The Role of the Diaphragm in Trunk Stability

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

Introduction[edit | edit source]

This page looks at role of the diaphragm in trunk stability. This muscle should not be forgotten when working with patients post-mechanical ventilation, or in individuals who have lower back pain, gait or balance dysfunction. This page includes a brief overview of the muscles of respiration, and discusses concepts that are relevant when working to re-educate the diaphragm and enhance core stability.

1. Overview on Muscle systems[edit | edit source]

The local muscle system is comprised of a deep layer of slow-twitch muscles that control intersegmental movements. These muscles respond to changes in posture and extrinsic loads.

Key local muscles include:

The global muscle system involves fast-twitch, long muscles that possess a large lever arm to produce torque and gross movements.

Key global muscles include:

For more information, please see this page: Muscles of Respiration.

2. Important Concepts in Relation to Diaphragm Rehabilitation[edit | edit source]

1. Thoracoabdominal Pump

  • The diaphragm plays an important role in venous return. On inspiration, the diaphragm descends. This movement of the diaphragm increases pressure in the abdominal cavity and decreases pressure in the intrathoracic cavity.[1] Increased pressure in the abdominal cavity leads to compression of the inferior vena cava (IVC), which helps to move blood, against gravity, into the right atrium of the heart.[1][2]
  • The same applies to the abdominal lymph vessels.[1] Negative intrathoracic pressure, caused by the decent of the diaphragm, and compression of the abdominal lymph vessels lead to an upward movement of the lymph. The valves in the thoracic duct prevent the lymph from flowing back down.[3]

2. Valsalva Manoeuvre

  • The Valsalva manoeuvre is defined as forced expiration against a closed glottis.[4] It is associated with an increase in intrathoracic and intra-abdominal pressure.
  • This simple movement is associated with a complex cardiovascular response and other regulatory mechanisms.[4]
    • The primarily aim of these mechanisms is to control arterial blood pressure.[4]
  • Physicians can assess arterial blood pressure and heart rate changes during and after a Valsalva manoeuvre to diagnose or confirm a diagnosis of a range of conditions.[4]
  • Detecting heart murmurs:
    • The Valsalva manoeuvre can also be used clinically to classify heart murmurs as clinically right-sided or left-sided.[1][5][6]
  • For more on this test, please see this page: Valsalva Test.

The Diaphragm's Role in Balance and Gait[edit | edit source]

The diaphragm is primarily a muscle of respiration and it controls how we breathe. However, it also has an important role in stabilising the trunk to enhance balance and walking[7] in conjunction with the abdominal muscles and paraspinal muscles.[8]

The Diaphragm as a Core Stabiliser[edit | edit source]

Diaphragm cylinder.png

The diaphragm, multifidus, transversus abdominis, and the pelvic floor muscles act as one unit at the centre of various functional kinetic chains. It has been noted that the cooperative actions of these muscles controls intra-abdominal pressure, fixes the trunk, and reduces stress on the spine, especially in the lumbar region.[9][10]

Muscle of Abdominal Straining and Weight Lifting[edit | edit source]

Contraction of the diaphragm and the muscles of the anterior abdominal wall leads to an increase in intra-abdominal pressure during normal processes like micturition, defecation, vomiting and parturition (childbirth).[3]

Trunk stability[edit | edit source]

There are two types of spinal instability:[3]

  1. Gross Instability: obvious radiographic displacement of the vertebra associated with neurologic deficit and deformity.
  2. Functional/Clinical Instability: Clinical instability is "the loss of the spine's ability to maintain its patterns of displacement under physiologic loads so there is no initial or additional neurologic deficit, no major deformity, and no incapacitating pain"[11]
  • Core strength provides proximal trunk stability for distal mobility. Hence, most of exercises prescribed by physiotherapists will focus on the mobility of extremities along with core/ lumbar stabilisation and deep breathing techniques.[3][12]
  • Training of the core involves the coordination of both sensory and motor inputs, comprising of:
    • Neuromuscular control
    • Passive structural components (osseous and ligamentous elements)
    • Active mobile components (29 pairs of muscular elements)[13]

More information on the rehabilitation of the diaphragm is available here: Diaphragm Rehabilitation

Additional Resources[edit | edit source]

References[edit | edit source]

  1. ↑ 1.0 1.1 1.2 1.3 Bains KN, Kashyap S, Lappin SL. Anatomy, Thorax, Diaphragm. StatPearls [Internet]. 2021 Jul 26.
  2. ↑ McCool FD, Manzoor K, Minami T. Disorders of the diaphragm. Clinics in chest medicine. 2018 Jun 1;39(2):345-60.
  3. ↑ 3.0 3.1 3.2 3.3 Pandya R. The Role of the Diaphragm in Trunk Stability Course. Plus , 2022.
  4. ↑ 4.0 4.1 4.2 4.3 Pstras L, Thomaseth K, Waniewski J, Balzani I, Bellavere F. The Valsalva manoeuvre: physiology and clinical examples. Acta physiologica. 2016 Jun;217(2):103-19.
  5. ↑ Roy JK, Roy TS, Mukhopadhyay SC. Heart sound: Detection and analytical approach towards diseases. InModern Sensing Technologies 2019 (pp. 103-145). Springer, Cham.
  6. ↑ Wirth K, Hartmann H, Mickel C, Szilvas E, Keiner M, Sander A. Core stability in athletes: a critical analysis of current guidelines. Sports medicine. 2017 Mar;47(3):401-14.
  7. ↑ Kocjan J, Gzik-Zroska B, Nowakowska K, Burkacki M, Suchoń S, Michnik R, Czyżewski D, Adamek M. Impact of diaphragm function parameters on balance maintenance. Plos one. 2018 Dec 28;13(12):e0208697.
  8. ↑ Wilhelm M. The Effect of Low Back Pain History on Multifidus Co-contraction During Common Lumbosacral Voluntary Stabilizing Contractions (Doctoral dissertation).
  9. ↑ 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.
  10. ↑ Michael S, Erik S, Udo S, Edward L. Atlas of Anatomy: General Anatomy and the Musculoskeletal System.
  11. ↑ Panjabi MM. Clinical spinal instability and low back pain. Journal of electromyography and kinesiology. 2003 Aug 1;13(4):371-9.
  12. ↑ Kim E, Lee H. The effects of deep abdominal muscle strengthening exercises on respiratory function and lumbar stability. Journal of physical therapy science. 2013 Jun 25;25(6):663-5.
  13. ↑ Walters S, GradCert B. Investigation into intra-abdominal pressure and neuromuscular activation to increase force production in traditional martial arts practitioners (Doctoral dissertation, University of Southern Queensland).
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