Slow vs fast reps activation (detailed version)

[Fiskevatten]

Saw a video and I think I kinda confused myself, so I'm hoping to hear you guys point of view
Please correct me if I'm wrong in any sense.

The video was about if fast reps or slow reps are better.
The overall conclusion was that TUT (time under tension) was the most important factor.
However, looking at different training styles and their bodies (e.g. powerlifting and swimmers) I didn't feel that that was entirely true.
So, I started looking at muscle fibers.

- Type 1 muscle-fibers (slow twitch) are more optimized for more extended, continuous use.
- Type 2 (a + b) muscle-fibers (fast twitch) are more optimized for more explosive, short-burst use.

- Both have been proven (as I read) to grow more or less equally fast depending on workout. However, type 2 muscle-fibers have more fibers per MU and therefor give more
growth than Type 1 which has fewer fibers.

Let's say you are doing a biceps-curl as a regular gym goer, that would mean that a explosive concentric movement (short lenght) and a slow eccentric movement (long lenght)
would active the most muscle fibers for growth? Most activation for both types.

Now I compare myself doing the normal benchpress:
When I train slow heavy reps (type 1) and realy squeeze that blood in to the point of pain, I always feel my chest to become more developed and full (being able to bounce them).
Doing any kind of explosive reps seem to make them smaller and harder.
This in my bro-science make me feel like type 2 fibers (which had more fibers per mu) is incorrect and makes me smaller by look.

How do I go about this? Is it all genetic in the end what you respond better to?

I love the bodies of fighters, swimmers and dancers, and most of that is explosive and I feel like I'm getting small as f*ck doing that.
I get better respons to heavy, slow movements fullness-wise, but need a lot more food to sustain it which equal to usually more bf naturally (no aas).
However, as I understand it, Type 2 requires a lot more oxygen and ATP, so they should require more fuel in form of food than Type 1. Gah...

Sorry If I write confusing, but I hope you guys get my point.
What does science say regarding activation for growth?

[EDCG19]

I think its mostly genetics

When I train slow heavy reps (type 1) and realy squeeze that blood in to the point of pain, I always feel my chest to become more developed and full (being able to bounce them).
Doing any kind of explosive reps seem to make them smaller and harder.

I dont understand what you meant here, do you mean when you go super heavy you go slower on the lift and you try and force blood into the muscle by not stopping and even if its a slow, slow movement you're still going for lockout?

Maybe even add some bands to the power rack and work on speed that way