The Case for the 3-D Diaphragm © Leslie Kaminoff

This is a rough draft of some material I’ve been working on for the past couple of months. It is written in a somewhat technical style that presupposes a certain level of anatomical knowledge in the reader.
It can be viewed as a follow-up to the discussion of “Breath Flow” archived on e-Sutra. It is also a preview of some of the key points I’ll make in my presentation to “The Future of Breathing” symposium at Kripalu this Fall.

The Case for the 3-D Diaphragm © Leslie Kaminoff

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Enjoy, and (as always) let me know what you think.



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copyright 2004, 2005 Leslie Kaminoff and The Breathing Project, Inc.
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The Case for the 3-D Diaphragm
By Leslie Kaminoff
copyright 2004, 2005 Leslie Kaminoff and The Breathing Project, Inc.

There is no question that teaching people the efficient use of the diaphragm is very important. Problems arise, however, when the action of the diaphragm is viewed in the limited context of its effect on movements in only the abdominal region of the body. This action, often referred to as “belly,or abdominal breathing” represents only one dimension of the increase in volume that the diaphragm creates in the thoracic cavity; the vertical. I will explain how the diaphragm is capable of increasing all three dimensions of the thoracic cavity, namely: the vertical (top-to-bottom), the transverse (side-to-side) and the sagittal (front-to-back).

What are the problems that arise from this limited perspective?

Many people who teach and learn abdominal breathing determine the quality of their breathing only by its location in the torso, i.e.: abdominal movement is good, thoracic movement is bad. This ignores the critical issue of effort. It is possible (indeed, quite common) to do tense belly breathing, just as it is possible to do relaxed chest breathing. In addition, this top/bottom distinction is only one-dimensional, as it ignores important lateral and sagittal breath movements.

By equating abdominal shape change with diaphragmatic breathing and thoracic shape change with accessory (non-diaphragmatic action), a false distinction is perpetuated between diaphragmatic and non-diaphragmatic breathing. ALL breathing is diaphragmatic (except in cases of paralysis, such as quadriplegia). It is untrue and damaging to suggest to someone who predominantly exhibits thoracic shape change that they are not using their diaphragm. They are using it inefficiently, and perhaps in combination with many other unnecessary muscles, but they are certainly using the diaphragm.

By accepting abdominal breathing as “correct,” learning and automatizing the habit, the breathing mechanism becomes less adaptable. Being stuck in any pattern will create problems, regardless of how useful that pattern may be in a given context.

Please keep in mind that it is not my intention to negate or disparage the enormous benefits that derive from learning the conscious use of the diaphragm thru abdominal breathing. It is my intention to literally bring a more three-dimensional approach to the field of breath training.

Breathing as Shape-Change

To clarify this perspective on the breath, it will be useful to clearly define what I mean by breathing. In the context of this argument, the term breathing is being limited to the mechanical act of increasing and decreasing thoracic volume; in other words, inhaling and exhaling.

A useful definition for breathing is: “The shape-change of the thoracic and abdominal cavities.” Both cavities – by definition – must change shape in the act of breathing; the diaphragm is the floor of one and the roof of the other. There is, however, a significant difference in how the two cavities change shape in the act of breathing. The thoracic cavity – like a bellows – changes its shape and volume, while the abdominal cavity – like a water balloon – changes its shape, but not its volume. This is why it is misleading to describe an abdominal breath as an “expansion” of the belly; it is actually a bulging of the abdomen, who’s contents are non-compressible or expandable. This is in the context of breathing only; in the context of other life-processes, the abdominal contents will of course fill and empty, thus changing their volume. It should be noted though, that any increase in abdominal volume will require a decrease in overall thoracic volume. This is why it is temporarily harder to breathe “on a full stomach” and chronically harder to breathe if you are obese or pregnant.

The muscles that control the shape-change of breathing are usually categorized as “muscles of inspiration” and “muscles of expiration.” This can be confusing, since some “exhaling” muscles can be quite active during an inhale, and vice versa. I prefer to categorize the muscles by their effect on thoracic volume; there are muscles that act to increase thoracic volume (principally the diaphragm), and there are muscles that act to decrease thoracic volume (primarily the abdominals and internal intercostals).

A New Definition of Accessory Muscle Action

Muscles other than the diaphragm that can increase thoracic volume are commonly referred to as accesory muscles of inspiration, and these include the external intercostals, the scalenes, the strenocleidomastoids, the pectoralis minor, the serratus anterior, and others that must work to stabilize them.

There are no accessory muscles of thoracic volume reduction due to the fact that they are ALL accessory to the passive elastic recoil that produces exhalation in a relaxed state.

Since the contraction and release of the diaphragm alone is capable of producing both the inhale and the exhale, a case could be made for referring to ALL muscles of throaco-abdominal shape-change other than the diaphragm as accessory.

Of the accessory muscles of thoracic expansion, the external intercostals are most important to understand. Although the diaphragm is capable of expanding the ribcage without their help (see below), they are frequently involved in thoracic breath movements. It has been argued that ANY intercostal muscle – because of its location between the ribs – is incapable of expanding the ribcage by virtue of the fact that muscles can only shorten; therefore it would be obvious that a shortening muscle lying between the ribs could only draw those ribs closer to each other in an exhalation.

The above argument would hold up if it were not for the fact that the space between the ribs actually remains constant during all phases of breathing, and the changes in volume of the ribcage are brought about by the SLIDING of the ribs in relation to each other during respiration. The intercostals, being arranged in perpendicular layers oblique to the direction of this rib sliding are, in fact, ideally suited to assist in respiratory movements.

A useful analogy of the relationship of the diaphragm to the accessory muscles is the relationship between a car’s engine and its steering mechanism. The motive power for the car is provided by the engine, but you can’t steer the car with the engine; that is the job of other structures. In a similar way, the diaphragm is the engine of thoraco-abdominal shape-change (breathing), while the accessory muscles modify, or “steer” the shape-change in a particular direction (e.g. “belly breath” or “chest breath”).

How the Diaphragm Expands the Ribcage in 3-D

A closer look at how the thoracic cavity changes its shape reveals several facts:

The best-known fact is that the contracting muscular fibers of the diaphragm pull the central tendon downward, lowering the floor of the cavity, thus increasing its vertical dimension. This is a description of the famous “abdominal breath.”

A lesser-known fact is that the contracting fibers of the diaphragm pull the base of the ribcage upwards, causing the ribs to hinge at their costovertebral articulations, thus increasing the transverse and sagittal dimensions of the thoracic cavity. This is why it is correct to say that the diaphragm creates three-dimensional expansion of thoracic volume.

Like many muscles, the diaphragm can move its insertion towards it origin (central tendon towards base of ribcage), or its origin towards its insertion (base of ribcage towards central tendon). It’s all a question of which end of the muscle is mobile, and which is stable. From this perspective, a belly breath is the result of stabilizing the diaphragm’s origin and mobilizing its insertion, while a chest breath is the result of stabilizing the diaphragm’s insertion and mobilizing its origin.

Without this three dimensional perspective on the relationship between diaphragmatic and accessory action, the role of the “yogic locks” (bandhas) cannot be integrated in any meaningful or useful way by the yoga practitioner.

Limited Direct Control of the Diaphragm

Our direct control over the action of the diaphragm is limited to its timing. We can accelerate or retard its contraction within a range of choice that is severely limited by physiological barriers. Keeping this in mind, it is important to note that specific breathing patterns are not directly brought about by any changes in the action of the diaphragm itself; all it knows how to do is to shorten its fibers, and then stop shortening its fibers. The nearly infinitely variable breath patterns are created by the accessory muscles’ ability to stabilize various regions of the thorax and abdomen while the diaphragm is doing its work. Of course, uncoordinated action of the accessory muscles can lead to both acute and chronic dysfunction of the diaphragm, while the coordinated action of the same muscles leads to increased breath and postural integrity.

This is why it is misleading to refer to breathing exercises simply as “diaphragmatic training.” Breath pattern retraining can more correctly be referred to as accessory/diaphragm coordination.

The Unobstructed Breath

Of course, it’s possible to release all of the diaphragm’s stabilizing muscles, and allow its origin and insertion to freely move towards each other. This is the definition of an “unobstructed breath.” This rarely occurs, as the need to stabilize the body’s mass in gravity will cause many of the respiratory stabilizing muscles to remain active through all phases of breathing. The goal of breath training (on a planet with gravity anyway) is to create the most efficient (least obstructed) postural/breath patterns possible in an ongoing context of body position/movement and effort/intention.

Breath and Posture

Since the diaphragm, in an unobstructed state, will create 3-D shape change in the thorax, intentionally isolating that shape change in the abdominal region requires one to block the other dimensions of movement. In other words, isolated abdominal breathing requires the contraction of the muscles that restrict rib movement. Furthermore, it also requires the relaxation of the abdominal wall. By persistently breathing in this pattern, one will develop a chronic tightness in the thoracic structures that support the shoulder girdle and head, as well as a chronic weakness in the abdominal wall, which provides support for the lower spine. In short, habitual abdominal breathing interferes with effective postural support. It is precisely this action of disengaging postural support that can make abdominal breathing useful for supine relaxation (if it’s done in a non-tense manner). Significant problems will arise if that pattern persists upon standing up, for the breath will be prevented from adapting to the demands of vertical support.

The Emotional Connection

It should be noted that the pattern described above also limits emotional flexibility, as it habitually reduces the sensory perception of space and movement within one’s chest and abdomen – the metaphorical “heart and gut centers” we all seem to need more connection with. In short, although belly breathing may reudce some stress symptoms in its practitioners, getting stuck in that pattern presents the very real possibility of reinforcing one’s emotional defense mechanisms.

Think of what you do in your belly to protect yourself from a punch; now picture doing that more or less all the time on a subtle, subconscious level. Now picture moving that tension forward and back as you breathe, and you’ll understand how many people do their abdominal breathing without ever really releasing the underlying tension.

In other words, moving your belly tension around with your diaphragm through “abdominal breathing” may provide some very real short-term benefits, but releasing the tension altogether requires a more comprehensive, system-wide understanding of the breath.


In a fundamental way, this relationship of breathing patterns to the critical issues of support and release forms the methodological basis of yoga practice. Breath and posture are different ways of viewing the same thing.

Breathing is how we mobilize the space through in our bodies, and posture is how we stabilize our bodies in space.

This perspective is clearly expressed by Patanjali in the second chapter of the Yogasutra when he defines asana practice as Sthirasukhamasanam: Sthira (stability) and Sukha (ease) are the dual qualities of Asana (yoga posture).

Another take on Sthira and Sukha relates those terms to the exploration – on all levels – of the healthy relationship between boundaries and space. This includes our sensory, emotional and conceptual spaces – but it all starts with getting the physical spaces to cooperate in a harmonious way.

3 thoughts on “The Case for the 3-D Diaphragm © Leslie Kaminoff”

  1. This material may be of interest. In particular, look at the Cherniack diagram to understand how the ribs move, in two distinct ways.
    Note, the diaphragm pulls the rib cage structures INWARD.
    The External Intercostals pull the rib cage both outward and upward, to achieve the so-called “Bucket Handle” movement. This is a cascade and multiplier effect, from top to bottom, the upper rib action supporting the rib below it. This is what permits the diaphragm to move to a position of mechanical advantage.

    “Dynamic Hyperinflation physiology: Implications for Chest Physiotherapy”

    You might find my comments under “COPD/Emphysema” on my web site of some interest.

    Indeed, the chest wall / diaphraagm interaction is a complex three dimentional matter.

  2. I would plead for a review of the priorities of in considering the differences between pranayama and western views on respiration, which cannot be accepted as being scientifically fundamental and basic. This is because the role of upper airway resistance in boosting and not hindering breathing as in ujjayi or bhastrika is not accepted in the Western World, because its concepts are based on the bellows model of breathing which does not provide any basis for the “ujjayi effect”. Breathing orally through a gap formed between a finger and the pursed lips will instantly demonstrate this positive correlation between gap reduction and breath volume. True, breathing by this route cuts out nose-lung reflexes, but the suction pressure effect is very impressive.

    Furthermore, breathing at least in some situations acts mechanically on the solar plexus or manipura chakra with an up-regulating effect on the sympathetic nervous system thus causing an increase in airway calibre.

    Another point is that western medicine seems to overlook the fact that inhaling is prevented by minimizing upper airway resistance, probably because the inspiratory muscles are coordinated and have to be coordinated by tension sensors in them. Otherwise operation of the diaphragm might cause the rib cage to collapse. With no suction in the lungs, the muscles could not communicate with each other via the lung air. Regards, Richard Friedel

  3. Hi Leslie,
    Thank you for this article. I greatly admire your work and I am grateful for all the wonderful knowledge that I have learned from you. I smile to myself whenever I hear you say that “all breathing IS diaphragmatic”. Indeed, I agree. There is an exceptional case though. Morris E Goodman was in a plane crash and his diaphragm stopped working. Miraculously, he managed to use his abdominal muscles to breathe on his own again, after being hooked onto machines that helped him to breathe.

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