Muscle Fibers- Part 2

In part 1 we discussed myofibrils, and mitochondria - two important components that make up muscle cell fiber. 

Myofibrils call for strength & performance of work, and mitochondria are the powerhouses.

You have three muscle fiber types; the white fast twitch, the red fast twitch, and the red slow twitch muscle fibers.  What makes them different is their varying number and size of the myofibrils  and mitochondria.

In the white fast twitch muscle fibers we have the greatest number and size of myofibrils. And there are more myofibrils in the red fast twitch then in the red slow twitch (but not AS many as the white fast twitch).
Got it? 
So white fast twitch are the strongest THEN red fast twitch, and then red slow twitch.

The white fast twitch muscle fibers have the fewest mitochondrial elements, restricting the duration of its contractions. The red fast twitch have more mitochondrial elements then the white fast twitch,  meaning it can contract for longer periods prior to failing.  And finally, the red slow twitch  have the greatest amount of  of mitochondrial elements. They can sustain contractions for much long periods then the other two muscle fiber types!

Human muscle contain a genetically determined mixture of both slow & fast fiber types. The red slow twitch are called slow because they are more efficient at using oxygen to generate fuel (known as ATP), for continuous extended contractions over a long time. They take longer to fatigue then the fast twitch fibers.
The slow twitch fibers  are what is needed to run a marathon, jump rope, bicycle, or do other physical activities for an extended period of time! 

And back to the fast twitch fibers- they are much better at generating short bursts of strength or speed. They use anaerobic metabolism to create fuel. Although much stronger and powerful (the fire up rapidly), they fatigue quickly. Having fast twitch fibers are an asset to someone who quickly wants to generate lots of force, like a sumo wrestler taking down his opponent!

So there you have it! Part 1 and Part 2 of the endless information to be had on the Amazingness going on inside your body!!

Sources: 

www.brittanica.com http://www.britannica.com/EBchecked/topic/377106/messenger-RNA-mRNA

www.sportsmedicine.about.com
http://sportsmedicine.about.com/od/anatomyandphysiology/a/MuscleFiberType.htm

NFPT.com
Personal Fitness Trainer. Certification Preparation Manual. Fundamental Theory and Practical Application for the Personal Trainer. VOLUME ONE.

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