All described in detail at HI.
In a similar fashion, Miyahira identified the need for scrunch including lumbar lordosis (arch lower back) and side bend (tilt) and scap dig (scap retraction/lateralABduction, not truly scap "loading" because you do not want to unload/protract or laterally ABduct...
rear hip IR's as pelvis/acetabulum turns back over weight bearing rear leg (closed chain acetabulofemoral IR/AFIR) then stays in IR via upper body pullbacks/hip as bottom of top as rear leg/femur turns forward. main change at rear hip joint (acetabulum/femur motion) at this point (while handle...
in SNF type swing terms, she is early, she adjusts by not losing the corner while continuing turning the handle. not losing the corner (keep pull backs/loading/twisting the torsion bar/torso/hip through scap/overlapping/IR in hip,etc) is what prevents any casting.
for jargon definition, see the...
regarding the "push concept":
Usually when we say the swing is a "push" it means it is not high level so the arms get over-involved in generating batspeed and the swing loses quickness and and gets longer forced into a more forward orientation along the swing arc (loss of "early batspeed")...
Good description of corner/overlap/general model/terminology here:
http://www.discussfastpitch.com/softball-hitting-technical/13734-what-does-corner-mean-you-5.html#post239288
Read posts by TBao and see his illustrations in the corner thread
(remember it's the "technical" forum)
some of the other videos on tewks AB channel are good for context such as original AHA with pujols, not getting the front foot down early, weight shift in throwing, throw and swing action, running start explanation. Colabello clips also excellent. He emphasizes keeping rear HIP closed (IR ony)...
Some good stuff here:
https://www.youtube.com/watch?v=uzT-POXUHBs&feature=youtu.be
similar throwing action seen here:
https://www.youtube.com/watch?v=jNsXF4mBP28&list=UUYwHMUIY75f7o8x1IKdxpPw
lots of good youtube videos on the AB Development LLC channel
core info from miyahira;
Are Ab Crunches Good for your Golf Swing? :: Oceanic Time Warner Cable's AroundHawaii.com
he's not a plank lover.
substitutes medicine ball for hay bale
Mickey Mantle liked hay bale (more a love hate relationship that motivated him to leave the farm for baseball)
efficient momentum transfer with reactive torque of the hips requires a significant contribution from soft tissue elasticity.
as for building core, most kids don't have the time or interest. throwing and swinging a lot is about all there is time for.
how do swing and throw motions...