I am trying to work on my fast twitch muscles, i know alittle bit about them. I am a 400 and 800 meter guy and i also run XC (5k) and i would like to work on my kick in the 5k and just work on speed in the 400... what are some good things to do that build these up and make them fast??? My track coach already has me doing box jumps and the ploymetrics stuff... WHAT WILL WORK GOOD???