The Effect of Posture on the Diaphragm

Original Editor - Carin Hunter based on the course by Rina Pandya
Top Contributors - Carin Hunter, Jess Bell, Lucinda hampton, Merinda Rodseth, Kim Jackson and Ewa Jaraczewska

The Effect of Posture on the Diaphragm[edit | edit source]

Posture has a significant impact on the function of the diaphragm.[1] In order to optimise diaphragm function, vertical length is needed - i.e. the thoracic and abdominal cavities need to be long enough for the diaphragm to create negative and positive pressure during inspiration and expiration.[2] A patient must be able to take a deep breath down to the base of the lungs, so that the ribs can flare out and the diaphragm can descend.[2] A detailed discussion of breathing is available here and here. However, specific postures such as forward head posture (FHP) and kyphosis have been found to affect breathing mechanics, including diaphragm mobility.[3]

Forward Head Posture[edit | edit source]


FHP is "a poor habitual neck posture that is defined by hyperextension of the upper cervical vertebrae and forward translation of the cervical vertebrae".[4]

FHP affects chest expansion and the activity of the respiratory muscles, which can lead to reduced alveolar ventilation.[3][5] Zafar et al.[3] found that induced FHP in healthy subjects has an immediate impact on respiratory function. They suggested that this could be caused by a temporary entrapment of the phrenic nerve (i.e. the nerve which supplies the diaphragm). This entrapment decreases neural activity, and ultimately weakens the diaphragm.[3]

Hodges et al[6][7] deduced that altered diaphragm function leads to core muscle instability, which can result in other systemic and musculoskeletal disorders, including spinal instability.

A FHP has an impact on respiratory biomechanics.[8] It results in an expansion of the upper thorax and contraction of the lower thorax. These changes decrease respiratory function.[4]

For the diaphragm of patients with a FHP to be more effective during breathing, we need to:[9]

  1. Restore the normal length-tension relationship
  2. Improve mobility and expansion in the chest wall
  3. Relieve the load on accessory respiratory muscles in the neck[9]

Watch this 6 minute video on how to measure and correct FHP.

Kyphotic Posture[edit | edit source]

Osteoporotic kyphosis in elderly women

Kyphosis is defined as: "an increase in the forward curvature of the spine that is seen along the sagittal plane".[10]

It can be caused by torticollis (i.e. when the neck twists to one side[3]) and FHP leading to the development of a secondary thoracic curve to compensate for the flattening of the cervical spine curve. Altered cervicothoracic mobility impairs normal breathing mechanics by reducing diaphragm mobility and strength.[3][11]

There is approximation of the ribs and pelvis in individuals who are slumped in a kyphotic posture. This approximation can increase intra-abdominal pressure, which affects diaphragmatic movement.[3] This can lead to:[3]

  1. Reduced lung capacity
  2. Reduced inspiratory flow [12]
  3. Decreased forced vital capacity[13]

Watch this 1 minute video on Kyphosis symptoms.

Respiratory function should, therefore, be assessed in patients presenting with postures such as FHP and torticollis.[3] Zafar et al.[3] recommend that clinicians use the SNIP tool (Sniff Nasal Inspiratory Pressure)[14] to assess respiratory function as it is a simple, easy to use method to screen patients who have postural dysfunction.[3]

The below 4 minute video shows how to use a SNIP tool.


Posture in an ICU Bed[edit | edit source]

Pillows are often placed under patients' heads and knees in ICU settings to make them comfortable in bed. However, this positioning causes them to lie in a 'hammock' position, which reduces the ability of the diaphragm to function optimally.[2]

Poor ICU positioning results in:[2]

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

The consequences of this include:[2]

  • Anterior neck muscle tightness
  • Cervical extensor muscle weakness
  • Diaphragmatic weakness

Other Factors to Consider[edit | edit source]

The diaphragm influences:[2]

  1. Oesophageal function
  2. Digestive function
    • Peristaltic movements, massaging of the abdominal contents
  3. Vascular function, such as blood pressure
  4. Immune system
    • The diaphragm helps with immunity because it creates "fresh flow"[2] and assists with the absorption of nutrients and vitamins

More information on the roles of the diaphragm is available here.

References[edit | edit source]

  1. Safavi S, Arthofer C, Cooper A, Harkin JW, Prayle AP, Sovani MP, Bolton CE, Gowland PA, Hall IP. Assessing the impact of posture on diaphragm morphology and function using an open upright MRI system-A pilot study. Eur J Radiol. 2020 Sep;130:109196.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Pandya R. The Effect of Posture on the Diaphragm Course. Plus , 2021.
  3. 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 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.
  4. 4.0 4.1 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.
  5. 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.
  6. 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.
  7. Hodges PW, Butler JE, McKenzie DK, Gandevia SC. Contraction of the human diaphragm during rapid postural adjustments. J Physiol. 1997;505 ( Pt 2)(Pt 2):539-48.
  8. 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.
  9. 9.0 9.1 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.
  10. Lam JC, Mukhdomi T. Kyphosis. [Updated 2021 Aug 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from:
  11. Chaitow L. Functional movement and breathing dysfunction. Journal of bodywork and movement therapies. 2016 Jul 1;20(3):455-6.
  12. 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.
  13. 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.
  14. 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.
  15. ALS Centrum Nederland. SNIP (Sniff nasal inspiratory pressure). Available from: [last accessed 3/12/2021]