Posto un articolo per quanto riguarda il piede nel Taiji.
The Mechanics of The Three Nails: Develop your root. "The foot is the light switch. The hand is the bulb."— Grandmaster William C. C. ChenRooting forms the foundation of T'ai Chi Ch'uan. Your physical and energetic root, which is in your foot, provides the basis for everything in this beautiful art. By developing a steady, firm root you can begin opening the doors to its secrets.
Relaxation is the first priority for all T'ai Chi Ch'uan players. To relax into the flowing movements of the form, and to apply the moves powerfully when you need them, you need a strong base in your foot. Once the foot provides a firm, reliable base, the other parts of the body can relax and move freely and effectively. The foot itself should not be too relaxed or loose, but should give you a feeling of firm compression into the surface on which you are standing.
To root your foot, three points on the medial or inner aspect of the sole are especially useful. The first is the big toe. The other two points are on the heel and the inner part of the ball of the foot. Grandmaster Chen calls these "the three active nails" because when the foot is rooted, these three points anchor your steps like nails that penetrate the ground. The nails remain passive while you move your leg and sink your foot into place; they become active when you energize your movements.
The three nails cannot activate without the dan t'ien's compression (lower abdomen; center of gravity). Once the foot is firmly rooted on the ground, you can activate the nails by generating a very gentle compression of breath into your dan-t'ien and by envisioning where you want your hands to go. Send your thought to the nails and compress downward by gently inhaling into the dan-t'ien. The activated nails then send signals back up through the body to move your fingers, hands, or the other foot, wherever you are envisioning applied action. As you release this compression at the end of the action, exhale. Note that this breathing process is specific for practicing the form. When you are moving fast, or dealing with significant forces, the breathing process changes. (See Compression Breathing Article)
The three nails align with the weight-bearing centerline of your body, which is the line of least resistance, greatest economy of movement, and greatest power. When you initiate a movement, this line, which I call the "body vector," passes energy from the nails through the knee to the hip joint (k'ua: medial inguinal fold), through your center of mass (dan-t'ien) up your spine to end at your hands. When you are kicking, the active vector ends at the kicking foot. By focusing on the vector and keeping everything else "quiet," you can move slowly in the same way that you would if you were moving quickly while remaining very relaxed. When you need to move quickly, you have a clean line of movement trained into your body and mind and can generate power along that line.
At all times, a more passive branch of the vector extends to the top of your head. You can enliven this branch by imagining that your head is suspended from above. This keeps you from hanging your head and enables your spirit to rise unobstructed. Branches of the vector also extend throughout your body, causing you to feel open and relaxed throughout, never cramped or constricted. You can enliven these branches by thinking that your dan-t'ien is the center of a wheel while your extremities are the spokes.
Meanwhile, the three nails anchor the primary vector, enhancing your ability to root in movement. When you send your thought to the nails—specifically the second nail—your energy bounces back up through your relaxed body to your hands. One might call this "playing the foot." To develop truly satisfying T'ai Chi, I strongly recommend that you learn to play the foot.
"The 1st nail is like a rudder of a ship,
the 2nd like the engine,
the 3rd like the anchor.
The 3rd nail 'keeps the frame' (sets the boundaries)
of each move."
— Grandmaster Chen
This focus on the nails is distinct from the idea of initiating movement from the waist, as described in most English-language texts on T'ai Chi. My understanding is that the word "waist" is a common mistranslation of the term, yau-k'ua, a compound word that Cheng Man-Ch'ing used in the early 1960s to describe the hip-joint and waist combined. The yau-k'ua determines the power and quality of your T'ai Chi, but your movements don't begin there. They begin in the foot, are directed by the yau-k'ua, and are expressed in the hands. Your ch'i (intrinsic energy) must flow through your body, penetrate your bones and spine, and collect in your belly (tan-t'ien), but everything begins in your root. As you play the foot, relax, and quiet your mind, your energy will naturally flow and accumulate in your tan-t'ien.
Further, while all T'ai Chi literature acknowledges the significance of the root, conventional wisdom states that one should root in the "bubbling-well" point,which lies just lateral and to the back of the ball of the foot. The bubbling-well is the beginning of the kidney meridian in Chinese medicine. It is important for health and energy circulation, but not as useful as the root of dynamic physical action as are the three nails. Energy coming from the bubbling-well, for example, is not capable of producing the movements of T'ai Chi Ch'uan or other physical activities. You want this point to be open for health, but play your movements from the nails.
By concentrating on the three nails, and therefore keeping your weight in the inside of the foot, you can accelerate your T'ai Chi development and avoid some common injuries. The most significant of these are injuries to the knee. When practitioners let too much weight rest on the middle or outside of the foot, which I call "foot roll-out," they get "knee-wobble" which can cause stress to the knee. When turning the body while winding up, for example, do not let your foot roll out so the weight is on the outside of the foot and the big toe lifts up. Keep all three nails of the substantial (weight-bearing) foot connected to the ground with the knee directly above the first two nails. At the same time, do not let either foot pronate, or roll inward so that the outside edge lifts away from the ground. Just practice finding the most relaxed and easy alignment with gravity.
A variety of joint problems can result from ignoring foot-knee mechanics, by over-relaxation of the leg, or by sinking too low without the support of a secure root. Playing too low for your overall mechanics places undue stress on the knees and back. Rooting through the three nails first, then letting your body tell you what is your natural height to play can relieve this problem. Follow your natural instincts. As a rule of thumb: If it hurts your joints, especially your knees, don't do it.
Regarding the bow stance, it is important to keep your forward knee over the foot, primarily over the second nail, when energizing forward movements. When delivering a move, do not shift your weight or advance your forward knee. The root is already there in the forward foot, so there is no need to shift. Again quoting Grandmaster Chen, "Keep the screwdriver over the screw." When the three active nails are strongly secured in the ground, your mind and body can relax. In turn, a relaxed body and quiet mind will ease the joints, soften the muscles, and open all the vessels and meridians. This allows the inner energy to flow easily and the body to move freely, all without interrupting the root.
One practices T'ai Chi slowly for many reasons. Among them, you relax; your mind becomes quiet; you learn to correct movement flaws and develop powerful energy flow. As you learn to move slowly as if you were moving quickly, you will discover the essential mechanics for your body. Practice this and you can achieve the beautiful, fluid movement of T'ai Chi Ch'uan.