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bibliography*The PainScience Bibliography contains plain language summaries of thousands of scientific papers and others sources, like a specialized blog. This page is about a single scientific paper in the bibliography, Andersson 1996.

EMG activities of the quadratus lumborum and erector spinae muscles during flexion-relaxation and other motor tasks

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Tags: anatomy, muscle, spine, biomechanics, movement, etiology, pro

PainSci summary of Andersson 1996?This page is one of thousands in the PainScience.com bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided at the bottom of the page, as often as possible. ★★★☆☆?3-star ratings are for typical studies with no more (or less) than the usual common problems. Ratings are a highly subjective opinion, and subject to revision at any time. If you think this paper has been incorrectly rated, please let me know.

An EMG study showing that quadratus lumborum is most active in a wide plank position, and curiously activates at the same time the big trunk extensors relax in flexion (flexion-relaxation phenomenon, a reduction or silence of myoelectric activity of the lumbar erector spinae muscle during full trunk flexion). See also McGill et al.

~ Paul Ingraham

original abstractAbstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

OBJECTIVE: The aim of this study was to provide new information on the myoelectrical activation of the quadratus lumborum, the deep lateral and the superficial medial lumbar erector spinae, the psoas, and the iliacus muscles in various motor tasks.

DESIGN: An intramuscular electromyographic study was performed.

BACKGROUND: The contribution of individual deep trunk muscles to the stability of the lumbar spine is relatively unknown in different tasks, including the flexion-relaxation phenomenon.

METHODS: Seven healthy subjects participated. Fine-wire electrodes were inserted with a needle guided by ultrasound.

RESULTS: The highest activity observed for quadratus lumborum and deep lateral erector spinae occurred in ipsilateral trunk flexion in a side-lying position and for superficial medial erector spinae during bilateral leg lift in a prone position. Quadratus lumborum and deep lateral erector spinae were activated when the flexion-relaxation phenomenon was present for superficial medial erector spinae, i.e. when its activity ceased in the latter part of full forward flexion of the trunk, held relaxed and kyphotic.

CONCLUSIONS: In general, the activation of the investigated muscles showed a high degree of task specificity, where activation of a certain muscle was not always predictable from its anatomical arrangement and mechanical advantage.

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