We all want to gain muscle and look like Arnold, but how does it work?

Muscle hypertrophy, or muscle growth, is the result of progressive overload, or stress, on the muscle that causes it to grow in volume and density. What many novices may fail to realize, however, is that there are actually two main types of muscle hypertrophy that will affect your goals for training: sarcoplasmic and sarcomere (aka myofibrillar).

Sarcoplasmic hypertrophy is the one we most commonly associate with muscle growth because it results in the increase in volume of the muscle which increases its size (think bodybuilders, like Arnold).

In scientific terms, sarcoplasmic hypertrophy is the increase in the cytoplasm of the muscle as a result of the increase in the ATP producing mitochondria within the muscle (1). However, sarcoplasmic hypertrophy is not associated with increased strength, per se, but rather increased endurance because there is increased glycogen stores that can produce more ATP for energy. Thus, individuals, such as bodybuilders, have lots and lots of muscle, but it doesn’t necessarily mean that they have top tier strength and power relative to their weight and height because of the type of muscle they have.

Image result for sarcomere vs sarcoplasmic hypertrophy


(Notice how in sarcomere hypertrophy the myofibrils become larger, or denser, and the muscle fiber relatively remains the same. In contrast, sarcoplasmic hypertrophy is where the muscle fiber is enlarged because of increased sarcoplasm in the muscle fiber.)

In contrast, sarcomere, or myofibrillar, hypertrophy is the result of the increase in density of the muscle (think power/olympic lifters or fighters) that results in the increase of myofibril size, which allow for greater tension and contraction force that the muscle can produce (1, 3).

Sarcomere hypertrophy is where the muscle is actually broken down and then rebuilt stronger through a complex process involving satellite cells, immunology, growth factors (human growth hormone, fibroblast growth factor, hepatocyte growth factor), testosterone, and other factors to increase the density and subsequent strength of the muscle (2).

As mentioned earlier, olympic lifters and fighters are great examples of sarcomere hypertrophy because they have astounding strength and power for every pound of bodyweight they have as compared to their bodybuilder counterparts. They may not have the “bulk” associated with large muscles, but they have very hard and dense muscles that are superior for athletic performance that allows for speed, power, and brute strength.

This is not to say that the two types of hypertrophy are not related, or correlated, with one another, because they are, but it’s important to understand the difference between the two for your training, so you can achieve what you want for your fitness, athletic, and sporting goals.


For example, think of a linebacker in football. That linebacker is going to do a lot of strength dominant conditioning and programming, so he can be quick enough to chase down a running back while also being strong enough to rip through an offensive lineman. Essentially, he has a lot of Type II, or fast twitch glycolytic, muscle fibers that are associated with sarcomere hypertrophy (2). He trains for his sport specifically and so should you for your fitness and athletic goals.

If you’re having trouble visualizing how your sets and reps should look, reference the diagram below for a visual of what rep ranges to generally train in for your specific objective.


Related image

Follow a program that’s right for you, whether your own or someone else’s, for what you want to achieve (click here for examples). It doesn’t have to neglect one or the other (if it does then that’s a poor program), but usually you’re going to be more dominant in one type of hypertrophy as opposed to the other.

Now, what do you do?

Do you follow a strength program that calls for greater sarcomere hypertrophy, or do you follow the traditional sarcoplasmic hypertrophy program used by bodybuilders. Tell me by leaving a comment down below.

As always, thanks for reading and stopping by. If you’re a subscriber thank you and if not, please subscribe.

Until next time, be strong and be you!


1. Saadat, V. (2011). The Science Behind Exercise. USCience Review. Retrieved from http://www-scf.usc.edu/~uscience/exercise_science.html

2. Hernandez, R. C. The Mystery of Skeletal Muscle Hypertrophy. University of New Mexico. Retrieved from http://www.unm.edu/~lkravitz/Article%20folder/hypertrophy.html

3. DeFranco, J. Why All Muscle Was Not Created Equal. DeFranco’s Training Systems. Retrieved from https://www.defrancostraining.com/articles/38-articles/52-why-all-muscle-was-not-created-equal.html

(Photo Credit 1)

(Photo Credit 2)

(Photo credit 3)


5 thoughts on “The Low Down on Hypertrophy: Sarcoplasmic vs. Sarcomere (aka Myofibrillar)

  1. I dont think this is correct…..hypertrophy is the increase in the size of cells, hyperplasia is the increase in number of cells, you cant actually make create new muslce cells (you dont get hyperplasia). Hypertrophy is exclusively the increase in cell size, not number as you suggested with the above diagrams

    1. You’re right! The myofibrils increase in diameter, or density, which equals increased strength. That diagram is misleading because it suggests new cells are created which is not the case. Thanks for the correction and feedback!

    1. Hey thanks for reading Laurenti!

      Being strong isn’t bad at all (for me that’s my priority). But having the aesthetics of big muscles is definitely nice too and necessary for strength. I’ve found you have to balance both types and you’ll get what you’re looking for.

      Thanks again for the comment!

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