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| Internal power |
Internal Power in Kung Fu: Tradition and Biomechanics
Few expressions in Chinese martial arts create more confusion than “internal power.”
Ask ten practitioners what “internal” means and you may receive ten different answers.
One person will talk about qi.
Another will talk about relaxation.
Another about fascia.
Another about skeletal alignment.
Someone else will describe intention, breathing, the dantian, whole-body movement or the ability to generate power without obvious muscular effort.
Occasionally the explanation becomes even more mysterious: internal power is presented as something fundamentally different from ordinary human movement, available only through secret training.
There is a problem with all these discussions.
Before asking whether internal power works, we first have to ask:
What exactly are we talking about?
“Internal” Is Not One Thing
The modern English expression “internal martial arts” can hide several different concepts.
The historical Chinese classification 內家 (neijia) has its own history.
Later martial artists used concepts associated with 內功 (neigong).
Traditional Chinese theories employ concepts including 氣 (qi), 意 (yi), 勁 (jin) and 丹田 (dantian).
Modern practitioners then added explanations involving anatomy, biomechanics, fascia, nervous-system function and sports science.
These vocabularies should not automatically be treated as interchangeable.
If an old text talks about 氣, we should first ask what 氣 meant within that text.
We should not silently replace it with “oxygen,” “bioelectricity,” “fascia” or “neuromuscular coordination.”
Likewise, if modern biomechanics explains an observable movement, that does not demonstrate that an eighteenth-century martial artist secretly understood twenty-first-century physiology.
Traditional explanation and modern scientific explanation are different analytical layers.
They can be compared.
They should not be confused.
Does Internal Movement Use Muscles?
Yes.
Every voluntary martial movement requires muscular activity.
There is no special category of human movement that operates independently of the musculoskeletal and nervous systems.
When someone pushes, punches, steps, turns, throws or lifts an arm, muscles generate force.
But this does not mean every way of generating force is equally efficient.
That is where the discussion becomes interesting.
The important distinction is not:
muscles versus no muscles.
It is:
how are the muscles being used?
Relaxation Does Not Mean No Muscular Activity
Traditional martial teachers frequently tell students to “relax.”
This instruction is easily misunderstood.
Complete muscular relaxation would make purposeful posture and movement impossible.
A standing human body already requires muscular activity.
What martial artists usually seek is not the elimination of muscular activity but the elimination of unnecessary muscular activity.
Imagine throwing a punch while simultaneously contracting muscles that oppose the movement.
The body is effectively fighting itself.
Some muscles accelerate the limb while others unnecessarily resist it.
The movement feels strong because enormous tension is present, but much of that effort contributes nothing useful to the intended action.
A skilled movement can feel considerably more relaxed because muscular activation is better coordinated.
The necessary muscles work at the necessary moment.
Unnecessary resistance is reduced.
That is very different from saying:
“Muscles are not being used.”
What About Tendons and Fascia?
Modern internal-martial-arts discussions often swing to the opposite extreme.
Instead of muscles generating power, we are told that tendons, ligaments or fascia generate it.
Again, the human body is more interesting than this simple opposition.
Muscles generate active force.
Tendons transmit muscular force to the skeleton and can also store and return elastic energy.
Connective tissues contribute to the mechanical behaviour of the body.
Joints, bones and their geometrical relationships determine how forces are transmitted.
The nervous system coordinates everything.
None of these structures operates independently.
A useful martial movement is therefore not produced by discovering one magical tissue responsible for power.
It emerges from the coordinated behaviour of the entire system.
The Body Is a System
Consider a simple push.
The hand contacts another person.
But the hand alone cannot explain what happens.
Forces interact through the wrist, elbow and shoulder.
The torso influences the position of the shoulder.
The pelvis influences the torso.
The legs interact with the ground.
Joint positions affect the directions in which forces can be produced and resisted.
The nervous system continually adjusts muscular activity to maintain balance and accomplish the task.
Changing one part changes the behaviour of the whole system.
This gives us a useful way to interpret something traditional martial artists often describe as whole-body power.
It does not require mysterious energy travelling through the body.
But neither is it simply “using bigger muscles.”
It is a coordination problem.
Local Power and Whole-Body Power
Suppose a beginner tries to push someone using primarily the shoulder and arm.
The movement may involve substantial muscular effort but poor coordination with the torso and lower body.
Now an experienced practitioner performs the same task.
The foot position, legs, pelvis, torso, shoulder, elbow and hand contribute to a coordinated action.
The second practitioner may appear to be working less while producing a better result.
This can create the subjective impression of unusual power.
But nothing supernatural has happened.
The body has simply become better organized for the task.
This is where I think modern biomechanics can provide a useful model for understanding some of what martial artists describe as internal skill.
Practitioner Analysis
In my own training, I find it useful to think about internal power as a problem of coordination and efficiency rather than a separate source of force.
The goal is not to eliminate muscular force.
The goal is to organize muscular force through appropriate structure, timing and whole-body coordination while minimizing unnecessary tension.
This is a model.
I am not claiming that this modern biomechanical interpretation defines every historical meaning of 內功, 氣 or “internal.”
Sequence Matters
Power generation is not merely a matter of arranging the body into a particular static posture.
Timing matters.
Different parts of the body must contribute at appropriate moments.
A movement can have apparently correct positions and still function poorly because muscular activation and joint movement occur in an inefficient sequence.
This is one reason traditional exercises often involve slow repetition.
Slow practice can give the practitioner time to examine alignment, tension and coordination.
But slow movement alone does not create internal power.
Eventually the organization has to survive increasing speed, load, unpredictability and resistance.
Otherwise we have learned to perform an exercise rather than developed a transferable physical skill.
Structure Is Dynamic
“Structure” is another word that martial artists sometimes treat too mechanically.
The human body is not a building.
A building's structure is designed primarily to remain stationary.
A fighter's structure must continually change.
We step.
Turn.
Accelerate.
Absorb force.
Redirect force.
Lose balance and recover it.
Interact with another moving human being.
Good martial structure therefore cannot simply mean arranging bones into one perfect alignment.
It means maintaining useful mechanical relationships while conditions change.
That is considerably harder.
Where Does Qi Fit?
Traditional Chinese martial arts frequently explain training through 氣.
We should neither automatically accept qi as a measurable physical substance nor dismiss centuries of Chinese terminology as meaningless superstition.
The better question is:
What does qi mean in this particular source or practice?
In one context it may relate strongly to breathing.
In another to health.
Elsewhere it may form part of a traditional cosmological or medical model.
A martial teacher may use the word to describe a subjective quality of coordinated movement.
Different historical uses need not refer to exactly the same concept.
Modern physiology can investigate measurable phenomena associated with these practices—breathing patterns, muscular activity, balance, force production, cardiovascular responses and so forth.
But demonstrating one of these mechanisms does not establish:
“Qi really means biomechanics.”
That would simply replace one oversimplification with another.
So What Is Internal Power?
There are really two answers.
Historically
“Internal” belongs to a complicated history of Chinese martial terminology that cannot be reduced to one universal definition.
That history deserves to be studied through the texts and communities that actually used those terms.
Biomechanically
We can investigate many abilities described today as internal power using ordinary human physiology.
They may involve:
- efficient muscular coordination;
- reduction of unnecessary co-contraction;
- appropriate joint positioning;
- balance and postural control;
- coordinated movement of multiple body segments;
- effective interaction with the ground and external forces;
- elastic contributions from muscle-tendon structures;
- timing;
- breathing;
- proprioception and sensory feedback;
- nervous-system control developed through practice.
None individually is “internal power.”
Together they can produce movement that feels remarkably different from the uncoordinated force of a beginner.
Internal Versus External
This also suggests that dividing human movement absolutely into “internal” and “external” may create more confusion than clarity.
There are not two sets of physical laws.
An “internal” practitioner and a boxer have the same kinds of muscles, bones, tendons and nervous systems.
Both can develop extremely sophisticated whole-body coordination.
Their training methods and movement strategies may differ, but their bodies operate according to the same biology.
From a modern biomechanical perspective, it may therefore be more useful to think in terms of degrees and types of coordination rather than two fundamentally different kinds of human power.
The Mystery Is Still Interesting
Explaining movement through biomechanics does not make traditional martial arts less interesting.
Quite the opposite.
Learning to coordinate dozens of joints and hundreds of muscles while maintaining balance, responding to external forces and making decisions in fractions of a second is extraordinary enough.
We don't need to add magic to make the human body remarkable.
Nor do we need to discard traditional terminology simply because modern science describes the body differently.
We can preserve the old explanations.
We can investigate what they meant.
We can test the physical methods.
And where modern science gives us a better explanation for an observable phenomenon, we can use it.
The important thing is to keep the categories clear.
Tradition tells us how people understood and transmitted their practice.
Science helps us investigate what the body is actually doing.
And somewhere between those two perspectives, we may gain a much better understanding of what martial artists have been calling “internal power.”
References
1. Zajac, Felix E. “Muscle and Tendon: Properties, Models, Scaling, and Application to Biomechanics and Motor Control.” Critical Reviews in Biomedical Engineering 17, no. 4 (1989): 359–411.
This is an excellent foundational reference for our argument that muscle and tendon have to be understood as an integrated mechanical system rather than competing explanations of movement.
https://pubmed.ncbi.nlm.nih.gov/2676342/
2. Alexander, R. McNeill. “Tendon Elasticity and Muscle Function.” Comparative Biochemistry and Physiology Part A 133, no. 4 (2002): 1001–1011.
Very useful because it directly corrects one mistake in the old article. Tendons really can store and return elastic strain energy; we just shouldn't turn that fact into a claim that “fascia/tendons generate internal power.”
https://pubmed.ncbi.nlm.nih.gov/12485689/
3. Roberts, Thomas J. “The Integrated Function of Muscles and Tendons During Locomotion.” Comparative Biochemistry and Physiology Part A 133, no. 4 (2002): 1087–1099.
Another particularly good source for explaining why “muscle versus tendon” is the wrong argument. Muscle contractile elements and tendons operate together, and tendon elasticity can alter efficiency and mechanical performance.
https://pubmed.ncbi.nlm.nih.gov/12485693/
4. Bojsen-Møller, Jens, and S. Peter Magnusson. “Mechanical Properties, Physiological Behavior, and Function of Aponeurosis and Tendon.” Journal of Applied Physiology 126, no. 6 (2019): 1800–1807.
A more modern review. Especially useful for the statement that muscle and tendinous structures operate as a mechanical system in which forces are transmitted and energy can be stored and released.
https://pubmed.ncbi.nlm.nih.gov/30946635/
5. Latash, Mark L. “Muscle Coactivation: Definitions, Mechanisms, and Functions.” Journal of Neurophysiology 120, no. 1 (2018): 88–104.
Useful for our discussion of “relaxation.” It prevents us from making the opposite mistake and claiming that all antagonist co-contraction is simply wasted tension. Coactivation can contribute to joint stiffness, stability and motor control; efficient movement is more complicated than simply minimizing muscular activation.
https://pmc.ncbi.nlm.nih.gov/articles/PMC6093955/
6. Hall, John E. Guyton and Hall Textbook of Medical Physiology. Elsevier.
For basic skeletal-muscle physiology, neuromuscular activation and contraction. We don't need to cite a research paper every time we say that voluntary skeletal movement involves muscular contraction.
A freely accessible supplementary source is the NCBI overview “Physiology, Skeletal Muscle Contraction.”
https://www.ncbi.nlm.nih.gov/books/NBK559006/
One reference I especially want included
7. Roberts, Thomas J., and Emanuel Azizi. “The Series-Elastic Shock Absorber: Tendons Attenuate Muscle Power During Eccentric Actions.” Journal of Applied Physiology.
More broadly, Roberts' work on elastic tissues is valuable because it demonstrates something important for our article: biological elastic structures don't merely transmit force passively. Elastic mechanisms can store and recover energy and influence force, power and work. A later review summarizes this very well.
https://pubmed.ncbi.nlm.nih.gov/26792339/