Understanding Fast Twitch Muscle Fibers

in Muscle

Essentially, muscle tissues have three distinct fibers as their constituents. Muscles are ideally grouped into two different categories. The first category is for the fast twitch muscles and the second one for the slow twitch muscle fibers. In the category of fast twitch muscles, we classify them further into the type A and type B fast twitch muscles, based still on the speed and engagement ability and also the duration they can sustain engagement.

As such when classifying muscle fibers, it is common to state that we have there types of muscle fibers and in our case we will consider the fastest of them all. The fastest type of fibers in muscle tissues is called the type A, fast twitch muscle fibers. These muscle fibers are solely responsible of forceful contractions that the muscles generate. For those sudden and fast movements you make inside or outside the gym, so fast that the larger muscle has no time to warm and produce the energy needed, it is the fast twitch muscle fibers that rise up to the occasion.

Their speed of activation is as fast as the undiscovered computer processor. Their main weakness though, is that they attain fatigue very fast due to their minimal oxidation ability. So, though they adequately provide for emergency sudden movements, they can not sustain long activities. A good example of this is the sprint. To sprint a hundred meters at top speed and ability, the muscle fibers that are going to be engaged are predominantly the fast twitch type A muscle fibers. Similarly, they are predominantly the fibers engaged when you are performing an all out set of three reps during a weight training exercise.

They tend to have very large motor neurons and very low mitochondrial density. They also have a low oxidative capacity, meaning they will not be able to utilize oxygen very well. It is for this reason that they are not suited to endurance type of activities, because during these exercise variations, oxygen must be present in order to sustain the muscular contractions.

Due to the speed with which these muscles are engaged and the speed of their contractions during the engagement, they have no time to break down nutrients for energy. Actually they feature a near zero oxidation ability. As such, the main fuel that drives these muscle fibers is and must be readily available in a usable form at all times in the body. While slow twitch fibers can weight for oxidation, given that they are slow to engage and have therefore maximum oxidation ability, the fast twitch fibers, especially type A, must be provided with ready-made energy type. They therefore rely on the creatine phosphate and the stored amounts of muscle glycogen, also called glucose.

They can never utilize the stored body fat since they are only engaged in contractions that last for between one and 20 seconds in duration. To train them therefore, they need fast action for brief periods, with maximal intensity levels.

Author Box
Dane C. Fletcher has 1 articles online

Dane Fletcher is the world's most prolific bodybuilding and fitness expert and is currently the executive editor for BodybuildingToday.com. If you are looking for more bodybuilding tips or information on weight training, or supplementation, please visit http://www.BodybuildingToday.com, the bodybuilding and fitness authority site with hundreds of articles available FREE to help you meet your goals.

Add New Comment

Understanding Fast Twitch Muscle Fibers

Log in or Create Account to post a comment.
Security Code: Captcha Image Change Image
This article was published on 2010/03/26