©2018 Holly Sweeney-Hillman, Yang Family Tai Chi Senior Instructor, Center Director

Bedminster/Montclair New Jersey

“The footwork in Yang Family Tai Chi Chuan is similar to that of a cat walking on a thin sheet of ice. When stepping, the foot touches the ground gently so as not to break the ice. When stepping forward into bow stance, the heel touches first, followed aby the ball, and finally the toes. Set the heel down in such a manner as to be able to easily pick it up without adjusting your weight. Don’t let the heel break the ice by landing too heavily! As the weight shifts forward from the heel to the bubbling well (yong chuan) the toes grab the ground slightly, like a cat’s claws. Once the toes are grabbing the ground, the knee bends following the direction of the toes, and the weight of the front foot shifts firmly into the bubbling well.” Yang Family Tai Chi Chuan Essentials, pg.84

As beginning tai chi students, one of the first instructions we hear is to place our weight into “the bubbling well.” This instruction is a foundation of not only our first attempts to embody the principles of tai chi footwork but it is also the foundation of tai chi’s essential principle: working with energy.

Throughout our tai chi practice, we cannot over emphasize the importance of the “bubbling well” and we should never stop thinking about its relevance as we develop our skills through practice.

As we examine the “bubbling well” of our tai chi practice, we will keep in mind two universal principles from the world of biomechanics:





This is an exciting time in the history of anatomy and biomechanics. Imaging of living bodies is possible through many technological advances like MRI and endoscopic photography. The information derived from our ability to study living structure is overturning many of our beliefs about how a living creature’s structure is developed and maintained over the course of a lifetime.

The mechanism that creates our structure from the moment an ovum encounters a spermatozoon is the same as the one that began our vertebrate history on land about 375 million years ago when an enterprising group of fishes decided to use their fins to walk rather than swim.

This mechanism is MOVEMENT.

Science has discovered that the fertilized egg is in continual, lively movement. The internal movement of the embryo drives the formation of the extraordinarily complex organism which is you or me. Looking at this microcosm of activity at the beginning of life, we see that the rhythms of life within the embryo which were triggered by fertilization will create our entire structure and will not cease regulating our structure until movement ceases at the moment of our deaths. (1)

That’s the microcosm, looking at the macrocosm, we can see the experience of moving on land rather than water created new limb structures, breathing apparatus, necks and endless modifications of vertebrate structure that present a stunning history of how movement creates structural modifications and innovations within structure over time. (2)

Even over the course of individual lifetimes, we can observe how movement shapes structure. The coach potato person develops a different structure that the active person. The tai chi person develops a different structure than the weight lifter. The weight lifter develops a different structure than the swimmer. The swimmer develops a different structure that the ballet dancer. While the basic blueprint of human structure is quite similar from individual to individual, the MOVEMENT of the individual develops his or her structure in a unique way.



“Ground reaction force” is the energy that all vertebrate animals can utilize because we live in world that includes the force of gravity. While gravity pulls our weight toward the center of the earth, the ground reaction force, in equal and opposite proportion, pushes us away. So that we can modulate these forces and use them to our advantage, land vertebrates evolved structures that could absorb as well as transmit gravity and ground reaction force. If we look at the Figure 1 photo sequence of the dog jumping, we see the dog push off the ground to transmit ground force into its spine so the body of the dog is launched into the air. Then, we see the limbs of the dog folding to absorb the force as its front paws touch the ground so that the dog will be able to stay on the ground after the jump. Without this absorption phase, the ground reaction force would bounce the dog’s body back into the air, just like a ball will bounce back up into the air after it strikes the ground. (3)

In tai chi, we term this absorption and transmission of energy “storing and sending” or “borrowing and returning”. We need the help of the “bubbling well” to do it with maximum efficiency.

If we look at the Figures 2,3,4 photo sequence of the woman jumping, we see the same use of structure that we saw in the photos of the dog jumping: the woman pushes against the ground and stiffens her body enough to transmit the ground force upward to lift her body off the ground, then she lets her body fold up to absorb the force, allowing her to land without bouncing back up into the air.

Humans use their feet to push off and transmit ground force up into their structure and also use their feet to absorb force upon landing, Figure 5 It is the amazing internal structure of our feet that gives us what is termed effective mechanical advantage, or EMA, in the lexicon of biomechanics. The EMA that the structure of our feet gives us allows us to modulate both the transmission and absorption phase to accomplish the exact motion we choose. For instance, walking uses a fair amount of stiffness in our feet

and legs so we can quickly roll our weight from one foot to another while our body is propelled smoothly forward. Jumping requires more absorbing followed by more stiffening to use the ground force to propel our bodies upward and then more absorbing to land without injury. (4)

Our feet are comprised of 52 bones and many types of strong connective tissues which form the joints that link the foot bones, connect the muscles of the lower leg to the bones of the feet, connect muscles within the feet to the bones they move, form three arches which allow us to stand upright over the relatively small surface area of our feet, and the plantar fascia bands in the soles of our feet that unify the entire mechanical action of our feet as we transmit and absorb ground force with every step we take. The structure of many bones linked together with a large amount of connective tissue gives our feet tremendous ability to absorb ground force. (5)

Looking at the microcosm of our foot structure, Fascia is the general name given to all the myriad types of connective tissue in our bodies and it is within the microcosm of our fascial tissues that the structural blueprint of our body is created and maintained from the beginning to the end of our lives. Figure 6 shows us a diagram of the extracellular fibrous chains which form a continuous “inner net” within our bodies, giving total continuity to our bodies in movement. This fibrous inner net is continually changing: when the fibrous chains are stretched, they store energy; when the stretch is relaxed, they release energy. Movement keeps the fascial chains stretching and releasing which maintains their healthy function. Lack of movement causes the chains to lose their resiliency and become less elastic. Overall EMA drops because the fascia cannot effectively store and release energy. (4)

Placing our weight into the “bubbling well” means placing our weight in an area defined by the 3 arches of our feet which are unified by the plantar fascia, Figure 7. This creates an evenly distributed stretch of the plantar fascia which elongates all three arches of our feet and extends the toes forward sort of like a cat extends its claws when it stretches its legs. It is important to understand that the “bubbling well” is a structural reality of our feet. Putting our weight into this area gives us maximum EMA for absorbing and transmitting gravity and ground force. The “bubbling well” is not a metaphysical concept, it is a physical concept based on astute understanding of the biomechanics of the human foot.

You could imagine your “bubbling well” area as a “trampoline -like” structure in your feet. When you place your weight into the “bubbling well” the whole structure of your feet expands and stores energy within the fascia; when you remove your weight the “bubbling well” rebounds, sending energy upward into your legs. Understanding the function of the “bubbling well” area of your feet helps you to appreciate why the tai chi classics state that “the energy is in the root and the root is in the feet …”

When we begin our tai chi journey, we have not had much experience with “cat walking” or developing energy storing “relaxation or extending” within our bodies. Our feet need the movement of tai chi to become conditioned to stretch and store energy, we need to develop more softness (absorption) in our footwork. Foot wear is a consideration because foot wear can prevent the natural function of our plantar fascia. Foot wear that has a raised heel or is too narrow or short in the toes will prevent the internal structure of our feet from moving when we place our weight into the “bubbling well”. Foot wear that has a heavily cushioned sole will also impede the conditioning of the plantar fascia and our feet in general. Cushioning within the sole of our shoes will absorb energy but not return it very effectively. This kind of foot wear will interfere with the natural balance of store and release within the structure of our feet. Foot wear that simply protects the surface of our feet from cuts or bruises and allows room for our foot to expand in weight bearing phase is the best footwear for tai chi practice.

Placing our weight into the “bubbling well” over and over again in our practice will condition the ability of our feet to store energy more and more efficiently because movement shapes structure. Our feet and our overall health benefit from this essential instruction: “Place your weight into the bubbling well!”


How do you know your weight is into the “bubbling well”?

“It is important to understand your whole foot takes weight. If you cannot pick up your toes without shifting your weight and if you cannot pick up your heels without shifting your weight, you are placing your weight into the correct area of your feet.”

“Also notice: when your weight is placed into the bubbling well, you will have a natural and comfortable feeling in your abdomen. Physical balance and ease of breathing go together.”

Notes from Grandmaster Yang Jun’s lecture, TTM seminar, September 1, 2018, Danbury, CT.


1. Paoletti, Serge. The Fasciae, Eastland Press, Seattle, 2006, pgs. 13-14.

2. Dial, Shubin, Brainerd, Eds. Great Transformations in Vertebrate Evolution, The University of Chicago Press, Chicago and London, 2015, pgs. 31-63

3. Dimon, Theodore. The Body in Motion, North Atlantic Books, Berkeley, California, 2011, pgs. 52-53

4. Dial, Shubin, Brainerd, Eds. Great Transformations in Vertebrate Evolution, pgs. 228-229.

5. Rinzler, Carol. Leonardo’s Foot, Bellevue Literary Press, New York, 2013, pg. 60

6. Guimberteau, Jean- Claude and Armstrong, Colin. Architecture of Human Living Fascia, Handspring Publishing, Edinburgh, 2015, pgs. ix-x.