What Is Hypertrophy?

The term used to describe the increase in muscle size associated with muscle growth. There is research that suggests there are in fact two types of muscle growth:

Sarcoplasmic Hypertrophy

Sarcoplasmic muscle growth refers to muscle growth through an increase in the volume of the non-contractile muscle cell fluid (sarcoplasm). This means that whilst the size of the muscle increases through training there is no increase in muscular strength due to an increase in the cross-sectional area but a decrease in density of muscle fibres.

This type of muscle growth is associated with a swelling of the muscles as the number of fluid increases and is usually described as “bodybuilder” training; higher reps with light to moderate load.

Myofibrillar Hypertrophy

On the other hand, myofibrillar muscle growth refers to an actual increase in the number and size of muscle fibres. This enlargement of the muscle is caused by an increase in myofibrils which in turn allow the muscle to produce a greater amount of force.

This muscle growth is associated with a denser looking muscle sported by, for example, gymnasts and other athletes with good aesthetics and a high level of relative strength who train using moderate reps and moderate to high load.

Are There Actually 2 Types Of Muscle Growth?

There is a lot of debate about the validity of sarcoplasmic muscle growth and whether it exists or not.

Sarcoplasmic muscle growth has research on both sides of the fence and appears to have come to the forefront as an explanation for the discrepancy in strength between bodybuilders and weightlifters, i.e. why a 200 something lb bodybuilder can get out-lifted by 100 something lb weightlifter.

The idea is that bodybuilders have ‘non-functional’ sarcoplasmic muscle growth which allows them to get bigger but not stronger.

This leads people to argue that if you want to be strong with dense muscles you should train using moderate reps and high load to create myofibrillar hypertrophy and if you want size irrespective of strength then you should use high reps with a light to moderate load.

However, there are other reasons for this difference in strength between bodybuilders and powerlifters.

Namely, the skill component of lifting, for instance, if you lift very heavy loads when squatting frequently, then you’ll get better at doing exactly that. It’s no secret that bodybuilders lift differently with a focus on volume and not strength which helps to explain this difference in muscle size and relative strength.

Whichever way you look at it there are arguments and research for and against the existent of sarcoplasmic hypertrophy, see 'useful resources' for more on this.

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