Types of Muscle Fibers and Training

Did you know that muscle has 3 main types of muscle fibers and they play different roles during muscle activity?

Well, if you didn’t know about it, don’t worry!

Because today’s topic is on the types of muscle fibers and training.

Let’s learn about them together!!!

Types of Muscle Fibers

As a known fact muscle is made of thousands of muscle fibers.

These fibers include 3 main kinds:

  • fast twitch muscle fiber (type b)
    white coloured, high in power and  low in endurance
  • intermediate muscle fiber (type IIa)
    pink coloured, high in power and medium in endurance
  • slow twitch muscle fiber (type I)
    red coloured, low in 
    power and high in endurance

Type b is the one that gets big in volume, thus we can say that all the big muscles that we can see from the outside contain higher percentage of type b.

And the reason why type I is red coloured is because it contains more Myoglobin, protein that is essential for metabolisation using oxygen, and it has a red colour.

When we do weight training more Type b muscle fibers get mobilised, which leads to an increment in volume.

On the other hand, when we do aerobic exercise more type I muscle fibers get mobilised.

Transition of Muscle Fiber Type

The percentage of the types of muscle fibers that are contained in the muscle varies depends on the individuals and parts of the body.

But there is an interesting fact. It is said that trainings can make the transition of muscle fiber type to happen. 

This transition happens more for 

type b → type IIa → type I  (especially for  type b → type IIa)

and does not really happen the other way around.

This means that depends on the training you can increase the proportion of muscle fibers that are more suitable for supplying long-lasting energy.

Body Builders have higher percentage of type I???

Body builders train lifting heavy weight, which makes us believe that they would have higher percentage of type b than any other athletes, but in fact it is the opposite.

This can be explained by the way they train. 

Body builders usually lift heavy weights for 5 to 15 times in one set, and they repeat this until their limit.

This huge pressure makes the muscle cells unable to take the oxygen, and this situation lasts for a long period of time.

The muscle cells will try to use the little amount of muscle they can get more effectively,

and this causes the muscle fibers to transit to  type I.

I am training to gain muscle strength, not the durability. 

How should I train taking the advantage of those muscle fiber types?

It is said that when there is the same pressure to the muscle for more than 3 months,

the muscle will start adopting to the pressure.


Changing the training content every 3 weeks will help preventing the muscle type transition to happen.





xxxx FitNessEmikoNess


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