Are you dominated by Slow-Twitch or Fast-Twitch Muscle Fibers?

[davidjr74]

Are you dominated by slow-twitch muscle fibers or fast-twitch muscle fibers. I think its important to know this because knowing what type you are gain help you train better. Bodybuilding.com - Nick Nilsson - Training To Maximize Your Muscle Fiber Types! Genetics is the primary reason for whichever muscle fiber you are. Take the test...

1.) Take 80% of your max bench or squat.
2.) Do as many reps as you can (no caffine, creatine or anything like that before the test, pre-workout nutrition is fine though)

If you get 0-5 Reps you are dominated by Fast-twitch muscle fibers. Doing 5x5 programs, 3x5, singles, doubles, triples would benefit you the most in your training. You were made for quick reaction and explosion. Also pretty good at maxing out.

If you get 6-9 reps you are equally dominated by both. You can make equal gains during a hypertrophy phase, power phase, etc...

If you get 10 or more reps you are dominated by Slow-twitch muscle fibers. Doing 3x10, 2x15 wil benefit you the most. You were made for endurance activities. You are also good at cranking out those extra reps.

Myself, I managed to bench 128 pounds (max is 160) for 12 reps. Guess it explains why 5x5 never worked for me.

So what are you? Dark Meat or White Meat.?

 

[LeiYunFat]

I think experience has a lot to do with this. The test might work for an experienced vetran lifter, and maybe for an intermediate lifter, but I don't think it'd be very accurate for a beginner.

 

[Xab]

I'm definatley a fast twitch type. A good chunk of my cardio is spent playing Dance Dance Revolution on Heavy and Challenge (the two hardest settings) and that's like full-blown all out sprinting for 90 to 120 seconds, depending on the song. It's fun, but man it's a workout.

 

[Streamline]

Deffinately fast. I was always a top sprinter as a kid (competing at a state level). I've also adapted to gaining size quite easily since i started lifting.

 

[Karky]

yeah, beginners usually hit more reps on their x% 1rm than an experienced lifter. Actually, im pretty close to the standard charts, atleast on the bench. Anyone know if this varies alot from muscle group to muscle group? Cuz for deadlifts i think my max is way higher than its "suppose" to be

 

[buzz]

havent posted the full article just this part.

Isolating fiber types in training.


Forget about the notion of isolating fiber types while training for hypertrophy. You can't isolate fiber types per se when lifting a weight sufficiently heavy to cause muscle growth. Let me explain. Your brain activates muscle fibers in a specific sequence and manner based on the kind of movement it desires. This progressive activation of muscle fibers is called recruitment. Small "motor units" (motor neuron-muscle fiber unit with a low threshold of activation) are activated first to produce precise movements. These small motor units use slow-twitch fibers.

If activation of the inductive small motor units is insufficient to produce the desired movement, the brain activates progressively larger and higher threshold motor units. These larger motor units involve fast twitch fibers.

So, slow-twitch fibers are recruited first, followed by fast twitch fibers, based on the needed amount of strength (force or power). Because of this recruitment pattern, you could theoretically isolate small slow-twitch fibers, but you couldn't isolate fast twitch fibers because your brain activates slow-twitch first during any contraction. The greater the force of contraction, the greater the number of fast twitch fibers will be activated, but only after all slow twitch-fibers are activated.

So picture in your mind a dial that goes from 0 - 11. The numbers indicate how much force you want the muscle to generate, 0 being none and 11 being maximum intensity contraction. ON the dial, going from 1-5 the body will activate an increasing number of small motor units (slow twitch fibers) until it has activated them all. From 5-11, the small motor units will remain activated, but the body will add to them, large motor units (fast twitch fibers) until the desired muscular force is achieved. You progressively fine motor control as the amount of force goes up. This is a manifestation of the recruitment pattern just described.

Fiber type and muscle hypertrophy

Both slow twitch and fast twitch fiber are able to hypertrophy when exposed to overload. In a study by Hortobagyi, muscle fiber size of the quadriceps were compared after 36 sessions (12 weeks) of maximal isokinetic concentric or eccentric leg extensions. Type I fiber areas did not change significantly, but type II fiber area increased approximately 10 times more in the eccentric than in the concentric group.

There is a tendency for fast twitch fibers to experience more damage from training, thus fast twitch fibers tend to hypertrophy "more readily" to heavy resistance exercise. Nevertheless, both fast and slow twitch fibers hypertrophy. If you look at a bodybuilder's cross section of muscle fibers, you will find both fiber types hypertrophied, this being due to the inclusion of both concentric and eccentric contractions under load.

In conclusion fibers are classified into two different types, fast and slow. The distinction between the two types of fibers is based on both their contractile properties, as well as their metabolic properties. Slow twitch fibers, associated with small motor units, are activated first when a effort is applied against an object. Once all small motor units have been activated large motor units, involving primarily fast twitch fibers are activated.

All exercises performed by a person trying to build muscle are, of necessity, performed using sufficient weight to activate all slow twitch fibers and most fast twitch fibers. Both slow and fast twitch fibers will then hypertrophy. Fast twitch fibers will hypertrophy first, and to a greater extent, due to their susceptibility to cellular micro-trauma during the eccentric portion of every rep.

When trying to grow muscle, it is worthless to try to adjust the program to "stimulate" or "isolate" any specific type of fiber. Recruitment patterns involved in lifting weights heavy enough to cause hypertrophy activate all fibers, both fast and slow.

References:

Cope, T. C, and M. J. Pinter. The size principle: still working after all these years. News Physiol. Sci. 10: 280-286, 1995

Hortobagyi T, Hill JP, Houmard JA, Fraser DD, & colleagues. Adaptive responses to muscle lengthening and shortening in humans. J. Appl. Physiol. 80(3): 765-772, 1996


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About the Author

Bryan Haycock M.Sc. is an exercise physiologist and NPC judge. Bryan has been bodybuilding for over 20 years and holds certifications with the NSCA, ACE, and is a member of the American College of Sports Medicine. Bryan is currently the Editor in Chief of ThinkMuscle.com and is the founder and CEO of LifeStyleMgmt.com. Bryan is a highly sought after authority on the physiology of muscle growth and fat loss. Bryan also specializes in the management of type-II diabetes through diet and exercise.

 

[Karky]

Yeah, buzz, that is true. I dont know what you were trying to prove with it though? Some people are fast twitch and some are slow, some of it is genetic, but a muscle can become more slow if you train it that way.

One thing wasnt mentioned there, and that was fast lifting. If you do lets say 8 reps max for the bench press, in the beginning, not so many fast twitch are recruited, am i right? because its not really heavy, but when the last reps that you really have to force out comes, thats when most of the fast twitch fibers are recruited, and since they have the most potential for growth, people tend to say that its the last few reps of a set that makes you grow. Though, if you do the first easy reps FAST, you will recruit more fast twitch fibers, since slow twitch fibers wont be fast enough to move the weight as fast as you want to move it.
Dont know if that made any sence

 

[buzz]

well basicly this is saying you cant train by fibre type because once you get to about 80% of your rep max all fibres are contracted anyway.

 

[Karky]

yeah, thats true. So you were arguing that using 80% load aint a good way to find out? that you should rather do something like 70rm and test how many reps you get?

 

[buzz]

You can't isolate fiber types in training for hypertrophy (or strength for that matter). All the notions of training for different fiber types is a misunderstanding of how muscle fibers are activated, or recruited.

Slow twitch fibers are activated first, followed by fast twitch fibers in any muscle contraction. This is a function of small "motor units" (slow twitch fibers) being activated first for small precise movements/contractions of low force, followed by large motor units (fast twitch fibers) for large and powerful movements of relatively high force. All fibers are generally activated in a muscle at 85% of 1RM, but this may actually be as low as 50% of 1RM for some muscle groups.

So the argument about training specifically for different fiber types is wrong from the very foundation. It is simple misinformation based on a lack of understanding about motor units and their recruitment patterns. What those programs you have come across aimed at training for specific fiber types are actually doing is training for different metabolic pathways (e.g. ATP>Glycolytic>beta-oxidative).

In order to make a muscle grow you must apply high forces. This requires high loads. This requires that the body activate ALL fiber-types/motor-units during a contraction that is against sufficient load to induce microtrauma and hypertrophy.

ANY biomechanics or kinesiology text book will explain in great detail the correct properties, functions, and recruitment patterns of different fiber types and motor units. Anyone with this basic knowledge of functional anatomy could not possibly claim that isolation of fiber types is possible with loads required for muscle hypertrophy. In essence, it would be like saying that you could rev a motor at 1,000 RPM without reving it at 500 RPM.

If you have a high makeup of slow twitch fibers, all that changes is the relative %ages of 1RM you can do a certain amount of reps with

BLADE

 

[buzz]

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...but there is still a lot of controversy over this

In response to:

"A. Jones, in particular, has argued that an individual's muscle fiber recruitment and fatigue characteristics are largely genetically determined, so that there may exist an optimal TUL for each exercise, where one's musculature receives optimal growth stimulation (30). In fact, MedX technicians often incorporate the use of a "Fatigue Response Test" as a way of finding out one's particular fatigue and fiber-type characteristics. More recently, this theme has been repeated by several other authors who contend , "that (even) the concept of double progression (increasing weight and reps) is actually mistaken. Instead one should find the signature TUL for a given person in that movement and then carry out single progression. That is, progress weight at a fixed TUL as is determined by a particular fiber type and MU recruitment pattern. Once you know the ideal TUL, single progression (increasing resistance) appears to be the way to rapid gains."

- Gus Karageorgos


I've been there done that and everybody threw a fit and said I was blind (and presumably stoopid) and that I was saying things contrary to what everybody already knows and accepts about fiber types and training.

I am addressing this very issue in the next HS:Report so I will only touch on it briefly here.

First of all, if Gus Karageorgos is "GusK", I thoroughly enjoy reading his articles. I really like the way he writes and wish he would donate something to ThinkMuscle. My comments here have nothing to do with him or his views on fiber types.

Here is a statement as simple as I can make it on fiber types and training: “All muscle fibers undergo hypertrophy with increasing loads.”

That’s as simple as I can make it. There is no need to train “according” to some presumed ratio of fiber types that one is guessing they have. Besides, fiber types (MHCs) are “induced”. The type of MHC that a given fiber produces is a result of what you make that fiber habitually do through neural activity. MHC characteristics of any given muscle are constantly changing according to what it is forced to do. So if you begin to train with higher exhausting reps thinking you are making your type-Is grow, all you are doing is creating greater type-I fiber characteristics in your muscles.

Now, I will refer people to a study that was done comparing 3 different routines. (Campos GE, Luecke TJ, Wendeln HK, Toma K, Hagerman FC, Murray TF, Ragg KE, Ratamess NA, Kraemer WJ, Staron RS. Muscular adaptations in response to three different resistance-training regimens: specificity of repetition maximum training zones. Eur J Appl Physiol. 2002 Nov;88(1-2):50-60.) They used an 8-week high-intensity training program for the legs. Workouts were performed 2 days/week for the first 4 weeks and 3 days/week for the final 4 weeks. The subjects used one of three different regimens. The different training regimens were designed to be approximately equal in volume (resistance x repetitions x sets) with the rest periods between sets and exercises adjusted according to the strength-endurance continuum. Therefore, those individuals working on the high-rep end of the continuum performed fewer sets and had shorter rest periods compared with the other training groups.

The exercises were performed in the fixed order of leg press, squat, and knee extension. After warming up:

· The Low-Rep group used their 3-5RM for four sets with 3 min rest between sets and exercises.

· The Intermediate-Rep group used their 9-11RM for three sets with 2 min rest.

· The High-Rep group used their 20-28 RM for two sets with 1 min rest.

During the study, the resistance was progressively increased as subjects were able to perform more reps in order to ensure subjects were always using their true RM for each rep range.

So what happened? Did the type-I fibers increase most in the high-rep group? Did only the type-II fibers hypertrophy in the low rep group? If you believe you must do high reps for type-I fibers to grow and low reps for type-II fibers to grow then that’s exactly what should have happened!

On the other hand, if hypertrophy is a matter of load, and all fibers hypertrophy in response to increasing load, then hypertrophy should go up as load goes up. In other words the group that lifted the heaviest relative weight should have experienced the greatest amount of hypertrophy in ALL fiber types irrespective of the number of reps (within reason). And that is exactly what happened.

Here is a breakdown of the hypertrophy caused by each rep range. [Remember, each group trained to failure regardless of RM used so muscular fatigue was equal between groups.]

High-Rep (20-28RM)
Type-I
· pre = 3894 post = 4297 (10.3% increase)
Type-IIA
· pre = 5217 post = 5633 (8.0% increase)
Type-IIB
· pre = 4564 post = 5181 (13.5% increase)

Med-Rep (9-11RM)
Type-I
· pre = 4155 post = 4701 (13.1% increase)
Type-IIA
· pre = 5238 post = 6090 (16.3% increase)
Type-IIB
· pre = 4556 post = 5798 (27.3% increase)

Low-Rep (3-5RM)
Type-I
· pre = 4869 post = 5475 (12.4% increase)
Type-IIA
· pre = 5615 post = 6903 (22.9% increase)
Type-IIB
· pre = 4926 post = 6171 (25.3% increase)

Should this surprise anybody? No! Higher loads with equivalent volume leads to greater hypertrophy regardless of fiber type. It also doesn’t surprise me that these researchers were confused by the fact that the low rep group had as much or more hypertrophy that the other groups. They too have the idea cemented in their brain that you can’t use heavy weight to stimulate hypertrophy. The strength training dogma of the past has deeply influenced even the research community with regard to hypertrophy. This has done nothing but hinder their progress in understanding it because they end up designing studies on false premises.

I’m not sure why people are so hesitant to accept the preeminence of load for producing hypertrophy. Perhaps it is that they fear not growing as fast as they think they can.

It would be of much greater benefit for people to discuss issues of fiber type with regard to muscle “performance” (i.e. strength/endurance/power). After all, the very distinctions themselves are based on how the fibers used fuel, not how they respond to load. Hence, basing predicted hypertrophic outcomes on the metabolic characteristics of a fiber will never lead anybody to a correct understanding of the mechanisms of hypertrophy.

- Bryan Haycock

 

[Karky]

yeah, we all know that. No one were saying we were suppose to train only one fiber type. I just dont understand quite where you are going with this.

taking 80% of 1rm and see how many reps you get. 6-9 is normal, if you get more, you are more slow twitch, less, you are more fast twitch. Thats what the test is based upon. Are those principles wrong?

This is just a test for fun to see where you are, if you are an endurence type of guy or strenght type of guy. Just for fun, i dont think he is saying that if you should find out you are an endurance guy that you should train for endurance. Always train according to your goals.

and about the study, they both had equal volume, so the low rep group preformed quite alot of sets, am i right? Was each set to faliure, and then lowering the weight each set so the subjects could preform the given ammount of reps for all sets? or say did they do 10x3 with the same load on each set, causing them to have a coupple of reps "in the hole" on the first sets, but reach faliure on the last set?

Regardless, and off topic, this proves the method i use, 10x3 training, which Waterbury is a big fan of

 

[matt182]

Thats right but dont forget slow oxidative, fast oxidative and fast glycolytic.

 

[buzz]

yeah, we all know that. No one were saying we were suppose to train only one fiber type. I just dont understand quite where you are going with this.

taking 80% of 1rm and see how many reps you get. 6-9 is normal, if you get more, you are more slow twitch, less, you are more fast twitch. Thats what the test is based upon. Are those principles wrong?

This is just a test for fun to see where you are, if you are an endurence type of guy or strenght type of guy. Just for fun, i dont think he is saying that if you should find out you are an endurance guy that you should train for endurance. Always train according to your goals.

and about the study, they both had equal volume, so the low rep group preformed quite alot of sets, am i right? Was each set to faliure, and then lowering the weight each set so the subjects could preform the given ammount of reps for all sets? or say did they do 10x3 with the same load on each set, causing them to have a coupple of reps "in the hole" on the first sets, but reach faliure on the last set?

Regardless, and off topic, this proves the method i use, 10x3 training, which Waterbury is a big fan of

sorry if i confused you mate i dissagree with this statement he made
(quote)
Conclusion

Training your muscles according to their fiber type makes sense. It will help you to get better results from your training by allowing you to more specifically target your training according to the exact specifications of your muscles

if you read through what i put up you will see that is not true you cant train one fibre type without the other when you hit a certain weight all fibres are engaged.

 

[Karky]

oh now i get you. sorry, i dident see the part of his post where he said that. I think he must have edited it inn after i read it, it dident bother to re-read the top post when replying to your reply, as i dident know it had been changed. Or maybe i just missed it

Your studies were more about size, right?

But doesnt a slow twitch person have better potential to get good muscular endurance than someone whos more fast twitch? I mean, most top olympic lifters are probobly fast twitch by genes, and most marathon runners are probobly slow twitch by genes. Im not saying that marathon runners gain more size by doing high reps than low reps. But wont they have better potential to high endurance? while fast twitch people have better potential to get really quick, strong, explosive.

 

[buzz]

oh now i get you. sorry, i dident see the part of his post where he said that. I think he must have edited it inn after i read it, it dident bother to re-read the top post when replying to your reply, as i dident know it had been changed. Or maybe i just missed it

Your studies were more about size, right?

But doesnt a slow twitch person have better potential to get good muscular endurance than someone whos more fast twitch? I mean, most top olympic lifters are probobly fast twitch by genes, and most marathon runners are probobly slow twitch by genes. Im not saying that marathon runners gain more size by doing high reps than low reps. But wont they have better potential to high endurance? while fast twitch people have better potential to get really quick, strong, explosive.

yes you are correct its basicly your genetic makeup of fibres if you like, but my point is there is no point in training a certain way to suit your fibre type it doesnt work like that,as long as you increase the load over a period of time all fibres will become engaged so you will get growth,its just some people are luckyer than others as far as there genetics are concerned.
if you are saying that slow twitch guys make better endurance athletes and fast twitch make better lifters then yes you are correct,but as far as gaining muscle you cant train by fibre type.

 

[davidjr74]

yes you are correct its basicly your genetic makeup of fibres if you like, but my point is there is no point in training a certain way to suit your fibre type it doesnt work like that,as long as you increase the load over a period of time all fibres will become engaged so you will get growth,its just some people are luckyer than others as far as there genetics are concerned.
if you are saying that slow twitch guys make better endurance athletes and fast twitch make better lifters then yes you are correct,but as far as gaining muscle you cant train by fibre type.

Actually, to gain muscle you need to repair as many fibres as you can. So if your 80% Fast-twitch muscle and your training in the high reps, low weight area, your not going to make the gains that you should because you will be mostly repairing and growing your slow-twitch fibres, which in that case only make up 20%.

That doesn't mean you should only train in high-reps if your slow-twitch or low-reps if your high-twitch and such; but more emphasis on your lifts should be geared toward your fibre types.

yeah, beginners usually hit more reps on their x% 1rm than an experienced lifter. Actually, im pretty close to the standard charts, atleast on the bench. Anyone know if this varies alot from muscle group to muscle group? Cuz for deadlifts i think my max is way higher than its "suppose" to be

Yes, certain muscles will have more slow-twitch then fast-twitch and vice versa, most people should have slow-twitch muscles in the calves for example.

 

[buzz]

sorry mate but i dont agree with the statement that your training should be geared towards fibre type.

Both slow twitch and fast twitch fiber are able to hypertrophy when exposed to overload. In a study by Hortobagyi, muscle fiber size of the quadriceps were compared after 36 sessions (12 weeks) of maximal isokinetic concentric or eccentric leg extensions. Type I fiber areas did not change significantly, but type II fiber area increased approximately 10 times more in the eccentric than in the concentric group.

There is a tendency for fast twitch fibers to experience more damage from training, thus fast twitch fibers tend to hypertrophy "more readily" to heavy resistance exercise. Nevertheless, both fast and slow twitch fibers hypertrophy. If you look at a bodybuilder's cross section of muscle fibers, you will find both fiber types hypertrophied, this being due to the inclusion of both concentric and eccentric contractions under load.

In conclusion fibers are classified into two different types, fast and slow. The distinction between the two types of fibers is based on both their contractile properties, as well as their metabolic properties. Slow twitch fibers, associated with small motor units, are activated first when a effort is applied against an object. Once all small motor units have been activated large motor units, involving primarily fast twitch fibers are activated.

All exercises performed by a person trying to build muscle are, of necessity, performed using sufficient weight to activate all slow twitch fibers and most fast twitch fibers. Both slow and fast twitch fibers will then hypertrophy. Fast twitch fibers will hypertrophy first, and to a greater extent, due to their susceptibility to cellular micro-trauma during the eccentric portion of every rep.

When trying to grow muscle, it is worthless to try to adjust the program to "stimulate" or "isolate" any specific type of fiber. Recruitment patterns involved in lifting weights heavy enough to cause hypertrophy activate all fibers, both fast and slow.

 

[davidjr74]

Good Post Buzz.

 

[matt182]

yes you are correct its basicly your genetic makeup of fibres if you like, but my point is there is no point in training a certain way to suit your fibre type it doesnt work like that,as long as you increase the load over a period of time all fibres will become engaged so you will get growth,its just some people are luckyer than others as far as there genetics are concerned.
if you are saying that slow twitch guys make better endurance athletes and fast twitch make better lifters then yes you are correct,but as far as gaining muscle you cant train by fibre type.

Im not sure what your trying to say. As much as fast and slow twitch is gentically predetermined, it is possible to to alter the amount of certain metabolic properties of these fibres from (which i havnt heard mentioned in this thread yet) a predominant oxidative capacity to a more glycolytic capacity, and vise versa. Noting that the glycolytic fibres are larger and are able to work without oxygen whereas the oxidative fibres posses more capillaries and mitochondria, and therefore dont produce lactic acid.