This is very interesting. I came back to interval training and competing in meets 2 years ago after a 25 year hiatus. My best races are the 200 and 400 IM. I never was a sprinter back in the day, owing mostly to small stature (although I had decent speed as an age grouper before everyone else got bigger). I'm pleased with the progress I've made this year (1:04 to 1:01 in the 100 Fly, 2:27 to 2:18 in the 200 IM and 5:25 to 5:06 in the 400 IM) but I've been frustrated with the shorter races (can't break 29 in 50 Fly and 26 in 50 Free). Do you think that it is a good idea to incorporate this kind of workout say once a week to try to reawaken fast twitch muscles and get the "feel" you talk about? BTW I did 400 ez warmup, 200 kick n/b balance, 10 X 25 all out on 3:00, 200 ez this morning and it was very challenging (and fun). Now to go and buy some finz.