Originally Posted by roxyboxy
3. You absolutely cannot, under any circumstance, turn a slow-twitch fiber into a fast-twitch fiber. The mitochondria of the fiber types is different, and it can no more be done than you training your iris to be green and not brown. You can elevate in a minimal way the PERCENTAGE of fast-twich fibers to a very, very minimal extent through training. A person with a naturally low percentage of fast fibers will always have a naturally low percentage of fibers, regardless of training. Fast twich fibers are NOT thick-bundle fibers (to use a lay term). One other interesting factor that plays a part is reconditioning of the Golgi reflex, which can inhibit or excite greater groups of muscle recruitment, which allows slower fibers to ACT like fast fibers due to higher collective recruitment under stress.
I have read that they hypothesize it's possible, through training, to make slow twitch fibers can be trained to behave rather similarly to FT. This may have been just speculation, though...or I may be entirely mistaken. In any event, I strongly encourage you to share your wisdom in the Training forum, for which you seem quite qualified.