Extensive literature review on the scientific principles underlying power absorption (Huajin) and generation (Fajin) in internal Chinese and Japanese martial arts. This research integrates both academic sources (peer-reviewed journals on biomechanics, neuroscience, fascia research, and kinesiology) and historical martial arts texts (translated where necessary). The analysis will critically compare traditional martial arts concepts with modern scientific frameworks to demystify their mechanisms. The final output is a structured research document, including a multilingual glossary with phonetic transcriptions in pinyin (Chinese) and hiragana/romaji (Japanese).

I. Research Focus

Traditional East Asian martial arts often describe internal power using esoteric terms, yet many of these concepts align with modern scientific principles. This study focuses on bridging traditional martial arts concepts with scientific understanding. Specifically, it examines Huajin (化勁) – the skill of neutralizing or transforming an opponent’s force – and Fajin (發勁) – the explosive release of power – through the lenses of biomechanics, neuroscience, and fascia research. Classical martial texts speak of energy originating in the legs and waist and flowing out through the limbs; for example, the Tai Chi Classics state that power is “rooted in the feet, issued by the legs, governed by the waist, and expressed in the fingers” (The Taijiquan Classic | The Splintered Staff). Modern science concurs that efficient full-body movement uses a coordinated kinetic chain from the ground up. A biomechanical study of fajin confirms this: the explosive motion “is initiated by a push from the rear foot, which produces a ground reaction force and moves the center of gravity forward,” with joint rotations and muscle activation following a fixed sequence from the legs through the torso to the arms (Archives of Budo – Abstract). Huajin, on the other hand, can be viewed as skilled force absorption and redirection – essentially biomechanics of yielding and leveraging an opponent’s momentum. By examining both historical sources (martial arts treatises, training manuals, masters’ anecdotes) and modern scientific studies (in biomechanics, fascia physiology, and neurobiology), we aim to demystify how internal power is generated and absorbed. This interdisciplinary focus helps translate the metaphorical language of martial arts (like “inner energy” or “listening power”) into anatomical and mechanical terms, building a bridge between ancient wisdom and contemporary science. Ultimately, understanding Huajin and Fajin in scientific terms not only validates traditional training methods with evidence-based insight, but also enriches our scientific knowledge by revealing sophisticated human movement strategies refined over centuries.

II. Martial Arts Scope

Japanese Arts

Kitō-ryū (起倒流) – “Rise and Fall School”: An ancient Jujutsu school, Kitō-ryū specializes in throws and unbalancing techniques. It heavily influenced modern Judo; in fact, kuzushi (崩し) – the principle of breaking an opponent’s balance – was adopted by Judo from Kitō-ryū (KITO RYU Jujitsu — the beginnings of Judo | Judo Info). Kitō-ryū’s teachings emphasize using one’s whole body as an integrated unit to affect the opponent. The term “rise and fall” itself hints at exploiting gravity and body structure: for example, dropping one’s center of mass (fall) to uproot the opponent (rise). In mechanical terms, kuzushi is achieved by shifting the opponent’s center of gravity beyond their base of support, something easily explained by physics and biomechanics. A throw begins by applying force at key points to upset equilibrium, then continues into a smooth projection. The concept of tensegrity (balanced tension and compression in a structure) is illustrative here: the thrower’s body maintains structural integrity (through core stability and stance) even while generating force to disrupt the opponent. By engaging the entire fascial and muscular network (from feet gripping the ground to hands on the opponent), a practitioner creates a connected whole-body leverage system. In effect, Kitō-ryū’s kuzushi exemplifies using one’s “internal frame” to affect another’s balance. Modern biomechanical analysis of Judo throws shows that effective kuzushi involves synchronized leg, hip, and trunk motions that push and pull an opponent in one “connected action” () (). This reflects exactly what Kitō-ryū masters intuitively taught: an unbalancing technique is not about isolated arm strength but about unified body structure. Thus, Kitō-ryū’s seemingly mystical throwing power can be understood as the skillful application of whole-body biomechanics (stance, center-of-mass manipulation, and structural alignment) to exploit an opponent’s instability. The tensegrity-like coordination in kuzushi ensures the thrower remains stable while the opponent is destabilized – a perfect example of traditional principle meeting scientific explanation.

Daitō-ryū Aiki-jūjutsu (大東流柔術) – This school is renowned for its concept of Aiki (合気), often described as a kind of internal power or the harmonization of energy. Practitioners of Daitō-ryū, including legendry masters like Takeda Sōkaku, were said to be able to control and off-balance much larger opponents with minimal apparent effort. In practical terms, internal power in Daitō-ryū comes from precise bone alignment, connected fascia, and expert timing rather than raw muscular force. The term “Aiki” implies blending with the opponent’s force. Instead of meeting strength with strength, the Daitō-ryū practitioner leads the opponent’s aggressive force into a void or unbalanced position, then applies their own force at just the right moment. This aligns with Newtonian mechanics: by matching the direction of an incoming force and slightly redirecting it, one can dissipate an opponent’s power (Huajin) and then add one’s own force to counter-attack (Fajin). Body structure is key – Daitō-ryū training includes drills to develop an “unbendable arm” and stable, rooted stance. In the famous “unbendable arm” demonstration, the practitioner relaxes and aligns their arm bones and shoulder, transmitting force through the skeletal structure and connected tissues instead of through muscular tension. Biomechanically, this is using axial loading of the arm (like a strut) and engaging core stability; it allows even a smaller person to resist a force that would otherwise bend their arm (Internal Strength, Daito Ryu and Aiki – Aikido in Sydney). Advanced Daitō-ryū exponents also talk about a feeling of “softness” that conceals great strength. As Daitō-ryū instructor Roy Goldberg notes, “real Daitō-ryū has a softness that is nearly unmatched… it can be brutal if needed, but that isn’t the goal” (Daito-ryu Isn’t Just Hard Aikido: An Interview with Roy Goldberg – Aikido Journal). Here, “softness” refers to the lack of excess tension – the body is pliant and responsive, able to absorb and redirect force. This softness enables subtle kuzushi (off-balancing) of the opponent; indeed, certain Daitō-ryū lineages like Kodokai and Sagawa-ha place heavy emphasis on extremely subtle, almost imperceptible, unbalancing methods (Daito-ryu Isn’t Just Hard Aikido: An Interview with Roy Goldberg – Aikido Journal). From a scientific perspective, a relaxed body state allows faster neuromuscular response and better force transmission via connective tissues. When an expert applies Aiki, they connect to the opponent’s body through touch, sense the direction of their force (a high-level form of proprioception), and adjust their own body (through micro-alignments of joints and engagement of fascia) to lead that force harmlessly away. Force is transmitted along the practitioner’s aligned frame and into the ground. Then, by coordinating a swift return of force (often through a unified whole-body pulse or drop of weight), the practitioner can send the opponent off-balance. The effectiveness of Daitō-ryū techniques can thus be explained by refined coordination and sensitivity: trained neural pathways that allow detection of slight pressure changes (analogous to the “listening skill” in Tai Chi) and the habit of maintaining optimal posture for force transfer. In summary, Daitō-ryū’s internal power is a combination of leveraging biomechanics (structure, leverage, timing) and heightened neuromuscular control (sensing and responding to force)– the “mystique” of Aiki reveals itself as advanced physics and physiology in action.

Yagyū Shinkage-ryū (柳生新陰流) – A classical Japanese sword art, Shinkage-ryū is less explicitly about “internal energy” than the empty-hand arts, but it embodies internal principles in strategy and body usage. Yagyū Shinkage-ryū teachings highlight concepts like “mutō dori” (techniques for when one is unarmed against a sword) and an emphasis on mental composure and posture. Writings by Yagyū Munenori stress the importance of an alert but calm mind and a body that can move freely without telegraphing intent. One famous concept from this school is “mukei no kurai” (無形之位), which means “formless stance” or “position of no form”. In practical terms, this means the swordsman holds no fixed posture – there are no tense muscles or rigid positions for the opponent to read. One waits in a neutral, relaxed readiness, able to respond to whatever comes (Kenjutsu (剣術) (Swordplay) – Japanese Wiki Corpus). This is analogous to the internal idea of emptiness: presenting no force for the opponent to resist or exploit. Some interpret Shinkage-ryū’s highest level as achieving “empty force”, not in the supernatural sense but as a strategy where the opponent is defeated by their own movements and openings. Munenori advised “目に見えぬ本質を悟ること” (me ni mienu honshitsu wo satoru koto), meaning “to perceive the essence that cannot be seen with the eye” (構えありて構えなし <宮本武蔵「五輪書」>). In context, this refers to sensing an opponent’s intent and rhythm – an intuitive understanding of the unseen factors in a fight. Physically, Shinkage-ryū practitioners trained their bodies to be like a spring: relaxed but ready. This is a form of whole-body tensegrity usage – even holding a sword, the power comes from a balanced, taut-but-yielding body structure, not from muscling the weapon. For example, in delivering a cut or responding with counter-technique, power is generated by a coordinated movement of the body (legs, hips, torso, arms as one unit) rather than an isolated arm swing. The strategic positioning of Shinkage-ryū – stepping off-line, entering at precise angles – also mirrors principles of momentum redirection found in empty-hand arts. By positioning oneself in the right place, a Yagyū swordsman could use very little force to achieve a cut or disarm, analogous to how a judoka uses position to throw with minimal effort. In modern biomechanical terms, Yagyū Shinkage-ryū’s teachings imply an expert command of balance, center of mass control, and efficient force vectors. Even though wielding a sword is involved, the core body mechanics (balance, relaxation, timing) are the same “internal” skills: a stable, responsive structure (like a well-engineered tensegrity model) and a mind that can react without hesitation. Thus, Shinkage-ryū demonstrates that internal principles are not limited to empty-hand styles – they permeate weapon arts as well in the form of subtle body control and psychological acuity. The “invisible force” here is strategy married to structure: the ability to strike or defend in a way that the opponent experiences as if you had an almost preternatural skill, when in fact you are applying impeccable physics and perception.

Additional Japanese Concepts: Traditional Japanese budō training frequently references personal development and internal principles that complement physical techniques:

• “自分を作る” (Jibun wo Tsukuru) – “Building oneself.” Jigoro Kano, the founder of Judo, emphasized that judo is as much about self-improvement as combat. He famously said the ultimate aim is “to train and cultivate body and mind…and to attain perfection of oneself and bring benefits to the world.” (Jigoro Kano (1860-1938) – Judoencyclopedia by Thomas Plavecz History – Pioneers – Techniques). This reflects the idea that rigorous training (tanren) forges one’s character and body together. Physically, this “forging” corresponds to the adaptive changes in the body – increased strength, flexibility, and coordination – and mentally, it’s increased focus and resilience. Judo’s principle of “seiryoku zen’yō” (maximum efficiency, minimum effort) ties directly into internal principles: use the least force for the greatest effect, which is achieved by perfect timing, balance, and body unity rather than brute strength.
• “目に見えぬ本質を悟ること” (Me ni Mienu Honshitsu wo Satoru Koto) – “Understanding the invisible essence.” This phrase, echoed by masters like Musashi and in other budō teachings, points to perceiving subtleties beyond outward appearances. In martial arts, this often means sensing your opponent’s intent or the underlying physics of an encounter. For instance, an adept must feel an opponent’s balance and intent through a grip or point of contact – something that western science would frame as tactile sensibility and proprioceptive feedback. It also implies seeing the “invisible” in oneself: understanding how internal factors like one’s own breathing, tension level, and mindset can decide an encounter even before physical contact is made.
• “鍛錬” (Tanren) – “Forging (body and spirit).” Japanese arts use this term to describe repetitive training that hardens the body and refines technique – much like a swordsmith repeatedly folds and forges steel. Examples include suburi (repeated sword swings), tegumi (grappling drills), and kata practice. Over time, tanren training causes physiological adaptations: muscles and connective tissues strengthen (even bones become denser under repeated stress), and movements become second nature (neural pathways are myelinated for efficiency). This is essentially specific conditioning. In internal terms, tanren is how one builds the “body frame” (Judo might call it taiiku, physical education) necessary to manifest techniques that look effortless. A modern interpretation is that such training improves intermuscular coordination and fascial elasticity – the body learns to function as one unit. Spiritually, the forge also purifies the spirit – teaching patience, humility, and focus, which neuropsychologically can be seen as improved concentration and stress management (as we will discuss under neuroscience).

In all these Japanese concepts, we see a common thread of integrating mind, body, and technique – which is exactly the domain of internal strength. They understood that how one uses the body (posture, relaxation, intent) is more important than raw muscle. Science now can explain that using the body as an integrated system (efficient kinetic chains, optimized neural recruitment, connective tissue conditioning) is what makes “internal” feats possible. The Japanese masters were, in essence, early empiricists of human biomechanics and psychology, encoding their findings in aphorisms and training methods that have stood the test of time.

Chinese Arts

Xingyiquan (形意拳) – Known as “Form-Intention Boxing,” Xingyiquan is the epitome of linear, direct power generation among Chinese internal arts. Xingyi practitioners generate explosive forward power through coordinated stepping, twisting of the hips, and striking in a single waveform of force. This explosive power release is Xingyiquan’s version of fajin. Modern biomechanical analysis reveals that such a strike is not a mere arm punch – it originates from the push of the rear leg, travels through the torque of the hips and spine, and expresses out the striking limb. In other words, Xingyi fighters use the ground and their whole body mass to generate strikes. In the fajin study on martial artists, even though it wasn’t specific to Xingyiquan, the findings apply: every subject utilized a kinetic chain from legs to waist to arm, with peak joint rotations occurring in sequence (Archives of Budo – Abstract). This is precisely what Xingyi’s classic teaching “move like a high-speed locomotive” implies – the idea that the entire body moves as one unit behind each strike. Xingyiquan also emphasizes a posture called Santishi (三體勢) – a triangular stance used in training. Zhan Zhuang (standing practice) in Santishi develops rooted legs, an elastic torso, and linked arms. Fascia research provides insight here: fascia forms a continuous network linking muscles across joints, so training a static structure like Santishi with intent (yi) and slight whole-body engagement may strengthen the myofascial connections. Indeed, fascia allows the body to “move as a single unit” – it “forms a continuous network that covers and connects organs, muscles, even nerves,”enabling integrated movement (Fitness – Ken Gullette’s Internal Martial Arts). This suggests that part of Xingyiquan’s internal power comes from cultivating strong myofascial recoil. Xingyi strikes often have a penetrating quality described as “drilling” or “bursting.” When a practitioner launches a strike, there is a coordinated foot drive, a corkscrewing of the hips (many Xingyi punches have a spiral component), and a synchronized extension of the arm. The muscles, tendons, and fascia are preloaded by the twist and step, then released like a compressed spring uncoiling. Elastic energy stored in the Achilles tendon, iliotibial tract, and thoracolumbar fascia during the wind-up can contribute to the power upon release. Chinese descriptions sometimes speak of “activating Jin (internal strength) in the tendons” – we can interpret this as engaging the fascial elastic components. From a neurological perspective, Xingyi’s training of intention (意) with movement likely improves motor unit recruitment: the practitioner learns to fire many muscle fibers in a brief, sudden pulse (an aspect of motor control also seen in weightlifting’s power training). Moreover, the Xingyi classic three-tier theory (Ming Jin, An Jin, Hua Jin) identifies Hua Jin (the transforming, elastic force) as the highest level (A Treatise on Xingyi Quan’s Three Jin 形意拳明暗剛柔三勁論 – By Master C S Tang – Singing Dragon and Handspring Blog) (A Treatise on Xingyi Quan’s Three Jin 形意拳明暗剛柔三勁論 – By Master C S Tang – Singing Dragon and Handspring Blog). Interestingly, it calls Hua Jin “elastic strength, twisting strength, the mystique of change, the wonder of dissolving”(A Treatise on Xingyi Quan’s Three Jin 形意拳明暗剛柔三勁論 – By Master C S Tang – Singing Dragon and Handspring Blog). This classical description matches well with our modern understanding of elastic recoil and redirection of force. Hua Jin in Xingyi means the fighter can neutralize an incoming force and return it with interest – a skill that would require excellent timing and tissue elasticity. In summary, Xingyiquan’s linear and explosive movements are grounded in solid biomechanics (whole-body coordination, ground reaction force) and augmented by internal training that conditions the fascia and nervous system to deliver bursts of power. This makes its Fajin extremely fast and heavy, yet also “alive” – able to adapt or change angle mid-movement, much like a shock absorber that can also release a bounce.

Bāguà Zhǎng (八卦掌) – Literally “Eight Trigrams Palm,” Baguazhang is famous for its circular walking and twisting body movements. The practitioner constantly steps in circles and changes direction, generating power through angular momentum and centrifugal force. Baguazhang’s power generation is often a spiraling force – imagine wringing a towel and then snapping it straight. In combat, Bagua practitioners will sidestep and rotate around an opponent, seeking to use redirection and flank attacks. Internally, Baguazhang training strengthens what we might call the “spiral lines” of the body: the diagonal chains of muscle and fascia that run from shoulder to opposite hip (and vice versa). When a Bagua fighter coils their body (for instance, twisting the torso while stepping around), they are loading these myofascial slings. Uncoiling suddenly can release significant power in a strike or throw. This is analogous to storing energy in a spring via torsion. Anatomically, one such myofascial connection is through the thoracolumbar fascia – connecting latissimus dorsi on one side to the gluteus maximus on the opposite side. Studies have shown that force can indeed transmit between these cross connections (for example, contracting the lat on one side can transmit force to the opposite hip) ( Intermuscular force transmission along myofascial chains: a systematic review – PMC ). Baguazhang’s body method capitalizes on such connections; a classic Bagua palm strike might start with a push from the left foot, a torque of the waist to the right, and a strike with the right palm – effectively channeling force from left foot to right hand through that diagonal connection. Another hallmark of Baguazhang is constant motion and change – “like a dragon flipping and turning,” as some texts describe. This trains agility and reflexes, but also an advanced sense of balance (knowing where your center is even in dynamic rotation). The circular footwork of Bagua is essentially an exercise in controlling centrifugal force – too slow and you lose power, too fast and you lose balance. A skilled practitioner can make their limbs whip outward with great force but still recall them or change direction instantaneously. This resembles a figure skater’s controlled spins, but applied to fighting. From a physics standpoint, moving in a circle and then suddenly straightening out (for a strike) converts rotational momentum into linear momentum aimed at the opponent. Internally, Bagua forms often incorporate “open-close” motions of the chest and “wrapping” motions of the arms. These serve to coordinate the upper body with the lower and to employ “tensegrity” – when the arms wrap or coil around the body, the whole torso unit tightens slightly (like winding a spring), and when they release to strike, the stored energy plus the structural rebound of the torso contributes to force. Moreover, Baguazhang is known for yielding and redirecting incoming attacks. The phrase “lead the opponent in a circle” embodies the idea of taking a linear attack and guiding it into a circular path, dissipating its threat. Biomechanically, this is done by rotating around the point of contact and using small pivots – in effect, using the opponent’s force to continue the motion in a curve. The ability to do this requires superb proprioception and balance, as well as relaxed strength to keep one’s structure intact during movement. In internal terms, Bagua practitioners develop a quality called “tongbei” – unity of the back, meaning the whole back (and by extension the whole body) moves as one coordinated organism. In modern terms, this could be seen as ensuring all core muscles and fascia engage harmoniously during movement, distributing forces evenly (tensegrity again). Fascia research supports the benefit of such whole-body movements: by engaging multiple fascial chains through twisting and turning, Bagua may enhance the elasticity and hydration of connective tissues across the body. In doing so, the body becomes more pliable and resilient – able to absorb forces from awkward angles without injury and return force unpredictably. Thus, the “circular” power of Baguazhang, often spoken of in metaphors (like “moving like a whirlwind” or “coiling like a snake”), can be understood through science as momentum redirection, coupled with elastic recoil and coordinated rotational biomechanics.

Yì Quán / Dà Chéng Quán (意拳 / 大成拳) – Yiquan (also called Dachengquan, “Great Achievement Boxing”) is an art that distills the principles of the internal styles into a minimalist training regimen focused on standing meditation and spontaneous movement. Founded by Wang Xiangzhai, Yiquan eschews set forms; its core practice is Zhan Zhuang (站桩), or standing post, often in a basic stance with arms held as if hugging a tree. At first glance, standing still might seem unrelated to martial power, but internally a great deal is happening. Zhan Zhuang develops aligned posture, relaxed concentration, and proprioceptive awareness. When standing, the practitioner strives to release excess tension (Song) and align each joint optimally (head over shoulders over hips over knees over feet). Small internal adjustments are made to find the state of “relaxed strength” – not limp, but not stiff. This trains the neuromuscular system to hold structure using minimal effort, relying on bones and ligaments for support (like a well-stacked column) and just enough muscle tone to maintain balance. Over time, the connective tissue (fascia and tendons) in the body is thought to remodel and strengthen in response to this sustained standing. In scientific terms, holding mild postural stress for long durations can stimulate collagen alignment in fascia and increase lower-level muscle activation endurance. Yiquan practitioners also use intent (Yi) visualization during standing – for example, imagining pushing or pulling against resistance while not actually moving. This is essentially isometric exercise combined with motor imagery, which has been shown to improve strength and coordination by enhancing neural recruitment patterns. After extensive standing practice, Yiquan training includes shili (試力 – “testing force”) and fali (發力 – “issuing force”) exercises, which are very simplified, free-form movements where one maintains the integrated feeling from standing while moving slowly, then eventually issues short bursts of power. Because there are no codified forms, the practitioner learns to generate power from any position or movement, guided by principles rather than choreography. One of Wang Xiangzhai’s famous quotes is: “All sorts of strengths originate in the void and nothingness, which can only be felt gradually by the tiny edges and corners of the body.”(Grandmaster Wang Xiang-Zhai (1885-1963) – 內功 Neigong.net). This poetic statement reflects the idea that when one’s body is free of unnecessary tension (“void and nothingness”), subtle sensations (in muscles, joints, fascia – the “tiny edges and corners”) become perceptible, and from those subtle cues one can build great strength. In modern parlance, this describes an advanced state of body awareness and fine motor control – essentially body and mind integration at a high level. Indeed, neuroscience would suggest that such training increases the brain’s map of the body (homuncular representation), meaning the practitioner can activate or relax parts of the body at will with great precision. Yiquan’s spontaneous movement exercises (sometimes called shi sheng, testing voice, for emitting sound with strikes, or simply free shadowboxing) allow the practitioner to apply their refined body state dynamically. Without set techniques, they must rely on the fundamental internal skills: rooting, centering, issuing from the dantian (lower abdomen), and using intent to drive movement. This trains adaptability – the nervous system learns to quickly organize the body’s structure for whatever motion is needed, rather than following a pre-set pattern. In Western terms, it’s like teaching the body to solve movement problems in real-time by drawing on ingrained principles (balance, unity, relaxation). The result is a fighter who can manifest sharp power from seemingly awkward positions or create force in any direction without obvious wind-up. Modern measurements might observe that an experienced Yiquan practitioner can generate significant ground reaction forces and impulse even without a preliminary step or swing – indicating an ability to rapidly coordinate muscle groups in a short time frame. Additionally, standing meditation has a known effect on the autonomic nervous system – it tends to reduce sympathetic arousal and increase parasympathetic activity (a calming effect), similar to other meditation. This likely contributes to Yiquan practitioners often being very calm and centered even under pressure (low baseline heart rate, high heart rate variability, etc.), which is a psychological edge in combat. Summing up, Yiquan exemplifies internal training stripped to its essence: through static and slow movements it engrains proper alignment and whole-body connection (structural and neurological), and through intent-driven explosive practice it develops the ability to issue power spontaneously. Scientific analogies are found in motor control theory (improving the efficiency of neural circuits controlling movement) and connective tissue physiology (strengthening passive recoil elements) – both of which clearly play a role in the observable power that advanced Yiquan/Dachengquan practitioners can generate. Yiquan’s success in forging powerful fighters (as history records) provides living evidence that internal principles alone, applied with focused training, are sufficient to achieve high-level martial skill. This makes it a perfect case study for our research focus.

Tài Jí Quán (太極拳) – Commonly known as Tai Chi, this art is often characterized as “soft, slow, and internal.” Its reputation sometimes leans more towards health and meditation, but traditional Tai Chi is a highly refined martial art that embodies the pinnacle of internal power usage. The fundamental Tai Chi concept is “using softness to overcome hardness.” In practice, this means using yielding, redirection, and well-timed counter-force rather than meeting force with force. Key Tai Chi principles include: Peng (掤) – a subtle expanding resilience (often likened to an inflatable ball’s quality), Lu (履) – withdrawing or diverting, Ji (擠) – pressing forward, An (按) – pushing downward. These, along with other energies, are all manifestations of refined force control. When confronted with an incoming force (e.g., a push or strike), a Tai Chi adept will first receive and neutralize it – this is Huajin in action. They do so by “listening” to the force, an ability called Tīng Jìn (聽勁) ( Effect of tai chi exercise on proprioception of ankle and knee joints in old people – PMC ), literally “listening energy.” Physically, this refers to sensitivity in the nerves and fascia to feel the direction, magnitude, and intention behind the force. The practitioner maintains light contact and a relaxed arm, which allows them to sense even subtle changes (much as a sensitive car suspension system responds to bumps). Once they have harmonized with the opponent’s motion, they can lead it into emptiness – “引进落空” in Tai Chi parlance, meaning “guide [the force] in and make it fall into nothing.” For instance, if pushed on the chest, instead of resisting, the Tai Chi practitioner might rotate at the waist and shift weight back, deflecting the push to the side so the opponent stumbles forward with nothing to press against. This is pure physics: redirect the vector of force away from one’s center. Because the Tai Chi practitioner stays sōng (鬆) – relaxed and loose yet structured – their body can absorb the incoming momentum by elastically deforming (joints turning, spine slightly compressing, etc.) and then spring back when needed. Song is crucial; it does notmean floppy – it means no excess tension, like a steel spring: firm but flexible. Modern biomechanics would note that a relaxed muscle can stretch and store elastic energy more effectively, and a relaxed state also means quicker reaction (since muscles aren’t pre-contracted incorrectly). The concept of “黏黏連隨” (Zhān, Nián, Lián, Suí) (A Treatise on Xingyi Quan’s Three Jin 形意拳明暗剛柔三勁論 – By Master C S Tang – Singing Dragon and Handspring Blog) – sticking, adhering, connecting, following – summarizes how a Tai Chi fighter handles an opponent: they stick to the opponent’s limb gently, follow its motion closely, remain connected as one unit, and thereby control the interaction. This is essentially maintaining continuous contact to monitor and influence the opponent’s center of mass. In push-hands practice (Tui Shou), two players attempt to unbalance each other using these principles; strength alone is neutralized by technique. Tai Chi classics say “四两拨千斤” – “four ounces deflect a thousand pounds,” implying a small redirection can overthrow a great force if applied at the right moment and angle. Scientifically, this reflects leveraging biomechanics and timing: a slight force applied orthogonally to the opponent’s force can change its trajectory, especially if applied when the opponent is in motion (hence less stable). After neutralization (huajin), Tai Chi seamlessly transitions to fajin – the release of power. The stored elastic energy and the opponent’s compromised position provide the perfect setup for a powerful counter. In a split second, the practitioner will fa jin: perhaps a short sharp push or a strike generated by a sudden coordination of the whole body. Chen-style Tai Chi, for example, has explicit fast movements where the body unwinds explosively. Instrumented tests of Tai Chi masters have shown that their seemingly gentle pushes can generate significant force on an opponent – often by accelerating the opponent when they’re already off-balance rather than by raw impact. An interesting scientific finding is that long-term Tai Chi practice improves balance and proprioception. Studies comparing elderly Tai Chi practitioners to non-practitioners found significantly better joint position sense and kinesthetic awareness in the Tai Chi group ( Effect of tai chi exercise on proprioception of ankle and knee joints in old people – PMC). This corroborates the internal skill of “listening energy” as an actual enhancement of the body’s sensory capabilities through training. Fascia and tensegrity also play a role: Tai Chi’s slow movements through wide ranges of motion gently exercise the connective tissues, increasing their suppleness. The concept of “peng jin” can be likened to a well-distributed tensional integrity in the body – any incoming force is spread throughout the structure (like pressing on a water-filled balloon, the force is not localized). A network of engaged fascia can distribute forces, preventing a hard impact on any single point; this may be why Tai Chi practitioners can absorb pushes that would topple others. Tai Chi’s emphasis on an upright posture and sunk hips (as if sitting) ensures that the skeletal alignment is optimal (the spine like a suspended string of pearls). This allows gravity and ground reaction forces to travel clearly through the body. In effect, Tai Chi is constantly training the body to behave as an integrated unit controlled by a calm, present mind. Brain studies on Tai Chi have even indicated changes in brain structure and function – for instance, improved connectivity in regions related to proprioception and attention (Tai Chi Chuan Alters Brain Functional Network Plasticity … – Frontiers). This suggests that the “internal” aspects (mindfulness, awareness) in Tai Chi produce measurable neuroplastic changes. In martial application, a Tai Chi practitioner might appear to casually float aside and then, with a short issuance, send an opponent stumbling. There’s no obvious musculature effort – because the work was done internally: by sensitivity, body unity, timing, and clever use of physics. To summarize Tai Chi’s internal mechanics: yield until you can overcome. Yield by absorbing and sensing (a skill rooted in enhanced proprioception and flexible fascia), then overcome by issuing power from the ground up (using coordinated muscle contractions and stored elastic energy), all while remaining balanced and centered. Tai Chi Chuan thus represents a highly sophisticated synergy of biomechanics and neuropsychology – truly a pinnacle of internal martial science dressed in art’s clothing.

Comparative Analysis of Internal Principles

Despite differences in technique and culture, the internal principles observed in the Japanese and Chinese arts above have remarkable commonalities. Across these disciplines, masters learned to maximize biomechanical efficiency and neuromuscular effectiveness, often in parallel ways. Here we identify some of the common biomechanical and internal principles and how they manifest similarly in multiple arts:

• Whole-Body Coordination (Kinetic Chain Unity): All internal arts train the body to move as a connected whole rather than as isolated parts. In Chinese terms, power comes “from the heels, travels through the legs, is directed by the waist, and manifests at the limbs” (The Taijiquan Classic | The Splintered Staff). In Japanese Jujutsu and Aikido, the concept of using one’s “koshi” (hips/center) to throw or pin rather than just the arms reflects the same idea. Modern science confirms that punches, pushes, and throws are most effective when they employ a full kinetic chain – e.g., a study of fajin across different martial artists found that “all of the joint operations and muscle activation timings occurred in a fixed sequence” for optimal force transfer (Archives of Budo – Abstract). Thus, internal martial traditions intuitively grasped the value of sequential joint activation and synchronized muscle firing long before biomechanics gave us terms like “sequential summation of forces.” Whether it’s a Xingyi straight punch or a Judo hip throw, the power starts at the ground and flows through the body in order – a universal principle.
• Structural Alignment and Posture: Internal power requires a strong yet supple structure. Martial artists emphasize upright, relaxed posture (e.g., head lifted, spine elongated, shoulders down). Such alignment allows forces to travel through the skeleton. Daitō-ryū’s unbendable arm and Tai Chi’s peng jin both rely on aligning bones to efficiently transmit force. In essence, the body is used like a well-aligned stack of blocks (or a column) that won’t collapse under pressure. Bone alignment minimizes leverage disadvantages – for example, keeping the spine vertical and joints “open” can prevent an incoming force from creating a bending moment that unbalances you. We see this in Judo’s throws (tori stays straight and drops weight through aligned legs) and in Bagua’s footwork (a straight, stable torso while legs rotate around). This principle is reflected in the tensegrity model of the body: if the joints (compression elements) are aligned and the connective tissues (tension elements) are appropriately tensioned, the structure can handle external stresses robustly. Internal artists often speak of “stacking the bones” or “threading the nine pearls” (an image from Tai Chi of aligning nine main joints); science would speak of proper skeletal alignment and posture – truly two phrases for the same concept.
• Relaxation (Song) and Softness: Paradoxically, the ability to generate great force stems from the ability to be relaxed at will. All the arts highlight relaxation – not limpness, but a state of no excess tension. In practical terms, being relaxed means the muscles are not fighting each other (antagonist vs agonist), leading to more efficient force generation. The fajin study noted that those unfamiliar with the skill often had “antagonistic muscle responses and waste of energy” when trying to push, whereas trained individuals eliminated that inefficiency (). Additionally, relaxation improves sensitivity – you can’t feel the opponent’s force if your muscles are rigid. This is why Tai Chi push-hands and Aiki techniques demand a calm, relaxed contact. Aikido founder Ueshiba’s ability to redirect a strong attack gently, or a Wing Chun expert’s soft deflection, are quintessential examples. From a physiology standpoint, maintaining lower muscle tension until the decisive moment means the stretch reflexes and mechanoreceptors in your muscles and fascia provide clearer feedback (since they aren’t pre-engaged). It also means when you do contract to issue power, you can contract faster (fewer opposing muscle fibers to overcome). We see congruence in Japanese arts: Judo’s maximum efficiency principle implies no wasted muscular effort; one stays loose and only tightens at the throw’s completion. Similarly, Kenjutsu’s “fluidity” – the ability to move the sword smoothly – comes from not choking the grip or tensing the shoulders. Across the board, relaxed preparedness is key. This “softness” puzzled outsiders who expected martial strength to feel hard – but internally trained bodies feel supple until the moment of impact. That is exactly the trait of a well-conditioned neuromuscular system – the ability to swiftly alternate between relaxation and contraction.
• Ground Connection and Rooting: Internal arts repeatedly emphasize rooting oneself to the ground (as if having deep roots or being heavy) while making the opponent lose their root. This has a clear scientific basis: ground reaction force is what ultimately allows you to apply force to another (per Newton’s third law). By lowering the center of gravity and maintaining balance, an internal artist ensures they can harness maximum friction and push from the ground. In physics, this is maximizing the static frictional force so you don’t slip, and aligning your force vector through your center so you don’t topple. Techniques like kuzushi in Judo or off-balancing in Aiki explicitly aim to disturb the opponent’s center and break their connection to the ground. The opponent becomes essentially a pendulum ready to fall, having no force to brace with. Meanwhile, the rooted practitioner feels “heavy” to the opponent. Stories of Wang Xiangzhai or Yang Luchan being impossible to push over, or Ueshiba standing seemingly unmovable, illustrate this point. They had trained to sink their weight (without tensing) such that any force applied to them went to their feet and into the ground. Modern force plate measurements would likely show an expert can rapidly adjust their stance to channel incoming force straight down (increasing vertical ground reaction force momentarily), thus neutralizing it. We also see this in stance training (Horse stance, Santi stance, etc.) across arts – building leg strength and connective tissue so that one can root on demand. In summary, whoever controls the ground connection in a fight controls the exchange of forces. Traditional wording: “root like a tree.”Scientific wording: low center of mass, good base of support, optimal angle of force into the ground.
• Storing and Releasing Elastic Energy: Many internal techniques can be viewed as capturing an opponent’s force or one’s own kinetic energy, then redirecting or releasing it powerfully – essentially using the body’s elastic components. When a Taijiquan adept receives a push and then fa jins, they have in effect absorbed energy and then added their own to bounce the opponent out. Likewise, a quick recoil in Bajiquan or a springy rotation in Baguazhang takes advantage of stretch-shortening cycles in muscle and tendon. Modern sports science recognizes that a muscle-tendon unit can output more force if an active stretch (eccentric contraction) precedes the contraction – the basis of plyometric training. Internal arts often create these conditions within a single move: e.g., a Chen Taiji practitioner might do a slight counter-move (like a coil back) that stretches their fascia and muscles, immediately followed by an explosive strike. The timing must be precise to capitalize on the stored elastic energy and the neurological potentiation. Japanese arts also have analogues: the springiness of a well-executed throw or the snap of a Karate punch (traditional Okinawan karate has many slow then fast motions, which is a related idea). Even the concept of “feint high, strike low” in swordsmanship could be seen as storing potential (drawing opponent’s attention or causing a reaction, which is a bit different – more psychological storage). The common idea is efficiency – use what’s given. In Jujutsu, if someone pulls you, you don’t resist, you yield (store) and then push when they are off balance (return). This cycle of yield-and-strike or “store-recover” is something our fascia does well if trained (as shown in studies of fascia’s role in movements like jumping). Hence, internal arts masters frequently exhibit a rebounding quality – their limbs or body recoil slightly upon contact and then issue force, much like a rubber ball that first compresses then bounces. Through training, they have optimized this effect (while untrained people either go completely limp – no bounce – or too stiff – no absorption).
• Sensitivity and Timing (Proprioception & Neural acuity): A perhaps less “visible” but universally crucial internal skill is heightened sensitivity to both one’s own body and the opponent’s body. We’ve mentioned ting jin(listening energy) – this is essentially an expert level of proprioception and touch sensitivity. Scientists have found that practices like Tai Chi can improve proprioception in joints by increasing the frequency or lowering the threshold at which mechanoreceptors fire ( Effect of tai chi exercise on proprioception of ankle and knee joints in old people – PMC ). In plain terms, experts can detect smaller changes in pressure or position. Japanese arts develop this in exercises like Kakari-geiko or continuous sparring, where one learns to feel the opponent’s balance and openings. Timing goes hand in hand with sensitivity: recognizing the exact moment an opponent is weak (e.g., at the end of their inhale, or mid-step) and exploiting it. This is neurological reflex training – through countless repetitions and matches, the martial artist’s brain has encoded patterns that trigger the appropriate response faster than conscious thought. Many masters speak of “no-mind” (無心 mushin), meaning they react automatically. In a reflex sense, this is accurate: the spinal or subcortical reflex loops respond to stimuli trained by years of practice, faster than if one had to think. A modern example is how experienced drivers react to hazards faster than novices because their brain has seen the pattern. Likewise, an internal artist feels a shift in the opponent’s center a split-second before it manifests fully and capitalizes on it. In effect, through training, action and reaction merge – when the opponent moves, the practitioner’s body instantaneously issues the complementary counter. Neuroscientifically, this could involve changes like faster cerebellar processing or more efficient sensorimotor cortex connections; interestingly, brain scans of long-term martial artists show differences in areas related to sensorimotor integration and even structural changes in white matter connectivity (Can Taichi Reshape the Brain? A Brain Morphometry Study – PLOS). The result in combat: it appears the master has “anticipation” or “reads minds,” but it’s really educated timing and superior perception. Both Chinese and Japanese anecdotes abound of masters who seemed to always be a step ahead – a testament to this trained sensitivity and timing.
• Minimum Effort, Maximum Effect: All internal arts cherish this concept. It’s essentially the holy grail of biomechanics: optimal transfer of momentum with minimal energy leak or counter-force. Jigoro Kano phrased it as “maximum efficiency”; Chinese call it “using four ounces to move a thousand pounds.” The technical way to achieve this is by applying force at the right angle, at the right time, and at the right point. In lever mechanics, a small force at the right lever arm can move a big weight – martial arts find those lever arms on the human body (for instance, a slight upward lift at someone’s elbow can break their balance strongly because it acts on their whole body lever). Internally, achieving this also requires that the practitioner not waste their own energy in clumsy movements or fighting themselves (tense muscles, poor footing, etc.). We saw evidence in the fajin study conclusion that despite different styles, martial artists “converge towards the achievement of the same objectives” in efficient fajin (Archives of Budo – Abstract) – implying there is an optimal method that human bodies gravitate to for power generation. The same likely holds for power absorption. When we examine different arts side by side, we see they indeed converged on similar ideas. For example, spiral movement is prevalent in Hapkido, Aikido, Bagua, and even Western wrestling – because a spiral is a very efficient way to redirect linear force. Body rotation to add power is used in boxing, karate, Xingyi, and swordsmanship alike – because angular momentum adds power without additional effort (using body weight). Drop your weight appears in Taiji (to uproot or to issue), in Judo (drops and sacrifices), in striking (dropping into hits) – all using gravity to assist technique. None of these masters knew of biomechanics formulas, but through trial and error they honed in on these efficiency boosters. In effect, the internal methodologies all seek to remove the superfluous and emphasize the advantageous. From a training perspective, forms, kata, standing, etc., are all ways to engrain optimal movement patterns into the body. Over years, the practitioner’s default movement becomes the most efficient one. This is analogous to how a seasoned craftsman uses the exact amount of force and no more – it looks effortless. An internal martial artist using Huajin or Fajin appears almost effortless because they are channeling force in the ideal way, with perfect structure and timing, thereby needing very little muscular exertion for a big outcome.
• Psychological and Physiological Integration: While perhaps outside pure “biomechanics,” it’s worth noting that all internal arts equally stress the unity of mind and body – a factor modern science recognizes in peak performance. Breathing techniques (such as deep abdominal breathing in Tai Chi or Aikido’s breath power Ki exercises) stimulate the vagus nerve and keep the practitioner calm under duress (Tai Chi Effects on Heart Rate Variability: A Systematic Review and …). A calm mind makes for better decisions and faster reactions. Visualization (intention) training in Yiquan or Karate’s mokuso (meditation) likely enhances focus and reduces the cognitive load in a fight. The concept of “emptiness” or “no-mind” is effectively a trained state of flow, which sports science has shown to correlate with improved performance and reaction time. Hence, internal principles include what we might call today psychophysiological conditioning – lowering heart rate, controlling adrenaline, staying mentally centered. This too is common across arts: the meditative standing of Yiquan, Zen influence in Japanese Budo, Qigong in Chinese systems, etc. The outcome is that an internal martial artist not only moves efficiently but also processes the situation efficiently, without panic or hesitation. Modern studies on martial artists have found, for example, differences in stress hormone response and brain wave patterns compared to untrained individuals when under simulated combat stress, indicating that traditional training indeed alters one’s internal milieu for performance.

In conclusion, the comparative analysis reveals that internal martial arts – whether Japanese or Chinese – share a core set of biomechanical and neurological principles. They each teach how to use the human body in the most effective way possible: as a coordinated, structure-supported, sensor-equipped, and mind-guided system. Historical masters like Takeda Sōkaku or Yang Chengfu may have used different terminology and training methods, but ultimately they achieved similar feats (throwing or striking with astonishing power and ease) by adhering to the same underlying truths of human movement. With modern science, we can appreciate that what appears mystical is in fact deeply practical – a sophisticated knowledge of body mechanics and human physiology encoded in tradition. By studying multiple arts together, we see this convergence even more clearly. It not only validates the arts through cross-comparison (if both a Chinese boxer and a Japanese jujutsuka independently discovered soft-neutralizing and kinetic chaining, it strongly suggests those are fundamental human principles), but it also provides a richer blueprint for researchers to investigate the specifics (for instance, measuring fascia tension in a twist, or mapping brain activity during “listening” skills). The common lessons from all these arts could inform fields as diverse as physical therapy (where sensing and balancing are crucial) and robotics (where engineers try to emulate efficient human-like motion). For martial artists, understanding the commonalities fosters respect across styles and opens the door to interdisciplinary learning – a Judo player might learn sensitivity from push-hands, while a Tai Chi player might learn about explosive entry from Judo, all under the umbrella of internal power.

To illustrate, consider the legendary feats of Takeda Sōkaku (Daitō-ryū) and Yang Luchan (Tai Chi), both known for effortlessly defeating larger opponents. Takeda was said to control an opponent with a single finger or a glance, and Yang earned the nickname “Yang Wudi” (Yang the Invincible). In analyzing their skills, we find nothing supernatural – Takeda’s one-finger control was likely an application of perfect leverage on an opponent’s structure (biomechanics), combined with threat perception manipulation (psychology). Yang’s invincibility lay in his supreme timing and connection – reports say opponents simply could not land a solid blow on him, while they found themselves falling at the slightest touch from Yang. This echoes the principles of yielding and immediate counter – essentially, Yang had mastered knowing exactly when and where to apply four ounces to move a thousand pounds. Both masters, though from different cultures, demonstrably converged on using balanced, rooted stances, relaxed power, and superior timing to nullify brute force. Today, using tools like slow-motion video, pressure sensors, and electromyography, we could in theorycapture what they were doing in measurable terms – how quickly did Takeda sense and react to a push? How much force did Yang’s subtle redirection actually put on his opponent’s center of mass? Doing so not only satisfies curiosity but also helps current practitioners replicate those results more reliably by focusing training on the key factors.

Toshu Kakutō (徒手格闘), the term for “unarmed combat” used in modern Japanese military combatives, exemplifies how these traditional principles have been integrated into a contemporary, eclectic system. The Japan Self-Defense Forces’ combatives program (Jieitaikakutōjutsu) incorporates techniques from judo, karate, aikido, and even Western boxing and wrestling (Jieitaikakutōjutsu – Wikipedia). In creating this program, developers found that certain foundational principles allowed techniques from various sources to work seamlessly together – those principles are essentially the internal ones: balance control, core power, timing, and targeting anatomical weak points. Military instructors have noted that teaching soldiers to “feel the opponent’s balance” or to “strike with the whole body’s weight” dramatically improves effectiveness compared to teaching isolated tactics. This is a direct carryover from the internal martial traditions. It underscores that the human body operates under the same rules no matter the context – be it a samurai duel or a modern military encounter – and thus the accumulated knowledge of internal principles remains extremely relevant. In essence, Toshu Kakutō and similar modern systems confirm by reverse-engineering that the traditional masters got it right: the most efficient way to disable an opponent is to use their force, your structure, and impeccable timing – not sheer strength. For instance, a modern MMA fighter might unknowingly use internal principles when “posting” a arm to avoid a takedown (structural alignment) or when rolling with a punch to lessen its impact (yielding/neutralizing) and then counter-punching (issuing at the right time). By studying internal arts explicitly, modern fighters and coaches can refine these implicit strategies and perhaps gain an edge through greater efficiency or injury prevention (since internal methods avoid clashing forces unnecessarily).

In summary, the comparative analysis shows that while outward techniques differ (a tai chi slow push vs a jujutsu throw vs a wing chun punch), the internal mechanics share a common DNA. Balance, alignment, relaxation, whole-body connection, timing, and intent form that core. Traditional descriptions (like “spirit to spine, qi to elbow” in Chinese, or “use heart, not force” in Japanese) allude to these same elements. Scientific language lets us explain them – and in doing so, demystify without disrespecting the arts. Instead, it elevates our appreciation: these arts are sophisticated sciences in their own right. By uniting their insights with modern research, we gain a fuller understanding of human potential in movement.

III. Scientific Framework

To translate the traditional concepts of Huajin and Fajin into modern science, we examine several key scientific domains: fascia and tensegrity (connective tissue biomechanics), classical mechanics and kinesiology (physics of movement and body mechanics), neuroscience (proprioception, motor control, and brain adaptation), and other medical sciences (connective tissue physiology, the autonomic nervous system, etc.). Each provides a piece of the puzzle in understanding internal martial arts power. Below, we outline how each framework relates to and illuminates the martial principles discussed.

Fascia & Tensegrity

Fascia is the continuous connective tissue web that surrounds and interpenetrates muscles, bones, nerves, and organs. If muscles are the engines of movement, fascia is the transmission that distributes forces throughout the body. In recent years, fascia science has shown that this tissue can transmit significant force between body parts without involving muscle contraction. For example, force transmitted along myofascial chains (like the back line or spiral line) has been demonstrated in cadaver studies and in vivo: one study found that tension in the hamstrings could transfer force to the lower back via fascia, and that the latissimus dorsi and contralateral gluteus maximus are linked by the thoracolumbar fascia, allowing force transfer across the back ( Intermuscular force transmission along myofascial chains: a systematic review – PMC ). This directly supports the martial concept of whole-body power – a punch truly isn’t “just an arm,” it’s legs and hips pulling on fascia that move the shoulder and arm. Traditional exercises like silk-reeling in Taiji or dragon twisting in Bagua explicitly train these fascial spirals. Fascia’s elastic property also explains how energy can be stored and released (as in fajin). When you stretch fascia (by elongating or twisting the body), it accumulates potential energy like a stretched rubber band, which can then recoil to contribute to the strike, augmenting muscular force.

Equally important is the concept of biotensegrity as it applies to the human body. Tensegrity (tensional integrity) is a structural principle where a system achieves stability by balancing continuously tensed and discontinuously compressed elements. In the body, muscles, tendons, and fascia create continuous tension, while bones act as isolated compression struts. Unlike a column (which is continuous compression) or a cable (continuous tension), a tensegrity structure can absorb and distribute forces very efficiently. If you push on a tensegrity model, the stress distributes throughout the structure rather than focusing on one joint. This resonates strongly with internal martial arts teachings. When masters speak of the body being “as one” or maintaining Peng jin (expansive stability), they are describing what could be seen as a tensegrity state – the body is springy and unified, not collapsing at any single point. A Wing Chun internal expert described it thus: “each center of weight of each segment becomes connected to every other segment’s center of weight via the tensile materials of the body (fascia, ligaments, tendons, etc.)” ([

        Biotensegrity in Wing Chun Kung Fu 
    
    | Nim Tao Wing Chun
](https://nimtaowingchun.com/blog/single?id=5#:~:text=match%20at%20L153%20Biotensegrity%20implies,being%20fascia%2C%20ligaments%2C%20tendons%20etc)). That is a perfect description of tensegrity in human form. The benefit of such a state is twofold in combat: **resilience and force transmission**. Resilience means if someone pushes or strikes you, the force is spread through the fascial network and dissipated – your body “gives” where needed but as a whole remains intact (yield but not collapse). Force transmission means when you want to deliver force, that same network allows all parts to contribute; the push of your foot is conveyed through the tensegrity grid to your fist. Anatomy Trains author Thomas Myers famously notes that fascia connects “head to toe, fingertip to toe-tip” forming continuous lines ([Tai Chi, Fascia & Biotensegrity - The Internal Athlete™](https://theinternalathlete.co.uk/2023/02/24/tai-chi-fascia-and-biotensegrity/#:~:text=Tai%20Chi%2C%20Fascia%20%26%20Biotensegrity,and%20even%20every%20nerve%20fibre)). Indeed, a healthy, trained fascial system can make movements more integrated. Internal training often emphasizes slow, controlled motion (like Zhan Zhuang or slow form practice) specifically to engage fascia. Slow movements with load encourage fascial remodeling – the collagen fibers line up according to strain, thickening in response to repeated stress. Over years, an internal artist’s fascia becomes exceptionally well-developed (some call this “tendon strength”). This might explain feats like bending spears with the throat or breaking stones on the body – the fascia forms a protective, power-transmitting sheath. 

Tensegrity models help us understand odd phenomena like how some masters can seemingly issue force without wind-up. If the body is pre-stressed (tensegrity structure already loaded), a very small contraction can change the tension balance and result in a big movement – akin to plucking a tense string. If everything is slack until you move, you have to take up the slack first (slower, less efficient). Internal training maintains a background tone (not full tension, but slight engagement, often called peng or expansive force in Taiji). Think of it as keeping the body’s slack out without being stiff – a tensegrity structure under prestress. Then power can manifest instantly in any direction. A Western analogy is an animal like a cat: its body at rest is supple but springy; when it moves, power explodes in a flash. Biotensegrity research posits that even at micro levels (cells and molecules) our body uses tensegrity – it’s a scale-free principle (The human body is organized in nested tensegrity networks formed micro… | Download Scientific Diagram) (The human body is organized in nested tensegrity networks formed micro… | Download Scientific Diagram). So training tensegrity is really training the body at all levels to share load and coordinate.

In summary, fascia and tensegrity science validate many internal art claims: that the body can be trained into a connected, springy whole (rather than just separate muscle groups). It provides a structural basis for how internal force is stored, transmitted, and released. When an adept “connects their entire body,” we can envision their fascia network engaging like a tuned web. When they “sink their qi to dantian,” we can imagine them adjusting the tensegrity balance to a lower, more stable set point (like lowering the center of a tensegrity ball). When they “emit force from the entire body,” it is literally true: through fascia, a push with the foot can involve muscles in the back, abdomen, and arm in one coordinated pull – something measured in labs as kinetic linkage. Fascia research also sheds light on the importance of relaxation: a chronically tense muscle or fascia segment (say due to stress or injury) breaks the tensegrity harmony, acting as a snag that prevents smooth force flow. That’s why internal arts put huge emphasis on stretching, loosening exercises and deep relaxation; these help restore fascial pliability and uniform tension distribution. A fascinating area of fascia science is its neurosensory role – fascia is loaded with proprioceptors. So a lot of our body awareness actually comes from fascia (not just muscle spindles). This again ties to tingjin (listening skill); by training slow movements and static holds, internal artists likely increase fascia’s sensitivity and their brain’s ability to interpret fascial feedback. Thus, fascia is both a mechanical and sensory foundation for internal power. As research progresses (e.g., advanced imaging of fascia in motion), we expect to directly observe how a Tai Chi push or a Karate punch engages these connective tissue networks. Already, ultrasonography has been used to watch fascia sliding and stretching. One could imagine a study where a master performs a fajin and we see certain fascial chains “ping” taut at the moment of impact. That would visually confirm what internal lineage holders have passed down through metaphor and tactile feel.

Biomechanics & Kinesiology

This framework covers the classic physics of movement: forces, levers, momentum, center of mass, etc., as well as the anatomical mechanics of joints and muscles. Internal martial arts, when distilled, are a masterclass in applied biomechanics. We’ll break this down into subtopics:

Kinematics and Kinetic Chains: Human movement is generated by a series of joint rotations and translations. In a strike or throw, what matters is how these combine. As noted, internal arts insist on sequences that start from the ground and move upward (or outward). Biomechanically, this is optimal because larger, slower muscles (legs, hips) initiate, and faster, more refined segments (arms, hands) finalize – creating a whip-like effect. The biomechanical assessment of fajinstudy explicitly found “maximum joint angular velocities and peak muscle activations occurred in a fixed sequence”among trained individuals (Archives of Budo – Abstract). This sequence was foot → knee → hip → torso → shoulder → arm, essentially. If one segment fires out of order, power is lost or the movement feels clunky. Thus, a punch generated by arm then torso then legs (reverse order) would be far less effective. Traditional forms essentially program the correct sequencing by their choreographed transitions. Kinesiology also examines joint angles: internal arts often use mid-range joint angles where muscles can produce the most force (not overextended or too contracted) – for example, a typical elbow angle in a push is around 120 degrees, where one can push strongly, rather than near 180 (locked) or 30 (very bent). Stances like the bow stance in Tai Chi or front stance in karate position the knee not too far forward or back, optimizing the ability to push off the ground. We can see these as the artists discovering the ideal joint alignments for force.

Center of Mass and Balance: Martial techniques revolve around controlling the center of mass (COM) – both one’s own and the opponent’s. In throws, you want to elevate the opponent’s COM or move it beyond their base. In strikes, you want to deliver force through your COM into theirs without losing your own balance. Biomechanics teaches us that when two bodies interact, momentum is conserved; internal artists are masters at borrowing momentum from the opponent and adding to it. For instance, in a shoulder throw, as the opponent pushes, you turn and drop – his momentum carries him over. From a teaching perspective, many internal drills (standing on one leg, moving slowly, weapons forms) train awareness of COM. In engineering terms, the body is a multi-link pendulum; martial arts train how to stabilize that pendulum quickly (stance) and how to destabilize another’s. Inertia: internal fighters learn to use their body weight effectively. Dropping one’s weight at impact (called “earth power” in some styles) means your mass is fully contributing. In physics, Force = mass × acceleration; if you increase effective mass by committing body weight, you need less acceleration to produce the same impact. Traditional breaking demonstrations (like breaking a board with a short range strike) are often done by syncing body mass drop with arm strike. A small acceleration with large mass can equal a fast punch with only arm mass. Internal training emphasizes moving the body’s center together with the strike (even if subtly). Boxing and Muay Thai do this too, but internal arts make it an explicit principle (e.g., “when one part moves, all parts move”).

Leverage and Torque: Many joint-locking or throwing techniques hinge on applying force at a leverage disadvantage for the opponent. A slight twist of the wrist can control the whole arm if applied correctly – this is using a long lever (the forearm) against a weak joint (the wrist). Biomechanics calculates torque = force × lever arm. Traditional jujutsu figured out countless ways to maximize lever arm (and thus torque) while minimizing input force. Internal power in locks often involves positioning your body such that your weight provides the force on the lever, not just your arm strength. For example, standing aligned and dropping your body can apply huge torque on someone’s elbow if you’re holding their wrist – essentially you’re delivering the force of your bodyweight × gravity × lever distance on their joint. That’s a lot more than just muscle force. In strikes too, leverage appears: hitting to rotate someone around their center (like a roundhouse kick to ribs) can be seen as trying to impart rotational acceleration (which if they can’t compensate, leads to a KO or off-balancing). Traditional text might not say “torque,” but say “strike the waist to twist the torso,” which is the same idea. A scientific approach can precisely measure these things (force plates for linear, transducers for rotational force). Some studies in judo have measured the off-balancing forces and found correlations with successful throws. Notably, techniques like the seoi-nage throw involve creating a fulcrum with one’s back and pulling the opponent’s arm – classical lever mechanics at play.

Muscle Activation & Strength Curves: While internal arts de-emphasize brute strength, muscle strength is still a factor, especially in maintaining structure and executing explosive movements. Internal training tends to focus on eccentric strength (ability to yield under load without collapsing) and isometric strength (holding postures). Zhan Zhuang (standing) is essentially an isometric exercise – muscles work to hold a pose, often just below their maximal contraction, for extended time. This builds endurance and static strength that help maintain structure under stress. It’s akin to a plank exercise but encompassing the whole body. Eccentric strength is trained in push-hands or sparring by resisting pushes lightly or giving way under control – the muscles learn to lengthen while under tension. This is critical to avoid injury and to execute throws (where your legs often do an eccentric contraction as you lower with the opponent). Scientifically, eccentric training is known to increase tendon stiffness and musculotendinous strength significantly. So internal arts inadvertently use advanced strength training methods but embedded in their practices.

One can also look at ground reaction force (GRF) data in martial movements. For example, when a Tai Chi master does a fajin push, the force plate under their rear foot might show a sharp spike as they drive off, and the front foot might show a bracing force on impact. Measuring that would quantify how much force is coming from the ground. Preliminary studies have indeed looked at GRF in Tai Chi and found that experienced practitioners can generate substantial horizontal GRF even in slow movements due to coordinated weight shifts (Archives of Budo – Abstract) (). If we measure a boxer’s punch, we also see GRF spikes in the rear leg – universal. The difference is internal arts make the practitioner very aware of this, thereby often improving their efficiency in using it.

Momentum and Impulse: Impulse (force × time) is another concept relevant to fajin. A very short, high force (impulse) can cause displacement. Masters often focus on very brief contact – the idea of “short power.” In physics, delivering the same momentum in a shorter time means higher force. Training short power (one-inch punch, etc.) is essentially learning to maximize impulse by minimizing time of contact. Bruce Lee’s famous one-inch punch is a great example: he used hip snap and wrist snap over maybe 0.1 second of contact to transfer momentum to the target, launching a person back. Internal training like Xingyi’s half-step bengquan or Bajiquan’s explosive strikes aim for that – a lot of momentum transfer in a blink. Science can measure strike forces and durations; indeed high-speed cameras and force sensors show that experts have shorter contact times than novices (meaning their hits are “sharper”). This aligns with the traditional notion of crisp technique versus a pushy, slow technique. Conversely, when the goal is to throw the opponent rather than concuss, sometimes a longer force application (a push) is better – here internal arts ensure it’s done in a way that the opponent cannot recover balance during the longer push (hence continuous following). Impulse applied over longer time but in the right direction (as in push-hands, where you might keep pressure on until the opponent is out of bounds) is also an optimization problem – and practitioners learn to adjust the force continuously based on feedback (something a modern closed-loop control engineer can appreciate).

Joint Health and Longevity: It’s worth mentioning that internal mechanics often aim to minimize wear-and-tear on the body while maximizing effect on the opponent. Alignments that protect one’s joints (like not hyperextending) and using structure instead of muscle reduce injury risk. Modern sports biomechanics often tries to correct athletes’ form to prevent joint injuries – many of those corrections mirror what traditional martial arts already do

Prompted by Jelaludo in Tokyo, Made by Deep Research in California, March 2025