Sarcoplasmic Hypertrophy Vs Myofibrillar Hypertrophy [What You Need To Know]

Daniel Maman April 10, 2013


In the world of bodybuilding, looks can be deceiving.

I am sure you have experienced a scenario similar to this: One day you are working out and you see a huge guy that is ripped out of his mind.

As he goes to squat, you are waiting eagerly for him to start lifting an astronomical amount of weight but notice that he seems to struggle with a weight that is not very heavy.

The next day you go to the gym and notice a man that is kind of chubby and you do not think much of his potential strength, but then notice him squatting almost double the ripped guy you saw at the gym previously. How could this be?

In this article, we go through how the above scenario is possible by exploring how our muscles respond to stress, the difference between myofibrillar and sarcoplasmic hypertrophy, and how to apply this to help you reach your workout goals.

The Reason PowerLifters Can Lift More Than Bodybuilders 

We often see this same scenario when it comes to bodybuilders versus powerlifters.

Often times, powerlifters are much smaller, have much less musculature than bodybuilders, but they can lift much more weight. Why is this?

Power lifter v bodybuilder

One reason for this is simply that some people have better mechanical advantages, such as limb length and insertion, than others. 

Other reasons could be the rate of fast twitch muscle fibers and neural efficiency.

The final reason is the difference in training (sarcoplasmic v myofibrillar hypertrophy) and how that affects strength. 

This is what we will be focusing on in this article. 

What Is Muscular Hypertrophy?

In order for your muscles to gain size, muscular hypertrophy must occur, which in simple terms, means that the individual muscle fibers increase in diameter.

So by working out and overloading your muscles, your muscle cells get bigger, and are thus, experiencing hypertrophy. 

Functional Vs. Non-Functional Strength

I often hear a lot about functional versus non-functional strength in the bodybuilding realm and would just like to clarify on what that really means.

When people refer to “functional” hypertrophy, they are talking about the gains in muscle size that cause improvements in the production of muscle force.

When they are talking about “non-functional” hypertrophy, they are talking about the gains in muscle size that do not cause an increase in the production of force.

Bodybuilding would be so much simpler if this were as simple as many people like to make it, but unfortunately it is not.

Despite the numerous benefits that strength training regimens have on sports, no training regimen is perfect and no workout scheme can be transferred directly to one’s sport.

What Is The Difference Between Sarcoplasmic Hypertrophy And Myofibrillar Hypertrophy?

To understand the different types of hypertrophy, it is important to have a background of the muscle physiology.

The individual protein filaments are called myofibrils and are surrounded by a fluid called the sarcoplasm.

Thus, you have the terms myofibrillar hypertrophy, which is when the myofibrils increase in size, and sarcoplasmic hypertrophy, which is growth of the sarcoplasm. 

Functional hypertrophy training refers to hypertrophy of the myofibrils, while non-functional hypertrophy refers to hypertrophy of the sarcoplasm.

Myofibrillar hypertrophy is associated with training heavy with low reps while sarcoplasmic hypertrophy is associated with training with higher reps and lighter weight.

How Does Sarcoplasmic Hypertrophy Work?

Sarcoplasmic hypertrophy works by increasing the amount of mitochondria in the cell (structures within the cell responsible for energy production).

The reason sarcoplasmic hypertrophy is supposedly responsible for non-functional hypertrophy is because the sarcoplasm consists of non-contractile fluid and thus, can gain size without any strength increase.

The pump you feel during a great workout is a result of the sarcoplasm expanding. 

It is believed that training for sarcoplasmic hypertrophy creates big muscles that are not functional, or muscles that are simply for appearance.  

There are some reason benefits  of sarcoplasmic hypertrophy that don’t include frat bros growing their ego from flexing at the gym after a great pump.

Two of those include:

  1. Increases in endurance due to hypertrophy of the mitochondria
  2. Increase in connective tissue growth

physiology of muscle fiber

How Does Myofibrillar Hypertrophy Work?

A myofibrillar hypertrophy workout, on the other hand, works by increasing the amount of actin/myosin filaments within the cell.

This leads to increased strength and size of the contractile unit of the cell resulting in a greater production of force.

This is often referred to as functional muscle because of the increase in force production.

(Aka, you can lift more.)

Why glycogen stores are important

A big reason for an increase in size caused by sarcoplasmic hypertrophy workouts is the increase in glycogen stores.

Glycogen stores are simply stored energy which is needed for high volume workouts.  

When one constantly works out with high volumes of repetitions, the body stores more glycogen in response. With every gram of glycogen storage, 3 grams of water comes with it.

This extra glycogen and water storage can create a considerable amount of size increase and will allow you to lift for longer periods of time because of the increase is energy.

However, it will not result in increased strength or power.

For example, on average, the typical male can store approximately 350-500 grams of total glycogen in the muscles of his body.  

If this person starts to workout at high volumes, he can achieve almost 1000 grams of glycogen storage which would be an additional 1500 grams of water (an increase of 500 grams of glycogen multiplied by 3).

This can create an increase of almost 5 pounds of what would appear to be solid muscle mass when in reality it is simply energy stores and water.

Five pounds of “muscle” may not sound like much, but it can make a considerable difference in appearance.

If you were to take an individual who consistently performed low volume workouts, his stores of energy would not be very high.

If you were to then have him start performing high volume workouts you would see an increase in the size of his arms as his body would adapt to the increased amount of work by storing more energy.

Although he would still be increasing his myofibril strength with the higher rep range, he would not be as efficient in his force production.

Although different rep schemes stimulate different growth, they cannot be separated entirely.

Even when you perform rep ranges focused on sarcoplasmic hypertrophy, you will still cause some myofibrillar hypertrophy, and vice versa.

The reason for this is that the size of the sarcoplasm is limited by the size of the myofibril within it.

Many studies have attempted to show that myofibrillar hypertrophy and sarcoplasmic hypertrophy occur independently of one another but have all failed to do so.

The studies have shown that it is not possible to increase sarcoplasmic growth without the presence of accompanying myofibril growth.

So why does this cause some people to look “weak” for their size?

This could be for many reasons.

For one, those that consistently lift higher rep amounts will not lift maximal weight very often and thus will not be skilled enough to lift maximal weights.

And yes, lifting maximally is a skill.

This goes both ways, however.

Although it would most likely be difficult for a bodybuilder who consistently trains with high reps to match the powerlifter on maximal low rep sets, it may also be difficult for the power lifter to match the bodybuilder on multiple high rep sets.

Should You Focus On Myofibrillar Hypertrophy or Sarcoplasmic Hypertrophy?

As we discussed, you will always be working both when lifting. The choice is lies in which you want to emphasize, which is based on your goals.

If you want to increase strength and lift maximal weights and/or improve performance for a sport that benefits from an increase in strength, then sticking to myofibrillar hypertrophy is the way to go. 

If you care less about increasing strength, and want to get as big as possible, and your goal is purely aesthetic, then sarcoplasmic hypertrophy is your best bet. 

And of course, you can always include both in your workout regimen to ensure your hitting your muscles in different ways to prevent plateaus. 

What Are The Rep Ranges For Sarcoplasmic Hypertrophy & Myofibrillar Hypertrophy?

To focus more on myofibrillar hypertrophy, focus on the 3-8 rep range.

To hit more on sarcoplasmic hypertrophy, sets in the 8-15 range are ideal.


  1. Muscular adaptations in response to three different resistance-training regimens: specificity of repetition maximum training zones.Eur J Appl Physiol. 2002 Nov;88(1-2):50-60. Epub 2002 Aug 15.
  2. Protein synthesis rates in human muscles: neither anatomical location nor fibre-type composition are major determinants. J Physiol. 2005 Feb 15;563(Pt 1):203-11. Epub 2004 Dec 20.
  3. Starr, Robert L. “What Makes Muscles Grow?” Bodybuilding.
  4. Butt, Casey. “Muscle Growth Part I: Why, And How, Does A Muscle Grow And Get Stronger?” The WeighTrainer. 2007.
  5. Hernandez, Richard J, and Len Kravitz. “The Mystery of Skeletal Muscle Hypertrophy.”

Daniel Maman

Daniel Maman's two biggest passions in life are health and fitness. He is a certified personal trainer, has a degree in exercise science, and spends his free time keeping up to date with the latest research. In his free time, you can find him playing basketball, bouldering, and spoiling his dog, Luna.

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