Random post from T-nation-
"Best advice I can give, though it will sound like a broken record, is to squat, squat, squat and heavy if you want to improve your sprint times.
One of my favorite anecdotes related to this is from "Romo" (Bill Romanowski's autobiography). He talks about when he first started working with Remy Korchemny on speed work and Remy asked him if he was squatting.
Romo (to my surprise) said he wasn't and was only doing leg presses for lower body work.So Remy tells Romo to start squatting and after awhile, excited with his progress, Romo comes back to Remy and tells him he can squat 400. Remy answers, "Good. Now you can squat as much as my women sprinters."
Granted most of Korchemny's athletes were juiced to the gills - he was one of the guys taken down with the BALCO bust - but I think there's something to be learned there, nonetheless."