400m-excursion, please help

I plan to run 200 and 400m in May as a part of my school exams.
The 400m need just 58,7" and the 100m 12,3" and its much easier to do some over-points, which i need, because i cant throw(pentalon).
So i plan tempos at 80-85% up to 300m and special endurance runs(max or near max) also up to 300, maybe 400m.
Normally i dont go over 200m for special endurance.

So my question: If i am a little bit more heading for the 200m and 400m; am i loosing speed for the rest of the summer season for my special event: the 100m ???

And if so: Will i get my former speed back when i am shutting down the “400m-chapter”?

You can still work on speed while working on training for the 400m. Search “concurrent approach”. You get the best of both worlds. And no, you won’t lose your speed.

i was planning to focus on speed. i wanted just make the tempos a bit longer.

I thought about fibers i.e. : If i am doing longer runs, maybe they can change their characteristics.

I remember Charlie sayin that Ben didnt like 300m endurance runs and that he felt better afterwards.
Maybe Charie can give some deeper hints on this…

Well what you are referring to are special endurance runs. I dont think that it would have any effect on your speed. Ben did use 300m for special endurance (not all the time, but I do remember reading at a time in his training when he did) and I believe it helped his times out quite a bit. Another example: Michael Johnson trained primarily for the 400, yet still ran a 19.32 200m… No speed loss there? Also ran 10.03 for 100m…

Don’t forget that the 400m is a sprint; you need speed to compete. The better speed reserve, the better off you will be. You can train concurrently and find some great results. I’m sure you’ve read over lactate threshold; check out some of KK’s example training blocks. Hardly ever do you see any rep over 350m if ever (once you get out of GPP at least).