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Tai Chi Dynamics

by Robert Chuckrow, June 25, 2008
Those who study Taiji know that its important concepts are frequently elusive, and, for many practitioners, much of the modern Taiji literature of substantive content is difficult to understand. The pithy written transmissions of the old masters, called Taijiquan Classics, tend to be meaningful only after one understands their underlying concepts. These transmissions seem to have been intended more for confirming understanding than for imparting it.

Originally formulated in Old Chinese, the Taijiquan Classics are very compact and poetic and can be quite mysterious when translated into Modern Chinese and then into English.

Old Chinese writing conduced more to self-development than to precision of expression but also served to preserve knowledge for insiders and to keep it inaccessible to outsiders. Consider the following excerpt from the Taijiquan Classics:

Every sentence in this thesis is important. Not a single word has been added carelessly or for decoration. [Those] without a high degree of wisdom won’t be able to understand.
—Wang, Zong-Yue

In China a century or more ago, oral teachings and elucidations of the concepts were essentially reserved for family members. Now, much of the essence of Taiji has been lost or scattered, and serious students often need to study with a succession of teachers, undergo much frustration, and frequently struggle to gain an understanding of the Taiji principles let alone an ability to manifest them.

Of course, much of Taiji needs to be experienced and practiced perseveringly in order to be understood, and words often limit this understanding (a basic Daoist concept). Whereas articulating concepts in a precise, scientific manner cannot provide a complete understanding, doing so can be of much value. It is my hope that my attempts to explain some of the Taiji mysteries by utilizing scientific knowledge, conjecture, distinctions, phraseology, presentation, and approach will help practitioners of this art develop more quickly.


Strength is essential in all martial arts.Without the implied or actual use of physical strength, there is no way that one can defend against a physical attack by a skilled opponent. In fact, without muscular action, no directed movement is possible, not even breathing or circulation of blood.

In Taiji, the cultivation and expression of strength are different from that in hard styles such as Karate and Shaolin. Also, Taiji strength is different from the customary strength used in daily life.

My first teacher, Zheng Manqing (Cheng Man-ch’ing), talked about developing “tenacious strength,” or “tenacity.” According to Zheng, “Tenacity is the resistance or tonicity of living muscles. The muscles being relaxed, tenacity cannot involve the bones. Force, on the other hand, is derived from muscles, binding the bones together into a wooden (rigid) system. Zheng is not alone in making such a distinction; the Taijiquan Classics and other writings frequently mention two corresponding terms, li and jin. Li is translated as external strength or awkward force, and jin is translated as internal strength or correct force. The character for li simply means strength, whereas the character for jin means strength that has been refined through experience (jin = li + experience). Thus, jin must be cultivated through practice over an extended period of time.

Unfortunately, too many Taiji practitioners—even experienced ones—have difficulty in understanding (let alone manifesting) jin, and they incorrectly use li in doing Taiji form and push-hands. Some practitioners use brute strength in doing push-hands, and others are afraid to use force entirely.

Both of these extremes prevent practitioners from ever developing jin. In push-hands practice, those who never use strength lose the opportunity to develop jin, and those who use brute strength usually “win” over more skilled partners, giving them a false impression of success.

The rest of this chapter attempts to analyze muscular action in a way that should reduce the time for practitioners to understand the distinction between jin and li, refine li into jin, and manifest jin everywhere in the body and at any time. The idea will be developed that in Taiji, correct strength originates primarily from muscular extension, in which muscles lengthen (rather than originating from contractive muscular action in which muscles shorten). That is, jin will be interpreted as arising from muscular extension, which is unified, is capable of being quickly modified, results in a high level of rootedness, and enhances the flow of qi (ch’i). By contrast, li will be interpreted as strength arising primarily from muscular contraction, which is localized, is difficult to modify with changing conditions, results in balance (root) being relatively easy for an opponent to break, and tends to constrict the flow of qi. Moreover, it will be explained later in this chapter that correct strength is in accord with the balance of yin and yang, whereas incorrect strength is not.

It is not that one form of strength is right in all situations, and the other is wrong. Instead, it is important to recognize the distinction between the two types and be able to use the appropriate combination in a given situation.


In physics, force is a quantity that distorts the shape of an object or changes its speed or direction of motion. More simply, force can be thought of as a push or pull. Force is measured by the amount of distortion it produces in a standard object such as a spring. Alternatively, force can be measured by noting the resulting acceleration of a standard mass on which the force is exerted; the larger the force, the greater the acceleration.

Various units are used in measuring force: The pound is used in England and U.S.A. The kilogram (which really is a measure of mass, not force, but is proportional to the gravitational force on that mass) is used in most other industrialized countries. The catty is traditionally used in China and other Asian countries (1 catty = 1.333 pounds).

The forces that we experience in daily life are either gravitational or electrical. The weight of an object is the term used for the familiar gravitational force of attraction by the earth on that object. All other forces that we experience are actually electrical (nuclear forces, which are a third type, are not experienced directly). For example, when you press on a table, the force between the table and your hand is actually the mutual electric repulsion of the outer electrons in the atoms of your hand and those of the surface of the table in “contact” with your hand. Contact is in quotes because, microscopically, the atomic particles of the table and hand never actually touch each other but exert repulsive electric forces through small distances. Similarly, electrical forces can cause objects to resist deformation or adhere to other objects.

It is important to understand Newton’s first law, which deals with the behavior of objects in the absence of force: In the absence of any external force, a stationary object will remain stationary, and a moving object will continue to move at constant speed in a straight line.

Consequently, movement against gravity and changing our motion or that of external objects is impossible without force. The bones in our bodies are moved against gravity only by the forces exerted on them by muscles. Without muscles and the forces they exert, a human body would be unable to move, breathe, or affect its environment physically.

As one trained in physics, I do not disparage the use of force in Taiji but strive to be precise when I discuss it. Understanding how force originates and is applied is of much value. In order to understand correct strength, it is productive to turn to physics, anatomy, and physiology for an understanding of muscular action and a clarification of the distinction between its two kinds, li and jin.

This article is based on Robert Chuckrow's book, Tai Chi Dynamics - Principles of Natural Movement, Health & Self-Development. The book presents an in-depth discussion of many perplexing concepts by utilizing detailed explanations, illustrations, and photographs.

Robert Chuckrow has been a Taiji practitioner since 1970 and has studied Taiji under the late Cheng Man-ch’ing, William C. C. Chen, and Harvey I. Sober. He has taught Taiji extensively and has written four other books. He currently teaches Taiji in Westchester, NY.


Really looking forward to the release of this book! I have already pre-ordered my copy. I'm fascinated by the physics and bio-mechanical principles of Tai Chi Chuan.
Anonymous – June 26, 2008, 6:58 am

This book handles the application of scientific principles of physics and physiology to Taiji movements and postures. Such a book is a welcome addition to the available collection of books about Taiji that in general do not explain the physiological and physical base of the art. Since the author has almost 40 years experience in Taiji and holds a Ph.D. in physics he seems very well equipped to deliver a clarifying book about the subject.

The book however does not live up to this expectation. The author namely has based his book for a great deal on a newly invented concept called muscular extension, where muscle bundles exert force by extending instead of contracting. He connects li or external strength with the familiar muscular contraction and jin or internal strength with the new muscular extension. Any scientific support for this phenomenon is lacking and the mechanism that he proposes is in strong conflict with both established physical laws and physiological principles.

The concept is used throughout the book and many explanations are based on it. Although the book contains several useful and clarifying sections it is interspersed with this faulty concept which makes it difficult to separate the useful from the questionable stuff. It can therefore only be recommended as reading-matter for the very critical reader.

H.J. Verbeek – August 10, 2008, 4:36 pm

Congrats to Mr Chuckrow!

David Silver – February 26, 2009, 1:23 pm

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