What is Hypertrophy? How Protein Builds Muscle (In Simple Terms)

by Elliot Reimers, M.S.(C), CNC | Reviewed by Advisory Board

What is Hypertrophy? How Protein Builds Muscle (In Simple Terms)

Chances are you see words like “anabolic” and “hypertrophy” plastered all over supplement labels, but what do they really mean? What is hypertrophy? How about muscle anabolism? Or anti-catabolic? And how does protein build muscle, exactly?

The terminology used to describe muscle building is not as complicated as it comes across, (much like a lot of the jargon used in science and medicine). This article will get you up to speed with a layman’s definition of muscle hypertrophy (and related lingo) as well as an overview of how protein builds muscle in the context of exercise and fitness.

What is Hypertrophy? 

Simple Definition of Hypertrophy: The growth/enlarging of tissue or an organ, typically in reference to skeletal muscle. (Ex., cardiac hypertrophy means “growth of the heart.”) 

At its most basic, hypertrophy is the scientific term for “growth.” In this sense, if you put on body fat, that’s technically hypertrophy of fat tissue (adipose). Granted, that’s not the hypertrophy most gym-goers are after. 

The ultimate “meathead” definition of muscle hypertrophy is “makin’ them gainz.” That’s about as concise, dumbed-down, and grammatically improper as it gets. So, when a supplement claims to increase muscle hypertrophy, it’s just a nerdy way of saying it will help you build muscle

In medical and scientific contexts, hypertrophy may refer to undesirable growth of tissue or an organ, such as the liver or heart. The opposite of hypertrophy is atrophy — the shrinking/reduction in size of tissue or an organ.

Thus, muscle atrophy means a loss of muscle mass. Obviously, not many people are purposefully looking to lose their hard-earned muscle tissue. Though, there are plenty of people that would welcome some adipose tissue atrophy (read: body fat reduction).

As you likely know, muscle hypertrophy is stimulated primarily by intense exercise and a protein-rich diet (with plenty of calories). Hence, regular resistance training and ample protein intake are the most effective ways to promote muscle growth. 

Now, where things get a little more complicated is describing the components that drive muscle hypertrophy. (Hopefully, the following makes it comprehensible…)

Metabolism: What Do Anabolic and Catabolic Mean?

Given that the primary fitness goals for many gym-goers, bodybuilders, and athletes alike are to improve their body composition and get stronger, maximizing muscle hypertrophy is critical. To do so, you need to support muscle anabolism and mitigate muscle catabolism as much as possible. 

Again, don’t let technical terms like anabolism and catabolism discourage you — they are just fancy ways to describe metabolic reactions. 

What Makes a Muscle Anabolic or Catabolic?

Metabolism explained

Metabolism is arguably the most misunderstood concept despite its widespread use in fitness subculture to describe thermogenesis and “calorie burning.” Thankfully, you’re about to get a proper definition of metabolism and what it really means for a muscle to be “anabolic.”

Your body is comprised of hundreds of trillions of cells, the simplest “living unit.” Each cell in your body is carrying out reactions to sustain basic biological processes that keep you alive, such as breathing and maintaining a heart beat. 

These cellular reactions are divided into two categories: anabolic and catabolic. Anabolic reactions use energy to create new cellular components and complex molecules. Catabolic reactions are the opposite — they break down complex molecules and cellular components to release energy (and create simple molecules). 

A basic example is the metabolism of glucose (sugar) to form adenosine triphosphate (ATP) — the energetic “currency” of cells — and pyruvate, a simple molecule that enters the Krebs Cycle (aerobic respiration). Numerous variables such as physical stress, nutrient availability, hormonal signaling and energy status affects how rapidly these reactions occur and when they take place.  

Therefore, metabolism broadly refers to the cumulative cascade of anabolic and catabolic reactions going in your cells.

It’s important to note that metabolism is constantly in flux, and that anabolic and catabolic reactions are dynamic, intertwining processes. Very few physiological and biological processes operate like an on-off switch; they are more akin to a dimmer switch. 

So, being in an “anabolic state” doesn’t mean there are absolutely no catabolic reactions going in your body. In any case, muscle protein synthesis is the anabolic reaction that leads to muscle hypertrophy (assuming it’s greater than muscle protein breakdown, a catabolic reaction). 

How Does Protein Build Muscle?

You might be wondering, “How does protein build muscle?”

Protein is the foundation of muscle fiber, being the core class of molecules that control muscle hypertrophy and function. The various proteins found in muscle fibers, such as myoglobin, actin, titin, and myosin, are responsible for both the structural integrity and function of muscle tissue. 

When you stimulate skeletal muscle with vigorous exercise, the fibers in muscle tissue are “torn apart” on a microscopic level. In order to repair and hypertrophy, the body needs protein from the diet.

How does protein build muscle

The amino acids from dietary protein are then used to synthesize new muscle proteins, which are then incorporated into muscle fibers and voila! Your muscles have gone from a catabolic to an anabolic state — more robust and (hopefully) a bit larger than before.

But muscle proteins do quite a bit more than just expand the size of muscle tissue. In fact, the proteins in muscle fibers are integral for contracting and relaxing muscles. The catch is that skeletal muscle fibers and their associated proteins need to receive a stimulus from the nervous system to carry out their actions. 

Similar to when you feel the need to urinate (the bladder sends “background” sensory information to the brain), the central and peripheral nervous systems govern the voluntary and involuntary movement of muscles throughout the body.

This is where the “neuromuscular junction” comes into play. 

The neuro-what, you ask? Don’t fret, it’s just another one of those pesky multisyllable science terms that describes the interface between the nervous system and muscle tissue. The following section breaks it down in easily digestible verbiage.

How Do Muscles Contract?

Think of the neuromuscular junction like the connection between a remote control and your TV. The remote is your brain telling the TV (your muscles) what to do. 

When you’re in the gym curling dumbbells or sprinting on the treadmill, your brain is telling your muscles to contract. In other words, you are voluntarily flexing and extending your skeletal muscles, all of which is controlled by nerves that relay a signal from your brain to the target muscles. 

A muscle fiber and the nerve that innervates (read: connects to) it are referred to as “motor units.” While the physiology of muscle contraction and muscle proteins is quite complex, a relatable analogy of the muscle flexing and extending process is that of a bungee run. 

When you forcefully contract a muscle to lift a weight, myosin (protein) motor units grip onto actin proteins in the muscle to pull tube-like muscle fibers closer together, thus shortening the length of the muscle. Eventually, the force of whatever weight you are lifting comes to a stalemate with the contractile force that your myosin motor units can exert; hence, you reach “muscle failure” and your motor units give up the fight, returning the muscle fibers to their extended position.

Pretty neat, eh? Of course, this all happens in the blink of an eye on a cellular level. Nerve impulses can travel exceptionally fast (i.e., 100+ meters in less than a second).

Why You Need Protein for Muscle Recovery

why we need protein

Knowing the function of muscle proteins gives us a better understanding of how protein builds muscle and influences recovery from exercise. When you subject your muscles to sufficient mechanical tension, as in the case of resistance training, your myosin motor units and their associated actin chains can actually get “popped” completely out of place. 

This process is called “sarcomere popping,” and it plays a role in the phenomenon of delayed-onset muscle soreness (DOMS) after exercise (R). We’ve all experienced that unrelenting soreness in our legs the day after an intense leg workout. Well, you can thank DOMS for that. 

Your body corrects sarcomere popping by using an actin-cutting protein called gelsolin that wraps around the out-of-place actin protein chains (R). New actin proteins are then synthesized by ribosomes (think: “protein factories”) in your muscle cells. The ribosomes read the genetic blueprint, or “instruction manual,” encoded by your messenger RNA.

Intuitively, you need to consume plenty of protein so the ribosomes in your muscle cells have the necessary amino acids to create new muscle proteins, actin being just one of them. 

Unfortunately, it takes time for your ribosomes to translate the genetic instructions of messenger RNA into new muscle proteins. This means muscle recovery and muscle hypertrophy are generally not rapid processes, and genetics play a role in your maximum muscle building potential. It can take several days for DOMS to dissipate, and weeks, months, or even years to build a noticeable amount of new muscle tissue

Does a High-Protein Diet Translate to “Extra” Muscle Growth?

There are a myriad of physiological reasons that muscles don’t grow without bound when the body is replete with essential amino acids. 

First, let’s turn to the century-old theory called Le Chatelier’s principle, or the “Equilibrium Law,” named after the famous French chemist Henry Louis Le Chatelier (R). He noted that when equilibrium is “disturbed” by external changes in a chemical system, the system will respond by shifting chemical concentrations back towards equilibrium. 

In layman’s terms, if you add more of a chemical reactant to a solution, it leads to more products (and vice versa). 

So, what the heck does that have to do with muscle growth

Well, your body is a biological system full of molecules. When we consume a high amount of protein through food and supplements, there is an increase in the concentration of amino acids in the blood. Your cells sense this increase and work to “restore equilibrium” (i.e. homeostasis) by creating a corresponding amount of proteins, thereby reducing the blood levels of amino acids. 

If you put more reactants (amino acids) into the system (your body), more protein (products) are created. Though, Le Chatelier’s principle has some flaws when explaining how biological systems like the human body respond to nutrients and chemicals. Surely, if it applied to us like it does to a flask full of chemicals, we could just gorge on protein and build infinitely large amounts of muscle. 

In practice, this is just not what happens.

Consuming exorbitant amounts of protein will not lead to “extra” muscle growth when compared to a more sensible high-protein diet. There is a point of diminishing returns where your body simply can’t make use of surfeit amino acids to create new protein — a phenomenon known as the “muscle-full effect.”(R

To be fair, Le Chatlier never intended for his principle to apply to biological systems; rather, it describes chemical systems. With us humans, it’s a bit more complex since we are biochemical systems. 

How Protein Builds Muscle: Wrap-Up and Key Takeaway

How does ingesting whey protein, for example, facilitate muscle recovery? Well, it’s quite straightforward — whey protein is a rapidly digesting, complete protein source. It gives your muscle cells all the amino acids they require to synthesize new muscle proteins. 

Obviously, if you don’t supply your ribosomes with amino acids, they won’t have the “building blocks” of proteins that comprise muscle tissue. In fact, if your body is significantly deprived of essential amino acids and energy, it will eventually break down the existing muscle proteins for survival purposes. 

Basically, your muscles become catabolic. For muscle hypertrophy, you want the opposite. 

Now, does this mean “more is better” and you should drink whey protein powder around the clock to stay in an anabolic muscle-building state? Certainly not.

Contrary to what conventional wisdom might suggest, ultra-high-protein diets (e.g., 2+ g of protein/lb body weight) do not lead to more muscle growth than a moderately high protein intake (e.g., 1-1.5 g protein/lb body weight) (R). 

Nonetheless, controlled studies of subjects ingesting varying amounts of protein have shown that Le Chatelier’s Principle typically holds true (up to a certain point): the more protein you consume, the more efficiently your body synthesizes new proteins — such as the muscle proteins discussed earlier (R). 

The salient takeaway message from all this scientific mambo jumbo is don’t skimp on your protein intake! Follow up your workouts with a scoop or two of Transparent Labs Grass-Fed Whey Protein Isolate to support muscle hypertrophy and initiate muscle recovery — your ribosomes will appreciate the gesture.




Elliot Reimers, M.S.(C), CNC
Elliot Reimers, M.S.(C), CNC

Author

Elliot is a NASM Certified Nutrition Coach (CNC) and M.S. candidate in the Molecular Pharmacology and Toxicology program at Michigan State University. After obtaining his B.S. in Biological Sciences from the University of Minnesota in 2013, Elliot began freelance writing and has since written 100s of articles pertaining to nutritional science, dietary supplements, exercise physiology, and health/wellness. As an inveterate “science nerd,” he loves helping people understand how nutrients, supplements, and exercise work on a cellular and molecular level so they can be smarter about what they put in - and do to - their bodies. When he's not busy writing or studying, you can find Elliot pumping iron, hiking the mountains of beautiful Colorado, or playing the piano.



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