Video comparison of Cheng Man Ching’s 37 Form or Yang Tai Chi (Taiji) shown slow and fast. The slow version of the form is the commonly seen public version. We practice a fast version of the form as well. This form is called by various names: the indoor form, family form, secret form or combat form. The slow version of the form comes to us from Dr. Tao Ping Siang, an indoor student of Cheng Man Ching.
This method of the form is not so much a secret as it is uncommon. Certain adjustments are made to the form to enable it to be done faster, with more obvious martial intent. These include the speed of the form, changes in the stepping method, a slight curve of the spine, addition of Fa Jin and more direct movement patterns.
Here is a video showing the first eight movements of the form performed two ways: