One of the key principles of tai chi is slow movement. This also includes stepping and slowly shifting your weight. This idea is frequently mentioned in tai chi writings. Here is an excerpt from a book I have just started reading:
"Going a bit deeper into why Sun style taijiquan is an ideal form of exercise for people wanting to improve posture, balance and mobility we need to examine the stepping method used in Sun style taijiquan. This manner of stepping requires substantial core involvement and works the core muscle group in a way that cannot be duplicated by normal walking. ~Traditional Sun Style Taijiquan Course, Cartmell and Thome, p. 27."
To understand this, we need to understand how Sun-style tai chi is different than other styles of tai chi. It includes a follow step for virtually all steps taken during forms practice. It doesn't matter which direction you are stepping.
First, place the stepping foot down empty. Empty means no weight on that foot or leg. Full means all the weight is on that foot or leg. Slowly push off with the full leg and shift your weight onto the empty leg until all your weight is on that leg. Allow the force to spiral out of the ground from the full leg to get the dan tian moving. Allow the force to spiral down into the ground as the empty let starts to fill.
When the formerly full foot has become empty, pick it up, pull it into place, and place it empty. This is very different than normal walking where we have a final push off, almost a hop, as we step. Pull is different than push and works the core muscles. After you place the foot empty, shift a tiny bit of your weight back onto that foot as you close. Where to place the foot depends on the particular form and direction of movement.
The follow step is key for delivering energy. It happens at the close of the form. My teacher has us use the phrase "BOOM then BOSS" as a mnemonic for what happens next. We say BOOM as a trigger as the follow step touches down. BOSS means Breathe Out, Sink, Song.
Breathe Out is simple: just exhale. Tai chi forms normally have an open and close. The follow step happens during a close where you are delivering power. Exhale during the closing movement.
Sink means a couple of things. The spiral force is moving down the leg into the ground. Follow it, bend the knee a tiny bit, and lower your center of gravity. At the same time, sink the qi (Read more here.). Tighten the abdominal muscles slightly and pull in the pelvic floor. This has the effect of pulling in, or tucking, the tailbone and working the core muscles. (Read more here.)
Song means to loosen and relax. (Read more here.) As you sink, be aware of creating a little space under your arms. Sink your shoulders and allow yourself to open up a little bit. Visualize a bubble of air in the shoulder joint that expands as you sink. You can do the same thing with any other joints, like in the hands.
Just remember: BOOM then BOSS.
© 2013 Eric Borreson