skeleton. They’re attached to tendons that are attached to our bones or directly to our bones. The skeletal muscles contract when we move our head, fingers, arms, legs, faces, eyes, etc. We control these muscles; they only move when we tell them to. Skeletal muscles maintain our posture, hold our heads up and move our fingers. These muscles keep our bones in the right position so our joints don’t collapse. Roughly 42% of male body mass and 36% of female body mass consist of skeletal muscle ( Skeletal muscles regulate our body temperature by contracting and releasing our muscles.

  • Cardiac muscles – These striated muscles are responsible for heartbeat. Cardiac muscles only exist in the heart. These muscles work from when our heart develops in the womb to when our lives end. If these muscles cease working we cease living. Cardiac muscles contract so that blood comes in and out of the heart.

  • Smooth muscles – These muscles are responsible for movements in the intestines, stomach, arteries and organs. These muscles are activated unconsciously. Smooth muscles contract to aid in bowel movement, uterus contractions, pupil constriction, bronchial expansion, and the arrector pili in the skin to make the hair stand up when we need heat.

How to make muscles grow :

After we workout, our body repairs or replaced the damaged muscle fibers. This cellular process fuses muscle fibers together to form new myofibrils or muscle protein strands. In order for growth to happen, these now repaired myofibrils grow in thickness and number. The rate of muscle protein synthesis must be greater than the rate of muscle protein breakdown for growth to occur. A common misconception of the general population is that growth occurs when we lift weights, however, growth actually occurs when we rest.

While we are lifting or “getting swole”, we are getting a pump. The cells of our muscle swell in a restructuring process for growth. Blood rushes to fill the muscle, a process called edema, when we are in repetition. When there is tension on the muscle there will be growth by creating more muscle fibers. In order for muscle to grow, the tension applied must be a greater load of stress than what we’re accustomed to. Lifting heavier weights progressively will allow the muscle growth and strength to occur. This is where our slow-twitch and fast-twitch muscles come into play. Both are being utilized when we are lifting heavily. During heavy lifting, protein synthesis and satellite cell activation occurs.

When we are lifting, we are actually tearing down the muscle fibers in order for regrowth. During a process called hypertrophy, you create hundreds of micro tears in your muscles. This muscle damage causes a release of inflammatory molecules and immune system cells. This is the activation of satellite cells to begin doing their work. This is when we’ll feel soreness 24-48 hours after a workout. Metabolic stress causes cell swelling around the muscle. This process contributes to muscle growth, possibly without physical muscle growth.

Hormones affect muscle growth by regulation of satellite cell activity. Testosterone and insulin growth factor promote muscle growth. Testosterone increases protein synthesis, ceases protein breakdown and stimulates the other anabolic hormones required for muscle growth. Strength training releases more testosterone and makes our receptors of our muscle cells more sensitive to testosterone. There’s also a stimulation of growth hormone responses by an increase of neurotransmitters at damaged fibers, which can activate tissue growth.

Certain supplementation such as betaine and creatine have also been shown to increase muscle and body composition (Journal of the International Society of Sports Nutrition and Primed Capacity contains both betaine and creatine, as well as a handful of other high quality ingredients to help you recover faster and stronger.

The most important step in muscle growth is rest and recovery. Without proper rest or nutrition you actually reverse the process of anabolic status to catabolic status. Roughly 24-48 hours are needed for there to be an interaction between protein metabolism in the muscles. There is a limit on how much our muscles grow based on age, gender, and genetics. This is a brief lesson in the complicated topic of what a muscle is, how it works, and how to make it grow.


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