What is the late great Park Jung Tae explaning here?

[Axiom]

The poster of the clip claims that it's Sine Wave explained.. I submit that it's not. Sine Wave is down - up -down. Park instructs up first... and explains how this generates force.

Sounds to me like the old school mechanics of ITF striking.

 

[Axiom]

Here is the pre Sine Wave instructional:

3. Raise the body slightly at the beginning of the motion, and lower it at the moment of impact

Just like mr Park instructed in this clip.

 

[Earl Weiss]

You need to watch what he does. Not just listen to what he says. Notice that after move #1 he bends the rear knee and raises the rear heel which causes a slight drop, then he goes u and down. This diversion between demonstration and explanation continued with General Choi at the 1990 IIC which was my first in person exposure to what he wanted. I flew in a person who could do it well and asked about the initial down which was shown but not mentioned. This person was a gifted visual learner who could watch something and imitate it without seeming to go thru a conscious thought process. At first when I asked about the initial down he said "No" then as he analyzed what he did he said "Yes" but just a little.
Sometime after that course Sr. GM Sereff tells ho he was on a train platform with General Choi in Japan accompanying him as he taught IICs in several countries. As he watched him move he took note of the initial down as well. By 1994 (Next IIC I attended with him) General Choi had refined the explanation down / up / down but the motion was the same down up down as before.

 

[Gwai Lo Dan]

I'm not an ITF guy, but one thing I was theorising this week is that you have to have bent knees to generate power in a kick or punch. Or to put it a different way, if you strike starting from a tall stance with straight legs, you won't have as much power.

So now with this thread, I am wondering if the sine wave is about power at the end of the motion, or maybe,... is it also about being in a position of power for the next motion?

 

[Earl Weiss]

So now with this thread, I am wondering if the sine wave is about power at the end of the motion, or maybe,... is it also about being in a position of power for the next motion?

IMNSHO it's about flexing the knees in order to facilitate use of the entire musculature of the body, particularly the legs, to generate power in punches. You can Google Kinetic or closed chain linking to find similar stuff. Boxing books also refer to using the legs to generate power in hand techniques. The concept is not unique. The metaphor used to contrast with "Flat Wave" and "Saw tooth" wave - no up or down motion or sharp rather than smooth motion is what generates a lot of commentary.