Introduction
I have been offering Rolfing sessions since June 2015. Working with the fascia is how the body’s posture comes into order. The postures Rolfing looks at are three: walking, standing, and sitting.
Gravity is pulling on us, and yet we hold a posture. How is that possible? I want to work through it here by way of proprioception and the vestibular sense, the muscle spindle, and the gamma motor nervous system.
This piece was written in February 2024 and has since been combined with two others from around the same time. What gravity is, seen from physics, and how the three information-gathering systems work — those were added.
What is gravity, to begin with? — Ancient Greece
Everyone on earth feels gravity. It is so ordinary that we rarely give it a thought. But how does physics understand it? What follows draws on Hirosi Ooguri’s Jūryoku to wa Nani ka — “What Is Gravity: From Einstein to Superstring Theory, Approaching the Riddles of the Universe” (in Japanese).
The history of gravity begins in ancient Greece. Aristotle held that matter has a tendency to return to its proper place. A stone thrown upward returns to where it belongs, the ground — and on this view no force is at work.
Aristotle explained the world through four elements — fire, air, earth, and water — and supposed that a body with more earth in it would return faster toward the center of the earth. The heavenly bodies, meanwhile — sun, moon, stars — repeat periodic motions and have no proper place to return to. The heavens, he held, were made of a fifth element and governed by laws other than those of the ground.
Isaac Newton — gravity made systematic
Aristotle’s picture held until the Middle Ages, and then Newton arrived.
He defined force as what changes the motion of a body, and set it out systematically as mechanics.
1. With no force acting, the motion of a body does not change (the law of inertia)
2. When a force acts, direction or speed changes (the law of motion)
3. Where there is a push, a push back is generated (action and reaction)
With this, a body falling to the ground could be explained by the working of a force. The motion of the stone changes by way of a force — the earth’s attraction — which is gravity.
Gravity has five features worth setting out.
① Gravity works the same on the ground and in the heavens
What is remarkable in Newton is that he showed gravity to be universal — working in common on earth and in the heavens. The sun, moon, and stars attract one another, and it is by this that they move. Ground and heaven are under the same force, and with that the two were unified in theory.
② Gravity is weak compared with electricity and magnetism
What is interesting is that Newton could not explain why force arises. It took until the end of the eighteenth century — a hundred years — for experiment to demonstrate that gravity works between material bodies on the ground.
The reason it took so long is that gravity is a weak force — weak, that is, compared with electricity and magnetism. Put a magnet under a table and something will hold against gravity without falling. The relative strength is available to the senses.
If it is weak, why do we register gravity at all? Because gravity is said to have only attraction, with no repulsion. Electricity and magnetism have both.
③ Gravity works at a distance
Gravity moves bodies that are far away. Ordinarily, to move something you have to touch it — push it by hand, transmit force through gears. Magnets and gravity are different: they move things at a distance. A remote control and a television work this way.
People once found action at a distance mystical, and held that no such thing could exist. Yoshitaka Yamamoto’s Jiryoku to Jūryoku no Hakken — “The Discovery of Magnetism and Gravity” (in Japanese) — traces historically how the idea of gravity came to be accepted as understanding of magnetic force deepened. It is a fine study of how action at a distance found its way into general acceptance.
④ Gravity works equally on all matter
Heavy things and light things reach the ground at the same time, which means gravity works equally on all matter. One would expect a heavier body to be pulled harder by the earth, and yet, where there is no air resistance, bodies fall at the same rate regardless of weight. The reason is that resistance to being moved — mass — and the strength of gravity cancel each other exactly.
⑤ The theory of gravity is still under way
The theory advanced with Einstein’s general relativity. Mass curves space; the curvature of space is what produces the attraction we call gravity; and not only space but time and light curve as well. Beyond that, much remains unknown, and a unified theory including gravity has yet to be established.
We human beings, from the moment we are born, feel gravity first of all. We build a relationship with it, and as we develop from fetus to adult, posture comes into order. So: under that gravity, how does the body hold a posture?
Posture and the human being — from postural reflex to proprioception, the vestibular sense, and vision
Between 1915 and 1930, Sherrington and Liddell showed that standing involves antigravity muscles, which work against gravity so that the body is not crushed by it, and that these muscles are governed by the postural reflex, which holds posture appropriately and works reflexively.
By 1934 it was established that the postural reflex is determined by the work of the brain — the brainstem and the cerebellum — and the relationship between posture and the postural reflex appeared, for a time, to be settled.
From 1986, the importance of proprioception, the vestibular sense, and vision in maintaining postural balance also came into view. Proprioception and the vestibular sense in particular, according to Takashi Haitani’s Ningennō o Sodateru — “Growing the Human Brain: The Development of Movement and the Maturing of Primitive Reflexes” (in Japanese) — are tied to the cultivation of the unconscious.
That vision bears on posture is easy enough to follow. Proprioception and the vestibular sense are harder to get hold of, so let me introduce them by way of Haitani’s book, which puts bodily sensation into words well.
Proprioception — the sense that tells you where you are
Proprioception conveys the movement of joints and muscles to the brain. For posture, it senses where every part of the body is — fingertips, soles, knees. According to Haitani, when proprioception is weak, judging distance from obstacles becomes difficult and one bumps into things; it bears on how one gauges distance from other people; and it is the sense that tells you who you are and where you are.
The vestibular sense — awareness of one’s own central axis
The vestibular sense is what holds the body upright. Bringing the body’s central axis into order is what makes it available to awareness. Recovering this sense is one of the aims of the ten-series. According to Haitani, being able to use one’s body freely within gravity is what leads to putting one’s capacities to work.
He adds that without it, one cannot gauge how much muscular force a given activity calls for. People who struggle with reading, writing, and listening, he notes, often have markedly weak neck muscles and find it hard to control their own muscles unconsciously.
How brain and body talk to each other — instructions to move, and gathering information
Here it is worth looking at how the body gathers information.
Mind and body are connected, as people often say. The brain and the body are in close communication. And the information traveling from body to brain, and from brain to body, has two functions respectively: gathering information, and issuing instructions to move.
Muscle handles both of these, and cannot do them at the same time. Tension arises as rigidity produced by the instruction to move. Let a muscle concentrate on gathering information and the tension resolves of its own accord — this is what Rolfing checks for.
The three information-gathering systems
The body has three “information gatherers”: the visual system, the inner-ear sense (the vestibular system), and the kinesthetic sense (proprioception). Activating these puts gathering information in the lead, and tension resolves.
These are the same three as above, but in the session room these are the names more commonly used. I will use them from here on.
The first system — the kinesthetic sense
The kinesthetic sense is what conveys external information — from hands, feet, head, face (together, the external sense organs) — into the interior of the body. In Rolfing, what gets examined is mostly the sensation in the muscles of the hands and feet.
The more readily hands and feet can receive information — the more freely fingers and toes move — the more readily the body comes into order. With age, muscles and joints weaken and movement becomes harder, and the kinesthetic sense declines with it.
One simple way to check is to hang from a bar and see how long you can hold. In longevity research, there is a view that takes two minutes for men and ninety seconds for women, at the age of forty, as a rough benchmark (Peter Attia, Outlive). The benchmark comes down with age.
Yoga has an exercise called sukshma vyayama — sukshma meaning fine or subtle in Sanskrit, vyayama meaning exercise. The joints of the hands and feet are moved in time with the breath, slowly, carefully, with attention on the body, and hands and feet become free to move (opening and closing the hands, moving the heel and each toe one at a time).
This is an exercise for the kinesthetic sense, and it matters for raising awareness of sensation. For anyone who has no awareness of their own bodily sensation at all, this kind of exercise is effective.
The second system — the inner-ear sense
The inner-ear sense is the sense of equilibrium. What feels gravity is the inner ear, deep in the ear. Working together with the brain, it senses which way the body faces, its tilt, and its movement.
Standing on one leg for thirty seconds with the eyes open, and fifteen seconds with the eyes closed, is a rough benchmark commonly used for looking at balance. It offers a way into examining this sense.
The third system — vision
Vision gathers what comes in through the eyes. This sense is the easiest to follow, but there is one difficulty with it. According to Rita Geirola, one of the Rolf Movement instructors:
Human beings learn to see through education and experience.
So: the inner-ear sense and the kinesthetic sense are there from birth, while vision is learned through experience and education, which makes it the easiest of the senses to be aware of. And that is why it most readily takes the lead.
What the foot’s kinesthetic sense does — between vision and the inner ear
What is interesting is where vision and the inner-ear sense sit. The eyes are at the front of the face, the ears behind them. So using vision carries the center of weight forward, toward the toes; using the inner-ear sense carries it back, toward the heel. In holding the balance between the two, the kinesthetic sense of the foot plays a considerable part.
What matters in standing is where the foot sits. At the start of a session I look at whether weight falls toward the heel or toward the toes, and at the end I look at how that has changed.
What is interesting is that the sense of the eyes, being the easiest to be aware of, tends to grow stronger. And as it does, the working of the inner-ear sense — and gravity itself — becomes harder to feel. Vision connects back to the occiput, so overuse of the eyes ties into stiffness in the neck and shoulders.
In my own case, work revealed that if the left eye’s field is 100 and spherical, the right is 60 and slightly weighted toward the rear. Closing the left eye and using only the right produced a sense of constriction in the chest. When a partner made a sound at the outer right side of my head to activate the inner-ear sense, the right eye’s field widened and the constriction cleared.
Rolfing works at the root of the balance between vision and the inner-ear sense, which is why stiffness in the neck and shoulders tends to ease.
The muscle spindle and the gamma motor system — holding a posture at low cost
These three senses convey information to the nervous system, which then sends instructions to the muscles involved in posture. Here too there was a significant finding.
In 1986, the relationship between posture, the gamma motor nervous system, and the muscle spindle came into view.
The muscle spindle is the muscle’s sensor, a sensory organ that detects the stretching and shortening of the muscle. Anyone who has been to a yoga or meditation class has heard the instruction to be aware of the body. What switches on at that moment is the muscle spindle.
When the body detects gravity, the spindle switches on more readily, so that the continuously working muscles, rich in spindles, can move unconsciously without gravity being attended to. That the three senses can work unconsciously is owed to the spindle.
For the postural muscles to work, instruction from the nervous system is needed. These are the motor nerves, of which two are known: the alpha motor system and the gamma motor system.
The alpha motor system (two-thirds of the motor nervous system) works by way of the brain, and so acts on muscles moved consciously. It is used in sprinting, weightlifting, lifting objects. Under gravity these muscles work transiently and tire easily. Stiff shoulders and lower-back pain are likely cases of the transient, easily tired muscles doing the work of holding posture.
The gamma motor system (one-third) is governed less by conscious direction than by the cerebellum and medulla oblongata, which handle the unconscious and the habitual, and it acts on the continuously working muscles, rich in spindles, under gravity. These resist fatigue, and for holding posture they are the muscles one would want at work.
Put this way, it becomes clear that holding posture by way of the muscles that do not tire is what matters. Or: how to activate the gamma motor system and make the fullest use of the energy-efficient, continuously working muscles.
Activating the gamma motor system — using the hands and the feet
The key to activating the gamma motor system is having the kinesthetic sense available.
When the hands and the feet are properly in use — the whole palm, and the whole foot including the arches — the deep postural muscles along the spine steady.
For instance, taking a pose on a yoga mat (downward-facing dog, say) with the whole palm suctioned to the mat without effort brings the serratus anterior, the rhomboids, and the deep muscles joining the spine into use. These deep muscles are the continuously working ones, and this is how the gamma motor system gets activated.
The ten-series is built around how to activate the gamma motor system and make the fullest use of the energy-efficient, continuously working muscles, and is arranged so that awareness of the kinesthetic sense in particular can be raised.
Conclusion
Gravity is pulling on us, and yet we hold a posture. This piece began with what gravity is as physics understands it, worked through proprioception and the vestibular sense, the muscle spindle and the gamma motor system, and set out how to attend to the body in order to hold a posture at low cost.
If this interests you, a session is a place to begin (a trial session is also available).
Note, September 2026
This piece explains gravity twice.
The first time from the side of physics. Aristotle, Newton, Einstein. That it has only attraction and no repulsion, that it works on bodies at a distance, that it works equally on all matter. The second time from the side of neurophysiology. Antigravity muscles, the postural reflex, the muscle spindle, the gamma motor system.
Both are frameworks from outside myself. What a physicist wrote, and what physiologists found. I borrowed them to explain what happens in the body.
One year and three months later, in the 2025 advanced training, gravity was handled differently.
Jeff Maitland’s notion of orthotropism runs as follows. Just as a sunflower naturally rises toward the sun, the human body holds within it a force that seeks to rise upward in harmony with gravity. Rolfing’s part is to support that without getting in its way (see “Journey to Becoming an Advanced Rolfer — A Summary of the Road to Certification“).
Here, gravity is not explained. What kind of force it is goes unasked, and what is set down is only the relation — that the body rises toward it.
From something to be explained, to something to be entrusted with. Toward the same gravity, the stance has shifted.
What I wrote in 2024 is not wrong. The physics side and the neurophysiology side both stand. It is only that, at the time of writing, I took explaining something to be the same as understanding it.
One more part of this piece has been revised.
The seconds for hanging from a bar were originally written as an “ideal.” On checking the source, they turn out to be a benchmark used in longevity research, and they are the figures for age forty. They come down with age. I had written the figures while dropping the condition attached to them. The seconds for standing on one leg have been rewritten as a benchmark in the same way.