Corset hypothesis rebutted - Transversus abdominis does not co-contract in unison prior to rapid arm movements
PainSci summary of Morris 2011?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.
“These findings indicate that training bilateral pre-activation of the transversus abdominis prior to rapid movement is not justified and may potentially be problematic for the production of normal movement patterns.” This significantly undermines a classic theory (see Hodges et al) used to justify an “advanced” approach to core strength training.
original abstract†Abstracts 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.
BACKGROUND: The aim of this paper is to test "corset" model of spinal stability, specifically the hypothesis that feed forward transversus abdominis activity is bilaterally symmetrical and independent of the direction of perturbation to posture due to arm. This study will assess transversus abdominis electromyographical activity bilaterally.
METHODS: Feed forward intramuscular transversus abdominis electromyographical data and reaction forces on the thorax due to the arm movement were collected and processed for 6 healthy subjects during 6 trials of 8 types of arm movements (randomised order). Reciprocal transversus abdominis indices were calculated as the difference between the normalised integrated feed forward transversus abdominis electromyographical data from each side of the trunk.
FINDINGS: The main finding of the study was that the reciprocal transversus abdominis index was significantly related to the axial rotational forces on the thorax due to arm movement (F=109.991, p<0.001). Right arm movements produced clockwise axial rotation forces on the thorax and dominant left transversus abdominis muscle activity.
INTERPRETATION: The consequence of this finding is that feed forward transversus abdominis activity is not bilaterally symmetrical and is not independent of the direction of perturbation to posture due to arm movement. Transversus abdominis forms part of a synergy of muscles contributing to the generation of axial rotation forces in the core that oppose the forces due to arm movement. These findings indicate that training bilateral pre-activation of the transversus abdominis prior to rapid movement is not justified and may potentially be problematic for the production of normal movement patterns.
related content
Morris 2011 is about:
- PS Your Back Is Not Out of Alignment — Debunking the obsession with alignment, posture, and other biomechanical bogeymen as major causes of pain
This page is part of the PainScience BIBLIOGRAPHY, which contains plain language summaries of thousands of scientific papers & others sources. It’s like a highly specialized blog. A few highlights:
- A Bayesian model-averaged meta-analysis of the power pose effect with informed and default priors: the case of felt power. Gronau 2017 Comprehensive Results in Social Psychology.
- Association of Spinal Manipulative Therapy With Clinical Benefit and Harm for Acute Low Back Pain: Systematic Review and Meta-analysis. Paige 2017 JAMA.
- Incidence of Spontaneous Resorption of Lumbar Disc Herniation: A Meta-Analysis. Zhong 2017 Pain Physician.
- How much is too much? (Part 1) International Olympic Committee consensus statement on load in sport and risk of injury. Soligard 2016 Br J Sports Med.
- Chiropractic spinal manipulative therapy for migraine: a three-armed, single-blinded, placebo, randomized controlled trial. Chaibi 2016 Eur J Neurol.