Who knows about fast/slow twich fibers

HyDr8 · 06-23-2003, 05:27 PM

Can a person have both? Are certain muscle groups more likely to be slow vs fast? How do you know what you have? How do you train them?

I know, a lot of questions but I have never gotten a grip on this topic.

Thanks

**Mudge** · 06-23-2003, 06:02 PM

Yes, everyone has a mixture of both. According to what I've read you can even change your percentages through training.

How do you know? I think you'd have to cut open the specific bodypart in question to take a peek. If they have density differences I dont know of it. If it were the case though an XRay might be enough to get a guess.

I dont see that its critical to know though. Either you run fast, or you have lots of endurance, or are somewhere in the middle.

You train them exactly how you want to train them, if you sprint you will favor fast twitch muscle growth - if you run marathons you will favor slow twitch endurance fibers.

gr81 · 06-23-2003, 07:48 PM

fast twitch fibers are recruited with brief, more intense stress put on the muscle (such as sprinting and other types of plyometrics) as where slow twitch fibers are recruited during less intense higher rep sets. It is crucial to know this when training certain bodyparts such as the hamstrings and calves, which are both primarily made up of fast twitch fibers.

gopro · 06-24-2003, 11:30 AM

Here is an article that I wrote for IM some time ago, but it should help you out:

When the average person takes a look at a bodybuilder all he sees is a series of lumps and bumps of varying shapes and sizes. Upon inspection he may find these odd protrusions to be fascinating, cool, or perhaps grotesquemaybe even a little intimidating. But little does he know how complex and intricate all these "lumps" really are!

Let's take a look inside these lumps, see what they are made of and what we can do to make them bigger and stronger. Ok, first let me stop calling them lumps or bumps and refer to them more properly as skeletal muscles, or just muscles for short.

Muscle is composed of bundles of muscle fibers or myofibers. Each fiber is composed of myofibrils, which, in turn, are composed of myofilaments. The myofilaments are made up of two proteins called myosin and actin. The myosin and actin act within the smallest functional unit of muscle, the sarcomere, to produce a contraction. It is the myosin protein, however, which holds the key to the differences in muscle fiber types. (Complicated lumps these muscles, aren't they!) In general, there are four different fiber types in skeletal muscle. These four include: Type I, also known as slow-twitch or red fibers; Type IIA, IID, and IIB, also known collectively as fast-twitch or white fibers.

Type I are the slowest, smallest, and have the highest level of endurance of all the fibers. Next come the Type IIA, IID, and finally the Type IIB, which are the fastest, largest, and least endurance oriented in the group.

As you contract a muscle, you'll recruit those muscle fibers in a specific order. The smallest (lowest threshold) fibers, the Type I, are recruited first. As the speed or force of contraction is increased, you will sequentially recruit the Type IIA, IID, and IIB muscle fibers. However, to recruit the Type IIB fibers it may take over 90% of a maximal contraction!

All people are born with these muscle fiber types. Most muscles contain almost an even split of slow (Type I) and fast (Type II) fibers. There are a few exceptions, however, as the soleus muscle of the calf is predominantly slow twitch, while the gastrocnemius muscle and the hamstrings are predominantly fast twitch. Also, individuals on opposite ends of the athletic spectrum like sprinters and marathon runners for example, may possess a higher percentage of one fiber type.

So what does this mean to all of us bodybuilders? Well, in order to obtain maximal muscle size we must regularly train all of our muscle fibers. A combination of bodybuilding (higher and lower rep), powerlifting, and even a little Olympic-style lifting may be best. Bodybuilding seems to stress the Type I and IIA fibers, while the IIB fibers may be best stimulated through powerlifting and Olympic lifting. The IID fibers are perhaps stressed equally by all three forms of training. I believe that the key to long term progress in bodybuilding can be summed up by one important word: VARIATION!

Doing the same three sets of 8-12 reps over and over will help you to a point. But after that, make a change! By selectively alternating your training volume (total sets/reps), training intensity (weight lifted), training techniques (forced reps, pre-exhaust, supersets, drop sets, etc.), training tempo (rep speed), rest between sets, bodypart arrangement, etc., you're more likely to avoid injuries and overtraining and therefore maximize your gains. As long as the stimulus presented to your muscles is novel and taxing, they will continue to adapt accordingly.

Just remember that your muscle fibers are not static entities they are dynamic and malleable. Therefore you yourself should not be static-don't do the same thing over and over and expect a different result. Don't get stuck in just one type of training program! Be creative! Be dynamic! Your muscles will reward you with continuous gains in size, strength, and endurance. Now, go get to work on those "lumps!"

Robboe · 06-24-2003, 11:55 AM

Ahh yes, the infamous "type IId" muscle fibre article.

I remember this like it was just yesterday...

HyDr8 · 06-24-2003, 12:39 PM

Thanks for the repiles guys. Gopro, thanks for your post too. That clears up a few things for me.

**Prince** · 06-24-2003, 12:55 PM

Quote:

Originally posted by HyDr8
Can a person have both? Are certain muscle groups more likely to be slow vs fast? How do you know what you have? How do you train them?

I know, a lot of questions but I have never gotten a grip on this topic.

Thanks

I also wrote an article recently that explains this briefly:
Training and Hypertrophy - Gain Size!

gopro · 06-24-2003, 06:57 PM

TCD unfortunately is without any muscle fiber and cannot relate to this question at all.

gopro · 06-24-2003, 06:58 PM

Quote:

Originally posted by HyDr8
Thanks for the repiles guys. Gopro, thanks for your post too. That clears up a few things for me.

You are welcome.

gopro · 06-24-2003, 06:59 PM

Quote:

Originally posted by The_Chicken_Daddy
Ahh yes, the infamous "type IId" muscle fibre article.

I remember this like it was just yesterday...

Dude, please...you don't have the mental capacity to remember as far back as yesterday...

FortifiedIron · 06-25-2003, 02:33 AM

Quote:

Originally posted by gopro
Here is an article that I wrote for IM some time ago, but it should help you out:

When the average person takes a look at a bodybuilder all he sees is a series of lumps and bumps of varying shapes and sizes. Upon inspection he may find these odd protrusions to be fascinating, cool, or perhaps grotesquemaybe even a little intimidating. But little does he know how complex and intricate all these "lumps" really are!

Let's take a look inside these lumps, see what they are made of and what we can do to make them bigger and stronger. Ok, first let me stop calling them lumps or bumps and refer to them more properly as skeletal muscles, or just muscles for short.

Muscle is composed of bundles of muscle fibers or myofibers. Each fiber is composed of myofibrils, which, in turn, are composed of myofilaments. The myofilaments are made up of two proteins called myosin and actin. The myosin and actin act within the smallest functional unit of muscle, the sarcomere, to produce a contraction. It is the myosin protein, however, which holds the key to the differences in muscle fiber types. (Complicated lumps these muscles, aren't they!) In general, there are four different fiber types in skeletal muscle. These four include: Type I, also known as slow-twitch or red fibers; Type IIA, IID, and IIB, also known collectively as fast-twitch or white fibers.

Type I are the slowest, smallest, and have the highest level of endurance of all the fibers. Next come the Type IIA, IID, and finally the Type IIB, which are the fastest, largest, and least endurance oriented in the group.

As you contract a muscle, you'll recruit those muscle fibers in a specific order. The smallest (lowest threshold) fibers, the Type I, are recruited first. As the speed or force of contraction is increased, you will sequentially recruit the Type IIA, IID, and IIB muscle fibers. However, to recruit the Type IIB fibers it may take over 90% of a maximal contraction!

All people are born with these muscle fiber types. Most muscles contain almost an even split of slow (Type I) and fast (Type II) fibers. There are a few exceptions, however, as the soleus muscle of the calf is predominantly slow twitch, while the gastrocnemius muscle and the hamstrings are predominantly fast twitch. Also, individuals on opposite ends of the athletic spectrum like sprinters and marathon runners for example, may possess a higher percentage of one fiber type.

So what does this mean to all of us bodybuilders? Well, in order to obtain maximal muscle size we must regularly train all of our muscle fibers. A combination of bodybuilding (higher and lower rep), powerlifting, and even a little Olympic-style lifting may be best. Bodybuilding seems to stress the Type I and IIA fibers, while the IIB fibers may be best stimulated through powerlifting and Olympic lifting. The IID fibers are perhaps stressed equally by all three forms of training. I believe that the key to long term progress in bodybuilding can be summed up by one important word: VARIATION!

Doing the same three sets of 8-12 reps over and over will help you to a point. But after that, make a change! By selectively alternating your training volume (total sets/reps), training intensity (weight lifted), training techniques (forced reps, pre-exhaust, supersets, drop sets, etc.), training tempo (rep speed), rest between sets, bodypart arrangement, etc., you're more likely to avoid injuries and overtraining and therefore maximize your gains. As long as the stimulus presented to your muscles is novel and taxing, they will continue to adapt accordingly.

Just remember that your muscle fibers are not static entities they are dynamic and malleable. Therefore you yourself should not be static-don't do the same thing over and over and expect a different result. Don't get stuck in just one type of training program! Be creative! Be dynamic! Your muscles will reward you with continuous gains in size, strength, and endurance. Now, go get to work on those "lumps!"

Much respect for that piece. Except Im not familiar with the term IID fiber. If you could please clear it up.

Just a tid bit of info, the IIB has been out dated for human's. The FT classification fiber is now the IIX for humans. IIB is only found in mammal life other then us humans. Was a huge study conducted on this information.

I also find it pretty good that you mention the benefits of Olifting and Pling to a bodybuilder. SOmething alot of bbers are overlooking these days.

Kc

Robboe · 06-25-2003, 05:36 AM

Kyle, look up rat muscles. You'll definately find type IId there.

gopro · 06-25-2003, 07:46 AM

Quote:

Originally posted by The_Chicken_Daddy
Kyle, look up rat muscles. You'll definately find type IId there.

I see that I now stand corrected....TCD does have type II D fibers after all...

Robboe · 06-25-2003, 08:54 AM

Very humerous, Eric.

Still doesn't correct you though.

gopro · 06-25-2003, 08:58 AM

Quote:

Originally posted by The_Chicken_Daddy
Very humerous, Eric.

Still doesn't correct you though.

I don't need correction Chicken...when I wrote the article some time ago the research came from Jose Antonio who believed, or believes there are type II D fibers in humans...and also, back then type II B fibers were also desrcibed in humans (to answer Fortified...or your buddy Kyle).

So, go bother him about it, k? I've got more important things to do.

**Prince** · 06-25-2003, 12:54 PM

you two should have your insult exchanges via PM's, it only degrades threads.

Robboe · 06-25-2003, 02:13 PM

I fail to see where i have insulted him in this thread.

End of the day, the "science" behind his article, the outcome of which doesn't necessarily equate to the description beforehand, is wrong and now outdated. He's been told last year that it is wrong and yet he still posted it here. He should either re-write the article or not post it at all.

Eric referenced one study relating to the type IId fibre - the abstract of which i found online (and will happily find again if you so desire). The abstract stated that the study was done using rats quite clearly.

Either he bluffed that he'd read the study or needs quite a serious course in comprehending literature.

FortifiedIron · 06-25-2003, 04:11 PM

Here is an abstract from my article:

4.) What is a muscle fiber?

Your body contains thousands and thousands of muscle fibers. Several of these fibers are bundled together to make up a fasciclei (plural, fasciculi) which is encased in a sheath called a perimysium. Many groups of these fasciculi form the whole muscle, which is then enclosed in another sheath called the epimysium (or fascia). Each fiber cell has several thousand rod-like structures known as myofibrils. Myofibrils consist of a chain of basic contractile units known as sacromeres. Sacromeres consist of both myosin and actin filaments. There are also small areas of the myosin filaments that are called cross bridges. These cross bridges are temporary connected to certain parts of the action filaments that form the basic components for a muscular contraction.

Myosin plays a special role in determining the contractility of the muscle. The myosin heavy chain (MHC) appears in three different iso-forms. They are referred to as I, IIa, and IIx forms. They are also located in the muscle fiber that contains them I-I, IIa-IIa, and IIx-IIx. Ia fibers are referred to as slow twitch muscle fibers (ST/Red), whereas IIa and IIx are referred to as fast twitch muscle fibers(FT/White). Type IIx is the fasting contractile muscle fiber. IIx has a contractile velocity 10 times that of a Ia fiber, where IIa lies between them. I, IIa and IIX fibers also have various other forms as well. These fibers are known as hybird fibers. They are scarce in young people but rather common in adults.

The differences in fiber proportions in the muscles varies dramatically according to the person's genetics and training history. It has been revealed that the elite track athletes and Olympic styles weightlifters (over 60% FT fibers) have three times the fast twitch muscle fibers than that of marathon runners (17% FT) and 50% greater than in bodybuilders (40% FT fibers). Sub-maximal and high explosive weight training also produces greater hypertrophy of FT fibers. The potential for the body to generate high power output in Olympic style weightlifting movements and other forms of speed movements is greatly determined by the proportion of FT fibers.

In every movement different muscle fiber types are recruited and fired. The velocity, load, and duration of the movement determines which fiber type is most dominantly recruited and fired. The first fiber is the Ia which is resistance to fatigue and lasts a prolonged period of time. The second fiber recruited is the IIa which is a fast twitch fiber which lasts an intermediate amount of time. The last fiber to be recruited is the IIX fiber which also has the strongest contractile output. Olympic lifters have a higher firing rate of FT fibers then ST fibers, whereas bodybuilders have a higher firing rate of ST fibers then FT fibers. The reason for the differences is Olympic lifters train with lower repetition sets, where their resistance is heavier and more explosive then that of a bodybuilder who normally trains with moderately heavy weight slowly to failure.

(Andersen et al, 2000;Hakkinen, 1985)
----------------------------------------------------------------------------

I personally do not have a clue what IID is, I've spent alot of time studying in this area, its the first i've heard of it. Im not saying either is wrong or write. Its just strickingly odd to me. The only studies I have ever read that had to do with rats/lab animals was when i was studying hyperplasia. Yet I still didnt not find the term IID used. I'll look it up in my books later this afternoon.

Kc

FortifiedIron · 06-25-2003, 04:16 PM

IID has to be a term used for hyperplasia fibers. Its a 100% proven 'theory'

What is hyperplasia?

Very little is known about hyperplasia. Hyperplasia is the splitting of muscle fibers. There has been testing done with animals such as cats (and rats) that have shown muscle fiber splitting. These cats where subjected to heavy resistance training for a prolonged period of time. It has also been noted that many Russian scientists have conclusively come to the finding that muscular mass is not only through hypertrophy of muscle fibers (enlarging) but also as an increase in fiber number by means of splitting into smaller sections. It has also been documented that satellite cells, which can activate new cell formation, have been shown to be associated with muscle hyperplasia, through stretching and dynamic exercises. Many people believe that hyperplasia does exist in humans possibly through heavy intensive training sessions, but lack of human testing cannot conclude this.

(Gudz, 1968,1976;Gonyea, 1980; Hether et al, 1991; Tamaki et al, 1992; Antonio & Gonyea, 1994)

other cites to Antonio's study on hyperplasia:

Antonio J & Gonyea W (1993) Skeletal muscles fiber hyperplasia Med SCI Sports Exerc Dec; 25(12): 1333-45

Still digging for more info so plz be patient.

Kc

Robboe · 06-25-2003, 04:29 PM

Here's a link to the study Gopro originally cited as his reference: http://www.ncbi.nlm.nih.gov/entrez/q...&dopt=Abstract

gopro · 06-25-2003, 05:02 PM

I didn't reference any article. I wrote the article from notes that I had gathered from several sources, one of which was an article by Jose Antonio PHD.

Trust me, I do not need a lesson from either TCD of FI on fiber types, hyperplasia, or any other subject relating to this field. I am extremely well schooled in the subject and could write a book on it if I felt like it.

I posted the article just to give the original poster some basic info.

Twin Peak · 06-25-2003, 05:08 PM

GoPro, I don't know shit about fiber types, but if there is no evidence that IId fiber types exist in humans, and indeed there is evidence to the contrary (I am not going to bother to look) than that is shameful.

FortifiedIron · 06-25-2003, 05:19 PM

Quote:

Originally posted by gopro
I didn't reference any article. I wrote the article from notes that I had gathered from several sources, one of which was an article by Jose Antonio PHD.

Trust me, I do not need a lesson from either TCD of FI on fiber types, hyperplasia, or any other subject relating to this field. I am extremely well schooled in the subject and could write a book on it if I felt like it.

I posted the article just to give the original poster some basic info.

Im not here to disprove or prove you wrong. I just have never heard of the IID fiber ever used. Now that I know what it is, I have furthur educated myself on the subject.

Why you didnt cite the information from the article I have no clue.

If you can write a book on the subject plz be my guest, id love to read it and give it my review. If you ever feel like you can and do plz contact me.

Kc

Robboe · 06-25-2003, 05:42 PM

Quote:

Originally posted by gopro
I didn't reference any article. I wrote the article from notes that I had gathered from several sources, one of which was an article by Jose Antonio PHD.

The link i posted was the title you gave on WBB when you were first queried about your inclusion of type IId fibres in your article.

I will re-state: I think you may need "schooling" on how to comprehend what you read, if in fact you did read it at all.

If you could write a book then i implore you to. Of course i imagine it'll just be a cut & paste job, which the article you posted above very much resembles, save for the last three paragraphs.

Snake_Eyes · 06-25-2003, 05:54 PM

Quote:

Originally posted by FortifiedIron
Your body contains thousands and thousands of muscle fibers. Several of these fibers are bundled together to make up a fasciclei (plural, fasciculi) which is encased in a sheath called a perimysium. Many groups of these fasciculi form the whole muscle, which is then enclosed in another sheath called the epimysium (or fascia). Each fiber cell has several thousand rod-like structures known as myofibrils. Myofibrils consist of a chain of basic contractile units known as sacromeres. Sacromeres consist of both myosin and actin filaments. There are also small areas of the myosin filaments that are called cross bridges. These cross bridges are temporary connected to certain parts of the action filaments that form the basic components for a muscular contraction.

Myosin plays a special role in determining the contractility of the muscle. The myosin heavy chain (MHC) appears in three different iso-forms. They are referred to as I, IIa, and IIx forms. They are also located in the muscle fiber that contains them I-I, IIa-IIa, and IIx-IIx. Ia fibers are referred to as slow twitch muscle fibers (ST/Red), whereas IIa and IIx are referred to as fast twitch muscle fibers(FT/White). Type IIx is the fasting contractile muscle fiber. IIx has a contractile velocity 10 times that of a Ia fiber, where IIa lies between them. I, IIa and IIX fibers also have various other forms as well. These fibers are known as hybird fibers. They are scarce in young people but rather common in adults.

The differences in fiber proportions in the muscles varies dramatically according to the person's genetics and training history. It has been revealed that the elite track athletes and Olympic styles weightlifters (over 60% FT fibers) have three times the fast twitch muscle fibers than that of marathon runners (17% FT) and 50% greater than in bodybuilders (40% FT fibers). Sub-maximal and high explosive weight training also produces greater hypertrophy of FT fibers. The potential for the body to generate high power output in Olympic style weightlifting movements and other forms of speed movements is greatly determined by the proportion of FT fibers.

In every movement different muscle fiber types are recruited and fired. The velocity, load, and duration of the movement determines which fiber type is most dominantly recruited and fired. The first fiber is the Ia which is resistance to fatigue and lasts a prolonged period of time. The second fiber recruited is the IIa which is a fast twitch fiber which lasts an intermediate amount of time. The last fiber to be recruited is the IIX fiber which also has the strongest contractile output. Olympic lifters have a higher firing rate of FT fibers then ST fibers, whereas bodybuilders have a higher firing rate of ST fibers then FT fibers. The reason for the differences is Olympic lifters train with lower repetition sets, where their resistance is heavier and more explosive then that of a bodybuilder who normally trains with moderately heavy weight slowly to failure.

(Andersen et al, 2000;Hakkinen, 1985)
----------------------------------------------------------------------------

I personally do not have a clue what IID is, I've spent alot of time studying in this area, its the first i've heard of it. Im not saying either is wrong or write. Its just strickingly odd to me. The only studies I have ever read that had to do with rats/lab animals was when i was studying hyperplasia. Yet I still didnt not find the term IID used. I'll look it up in my books later this afternoon.

Kc

This is pretty much dead-on.

The only thing I have to add is that metabolic character, while related to MHC expression (and thereby shortening velocity, which is a function of the MHC isoform, and MU innervation), is wholly independent of any of the above qualities.

That is, whether a fiber is oxidative, glycolytic, or hybrid is related to the fiber's function, not its capability.

This is why training in regards to muscle fibers is practically useless. One should train either for neural function or metabolic character. Trying to organize training around "targeting" specific fibers is next to useless.

For example, one cannot train the vast majority of ST fibers without extreme endurance exercise, as most of them have fatigue times over several minutes up to several hours. No standard weight training will effect these to any meaningful degree.

Robboe · 06-25-2003, 05:59 PM

Crikey.

I think this is the time where i casually slinker off, cause this is over my head now.

FortifiedIron · 06-25-2003, 06:20 PM

Quote:

[i][b]
For example, one cannot train the vast majority of ST fibers without extreme endurance exercise, as most of them have fatigue times over several minutes up to several hours. No standard weight training will effect these to any meaningful degree.

Are you trying to suggest that by slow, controlled movements done to exceed up to 10+ reps will not greatly effect the recruitment and fire of ST fibers?

Kc

Snake_Eyes · 06-25-2003, 06:33 PM

Pretty much, yup.

The true oxidative type I fibers have exceedingly high fatigue thresholds.....I can't see a set short of 50-100 reps doing anything for the vast majority of them.

gopro · 06-25-2003, 06:49 PM

Quote:

Originally posted by The_Chicken_Daddy
The link i posted was the title you gave on WBB when you were first queried about your inclusion of type IId fibres in your article.

I will re-state: I think you may need "schooling" on how to comprehend what you read, if in fact you did read it at all.

If you could write a book then i implore you to. Of course i imagine it'll just be a cut & paste job, which the article you posted above very much resembles, save for the last three paragraphs.

A. I gave no references with my article...someone else may have found the link

B. I could and eventually will write a book, but it will involve all aspects of fitness/nutrition/drugs/supplements/contest prep/personal training/gym ownership/and more. You can go read the 3 articles that I wrote for MMI to see whether they were cut and paste, or go ask the CEO of VPX why he headhunted me out of thousands upon thousands of people in the industry to head up his websites, write for the magazine, write ad copy, and represent the company at seminars and other functions.

C. I crack up at the thought that "I" need more schooling to learn to comprehend what I read, as I'm sure that I have more knowledge in my small toe than you have in your entire head.

I also find it sooo hilarious that you need to bring "backup" with you everytime you want to get another wasteful point across.

Please Chicken, I IMPLORE YOU...dude, get a life.

Robboe · 06-26-2003, 05:08 AM

Quote:

Originally posted by gopro
A. I gave no references with my article...someone else may have found the link

Again, your comprehension skills are marvellous. I didn't say you gave a reference with your article. In fact, your article had no references. I said "The link i posted was the title you gave on WBB when you were first queried about your inclusion of type IId fibres in your article."

In laymans - when you were called out, this is the study you highlighted as your source.

Quote:

B. I could and eventually will write a book, but it will involve all aspects of fitness/nutrition/drugs/supplements/contest prep/personal training/gym ownership/and more. You can go read the 3 articles that I wrote for MMI to see whether they were cut and paste, or go ask the CEO of VPX why he headhunted me out of thousands upon thousands of people in the industry to head up his websites, write for the magazine, write ad copy, and represent the company at seminars and other functions.

You mention the magazine and supplement company like i care?

I fail to see your point by illustrating that you write for a magazine i don't like (and know many others who don't) and work for a company i certainly don't care for. In fact, i can think of only two people on all the boards i frequent who actually like VPX - you and BigSwole.

Quote:

C. I crack up at the thought that "I" need more schooling to learn to comprehend what I read, as I'm sure that I have more knowledge in my small toe than you have in your entire head.

Well you said it, so it must be true.

Quote:

I also find it sooo hilarious that you need to bring "backup" with you everytime you want to get another wasteful point across.

I invited no one over here. I just know Fortified Iron's name and that he runs a message board. He sent me a PM after i posted asking who i am.

However, all this matters little because it doesn't alter the fact that the "science" behind your article is completely flawed and inaccurate.

06-23-2003, 05:27 PM	#1
HyDr8 Registered User Join Date: May 2003 Posts: 118	Who knows about fast/slow twich fibers Can a person have both? Are certain muscle groups more likely to be slow vs fast? How do you know what you have? How do you train them? I know, a lot of questions but I have never gotten a grip on this topic. Thanks I love the sound of clanging iron in the morning. It sounds like victory.

06-23-2003, 06:02 PM	#2
Mudge Dieting I swear! Super Moderator Join Date: Jun 2002 Location: Here Posts: 23,474 Photos: 1	Yes, everyone has a mixture of both. According to what I've read you can even change your percentages through training. How do you know? I think you'd have to cut open the specific bodypart in question to take a peek. If they have density differences I dont know of it. If it were the case though an XRay might be enough to get a guess. I dont see that its critical to know though. Either you run fast, or you have lots of endurance, or are somewhere in the middle. You train them exactly how you want to train them, if you sprint you will favor fast twitch muscle growth - if you run marathons you will favor slow twitch endurance fibers. Kinesiology Comp Bench MaxCalc Motivation Bench form Charles Poliquin When I let go of what I am, I become what I might be. Lao-Tzu

06-24-2003, 11:30 AM	#4
gopro NGA/IFPA Pro Bodybuilder Elite Member Join Date: Jul 2001 Location: GLOBAL! Posts: 10,893	Here is an article that I wrote for IM some time ago, but it should help you out: When the average person takes a look at a bodybuilder all he sees is a series of lumps and bumps of varying shapes and sizes. Upon inspection he may find these odd protrusions to be fascinating, cool, or perhaps grotesquemaybe even a little intimidating. But little does he know how complex and intricate all these "lumps" really are! Let's take a look inside these lumps, see what they are made of and what we can do to make them bigger and stronger. Ok, first let me stop calling them lumps or bumps and refer to them more properly as skeletal muscles, or just muscles for short. Muscle is composed of bundles of muscle fibers or myofibers. Each fiber is composed of myofibrils, which, in turn, are composed of myofilaments. The myofilaments are made up of two proteins called myosin and actin. The myosin and actin act within the smallest functional unit of muscle, the sarcomere, to produce a contraction. It is the myosin protein, however, which holds the key to the differences in muscle fiber types. (Complicated lumps these muscles, aren't they!) In general, there are four different fiber types in skeletal muscle. These four include: Type I, also known as slow-twitch or red fibers; Type IIA, IID, and IIB, also known collectively as fast-twitch or white fibers. Type I are the slowest, smallest, and have the highest level of endurance of all the fibers. Next come the Type IIA, IID, and finally the Type IIB, which are the fastest, largest, and least endurance oriented in the group. As you contract a muscle, you'll recruit those muscle fibers in a specific order. The smallest (lowest threshold) fibers, the Type I, are recruited first. As the speed or force of contraction is increased, you will sequentially recruit the Type IIA, IID, and IIB muscle fibers. However, to recruit the Type IIB fibers it may take over 90% of a maximal contraction! All people are born with these muscle fiber types. Most muscles contain almost an even split of slow (Type I) and fast (Type II) fibers. There are a few exceptions, however, as the soleus muscle of the calf is predominantly slow twitch, while the gastrocnemius muscle and the hamstrings are predominantly fast twitch. Also, individuals on opposite ends of the athletic spectrum like sprinters and marathon runners for example, may possess a higher percentage of one fiber type. So what does this mean to all of us bodybuilders? Well, in order to obtain maximal muscle size we must regularly train all of our muscle fibers. A combination of bodybuilding (higher and lower rep), powerlifting, and even a little Olympic-style lifting may be best. Bodybuilding seems to stress the Type I and IIA fibers, while the IIB fibers may be best stimulated through powerlifting and Olympic lifting. The IID fibers are perhaps stressed equally by all three forms of training. I believe that the key to long term progress in bodybuilding can be summed up by one important word: VARIATION! Doing the same three sets of 8-12 reps over and over will help you to a point. But after that, make a change! By selectively alternating your training volume (total sets/reps), training intensity (weight lifted), training techniques (forced reps, pre-exhaust, supersets, drop sets, etc.), training tempo (rep speed), rest between sets, bodypart arrangement, etc., you're more likely to avoid injuries and overtraining and therefore maximize your gains. As long as the stimulus presented to your muscles is novel and taxing, they will continue to adapt accordingly. Just remember that your muscle fibers are not static entities they are dynamic and malleable. Therefore you yourself should not be static-don't do the same thing over and over and expect a different result. Don't get stuck in just one type of training program! Be creative! Be dynamic! Your muscles will reward you with continuous gains in size, strength, and endurance. Now, go get to work on those "lumps!" All American EFX Sponsored Pro Bodybuilder/Internet Marketing Manager P/RR/S DVD and E-Book now available! P/RR/S DVD http://www.home-gym.com/erbrporepras.html P/RR/S E-BOOK html www.X-traordinaryWorkouts.com Monthly columnist for Muscular Development and Ironman magazines. www.prrstraining.com Time to GROW Without Plateau! Personal Training Gopro is available for online personal training, dietary guidance, and contest prep coaching. Send me a PM or e-mail if interested. Thank you.

06-24-2003, 11:55 AM	#5
Robboe Designer Supplements Join Date: Dec 2000 Location: Newcastle Posts: 5,141	Ahh yes, the infamous "type IId" muscle fibre article. I remember this like it was just yesterday... Being held down by The Man

06-24-2003, 12:39 PM	#6
HyDr8 Registered User Join Date: May 2003 Posts: 118	Thanks for the repiles guys. Gopro, thanks for your post too. That clears up a few things for me. I love the sound of clanging iron in the morning. It sounds like victory.

06-23-2003, 07:48 PM	#3
gr81 You Lack Intensity!!!! Elite Member Join Date: Mar 2003 Location: Just below our civil disguise Posts: 6,378 Photos: 10	fast twitch fibers are recruited with brief, more intense stress put on the muscle (such as sprinting and other types of plyometrics) as where slow twitch fibers are recruited during less intense higher rep sets. It is crucial to know this when training certain bodyparts such as the hamstrings and calves, which are both primarily made up of fast twitch fibers.

06-24-2003, 06:57 PM	#8
gopro NGA/IFPA Pro Bodybuilder Elite Member Join Date: Jul 2001 Location: GLOBAL! Posts: 10,893	TCD unfortunately is without any muscle fiber and cannot relate to this question at all. All American EFX Sponsored Pro Bodybuilder/Internet Marketing Manager P/RR/S DVD and E-Book now available! P/RR/S DVD http://www.home-gym.com/erbrporepras.html P/RR/S E-BOOK html www.X-traordinaryWorkouts.com Monthly columnist for Muscular Development and Ironman magazines. www.prrstraining.com Time to GROW Without Plateau! Personal Training Gopro is available for online personal training, dietary guidance, and contest prep coaching. Send me a PM or e-mail if interested. Thank you.

06-25-2003, 05:36 AM	#12
Robboe Designer Supplements Join Date: Dec 2000 Location: Newcastle Posts: 5,141	Kyle, look up rat muscles. You'll definately find type IId there. Being held down by The Man

06-25-2003, 08:54 AM	#14
Robboe Designer Supplements Join Date: Dec 2000 Location: Newcastle Posts: 5,141	Very humerous, Eric. Still doesn't correct you though. Being held down by The Man

06-25-2003, 12:54 PM	#16
Prince IronMagLabs Owner Administrator Join Date: Nov 2000 Location: Colorado Posts: 37,397 Photos: 356	you two should have your insult exchanges via PM's, it only degrades threads. BOARD SPONSORS: MassNutrition.com - Discount Supplement Superstore IronMagLabs.com - Bodybuilding Nutrition AlltheWhey.com - Bulk Protein Powders & Supplements CEMProducts.com - Research Chemicals & Supplements MusclesProd.com - Steroids, Bodybuilding & Training Blog Maximizer.com - Maximum Strength for Maximum Performance MikeGetsRipped.com - The Original 'Get Ripped' Blog ProteinRoutine.com - Experiments in Healthy Living Follow on Twitter Join Facebook Group Befriend on Myspace

06-25-2003, 02:13 PM	#17
Robboe Designer Supplements Join Date: Dec 2000 Location: Newcastle Posts: 5,141	I fail to see where i have insulted him in this thread. End of the day, the "science" behind his article, the outcome of which doesn't necessarily equate to the description beforehand, is wrong and now outdated. He's been told last year that it is wrong and yet he still posted it here. He should either re-write the article or not post it at all. Eric referenced one study relating to the type IId fibre - the abstract of which i found online (and will happily find again if you so desire). The abstract stated that the study was done using rats quite clearly. Either he bluffed that he'd read the study or needs quite a serious course in comprehending literature. Being held down by The Man

06-25-2003, 04:11 PM	#18
FortifiedIron Registered User Join Date: Mar 2003 Location: Earth Posts: 144	Here is an abstract from my article: 4.) What is a muscle fiber? Your body contains thousands and thousands of muscle fibers. Several of these fibers are bundled together to make up a fasciclei (plural, fasciculi) which is encased in a sheath called a perimysium. Many groups of these fasciculi form the whole muscle, which is then enclosed in another sheath called the epimysium (or fascia). Each fiber cell has several thousand rod-like structures known as myofibrils. Myofibrils consist of a chain of basic contractile units known as sacromeres. Sacromeres consist of both myosin and actin filaments. There are also small areas of the myosin filaments that are called cross bridges. These cross bridges are temporary connected to certain parts of the action filaments that form the basic components for a muscular contraction. Myosin plays a special role in determining the contractility of the muscle. The myosin heavy chain (MHC) appears in three different iso-forms. They are referred to as I, IIa, and IIx forms. They are also located in the muscle fiber that contains them I-I, IIa-IIa, and IIx-IIx. Ia fibers are referred to as slow twitch muscle fibers (ST/Red), whereas IIa and IIx are referred to as fast twitch muscle fibers(FT/White). Type IIx is the fasting contractile muscle fiber. IIx has a contractile velocity 10 times that of a Ia fiber, where IIa lies between them. I, IIa and IIX fibers also have various other forms as well. These fibers are known as hybird fibers. They are scarce in young people but rather common in adults. The differences in fiber proportions in the muscles varies dramatically according to the person's genetics and training history. It has been revealed that the elite track athletes and Olympic styles weightlifters (over 60% FT fibers) have three times the fast twitch muscle fibers than that of marathon runners (17% FT) and 50% greater than in bodybuilders (40% FT fibers). Sub-maximal and high explosive weight training also produces greater hypertrophy of FT fibers. The potential for the body to generate high power output in Olympic style weightlifting movements and other forms of speed movements is greatly determined by the proportion of FT fibers. In every movement different muscle fiber types are recruited and fired. The velocity, load, and duration of the movement determines which fiber type is most dominantly recruited and fired. The first fiber is the Ia which is resistance to fatigue and lasts a prolonged period of time. The second fiber recruited is the IIa which is a fast twitch fiber which lasts an intermediate amount of time. The last fiber to be recruited is the IIX fiber which also has the strongest contractile output. Olympic lifters have a higher firing rate of FT fibers then ST fibers, whereas bodybuilders have a higher firing rate of ST fibers then FT fibers. The reason for the differences is Olympic lifters train with lower repetition sets, where their resistance is heavier and more explosive then that of a bodybuilder who normally trains with moderately heavy weight slowly to failure. (Andersen et al, 2000;Hakkinen, 1985) ---------------------------------------------------------------------------- I personally do not have a clue what IID is, I've spent alot of time studying in this area, its the first i've heard of it. Im not saying either is wrong or write. Its just strickingly odd to me. The only studies I have ever read that had to do with rats/lab animals was when i was studying hyperplasia. Yet I still didnt not find the term IID used. I'll look it up in my books later this afternoon. Kc Http://www.FortifiedIron.com RKM Training Solutions, LLC l Per Ferrum, as Astra-Mel Siff

06-25-2003, 04:16 PM	#19
FortifiedIron Registered User Join Date: Mar 2003 Location: Earth Posts: 144	IID has to be a term used for hyperplasia fibers. Its a 100% proven 'theory' What is hyperplasia? Very little is known about hyperplasia. Hyperplasia is the splitting of muscle fibers. There has been testing done with animals such as cats (and rats) that have shown muscle fiber splitting. These cats where subjected to heavy resistance training for a prolonged period of time. It has also been noted that many Russian scientists have conclusively come to the finding that muscular mass is not only through hypertrophy of muscle fibers (enlarging) but also as an increase in fiber number by means of splitting into smaller sections. It has also been documented that satellite cells, which can activate new cell formation, have been shown to be associated with muscle hyperplasia, through stretching and dynamic exercises. Many people believe that hyperplasia does exist in humans possibly through heavy intensive training sessions, but lack of human testing cannot conclude this. (Gudz, 1968,1976;Gonyea, 1980; Hether et al, 1991; Tamaki et al, 1992; Antonio & Gonyea, 1994) other cites to Antonio's study on hyperplasia: Antonio J & Gonyea W (1993) Skeletal muscles fiber hyperplasia Med SCI Sports Exerc Dec; 25(12): 1333-45 Still digging for more info so plz be patient. Kc Http://www.FortifiedIron.com RKM Training Solutions, LLC l Per Ferrum, as Astra-Mel Siff

06-25-2003, 04:29 PM	#20
Robboe Designer Supplements Join Date: Dec 2000 Location: Newcastle Posts: 5,141	Here's a link to the study Gopro originally cited as his reference: http://www.ncbi.nlm.nih.gov/entrez/q...&dopt=Abstract Being held down by The Man

06-25-2003, 05:02 PM	#21
gopro NGA/IFPA Pro Bodybuilder Elite Member Join Date: Jul 2001 Location: GLOBAL! Posts: 10,893	I didn't reference any article. I wrote the article from notes that I had gathered from several sources, one of which was an article by Jose Antonio PHD. Trust me, I do not need a lesson from either TCD of FI on fiber types, hyperplasia, or any other subject relating to this field. I am extremely well schooled in the subject and could write a book on it if I felt like it. I posted the article just to give the original poster some basic info. All American EFX Sponsored Pro Bodybuilder/Internet Marketing Manager P/RR/S DVD and E-Book now available! P/RR/S DVD http://www.home-gym.com/erbrporepras.html P/RR/S E-BOOK html www.X-traordinaryWorkouts.com Monthly columnist for Muscular Development and Ironman magazines. www.prrstraining.com Time to GROW Without Plateau! Personal Training Gopro is available for online personal training, dietary guidance, and contest prep coaching. Send me a PM or e-mail if interested. Thank you.

06-25-2003, 05:08 PM	#22
Twin Peak Peak Physiques™ Join Date: Mar 2002 Location: NY Posts: 7,870	GoPro, I don't know shit about fiber types, but if there is no evidence that IId fiber types exist in humans, and indeed there is evidence to the contrary (I am not going to bother to look) than that is shameful. www.DesignerSupps.com INTELLIGENT DESIGN™...lands on 1/1/2007 www.intelligentdesignmag.com

06-25-2003, 05:59 PM	#26
Robboe Designer Supplements Join Date: Dec 2000 Location: Newcastle Posts: 5,141	Crikey. I think this is the time where i casually slinker off, cause this is over my head now. Being held down by The Man

06-25-2003, 06:33 PM	#28
Snake_Eyes Real American Hero Join Date: May 2002 Location: Nevada Posts: 221	Pretty much, yup. The true oxidative type I fibers have exceedingly high fatigue thresholds.....I can't see a set short of 50-100 reps doing anything for the vast majority of them.

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