Snake Creeps Down: when coming from Single Whip, is it possible to open such a wide posture in order to bend the left foot almost straight ahead when squating the right one? When learning, did you feel unconfortable with the right knee?
I would appreciate some correct tips to do it or - if needed - to train some specific exercises to help me doing it.
Yes it is possible; it is relatively easy to find video of people doing it. I am not a health professional and I would not presume to give health advice, but I am an aging practitioner with knee issues and I share your concern over the posture. Squatting on that right knee can be challenging.
As I said, nothing below is medical advice; I'm merely relating some things that I do to protect my knees. Your challenges may be different, and you should consult your instructor/medical professional/tax attorney/life coach as appropriate.
I ensure that my right knee stays over my right foot as I squat. Sometimes I need to turn the right foot inward a bit before I squat; I believe this compromises the purity of the posture, but protects my knees.
I also don't squat as low as I would like to; I listen to my knee and limit my practice to what my knee informs me is realistic.
I probably won't articulate this very clearly, but in my experience it is vital to warm up the qua. The degree to which I can "open" the posture without compromising the structure of the knee joint depends heavily on the flexibility of my qua. If I want to open my posture to 90 degrees or more, I find that working to warm up and stretch my qua is more effective than working my knees. (I suspect that my knee are nearing their end-of-life; there is very little left I can do other than to avoid damaging them further)
Does that help?
To respond to Mattm.... I'm making some assumptions. for squatting single whip/snake creeps down, I actually start with my right foot just beyond the cardinal and my left leg at slightly greater than 90. In order to practice isolation, I put all my weight in my right leg and slide my left heel out as I squat. At my age if I can get three to five inches of squat I'm content. I'd love to open up the posture, further as I squat, but realistically, I'm not going to be able to create a greater than 90 degree angle between my right foot and left thigh.
(of course it is easy to get into squatting single whip; the trick is to get out of it in a controlled and safe fashion. There are plenty of postures that I can do once if I'm willing to pay an orthopedic surgeon afterwards).
Hope that helps - it is possible that I've completely misunderstood the question.
As in all Tai Chi postures, the knees should point in the direction of the toes. As the angle between the feet can vary from 90° to 135° in this posture, the knees should be very open. Only like this can you achieve a stable posture.
If the knees are pointing inward, not only will your posture not be stable, you'll overly strain your knee joints.
Why do people often turn the knees inside? Because it is easier to squat low like this. If you do it with the correct knee alignment, it is much harder to squat low, but you will have very good stability, you can even withstand a lot of pressure from the side in this position.
With "bend the left foot almost straight" I presume you mean bending the left leg almost straight. Don't do it. It might look cool but not only is it unstable, it also makes the front knee very vulnerable to kicking attacks: if the joint is locked (straight), it can easily be broken. In this way, you will have less discomfort in your right knee, because you do the posture with both legs, as you should (of course most of the weight ist still on the hind leg).
My advice: begin by practicing the posture with the upper body completely straight and don't squat down lower than you can with the knees open (pointing to the toes). With time you will be able to go lower and lower. In the end you can bend forward with a straight back and if you have practiced diligently, you might be able to pick up a coin with your mouth like Yang Lu Chan and Yang Pan Hou. :)
