Is it better to:
1) rotate the hips and shoulders as a unit or
2) have the hips lead the shoulders slightly (twisted at the waist), then straighten the waist?

In discus throwing the waist is twisted initially, then straightened near the conclusion of the throw. The twist -> straighten movement uses muscles in the waist and lower back to add power to the throw.
Discus throwing link: http://danjohn.org/discusthrowing.html

In other words, if a bending spinal wave is useful, then why not use a twisting spinal wave?

Your question is good and I don't know the answer. I do know that Park Bok Nam teaches to keep the hips and shoulders aligned during techniques however some of his important conditioning exercises are otherwise.

I think your lable is slightly off, as the rotation around your vertical centerline and the spinal wave are diferent, seperate movements which can be done independently or combined.

Post the question on emptyflower, attention Ken Delves who is an ex-engineer and possibly buy his book as well. Should cover this, and other science and physics related ideas to internal and external(in both senses) dynamics/mechanics of martial arts.

Whether an 'intellectual' understanding of these processes will help you 'do' it for 'real'may also be open to debate.

Mech5engr,
Are you trying to push something you have already made contact with, or trying to strike something with a build up of momentum?

Are you talking about using one hand or both hands together?

Tim,

Since you posed that set of questions to Mech5engr, you've peeked my curiousity big time. Please, if you don't mind, explain differences in hip-shoulder alignment & spinal movement for:

1) Contacted, pushing, one hand
2) Contacted, pushing, two hands
3) Strike attempt build-up, one hand
4) Strike attempt build-up, two hands

Also, if you don't mind:

5) Contacted, pulling, one hand
6) Contacted, pulling 1-direction, two hands
7) Contacted, push-pulling, two hands

Thanks (as I'm just now starting to physically realize how some of this works, now's a good time for me to hear your answer -- again; did I mention I was a slow learner of things physical?).

Happy Holiday Season to the Cartmells & All Board Users.

1) Are you trying to push something you have already made contact with, or trying to strike something with a build up of momentum?

I am interested in striking not pushing.

2)Are you talking about using one hand or both hands together?

Using one hand.

3) Kenneth Delves book sounds very interesting; I will probably buy it.

4) I agree that understanding an action does not always help you perform it.

Then you would generate more power if you pre-stretch the muscle and connective tissue (just like your discus thrower).

Tim,

is the corollary to this, that if one is in contact, the greatest stability is most easily obtained with hips and shoulders aligned (essentially occupying a plane)?

Thanks,

Andrew

Andrew,
If you are in contact with someone and they are resisting (pushing back into you) with force, your (correct) alignment will lead the incoming force into the ground, allowing you to maintain balance and stability. If you should compromise your alignment, your opponent's force will immediately upset your balance and position, making you succeptable to their attack. In general, it is important to keep your shoulders and hips aligned.