Different Ways to Balance the Spine: Subtle Changes in Sagittal Spinal Curves Affect Regional Muscle Activity

Centre of Clinical Research Excellence in Spinal Pain, Injury and Health, The University of Queensland, School of Health and Rehabilitation Sciences, Brisbane, Australia.
Spine (Impact Factor: 2.3). 03/2009; 34(6):E208-14. DOI: 10.1097/BRS.0b013e3181908ead
Source: PubMed


Exploratory study of regional muscle activity in different postures.
To detail the relationship between spinal curves and regional muscle activity.
Sagittal balanced spinal posture (C7 above S1 in the sagittal plane) is a goal for spinal surgery and conservative ergonomics. Three combinations of thoracolumbar and lumbar spinal curves can be considered sagittal balanced postures: (i) flat-at both regions, (ii) long lordosis-lordotic at both regions, and (iii) short lordosis-thoracic kyphosis and lumbar lordosis. This study compares regional muscle activity between these 3 sagittal balanced postures in sitting, as well as a slump posture.
Fine-wire electromyography (EMG) electrodes were inserted into the lumbar multifidus (deep and superficial), iliocostalis (lateral and medial), longissimus thoracis, and transversus abdominis in 14 healthy male volunteers. Fine-wire or surface EMG electrodes were also used to record activity of the obliquus internus, obliquus externus, and rectus abdominis muscles. Root mean square EMG amplitude in the flat, long lordosis, short lordosis, and slump sitting postures were normalized to maximal voluntary contraction, and also to the peak activity across the sitting postures. Muscle activity was compared between postures with a linear mixed model analysis.
Of the extensor muscles, it was most notable that activity of the deep and superficial fibers of lumbar multifidus increased incrementally in the 3 sagittal balanced postures; flat, long lordosis, and short lordosis (P < 0.05). Of the abdominal muscles, obliquus internus was more active in short lordosis than the other postures (P < 0.05). Comparing the sagittal balanced postures, the flat posture showed the least muscle activity (similar to the slump posture at most muscles examined).
Discrete combinations of muscle activity supported the 3 different sagittal balanced postures in sitting, providing new detail for surgeons, researchers, and therapists to distinguish between different sagittal balanced postures.

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Available from: Andrew P Claus, Oct 10, 2015
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    • "t for differences in STS coordination between HU and AT ? Throughout the STS movement , postural tone must sup - port the mass of the upper body and prevent it from collapsing against gravity . As the axial musculature is highly complex and redundant , this postural support can be achieved in different ways , with differing spatial distributions ( Claus et al . 2009 ; O &apos; Sullivan et al . 2006 ) and different dynamic control ( Caccia - tore et al . 2011a ; Gurfinkel et al . 2006 ) . The specific way this support is achieved creates a stiffness distribution across the body or " postural frame . " This may not be localized to the portion of the body being supported , but could extend to more dis"
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    • "Six pairs of surface electrodes as part of the Red Dot monitoring electrode 2223 (3M Health Care, Borken, Germany) were attached while a subject stood relaxed with feet 10 cm apart on a flat surface. One pair of electrodes was positioned over the MF muscle (2 cm lateral to the spinous process of L4) [21], one pair over the lumbar erector spinae (5 cm lateral to the L2 spinous process) [22], one pair over the thoracic erector spinae (TES; 2 to 4 cm lateral to the T12 spinous processes) [23], one pair over the EO (inferior to the rib angle aligned inferomedially toward the pubis) [24], one pair over the IO (medial to anterior superior iliac spine aligned inferomedially toward the pubis) [24], and one pair over the RA (adjacent to the umbilicus) [24] (Fig. 4). "
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