The Science of Breathing Well

Introduction[edit | edit source]

Breathing affects all body systems; these systems in turn influence breathing. Optimal breathing patterns help to maintain homeostasis, but when breathing is disrupted, significant issues can arise.

Physiotherapists are well placed to assess and treat breathing pattern disorders. It is, however, important to understand the science behind optimal breathing in order to understand the relationship between breathing and the quite varied symptoms that occur with dysfunctional breathing. The science of breathing can essentially be broken down into three subcategories:

  • The mechanics of breathing well (ie biomechanics)
  • The physiology of breathing well (ie biochemistry)
  • The psychophysiology of breathing well (or psychology)

The Mechanics of Breathing Well[edit | edit source]

Brief Anatomy Review[edit | edit source]

For more information on the anatomy of breathing, click here, but in brief the respiratory conduction zone consists of the:[1]

  • Nasal cavity
  • Pharynx
  • Larynx
  • Trachea
  • Bronchi and bronchioles

The nose plays an important role in nitric oxide production, which impacts latency and dilation of blood vessels. It is also involved in sterilisation of air in the airways.[2][3] The larynx transports air down to the lungs.

The respiratory muscles are:[4]

  • Diaphragm, which acts as a vital pump
  • Rib cage muscles
  • Abdominal muscles

The thoracic and abdominal cavities essentially form a canister with the larynx and vocal cords on top, diaphragm in the middle and the pelvic floor at the base. All work together to ensure optimal respiration, as well as to maintain / modulate intrathoracic and intra-abdominal pressure.[3]

How Do the Biomechanics of Breathing Influence Other Systems and Organs?[edit | edit source]

Heart[edit | edit source]

Other organs and systems are influenced by the biomechanics of breath, including the heart. The heart is encased in, and moves with, the diaphragm, which influences heart tone.[3] Similarly,  when the diaphragm descends and ascends, the heart is essentially “micro-massaged”, which affects its baroreceptors.[3][5] Baroreceptors are a type of mechanoreceptor which enable information about blood pressure to be sent to the autonomic nervous system.[6]

Heart rate variability (HRV) is also influenced by breathing.[7] HRV refers to the variation in time intervals between heart beats.[7] HRV is an important indicator of health, as well as mood and our ability to adapt. A number of physiological systems influence heart rhythm. Higher HRV generally is a marker of good physiological functioning whereas lower HRV predicts morbidity and mortality. Low HRV is also more common in individuals who have depression, anxiety and chronic stress.[7]

Intra-abdominal and Intra-thoracic Pressure[edit | edit source]

The diaphragm works with the anterior abdominal wall muscles to increase intra-abdominal pressure, enhancing processes such as gut motility, defecation, micturition (urination) and parturition (giving birth).[8]

As mentioned above, the diaphragm acts as a vital pump.[3] On inhalation, its descent decreases intrathoracic pressure and increases intra-abdominal pressure. This acts on the inferior vena cava, helping to push deoxygenated blood into the right atrium. It also compresses the abdominal lymph vessels, which aids lymphatic movement.[8] Similarly, cerebrospinal fluid is pumped into the brain on inhalation and pumped back down on exhalation.[9]

Continence and Voice Quality[edit | edit source]

Continence and vocal quality are also affected as they make up the base and top of the canister.[3]

Contraction of the pelvic floor muscles and diaphragmatic motion correlate with breathing. Moreover, breathing is more effective when the pelvic floor contracts.[10].

The relationship to the diaphragm and vocal quality has been studied most extensively in singing, but it has been found that co-activation of the diaphragm during phonation may impact voice quality.[11][12]

Musculoskeletal System[edit | edit source]

The diaphragm also has a significant impact on our musculoskeletal system. Breathing mechanics affect posture and spinal stabilisation; breathing pattern disorders contribute to pain and motor control deficits and can result in muscular imbalance, changes in motor control and physiological adaptations which result in modified movement patterns.[13]

For instance, a significant correlation between low back pain and breathing pattern disorders has been demonstrated[3] and a recent study by Finta and colleagues found that diaphragm strengthening combined with other training may be beneficial in the management of chronic nonspecific low back pain.[14] A link between chronic ankle instability and altered diaphragm contractility has also been established.[15]

References[edit | edit source]

  1. ↑ Cedar SH. Every breath you take: the process of breathing explained. Nursing Times [online]. 2018; 114(1): 47-50.
  2. ↑ Lundberg JO, Settergren G, Gelinder S, Lundberg JM, Alving K, Weitzberg E. Inhalation of nasally derived nitric oxide modulates pulmonary function in humans. Acta Physiol Scand. 1996;158(4): 343-347.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Clifton-Smith T. The Science of Breathing Well Course. Physioplus. 2020.
  4. ↑ Aliverti A. The respiratory muscles during exercise. Breathe (Sheff). 2016; 12(2):165-168.
  5. ↑ Baekey DM, Molkov YI, Paton JF, Rybak IA, Dick TE. Effect of baroreceptor stimulation on the respiratory pattern: insights into respiratory-sympathetic interactions. Respir Physiol Neurobiol. 2010;174(1-2):135-145.
  6. ↑ Armstrong M, Kerndt CC, Moore RA. Physiology, Baroreceptors. [Updated 2020 Apr 19]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK538172/
  7. ↑ 7.0 7.1 7.2 Steffen PR, Austin T, DeBarros A, Brown T. The Impact of Resonance Frequency Breathing on Measures of Heart Rate Variability, Blood Pressure, and Mood. Front Public Health. 2017;5: 222.
  8. ↑ 8.0 8.1 Bains KNS, Kashyap S, Lappin SL. Anatomy, Thorax, Diaphragm. [Updated 2020 Apr 21]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK519558/
  9. ↑ Clifton-Smith T. How We Breathe Course. Physioplus. 2020.
  10. ↑ Park H, Han D. The effect of the correlation between the contraction of the pelvic floor muscles and diaphragmatic motion during breathing. J Phys Ther Sci. 2015;27(7):2113-2115.
  11. ↑ Leanderson R, Sundberg J, von Euler C. Role of diaphragmatic activity during singing: a study of transdiaphragmatic pressures. J Appl Physiol (1985). 1987;62(1):259-270.
  12. ↑ Salomoni S, van den Hoorn W, Hodges P. Breathing and Singing: Objective Characterization of Breathing Patterns in Classical Singers. PLoS One. 2016;11(5):e0155084.
  13. ↑ Bradley H, Esformes J. Breathing pattern disorders and functional movement. Int J Sports Phys Ther. 2014; 9(1): 28-39.
  14. ↑ Finta R, Nagy E, Bender T. The effect of diaphragm training on lumbar stabilizer muscles: a new concept for improving segmental stability in the case of low back pain. J Pain Res. 2018;11:3031-3045.
  15. ↑ Terada M, Kosik KB, McCann RS, Gribble PA. Diaphragm Contractility in Individuals with Chronic Ankle Instability. Med Sci Sports Exerc. 2016;48(10):2040-2045.
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