Continuing with Shesulsa's pivoting exercise and steadily increasing the reps, I've noticed something that may prove useful to others who want to take advantage of it for their own training or incorporate it into their teaching, as I plan to do now that our TKD classes have resumed after the summer break.
Since the most `performance-critical' aspect of pivoting is in the execution of turning and side kicks, I've been doing this exercise with the following components in the order given:
(i) raise the knee of the kicking leg as high as possible, with the front of the body facing the direction of the intended kick;
(ii) moving bodyweight forward onto the ball of the foot, pivot roughly 75% through the arc appropriate for the kick (the full arc being 180º for a side kick and around 100º for a turning kick) with the knee kept high and the thigh tight against the chest;
(iii) reaching the terminus of the pivot, bring the body's weight back into distribution over teh whole of the turning foot.
Parts (iv) and up would pertain to the extension of the kicking leg, but the thing that I've noticed in particular about this initial phase of the kick, which the exercise described isolates, is that in carrying out (iii), I sometime wind up in imperfect balance, so that I wouldn't be able to say `frozen' in my final position for an indefinite period of time, up the limits of my strength, tolerance for `muscle burn', etc. I've tried to figure out what I'm doing wrong when this happens, as opposed to the instances where my balance is good enough to allow me to maintain the final stationary position without any further effort.
And after trying to banish extraneous distraction, or overly conscious thinking, while I'm doing the exercise, and just trying to be aware of my body mechanics and positioning by `feel', what I've observed is that when you shift your weight onto the ball of the foot, and complete the pivot, what you've done is raised your height slightly as you've transfered the weight; you've pivoted on the ball of your foot, and then, as part of terminating the pivot, you have to lower your foot down so your heel touches the ground again, at the same time moving your weight back from the ball of the foot towards your heel. And virtually every time I've done this so I ended up in less than perfect balance, I've failed to move my weight back along the straight line connecting the center of the ball of my foot to my heel. To the extent that I've in effect misjudged the shortest path connecting these two points, I've been off balance—a very small deviation is something I can recover from in one way or another, but if the difference in angle between that line on the one hand and the path my body weight is traveling is off by very much, I will be seriously out of balance (body weight either too much to the outside edge of the foot or toomuch to the inside) at the the end and will lack all stability in my final position.
The more I try to be guided by an awareness of where the heel of my turning foot `is' in carrying out the movement, the better my %age in nailing the pivot correctly and setting myself up for the extension phase. And since, as I've observed, if I'm not in perfect balance at the end of the pivot I have no chance of executing either kick, especially a side kick, where I can hold my leg in the fully extended position at least parallel to the ground, or higher, it's crucial for
that exercise that the pivot be carried out flawlessly. The more one focuses one's awareness of body sensation on that transfer of weight downward and back to the center of the heel along the shortest line, the more likely it is one will end up in a secure position for the extension, at any speed one like, that can be frozen at the end and mainted in comfortable balance (though that also depends on the accuracy of the compensating tilt in the upper body, which is a different story entirely!)
I'm going to experiment further with this exercise during my classes and see if it will help my students develop better form in their more comlex basic kicks. Of all the things which they have trouble with, learning the turning and side kicks in perfect form is the hardest for them, I've found. Some of that is that they aren't visualizing the kicks, and the differences between them, clearly, but some of it is this question of developing balancing skills...