In one of your posts above, you stated the following:
<<In the YCF form I'm learning presently, there is an emphasys on opening the kua in stances, and keeping some tension between the legs like a pulled bow (in bow stance, which I'll start with), back foot at 45 degrees to front, 70/30 weight distributions and you're pushing back against the back leg with the front and the front with the back (very hard for me to adjust to). >>
My guess is that you are doing all of this correctly; however, there are aspects of your wording that trouble me slightly. To the extent that I myself may be one of the sources of your wording, I think I want to add some clarifications.
First, let me state what I believe to be the Yangs’ explicit teachings for the barehand form. By the way, I think this differs slightly from what is taught for their other forms. In other words, I think these concepts are basic training requirements and not necessarily advanced training requirements. They are definitely not combat requirements.
One should round the crotch somewhat, but too much or too little are both wrong. It must be “natural.” Both knees should be held in “in line” with the direction in which the toes are pointed. This will keep the hip sockets open. All the joints should generally be kept “open,” without any special emphasis on the hip sockets. As you step forward into a bow stance, the heel of your front foot first touches the ground with no transfer of momentum. You then shift some weight to flatten the foot and “grab” the ground with your toes, but do not bend the knee much yet.
You use the back leg to thrust against the ground (Deng1) and use the front leg to prop up (Cheng1) this thrusting force. You should end up with the front knee neither in front of the corresponding toes nor behind the corresponding ankle and with more weight in your front leg than in your back leg, but mathematical proportions have not been handed down traditionally. Jerry reported in an earlier post that the Yangs once gave out 60/40 as percentages for the bow stance; however, I think he would agree that the flavor of their teaching is not numbers-oriented in this respect.
Here is what I can add from what I have heard of their teaching, from what others have said on this board, from what I have read, and from what I experience through practice. The rounding of the crotch is analogous to the rounding of the back. It involves keeping the knees oriented with the toes. As Psalchemist mentioned, it helps counteract the tendency to let the knees go inward too much, making them knock-kneed.
In the Preparation Posture, think of your body as forming a stable rectangle, whose corners are formed by the tips of your shoulders and the soles of your feet. The rectangle is also divided into two sections divided by a cross bar linking your hip sockets across your pelvis. You want to have the feeling that your pelvis is spreading and the small of the back (Mingmen) is open.
If you focus on standing with a “minimum expenditure of muscular effort,” you may tend to let your knees collapse inward, as if your legs are forming a triangle, with the pelvis at its apex. This can “lock” your legs in place and allow your bone structure to take weight off your muscles, but it goes against what the Yangs teach. It focuses on hard structures rather than on soft structures.
As you push up with your head, this pulls the yoke of your shoulders upward, while simultaneously pivoting the ends of your shoulders downwards. This procedure allows you to lengthen downward along the arms through the tips of the fingers. The arms, however, do not end up straight, but in banana-shaped curves because of the sinking of the shoulders. The backs of the wrists are oriented to the sides, again accentuating the lateral feel of the shoulders.
Having the feeling of tucking your tailbone under also helps to open your hip sockets and spread you pelvis. The rectangular feel of the space between the feet, hip sockets, and shoulders encourages lateral stability and is an aspect of “zuo3 gu4 you4 pan4” (“take care of what is left and anticipate what is right”). These are two of the Five Steps.
At this point in the form, I do not think that one feels particularly for “tension” between the legs; however I think things change at the beginning of Ward Off Left. After the Beginning/Arising Posture (“Qi3 Shi4”), the body is in the same position as in the Preparation Posture, with the same body mechanics, except for the following. Rather than extending down through the tips of the fingers, one extends downward through the seated wrists and up with the fingers. The arms are also rotated inward with the fingertips pointing forward. This seating and different orientation changes the manifestation of the bend in the arms to one that is frontward and backward, rather than side to side.
To complete Ward Off Left, you must change both feet. To get into a left bow stance, you must step out with your left foot. Before you can step out with your left foot, you must first correctly place your right foot. “To go left, you must first go right.” Unfortunately, your right foot is incorrectly oriented for a bow stance, so you must adjust it first. To adjust the right, you must first adjust the left leg. “To go right, you must first go left.” To adjust the left, you have to change it from neutral to full. You create the fullness, by emptying the right somewhat. This is the logical sequence in reverse. Let me know try to tell it in correct sequence.
At the end of the Beginning/Arising Posture (Qi Shi), just before you hands hit bottom, you change the left-right relationship between the legs so that the left leg becomes somewhat full and the right leg becomes somewhat empty. In order to change the relationship, they must first have a relationship capable of changing. They cannot be involved in independent activity, but have to be integrated in the same activity and share a free circulation of Jin. Think of it as a zero-sum game. Jin in the left leg must come from the right or else we are not talking about integrated energy.
I have seen this initial move done with a distinct and noticeable weight shift to the left, but also with little or nothing visible externally. The important thing is not so much to shift weight to the left, as to divide (Fen1) empty and full so that the left is more full than the right. For me, this means that I slightly unload the joints in my right leg into the joints of my left leg. My right leg decompresses slightly, and my left leg compresses slightly. Both legs remain springy, and this is again where “bow-like tension” might be a good image. In a similar context, Jerry once used the image of manipulating both ends of a wishbone to shift the apex to one side.
The fullness in the left can then be used to pivot the right leg, which has been correspondingly emptied. As the lumbar spine rotates to the right, the right kua should not close, since it must follow the direction of the right toes. In order not to close, the leg must rotate with the spine and will travel along with it to the 45-degree angle. In this case, you must now completely unload the left leg into the right, as you lift your left heel off the ground and bend your right knee. Fulfilling these requirements while keeping the left knee pointed towards the front ends up making the legs quite rounded, almost like you are sitting on a big ball. Again, this will make the hip sockets quite open.
The type of hip/Kua usage I have described above is rather different from what happens in a posture like Fair Lady Works the Shuttles. In this posture, there are many instances in which one must sink into the hips and leave them relatively closed. I do not recall the Yangs quite using this type of terminology, but in my opinion this is what happens during many of the pivots. The same thing happens to the hips during the Single Whip transition, until the final step in the posture.
This is all I have time for now. I hope this helps.