Hyperplasia vs. Hypertrophy: Building Muscle

Many people in the fitness domain are well-aware of the term hypertrophy, which refers to an increase in muscle fiber diameter. Quite recently, people have started discussing another process called hyperplasia, which has also become a topic of controversy lately. This term is also linked to muscle growth but in a different manner.

According to several studies, hypertrophy occurs in humans as a result of bodybuilding. On the other hand, the status of hyperplasia remains ambiguous due to an ongoing debate on whether it exists in humans or not. In this article, we are going to discuss the difference between hyperplasia and hypertrophy, so read on.


Hyperplasia vs. Hypertrophy

Muscle hypertrophy, as the name suggests, refers to an increase in the size of muscle cells. It can be achieved by supplying the muscles with water, glycogen, and protein – although fitness trainers and bodybuilders are more interested in a high protein intake to increase muscle mass.

Muscle hyperplasia is referred to as muscle cell formation. According to theory, increasing the number of muscle fibers bulks up the total muscle mass in the same way as increasing the size of each muscle fiber.

While muscle hypertrophy’s effect is proven and well-known in humans, many people claim that muscle hyperplasia is not possible in humans. Those individuals support the notion that any increase in muscle mass is due to the increase in muscle fiber size.


The Research Regarding Hypertrophy vs. Hyperplasia

According to multiple studies, muscle hyperplasia exists in animals like chickens, quails, mice, rabbits, fish, rats, and cats. The reason for the lack of research on humans in this regard is that these studies involve some unusual and, sometimes, cruel protocols, which are simply not applicable to the case of humans. For example:

  • One of the studies to determine the existence of hyperplasia involved attaching a progressively heavier weight to a bird’s wings for about 28 days. This resulted in a 294% increase in the bird’s overall muscle mass due to hyperplasia.
  • Another study involved cutting the rats’ tissues open and then letting those tissues heal.

Based on these studies, it is difficult to conclude anything regarding what causes hyperplasia. And it is even more difficult to see whether this process can be triggered in humans.

That being said, some studies do exist that show the humans’ tendency to have hyperplasia. However, there isn’t much clarity about the methodology of these studies.

For example, some studies show that bodybuilders have a higher number of muscle fibers or cells compared to people who do not exercise regularly. This validates the claim to a certain degree that hyperplasia can be triggered in humans through consistent weightlifting.

The problem, however, with this assumption is that:

  • There is no data regarding the number of muscle cells the bodybuilding participants had before they started training. We cannot rule out the possibility that those people were born with more muscle cells.
  • These studies could only find a correlation between a higher number of muscle cells and overall increased muscle mass. They don’t demonstrate hyperplasia.
  • Most of the studies have found that people who exercise and those who don’t exercise had muscle fibers in the same number. This indicates that bodybuilders have bigger muscles due to the increased size of muscle cells and that they do not develop new cells.

Now the question arises: how did the bodybuilders in some studies manage to develop new muscle cells? This could be due to the use of steroids, as research shows that fitness trainers who use steroids have more muscle cells than those who play by the book.

This may also explain why people who use steroids are more likely to keep their bodybuilding gains years after they stop using steroids.

Based on all these factors, we can assume that hyperplasia would take a long time to occur. And, it contributes only meagerly to the overall muscle size and strength.

What does all this tell us?

It is undeniable that hyperplasia occurs in animals. But the way it occurs depends on the species and the particular protocols used to trigger it.

It is not clear whether hyperplasia can occur in humans. If there were some ways, those could be:

  • Taking steroids (even though we do not know how effective this can be)
  • Being consistent with heavy lifting several hours a day for years (which might cause hyperplasia only by a few percentage points).


Can You Trigger These Processes In Your Body?


The best way to induce hypertrophy in your body is to lift weights. For this:

  • You must allocate most of your gym time to lifting weights that challenge 75-to-85% of your 1RM. It involves training to the point of muscular failure (the point at which you cannot lift weights anymore despite your maximum effort).
  • You must train each muscle group with 10 to 20 sets per week.

Exercising with this intensity increase the levels of a particular enzyme called mammalian target of rapamycin, or mTOR. This enzyme stimulates protein synthesis necessary for hypertrophy. To keep track of the exercises you can use a Vitruve encoder.


Hyperplasia is possible in humans, but it is unclear whether you can trigger it in your body. With that in mind, hyperplasia will probably be a side-effect of lifting weight properly and not a result of special training techniques or diet.

Still, people continue trying to discover training protocols that may help trigger hyperplasia. Since hyperplasia mostly occurs in birds, fitness enthusiasts claim that you can mimic their movements to achieve the desired result.

They usually recommend body stretching between sets and going with high-reps and light weights. These training protocols mimic the movements that cause hyperplasia in birds.

Research suggests that stretching alone may help grow muscles in humans. And several other studies show that performing weighted stretching may raise the levels of anabolic hormones. But none of these studies suggest an occurrence of hyperplasia in humans.




When thinking about hypertrophy vs. hyperplasia, you may wonder which one of these processes you should target when training. Hypertrophy is a well-known process that gets triggered when you lift weights, and its training protocols are well-established, which can be measured with a VBT. On the other hand, whether hyperplasia occurs in humans remains an ambiguity, and the training protocols that supposedly cause hyperplasia are not scientifically validated.

Click to rate this post!
[Total: 0 Average: 0]
Vitruve Team

You may also like…

Notify of
Inline Feedbacks
View all comments