The Two Types Of Muscle Growth


Becoming bigger, stronger and better-looking is one of the primary goals of many individuals that decide to take on weight training.

And while training may seem pretty straightforward, there are actually many different types of adaptations that can occur.

All the functional ones however, are dependent on the adaptations that happen in the muscles!

So let’s have a look at the two types of muscle growth and help you find out which style of training would therefore be suitable for your goals.

But First…

Muscle Fiber Types

Depending on the activity you are doing throughout your training sessions, you can activate different muscle fibres.

Generally speaking, there are two of them:

  1. Fast-twitch muscle fibres
  2. Slow-twitch muscle fibres

You only activate the slow-twitch muscle fibres at low-intensity levels (i.e. jogging or using a light dumbbell).

Those fibres are fit for low-intensity work long in duration and are not really great at producing force and power, so think of these as your ‘endurance muscle fibres.

The more your training intensity grows, the more fast-twitch muscle fibres you recruit to endure the load.

These fast-twitch muscle fibres were designed for high-intensity performance – Short, explosive bursts of power.

Think of the fast-twitch muscle fibres as the fibres you want to engage when building muscle because these fibres have the greatest potential for growth and power output.

But Is It Just The Fibers That Grow?

As we mentioned, training may seem pretty simple at first – You lift heavy weights consistently and, well… You grow bigger and stronger.

However, you can get big in different ways because different training styles lead to different types of muscle growth.

It is considered that there are two main types of muscle hypertrophy:

  1. Myofibrillar hypertrophy
  2. Sarcoplasmic hypertrophy

Let’s have a look at each one individually.

Myofibrillar hypertrophy increases the size of the muscle contractile units, called ‘myofibrils’ and is commonly known as “muscle fibres”.

These muscle fibres are the contractile elements of the trained muscle groups, which allow contraction and relaxation.

On the other hand, Sarcoplasmic hypertrophy is the growth of the ‘sarcoplasm’, which is basically a jelly-like fluid that surrounds the muscle fibres.

The sarcoplasm contains different non-contractile elements, which can grow in volume, depending on the type of training.

So What Training Triggers Either?

It appears that the myofibrils are more closely related to the maximum output of strength and explosiveness, while their sarcoplasm is engaged during intense yet longer loads.

In other words, myofibrillar hypertrophy results from a powerlifting approach to weight training, where you do 1-5 repetitions.

Oppositely, sarcoplasmic hypertrophy results from a bodybuilding approach to training, where you do 6-15+ repetitions with heavyweights.

Now, of course, these are not mutually exclusive!

Though myofibrillar hypertrophy primarily results in increased maximum and relative strength, you have those adaptations with the other type of hypertrophy too, BUT… They are not as prominent.

Take-Home Message

Our musculature appears to be flexible, having the chance to adapt for short, very intense training bouts or medium intensity, prolonged bouts.

This is possible because of the nervous system, our wonderful muscle fibres and their energy reserves!

Whatever your goal may be, try to stimulate both types of muscle growth and other functions like balance, agility, coordination, etcetera.

Become a functional human being!

Stay Strong

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