We breathe and we live (or is it the other way around). There are many excellent resources on breathing. This article will focus on some of the popular misconceptions of the diaphragm in breathing.
Popular misconceptions (taught world wide and in current anatomy texts)
- Some people speak of chest breathing versus diaphragm breathing. Does this mean that if you breathe with your chest you are not using the diaphragm? If you are moving air into and out of your lungs and still alert for longer than 30 seconds, then your diaphragm is moving. You will use your diaphragm essentially all the time you move air, whether you see your chest or belly primarily moving.
- Only the central portion of the diaphragm moves in breathing. Really?
- The diaphragm is only active on inspiration. Expiration is essentially passive. Hmm-mm.
We will be primarily addressing the second and third misconception listed above.
Brief Anatomy of the Diaphragm
It is a dome shaped muscle when at rest or after the expiration/exhalation phase of breathing.
Here are it’s distal (furthest away from the center-line of the body) attachments:
- Costal or ribs number 7-12
- Lumbar vertabrae number 1-3
- Xypho-Sternal aspect
Here is the proximal (close to center-line of the body) attachment:
- Central tendon
Now there are more complete descriptions of these attachments in most anatomy texts that you can review in the library and on the web. For now I want you to think about this division of distal and proximal attachments for the diaphragm.
Muscular attachments and directions of contraction
The diaphragm is one of the few muscles that does not attach one bone to another. The face is another exception to this popular occurrence of muscular anatomy. Keep in mind that contraction of the diaphragm is occurring between the proximal and distal attachments. It is not occurring between the ribs and the spine. Please keep this picture in your mind. That means that when it contracts in inspiration it is shortening the distance between the proximal attachment (central tendon) and distal attachments. Therefore in simple terms one end is coming closer to the other end. (Although in reality they are both moving to different degrees)
Here in inspiration as the diaphragm contracts you could see that the central tendon would be pulled down. This downward movement of the central tendon causes the lungs to fill with air. Some people only describe the movement of the central tendon in inspiration. This is only partially complete.
Let’s deviate for a moment to looking at the action of your bicep muscles in isolation. Here the biceps connects the forearm bone to the upper arm bone (essentially). The action is to bend the elbow. (Only partially true). So if you bring your hand (distal part) to your shoulder (proximal part), the bicep is moving them closer. This is true only if the shoulder is fixed in space and the hand is free to move (like when you lift up a gallon of milk). If your hand (distal) is fixed to an overhead bar or tree limb and you contract the bicep muscle it brings your shoulder (proximal) closer to the fixed hand (the ole pullup). Similar actions but different parts (attachments) are moving while other parts (attachments) are fixed.
Also notice that the bicep muscle is active in lifting AND lowering in both cases. Let’s take the example of the lifting glass gallon of milk up with you hand. As the milk/hand comes closer to the shoulder the bicep is actively shortening in it’s (concentric) contraction. If the bicep muscle were essentially passive in returning the hand away from the shoulder (in this case the act of lifting), then the glass gallon would possible slam into the table below. This may be a bit laborious for some to read, but stay with it if you can keep your mind focused here. Lowering of that gallon of milk can be observed with the bulging of the bicep muscle seen in both directions. The opposing tricep muscle here is essentially inactive. This is true also in the pullup example. The same muscle is active in raising and lowering. (This dual action will be the same in the diaphragm)
The bicep is actually active in lifting and lowering of the milk/hand. This is respectively the concentric (shortening activity) and the eccentric (lengthening activity) of the muscle. Let me labor this point further. There are still authors and teachers who teach that muscles can only contract in one direction (often stated about the diaphragm). They say it takes a second muscle or force to activate the second direction. Of course the force of gravity is always present. But to say that the diaphragm is passive in exhalation is an error.
Diaphragmatic function in inspiration and expiration
The central nervous system sends a signal via the phrenic nerve (the anatomical origin exits through the neck via the chest cavity to the diaphragm) to activate the diaphragm. The diaphragm is involved in both concentric contraction and eccentric contraction. The latter has been poorly described if at all. I feel that this error is due to very poor functional knowledge of the way things actually work. These explanations of contraction and then relaxation lead one to speak of one phase being active and the other passive. This idea becomes erroneous and the propagated to the detriment of proper functional training of the diaphragm.
The diaphragm can fix either the proximal or distal end and move it’s opposite.
- In inspiration, if the rib and sternal attachments are fixed (by the action of the abdominal and costal muscles), the action of contraction of the diaphragm will lower the central tendon. We then see the belly protrude forward. Often this type of inspiration/inhalation is referred to as belly breathing.
- Another style of inspiration is when the central tendon is held in a static position (often by an increase in intra-abdominal pressure, which impedes the central tendon from descending). Then the action of diaphragmatic contraction will cause the ribs to elevate and expand the interior dimension. Often this style of three dimensional costal breathing of the lower rib cage is referred to as diaphragmatic breathing.
- Another style would be a combination of these proximal and distal attachments being held in part and allowed to move in part also.
- In expiration, the diaphragm is returning to it’s resting/starting position of a dome like appearance. The diaphragm is just not flaccid during this phase, as often suggested by the word passive exhalation.
Eccentric phase of the diaphragm
When (in expiration/exhalation) the diaphragm returns, it is still contracting (in it’s lengthening return to rest). Let’s look at setu bandasana. This is the bridge pose in yoga where you lie on your back with your knees bend with feet standing on the ground.
When you inspire, you can see that the diaphragm must push against the weight of the abdominal contents. Literally the diaphragm muscle is lifting this weight of the internal organs in this pose. It actually is quite strengthening for the diaphragm, as are all inverted postures/asanas. Now when you exhale, often slowly, the return of the diaphragm muscle if it was passive, would be a rapid release of the abdomen. This erroneous belief of a passive diaphragm in this case would create a dramatic “whoosh” of exhaled air. We know this is not what regularly happens, but quite the opposite. This slow release is because the diaphragm is actively lowering the belly contents as it returns back to it’s starting position higher up in the chest cavity.
This eccentric phase of the diaphragm is occurring on all positions. It can be more easily appreciated in inverted postures.
Orchestration of breathing
There are many styles and names of various ways we inhale and exhale. We can orchestrate the different patterns of breathing through our positions and activations/inhibitions of all the muscles involved. There are many other important muscles of breathing. The internal and external intercostals will not be discussed in any detail. They are extremely important along with the abdominal muscles, especially the obliques in helping to choreograph the visible expansion and contraction of the chest and belly volumes.
Just realize that in breathing the diaphragm is always involved in moving the air (if we are conscious for more that 30 sec). Even in upper chest breathing (vs just saying chest breathing), the diaphragm is responsible for the intake of air. In paradoxical breathing, where the chest expands and the belly is pulled up and inward, the diaphragm is still the prime mover. In this style of breathing, radiography has shown even an elevation of the diaphragm. Realize that the distal costal attachments are pulling outwards to such an extreme extent that the diaphragm is still contracting even though it is slightly doming up in the chest cavity.
So what! Literally if you are still reading you may be wondering something similar. If not OK! Either way at this time we should look at the so what factor. Knowing that the diaphragm is active in both phases of breathing will definitely affect your training of breathing. Breathing for most people is inefficient. So many people are suffering unnecessarily because they are not breathing well.
Also people are not re-training their breathing patterns properly. We must include this eccentric phase of the diaphragm in our training. I think we do in some ways now when we prescribe for people to breath slowly. The exhalation phase that is active can lead to greater awareness of the breath flow. Knowing that you are actively working both phases of the breath from the diaphragm will translate into better training regimens. Adding resistance to the eccentric phase of breathing is very important. Many people have a very weak diaphragm. So the use of an abdominal sandbag or using inverted positions becomes very important. Also I really like the Makarasana position or crocodile pose to help here. The Himalayan Tradition in teaching proper diaphragmatic breathing commonly uses this asana.
Now when you train your breathing patterns include this active exhalation model of the diaphragm. See if this concept helps focus and enhances your training. Let me know what you find out.
The best in your training efforts.
Please contact me if I can be of further assistance.