What groups use the ITF material, but don't use sine wave?
Dancingalone already touched on this, but I'd say there are probably more people who practice Gen. Choi's patterns without sine wave than there are who practice them with sine wave. Of course, within this group of non-sine-wavers you have a variety of practices. You get people who are basically doing Shotokan techniques but performing the Chang Hun tuls, you have people who are using a degree of "knee spring" when performing techniques but don't refer to it as sine wave, you have people who are between those two points, etc.
Grand Master Kim, Yong Soo (he was in the Army II Corp in 1960, attended the first ITF Instructors course in Seoul in 1968 and is featured priminantly in Gen. Choi's 1972 textbook and its following editions; he's the gentleman using his punch to extinguish a candle in one picture) has pointed out that Gen. Choi was already teaching sine wave in the late 1960s, but that many of the instructors he trained were hesitant to change because they were used to the more karate-esque focus on keeping the head level that they were used to from their Kwan training.
Are there varying levels of "sine wave"? I know that sounds odd, but most of the videos I have seen of the sine wave it was very "bouncy" is there a subtler version that still uses the concept but more pronounced?
Yes, there are different levels of sine wave. IMHO, much of what you see on youtube is not really all that great of an example of sine wave. It's tournament "performances" and, for whatever reason, you have judges scoring people higher the more "bounce" they have. It's like people kicking above their head when the technique actually should be directed to the middle section. It gets scored higher even though people know it's incorrect. Or should know, anyway.
Sine wave is, technically, a bend in the knee of about 30 degrees. If you're interested in how much of a bend that is try this exercise: Straighten your leg, then bend it so your lower and upper leg form a right angle (90 degrees); now undo half of that bend (45 degrees); now undo
that bend by almost half. Not much of a bend in the knee is it? And yet I have seen people perform To-San where their shin is almost parallel to the floor as they wind up for the punch on movements 2, 4, 12 and 14.
There are a few exceptions where you bend your knee greater than 30 degrees, such as when performing a circular block, but those are
exceptions.
Sine wave should be a noticable, but
subtle, movement. You can definitely reach a point where it's "too much of a good thing." Think more of Jack Dempsey's "falling step" than jumping up and down on a trampoline. It's a bit like watching a wave come in to shore.
Pax,
Chris
