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Expansion Underlies Everything

Tai chi (taiji chuan) is known as an “internal art” because it uses internal energy rather than external muscular force. This internal energy is developed through relaxation, internal connections, skeletal alignment, and body unity. When done correctly the resulting energy is called peng-jin, and it is in every tai chi posture and movement. For an in-depth article about peng-jin please see The Inner Connections of Peng-Jin. The essence of peng-jin is EXPANSION, and in this article, we will explore why we want to feel continuously expanded and to not shrink, and why expansion underlies everything we do in tai chi. This article is based on the teachings of my teacher, Master Ting Kuo-Piao (William Ting), and on my 40+ years of experience in tai chi.

Peng-jin is the force or energy that underlies all tai chi postures. Sometimes players confuse peng-jin the energy with peng (Ward-Off) posture which is part of the Grasp the Bird’s Tail. There is a large overlap between them because peng-jin is the energy within the Ward-Off posture. But Peng-jin is more; it is the underlying energy of all the tai chi postures and energies. It is the internal expansion of our body that connects all the parts, allows for energy to flow, and makes all the other energies possible. This is a fundamental truth of all tai chi, regardless of style, and it applies whether you practice tai chi for health and/or for martial arts.

All tai chi forms start with an opening movement; the transformation from wu ji to tai chi, which is the separation of yin from yang. This separation is how peng-jin starts. If you are just lifting your arms to start your form and there is no peng-jin or expansion in your movement, then you are missing key elements in your tai chi. Once you establish peng-jin or expansion you maintain it as you move from posture to posture, and there is never any contracting, shrinking, or collapsing. Unfortunately, 90% of tai chi players today are not familiar with peng-jin and the importance of expanding because it is very hard to find good, high level teachers who really know and understand the internal aspects of tai chi. A while back, in one of the tai chi Facebook forums, I asked, “Why do you always have an egg under each armpit?” I received more than 100 answers, and less than 10 knew that it had something to do with relaxing and hollowing the chest and rounding the back.

What is expansion in tai chi?

Expansion is the opening of all the joints and the lengthening of all our muscles. Tensing the muscles shortens the muscles and pulls on the joints to close them. When the joints open and expand, and the muscles lengthen, all the parts connect to create a unified body. It is expansion that unifies the body to create the three major bows that make up all the tai chi postures. Without the bows, energy does not flow as freely, and the tai chi postures lack resilience and power.

How do you expand?

Imagine wrapping your arms around a very large beach ball that you’re holding against your chest while relaxing all your muscles. What does your chest do? It sinks inwards to accept the ball. Your back responds by becoming rounder as your shoulder blades move further apart. To be able to wrap your arms around the ball your shoulder, elbow, and wrist joints have to separate. If you make the ball as large as your entire trunk, you will also feel your legs expand. Your hip joints separate when you bend your kwas. Your knees, ankles and eventually toe joints separate as well. Slowly, you become one with the ball; larger, rounder, connected, and unified.

Why is expansion important in tai chi?

The tai chi classics say, “There is separation within connection, and connection within separation”. Expansion separates each joint while at the same time connects the parts that make up the joint. For example, when you expand your shoulder joint you separate your arm from your trunk, yet the connection between the arm and your back becomes stronger. But when your arm is just hanging loosely at your side, there is little connection between your trunk and your arm. When you feel your body totally connect as a single unit, it’s because of the internal separation of the body’s joints.

Isn’t Relaxing Enough?

There is an assumption in tai chi that if you just relax enough everything will fall into place. To be sure, relaxation is the most important part of tai chi, but relaxation is not enough. Just relaxing does not unify the body into a cohesive unit. Relaxation without expansion is limp and lifeless. Just relaxing does not circulate enough energy to ward off attacks. For example, when doing the “Hugging a Tree” posture or pile stance, if you are relaxed without expanding, you may feel somewhat connected, but a small push on your arms will collapse you. But when you gently expand, your body fills up with strong connections that make it hard to push you.

Can You Continually Expand?

When we say, “continually expand” we mean that once you expand, you keep the expansion and you don’t shrink! It starts from the center of the body and radiates outward by gently separating every joint in our body to create space within each joint. We are like a balloon that once it is inflated it keeps its fullness regardless of how it moves. A balloon is both full and empty; although the inside is empty, it is also full. That is how our body should feel. It is only by emptying our body and creating space inside that it can be full. Some people think that you expand while in the posture and contract during the transition to the next posture. This is erroneous; the expansion is maintained as a steady state throughout the entire form. I realize that this is not easily understandable, and that the only way to really understand it is by feeling it. But it is well worth pursuing because it is what distinguishes good tai chi from bad tai chi.

Don’t You Need Yin and Yang?

Some people think that if you expand you must also contract because expanding is yang and contracting is yin. This is a misunderstanding of expansion due to thinking of expanding as only yang; only going outward. Expansion, however, includes both yin and yang because to expand there must be opposing and complementary forces. Expansion, by definition, means one part goes forward as one goes back; one part goes right, and one goes left; one goes up, and the other down. A rubber band is yin when it is static and yang when it is pulled too far. But when it is expanded, it is pulled in opposite directions having both yin and yang. Our bodies are the same; when there is no expansion, we are only yin, and when we expand too far, we are only yang. But, when we expand correctly, there is both yin and yang in every joint, in every part of our body. Some people believe that just as there is inhale and exhale there should be expansion and contraction. On the contrary, physiologically, with each exhale, our muscles relax and let go. This letting go allows the joints to open and expand a little more.

What about Push Hands?

When doing push hands does it ever make sense to shrink and allow you opponent into your space? In push hands, your opponent is looking to control your center. If you shrink you help them reach your center, but if you expand you keep them away from the center. The song of push hands in the tai chi classics says, “Attract to emptiness and discharge”. In other words, wherever you feel that there is no peng-jin or expansion, that’s where you attack. When your opponent senses emptiness in you, an absence of expansion, this is where they attack. When your opponent senses fullness (peng-jin or expansion), it feels like there is nowhere to attack; there is no weak point that they can penetrate. But, when you contract or shrink, you allow a path or connection to your center, and this makes you vulnerable. Think of any martial application of any tai chi posture. If you just do it without expanding, the force is stuck in your shoulders, or you are only using your arms. But, when you expand, you use your whole body.


Expansion is critical to the correct practice of tai chi and push hands. It unifies the body to allow energy and power to flow through the body. It is a vital part of correct alignment, and it is the embodiment of yin and yang. Without expansion, the body loses its resilience and power. Without expansion, the postures are limp, weak, and vulnerable. Think of a chain. When the chain is not extended, the links are independent of each other and do not affect one another and therefore the chain has no power. But when the chain is taut, each link is part of the whole and a pull on the first link aligns all the other links to work together as one chain. We will follow up this article with an article called Making Use of Expansion, in which we will further explain how to use expansion for health, martial arts, and push hands.

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Arlette Twersky
Arlette Twersky
Feb 01, 2023

Thank you for these very useful and well written explanations. I have begun sharing some of them on my facebook page ( and with my students. I hope that is ok with you.

Joseph Eber
Joseph Eber
Feb 01, 2023
Replying to

It is fine. I write these articles to share with the tai chi community in order to improve the quality of tai chi.


Considering a concept of “the origin of the universe due to expansion” or a concept of “the constantly expanding universe”, or the expansion of any form of life from its beginning (the seed) to its destination (the flower), from its spring to its fall, from the initiation to the outward burst of our crying/laughing, expansion seems to be the key factor.

Also your teaching revolves around it, reminding us (your humble students :) of the intrinsic sensation of expansion – expansion from “infinitely small” subatomic potentiality into “infinitely vast” universe. It allows us to sense the subtle bliss of “expansion of Tai Chi movement” born/shaped from “inside us”. Like the movement of the car – an energy expansion born from…


I think excellently described.


Alex Menard
Alex Menard
Jan 15, 2023

Great writing from an excellent teacher!

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