Discussion Why are bulky muscular characters so weak in JP novels and CN novels?

could be. but there is a physical limit to that. It won't go any faster than maximum since it's a chemical-electrical reaction.
at molecular levels, there's still a physical limit
a different analogy;
you can wiggle your finger fast but you can't do the same with your arm.
the momentum is exponentially larger...

anyway, I give up since I can think of much more reasons why a giant is impossible in the first place.