Fast and slow twitch - twitch do you have more of?

Wondered why you are better at sprinting, or have a good predisposition for explosive bursts of energy?  Or, perhaps you can go on and on, at a steady pace for a long time.  Maybe you have a good ability for both?  On the whole, this is due to the combination of fast and slow twitch fibres that your muscles have. 

 

There are three types of skeletal muscle tissue:

• Red slow-twitch fibres

• White fast-twitch fibres

• Intermediate fast-twitch fibres

These three types of muscle fibres are all present in muscle tissue, to differing proportions, and this is what gives them a range of resistance and contractile speeds. 

The fast twitch fibres are wider and can generate great force rapidly.  They are white because they have less myoglobin (the oxygen carrier within muscle tissue).  They also have less mitochondria (known as cellular power plants, because they generate a chemical that is used as a source of enegy).  These fast twitch fibres work anaerobically and have low resistance to fatigue.  This type of muscle tissue contains lots of glycogen.  They produce quick and large contractions.  Successful sprinters have many fast twitch muscle fibres.

 

Slow twitch fibres rely upon the aerobic metabolism.  They are smaller in diameter, have lots of mitochondria, a dense network of capillaries and are high in myoglobin.  As a result of the myoglobin content, they are very red in colour.  This type of fibre contracts slowly and has a good resistance to fatigue, making them useful for long duration and low intensity work.  Endurance athletes and long distance runners, including marathon runners, have plenty of these. 

 

The intermediate fibres fit pretty much in between the fast and the slow fibres.  They are of medium width diameter.  They contract fairly rapidly and are resistant to fatigue – but not as much as the slow twitch fibres.  Middle distance runners and medium endurance athletes have a fair proportion of these.

Fast or Slow twitch?

 

Inheritance is the key here.  You can increase the size of the muscle fibres through training, but you cannot increase the number of muscle fibres present.  The effectiveness of the muscle fibres that you have can be developed to improve their performance in terms of strength, endurance and size.  You will find that elite athletes tend to specialise in the events/activities that their predominant fibres are best suited to.

 

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If you would like help developing the muscle fibres you inherited, it is imperative to find a good coach/mentor.

 

If there is any other sports topic you would like me to cover, or you have any other questions please contact me at evacyprus@me.com

 

Good bye for now from your dedicated Sports Massage Therapist, Eva Evangelou