By: Stephen Osterer – April 7, 2013
The topic of diaphragmatic breathing has become a bit of a buzzword lately and as a student, I wanted to lay out some of the prevalent concepts surrounding its function, assessment, and correction in order to strengthen my understanding. This is by no means a full systematic review of the literature, but a base for conversation and debate on the subject. Before we go any further let’s first discuss some of the relevant anatomy.
The diaphragm is a dome-shaped musculotendinous structure that divides the thoracic and abdominal cavities. Because of it’s gross fascial connections and location in the body, discerning where the diaphragm actually begins and ends is more of a discussion on cadaveric dissection protocol than human anatomy – another debate in of itself and too long for this post. On a basic level, it can be divided into three different parts – the sternal, costal and lumbar parts. Of particular interest are the ‘three pillars’ of the lumbar aspect that connect to the anterior bodies of L1-4, and via its arcuate ligaments, the psoas and QL. Finally, the muscle provides openings for the vena cava, esophagus and abdominal aorta.
It receives motor innervation from the phrenic nerve (C3-5), which is under the tight control of the retroambiguus nucleus in the medulla. The branches from the last four to five intercostal nerves also assist the motor supply to the diaphragm. Moreover, it has been shown that the vagus nerve may anastamose the phrenic nerve as it passes through the diaphragm and subsequently innervate the crural region.1
We now shift our focus onto some of the theories for its function.
Chemoreceptors of the carotid and aortic glomerula, the lungs and the brains, all provide chemical information to the medulla. Depending on the afferent information different impulses are then conducted to the diaphragm and cause subconscious respiration. When everything is working properly, contraction of the diaphragm results in the flattening and inferior pull of its crural domes. This increases the intrathoracic volume and decreases intrathoracic pressure, allowing air to be taken into the lungs. This in turn decreases the volume of the abdominal cavity and increases intrabdominal pressure. Visually, this should result in a nice 3-dimensional ‘belly’ expansion with inspiration.
Recently there has been an emphasis on the crural part of the diaphragm acting as a component of the anti-reflux barrier. It has been proposed that the crura serve as an external esophageal sphincter and that a decrease in diaphragmatic or phrenic nerve function may result in a decreased lower esophageal tone, and therefore susceptibility to acid reflux. 2,3 Theoretically, an improvement in diaphragmatic excursion will strengthen this barrier and aid in the treatment of acid reflux.
Postural Stabilization Function
Hodge’s group out of Queensland and Kolar’s group from Prague have provided a lot of research into the diaphragm’s duel function of inspiration and stabilization.4,5,6,7 Through their work, they have shown that the diaphragm contributes to postural control and trunk stabilization during dynamic limb movements, irrespective of respiratory activity.
This concept is furthered by the Prague School of Rehab’s DNS courses as being a primary neurodevelopmental process crucial in the subconscious feed forward activation of the integrated spinal stabilization system (ISSS); deep cervical flexors, multifidus, diaphragm, pelvic floor, and abdominal wall.8 As a baby develops the proper sequencing of co-activation of the ISSS with increased intraabdominal pressure it will result in proper joint centration, spinal stability and the ability for the baby to develop sequentially through motor milestones. Without proper function of the diaphragm we cannot achieve a stable base for the development of these motor patterns and must derive stability through high threshold strategies and non centrated positions.
Lymphatic and Venous Flow
The implications of proper diaphragmatic breathing and lymphatic and venous flow has been understood in manual medicine for decades. During inhalation, the diameter of the inferior vena cava decreases providing a rhythmic tone for venous flow. Moreover, lymphatic flow leads from the peripheral diaphragm to the central tendon and eventually into the thoracic duct and venous system. The efficiency of this process reaches its climax during slow and deep respiration involving the diaphragm.11 Recent research has shown that correct activity of the diaphragm may actually help to prevent venous drainage problems.9 The proper rhythmicity and stretching of the diaphragm is important to lymphatic absorption and therefore incorrect function can negatively affect the entire lymphatic system.10,11
So as we develop, baby first learns to breathe, baby then learns to stabilize, and then learns to move. Baby explores the external environment with proper diaphragmatic function and lives happily ever after? Clearly not. Chest breathers are the norm in today’s society and the very concept of diaphragmatic breathing to the general population is largely unheard of. So what gives? Why do we lose this basic movement pattern? Chaitow explains in his work that modulation of the act of breathing results from many possible input sources.12 Strong emotions such as chronic anxiety, apprehension, time urgency, resentment and anger manifest somatically in some people as excess breathing, as if preparing for exertion. Take a look at the diagram below.
Looking at the big picture, anything sympathetically driven may alter our breathing patterns and attenuate or amplify any current existing dysfunction. Left unchecked, this vicious mind-body circle can result in a host of different problems. Mix in how this may affect the brain’s nociceptive neurosignature and consequent pain output and now you’re looking at a complex internal environment.
In the next article, we will look at the consequences of abnormal breathing mechanics from a physiological, mechanical and psychological standpoint and what we can do in an attempt to correct them.
Pertinent points thus far:
- Diaphragmatic breathing may form the basis of proper respiration, postural stabilization, prevention of gastroesophageal reflux and promote proper lymphatic and venous dynamics.
- Proper diaphragmatic excursion may be thought of as the primary movement pattern in the neurodevelopmental process.
- We lose optimal breathing patterns due to a variety of emotional and behavioural inputs.
- This may create a vicious cycle of negative physiological, psychological and mechanical effects.
About the Author
Stephen Osterer is currently finishing his Doctorate of Chiropractic degree at the Canadian Memorial Chiropractic College. While completing his Bachelor’s of Science and pitching for the Cornell Big Red he developed a passion for manual therapy, rehabilitation and athletic performance. When he is not hitting the books or serving as a pitching coach, you can find him listening to the Joe Rogan’s Experience podcast and perfecting his guacamole.
If you’d like to connect with him you can drop him an email or find him on twitter at:
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2.Eherer AJ, Netolitzky F, Hogenauer C, et al. Positive effect of abdominal breathing exercise on gastroesophageal reflux disease: a randomized, controlled study. Am J Gastroenterol. 2012;107(3):372-378
3.Bitnar P., Kolar P. et al. Diaphragm function in GERD patients: PFT assessment with extended esophageal manometry. Presented at: ERS Congress Barcelone, 20. Congress of European Respiratory Society, Barcelona 2010, Spain 2010. http://rehabps.com/REHABILITATION/Literature_Research_files/Bittnar%20GER_2_1_1.pdf
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10.Moriondo A, Bianchin F, Marcozzi C, Negrini D. Kinetics of fluid flux in the rat diaphragmatic submesothelial lymphatic lacunae. Am J Physiol Heart Circ Physiol. 2008;295(3):H1182-H1190
11.Byeon L, Choi JO, Yang JH, et al. The response of the vena cava to abdominal breathing. J Altern Complement Med. 2012;18(2):153-157
12.Chaitow L, Bradley D, Gilbert C. Multidisciplinary Approaches to Breathing Pattern Disorders. 1. Edinburgh: Elsevier, 2002.