Tucking the Tailbone in T’ai-Chi-Form Practice: Good or Bad?

by Robert Chuckrow, Ph.D.

My understanding is that the reason that Yoga and T’ai-Chi teachers tell students to tuck their tailbones is that many people have an excessive curvature of the lumbar spine. Students’ spinal posture is corrected by telling them to tuck their tailbones. That constitutes an erroneous idea, is at odds with anatomy, does not get to the root of the problem, adds an additional problem, and starts a “war” between the pelvis and spine.

In T’ai Chi, there is a saying, “han siong ba bei,” which means hollow the front and expand the back. The back referred to is not just the upper back but also the lower back, which for most people, is excessively curved inward.

Han Xiong Ba Bei Characters

The characters for han siong ba bei.

Han Xiong Ba Bei Pronunciation

The pinyin pronunciation for han siong ba bei.

An excessive curvature of the lower back often originates from heels on shoes, which lift the backs of the legs, causing the body to tilt forward (see Figure below). To compensate, the top of the body must lean backward, thus accentuating the lumbar curve of the spine (“swayback”).

Effect of Heels on Posture

The effect of heels on shoes. Note how the pelvis is thrust forward, causing the curve of the lower back to be accentuated.

An excessive lumbar curve weakens the ability of the body to exert forward force. It also causes other problems. My book, Tai Chi Dynamics, has a section on han siong ba bei and how muscular extension plays a role. I also explain, by means of force diagrams, how an excessive lumbar curve makes the body weak, how using contraction makes the body weak, but how using muscular extension makes the body strong.

Unfortunately, han siong ba bei is commonly misinterpreted by T’ai-Chi practitioners and teachers to mean “tuck the tailbone forward,” which indirectly forces the lumbar curve to be reduced. However, reducing that curve by tucking, which pits one part of the body against another, goes against the T’ai Chi principles and is a harmful way of treating the body. There is a big difference between (a) achieving han siong ba bei by sending neural messages to extend the muscles that control the lumbar curve and (b) forcing the lumbar spine into place by means of contracting muscles that are in a different part of the body.

The most basic T’ai-Chi principle is that of the separation of yin and yang. The front of the body is yin, the back is yang. The yang elements that apply are active, expanded, and convex. The yin elements that apply are inactive, supportive, and concave. Tucking the tailbone requires contracting the front, which reverses yin and yang; that is, the front becomes active (yang), and the back becomes inactive (yin). Moreover, the T’ai-Chi principles teach us not to force anything and to have every joint in its most neutral alignment. For example, the T’ai-Chi Classics say, “In any action, the whole body must be made as light and free-moving as possible, so light that the addition of a feather will be felt for its weight, and so free-moving that a fly cannot alight on it without setting it in motion.” Fixating the tailbone, pelvis, and thigh joints in an off-centered alignment is, to me, antithetical to the basic principles of T’ai Chi.

The correct way to work on a person’s excessive curvature of the spine is through exercises that reveal to the person that he/she is using a lot of force to sustain the excessive curvature. Once that habitual force is released, the spine gradually assumes its natural shape. I have successfully worked with a number of students on this issue over the years (see article). The next stage is to learn to extend the muscles of the lower back (read about muscular extension). My experience is that most people are incapable of achieving han xiong ba bei without quite a bit of instruction and practice.

Whereas it is important to be able to attain a state of han xiong ba bei when it is needed for exerting a large forward force, doing the form in a such a continued state of extension has no purpose because you are not exerting a large force on another person. The natural lumbar curve is appropriate for standing and locomoting, as occurs in the movements of the T’ai-Chi form. Holding the body in a state of unnecessaty tension is a fixation, which is also against the T’ai-Chi principles. Instead, in doing the T’ai-Chi form, it is only necessary to allow the pelvis to float and the lumbar curve to release naturally. Of course, those practitioners who are unable to achieve han xiong ba bei without tucking will need to retrain their thinking and learn to attain natural, released shape of their lumbar spines.

Here is a link pertaining to tailbone-tucking in which “tucking” is done by pulling the pelvis forward rather than by extending the lower-back muscles! http://www.youtube.com/watch?v=H31_SUtj4o0.

©Copyright 2011 by Robert Chuckrow

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