The Effect of Posture on the Diaphragm

Original Editor - Carin Hunter based on the course by Rina Pandya
Top Contributors - Carin Hunter

Effect of posture on Diaphragm[edit | edit source]

When optimising diaphragm function, a vertical length of the body is needed. We need both the thoracic and the abdominal cavities to be long enough for the diaphragm to create negative and positive pressures during inspiration and expiration. A patient needs to be able to take a deep breath down to the base of the lungs so the ribs can flare out, the diaphragm can dropdown.

Forward head posture (FHP) and Kyphosis have been shown to alter the breathing mechanism including diaphragm mobility.

Forward head posture[edit | edit source]

The increased degree of FHP has a bearing effect on chest expansion and respiratory muscles activities which can lead to reduced alveolar ventilation. [1] This could be a result of temporary entrapment of the phrenic nerve, which supplies the diaphragm, reduces neural activity, and consequently weakens diaphragm activity. [2]

Hodges et al deduced that altered diaphragm function leads to core muscles instability, which will further lead to other systemic and musculoskeletal disorders including spinal instability. [3]

A FHP disturbs the normal respiratory biomechanics[4] and therefore, results in expansion of the upper thorax and contraction of the lower thorax. The consequence of these changes is decreased respiratory function. [5]

For the diaphragm to be most effective during breathing we need to:

  1. Restore normal length-tension relationship
  2. Improve mobility and expansion in the chest wall
  3. Relieve the load on accessory respiratory muscles in the neck[6]

Kyphotic posture:[edit | edit source]

Kyphosis can be a result of torticollis and FHP leading to the development of a secondary thoracic curve to compensate for the flattening of the cervical spine curve.  Alteration of cervicothoracic mobility impairs normal breathing mechanics by reducing diaphragm mobility and strength. [7]

When an individual is slumped with a kyphotic posture, this approximation of ribs and pelvis has been shown to increase intra-abdominal pressure making movement of the diaphragm difficult. This can lead to:

  1. Reduced lung capacity
  2. Reduced inspiratory flow [8]
  3. Decreased Forced Vital Capacity[9]

When assessing a patient with FHP and torticollis, respiratory function should be included. When assessing respiratory function, the SNIP tool (Sniff Nasal Inspiratory Pressure)[10] could be used. It is simple, easy to use and can be integrated into practice for screening individuals with mal-posture. [11]

Posture in an ICU Bed[edit | edit source]

Often to make a patient comfortable, pillows are placed under the head and under the knees. The patient is now lying in a hammock position in the bed. These steps are in fact reducing the ability of the diaphragm to function.

Poor ICU positioning results in:

  • Increased forward head angle
  • Increased apical breathing
  • Decreased diaphragmatic breathing


  1. Anterior neck muscle tightness
  2. Cervical extensor muscle weakness
  3. Diaphragmatic weakness.

Other factors to consider[edit | edit source]

Diaphragm influences:

  1. Oesophageal function
  2. Digestive function
    • The peristaltic movements, massaging of the abdominal contents
  3. Vascular function with the blood pressure
  4. Immune system
    • The diaphragm helps with immunity because it's creating fresh flow and assists with the absorption of nutrients and vitamins.

References[edit | edit source]

  1. Okuro RT, Morcillo AM, Ribeiro MÂ, Sakano E, Conti PB, Ribeiro JD. Mouth breathing and forward head posture: effects on respiratory biomechanics and exercise capacity in children. Jornal Brasileiro de Pneumologia. 2011;37:471-9.
  2. Lane MA. Spinal respiratory motoneurons and interneurons. Respiratory physiology & neurobiology. 2011 Oct 15;179(1):3-13.
  3. Hodges PW, Gurfinkel VS, Brumagne S, Smith TC, Cordo PC. Coexistence of stability and mobility in postural control: evidence from postural compensation for respiration. Experimental brain research. 2002 Jun;144(3):293-302.
  4. Triangto K, Widjanantie SC, Nusdwinuringtyas N. Biomechanical Impacts of Forward Head Posture on the Respiratory Function. Indonesian Journal of Physical Medicine & Rehabilitation. 2019;8(02):50-64.
  5. Koseki T, Kakizaki F, Hayashi S, Nishida N, Itoh M. Effect of forward head posture on thoracic shape and respiratory function. Journal of physical therapy science. 2019;31(1):63-8.
  6. Haghighat F, Moradi R, Rezaie M, Yarahmadi N, Ghaffarnejad F. Added Value of Diaphragm Myofascial Release on Forward Head Posture and Chest Expansion in Patients With Neck Pain: A Randomized Controlled Trial.
  7. Chaitow L. Functional movement and breathing dysfunction. Journal of bodywork and movement therapies. 2016 Jul 1;20(3):455-6.
  8. Lin F, Parthasarathy S, Taylor SJ, Pucci D, Hendrix RW, Makhsous M. Effect of different sitting postures on lung capacity, expiratory flow, and lumbar lordosis. Archives of physical medicine and rehabilitation. 2006 Apr 1;87(4):504-9.
  9. Haque MF, Akhter S, Tasnim N, Haque M, Paul S, Begum M. Effects of different sitting postures on forced vital capacity in healthy school children. Bangladesh Medical Research Council Bulletin. 2019 Aug 7;45(2):117-21.
  10. Prigent H, Lejaille M, Falaize L, Louis A, Ruquet M, Fauroux B, Raphael JC, Lofaso F. Assessing inspiratory muscle strength by sniff nasal inspiratory pressure. Neurocritical care. 2004 Dec;1(4):475-8.
  11. Zafar H, Albarrati A, Alghadir AH, Iqbal ZA. Effect of different head-neck postures on the respiratory function in healthy males. BioMed research international. 2018 Jul 12;2018.