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Type II [[muscle fiber]] is also known as fast twitch muscle fiber. Muscle fiber types can be broken down into two main types: [[slow twitch]] ([[Type I Muscle Fiber|Type I]]) muscle fibers and fast twitch (Type II) muscle fibers.<ref name=Quinn>{{cite web
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its all a lie there not even sqaure
  
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|title=Fast and Slow Twitch Muscle Fibers
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|url=http://sportsmedicine.about.com/od/anatomyandphysiology/a/MuscleFiberType.htm
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|date=October 30, 2007
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|author=Elizabeth Quinn
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|publisher=About.com
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|accessdate=2008-05-13
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}}</ref> These fast twitch fibers can be further categorized into Type IIa and Type IIb fibers,<ref name=Quinn/> which are also known as "fast twitch oxidative" and "fast twitch glycolytic," respectively. Type I fibers are characterized by low force/power/speed production and high endurance, Type IIB fibers are characterized by high force/power/speed production and low endurance, while Type IIA fall in between the two.<ref name=Baggett>{{cite web
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|title=Understanding Muscle Fiber Types
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|url=http://www.bodybuilding.com/fun/kelly13.htm
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|date=n.d.
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|author=Baggett, Kelly
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|publisher=Bodybuilding.com
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|accessdate=2008-10-17
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}}</ref>
   
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It is possible that a fiber might be transformed from Type IIB to Type IIAB to Type IIA with exercise training.<ref name=UOregon>{{cite web
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|title=Muscle Physiology
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|url=http://www.uoregon.edu/~j15/mp/mp_index.htm
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|date=n.d.
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|author=University of Oregon
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|publisher=UOregon.edu
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|accessdate=2008-05-13
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}}</ref> Furthermore, researchers at Boston University School of Medicine have found that increasing the mass or size of type II muscle fibers will lead to a significant decrease in fat mass or the amount of fat in the body.<ref name=NickH>{{cite web
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|title=Type I Vs Type II Muscle Fibers and Weight Lifting Programs
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|url=http://ezinearticles.com/?Type-I-Vs-Type-II-Muscle-Fibers-and-Weight-Lifting-Programs&id=971098
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|date=n.d.
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|author=Nick H.
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|publisher=EzineArticles.com
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|accessdate=2008-05-13
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}}</ref> A new study in the February issue of ''Cell Metabolism'' suggests that in regards to weight loss, lifting weights may be just as important as running on the treadmill.<ref name=Acharya>{{cite web
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|title=Type 2 muscle important in body metabolism and obesity
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|url=http://www.rxpgnews.com/obesity/Type_2_muscle_important_in_controlling_whole-body_metabolism_87484.shtml
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|date=5 February 2008
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|author=Dr. Sanjukta Acharya (review)
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|publisher=Rxpgnews.com
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|accessdate=2008-05-13
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}}</ref>
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==Type IIA Fibers ==
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Type IIA fibers, or fast oxidative fibers, are used more during sustained power activities such as sprinting 400 meters or doing repeated lifts with a weight below maximum (but not with very light weights).<ref name=Leyland_CJ/> They contain very large amounts of myoglobin. Type II A fibers are red, unlike Type II B fibers, which are white. Type IIA fibers have a very high capacity for generating [[ATP]] by oxidative metabolic processes, and split ATP at a very rapid rate. They have a fast contraction velocity and are resistant to fatigue. <ref name=Mac>{{cite web
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|title=Muscle Types
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|url=http://www.brianmac.co.uk/muscle.htm
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|date=n.d.
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|author=Brian Mac
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|publisher=BrianMac.co.uk
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|accessdate=2008-05-13
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}}</ref>
   
 
==Type IIB Fibers==
  
==Type IIB Fibers==
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ATP at a fast rate and have a fast contraction velocity. Such fibres are found in large numbers in the muscles of the arms. <ref name=Mac/>
  
ATP at a fast rate and have a fast contraction velocity. Such fibres are found in large numbers in the muscles of the arms. <ref name=Mac/>
   
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==fack yaw ==
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==See Also==
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[[Types of Muscle Fiber]]
   
 
==References==
  
==References==
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{{reflist|2}}
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[http://www.musclexus.org/ Muscle Factor X]
  
   
 
==External Links==
  
==External Links==

Revision as of 13:03, 22 April 2014

Type II muscle fiber is also known as fast twitch muscle fiber. Muscle fiber types can be broken down into two main types: slow twitch (Type I) muscle fibers and fast twitch (Type II) muscle fibers.[1] These fast twitch fibers can be further categorized into Type IIa and Type IIb fibers,[1] which are also known as "fast twitch oxidative" and "fast twitch glycolytic," respectively. Type I fibers are characterized by low force/power/speed production and high endurance, Type IIB fibers are characterized by high force/power/speed production and low endurance, while Type IIA fall in between the two.[2]

It is possible that a fiber might be transformed from Type IIB to Type IIAB to Type IIA with exercise training.[3] Furthermore, researchers at Boston University School of Medicine have found that increasing the mass or size of type II muscle fibers will lead to a significant decrease in fat mass or the amount of fat in the body.[4] A new study in the February issue of Cell Metabolism suggests that in regards to weight loss, lifting weights may be just as important as running on the treadmill.[5]


Type IIA Fibers 

Type IIA fibers, or fast oxidative fibers, are used more during sustained power activities such as sprinting 400 meters or doing repeated lifts with a weight below maximum (but not with very light weights).[6] They contain very large amounts of myoglobin. Type II A fibers are red, unlike Type II B fibers, which are white. Type IIA fibers have a very high capacity for generating ATP by oxidative metabolic processes, and split ATP at a very rapid rate. They have a fast contraction velocity and are resistant to fatigue. [7]

Type IIB Fibers

Type IIb fast-twitch fibers, or fast glycolytic fibres (also known as Type IIx), are recruited for very short-duration high-intensity bursts of power such as maximal and near-maximal lifts and short sprints.[6] Type IIB fibres contain a low content of myoglobin, relatively few mitochondria, relatively few blood capillaries and large amounts glycogen. Type II B fibres are white, while Type I (slow twitch) fibers are red. Type IIB fibers are geared to generate ATP by anaerobic metabolic processes, however, they are not able to supply skeletal muscle fibres continuously with sufficient ATP, and fatigue easily

ATP at a fast rate and have a fast contraction velocity. Such fibres are found in large numbers in the muscles of the arms. [7]

See Also

Types of Muscle Fiber

References

  1. ↑ 1.0 1.1 Elizabeth Quinn (October 30, 2007). Fast and Slow Twitch Muscle Fibers. About.com. Retrieved on 2008-05-13.
  2. ↑ Baggett, Kelly (n.d.). Understanding Muscle Fiber Types. Bodybuilding.com. Retrieved on 2008-10-17.
  3. ↑ University of Oregon (n.d.). Muscle Physiology. UOregon.edu. Retrieved on 2008-05-13.
  4. ↑ Nick H. (n.d.). Type I Vs Type II Muscle Fibers and Weight Lifting Programs. EzineArticles.com. Retrieved on 2008-05-13.
  5. ↑ Dr. Sanjukta Acharya (review) (5 February 2008). Type 2 muscle important in body metabolism and obesity. Rxpgnews.com. Retrieved on 2008-05-13.
  6. ↑ 6.0 6.1 Leyland, Tony (July 2008). "Human Power Output and Crossfit Metcon Workouts". CrossFit Journal (71). 
  7. ↑ 7.0 7.1 Brian Mac (n.d.). Muscle Types. BrianMac.co.uk. Retrieved on 2008-05-13.

External Links

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