The Golden Ratio - Discussing the Role of the Human Body's Center of Gravity Line in Tai Chi Attack and Defense

by langrentoh1 on 2012-02-14 16:16:46

The Role of the Human Center of Gravity Line in Tai Chi Offense and Defense

Renowned Tai Chi practitioners are often referred to as "magicians of human balance" due to their remarkable skills in push hands and practical combat. Their dexterity and subtle use of force often astonish people. This is because Tai Chi emphasizes overcoming strength with weakness, achieving great results with minimal effort, and places particular emphasis on the study of human balance. The key to studying human balance lies in understanding the body's center of gravity line. Therefore, when we practice Tai Chi, we should have a basic understanding of the human center of gravity line and its role in Tai Chi offense and defense.

(I) How to Find the Human Center of Gravity Line

The invisible line that runs vertically through the body's center of gravity is called the human center of gravity line. In upright motion, the body is supported by both legs, which maintain balance through alternating steps. It is essential to always keep the body symmetrical and balanced around the center of gravity line. Since the two legs support the body's weight differently during movement, the position of the center of gravity line will also vary. When the body stands with both legs together, the weight is evenly distributed, and the center of gravity line aligns with the central line. For example, in the preparatory stance.

When the body's legs bear uneven pressure, it becomes a virtual-real step. At this point, the central line separates from the center of gravity line. Generally, the leg bearing most of the weight is called the "real leg," while the one bearing less weight is the "virtual leg." According to mechanical principles, if the body's weight center of gravity line is located approximately one-third closer to the virtual foot between the two feet, it can make stepping firmly on the ground possible.

This "approximately one-third" can be measured more accurately using the "Golden Ratio Method": i.e., at about 0.618 from the real foot to the virtual foot; and about 0.382 from the virtual foot to the real foot. If the center of gravity line exceeds this range — either less than 0.618 or greater than 0.382 — the virtual leg will become overly weak, and the real leg may tilt.

In the final case, when one leg supports the entire body weight, the center of gravity line naturally moves vertically upward along the supporting leg.

(II) Offense - Applying Force, Tilting, Disrupting, and Destroying the Opponent's Center of Gravity Line

In Tai Chi offense and defense, if I attack my opponent, I should first find their weak points. Practice shows that directly applying force to the opponent's center of gravity line is the most effective method. Disrupting the opponent's center of gravity line equals disrupting their balance, thereby partially or fully achieving our tactical goals. Taking combined-step push hands as an example, if both parties have the right leg forward and the left leg back in a bow stance with the center of gravity forward, then both centers of gravity lines should be slightly behind the body’s midline. At this moment, if I move forward to attack the opponent, I can use my right hand as the "striking hand" and push towards the opponent's left chest. If the opponent shifts their center of gravity position, making the back leg firm and the front leg lighter, the center of gravity line moves forward. Then my "striking hand" should switch to the left hand, pushing towards the opponent's right chest. Not following these principles would result in ineffective or inefficient attacks. If I want to attack the opponent from the left or right side, causing them to fall sideways, when the opponent's center of gravity is on the front leg and the center of gravity line is slightly backward, I can turn my body to the left, using my left hand as the "guiding hand" to guide the opponent, making their front leg too solid (knee over the toes being "too much"), and the back leg even weaker. My right hand acts as the "striking hand," acting on one side of the center of gravity line, using a spiral coiling method to overturn their center of gravity line. When the opponent's center of gravity is on the back leg, their front leg becomes lighter, and the center of gravity line shifts forward. At this time, I should turn my body to the right, using my right hand as the "guiding hand" and my left hand as the "striking hand," using the same method to overturn their center of gravity line. Practical experience shows that this type of attack is concise and effective.

If, during the aforementioned combined-step push hands, my right hand is placed behind the opponent's neck or on their right shoulder, intending to lift them off their feet or press them backward to make them fall, my right hand should be placed on the opponent's center of gravity line. In other words, this can only be implemented when the opponent's center of gravity line is slightly backward, meaning the front leg is solid, and the back leg is light. Otherwise, my tactical intention will be difficult to achieve. Our general principle is: the "striking hand" must always be placed on one side of the center of gravity line; the "guiding hand" must always be on the non-center of gravity line side. Our overall strategy is: through the changes of full-body spiral coiling and the coordination of both hands, make the opponent's "solid leg too solid, and the weak leg even weaker," thereby causing them to lose balance and fall.

In specific offensive and defensive actual combat, facing a moving opponent, constantly changing techniques, and the opponent's skillful repositioning of their center of gravity line, surrounding and destroying the opponent's center of gravity line will not be an easy task. This also demonstrates the richness and mystery of Tai Chi push hands and combat techniques. As the attacking party, on one hand, we can adapt to the enemy's changes, and on the other hand, to achieve our goals, we can force the opponent's center of gravity line to change according to our requirements, which is creating momentum.

For example: if the opponent pushes forward with a right bow step towards me, I can use both hands in a spiral coiling motion to raise their arms, moving my crotch in a downward arc, shifting my center of gravity forward, forcing their heels to rise, and their center of gravity to shift backward. The opponent's center of gravity line changes from back to front, making my frontal attack immediately effective, forcing the opponent to retreat. Another example: if I pull the opponent's right arm towards my right rear, and their right leg forms a bow step resisting my force. At this moment, since the opponent's center of gravity line is slightly backward, they have the condition to resist me. If I simultaneously push their right hip with my left hand, forcing their center of gravity to shift from the right leg to the left leg, and the center of gravity line moves forward, I immediately gain an advantage, and the opponent falls to my right side.

(III) Defense - Shifting, Concealing, Changing, Protecting Our Center of Gravity Line

Stabilizing our center of gravity line is a fundamental element of defense and offense. We can use the transition of the center of gravity, coordination of body methods, folding and transforming through the chest and waist, and adjustments in steps to ultimately ensure that our center of gravity line remains flexible and freely maintains vertical displacement. This keeps the opponent away from our center of gravity line.

Facing the opponent's incoming force, first, we can utilize techniques such as peng (ward-off), lu (rollback), ji (press), and an (push), leading the opponent's force into emptiness. This causes the opponent's force point to always slide along the tangent direction of the circular motion of my limbs, thus neutralizing the opponent's force. The opponent's "striking hand" will never reach my center of gravity line. In this way, without changing my own center of gravity, I can always keep the opponent's force outside my center of gravity line, thereby achieving the purpose of protecting the center of gravity line.

Changing and hiding my center of gravity line involves flexibly and quietly shifting my center of gravity so that the opponent cannot detect or judge the position of my center of gravity line. This hides my center of gravity line, causing the opponent to act blindly and lose advantage, thereby delaying and disrupting the opponent's attack. My limb movements must strictly adhere to Tai Chi's center of gravity theory: if the body turns left, the center of gravity shifts right; if the body turns right, the center of gravity shifts left. (Refer to the paper "Explanation of Tai Chi Lightness, Heaviness, Virtuality, and Reality" for details on Tai Chi center of gravity theory.) At the same time, it is necessary to ensure "the crotch follows a lower arc," making this transition steady and powerful, irresistible.

Destroying the opponent's "striking hand" involves using the coordination of the whole body—through relaxed hips, bent knees, closed crotch, sinking of the body, expansion of the waist arch, spiral arc motion of the arms, and elongation of the entire posture—combined with pushing forward, pulling backward, lifting up, pressing down, and rotating to both sides, ensuring that the opponent's striking hand has no opportunity, preventing the opponent's striking hand from effectively exerting force on my center of gravity line.

Using chest and waist folding to cause the opponent's force point on my center of gravity line to slip:

Once the opponent's striking hand presses onto my center of gravity line, I can use chest and waist folding:

(1) Lean the upper body backward, further shifting the center of gravity forward, while simultaneously lifting the opponent's attacking arm, causing the point of force applied to my center of gravity line to slip upward. This can also lift the opponent's center of gravity, making their feet feel light, allowing me to immediately turn passivity into activity and change tactics to issue the opponent.

(2) Hollow the chest and use both hands to lower the opponent's "striking hand," causing the opponent's "striking hand" to slip downward from my center of gravity line, resulting in them falling forward. This is also an emergency escape method, with significant striking power.

The application of steps provides greater room for guarding the center of gravity line. Once advancing, retreating, looking around, and stabilizing steps are added, my guarding of the center of gravity line has greater flexibility, and the offensive power in defense will greatly increase. Stepping forward and moving the crotch in a lower arc can raise the opponent's arms, even forcing their entire body to lean back and retreat; stepping back can lead the opponent forward, causing their center of gravity line to tilt and fall; looking around to both sides can avoid the opponent's attack on my center of gravity line, create opportunities, and cleverly seize advantages, smoothly transitioning from defense to offense. In Tai Chi push hands, there is a saying, "An expert reveals their skill with just one touch." This refers to the difference in balance and counterbalance forces between the two parties; it refers to the accurate grasp and control of the opponent's center of gravity line. Only through continuous research and contemplation in daily practice, forming habits over time, can we disrupt the opponent's balance upon contact in sparring matches, using minimal force to make the opponent lose stability, eventually hoping to reach the ultimate realm of Tai Chi where "contact leads to falling."