Here's another old video of Leung Ting doing an earlier version of his "WT" Biu Tze form. In all the 180 degree turning movements, of course he shifts his stance (one foot at a time) which is one of his trademarks. But the feet only turn 45 degrees off center. In order to complete the 90 degree turn to each side, the hips complete the rotation. The waist is slightly flexible like a very strong spring. As he turns, there is torsion and release, adding energy to to the movement. It is a subtle movement, but can clearly be seen, for example, when he rapidly pivots to deliver the series of
kup jarn (elbow strikes) around 0:18-22, or equally turning back from side-facing to center with the hooking punch after the double lap-sau movements (1:38-1:48). If you watch the very slight lag between the movement of the hip, the shoulder and the fist, you can see how the stance combines with the hips and waist to add tremendous torsional power to this very relaxed hook-like lateral strike.
Finally, a few thoughts on
Futsao's Chum Kiu video showing 180 degree pivots with
no foot movement at all. It may be fast, but it could be hard on the knees and ankles. I say that because sometimes our group works out in a studio with this weird, thin carpet that grabs your feet like nothing I've ever seen. My feet act like they are glued to the floor and consequently my Chum Kiu turning ends up looking a lot like his. Sure, it works, but ...at least for me... it's a pain in the ...er
...joints! I much prefer the 45 degree foot rotation.
Then again I have bone fusions in my ankles, and damaged knees. It might not be a problem for healthy joints.