This guy is not fast twitch

#52
#52
Actually, the jury is still out on whether you are stuck with a certain percentage of type I and type II muscle fibers from birth. Recent studies suggest that HIT training can increase type II (fast twitch) fibers, while decreasing type I (slow). For a read on the matter, check out "Human skeletal muscle fiber type alteration with high-intensity intermittent training," published in the Journal of Applied Psycology.
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#54
#54
Here's a link discussing the general consensus that the distribution of type II fibers can be increased with exercise:http://jap.physiology.org/cgi/content/full/97/5/1591
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#55
#55
paul1454 said:
Here's a link discussing the general consensus that the distribution of type II fibers can be increased with exercise:Nature vs. nurture: can exercise really alter fiber type composition in human skeletal muscle? -- Ingalls 97 (5): 1591 -- Journal of Applied Physiology
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That's a very interesting study and you are correct -- it does appear to demonstrate that through endurance exercise one can increase the distribution of slow twitch fibers to a small degree. (32% to 36%)

It also says it is generally accepted that through strength training one can promote change within the fast twitch fibers from type IIa (oxidative and glycolytic) to type IIb (glycolytic) and "to a lesser extent changes from fast- to slow-twitch fibers" but it fails to address whether or not one can convert slow-twitch fibers into fast-twitch in a similar manner. That very well may be possible but it is not addressed.

Also the degree to which the distribution of the fibers is converted is nominal when considering the vast difference in the ratio of fast-twitch to slow-twitch fibers in distance runners v. sprinters. Marathon runners have 75% slow twitch fibers while sprinters have 75% fast twitch fiber (both IIA & B combined).

Therefore one can conclude that while training can convert some type I fibers to type II and IIa to IIb, the biggest factor in the ratio of slow to fast twitch appears to be genetic in nature.
 
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#61
#61
Sabanocchio said:
It also says it is generally accepted that through strength training one can promote change within the fast twitch fibers from type IIa (oxidative and glycolytic) to type IIb (glycolytic) and "to a lesser extent changes from fast- to slow-twitch fibers" but it fails to address whether or not one can convert slow-twitch fibers into fast-twitch in a similar manner. That very well may be possible but it is not addressed.
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Two comments. First, I think you misread a portion of the article. It did not say changes can only be made between type I & IIb. It said, "Today, it is generally accepted that exercise training can promote changes within the population of fast-twitch fibers (i.e., type IIb to IIa) and to a lesser extent changes from fast- to slow-twitch fibers."

Second, the purpose of the study discussed in the article was more focused on increasing type I fibers - the reason the change from type II to type I was discussed predominantly.

There are quite a few studies that show a change from type I to type II, but none that I could find that were free on the net.
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#63
#63
When the Doctor hits you in the knee with a rubber hammer, Is that your twitch? I hardley kick at all. My brother will kick the Doctor and he's alwayse been much faster than me.
 
#64
#64
paul1454 said:
Two comments. First, I think you misread a portion of the article. It did not say changes can only be made between type I & IIb. It said, "Today, it is generally accepted that exercise training can promote changes within the population of fast-twitch fibers (i.e., type IIb to IIa) and to a lesser extent changes from fast- to slow-twitch fibers."

Second, the purpose of the study discussed in the article was more focused on increasing type I fibers - the reason the change from type II to type I was discussed predominantly.

There are quite a few studies that show a change from type I to type II, but none that I could find that were free on the net.
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No, I understood that. While it may be true that there are a portion of fibers that may be converted one way or the other depending on how you train them, that appears to be only a fraction of the percentage of fibers in the muscles. Most is left up to genetic determination.
 
#66
#66
Sabanocchio said:
No, I understood that. While it may be true that there are a portion of fibers that may be converted one way or the other depending on how you train them, that appears to be only a fraction of the percentage of fibers in the muscles. Most is left up to genetic determination.
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Samoans are not fast twitch.
 
#68
#68
Lets look at the animal kingdom....

Birds are different.... those that migrate have more dark meat.

Those turkeys that we will eat before we beat KY this year are more white meat since they can't fly anymore..... heck they can't even get it up enough to breed naturally anymore.

:question:
 
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