For core/ back in my routine, I do a combination of the following exercises (but not all of them in a single routine):
Body Levers
Ab wheel rollouts
Seated pike/ straddle isometric holds
Seated pike/ straddle lifts
Now how effective are seated pike/ straddle leg lifts or isometric holds for moves such as press handstands or russian lever?
How long does it take most people to have their knees near their face?
Thanks