Hello,
Slow negative with pause can be very interesting to master a move as well. I extensively used this approach to get the OAC for instance. But I agree with
@Jak Nieuwenhuis : isometrics are brutal ! Even "quasi isometrics" like the "2 minutes 1 repetition" principle from S. Maxwell - which is excellent by the way" is incredibly tough. By the way, I remember he advocates not using it more than 1 or 2 a week !
@Kozushi underlines something very interesting: "multi-directional". I noticed that varying the angles of the push ups (feet + hands on the floor ; feet elevated + hands on the floor ; feet on the floor + hands on a push up bar, etc...) create a well rounded muscle structure.
In fine, this transfer pretty well to real life strength. Indeed, in a fight (or whatever activity), we vary the angle a lot.
Regarding the core training we get from the OAOL PU, we can apply the same logic as well: plank (both front and side), plank with elevated feet, etc... I admit the GU gives all this in only one exercise, but if we "deconstruct" it, we can find some bodyweight patterns.
Kind regards,
Pet'