Following Tinman elite over the past year, Ive read alot about cv pace and why intermediate muscle fibers should be developed through cv reps. The results and improvement seems to speak for itself but I have a question on how. If intermediate fibers help improve you in races 800-5k and are sufficiently utilized in these races, then why wouldn't doing race pace reps stimulate the fibers for improvement? It would seem that either (for example) 1600m pace reps do not stimulate int. fibers so therefore a 1600m race wouldn't use those fibers and you wouldn't see improvement from stimulation of the fibers OR if a 1600m race used int. Fibers, that training at 1600m pace would stimulate the fibers and you could improve.
TLDR: If as Tinman says, a 1600m race uses intermediate muscle fibers, why wouldn't (for example) 8x400 @ 1600 pace stimulate those same fibers?
Sorry if it's incoherent, just some shower thoughts.