The Role of the Diaphragm in Trunk Stability

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

Overview on Muscle systems[edit | edit source]

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 Transversus Abdominis, Multifidi, Internal Oblique, deep Transversospinalis, and the pelvic floor muscles.

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

Key global muscles include Erector Spinae, External Oblique, Rectus Abdominis muscles, and Quadratus Lumborum.

Diaphragm: Balance, Gait and Trunk Stability[edit | edit source]

  • The diaphragm plays a big role as a trunk stabilizer to enhance balance and walking[1] in conjunction with the abdominal muscles and paraspinal muscles.[2]
  • The diaphragm also plays a role in respiration and trunk stability by controlling intra-abdominal pressure and reducing the stress on the spine through cooperative action with the abdominal and pelvic floor muscles.[3]

Core Stabilizer[edit | edit source]

Diaphragm cylinder.png

The diaphragm, the multifidus muscle, the transverse muscle of the abdomen, and the pelvic floor muscles, act as one unit at the centre of functional kinetic chains. It has been noted that the co-contraction of the abdominal muscles and the diaphragm increases intra-abdominal pressure, fixes the trunk, and reduces the stress on the spine, especially the lumbar region.[4]

  • Muscle of Abdominal Straining

The contraction of the diaphragm will assist in the contraction of the muscles of the anterior abdominal wall in raising the intra-abdominal pressure during normal processes like micturition, defecation, vomiting and parturition (childbirth).

  • Weightlifting Muscle

When a person takes and holds a deep breath, the diaphragm will assist the muscles of the anterior abdominal wall to raise the intra-abdominal pressure.[5] This manoeuvre is also known as the Valsalva manoeuvre and is used to augment heart murmurs and classify them as clinically right-sided or left-sided.[6]

Trunk stability[edit | edit source]

  • 2 Types of Spinal Instability:
    1. Gross Instability: obvious radiographic displacement of the vertebra associated with neurologic deficit and deformity.
    2. Functional/Clinical Instability: "Clinical instability as 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“[7]
  • Core strength provides proximal trunk stability for distal mobility. Hence most of our exercises will focus on mobility of extremities along with core/ lumbar stabilization with deep breathing techniques.[8]
  • 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)[9]

Thoracoabdominal Pump[edit | edit source]

  • When people breathe in, the diaphragm descends, which decreases the intrathoracic pressure and improves the intra-abdominal pressure. This compresses the blood in the Inferior Vena Cava (IVC) and forces it upward into the right atrium to fill the heart. When abdominal lymph vessels are also compressed, its passage upward within the thoracic duct is aided by the negative intrathoracic pressure. Furthermore, valves in the thoracic duct prevent the backflow of the lymph in the thoracic duct.[10] [11]

References[edit | edit source]

  1. 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.
  2. Wilhelm M. The Effect of Low Back Pain History on Multifidus Co-contraction During Common Lumbosacral Voluntary Stabilizing Contractions (Doctoral dissertation).
  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. Michael S, Erik S, Udo S, Edward L. Atlas of Anatomy: General Anatomy and the Musculoskeletal System.
  5. Rasheed H, Ahmad I, Javed MA, Rashid J, Javeed RS. Effects of Diaphragmatic Breathing Maneuver and Abdominal Drawing-in Maneuver on trunk stability in stroke patients. Physical & Occupational Therapy In Geriatrics. 2021 Jan 2;39(1):1-0.
  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. Panjabi MM. Clinical spinal instability and low back pain. Journal of electromyography and kinesiology. 2003 Aug 1;13(4):371-9.
  8. 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.
  9. 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).
  10. Bains KN, Kashyap S, Lappin SL. Anatomy, Thorax, Diaphragm. StatPearls [Internet]. 2021 Jul 26.
  11. McCool FD, Manzoor K, Minami T. Disorders of the diaphragm. Clinics in chest medicine. 2018 Jun 1;39(2):345-60.