Well in an effort to refine my Mae geri keagi I took some video of my kicks. Working with my Sensei several things became obvious when I analyzed what we were doing with slow motion video.
- I have seen two separate ways to wind up for the kick. Method A with the knee forward and up and the foot directly below the knee. Think 90 degree angle. Method B was to wind the foot up tight against your butt. The later is definitely better.
- Don't start moving the shoulders back before pivoting the hips.
- Don't crunch the shoulders inwards in an effort to bring up the kicking new.
So after spending some time thinking on this I believe that method "A" in item #1 contributes to a multitude of sins when performing this kick. As you bring your knee upwards with the leg hanging underneath it you are sending your momentum in a pendulum arc towards the target. Instead with method "B" your foot is tucked tight under you and shoots out straight towards the target. This directs your energy directly into the target all the way from the beginning of the wind up.

Secondly I think method "A" is more likely to have you pivot early around your hips and move your shoulders backwards past your center of gravity (CG) before your kick. Try it out. The faster you bring that new up the more your shoulders want to lean backwards. If your aware of this you might compensate by crunching down in our abs which causes you to curl the back and shoulders inwards. Now try method "B" you can engage your core from the start of the kick and bring the leg under your bum than as you extend the kick outwards and through the target the hips will pivot (see photo). Notice the nice flat plane of the back and shoulders down. Ah if my kick only looked this good!
Last item is in the pull back. I noticed that I would start dropping my knee early and this caused my foot to swing down. Instead my knee needs to remain high during the complete pull back. I think dropping the knee causes the snap back to slow down and what happens if I need to double kick. Hhhmmm...
One last thing to play with. Bring your knee up to method "A" now try and engage your hamstrings and calf muscles. Now do the same with method "B". Quite a difference.
Well I will play around with this kick for a month or two and see what comes of it.