elastic bands, fast twich muscle

That's simply not true. There's no piece of equipment that targets a specific mucle fiber. It's how you move the weight and what intensity (as defined in reference to 1 RM) you do it at.

Bands are fine, but have a very short learning curve and the body adapts very quickly.

Stick to compound lifts & med ball work.

I am not certain about what "elastic" bands are being used and in what way, but if, by "elastic" bands, the poster is talking about resistance bands used primarily for arm, shoulder, and core work, I think they are very effective tools.

Find Ron Wolforth's websites relating to his Combat Pitcher Program and take a look at how he uses resistance bands. He has websites for the Texas Baseball Ranch and for Pitching Central. Resistance bands are only one part of his program, but they are important. He endorses products from Oates Specialties.

TuffCuff uses resistance bands as well. As does the ASMI workout provided on the ASMI website. Indeed, I know of no complete baseball program that does not include a great deal of dynamic work with resistance bands.

isaacvanwart, you are correct that elastic bands are effective, but not necessarily in relation to the original poster's questions. Fast twitch muscle fibers fatigue quickly and therefore need to be trained in an explosive manner with an an appropriate amount of resistance (ie a load that cannot be moved for more than 15 seconds).

As you said--resistance bands are great for "dynamic" work. Dynamic work is NOT the same as explosive work!

what i did to find out some good work-outs was message people on youtube who display fast twitch muscle fibers...

example:

http://www.youtube.com/watch?v=BxfM6Tvx9DE

Serious hops right there.