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 16:17:35

The Role of the Human Center of Gravity Line in Tai Chi Attack and Defense from the Perspective of the Golden Ratio

Renowned Tai Chi practitioners are often referred to as "magicians of human balance" for their remarkable dexterity and subtlety in force during push hands and free sparring. This is because Tai Chi emphasizes overcoming strength with weakness, achieving leverage with minimal effort, and particularly focuses on the study of human balance. The center of gravity line is crucial in understanding human balance; thus, when studying Tai Chi, it's essential to understand both the human center of gravity line and its role in Tai Chi attack and defense.

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

An invisible line that runs vertically through the body's center of gravity is called the human center of gravity line. During upright movements, the body is supported by both legs, which shift weight to maintain balance. Maintaining symmetry and balance always revolves around this center of gravity line. Since the two legs support the body's weight differently, the position of the center of gravity line also varies. When the body stands with both legs together, the weight is evenly distributed, and the center of gravity line aligns with the centerline, such as in a preparatory stance.

When the legs bear uneven pressure, forming a solid and empty step, the centerline separates from the center of gravity line. Generally, the leg bearing most of the weight is called the "solid leg," while the other is the "empty leg." According to mechanics, if the center of gravity line is located about one-third closer to the empty foot within the distance between the two feet, it allows for powerful grounding.

This "about one-third" can be more accurately measured using the "Golden Ratio": approximately 0.618 from the solid foot to the empty foot, and 0.382 from the empty foot to the solid foot. If the center of gravity line exceeds this range (i.e., less than 0.618 or greater than 0.382), the empty leg becomes too light, causing the solid leg to tilt.

In the case where one leg supports the entire body weight, the center of gravity line naturally runs vertically up along the supporting leg.

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

In Tai Chi attack and defense, if I am attacking an opponent, I should first identify their weak points. Practice shows that applying force directly onto 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 achieving part or all of our tactical objectives. For example, in cooperative step push hands, if both parties have the right leg forward and left leg back in a bow stance with the center of gravity forward, then both centers of gravity lines should be slightly behind the midline of the body. If I advance to attack, I can use my right hand as the "striking hand" to push against the opponent’s left chest. If the opponent shifts their center of gravity, making the back leg solid and the front leg empty, the center of gravity line moves forward. In this case, my "striking hand" should switch to the left hand, pushing against the opponent’s right chest. Not following these principles will result in ineffective or inefficient attacks. If I want to attack the opponent from the sides, causing them to fall sideways, when the opponent’s center of gravity is on the front leg, I can turn my body to the left, using my left hand as the "guiding hand" to make the front leg overly solid (knee over toes being "excessive"), while the back leg becomes even emptier. My right hand serves as the "striking hand," applying force to one side of the center of gravity line in a spiral manner to upset the opponent’s balance. Conversely, when the opponent’s center of gravity is on the back leg, I should turn my body to the right, using my right hand as the "guiding hand" and my left hand as the "striking hand" to achieve the same effect.

If, during cooperative step push hands, I place my right hand on the opponent’s neck or shoulder, intending to lift them off their feet or press them backward, my right hand must be placed along the opponent’s center of gravity line. In other words, only when the opponent’s center of gravity line is slightly behind (solid front leg, empty back leg) can the Chen-style Tai Chi technique be applied effectively. Our general principle is: the "striking hand" must always be placed on one side of the center of gravity line, while the "guiding hand" must always be placed on the non-center of gravity line side. The overall strategy is to use the changes in full-body spirals and the interplay of both hands to make the opponent's "solid leg overly solid and empty leg even emptier," thus causing them to lose balance and fall.

In practical combat, given the dynamic nature of the opponent and the continuous change in techniques and center of gravity line positions, intercepting and disrupting the opponent’s center of gravity line is not easy. This complexity gives rise to the richness and profundity of Tai Chi push hands and fighting techniques. As the attacker, we can adapt to the opponent’s changes but also force the opponent’s center of gravity line to change according to our needs—this is known as creating momentum.

For example, if the opponent pushes forward with a right bow stance, I can use a spiral motion to raise their arms, shifting my center of gravity forward, forcing their heels to lift and the center of gravity line to move backward, making my frontal attack immediately effective, compelling the opponent to retreat. Another example is when I pull the opponent’s right arm toward my right rear side, and they resist with a right bow stance. Because their center of gravity line is slightly behind, they can counter me. However, if I simultaneously push their right hip with my left hand, forcing the center of gravity to shift from the right leg to the left leg, moving the center of gravity line forward, I immediately gain the advantage, causing the opponent to fall to my right.

(III) Defense - Transferring, Concealing, Changing, and Protecting Our Own Center of Gravity Line

Stabilizing our own center of gravity line is a fundamental element of both defense and offense. We can use the transfer of the center of gravity, coordinated body movements, folding of the chest and waist, and even adjustments in steps to ensure that our center of gravity line remains flexible and maintains vertical displacement. This keeps the opponent away from our center of gravity line.

Facing the opponent’s force, I can use techniques like peng (ward-off), lu (rollback), ji (press), and an (push) to guide the opponent’s force along the tangent direction of the arc formed by my limbs, making their force ineffective. The opponent’s "striking hand" will never reach my center of gravity line, allowing me to keep the enemy's force outside my center of gravity line without changing my own center of gravity.

Changing and hiding my center of gravity line involves flexibly and quietly shifting my center of gravity so 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 become blind and lose control, delaying and disrupting their attack. My limb movements must strictly follow the Tai Chi center of gravity theory: when the body turns left, the center of gravity moves right; when the body turns right, the center of gravity moves left. Simultaneously, I must ensure that my movements follow the "lower crotch arc" principle, making the transition stable and irresistible.

Disrupting the opponent’s "striking hand" involves coordinating my entire body—through relaxed hips, bent knees, closed crotch, sinking of the body, expansion of the waist arch, spiral arc movements of the arms, and elongation of the entire posture—to prevent the opponent’s striking hand from having any opportunity to exert effective force on my center of gravity line.

Through chest and waist folding, I can cause the opponent’s force on my center of gravity line to slip off:

(1) Leaning the upper body backward, further shifting the center of gravity forward, while lifting the opponent’s attacking arm, causing their force point on my center of gravity line to slide upward. This also lifts the opponent’s center of gravity, making their feet feel unstable, instantly turning a passive situation into an active one.

(2) Using the chest to draw down the opponent’s "striking hand," causing their "striking hand" to slide downward from my center of gravity line, resulting in them falling forward.

Using footwork expands the space for guarding the center of gravity line. Once stepping forward, walking the lower crotch arc can lift the opponent’s arms, forcing their body to lean backward and retreat. Stepping backward can lead the opponent forward, causing them to fall due to the forward tilt of their center of gravity line. Looking left and right can avoid attacks on my center of gravity line while creating momentum, leading to clever tactics and transitioning smoothly from defense to offense.

In Tai Chi push hands, there is a saying: "A master reveals their skill with just one movement." This refers to the difference in balance and counterbalance forces between opponents, as well as the precise grasp and control of the opponent’s center of gravity line. Only through constant practice and contemplation, forming habits over time, can we disrupt the opponent’s balance with minimal effort upon contact, ultimately reaching the pinnacle of Tai Chi where "a touch causes a fall."