One of Taiji and I Liq Chuan's basic principles is to keep the crown of the head suspended (like you are balancing a book your head or are being pulled up by a rubber band from above). I've been concentrating on this particular principle recently and discovered something wrong in how I've been doing things.
The issue manifests in many places but is particularly pronounced when I'm doing Tiger Returns to Mountain Cave (at the beginning of sections 2 and 3 of the Slow Form). When I transition from Crossed Wrists to the diagonal Ward Off, I tend to end up in a somewhat shorter and narrower Bow stance than usual - this is not a bad thing in and of itself but, because the stance is more compact, it changes the relative timing of the movements of the upper and lower body when doing 'Ward Off' (and the subsequent postures of Stroke Peacock's Tail).
What happens is that I find myself having fully shifted forward before my hand motions have completed. I've been compensating for this by sinking more and this is where the problem manifests. As I sink, I also end up slouching - what seems to happen is that, as I sink, I retreat my lower back and, as I'm doing that, I've been letting my spine arch (i.e. slouch). Worse, in order to feel like my crown is suspended, I end up letting my head suspend at an odd angle which leaves my spine completely out of whack.
I first tried fixing this issue by keeping my spine completely erect and stiff during this movement - this helped but I soon realized that locking the spine is as bad as locking any of the other joints. The spine needs to be flexible yet the vertebrae also need to be lined up.
Figuring this out has been difficult and I've spoken about it with a number of instructors and fellow students. Finally, one of my instructors suggested that, when doing the movement, I should focus more on the application and the energy and less on my lower body. When I do this, it helps to straighten out the timing issue, my back stays straighter, and my eyes focus further up, which helps keep my head suspended.
I've noticed this same slouching issue crop up in various places throughout the form and focusing on the application and the energy has helped straighten out my alignment.
