Dr. Squat - Dr. Fred Hatfield

effrey Vaughn
User Question for Todd Wilson....
Saturday, October 8, 2005 11:24 PM NEW!

I just read your article on "functional hypertrophy". It was interesting and informative but I have a question.
I discuss the "size vs strength" issue with some high level bodybuilders I know here locally. These are guys that make me look like a twig if they stand next to me. One of the claims they make is that most of the size comes not only from the water retention relating to the drug use but also due to capillary size within the muscle structure. They claim that the constant flood of blood they get from training more for a pump has a long term effect of increasing their capillary size.

What are your thoughts on this claim and does an increased capillary size imply a reduced quality of functional muscle when comparing muscles of the same size. Does a lifter with increased capillary size tend to have more size then strength, or is this not a factor that is significant in the argument?

Thanks.

Jeffrey Vaughn

http://www.geocities.com/vaughnpower/1.html

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Carlo Buzzichelli
User Question for Todd Wilson....
Sunday, October 9, 2005 10:08 AM NEW!

Jeffrey,
A bodybuilder experience hypertrophy both at sarcomeric and sarcoplasmic level. He might experience capillary hypertrophy and/or increase of their number, but it doesn't make a significant contribution to overall muscular size, in fact marathoners are the athletes that train capillarization the most.. enough said.

You might find the following study interesting:

Muscle fiber hypertrophy, hyperplasia, and capillary density in college men after resistance training.

McCall GE, Byrnes WC, thingyinson A, Pattany PM, Fleck SJ.

Best, C.B.

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Todd Wilson
User Question for Todd Wilson....
Sunday, October 9, 2005 12:52 PM NEW!

I agree with Carlo. Bodybuilders often hold to myths and misunderstandings that are simply part of the culture. Water retention only makes a difference on look or hypertrophy at the national level competitions. Also, water retention as a result of drugs, creatine, or anything else is vastly overstated. If anything carb intake effects water retention more than anything else. But even then it's not going to play a huge role in how they look or perceived muscle size until they are in competition shape and are dropping below 4% bodyfat. They will have greater capillary density, but like Carlo said, it's not going to have any effect on how big they look. Bodybuilders because of their wide re range will have greater sarcoplasmic hypertrophy than someone like yourself and while your type IIA and IIB fibers would appear much bigger if you did a muscle biopsy they would have large Type I fibers as well, while your type I fibers would be rather puny because you never use them.
Also, they would probably have a greater percentage of type IIA fibers hypertrophied compared to you who is basically a walking talking type IIB fiber.

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Jeffrey Vaughn
User Question for Todd Wilson....
Sunday, October 9, 2005 1:19 PM NEW!

I understand...thanks guys.
Jeffrey Vaughn

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Jeffrey Vaughn
User Question for Todd Wilson....
Sunday, October 9, 2005 1:33 PM NEW!

Todd,
"Also, water retention as a result of drugs, creatine, or anything else is vastly overstated."

The ultra fast weight gain is due to what, if water retention is not the culprit?

To qualify; ultra fast may be 30 pounds in 30 days...

Jeffrey Vaughn

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Todd Wilson
User Question for Todd Wilson....
Sunday, October 9, 2005 2:14 PM NEW!

Well, are you referring to creatine or drugs? Regardless, 30 pounds in 30 days is hard to do. In creatine, there is some nominal water retention, but over the last few years it's been grossly overstated by various authors. There is a plethora of evidence supporting the fact that creatine supports gains in lean tissue and those gains are kept after one discontinues creatine use.
As for drugs, realize that gaining 30 pounds while not incresing body fat still isn't thirty pounds of muscle. New Muscle requires more sarcoplasm, capillaries, additional skin (as the body grows), etc., etc. So while we can use weight as an onjective measure of muscle gain or loss, it isn't completely accurate.

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Jeffrey Vaughn
User Question for Todd Wilson....
Sunday, October 9, 2005 2:49 PM NEW!

Yes, we are talking about anabolic drugs not creatine.
...so if we know it is not lean tissue gains and we think it is not water retention, then what is it. I know from watching then lift that it is not quality functional muscle. I was just told from you and Carlo that it is not capillary size....what is left.

Let's stick with the 30 pounds in 30 days with no increase in BF...I thought we assumed the BF would not change. The BB I know would freak out if they put on any fat at all. They will take $2,500 of juice in a month but they will not go near a ham burger...

We have ruled out muscle gains, water and capillary size...give me something to go on here.

Jeffrey Vaughn

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Todd Wilson
User Question for Todd Wilson....
Sunday, October 9, 2005 3:00 PM NEW!

Yes, we are talking about anabolic drugs not creatine.
...so if we know it is not lean tissue gains and we think it is not water retention, then what is it. I know from watching then lift that it is not quality functional muscle. I was just told from you and Carlo that it is not capillary size....what is left.

### Well, understand, lean muscle tissue does acount for a lot of it, however.....because of they use a higher number of reps, while the cross section of the muscle will get bigger, they will expierience a greater degree of sarcoplasmic hypertrophy, as opposed to sarcomeric hypertrophy. The reason the muscle is not as "functional" per se is because the sarcomere, not the sarcoplasm is what does the contracting. Furthermore, a BBer your size can't lift the same weight because his type I and type IIA fibers are more hypertrophied compared to you who's type IIB fibers are more hypertrophied. Type I and IIA do not have the ability to produce as much force as the type IIB fibers do.

Let's stick with the 30 pounds in 30 days with no increase in BF...I thought we assumed the BF would not change. The BB I know would freak out if they put on any fat at all. They will take $2,500 of juice in a month but they will not go near a ham burger...

We have ruled out muscle gains, water and capillary size...give me something to go on here.

### Well, it's not NOT muscle gains, they are gaining some muscle, but again one muscle size and muscle strength are not a one to one proposition except in beginners.

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Mourad Tariq
User Question for Todd Wilson....
Sunday, October 9, 2005 4:47 PM NEW!

"Also, they would probably have a greater percentage of type IIA fibers hypertrophied compared to you who is basically a walking talking type IIB fiber"
- Todd, I agree with most of what you said, but Vaughn as a walking type IIB fiber? As a powerlifter Vaughn is mostly Type IIA fibers, unless he is doing plyometrics or ballistic training (he might be) most of his hypertrophy is IIA. This is one of the reasons that powerlifters still usually have some size, wheras olympic lifters can really be amazing, when you look at the little amount of hypertrophy they have compared to the amount of power they produce.

- Jeffrey:

**for the most part a bodybuilders training is functional, it's just functional in a different way than yours. Sarcoplasmic hypertrophy has its benefits. While you may squat 950 pounds bodybuilders your size may be able to out rep you with 400 pounds. That's the functional effect of their training.

** about the water thing from the drugs... It is and it isn't. If you are comparing yourself to a bodybuilder who is taking a lot of aromatizing drugs and gaining mass, then their muscles will be very full looking due to water. However it usually wont be much more than 10-15 pounds. However, a bodybuilder in contest shape actually holds way less water than you do, so if you are comparing muscle size with him, yours actually look a little bigger due to water.

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Todd Wilson
User Question for Todd Wilson....
Sunday, October 9, 2005 5:02 PM NEW!

Todd, I agree with most of what you said, but Vaughn as a walking type IIB fiber?
### Well first, understand this is more of a facecious joke than a dclarative factual statement.

As a powerlifter Vaughn is mostly Type IIA fibers, unless he is doing plyometrics or ballistic training (he might be) most of his hypertrophy is IIA.

### No, because look at the percentages with relation to 1RM Jeffrey lifts with. Consistent use of maximal weights (defined as 85% and above 1 RM) will improve one's ability to recruit the higher threshold motor units. There's no doubting that pleny of type IIAs have been recruited and hypretrophied as well, but training with maximal weights allows one to recruit the type IIAs, henc ethe benefit of lifting heavy.

This is one of the reasons that powerlifters still usually have some size,

### Type IIB fibers have the most potential for growth.

wheras olympic lifters can really be amazing, when you look at the little amount of hypertrophy they have compared to the amount of power they produce.

### I would disagree, hypertrophy in weightlifters usually occurs in their legs and upper backs. They tend to carry more hypertrophy there simply because of the greater amount of volume of their lifts work those muscles. Powerlifters will often have comparable upper backs and much larger chests, but rarely is their leg development comparable to a weightlifter of the same weight class. Also, despite the weight class more powerlifters use methods that improve maximal strength (i.e., strength without regards to bodyweight), weightlifters use methods that more closely follow the lines of relative strength, particularly after several years of training.

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Mourad Tariq
User Question for Todd Wilson....
Sunday, October 9, 2005 6:20 PM NEW!

### No, because look at the percentages with relation to 1RM Jeffrey lifts with. Consistent use of maximal weights (defined as 85% and above 1 RM) will improve one's ability to recruit the higher threshold motor units. There's no doubting that pleny of type IIAs have been recruited and hypretrophied as well, but training with maximal weights allows one to recruit the type IIAs, henc ethe benefit of lifting heavy.
** Yes he uses heavy weight, however he is still a powerlifter, meaning he training for high force & low velocity movements. I know that their may be some plyometric effect to some of the band work Vaughn does, but the fact is he is training to lift a really big weight up without regard to speed. Studies show that powerlifters have less type IIB fibers (1.3%) than untrained men (12%. This is because unless they are doing ballistic training (altitude landings, etc) they are still converting most of their type IIB to type IIA. I am willing to admit Vaughns band workouts may make him a little more plyometric than many lifters, but he is still a powerlifter.

"### Type IIB fibers have the most potential for growth. "

** Yeah and you also have the fewest of them. If you didn't bodybuilders would long ago have figured out that ballistic training would give them the most size. If size is your goal, training type IIB would not be your best choice.

### I would disagree, hypertrophy in weightlifters usually occurs in their legs and upper backs. They tend to carry more hypertrophy there simply because of the greater amount of volume of their lifts work those muscles. Powerlifters will often have comparable upper backs and much larger chests, but rarely is their leg development comparable to a weightlifter of the same weight class. Also, despite the weight class more powerlifters use methods that improve maximal strength (i.e., strength without regards to bodyweight), weightlifters use methods that more closely follow the lines of relative strength, particularly after several years of training.

** Good points. The weightlifters upper back is hypertophied in comparision to the powerlifter simply because every lift they do taxes the back where the powerlifter does not really use their traps primarily in any exercise (a good form deadlift isn't locked out with the traps).

If type IIB fibers packed on size though, you would expect an oly lifter who trains many times a week to be bigger than a powerlifter who trains few times per week. The leg issue is hard to argue, because an oly lifter squats a lot along with doing explosive movements; but I would argue that the leg development comes from the squats which hypertrophy type IIA, more than from the explosive hip drives in the snatch and CandJ.

Study - Powerlifters and type IIB

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Re: functional hypertrohphy1
« Reply #1 on Oct 16, 2005, 7:39am »

Todd Wilson
User Question for Todd Wilson....
Sunday, October 9, 2005 7:07 PM NEW!

** Yes he uses heavy weight, however he is still a powerlifter, meaning he training for high force & low velocity movements.
### And? Exactly!

I know that their may be some plyometric effect to some of the band work Vaughn does, but the fact is he is training to lift a really big weight up without regard to speed.

### Speed has nothing to do with it. With lighter loads one must have maximal speed in order to recruit higher threshold motor units, but higher threshold motor units are also recruited with heavy weights that will be lifted slower.

Studies show that powerlifters have less type IIB fibers (1.3%) than untrained men (12%. This is because unless they are doing ballistic training (altitude landings, etc) they are still converting most of their type IIB to type IIA.

### This is incorrect. And certainly not representative of powerlifters as a whole. To assume you must have a plyometric or ballistic movement in order to recruit type IIB fibers is incorrect.

I am willing to admit Vaughns band workouts may make him a little more plyometric than many lifters, but he is still a powerlifter.

### Not sure how bands will make someone "plyometric."

** Yeah and you also have the fewest of them.

### Not necessarily, sprinters will always have a much higher percentage that the average population and particularly more so than a world class marathonner.

If you didn't bodybuilders would long ago have figured out that ballistic training would give them the most size. If size is your goal, training type IIB would not be your best choice.

### Your last statement is correct, however you are misunderstanding a couple of things. 1) Ballistic training is not the only way to recruit the higher threshold fibers. Further, ballistic training does not allow for very much time under tension which is needed for hypertrophy. 2) Bodybuilders must attempt to maximize the hypertrophy of the entire pool of motor units. A powerlifter receives no benefit from using training methods that hypertrophy the slow twitch motor units, it would be non functional.

** Good points. The weightlifters upper back is hypertophied in comparision to the powerlifter simply because every lift they do taxes the back where the powerlifter does not really use their traps primarily in any exercise (a good form deadlift isn't locked out with the traps).

### Powerlifters use their traps extensively in the deadlift, that's why the good ones don't have necks. I never said anything about the lock out, but they have to hold onto the bar, and therefore to prevent injury the traps must contract.

If type IIB fibers packed on size though, you would expect an oly lifter who trains many times a week to be bigger than a powerlifter who trains few times per week.

### Not necessarily, because of the nature of the olympic lifts they utilize fewer eccentric contractions, and their lifts are very quick therefore they do not reach optimum time under tension in order to induce hypertrophy to the extent lifters who use slower lifts do. But they clearly do posses significant amounts of hypertrophy, however they are stronger for the hypertrophy that they do have because of the motor units that they are recruiting

The leg issue is hard to argue, because an oly lifter squats a lot along with doing explosive movements; but I would argue that the leg development comes from the squats which hypertrophy type IIA,

### What do you base that on? I think you are misunderstanding the physiology or motor unit recruitment. If you performing sets of 3 reps in the squat, to think that your only recruiting type IIA fibers is just incorrect. As intensity increases the body recruits higher threshold motor untis and it recruits more motor units.

more than from the explosive hip drives in the snatch and CandJ.

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Jeffrey Vaughn
User Question for Todd Wilson....
Sunday, October 9, 2005 9:26 PM NEW!

Interesting...
Jeffrey Vaughn

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Mourad Tariq
User Question for Todd Wilson....
Sunday, October 9, 2005 10:30 PM NEW!

### This is incorrect. And certainly not representative of powerlifters as a whole. To assume you must have a plyometric or ballistic movement in order to recruit type IIB fibers is incorrect.
- Why is this incorrect? How is the study I posted flawed? It's not that I don't want to believe you, but I just have a hard time trying to believe that every study I have read, every world class sprint coach, is wrong.

World class sprint coach Hakan Andersson wrote: "It seems an undisputed fact that most (all) types of resistance training are pushing MHCIIX toward IIA and the only stimuli that really changes the different MHC proteins toward a faster character is rest."

Charlie Franics maintained that sprinters are converting all muscle fibers toward type IIA, and that every olympic sprinter has type IIA predominant.

Everything I tend to read seems to point toward ballistics being the only possible way to convert fibers to type IIB. I may have been misleading before, I am not arguing that intenses powerlifting does not hypertrophy type IIB fibers. I am just arguing that it does not convert IIA to type IIB, but it DOES convert IIB to IIA, so the net effect is more IIA and less IIB.

I just want to know if all these people are wrong? Is there new research that says otherwise? I haven't read it, would you link me to it?

"** Yeah and you also have the fewest of them.

### Not necessarily, sprinters will always have a much higher percentage that the average population and particularly more so than a world class marathonner. "

- YES, but I wrote you have the fewest of them, and you responded with percentages across groups. I said humans do not have as much IIB as other types, not that some dont have higher percentages than others. Fact is humans are humans, sedentary slow twitch animals, no matter how you train you don't turn into a jackrabbit.

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Todd Wilson
User Question for Todd Wilson....
Monday, October 10, 2005 12:10 AM NEW!

Why is this incorrect?
### It's incorrect that powerlifters are "converting most of their type IIB to type IIA." What would the physiological basis for assuming this be. Your study was just an abstract, but it did not conclude that did it? Or did I miss something?

How is the study I posted flawed?

### I didn't say it was, but it really doesn't support what you are saying, besides it only test 5 powerlifters. Because of the wide range of fiber distribution, any study looking into fiber distribution needs a lot of tests subjects for the most objective results.

It's not that I don't want to believe you, but I just have a hard time trying to believe that every study I have read, every world class sprint coach, is wrong.

### Well, what studies have you read that indicate that a movement must be dynamic or ballistic in order to recruit type IIB fibers? Those fibers are recruited at high intensities of contraction. Even if the contraction is isometric.

World class sprint coach Hakan Andersson wrote: "It seems an undisputed fact that most (all) types of resistance training are pushing MHCIIX toward IIA and the only stimuli that really changes the different MHC proteins toward a faster character is rest."

### I'm not sure if I understand this, I would have to see it in a broader context.

Charlie Franics maintained that sprinters are converting all muscle fibers toward type IIA, and that every olympic sprinter has type IIA predominant.

### I think you may have type IIA and IIB fibers confused. Type IIA are the intermediate fibers.

Everything I tend to read seems to point toward ballistics being the only possible way to convert fibers to type IIB.

### Well hold on, we have not been discussing conversion. Frankly, there is a lot of talk about conversion right now in research circles and more strength coach/personal trainer authors are picking up on it and the information around the web is poor at best, and the understanding of what conversion is, if it takes place, and how it happens is largely unknown. If you want to discuss it, fine, but it needs to be discussed in and of itself. But frankly, the programs and authors writing them that are talking about "train this way and convert your fibers" are full of bull. They have a poor understanding of the physiology behind motor unit recruitment.

I may have been misleading before, I am not arguing that intenses powerlifting does not hypertrophy type IIB fibers.

I am just arguing that it does not convert IIA to type IIB,

### Well, it's debateable that this can be done period.

but it DOES convert IIB to IIA, so the net effect is more IIA and less IIB.

### I have not seen any evidence that powerlifting or any other training for that matter will convert type IIB fibers to type IIA.

I just want to know if all these people are wrong?

### Well, I'm confused as to what all people you think are right.

Is there new research that says otherwise? I haven't read it, would you link me to it?

### Well, I thought we were talking about fiber recruitment, not fiber conversion. For one thing, many who discuss fiber "conversion" do not distinguish between actual fiber conversion and relative fiber recuitment. Until that distinction is made any discussion is meaningless. Furthermore, while we have labeled fibers as type I, IIA and IIB for years, more recent research from Japan (if I have time tomorrow I'll try to find it) contends that there are over 40 different types of muscle fibers that exist along a continuum of oxidative capablities. That would suggest that some of the research on fiber conversion has been misguided.

"** Yeah and you also have the fewest of them.

- YES, but I wrote you have the fewest of them, and you responded with percentages across groups. I said humans do not have as much IIB as other types, not that some dont have higher percentages than others. Fact is humans are humans, sedentary slow twitch animals, no matter how you train you don't turn into a jackrabbit.

### Other types of animals? And that is relevant how?

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Mourad Tariq
User Question for Todd Wilson....
Tuesday, October 11, 2005 9:43 PM NEW!

Todd -
Physiology may not be my field, I know more about type IIB superstrings than muscle fibers, but I am NOT confused, I understand the difference between type IIA and type IIB.

### "I didn't say it was, but it really doesn't support what you are saying"

- So if the study isn't flawed, then powerlifters have a much lower percentage of IIB fibers than sedentary people. This does support what I am saying (THAT VAUGHN IS NOT A TYPE IIB DOMINANT PERSON). If this is the case there are two possibilities.

1) Powerlifting training converts fibers away from IIB nature and toward IIA, in which case Vaughn, as a someone who engages in this training would have less IIB than most people.

2) Powerlifters are selected to have more IIA and less IIB than most people. If this is helpful, then again I would argue that Vaughn, as a successful powerlifter probably has a similar fiber makeup to the type of make up that is needed.

- Its like the question of whether olympic lifting makes people run fast and jump high. Olympic lifters can run fast and jump high. This means either their training causes it, or people who already could run fast and jump high are the ones who succeed in oly lifting.

###....Furthermore, while we have labeled fibers as type I, IIA and IIB for years, more recent research from Japan (if I have time tomorrow I'll try to find it) contends that there are over 40 different types of muscle fibers that exist along a continuum of oxidative capablities. That would suggest that some of the research on fiber conversion has been misguided...

** I have read this research, and while it does hurt the notion of a discrete conversion, and doesn't mean characterstics of a fiber can't change (in fact this is a much easier argument to believe) and then at some level I would argue the characteristics of a powerlifters fiber would change toward the IIA part of the continuim and away from the IIB part which is movements that require much more speed the powerlifting.

Finally- I will try and dig up some more studies to support what I have been told by many leading authorities and have read in scientific journals. I would actually like to believe that you are right as it allows one more freedom to change their performance. I'd just like to see some studies that show how powerlifters have a greater percentage (not amount) of IIB type fibers than average people. Even an article that said that about sprinters would be interesting.

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Todd Wilson
User Question for Todd Wilson....
Tuesday, October 11, 2005 11:46 PM NEW!

- So if the study isn't flawed, then powerlifters have a much lower percentage of IIB fibers than sedentary people.
### You can't say that based on a study of ten people. FIber tpyes are widely varied. Just because the sedentary people had a higher percentage of fiber types doesn't mean anything. If you look at the percentages given for both groups, they are both, actually quite average. The population simply isn't large enough. To suggest that this study implies conversion would be a giant leap of logic.

This does support what I am saying (THAT VAUGHN IS NOT A TYPE IIB DOMINANT PERSON).

### To quote myself: "Well first, understand this is more of a facecious joke than a declarative factual statement." Without a biopsy, or at the very minimum some muscle testing neither one of us can definitely say what Jeffrey's fiber make up is like. However, given the manner in which he trains, his physical abilities, etc. one can assume that Jeffrey has a high percentage of fast twitch fibers. He may not! He may be a "slow twitcher: and just a freak of nature, but the assumption based on those inferences will hold in a lot of cases.

If this is the case there are two possibilities.

1) Powerlifting training converts fibers away from IIB nature and toward IIA, in which case Vaughn, as a someone who engages in this training would have less IIB than most people.

### Again, I have see zero evidence to support this. From either an empirical stand point or even a theoretical standpoint.

2) Powerlifters are selected to have more IIA and less IIB than most people. If this is helpful, then again I would argue that Vaughn, as a successful powerlifter probably has a similar fiber makeup to the type of make up that is needed.

### I would say "selected" is a poor choice of words. 'Tend to have,' maybe, but your study done on 200-500 people would be much more interesting, as this would unequivocably give use a generalized median of fiber types.

- Its like the question of whether olympic lifting makes people run fast and jump high. Olympic lifters can run fast and jump high. This means either their training causes it, or people who already could run fast and jump high are the ones who succeed in oly lifting.

### Not really, because you can keep records and verify performance improvements based on training. However, No Kenyan has ever won an Olympic medal in weightlifting.

** I have read this research, and while it does hurt the notion of a discrete conversion, and doesn't mean characterstics of a fiber can't change (in fact this is a much easier argument to believe)

### This is more along the lines of what available research suggest, however, some of the studies looking into characteristic changes do not take into consideration intermuscular and intramuscular coordination. Since Jeffrey's been our guinea pig, let's continue to use him....even if he were predominately slow twitch, he clearly possesses great intramuscular coordination and intermusclar coordination at least to a proficient enough degree.

and then at some level I would argue the characteristics of a powerlifters fiber would change toward the IIA part of the continuim and away from the IIB part which is movements that require much more speed the powerlifting.

### Please expound on your logic here.... Personally I'm not convinced either way yet, I do think that altered characteristics is plausible to an extent, but to what extent and to the actuality of it, I'm not sure yet. However, if we accept that fibers can change characteristics, it would make much more sense for the powerlifter if the fibers converted from type IIA to type IIB due to their training, and in fact I believe that this would be more likely than IIB's converting to IIA's simply because of their oxidative capacities. I do not think that the cellular structure of IIBs allow them to "develop?" the mitochondria in order to allow them to act as IIA's however with high intensity training, it is theoretically plausible that the IIAs lose some of their oxidative capacities via a lowered amount of mitochondria in the cell of the IIA fiber. Perhaps, the actual number of mitochondria are not lowered, but because of non use, the inner membrance would potentially become less folded, as is seen in sedentary individuals as opposed to aerobically fit individuals, but I'm not positive that this would happen. Further more, again, you seem to want to think that IIBs are only used during "fast" movements. This is clearly not the case. As intesnity increases so does the recruitment of high threshold motor untis (i.e., IIBs); Intensity is increased by speed of movement and/or resistance.

Finally- I will try and dig up some more studies to support what I have been told by many leading authorities and have read in scientific journals.

### Well, I keep up with the research on this topic fairly closely as it has all sorts of potential ramifications, but again most of the research is very inconclusive right now. And other research is just too far removed from the athlete to even hypothesize anything. For example, one study a former professor of mine was involved with actually found conversion possible in rat muscle tissue, but the tissue was from a dead rat, and had been cross innervated. It's 300 years before we can start re-innervating athletes muscles with the nerve cells for specific task.

I would actually like to believe that you are right as it allows one more freedom to change their performance.

### Well, performance can be changed, and drastically. But, I just don't think a Kenyan is going to win the 100 meters anytime soon or that someone built like Bill Kazmier is going to win the Boston Marathon.

I'd just like to see some studies that show how powerlifters have a greater percentage (not amount) of IIB type fibers than average people. Even an article that said that about sprinters would be interesting.

### Well, understand, the "average" sprinter or powerlifter is going to be comparable to the average person. Say 75% of the population. But, those that succeed succintly on the world class level, are going to be a little different. For example, It's hard for me to believe that Carl Lewis was anything but a guy with a bunch of fast twitch muscle fibers. He had great technique, yes, but he could outrun most people backwards. Sure, someone with average fibers types may reach the tops of their sport from time to time, but Let's say you take the top 100 powerlifters (sprinters, shot putters, weightlifters, etc) of all time, you have to assume, that the majority of them have a little genetic help in the area of ideal fiber typing for their sport. Likewise, while a guy/gal with average fiber distribution may occasionally excel at an aerobic sport, I've got to think Lance Arm strong has an ass full of highly oxidative slow twitch fibers with maxed out mitochondria in each cell. I can't except him being average, otherwise through optimal training anyone can reach his performance level. I have to assume that someone in the cycling world has copied his training.

And don't get me wrong, sports performances certainly are not solely due to fiber make up, but fiber make up clearly impacts training and there is no doubting that someone with a high percentage of slow twitch fibers is more suited for aerobic sports and that people with a high percentage of fast twitch fibers are more suited for speed/strength sports.