Skeletal Muscle Growth: Hypertrophy vs Hyperplasia

Skeletal Muscle Growth- Hypertrophy vs Hyperplasia
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If you are a “muscle head” or simply someone keen on working out and building the perfect physique (which often translates to excellently defined muscles and cardiovascular fitness), then you have probably had many theories about how you can achieve this end.

The very first thing you will probably hear from fitness enthusiasts is that to gain a muscular body, you need to do exercises that increase the size of your muscle fibers. That’s why you are advised to gradually but steadily increase your weights when weightlifting or resistance when doing bodyweight training exercises.

This is referred to as muscle hypertrophy – the increase of size in muscle fibers.

However, another theory, albeit more controversial, will probably come up the more entrenched you become in this “gym-going world.” Muscle hyperplasia.

This is has become a rather hot topic in exercise physiology circles as people debate whether or not it’s possible to actually increase the number of muscle fibers – which is what muscle hyperplasia is (the increase in the number of muscle fibers) as well as the size of the muscle fibers (hypertrophy) in your body.

You can see why this would be something rather controversial. After all, if you can increase the number and size of muscle fibers in your body, it’s conceivable that you can quite possibly get to be as big as you want to be with the right kind of exercise.

Let’s take a look at the raging debate on hypertrophy vs hyperplasia and try to make sense of it all.

Note: Muscle Hypertrophy is the increase in muscle fibers, and muscle hyperplasia is the increase in the number of muscle fibers. Also, muscle fibers are synonymous with muscle cells. These are terminologies that will be used throughout this article.

Is Muscle Hyperplasia a Myth?

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Let’s start with answering the burning question: is muscle hyperplasia a myth?

The simple answer is – No, muscle hyperplasia is not a myth. It’s a phenomenon that has actually been studied. However, when it comes to human physiology, the answer is almost never as simple as that!

To understand muscle hyperplasia, it’s best to take a look at how human skeletal muscles are built.

For the longest time, it was believed that the best and only way to build muscle was to cause it some kind of trauma, through something like exercising by lifting weights and pushing your muscles to create more force than they do on any normal day-to-day activity. In response to this sustained trauma, your muscles will find a way to adapt, i.e., grow, get bigger, and stronger. That’s how people have always built muscle – through muscle hypertrophy.

To make it simpler, some physiologists have looked at this as merely the result of the exercising party adding more protein components to what is already existing muscle fiber. You are adding more bricks to an already constructed wall, thus making it thicker and stronger.

However, there have been studies, mostly on animals such as birds, where scientists have documented evidence of increased muscle cells or fibers.

Hyperplasia is theorized to occur through two main mechanisms:

  • With enough trauma (weight load), your existing muscle fibers can split into smaller fibers, increasing the number of muscle fibers in your body.
  • Whenever your muscles experience enough trauma, there are specialized cells which are called satellite cells, are activated. These cells can eventually fuse into one another and form new muscle fibers.

Studies have been conducted into this area. However, those studies were of animals such as birds with tiny weights tied to their wings for 30 days. The studies found that not only were the birds’ wings stronger, but the number of muscle fibers in those wings was more.

Now, here is where the controversy comes into play. Human beings aren’t birds, nor can you force anyone (you will be hard-pressed to find volunteers) to walk around doing dumbbell curls for a sustained period.

For researchers to empirically determine whether or not the number of muscle fibers had increased, they would have to take a cross-section of the subject’s muscles and study them in a lab. Do you know anyone who would volunteer for that? Very doubtful. You can see why evidence of muscle hyperplasia in humans can be challenging to come by.

However, some groups have tried.

In a study that put high-level bodybuilders against sedentary counterparts, it was discovered that bodybuilders had significantly more muscle fibers than their counterparts.

The problem here is that researchers can’t be sure that this difference in the number of muscle fibers came about as a result of their continuous weight training or it was merely thanks to the fact that professional bodybuilders are just more genetically predisposed to building bigger muscles and a natural cheat code for such people is simply a higher baseline number of muscle fibers.

Kind of like how most NBA professionals are just naturally taller individuals.

Researchers concluded that hyperplasia was probably responsible for the difference in muscle size (bigger arms and quadriceps in sprinters). This is after a microscopic study of the muscles found no real difference in size compared to those of the sedentary individuals.

As such, it can be concluded that the visible difference in muscle appearance must be thanks to the fact that these professionals had somehow built more muscle fibers…. or just naturally had them to begin with.


Hyperplasia probably occurs in humans, too but to what extent, scientists can’t conclusively answer. What we do know for a fact is that muscle hypertrophy does occur, and it’s probably more responsible for skeletal muscle growth than hyperplasia. So, the controversy rages on.

Muscular Woman

What You Need to Know About Muscle Hypertrophy

Probably the most straightforward explanation for muscle growth is muscle hypertrophy. This is basically when your muscles grow in size due to continuous and sustained training sessions such as weight lifting. This increase in muscle mass can occur in two ways:

  • Myofibrillar – which is the increase in myofibrils that leads to stronger muscles. Simply put, your skeletal muscles connect to your bones through tendons which aid in your day-to-day movement. There are bundles of muscle fibers called myocytes that make up your skeletal muscles. Each one of these myocytes contains myofibrils which are how they contract. When you train for myofibrillar hypertrophy, you increase the myofibrils’ strength and density, thus making you stronger.
  • Sarcoplasmic – which is the increase in glycogen storage that leads to bigger muscles. Sarcoplasmic hypertrophy occurs when the sarcoplasmic fluid is the fluid resource surrounding myofibrils in your muscles. This fluid contains glycogen, triphosphate, water, and creatine phosphate. Whenever you work out, more of this fluid moves to your muscles and provides you with energy. Sarcoplasmic hypertrophy is this increase in fluid volume that occurs when you work out. As such, it can make your muscles appear bigger but not necessarily stronger.

How Can You Achieve Muscular Hypertrophy?

The huge assumption here is that you are reading this piece because you want to find ways to increase your muscle mass and wonder whether achieving muscle hyperplasia or hypertrophy was better.

All things constant; it’s achieving muscle hypertrophy that we can quantify and do. This is going to be a rundown on how you can successfully build skeletal muscle mass. Here are some tips that should help:

Work Out

This might seem obvious, but it needs to be said: to build muscle, you have to subject your existing muscle fibers to intensive trauma – which involves lifting weights and working out in general.

Whenever you lift heavy weights, there are contractile proteins in your muscles that generate force, hopefully enough to overturn the resistance caused by the weight being lifted.

If the weight is heavier than what that particular muscle is used to sustaining, then the muscle will sustain some structural damage in its effort to overturn the resistance. When this mechanical damage happens to the muscle, the muscle’s proteins kick into action and begin repairing the damage. This entire process results in bigger muscle fibers.

For more muscle gain, you need to achieve something called metabolic fatigue, which is when your muscle fibers use up all the available ATP. This energy component effectively helps your muscles contract.

When this happens, your muscles won’t contract, and as a result, you can’t lift the weight in the correct form. This is what you will typically hear being called “training to muscle failure.” Training to this point leads to muscle gain. If you are going to achieve muscle hypertrophy, you must achieve mechanical damage and metabolic fatigue.

However, achieving muscle hypertrophy correctly is not all about lifting weights, although that is a huge part of pushing your muscles and providing the necessary trauma to make them grow.

Boiled Eggs and Tomatoes

Eat A Lot of Proteins

If you are going to build muscle sustainably, you need to eat a lot of protein. There is an exact science to this madness – you should look to eat about 1g of protein for every 454g of your body weight.

This means that if you weigh about 91kg (200 pounds), you should look to consume about 200g of proteins per day. Thankfully, achieving this isn’t as complicated as it sounds. All you have to do is eat a proper whole protein source with every meal.

This often includes:

  • Red meat such as beef and lamb
  • Poultry such as chicken, duck, and turkey
  • Fish such as salmon, sardines, tuna, and mackerel
  • Eggs
  • Dairies such as milk, cottage cheese, and yogurt

Rest Up

One of the biggest mistakes most people make, especially newbies who are just getting into weight training, is to go hard without resting. It’s easy to get sucked into the euphoria, especially once you start feeling those initial gains.

The problem with weight training without giving yourself time to rest is that you are not giving your body time to heal and achieve muscle recovery and growth. All this occurs when you are sleeping and not working out. You need to remember to take enough time to rest in between the workout days.

Focus on Multi-Joint Movements

When was the last time you went to the gym? What are the chances that you do more bicep curls than anything else? You don’t need to be embarrassed if you are in this group of weightlifters; it’s natural to focus on the workouts that present you with the most visible and immediate gains.

Unfortunately, as much value as isolation training has on your physique and appearance, if you want to challenge your body and encourage massive muscle mass gains, you need to focus on multi-joint movements.

These are exercises that challenge many muscles and joints at a go. A good example is the dumbbell row – with every single rep, you are challenging your lats, abs, and biceps at the same time. Thanks to the fact that you are using more muscles in concert with one another, you can lift more weight which means that you can push them further towards metabolic fatigue and growth.

Finally, it all comes down to your diet. You not only need to eat more proteins to build and restore your muscles, but you also need to eat more carbs after each workout session. This will increase your insulin levels, which will slow down the rate of protein breakdown.

As far as hypertrophy vs hyperplasia goes, there is evidence that hyperplasia might actually occur in humans; we just don’t know to what extent. We know that skeletal muscular hypertrophy is something that we can achieve with the above tips.