Sarcoplasmic Hypertrophy Workout Versus Myofibril Hypertrophy Workout

by admin on 8:42 PM

Often times, looks can be deceiving. For example, 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?


Power lifters v bodybuilders

We often see this same scenario when it comes to bodybuilders versus power lifters. Often times, power lifters are much smaller, have much less musculature than bodybuilders, but they can lift much more weight. Why is this? power lifter Sarcoplasmic Hypertrophy Workout Versus Myofibril Hypertrophy Workout

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. Although all these different factors affect strength, this article will focus on sarcoplasmic and myofibrillar hypertrophy.

Sarcoplasmic v Myofibrillar 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. 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 and 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. bodybuilder sarcoplasmic hypertrophy Sarcoplasmic Hypertrophy Workout Versus Myofibril Hypertrophy Workout

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 regiments 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 myofibril 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. Functional hypertrophy refers to hypertrophy of the myofibrils while non-functional hypertrophy refers to hypertrophy of the sarcoplasm. The common belief is that training with a certain amount of reps works one of these mechanisms over the other.

Functional hypertrophy is associated with training heavy with low reps while sarcoplasmic hypertrophy is associated with training with higher reps and lighter weight. 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. It does, however, increase endurance due to the hypertrophy of mitochondria and causes growth of the connective tissue. It is believed that training for sarcoplasmic hypertrophy creates big muscles that are not functional, or muscles that are simply for appearance.  muscle fiber sarcoplasm and myofibrils Sarcoplasmic Hypertrophy Workout Versus Myofibril Hypertrophy Workout

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.

A big reason for an increase in size caused by sarcoplasmic hypertrophy workouts are 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 come 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 times 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 myofibrillar 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. 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 myofibrillar 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.

So what is the real value of rep range?

Although there are beliefs that rep ranges in the weight room can be functional or non-functional, the reality is that functionality is determined outside of the weight room. Yes, lifting weights and getting stronger can help quite a bit in athletics, activities of daily living, etc, but if you want to become functional at a certain task, you have to actually practice that movement to increase functionality. Think of it as a combination. If you train hard in the weight room, consistently practice the activity or sport, and consistently stay active, you will be very functional regardless of the rep scheme you use.  What it comes down to is progressive resistance. If you constantly increase resistance and progress in your workout regimen, you will become more functional regardless of your rep scheme.

If your main goal is to increase your strength then sticking to lower rep ranges is ideal and if your main goal is to look bigger and increase muscular endurance, than the higher rep ranges would be best. Size and strength are correlated so one cannot be improved completely separate of the other. When choosing a workout scheme, figure out what your goals are before determining the types of workouts to perform. What is functional for you may not be functional for another individual.

To focus on more on myofibril hypertrophy, focus on the 3-8 rep range and to focus more on sarcoplasmic hypertrophy, focus more on the 8-15 range. Make sure to use slow and controlled movements on the way down (eccentric portion of lift) and explode on the way up.


Tips for working out

Also, when lifting for hypertrophy, whether it be myofibrillar or sarcoplasmic hypertrophy, make sure that you are pushing yourself to the max and going to failure in at least 1 set per exercise (on the sets you do not go all the way until failure, you should be lifting to 1 or 2 reps away from failure). Make sure that you also lift maximally on ever repetition. So no matter how easy or how hard the rep is, try and lift as powerfully as you can to cause recruitment of all your muscle fibers during each repetition.

Importance of nutrition

And lastly, nutrition is key. Make sure you are eating correctly to allow for maximal gains. If you want to gain muscle you have to create a surplus of calories. Simply figure out your bmr via online bmr calculators and your calories burned throughout the day, and then add 500 calories to that and that is how many calories you should be consuming every day to allow for optimal muscle growth.

One thing I did not really cover which I will cover in next week’s article is the role of nervous system adaptations that allow for motor unit recruitment. When you lift with lower rep sets, it allows for increased motor unit recruitment because you are working the nervous system’s ability to recruit more motor units. When we lift we do not recruit all of our muscle fibers so in essence we could lift a lot more with the same amount of muscle. So by lifting very heavy weights with low reps you will get stronger without gaining size. I will go more into detail in next week’s article though.


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.

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.

Starr, Robert L. “What Makes Muscles Grow?” Bodybuilding.

Butt, Casey. “Muscle Growth Part I: Why, And How, Does A Muscle Grow And Get Stronger?” The WeighTrainer. 2007.

Hernandez, Richard J, and Len Kravitz. “The Mystery of Skeletal Muscle Hypertrophy.”

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