Hypertrophy: Sarcoplasmic vs Myofibrillar

Muscle growth and Sarcoplasmic Versus Myofibrillar Hypertrophy has been debated for a long time. This phenomenon is however not really what most people think it is and the knowledge spread about it is greatly limited.

Since there are many different theories out there which are just making it more confusing, here’s the deal about it.

What is it?

Is an increase in size of an organ or skeletal muscle tissue due to a enlargement in size of its cells. There’s different ways you can increase the volume of muscle cells. These changes is an adaptive response to activities that generate force or resistance to your muscle tissue until momentarily fatigue – like exercise, with its many different kinds and variations.

There are two different ways muscle growth can occur:

Sarcoplasm is the stored glycogen and myoglobin, which are fluids and energy resources, surrounding the myofibrils in your muscles. Sarcoplasmic “hypertrophy” occurs when the volume of sarcoplasmic fluids in your muscle cells increase.

This process basically only adds temporary volume to muscle but not actual fiber growth, which results in a less functional mass and a reduction in relative strength since it would just be adding useless bodyweight.


Myofibrils are mainly composed of long proteins: actin, myosin and titin, these together with a few other proteins, hold them together. This growth is focused on increased myofibril size. Myofibrils are the elongated threads in skeletal muscle fibers which contract.

This growth happens when you stimulate your muscles by lifting heavy weights which is causing trauma to the individual muscle fibers. Your body treats this as an injury and overcompensates in attempts to recover, this increases the volume and density of the traumatized myofibrils. 


Since Sarcoplasmic growth actually isn’t hypertrophy and basically only brings temporary volume and not much else to the table, Myofibrillar hypertrophy is what you actually want to be concentrating on in terms on functionality and physical quality. You achieve this by focusing on lifting very heavy weights and on low (5-10 depending on activity) repetitions that ensure slow, perfect technique. Your larger muscle fibers will increase force, meaning more strength and speed.




Myths about specific training for one or the other


There are many claims that you can specifically train for sarcoplasmic versus myofibrillar hypertrophy, there are however no factual evidence for these claims.

Its likely that the belief of these different training regimens comes from observing the difference in training between bodybuilders and powerlifters and failure to consider the role of genetics and selection bias.

Any quality program performed hard, progressively, and consistently with a reasonable volume and frequency for the individual, will eventually get them as big and strong as their genetics will allow, but the ratio of strength to size gains will vary considerably between individuals.

Some people can simply get incredibly strong without much increase in muscle size and these will tend to gravitate towards strength sports where size to strength ratio is advantageous. Some people are able to gain a lot of size relative to their strength increase, and will tend to gravitate towards bodybuilding where muscularity is an important criteria but relative strength is irrelevant.

Regardless of the training program you follow, your ratio of size to strength gains is dictated by genetics. The amount of myofibrillar protein in skeletal muscle fibre stays the same. There are no examples of where a muscle fibre hypertrophies with resistance training and the myofibrillar cells doesn’t grow but the sarcoplasm does. The occasional example of a dissonance between hypertrophy and strength gain, is not due to a sarcoplasmic hypertrophy due to low-load conditions.

A genetic example: a shorter person have shorter muscle fiber length, which can visibly enhance volume, the ratio might allow them to easier add on muscle volume than a lengthier person, in relation to their physical traits.


Bottom line 

There is actually no such thing as Sarcoplasmic hypertrophy, although there is sarcoplasmic temporary growth – a pumped up muscle.

Myofibrillar hypertrophy is the only growth that is of any functional use. If you’re looking for strength and adding muscle, this is what you want and will achieve as long as your following a proper training program.

Although results will vary individually depending on genetics, proper strength training will build muscle and is something that you should do!


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