Functional (or optimal) breathing using the nose and diaphragm plays a very major role in regulating the two aspects of the autonomic nervous system – the sympathetic and parasympathetic aspects. It serves to balance them. Something which, as observed from previous discussion, is not achieved by mouth or over-breathing which serves to maintain us in sympathetic nervous system dominance (or ‘fight or flight’ responsiveness) for most of our lives. As most of us have developed into over-breathers over our lives, this pertains to us all.
The diaphragm in particular, plays a major role in sympathetic/parasympathetic nervous system balance in two ways:
Balance between the contraction and subsequent recoil of the diaphragm helps balance SNS & PSNS activity.
The predominance or abundance of SNS and PSNS in different parts of the lung.
Firstly, the contraction of the diaphragm on inhalation requires sympathetic nervous system input to fire the contraction and resultant flattening of the diaphragm which draws the lungs down and allows air to fill the lungs – particularly the lower lobes. The exhalation however involves switching off the SNS driven contraction of the diaphragm allowing it to return or recoil back to its original position. This is driven by PSNS activation which acts as a complementary opposition (in this case) to the SNS. As stated, it relaxes the diaphragm or switches off the contraction leading to the recoil or return of the diaphragm to its resting state.
Most over breathers use the accessory muscles of breathing as the dominant muscles of respiration, to the detriment of optimal diaphragmatic breathing. As such the diaphragm becomes weak or atonic and loses its flexibility. We have found via CapnoTrainerTM biofeedback equipment and general clinical observation that, over-breathers have most difficulty controlling their exhalation. It ends up being shorter in duration than the inhalation. Diagnostic norms suggest, however, that the inhalation:exhalation ratio is ideally 2:3, and therefore the exhalation is ideally 50% longer than inhalation.
As a result of this imbalance in the inhalation:exhalation ratio, the ANS becomes SNS dominant. At Breathing Dynamics we focus on creating a balance between inhalation and exhalation and therefore in the autonomic nervous system.
Secondly, as previously stated, mouth breathing originally (or from an evolutionary perspective) served as an emergency function in response to an acute stressor. Generally, the chest muscles are mostly used when mouth breathing (instead of the diaphragm – unless you have received previous training) which predominantly fills the upper and middle lobes of the lungs, and less so the lower lobes. The upper lobes of the lungs are rich in SNS receptors which, when activated, serve to accentuate the requirement of the body to respond in emergency fashion – or via a ‘fight or flight’ mechanism. This serves a specific function. An example of this would be when we gasp in response to being frightened or surprised.
But it was not designed to be our predominant mode of functioning.
On the other hand, when breathing uses predominantly the diaphragm (as in optimal breathing), the larger, lower lobes of the lungs are comfortably filled allowing for more gas exchange. And respiration is far more efficient. In addition, the lower lobes are rich in PSNS receptors which allows for a balance between the PSNS and SNS and a correction of our predominant ‘fight or flight’ functioning.
When breathing ‘diaphragmatically’ through the nose it is common to experience relaxation and a calming of the mind. It also gives athletes greater access to ‘zone like’ or ‘alpha’ states during exercise or competition, which generally involve higher levels of PSNS activation than in normal waking states.
The table below shows a comparison in terms of effects between breathing with the diaphragm as the driver of respiration as opposed to predominantly using the chest muscles or other accessory breathing muscles. Whilst, not all of the points listed in the table are covered in the general information, they are covered when we introduce the ‘Breathing Dynamics’ optimal breathing rhythm in courses or via online training modules.
|Diaphragmatic Breathing||Breathing Using Accessory Muscles|
|Fills blood rich lower lobes of the lung first.||Fills predominantly upper & middle lobes of the lungs.|
|Allows use of full lung capacity for gas exchange and removal of wastes.
Creates a more rhythmic, reduces breathing rate via control of the recoil on exhalation.
Activates PSNS receptors in lower lobes. PSNS and SNS are balanced.
|Full use of lungs compromised.
Breathing rate is elevated and rhythm is more random.Activates SNS stress receptors in upper/mid lobes and SNS dominates.
|Stimulates ‘rest and digest or rejuvenate’ response.||Activates ‘fight or flight’ response.|
|Diaphragm is strong and elastic.||Diaphragm becomes weak and atonic.|
|Allows for relaxed, rhythmic and efficient respiration.||Requires more work and higher breathing & heart rate to achieve efficient respiration.|
|Sinuses remain clear due to constant air flow through them.||Sinuses become congested from discontinued use.|
|Facilitates lymphatic drainage and circulation to heart, lungs, ribs and chest via the ‘pump’ like action of the diaphragm.||Lymphatic drainage and circulation to heart, lungs, chest and rib cage compromised.|
|The ‘Pump’ like action also facilitates efficient functioning of digestive organs (i.e. peristalsis), urinary organs and sexual organs all located in the abdominal cavity.||Function of organs in the abdominal cavity compromised.|
|Ribs and chest allowed to move in their full range of activity and remain flexible.||Ribs and chest become inflexible.|
|Thoracic spine remains flexible.||Thoracic spine at insertion of ribs becomes stiff and rigid.|
|Neck and shoulders not overworked.||Neck and shoulders become tight.|
Relatively recently, a third subsystem of neurons that have been named ‘non-adrenergic and non-cholinergic’ neurons (because they use nitric oxide as a neurotransmitter) have been described and found to be integral in autonomic function, particularly in the gut and the lungs.
Nitric oxide has been found to act as a neurotransmitter, immune-regulator and vasodilator.
Some of the actions of nitric oxide include:
- Regulation of blood pressure
- Boosting the immune system
- Fighting microorganisms such as bacteria and viruses
- Fighting cancer
- Increasing blood supply to cells.
- Aiding in muscular control, balance and coordination.
- It has also been suggested to protect against cardiovascular disease, impotence, diabetic retinopathy, Alzheimer’s Disease and Parkinson’s Disease.
A recent study comparing nitric oxide production in nose breathing and mouth breathing found that the nasal passages produced a significantly higher amount of nitric oxide than mouth breathing did. In fact, 50% of exhaled nitric oxide is produced in the nose. A further study found that nitric oxide is absorbed in the nose as well as being produced there.
Also, as exercise intensity increased, the levels of nitric oxide increased in nose breathing but not in mouth breathing. So, it can be implied that, when under high levels of stress, nose breathing will offer stress mediating effects via nitric oxide that can protect against the deleterious effects produced by long term stress, whereas mouth breathing will not.