order of muscle fiber recruitment

[OmarJackson]

I'm confused on how muscle fibers are recruited in most bodybuilding type sets. (4-12 reps)

Is it that first the type IIA fibers are recruited until they are all fatigued at which point the type IIB ribers come into play starting from smallest to largest, or is it the opposite way around.

the reason i asked is because i read that the largest type IIB fibers, the ones with the most potential for growth, are recruited first in a set, and then smaller fibers later on. basically it said that in order to stimulate the fibers with the most growth potential, a given set does not have to be taken to muscular failure.

 

[ballzasteel]

With any type of training type IIb fibers turn into type IIa fibers. So, if you are trained you wont have any type IIb fibers to recruite. According to the size principle, slow twitch fibers (type I) are always recruited first and as more force is demanded more fast twitch fibers (type II) are recruited to work together with the slow fibers. On the other hand, when velocities and force are high, then slow twitch fibers are actually deactivated in order to let the fast twitch fibers do more of the work.

 

[Dan]

Continuing on what ballzasteel said about velocity: you could use explosive reps in order to increase the recruitment of the type II's.

 

[jminis]

I read an article and they think there's a IIc fiber.

 

[Debaser]

http://www.thinkmuscle.com/articles/haycock/hst-07.htm

 

[cr4ytonic]

http://www.avantlabs.com/magmain.php?issueID=18&pageID=216 by Lyle McDonald

Great article on the subject and how to apply it.