Fast and slow twitch muscle fibres

[Duncan]

I did a search of the forum for information on fast and slow twitch muscle fibres but surprisingly I didn't find anything. Since they get mentioned pretty frequently, could someone just clear up what they are, what the difference between them is, and how you go about converting one sort into the other (if you can). Cheers

[Tom]

ok 3 types of muscle fibre

Slow twich
Fast oxidative (type IIA)
Fast glycotic (type IIB)

Slow twitch are used for aerobic activity, they have high fatigue resistance, high oxidative capacity etc etc

Fast oxidative are used for long term anerobic active

Fast glycotic are anaerobic (what you wil use in the gym mainly)

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and how you go about converting one sort into the other (if you can). Cheers

not really possible, although i have read some evidence that there is a possibily of convertion from type 2B to type 1, i.e. if u are muscular, dont do much weight training and do alot of cardio instead you can change the ratios of fibre types. however mainly the amount of each fibre you have is genetic

[Duncan]

oh right, I was told that if you do long cardio sessions then you run the risk of changing your muscle fibres to the oxidative type and after doing so you'd be less likely to respond so well to weight training

[MartinM]

I'm pretty sure the only conversion that can occur is 2A to 2B and vice versa..........

type 1 <---> type 2 simply doesnt happen in humans. It has been shown to occur in cat muscle but that was from low frequency stimulation for 12hours a day for like 3 weeks or somthing

I have definately written this before on the forum but its probably pretty hard to find it....

I wouldnt worry too much about this kind of thing, just concentrate on stimulating type 2 fibres with heavy work but on occassions it may good to give slightly higher rep work a go as slow twith fibres do have the ability to hypertrophy.

[Tom]

ive lost it but layne norton wrote an article showing that if u do a shed load of high intensity cardio and not much weight training (or support of fast twitch muscles) then you will convert your muscles to type I,

[MartinM]

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ive lost it but layne norton wrote an article showing that if u do a shed load of high intensity cardio and not much weight training (or support of fast twitch muscles) then you will convert your muscles to type I,

INteresting, if you find it let me know cos that'd be the first time I had read about it

[Tom]

thats where ive heard it...

http://www.ncbi.nlm.nih.gov/entrez/q...&dopt=Abstract

something to do with nasa or something hehe

[MartinM]

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thats where ive heard it...

http://www.ncbi.nlm.nih.gov/entrez/q...&dopt=Abstract

something to do with nasa or something hehe

That is to do with rats though and hypokinesia (i.e. being in space with no forces on the muscles).......keep trying

[Tom]

well its something like that, it wasnt a human study as i think the old mice were subjected to near fatal levels of cardio

[Duncan]

Well thanks- looks like there's no need for me to worry unless I'm planning to stay on the treadmill for 20 hours a day for the rest of my life or anything! Cheers