725: Activation of Regions of Quadratus Lumborum during Functional Tasks: A Preliminary Case Series Study

Topic: Experimental (Non-clinical) Human Studies
Subtopic: Pain Category (ICD-11), Chronic primary musculoskeletal pain, Developing methodology/technology, Physiotherapy, Imaging (e.g. fMRI, PET, MRS)

Background and Aims: Highest prevalence of Quadratus Lumborum (QL) myofascial dysfunction is reported among commonly affected muscles in patients with chronic low back pain (CLBP). Motor adaptation and movement strategy change due to pain or perception of pain has been shown in CLBP. Cadaveric and fine-wire EMG studies suggest distinct anatomical and functional roles of QL fascicles. Specifically, QL anterior (a) and QL posterior (p) lateral (L) region is the location of global iliocostal fibers, whereas the QLp medial (M) region is the location of local iliolumbar fibers. However, fine-wire EMG is invasive and not commonly available in clinical settings. Task-specific activation of distinct QL fascicles has not yet been investigated using ultrasonography. This preliminary in-vivo case series aimed to demonstrate task-specific activation patterns of QL fascicles in healthy participants using ultrasonography, which could lay the foundation to understand the compensation of muscle fibers of QL in patients with low back pain.

Methods: Four healthy participants were assessed in prone and side-lying positions using musculoskeletal ultrasonography. QL fascicles were identified in transverse and longitudinal views. Participants performed five tasks, prone hip hiking, side-lying hip hiking, prone trunk extension, prone contralateral hip extension, and breathing tasks including quiet inhalation and resisted inhalation.

Results: Hip hiking in prone showed activation in the QLa and QLpL region. Hip hiking in sidelying activates both QLa and QLpL and QLpM fascicles. Prone trunk extension showed erector spinae (ES) activation first, followed by smaller QLp activation. The QLpM region contracted in isolation during prone contralateral hip extension (stability task). During quiet inhalation, the QLpM region individually contracted. During inhalation with resistance to the rib cage, both QLpM, QLpL and QLa were activated.

Conclusions: These preliminary findings demonstrated region-specific activation patterns during different tasks for mobility/stability and breathing. The local QLpM region indicated the iliolumbar fascicle playing a role in trunk stability and breathing. The more global QLa and QLpL region indicated the iliocostal fascicles related to tasks for hiking in prone. A higher demand task of hiking in sidelying activated all regions of QL. QLp appeared to be a synergist in trunk extension.

Clinical implication: Dynamic ultrasonography is a tool for the assessment of in-vivo activation of different regions of QL. Further investigation of patients with CLBP could reveal the principle of inhibition of deep local muscles and increased activation of global fibers in QL during pain adaptation.

References: 1. Coelho, D., Barbosa, R., Pavan, A., Oliveira, A., Bevilaqua-Grossi, D., & Defino, H. (2014). Prevalence of myofascial dysfunction in patients with low back pain. Acta Fisiátrica, 21, 71-74. https://doi.org/10.11606/issn.2317-0190.v21i2a103835
2. Phillips S, Mercer S, Bogduk N. Anatomy and biomechanics of quadratus lumborum. Proc Inst Mech Eng H. 2008 Feb;222(2):151-9. doi: 10.1243/09544119JEIM266IPMID: 18441751
3. Hodges, P. W., & Tucker, K. (2011). Moving differently in pain: a new theory to explain the adaptation to pain. Pain, 152(3 Suppl), S90-s98. https://doi.org/10.1016/j.pain.2010.10.020
4. Park RJ, Tsao H, Claus A, Cresswell AG, Hodges PW. Changes in regional activity of the psoas major and quadratus lumborum with voluntary trunk and hip tasks and different spinal curvatures in sitting. J Orthop Sports Phys Ther. 2013 Feb;43(2):74-82. doi: 10.2519/jospt.2013.4292. Epub 2012 Sep 5. PMID: 22960605.
5. Park RJ, Tsao H, Cresswell AG, Hodges PW. Differential activity of regions of the psoas major and quadratus lumborum during submaximal isometric trunk efforts. J Orthop Res. 2012 Feb;30(2):311-8. doi: 10.1002/jor.21499. Epub 2011 Jul 28. PMID: 21800359.
6. Park RJ, Tsao H, Cresswell AG, Hodges PW. Changes in direction-specific activity of psoas major and quadratus lumborum in people with recurring back pain differ between muscle regions and patient groups. J Electromyogr Kinesiol. 2013 Jun;23(3):734-40. doi: 10.1016/j.jelekin.2013.01.010. Epub 2013 Feb 28. PMID: 23453455.
7. Park RJ, Tsao H, Cresswell AG, Hodges PW. Anticipatory postural activity of the deep trunk muscles differs between anatomical regions based on their mechanical advantage. Neuroscience. 2014 Mar 7;261:161-72. doi: 10.1016/j.neuroscience.2013.12.037. Epub 2013 Dec 25. PMID: 24370638.
8. Donnelly, J. M., de las Peñas, C. F., Finnegan, M., & Freeman, J. L. (2019). Travell, Simons & Simons' Myofascial Pain and Dysfunction: The Trigger Point Manual (3rd ed.). Lippincott Williams & Wilkins.

Presenting Author: Sii, Joseph Ern-liang
Submitting Author: Sii Joseph, Ern-liang

Senior Author: Dr. Prof. Wang Shwufen

IASP 2026 Global Year theme of Neuropathic Pain: No

• Wang Shwufen: P.H.D - National Taiwan University