The Process of Muscular Hypertrophy

Being active is crucial for overall health, and it is also the best way to build skeletal muscle. This article is all about the muscles, getting to know what they represent, their function and the process of muscle growth.

In the human body we have more than 600 muscles. All of them functioning together form the muscular system that permits movement of the body, maintains posture, and circulates blood throughout the body. Although there are different types of muscles, here we will talk exclusively about the skeletal muscles, also known as voluntary muscles, meaning we can control how and when they move and work.

How It Works

We, humans, are biologically programmed to thrive on activity. Our muscles tend to shrink if they are not regularly exposed to some kind of resistance. This process is also known as muscular atrophy (decrease of the total mass of a muscle). 

On the other hand, muscular hypertrophy (an increase of the total mass of a muscle) means exposing our cells to higher workloads than they are used to. When muscular hypertrophy happens, for example when we are working out, the level of circulation increases, and our muscles get that pumped-up look. 

With every basic workout, the muscle cell undergoes another kind of cellular change. As we expose the muscle to stress, it experiences microscopic damage, which in the case where you want muscle growth, is a good thing. The injured cells release inflammatory molecules called cytokines that activate the immune system to repair the injury. This cycle of damaging and repairing the muscle makes them bigger and stronger. 

The skeletal muscle is composed of filamentous myofibrils and sarcomeres that form a muscle fiber and are the basic units of contraction.  Each myofibril is composed of about 1500 adjacent myosin filaments ( contractile protein ) and 3000 actin filaments ( contractile protein ), which are large polymerized protein molecules that are responsible for muscle contraction. Every movement represents a contraction. 

After a workout, our body repairs or replaces damaged muscle fibers through a cellular process where it fuses muscle fibers together to form new muscle protein strands or myofibrils. These repaired myofibrils increase in thickness and number to create muscle hypertrophy. Muscle growth occurs whenever the rate of muscle protein synthesis is greater than the rate of muscle protein breakdown.  That’s why it is important to have the right diet while working out. The diet should compensate for every nutrient lost due to working out.

An image of a muscle filament.

If we do not provide our bodies with adequate rest or nutrition, we can actually reverse the anabolic process and put our bodies into a catabolic or destructive state. The response of muscle protein metabolism to a resistance exercise bout lasts for 24 - 48 hours; thus, the interaction between protein metabolism and any meals consumed in this period will determine the impact of the diet on muscle hypertrophy.

The Importance of Hormones 

Our hormones like testosterone, human growth hormone, and insulin growth factor, also play a role in muscle growth and repair.

Testosterone is responsible for increased deposition of protein everywhere in the body, but especially in the muscles. A study shows that even a male who participates in a small sports activity but who nevertheless has a normal level of testosterone will have muscles that grow about 40% larger than those of a comparable female without testosterone.  In addition, testosterone can increase the presence of neurotransmitters in the muscle fibers, which can help to activate tissue growth. 

Men and women build muscles differently. That’s because testosterone plays a big role in muscle development. While both sexes have testosterone in their bodies, men have more of this hormone. However, studies have shown that both men and women have similar responses to strength training.

Growth hormone helps to trigger fat metabolism for energy use in the muscle growth process. Also, the growth hormone stimulates the uptake and incorporation of amino acids into protein in skeletal muscles.

Insulin growth factor also stimulates muscle growth by enhancing protein synthesis and facilitating the entry of glucose into cells. It plays a primary role in regulating the amount of muscle mass growth and promoting muscle cell repair.

Fast Muscular Hypertrophy Is Very Unlikely

Muscle hypertrophy takes time and is relatively slow for the majority of people. People will generally not see visible growth for several weeks or months as most initial changes are due to the ability of your nervous system to activate your muscles.

In addition to that, different people have different genetics, which ranges from hormonal output, muscle fiber type and number of muscle fibers. To ensure you’re doing your best to grow muscle, muscle protein synthesis must exceed muscle protein breakdown. This requires that you take in an adequate source of protein (especially essential amino acids) and carbohydrates to help facilitate the cellular process of rebuilding broken-down muscle tissue. Visible muscle growth and evident physical changes in your body’s muscle structure can be highly motivational which is why understanding the science behind how muscles actually grow is important if you want to see and feel the fruits of your labor.

Summary 

The most adaptable tissue in the human body is skeletal muscle, and it is remarkably remodeled after continuous, and carefully designed, resistance exercise training programs. Resistance training leads to trauma or injury of the cellular proteins in muscle. This prompts cell-signaling messages to activate a cascade of events leading to muscle repair and growth. The adaptation of muscle to the overload stress of resistance exercise begins immediately after each exercise bout, but often takes weeks or months for it to physically manifest itself in noticeable physical change. All studies show that men and women respond to a resistance training stimulus very similarly.

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