Normal Function – I

Pages: 6-21
Year: 1991
Notes on S.I

Notes on S.I.


The premise of Structural Integration as a normative system is economy of function. It starts out from the question: “what movement and posture is most economical?” It shares this premise with several other disciplines. But in contrast to those which deal with the question on the same level – that of function – Structural Integration rephrases the question first on a lower level of complexity, that of structure. The question now reads: “which kind of structure permits most economical function?” Ida Rolf answers this question in an absolute sense by describing in detail what she called “normal structure”. “Normal” means “ideal” in the field of Structural Integration as opposed to “average”. In a strict sense no real structure is “normal” but only closer to or farther away from the ideal.

“Better human functioning” which Rolfing as “a physical method” intends to “produce” (Rolf, p.29) is interpreted here as “easy movement and posture”. “Easy” has other connotations as e.g. “fluid” or “simple” but means basically “with little effort”. Physically, the easiest form of a given movement is that which requires the least amount of energy to be spent; it is “most economical” in this sense. A normal structure making use of its potential for the easiest function spends the least amount of energy of all structures for getting through the day. Therefore, the body has at its disposition the largest amount of free energy to spend as desired. This does not mean that the “most economical movement” is also easy to do. It is on the contrary very demanding on brain and mind.

The natural question arises as: “what does most economical function of a normal structure look like?” In the context of the field of Structural Integration the answer must be in terms of the mechanics and its geometry. It must describe movement as the exact spatial change of the relationships of the aggregate of the body and determine which of the possibilities is the most economical one.

The first reason for the natural question is curiosity. When one makes a profession out of integrating clients’ structures so that they are able to move easier it is obvious that one wonders what the truly easiest way of moving looks like. But there is also a good theoretical reason which justifies curiosity. For, because the structural norm is the blue-print for that structure which permits most economical function, a theory of normal function should verify it- or not. And thirdly, the theory as far as it has been developed is extremely applicable in practice. It has turned out that many structures cannot be integrated by structural work alone and end up disintegrated in the long run. These clients must be shown how their bodies function and how they could or should function to permit truly “easy function”. Structural work alone is not sufficient in these cases because the mechanical regimes their own and the normal one – are qualitatively different. They cannot be improved gradually from one to the other because they are discontinuous.

Physiological Base

To say that muscles cause movement is already setting out on the wrong track. But certainly muscles are necessary for movement and their function needs to be understood.

The smallest “motor unit” consists of a group of muscle cells plus one nerve cell which connects by its axon with the muscle cells. The axon is the extension of one cell, a motor neuron of the central nervous system, located in the cornu anterius of the medulla in the spinal cord.

When the cell membrane of the motor neuron depolarizes, an excitation travels down the axon with great speed. The axon splits into branches near the muscle cells belonging to it, and each of them connects via “end plates” to one muscle cell of the group. All the muscle cells of the same unit contract fully and in synchrony in response to the stimulus received from their axon. They do so only when “excited” by their axon. Otherwise they are passive and relaxed and exert no tension at all.

Contraction is “whip-like”. Active tension rises very fast to a peak, then immediately subsides and falls a little slower. There follows a “refractory period” where excitation is not possible and active tension is zero again. During this time the membrane potential of the muscle cells is built up again, the “battery reloads itself”. The motor unit and the tension it exerts upon stimulation follow the “all-or-nothing principle”.

Contraction usually happens several to many times per second. Activity of the motor unit including the motor neuron is measured by the frequency of depolarisations and therefore contractions per second. The strength of the tension it contributes to overall muscle activity is given by the product of the frequency times the “bulk” of the muscle cells of the group as indicated by its cross-sectional surface value.

In contrast to the motor unit, active tension of the whole muscle is continuous and changes quantitatively. This is because the many units which go to make up a muscle usually don’t contract in synchrony. Overall active muscle tension is called muscle tonus. If it decreases, this means that the frequency with which the motor neura via their axa “excite” their groups of muscle cells decreases.

The frequency of contraction of all the groups of muscle cells, and therefore the tonus of a muscle, is directly proportional to the activity of the motor neura in the spinal cord; the frequency of their depolarizations. This again is modulated and controlled permanently and in many different ways by other nerve cells and centers. But the most important aspect is that this central control always happens in one of two different ways. The motor neura can be stimulated, and they will “excite” their muscle cells with a higher frequency; tonus rises. Or they can be inhibited, and the muscle cells contract less often; tonus decreases.

For biological systems the “inhibitory modality” is more important than the “stimulating” one. This is very much in contrast to the machines we know and which influence our way of thinking so strongly. If driving a car is taken as an example, its speed is largely and sensibly regulated and controlled by stepping on the gas, more or less. A biological system would set and fix the gas pedal pressed far down and modify the speed of the car largely by stepping on the brake pedal more or less.

Energetically the two modalities are sharply divided. Muscle tonus is directly related to energy consumption. The higher it is, the more glucose is burned. So a neuronal stimulation leads to a rise in muscle tonus, and more energy is spent. An inhibition lowers muscle tonus and energy is saved in comparison to the initial state of affairs.

Physical Base

Physical forces manifest as tension and pressure in a body fixed unmoving.

The first step of “dividing the whole into parts”, which is essential for any analysis, selects out of the material body as the first and most important part the fascial net. This is remarkably different from most other fields which divide the body into a set of smaller units which can be put together and combined to produce the whole again in a “digital” manner. In contrast to this, the first division in the field of Structural Integration is “analogue”: the fascial net still represents the whole body. It cannot be broken down further into smaller parts if its main features are to be maintained, which are the focus of the structural approach. “Cutting” the fascial net into smaller parts causes the instant loss of its mechanical properties which depend entirely on its integrity and “connectedness”. As a consequence, the logic of the field says that it is incorrect and misleading to conceive the fascial net as a whole composed of individual fasciae. The names we give fasciae merely indicate certain areas in a “geographical” sense without clearly defined boundaries.

The fascial net is not really a “net” primarily. It consists of two-dimensional fascial membranes which close in on themselves and so lock off compartments, “bags within bags within bags” (Wolf Wagner). The whole body in the structural view is so adequately represented and composed by the fascial net plus the “fillings” of the “bags”. Two kinds of “fillings” must be distinguished: the “hard” and the “soft”. The “hard fillings” are usually called “bones” and are (nearly) non-compressible and non-deformable. Structurally, the primary aspect is the bag, conventionally called “periostium”, which provides and defines the space for its “hard filling”. All the other bags are filled by soft tissue, and the “soft fillings” can be conveniently visualized as “thick water”(1). The bags with “soft fillings” are also (nearly) non-compressible but are deformable over a wide range.

The medium of tension is almost exclusively the fascial membranes as a connected system. Pressure is usually only found in the “hard” and “soft fillings”. Bones probably do not depend much on their fasciae, the periostium, for bearing weight and distributing it to the ground.

But in an integrated body it is not exclusively the bones which carry weight. The bags containing “soft fillings” also bear some of it. They form something like “hydrostatic balloons”. When they are compressed and pressure rises inside, the tension of the fascial bag also rises. Opposed to bones, the capacity of the “hydrostatic balloons” for bearing weight depends very much on a balance of the functioning relationship between the pressure in the “soft filling” and tension in the fascial membrane.

One of the interesting features of hydrostatics is that very small pressure gradients between inside and outside are sufficient to make such waterballoons stable. A difference in pressure is necessary, though. For the whole body it is known that pressure inside the “shopping bag” is a little higher than athmospheric pressure outside. This results in part from muscle tonus which compresses the body concentrically from all sides. But also fascia alone maintains a slight pressure gradient. The “thin elastic sack” (Rolf, p.32) does not fit the “set of blocks” it unsheathes in a completely loose manner. It is wound around it with a little tightness. There must not be too much nor too little, and the fascial membranes must not be too rigid nor too soft to allow fascia to perform its job. It then possesses appropriate “fascial tone” or “span” (Rolf, p.39) which is the condition for the soft “paddings” in the bags to also distribute weight to the ground.

To understand the physics of posture and movement the forces acting on and in the body must be analyzed. Three areas need to be considered.

1. Gravity Field

This is traditionally the first source of forces which must be regarded. Gravity acts to propel or accelerate the body and its parts down toward the ground. In conjunction with and exactly opposed to gravity in its direction is the normal force of the earth which rises up vertically from the ground.

For the whole body, the point of action of the gravitational force is the body’s center of gravity. The point of action of the Normal force is the “support point”. In any kind of posture in which the body is not moving, the two points are on one and the same vertical line, which is the Line. If they are not, movement results regardless of what one does with the musculature.

For the arrangement to be normal(2), “there must be a vertical alignment of each block’s gravitational center; there must also be no rotation or tipping of the segments” (Rolf, p.33). Then we have a “strain-free system”. This means that there exists no gravitationally induced strain in the “elastic sack” of the fascial net. Because on every level the mass of the body is exactly balanced front-to-back and left/right, the normal force of the earth cancels out gravity’s effect completely. In the block model this balance is a stable equilibrium(3). For the segments of a real body only labile or unstable equilibrium is possible. So this arrangement, “neutral stance”, can only be approached but not reached. The term “neutral” refers first and foremost to gravity and indicates the arrangement where maintenance of balance requires no effort. The job is done exclusively and completely by the normal force.

When considering all forces however, overall effort will be definitely greater in “neutral stance” than at the Structural Point for a real body. For, there is usually a lot of strain in the fascial net which results from the second area of consideration.

2. Fascial Net

From the structural point of view it makes sense to define the term “fascia”, in a much more extensive manner than in anatomy, as “the whole of all membranes which are made up mostly of collagen fibers and which possess mechanical relevance”. The term then includes such “membranes” as the periostium, the joint capsule, the peritoneum, pleura, and pericardium, the meninges, the sclera, etc. Only then the total of all fasciae forms a closed network.

Two kinds of disturbances of the fascial net can be distinguished. “Endofascially”, the fascial net is presumed to be present in complete differentiation, with all its “membranous” parts discernable and connected in the right places. Then there will still be too much passive tissue tension in some parts, not enough in others. Some areas of the net will be too rigid, and in differing degrees; others will be too soft. The situation becomes immensely complicated when further considering that the pattern of passive tissue tension depends completely on the spatial arrangement of the body in the gravity field. When one changes, the other will also immediately change, and in its entirety. Purely hypothetically, the “tension status” of the fascial net of a given body could be assessed by bringing the body into “neutral stance”, with all the blocks’ gravitational centers on one vertical and no segmental rotation present. Overall passive tension would be decidedly higher than in easy stance, and this would be reflected directly in the muscular effort necessary to maintain “neutral stance”. But the effect of gravity would be cancelled out entirely and solely by the normal force of the earth. The total amount of tension would be a measure for the degree of structural integrity, and of the distance to the structural norm of the body in question.

Furthermore, the procedure would allow, at least theoretically, to identify the areas of most strain or “shortness”. This permits a view of the process of integrating structure which could be called “natural Rolfing”. The areas of the fascial net most under strain would be made resilient in consecutive steps. Progress would then manifest not in a change of shape of the body – it would be and stay in “neutral stance” all the time – but in a continual reduction of overall tension and therefore muscle effort necessary. This concept is relevant for the theory but not applicable in practice, of course.

Disturbances on another level, “exofascial”, have been assumed to be absent in this description. They are not found within the fascial “membranes” but between them. Fasciae can be glued together, and they often are. This may perhaps take the form of the jellied ground substance keeping the fasciae stuck together, or it may be adhesions with collagen fibers “grown through” binding fasciae together. In any case, such fasciae bunched together must be separated. The result is better differentiation of the fascial net. This is on the second level of the structural hierarchy (Notes on S.I. 89/1, p.42). And this means that differentiation does not automatically indicate integration. Structure can just as well be disintegrated by it, certainly when the glueing and adhesions had a function in maintaining the integrity of the structure, whatever its degree was. Differentiation is often a prerequisite for integration, but in itself it may be disintegrating just as well as integrating.

As far as function is concerned, fasciae exert an elastic force on the body in proportion to how much they are strained. In the “fillings” of the fascial bags pressure or compression is found. It also exerts a force which is seen most easily as elastic resistance.

3. Tones Pattern

This is not structural of course but functional. It is always present, however, and permanently changing. And since muscle tissue exerts pull on the fascial net, the ever-changing superimposed tonus pattern changes the pattern of tissue tension continuously, and so the spatial arrangement of the body in the gravity field also shifts constantly.(4)

The tonus pattern is determined and modulated by the nervous system. It is open to all kinds of influences from various sources. It often changes rapidly and drastically. The fascial net with its pattern of passive tension changes much more slowly and usually imperceptibly. Only in cases of accidents or an intentional intervention like Rolfing can it be seen to change noticeably in a short period of time. The gravity field is of course not subject to any change at all.

It should be emphasized that the concept of an underlying pattern of passive tissue tension to which the varying pattern of active tension adds is highly abstract.

In reality the two kinds of tension cannot be separated; only the total tension actually present at a given moment and with regard to a certain posture and activity of the muscular system can be assessed. Some idea about passive tissue tension is gained when the posture of the body is close to the Structural Point and muscle tension is low.

Mechanics of Motion

For determining the most economical form of a given movement among the large number of possible variations, three points will be observed with special attention. They almost appear self-evident but are nevertheless often disregarded.


Overall economy for the whole body is assessed. If e.g. a fairly economical way of lifting an arm is utilized but which disturbs the balance of the body which then takes a much larger amount of effort to be restored, this kind of movement is not considered economical. The principle of economy refers to the whole of the body just as integrity of structure always refers to the whole and not to local issues of organization. Translational movement of the whole body as expressed by acceleration and deceleration of its gravity center always involves noticeable effort and is therefore of primary concern.


Movements are analyzed in a circular form. From the initial state, a certain posture, the body or part of it goes into motion and then back again to the original posture. This condition excludes certain economical movements which are however not normal. Regular externals and locked-knee internals e.g. can lower their gravity center completely passively by sinking deeply into sleeve-supported stance. The normal form, Folding, requires a little effort for them initially because the pelvis must be shifted posterior to the Line first. But coming back up again from sleeve-supported stance takes clearly more effort than Unfolding.

This condition takes into account that it is not the isolated artificial movement which is important, but the overall sum of movements made throughout the day. And observing those movements soon reveals that there rarely exist truly still moments for a prolonged period of time.


The focus is on the initiation of a given movement. How a movement is begun determines largely its whole course. It is well known in physics that initial acceleration takes an inordinate amount of energy while reinforcing a motion already going on is much more economical. I often use as an example a car which has run out of gas and which must be pushed off the road. Getting it to move takes a lot of effort, but once it rolls it can be kept moving easily.

When the body holds a posture, is not moving, all the forces acting on it cancel out as stated by Newton’s First Law. The center of gravity and the point of support are on the same vertical line. If the body were non-deformable and “ideally rigid” in the physical sense it would be in equilibrium, although in the labile or unstable type. Since it is far from being “rigid”, the gravitational centers of all its segments would also have to be on the Line, and no rotation would have to be present. This is highly abstract and never exactly the case. Furthermore, even this more detailed condition presumes that the blocks are “ideally rigid”, which is of course not realistic. So gravity always causes at least some bending and shifting everywhere in the body. This induces strain in the fascial net as illustrated by the “blocks-in-the-elastic-sack” model (Rolf, p.33). This passive tissue tension serves to compensate partly for gravity’s destabilizing effect. It would help if fasciae were extremely tight and tense just as it is favorable to pull the shopping bag very tight around the boxes contained in it to stabilize the package (Feitis, p.72). The solution is not viable of course because such rigid fasciae inhibit movement which then would require a lot of effort.

With the fasciae resilient, the remaining tension necessary to prevent collapse comes from muscles. They tense the fascial net actively in the places necessary to counteract bending and shifting induced by gravity. This pattern of “base tension” of the muscular system depends on the posture chosen and on the individual structure, the properties of the fascial net of the person (Notes on S.I. 89/1, p.39).

To produce movement, this balance of all forces cancelling each other out must be disturbed. An imbalance results which by definition causes movement, “acceleration” of a part of the body or the whole body. From the point of view of the energy balance, the disturbance can be of one of two kinds. The tonus of some muscles can be raised and an imbalance and therefore movement results (flexion mode). Or the tonus of some muscles can be reduced, and movement results, too (extension mode). The two modes differ qualitatively. With the flexion mode more energy is spent compared to the initial posture. This is the dominant pattern. It corresponds to the general “knowledge” that movement takes effort, that movement is effected by muscles contracting. The extension mode saves energy in comparison to the posture held initially. Overall energy consumption is less. This is possible and seems to be true for any kind of movement although for many of them the phase of the initial gain is only momentary, perhaps only a fraction of a second, before muscle contraction sets in. Even then, overall effort for the whole movement is considerably less than with the flexion mode, for several reasons. The immediately relevant one is that muscles only reinforce a movement which has already begun but do not have to start it from zero.

So the question for movement in the extension mode is not which muscles need to “work”, i.e. contract, to effect it. It asks for the muscles whose tonus must be voluntarily reduced to effect an imbalance which causes the desired movement. They are generally on the opposite side of those which “work” in the flexion mode. Ida Rolf has stated this principle in the following way: “in flexion extensors extend when flexors flex” (Feitis, p. 158). Closer analysis suggests to reformulate it more precisely as: “before flexors flex, extensors extend”. It should be noted that in these statements the terms “flexors” and “extensors” are used in a broad sense. Restricting them to their anatomical meaning would mean for one that only flexion is covered but not extension, adduction/abduction , rotation , pronation and supination. So “flexion” is interpreted to mean movement to that side where the angle between the two parts moving with respect to each other, at the rotational axis, closes or becomes smaller. The antagonists in any kind of movement are then the “extensors”. And “extensors extending” does not mean that these antagonists “work” but that they become longer, that they lengthen functionally. In “traditional language” the principle would be stated as “antagonists relax before agonists contract”.

It is typical and perhaps only possible because of the specific point of view of the field which regards the body in the gravity field and not by itself that it is never the musculature which by contraction initiates movement. The forces which cause movement are as follows:

1. Gravity

Initial tonus reduction of some muscles disturbs the equilibrium of posture. Gravity is not fully compensated anymore and so causes some sinking, which is acceleration toward the ground, somewhere. A simple illustration is given by walking. The most obvious although not most difficult feature is that the leg which is behind is brought forward. Physically, this leg forms a pendulum which is held back. When the weight of the body is fully on the leg in front, and when all muscles in front and in back from the thorax on down to the foot relax, the leg swings forward. The movement is entirely passive, effected by gravity alone, and actually a little energy is saved by it, at least as far as this side is concerned. If the swinging leg is not inhibited by muscle tonus or rigid fasciae it will carry way forward, well beyond the point where the leg is vertical below the upper body. The exact description is more complicated however because “the leg”, the side which swings, is something like a four-part pendulum. Its members are the pelvis, or more exactly: that half of it which belongs to the swinging leg, the thigh, the lower leg, and the foot. It is the knee which swings or leads the movement. This means that if the focus is on the knee, as if it were heavy, and if it is sensed to swing straight forward passively, the movement is optimized in the easiest way. Lower leg and foot are imagined to be suspended from it and be dragged along passively, staying behind the knee first because of their inertia.

2. Elastic Force

Muscle relaxation also causes an imbalance in passive tissue tension so that the elastic energy stored in the fasciae is set free. For the hip joint and again in the example of the leg that swings in walking, there is a higher tension in the flexor tissue than in the extensor tissue. With the leg behind and the upper body forward that hip is extended or even slightly hyperextended. The tension in the flexor side flexes the hip, i.e. exerts a forward pull on the thigh. The elastic force acts here in unison and synchrony with gravity. It is also “for free”, it doesn’t cost any effort just like gravity. It also becomes active under the condition of initial tonus reduction and by this condition also saves energy.

3. Musculature

Only the third source of forces costs energy. In normal walking, as in some other forms of movement, it is not employed at all, the first two forces of gravity and elastic force doing the whole job. If muscles are called upon, they always exclusively reinforce the movement started already by the two passive forces.

It should not be too much of a surprise that in the field of Structural Integration the “prime mover” is not a muscle but gravity.

Features of the Extension Mode

The extension mode of movement constitutes normal function while the flexion mode does not. Three criteria offer themselves which permit to distinguish the two modes sharply because they are separated by qualitative differences.

How to create a Banana

The figure of Fig.1 can be thought to represent a longish children’s balloon. The length of the midline is given by the equation m = a+p/2. In bending this is still true approximately. The balloon can be bent in two different ways. One side can be pulled together with the fingers of the two hands. This corresponds to a unilateral contraction of the muscles parallel to the long axis of the body on one side. This side will shorten functionally with its tension increased. The imbalance in the degree of tension of the opposite sides will cause the balloon to bend. The concave side will be shorter, the convex side will be bent but not longer. Therefore the midline will also be shorter than before.

<img src=’https://novo.pedroprado.com.br/imgs/1991/1040-1.jpg’>
Fig.1 “Creating a banana” in a children’s balloon. In the flexion mode the midline shortens, in the extension mode it lengthens.

In the model of the air-filled balloon pressure will rise inside and so the convex side will actually be a little distended. But its “lengthening” will definitively be less than the shortening of the concave side.

In the extension mode one side of the balloon is pulled apart. The balloon will also bend but this time the convex side is longer than it was before, the concave side not (noticeably) shorter. As a result the midline is longer than it was before. This corresponds to a tonus reduction or relaxation of the muscles on the convex side of the body functionally. The structural equivalent would be a softening or making resilient of the fasciae of this side.

The midline never stays at exactly the same length in movement if one looks closely enough. If it lengthens initially, function is normal; if it shortens, it is not. The observation is a direct consequence of separating extension and flexion mode. In the first the overall muscle tension acting in the direction of the long axis of the body is diminished; the body extends(5). In the second, it is increased; the body is shortened.

Energy Expenditure or Saving

Fig.2 shows a client lifting an arm in the flexion and extension mode. In the flexion mode, the shoulder is pulled up and medial. The trapezius contracts. Often the whole shoulder girdle is lifted on this side with the levator scapulae, the rhomboids, and even the sternocleidomastoideus active. The arm is then lifted by contracting the deltoideus and the supraspinatus, and frequently the triceps and the biceps and coracobrachialis “help” by contracting in synchrony. The forearm is also pulled up and onto the humerus by muscle contraction. A lot of energy is spent in the axial direction of the arm to pull the arm onto the trunk and “jam the joints”. This raises the resistance which the muscles which produce the desired effect have to overcome first before they actually lift weight.

<img src=’https://novo.pedroprado.com.br/imgs/1991/1040-2.jpg’>
Fig.2 – Model lifting an arm in flexion (left) and extension mode (right). Note balance and imbalance at the level of the ischia.

Fig.3 is a schematic representation of the energy expense involved. From a basic level of energy which sitting takes in the example chosen, the curve showing the additional force necessary rises steeply and far. With the arm moving up this decreases a little and comes to a plateau which is higher than the basic level indicating that the arm is held up now.

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Fig.3 – Energy expense per time unit for lifting an arm in flexion (left) and extension mode (right). The horizontal is the base line and indicates energy consumption for the initial posture, e.g. sitting. The shaded area under the curve gives the total additional energy necessary for the whole movement.

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In the extension mode the area under the base line must be subtracted. Energy consumption is less in the extension mode. Initially energy is saved instead of spent. The arrows indicate the phases of the arm moving up, the arm being held up, and the arm moving down.

For taking the arm back down again the muscular view will name the muscles which by contraction effect this movement. Here the situation is so obvious however that one or the other might at last get the idea to let gravity do the job.

In normal function, the extension mode, the focus is on the elbow which leads the movement as stated by Ida Rolf. First the elbow is sensed to become heavy. If this is successful it means that all the muscles binding the shoulder girdle to the trunk have reduced their tonus. It is sometimes necessary to do that with the shoulder first and separately. Then the shoulder sinks and the elbow also sinks slightly, at the same time beginning to swing out to the side passively. Subjectively the elbow is then simply allowed to continue the movement. The situation is optimal if one can have the impression that the elbow will swing out and go up all the way by itself unless the movement is stopped actively by intention. The forearm seems to be carried along passively. After the movement has begun it is best to attend to the shoulder which should be sensed to hang low and far out. If one reaches high up the shoulder should be imagined to stay far lateral and being pulled up passively by the elbow rising.

The arm comes down passively, of course, by gravity alone. Muscles can be imagined to have a somewhat lower tonus than in the ground state, so a little energy is saved again.

The overall energy necessary to perform the circular movement is given by the shaded area in the graph. For the whole movement the difference is quantitative. Flexion mode takes more, extension mode less energy. But for the initiation of the movement there is a qualitative difference which sharply divides the two modes. The Legion mode takes more energy than the previous posture; in the extension mode some energy is saved at first.

The difference can be felt most clearly if the “mildest” form of the flexion mode is compared with the extension mode. One concentrates on the deltoideus which is used solely to begin lifting the arm by contracting. One will find that it is difficult to not also raise the shoulder. But even if successful, one will notice a clear axial thrust initially, which jams the shoulder joint first, however softly the movement is performed. In contrast to this, in the extension mode the arm hangs out of the shoulder joint more first, and intraarticular pressure as well as tissue resistance is reduced.

Enhanced or Distasted Balance

The considerations concerning energy expenditure have been made under the assumption that tonus in the musculature of the rest of the body remain constant. If sitting is normal (cf. Notes on S.I. 90/1), tonus reduction is not confined to the muscles of the shoulder girdle but is best as general as possible. This leads initially to a very slight sinking; the body settles a little more down on the bench. Since equilibrium is of the stable type no reaction is needed. With some experience one is able to sense that initially the pelvic floor flattens a little on the bench and is pressed more against it. Balance improves momentarily.

As soon as the arm starts to go up, is accelerated upwards, the rest of the body is propelled down by an equal force according to Newton’s third law. One is a little “heavier” for a moment just as one’s feet are pressed more against the floor of an elevator which starts to go up. Balance is so further improved during the acceleration phase.

With the flexion mode one senses first that the upper back is pushed to the other side. The space between the shoulder blades is jammed. In the extension mode the upper back “opens” in contrast. If attention is directed to the ischia one senses that the weight of the body is lifted off the side of the arm moving up and thrown over to the other side. Balance is disturbed. To restore balance or, what is more often the case, refraining balance from being disturbed too much takes a considerable amount of effort which costs energy “unnecessarily”. This energy expenditure must be added to the curve of FIG.3 and renders the quantitative difference in the effort necessary for the whole movement rather impressive.

With posterior tilt sitting, which is not normal, the difference is only quantitative. Balance is always disturbed, more in the flexion mode, less in the extension mode.

Summing up, three criteria have been found which separate flexion and extension mode sharply. They are immensely useful in the practice because with some experience they can be sensed very clearly in one’s own body and observed in clients’ bodies with great precision.

1. Economy

This criterion is a direct reflection of the basic premise not only of the field of Structural Integration but concerning all fields dealing with structure and function. The qualitative difference is found at the initiation of movement where either energy is spent or saved.

2. Midline

This appears as something like the structural criterion specific to the field. The midline either shortens or lengthens initially.

3. Balance

This is properly the specific functional criterion. Balance is either disturbed or improved initially.

All three criteria are a direct consequence of the extension mode where “extensors extend before flexors flex”. Initial reduction of muscle tonus is the condition for gravity acting positively and producing movement. It is at the same time sufficient because gravity will always come into play by it. That it be productive instead of destructive depends solely on the conditions chosen at the outset.

Hinge Theory

Hinges have been defined as rotational axes in a body which conform to three criteria (Notes on S.I. 88/1). Reference is to the same criteria if the expression is used that rotational axes, or less exactly “joints”, possess “hinge function”. These criteria also permit to distinguish sharply between normal function and function which is not because the two are divided by a qualitative difference. Hinge function results directly from and is produced by the extension mode. Hinge considerations are, in the field of Structural Integration, the equivalent to what “joint theory” is in other fields. Typically, “hinge” is a more abstract concept than “joints” and of course places the issue in a completely different context.

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<img src=’https://novo.pedroprado.com.br/imgs/1991/1040-6.jpg’>
Fig.4 – Head extension in the flexion (left) and extension mode (right) in the front and in the side view.

1. The axis of rotation initially goes toward normal and back in a circular movement instead of away from normal and back.

This first criterion goes from the stipulation that in a normal structure in neutral stance all axes of rotation are exactly in one of the three dimensions of space. The matter is easily exemplified by the axes of the hip joint with its three degrees of freedom. The axis for flexion/ extension should be exactly transverse, that for rotation vertical, and that for adduction/abduction sagittal. First, it is obvious that the concept is again highly idealized and abstract and one may hesitate to ascribe any significance to it. However, application to practical problems – which has not been developed very far yet – has shown that it is immensely productive and clarifies seemingly very complicated questions in an amazingly simple way. Even in most exotic and contorted postures from which movement is to be initiated, referring to the three dimensions of the body usually makes it easy to decide in which direction the rotational axis has to go to constitute normal function(6).

Nothing ever conforms exactly to the ideal. Observation of the direction which the rotational axis takes initially – toward or away from normal – allows to determine reliably whether the respective movement is normal or not. FIG.4 shows “head extension” in flexion and extension mode. The rotational axis should be exactly transverse and go through the gravity center of the head segment. It can be thought to go through the ears. In the model it is lower on the left, higher on the right. Displacement in the horizontal plane cannot be seen well in the frontal view.

In the flexion mode the sideward slant of the rotational axis increases, in the extension mode it decreases. Flexion mode is produced by asking the client to focus on the muscles of her nape and to pull down the back of her head, the occiput, by contracting them. The extension mode is a little more difficult to evoke. The client is asked first to sense the whole back from the head down and the whole front as relaxed as possible without changing the bodily arrangement. Then she should relax the front from jaw to pubes additionally. It is favorable to focus on the pubes first which should be felt to sink a little. Then, because of the longitudinal tension in front decreasing, she should imagine that her face begins to float straight up. She should then simply allow this movement to continue all by itself. This is sometimes too subtle for some clients. They can be asked to contract back and front vigorously first. Then by selectively reducing muscle tension in front they usually succeed in attaining extension mode. The difference is felt very distinctly in normal sitting. But also in posterior tilt sitting and all kinds of standing, except for sleeve-supported stance, it is still clear if tonus reduction is very specific.

2. The axis of rotation initially goes away from the center of the body instead of towards it.

This criterion is a direct consequence of the extension mode, too. It can be experienced easily in the following way. In sitting or standing the head is pulled down on the body without raising the shoulders. All the muscles running from the trunk to the head are contracted concentrically and forcefully. The downward movement of the head comes to a halt when it is jammed down on the trunk and the resistance of the compressed material body equals exactly the downward pull of the “working” muscles. Gravity and normal force nearly cancel each other out and can be disregarded here.

Equilibrium is described by the two force vectors of the same length both acting in the vertical dimension but in opposite directions. The downward force of the muscles – on top of passive tissue tension – is cancelled by an elastic force resulting from the resistance of the material of the body. It acts to push the head up. When muscles are relaxed concentrically an imbalance is generated. The elastic force pushing up is momentarily greater than the downward pull of the muscles. As a consequence, the head is accelerated upwards. Of course, the elastic energy set free this way and which was contained in the compressed “spring” of the trunk diminishes quickly. The upward movement of the head soon stops.

This “experiment” is instructive for the point of view of Structural Integration which looks at the whole body as a physical entity in the three-dimensional field erected around gravity and normal force. If the upward movement of the head is observed in isolation it would easily seem to violate the laws of thermodynamics and physiology. No object heavier than air can move upward all by itself in the gravity field! One would then look for muscles which by “working” pull up the head. But of course none of these can be found; there exists no “skyhook”. Finally, highly sophisticated reflections will be undertaken to show how the “intrinsic muscles” of the neck by contracting manage to straighten out the cervical spine and so push up the head(7).

The “naive” conventional view implicitly regards posture as a “static state” where nothing is happening. Relaxed muscles are “doing nothing”, they spring into action only when they contract. In contrast, the physical view of the body in the gravity field understands posture as a “dynamic state” where all the relevant forces just cancel out. The logical conclusion of what must happen so that movement results is then not that muscles must contract but that an imbalance must created. In the extension mode, and in any movement initially, this is by muscles reducing their tonus, not by contracting. The apparent paradox that the head goes up when muscles relax so turns out to be just a straight application of simple mechanics. It promises to perhaps explain the phenomenon of “lift” eventually. It would be effected by the normal force of the earth and elastic forces in the body, which are of the same kind; it would be initiated by tonus reduction of the musculature which means “giving in” to gravity locally or in a general way; and it would depend on certain geometrical conditions necessary at the outset.

3. The axis of rotation initially aligns better with the other axes instead of worse.

This third criterion was originally developed to describe the nature of the thoracic spine extending with the transverse axes of rotation between the vertebrae in mind. In the example of the head extending and in neutral stance, the rotational axis should be on the Line, as should others, specifically that of the shoulder, the hip, the knee, and the ankle. In reality it is never exactly on the Line. But it should of course go toward the Line and not away from it, aligning better with the other axes which should be on it. With most people it is in front of the Line and so should go back initially. In the rare cases of a posterior head segment it would go forward first.

The criterion would thus be identical with a stipulation that the midline through the body should straighten out initially, just as the second criterion is an expression of the general formulation of the midline lengthening instead of shortening.

Head extension also exemplifies the second and third criterion. With the initial reduction of tension in the front from head to pubes the face rises while the back of the head does not sink. So any point between front and back of the head also rises, the more forward the higher. The axis of rotation as well as the gravity center of the head go up initially, away from the center of the body.

As can be seen in FIG.4 the head which is structurally anterior also goes back as well as up. Tension in the front of the trunk not only pulls the head down but also forward. This is especially marked in the head because the frontal part of the sleeve not only attaches to its front but also branches out to the back via the fascia of the sternocleidomastoideus and the scalenes.

Head extension is exceptionally apt to demonstrate the structural point of view because the axis of rotation is far away from the joint to which it belongs. It is rather unfortunate that often the axis of rotation passes more or less through its joint which easily leads to a confusion of the two concepts. The atlanto-occipital junction is in other fields the focus of attention. It does not even play a role in the field of Structural Integration beyond the fact that it does permit “head extension”. In the practice, the behaviour of the axis of rotation will be observed. From the functional limitations and restrictions which disturb or prevent optimal hinge function, one will try to diagnose the parts of the fascial net which, because of their shortness, are most responsible for them. When this has been relieved, function will have been improved and one can positively state that the structure has been integrated somewhat, all other things remaining equal. Of course, if one goes for perfection one will eventually reach limitations presented by the joint itself (ossary factor). But it is generally undesirable and usually senseless to go that far. As soon as one has got some improvement one will leave the area and focus on organizing the large rest of the body to match the gain in structural integrity one has made originally.

The fact that the rotational axes behave according to these criteria in the extension mode needs explanation. The larger part of the effect of the musculature is in the longitudinal direction. Muscles act more parallel to the long axis of the body, less so transversally and sagittally. By so tensing the fascial net they jam and shorten the body. Rotations, tilts, and bending become more marked. When tension decreases the body lengthens and aligns better in the vertical dimension. A bedspring serves well as an example. When one tries to compress it straight down from above one will not succeed. Very soon the spring “escapes” sideways, it bends out and contorts. When one releases pressure slowly it will extend and straighten out to approach its symmetrial cylindrical shape again. It can be imagined that the spring, instead of being pushed down, is tied down with various strings which are tightened more and more. The same picture of bending out and contortion will result. The strings represent the fasciae, tightening them more and more imitates muscle action.

This model of the body as a spring tied down asymmetrically by strings on the outside generally works well with hypertone bodies and overcompensated structures. It works less well when they are collapsed. With them, all depends on the posture which must provide “sufficient” support. What “sufficient” means is not completely clear. But Sitting (Notes on S.I. 90/1) provides an example which does not depend on the structural type. When sitting is normal, all bodies conform to the “tied-downspring” model regardless of whether their structures are collapsed or overcompensated. When it is not (posterior tilt sitting), every body will sink with general muscle relaxation and nothing will go up.

The objection can be raised that the extension mode is not possible for movements which rise up from a posture where only base tension is present, i.e. the absolute minimum of active muscle tension which is necessary to maintain the posture. This is probably true. But the fact seems to be that this is never the case. Postures always appear to contain at least some excess tension. Usually there is a considerable amount of it. Excess tension always “ties down the strings” while base tension secures the posture from collapse.

A further objection can be made by a rather sophisticated conjecture. A body is assumed to stand with base tension and some excess tension which is used to keep all axes better aligned than they would otherwise be. The posture would correspond to a place on the Postural Curve, a little away from the Structural Point in the direction of neutral stance. The crucial point is that the objection implies that the body is exactly on the Postural Curve or only slightly above it. This seems to be rarely the case at best.

So the two objections, that of the collapsed structure with hypotone musculature and the ingeniously improved posture must be kept in mind.

Movement in three Dimensions

Movement of the whole body can be examined in three dimensions. That of legs, arms, and head can be analyzed similarly. Movement in the sagittal and transverse planes also involves movement along the long axis of the body, up and down, that around the vertical axis does not.


Folding is normal movement in the sagittal dimension but serves mainly for the body to go down and up (Notes on S.I. 87/1). The parts of the body “escape” equally to the front and the back which permits the center of gravity to descend straight down without useless horizontal displacement. The folds which go back are the hips, i.e. the transverse axis through the centers of both hip joints, and the ankles. Those going forward are the knees and the shoulders. The shoulders are a convenient substitute for the more exact “cervico-thoracic junction” used earlier and termed a “semi-fold”, just like the ankles.

Folding resembles the closing of a map. If all the folds are on the right side, it will close easily by just pushing together the cover leafs. If one or several folds are on the wrong side there will be resistance and a jamming up of the map. Using force cannot be recommended but is necessary if one insists on closing it this way. Similarly, the body will not fold down easily if the folds are on the wrong side. It will especially take a lot of effort to come back up again.

Folding is very rarely done spontaneously. One reason is probably the fact that most people use a stance with a functional anterior pelvic shift, at least when they are set to stand for a while. The other folds then also tend to go to the wrong side of the Line. The shoulders are back, the knees are hyperextended where possible. With general tonus reduction some folds will go in the wrong direction. Certainly the pelvis will sink forward, the upper body back down. Perhaps this “average stance” with the folds on the wrong side is chosen so persistently because of the physical advantage of “stiffening” the folds. They so provide some protection against being “folded down” by gravity. The “neurological advantage” must not be underestimated, however. It is probably even more important. Average stance can be monitored and regulated with much less expense to the nervous system than “normal standing”.

“Normal standing” is in minimal Folding. One may visualize it as standing nearly straight with the folds just one millimeter on the right side of the Line. The structural norm for standing contains among other things the condition that ankle, knee, hip, and shoulder be precisely on one vertical line. This is never the case exactly. The functional point of view examines and compares the two possible directions of deviation. With a few exceptions of what could be called “mixed folds” there are two patterns of deviation. One is Folding where the folds are on the right side. This is rare in reality and is usually seen only in a few regular internals who are not able to bring the folds easily across the Line to the wrong side. The other is “average stance” with the folds on the wrong side. It is by far the most frequent pattern of standing. However, “minimal Folding” must be considered normal function mainly because as the starting point it allows to perform almost any kind of movement in the most economical way, i.e. “normally”. As soon as one goes into movement of virtually any kind out of “average stance”, the possible economical advantage evaporates quickly, and “average stance” turns into a handicap. If one just waves good-bye, does the dishes, or turns the head to look sideways, the energy expense for the whole body exceeds that which is necessary in “normal standing”.

It would of course be utterly senseless to demand for anybody to stand “normally”, or to use normal function in general. There is absolutely no moral or ethical value involved with normal function just as there should not be placed any sense of obligation on anybody to have structure “normalized”. Normal function and normal structure are a fascinating preoccupation for a small minority For the large majority they often present a powerful means to promote what for Structural Integration are side-benefits and which concern health, well-being, aesthetics, etc. But many people and most clients profit immensely if they are shown the mechanics of normal function, including “normal standing”. The easiest way to demonstrate this is when they have learned Folding. When Unfolding slowly they will notice that the folds are dragged more and more toward the Line in extension against the ground. They are then asked to notice the instant when the folds slip over to the other side of the Line to attain “average standing” and especially to sense how they are losing height and balance. They are then also able to experience the switch in direction in which gravity pushes out the folds.

Some difficulties that clients encounter regularly with Folding need to be addressed. At first, the pelvis is almost never left to swing back freely; it is held close to the Line and almost always tilts posteriorly. It helps sometimes to explain how gravity affects the body and causes it to collapse. This is very different to the way we experience falling. It is more like slipping on thin ice. Visualizing this, one will realize the seemingly strange fact that the legs are catapulted away from under one’s upper body which appears to drop straight down, and very rapidly at that. For the pelvis, this can be experienced by imitating the one-joint model and letting the body jack-knife. The pelvis will shoot backwards with extreme acceleration, tilting anteriorly, and the upper body will fall not so much forward as down.

The pelvis behaves physically like a bowl suspended from the thorax in front and in backs. With general tonus reduction it will sink down and away from the thorax a little. It will also tilt anteriorly – the pubes “swing back between the legs” – because longitudinal expansion is much more marked in the anterior wall of the trunk than in the posterior one, the back, for anatomical reasons. The resistance from the legs and femora comes from below and anterior, and so the pelvis shoots straight back. The feeling should not be one of the pelvis dropping down, except for the slight initial sinking, but of it being flung back horizontally.

The structural norm for the trunk states that its midline should be straight. Functional considerations will again examine the direction of deviation. They are decidely asymmetrical. It turns out that energetically it is favorable if the midline through the trunk from pelvic floor to cervico-thoracic junction is anterior convex. It should never be posterior convex as a whole or in any part. The principle can also be stated in a different forms namely that the structural norm of the midline – straight – should always be approached from the anterior convex deviation, never from the posterior convex one (cf. Notes on S.I. 90/1, p.22).

The “one-jointed” Folding shown in Fig.5 is best initiated in the following way. Tonus reduction in the chest and abdominal wall lets the pelvis begin to go back. At the same time it starts to tilt anteriorly. Head and upper thorax should stay up and not sink. One can imagine that they stay there as if suspended for a moment by their “inertia”. The weight of the pelvis moving back and tilting anteriorly swiftly pulls the front contour of the trunk very long. But also the back is pulled long, although less than the front, if its musculature is relaxed. This means that the midline through the trunk lengthens maximally. From geometrical considerations it is also evident that the midline through the whole body must have lengthened. It bends out more in the posterior direction at the level of the pelvis but still reaches up to the same height(9).

<img src=’https://novo.pedroprado.com.br/imgs/1991/1040-7.jpg’>
Fig.5 – “One-jointed” Folding. The pelvis swings back first. Only the hip joint flexes, all joints above extend. At a certain point the hips can’t flex more and the concave curve of the lower back becomes convex; the lumbar spine hyperextends (3).

<img src=’https://novo.pedroprado.com.br/imgs/1991/1040-8.jpg’>
Still farther into the movement, the thoracic spine can’t extend more and even begins to flex (4). Coming back up begins with letting the pelvis go back maximally into the extensor sling of the hips (5). Extension of the back is reestablished before the hips start to extend (6).

The posterior wall of the trunk lengthens and becomes flatter, indicating that the spine extends over its whole lengthen(10). The sacrum is in maximal extension with regard to the ilia, too. This expresses the principle that in Folding it is solely the hip joints that flex while all other joints, specifically in the spine, extend. Exactly the opposite is usually found: There is little flexion in the hip joints but a lot in the spine.

In nearly all kinds of movement the spine can and should extend initially. In Fig.5 it stays extended as long as possible. The crucial points to watch below are the iliac crests. They should sink downward “into the body” and back away, always more so than the lumbosacral junction, to effect a passive lengthening and extension of the lower spine. The cristae should never push out of the back posteriorly. This depends of course entirely on maximal relaxation of the abdominal wall(11).

At a certain point the capacity for flexing the hips and extending the spine is exhausted. This point varies greatly with different people and can almost be taken as an indicator for structural integrity, or its lack. The hips can’t bend much farther, and when continuing the movement the iliac crests stay back. The lumbar spine will go into hyperextension.

The crucial place to watch higher up is the dorsal hinge (Notes on S.I. 88/1, p.32). It should also extend but frequently bends. There is also a point in the course of the extreme movement shown when it begins to flex. It is then important not to aggravate this: the sternum is sensed to hang down and slightly forward, the pubes must stay back and up.

Coming back up normally is highly sophisticated and can hardly be found spontaneously. As usual, one begins by sensing clearly the feet being pressed flat against the ground by the weight of the body. Then one focuses on the pelvis being pushed back up into the tensed fasciae of the hip extensors by gravity. It is generally favorable if one uses “extension against the floor” to sense this clearly, pushing the hip actively back up into the extensor sling a little more. Now the anterior convex midline of the trunk and extension of the spine at the lumbosacral junction and the dorsal hinge is regained first. The sternum is imagined to slide forward approaching horizontal. Care must be taken that the pubes don’t come forward with it. The passively tensed extensor sling of the hip joints is used as a sort of buttress, the pelvis being pushed even more back into it while the chest with the sternum goes forward. With the anterior convex midline through the trunk and full extension of the spine established, the movement of coming up, Unfolding, is now reduced to an isolated extension of the hips. It is effected largely by the elastic force stored in the extensor fasciae of the hip with minimal help by the muscles. In coming up, the upper back must by all means precede the iliac crests which should stay down to sink forward into the body. Of course, the front of the body from pubes to chin must stay completely relaxed, the scapulae should hang down laterally(12).


The midline of the body as seen from front or back is assumed to be straight and vertical in standing. Gravity is then neutralized by the Normal force of the earth. Longitudinal tension on the left and right side of the body is equal although it may be composed somewhat differently of passive and active tension. The problem is now “how to create a banana”. In the extension mode, tonus is reduced on that side which is to become convex. One imagines the leg of that side becoming heavy, the weight settling fully on the floor.

The imbalance in tension created this way will cause the body to bend. It is again not the upper body which goes down on one side primarily, but the pelvis going out to the other side. Firstly by tensional imbalance, but superseded almost immediately by gravity, it is pushed away laterally and into the sleeve. Only then does the upper body sink to the other, concave side. The convex side lengthens a little, the concave side is not shorter initially. This means that the midline has lengthened a little.

The focus is on the pelvis at about the level of the iliac crests, at the height of the gravity center of the whole body. The more it is left to push out into the sleeve, the more passive tension will be built up in it which helps to maintain the posture and is later used to bring the pelvis back into line again. Throughout the movement a sense of the weight of the leg on the convex side being down on the floor must be preserved. In flexion mode, where muscles on the concave side contract, this leg is lifted off the ground.


This is the most difficult kind of movement because gravity does not come into play directly. It is effected solely by tensional means.

The elastic sack which unsheathes the body is imagined to be made up of fibers which run diagonally from the left leg to the right shoulder, the right leg to the left shoulder. Of course they encircle the body and are present in back as well as in front. Their exact orientation can be thought to be varied, e.g. from the left leg to the right hip, depending on the movement which is under examination.

Anatomy knows muscles which act in such an oblique direction. Structurally, the collagen fibers of the fasciae are primarily important. They carry passive tension and are in addition tensed actively more or less by muscles.

When standing still, the total tension of the fascial fibers which run obliquely and cross to each other is equal. In the extension mode, a tensional imbalance is created by selective tonus reduction. If the body is to rotate negatively, clockwise, one senses the weight coming down the left leg more strongly. The fascial fibers running from the left foot to the right shoulder across the front of the body lose tension, and the right shoulder will begin to drift back. The left shoulder will begin to come forward as a consequence. It is generally preferable to produce the moving back of some part of the body first and sense it clearly because “back” is the “forgotten dimension” in our consciousness.

However, gravity does not set a preference of direction as in rotation around the horizontal axes, and front and back are not asymmetrical or distinguished in any way in a physical sense. The same movement, negative rotation, can also be produced by sensing the weight down the right leg and reducing tonus which acts along the diagonal from right foot to left shoulder, across the back, of the body. The left shoulder will begin to drift forward while the right one follows by receding back.

Rotation becomes stronger and faster when it is helped actively. After its passive initiation, when one feels the weight of the body pressing the foot flat against the ground, extension against the ground is added to speed up the movement. One senses the resistance of the ground pushing up diagonally to the shoulder of the other side. In general, all movement, which in physics is called acceleration, must be sensed as if coming out of the ground if it is upward. The push from down below the foot should be felt along an uninterrupted line up to the leading part of the movement. The feeling is clearest if standing is normal and if all parts not involved, especially the sleeve, are maximally relaxed by sensing them as heavy.

Standing on one leg only and in a distinct Folding posture magnifies the sensations mentioned. One’s body goes easily into rotation in either direction by just imagining the oblique line through the body relaxing and the leading part drifting away from the foot.

So the general principle for rotation is to let the body settle more on the ground without the center of gravity sinking, sensing the appropriate oblique line of tension in the body relaxing, and then reenforcing the movement backwards started this way by extension against the ground. Clients usually then notice that this way the body really rotates around a nearly vertical axis which remains unchanged, half of the body going back, the other half forward.

Some Physical and Physiological Annotations

The justified objection has been raised(13) – concerning Folding – that from the point of view of gravity it would be logical to hold the parts moving out as close to the Line as possible and not let them hang out all the way. The first answer to this is suggested by the wording, which has been chosen intentionally, of course. It is more economical to let something hang away then holding it!

The argument deserves a closer look, however. The answer is sufficient for stances down into Folding, but it is not necessarily so for movement down and up, especially if it is quick. For, the farther e.g. the pelvic segment is left to go back, the more energy is necessary to bring it forward to the Line again in Unfolding.

The subjetive experience when comparing Unfolding with coming up from “average bending” shows without a doubt that Folding is preferable. An objective description can be given which explains this. The body in standing possesses a certain amount of potential or gravitational energy. It is proportional to the height above ground of the center of gravity. In bending of any kind, the gravity center sinks. Some potential energy is lost. In “average bending” it dissipates as heat. To come back up from “average bending” requires that the amount of potential energy lost be put into the system, the body, again. Muscles do the job by using chemical energy which is that kind of energy which is meant by “energy expenditure”.

In Folding, only part of the potential energy is lost. Another, sizable part is converted into elastic energy. It is contained in the stretched fasciae and manifests as (passive) tension. It is turned into potential energy again in Unfolding and so reduces the amount of chemical energy necessary. Conditions are optimized when in going down, one imagines and senses the weight of pelvis and knees distending the extensor slings maximally. They can be visualized as strong elastic bands.

Before coming up, this sensing of the weight pushing out in back and in front is recalled as vividly as possible. Then one focuses on how the whole weight of the body flattens the feet against the ground. Intensifying this sensation, it is easy to imagine that the body begins to straighten up passively, as if propelled up by the tensed elastic bands around the convex contours of the body. It is important never to lose contact to the ground, to sense an uninterrupted line through the body up to the top of the head which extends, or “is extended”. Imagining and sensing the physical forces in the body is an accurate tool for optimizing the tonus pattern. It eliminates active tension where it is unnecessary and inhibits the passive process.

The physics of Folding and “average bending” can be exemplified by a simple image. If one jumps from a wall and then climbs back up again, the job is made very much easier if one places a spring board underneath.

The capacity of fasciae to store elastic energy depends on their resiliency. Thickened, rigid fasciae have lost part of this capacity. They can be compared to an old, hardened rubber band which is brittle in some places. But also fasciae which are too soft have lost some of this capacity. They can be stretched too far too easily. Fasciae can be said to be optimally resilient when they “recycle” gravity best, i.e. when they convert a maximum of the potential energy lost in going down into elastic energy, which is then utilized fully for bringing the body back up again.

This mechanism also emphasizes the importance of the midline lengthening maximally. For, the longer the midline gets, the more elastic energy will be taken up by fascia on the convex side of bending. This can clearly be felt in sidebending. The more one succeeds in letting the foot settle on the ground by tonus reduction before the pelvis is pushed sideways, the more the shoulder rises up passively, and the easier the coming back to vertical will be.

Muscles in their capacity for contracting have so far only appeared as an undesirable and disturbing factor. A reason for this is that in the practice of experimenting with the extension mode and evoking normal function, that is exactly what they are: a source of disturbance. Subjectively, they disappear as defined entities in normal function; one feels weight, tension, and pressure, and their quantitative and qualitative changes. Sensing the pattern of physical forces and its change seems to cause the perception of anatomical characteristics to vanish. But also purely theoretically, it appears increasingly doubtful that the concept of “working muscles” is of any use in the structural context. Structural Integration is more akin to applied physics, less to applied anatomy.

Muscles by contracting never initiate movement if function is to be normal. This is done by the gravitational and elastic forces. The condition that these “passive” forces become active is actually that muscles contract less, reduce their tonus. Muscle activity only reinforces a movement already begun if necessary or desired.

Musculature is divided in established fields in various forms, e.g. into “red” and “white”, “postural” and “functional” muscles, or “slow-twitch” and “fast-twitch” fibers are discerned. For our purposes it makes sense to distinguish “deep” muscles from “superficial” ones, although an exact boundary between the two cannot be given^l4. The “deep” muscles are closer to the midline of the body and the limbs, but they are also shorter in range, with the psoas as a notable exception(15).

Muscular reinforcement of a motion of a part of the body should be from inside to outside. The “deep” muscles first add to the acceleration, only then the bulkier and stronger “superficial” muscles come into play to produce “end-speed”. One reason is that “deep” muscles are shorter in range and usually cross only one joint. Muscles which cross two or more joints are tendentially disruptive to the configuration of the body and should be used last. But “deep” muscles generally have a better angle of leverage for the desired action, too. “Superficial” muscles tend to waste a lot of their power. The hamstrings flexing the extended knee by contraction present a vivid example.

A third reason is the peripheral positioning of the “superficial” muscles. This gives them a great leverage for compressing the center of the body. And this again leads to a fourth disadvantage. For, premature contraction of the “superficial” muscles shuts out the “deep” ones; they don’t have the “space” they need to contribute to the action.

Initial tonus reduction is the “sine qua non” of normal function. It especially concerns the “superficial” muscles. The body distends because of it, its parts are “pushed apart” a little by the elastic energy set free in the material of the body. This lengthens, or “pulls apart”, the “deep” muscles. They get the prestretch they need to work efficiently. Tonus reduction of “superficial” muscles then possesses a double benefit. Physically, the fasciae are “loaded” with elastic energy; physiologically, conditions are optimized for the “deep” muscles.

Lifting the lower leg in sitting as an example may help to clarify the issue and the problems surrounding it. Sitting should be normal. It is safer and more convenient to be forward with the upper body, even supported by the elbows on the table, in what has been called “standard movement” (Notes on S.I. 90/1, p.20).

The movement is initiated by reducing the tension on the posterior side of the leg. Specifically the tonus of hamstrings and gastrocnemius is reduced. This induces a slight sliding back of the ischial tuberosities which in turn produces a further slight extension of the trunk of the body. The foot begins to slide forward. It stays as low as possible and the sole of the foot keeps its horizontal orientation. The tibia is sensed to detach a little from the femur, and it stays back maximally, posterior to the femur. The weight of the lower leg and the foot is imagined to pull the leg long. Leg and foot go straight forward first. They only beging to also go up when there is no alternative but to do so, in order to go forward more. The rectus femoris then feels relatively soft on palpation. It does not “work”. But also the accessible outer layers of the vasti are not contracted and hard. The tissue feels as if “tensed a little”, rather than contracted.

All this suggests to define “deep” musculature, which must of course be active to keep the lower leg suspended and bring it “up”, in a way radically different from anatomy. “Contractile tissue which pulls distally on the anterior femoral periostium and the neighbouring septa intermuscularia and which holds the patella cranial by its posterior upper margin” would be a possibility. The formulation is awkward, but it fits the subjective experience and is compatible with what one observes. It should certainly serve the purpose of redirecting the focus away from “muscles” and toward the primary structural reality: fascia.


1. This leaves out “gas” which is found in the lungs (the “pleural bags”) and the intestines, but about which not much is known.

2. The term “normal” is meant in a very narrow sense here. It does not apply to structure but only to the arrangement of the segmental gravity centers in space which is “neutral” as to gravity and normal force. This “normal” arrangement is also called “neutral stance”. Note that segmental rotations do not influence the picture.

3. It is actually “indifferent”.

4. For the sake of analysis the tonus pattern will in the following be assumed to be unchanging and constant in a posture held.

5. “Extension of the body” is so defined as an initial lengthening of its midline. The force effecting it is the “elastic force”.

6. A complication arising with the elbow has been cleared in the paper mentioned.

7. This is not to say that they don’t play a role of a sort. But in the extension mode it is secondary to the mechanism described.

8. This is only true if the center of gravity of the pelvic segment and the hip joint are minimally posterior to the Line.

9. Since nothing goes forward in the beginning, it is also obvious that the center of gravity of the body moves back a little. This does not matter for the movement shown because it is most important that it not go forward!

10. Extension of the spine means here that all physiological curves become flatter and longer. The term does not include a straightening out of a kyphotic lumbar or cervical spine, nor a forced straightening by muscle contraction.

11. Emphasis on complete relaxation of the abdominal wall may appear as overly redundant. But in working with clients, functionally or structurally, one can never be redundant enough in this respect!

12. This revises an earlier description which cannot be considered normal anymore (Notes on S.1. 86/1, p.7).

13. By Wolf Wagner

14. Perhaps they will some day be called “core” and “sleeve” musculature when a meaningful definition of these terms will have been found.

15. The psoas should never “work” in the sense of exerting “brute force”. Responsible for forceful flexion of the hip joint is the iliacus or parts of it.

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