fast twitch/slow twitch

[nosmirk]

i assume that everyone has a different percentage of fast twitch and slow twitch muscles in their body (which accounts for spinters compared to distance runners)?

because the above example involves running, is it true that if you are a sprinter for example, your arm/chest/back muscles are mainly fast twitch as well?

and would having a high percentage of fast twitch muscles mean that exercises such a bench presses need to be performed at a faster speed in order to achieve better results?



update: just found this article. seems to answer pretty much everything

http://www.bodybuilding.com/fun/betteru25.htm

 

[WesCottII]

No, because while different people have different percnetages of fibres, you use fast twitch first in any excersize, because they use the ATP-CP system, which is anaerobic.

 

[Road Demon]

correction:

In the 1960’s Henneman and colleagues introduced the concept of orderly recruitment of motor units, often called the size principle, which states that motor units are recruited in order of increasing size (Henneman et al 1965, Henneman and Mendell 1981). When only a small amount of force is required from a muscle with a mix of motor unit types, this force is provided exclusively by the small S units. As more force is required, FR and FF units are progressively recruited, normally in a remarkably precise order based on the magnitude of their force output. This serves two important purposes:

it minimizes the development of fatigue by using the most fatigue-resistant muscle fibers most often (holding more fatguable fibers in reserve until needed to achieve higher forces); and
it permits equally fine control of force at all levels of force output (e.g, using smaller motor units when only small, refined amounts of force are required).

 

[Road Demon]

The fibers in “red meat” are predominantly slow-twitch (S) fibers because the force that they produce in response to an action potential rises and falls relatively slowly, e.g. with an isometric twitch response taking 100 ms or so to rise to a peak, and even longer to fall back near zero force. Muscles composed mostly of such Type 1 fibers can work for relatively long periods of time without running down their energy stores. This fatigue-resistance (FR) results from their reliance on oxidative catabolism, whereby glucose and oxygen from the bloodstream can be used almost indefinitely to regenerate the ATP that fuels the contractile process: they are aerobic workhorses

The fibers within “white meat” are primarily fast-twitch in that their force response rises and falls more rapidly. They also tend to have a different form of myosin that possesses cross-bridges which produce force more effectively at rapid shortening velocities. Fast-twitch fibers are roughly categorized into two subtypes, depending on their metabolic processes and fatigue-resistance:

fast-fatigable (FF) or Type 2B fibers which rely almost exclusively on anaerobic catabolism to sustain force output and that possess relatively large stores of glycogen (which provides energy to rapidly rephosphorylate ADP as the glycogen is converted into lactic acid -- this source runs out fairly quickly, and full recovery may take hours); and
fast-fatigue-resistant (FR) or Type 2A fibers that combine relatively fast twitch dynamics and contractile velocity with enough aerobic capability to resist fatigue for minutes to hours.

http://www.eng.mu.edu/wintersj/muscmod/nms-func-physiology/musc-fib-comp.htm

 

[nosmirk]

espi,

but wouldnt maximizing your genetic disposition mean paying attention to whether your fast twitch muscles are present in more significant proportions than the slow/intermediate twitch muscle?

lets assume you have a higher percentage of fast twitch; would it not make sense to target these specifically?

haha just wondering. thanks for the replies

 

[wolf116]

So is it possible to increase your fast twitch percentage?

 

[Warboss Alex]

So is it possible to increase your fast twitch percentage?

no, that's part of your genetic makeup.

 

[stronglifts]

So is it possible to increase your fast twitch percentage?

No.

What you can do is force muscle fibers to behave as fast twitch. How? By training your central nervous system.

 

[Road Demon]

Fast twitch has do with the size of the alpha motorneuron that inervates the muscle fiber.

Lets simply to 3 different muscle types (their are subgroups of these fyi)
based on biochemical properties. It correlates with alpha motorneuron size

SO = slow oxidative, think marathon, small size motorneuron
FOG= fast oxidative glycolytic, think 10,000 m race intermediate motorneuron
FG= fast glycolytic, think 100 m sprint big motorneuron to carry information quickly.

Fiber type is genetically determined, but their is some ability for 'fiber type conversion' by turning on or off certain genes due to specific training stess applied to the muscle.

The literature suggests that their is LITTLE conversion from SO to either FOG or FG. FG fibers can be converted to FOG fibers. The conversion of FG fibers to FOG fibers is common, ie increasing by training 'lactate threshold.'

 

[wolf116]

no, that's part of your genetic makeup.

Thats sux balls!
Explains why I could never sprint fast even though I trained extremely hard. But I was always the fastest runner on my soccer team because that is more endurance.

 

[mrRuckus]

Thats sux balls!
Explains why I could never sprint fast even though I trained extremely hard. But I was always the fastest runner on my soccer team because that is more endurance.

You can train yourself to run faster. Train the muscles themselves and perfect running technique. I've heard that the mistake most people make is that they just don't take long enough strides.

I remember reading about the NFL combines last season and if i remember right the expert speed trainer said the max you can add is about 20% over your natural. Dont know if that's true, but am absolutely certain you can train yourself to be faster to a certain point.

Don't let genetics be an excuse. For example, just because some big black guy can get to 300 lbs completely ripped and you started as a 130 lb asian kid doesn't mean you couldn't still get to be 260 lbs and torn up. It's just a bit harder for you.

 

[wolf116]

Well in my case genetics is an excuse. Because I've had running coaching and do powerlifting. And after my 20% increase I'm still no sprinter. But in long distance I can out run anyone, even though I'm 85kgs.

Some people say it's related to testosterone levels as is the vertical jump. Does Test levels increase fast-twitch muscle fibers?

 

[wolf116]

I was picked to represent my state as goal keeper in soccer. But the only reason I didn't go any further was because I could not kick for sh!t. After 6 years of training I gave up. I should see if powerlifting has improved this. Because it has improved my high jump a little bit.

Stupid slow twitch I hate you

 

[mrRuckus]

Yeah dude I have the same type of issues when it comes to hitting and throwing in softball. I spend hours learning and studying perfect technique of both blistering my hands hitting at the cages and a heavy bag at home, know i'm stronger in general than lots of other guys, but they still hit harder and throw further/harder than I can with ****ty technique, especially the damn black guys, even the puny ones, who just seem to naturally have this huge burst of power in them that you need for just one rep to throw or swing.

So now i have this beautiful perfect rotational/torque mechanics swing that still doesn't outdo their sheer powering through of the ball with their sloppy "i just walked up to the plate and swang however i felt like" linear mechanics.

 

[stronglifts]

Once again

You have 3 muscles fibers:

Type I -Type IIa -Type IIb

The fibers that have the more power are Type IIb, they also have the lowest endurance.

Type I has high endurance, but low force production.

There are other things that differentiate the fibers, but let's talk about power, that's what I saw the most discussed.

So you get born with (just an example): 60% Type I - 30% Type IIa - 10 Type IIb. So what? you're born for doing marathons?

I'd say yes. But if you don't like marathons & want to sprint, well you can force the 60% of Type I fibers to act as Type IIb fibers.

How? By training your Central Nervous System (which controls the muscles fibers).

So how would you do this practially?

1) Lots of speed work: 60-80% low rep work for several sets
2) Lots of power work: olympic lifts, pliometrics
3) Avoiding as much as possible low intensity, high endurance work (jogging,..), long stretches,...

Do this long enough, & you'll still have 60% TypeI, 30% TypeIIa, 10% TypeIIb, because that's what you were born with. However in practice, you'll be a 70%typeIIb, 20% TypeIIa, 10% TypeI (again, just an example).

I suppose that the world strongest weightlifters ever (dymas, alexiev, taranenko,...) are
1) hard workers
2) genetically predisposed to be elite: born with high TypeIIb, advantageous body type, ...

Never forget point 1.


A test
It always amuses me when I have a friend who does bodybuilding (I'm into strength training), come to my home gym. They usually lift slow vs. fast.

When I initiate them to my methods of training, I tell them to lift fast. They can't.

Then they ask me to show them how to power clean, snatch, ... I teach them. I tell them to jump harder, to pull faster. They can't.

Why? Because they are used to lift slowly. So their muscles are used to contract slowly. With the right kind of training, the central nervous system can adapt.

 

[wolf116]

thats good to know