Effects of posture on the thickness of transversus abdominis in pain-free subjects

doi:10.1016/j.math.2009.02.008

Manual Therapy

Volume 14, Issue 6, December 2009, Pages 679-684

https://doi.org/10.1016/j.math.2009.02.008 Get rights and content

Abstract

The role of transversus abdominis (TrA) on spinal stability may be important in low back pain (LBP). To date, there have not been any investigations into the influence of lumbo-pelvic neutral posture on TrA activity. The present study therefore examines whether posture influences TrA thickness. A normative within-subjects single-group study was carried out. Twenty healthy adults were recruited and taught five postures: (1) supine lying; (2) erect sitting (lumbo-pelvic neutral); (3) slouched sitting; (4) erect standing (lumbo-pelvic neutral); (5) sway-back standing. In each position, TrA thickness was measured (as an indirect measure of muscle activity) using ultrasound. In erect standing, TrA (mean TrA thickness: 4.63 ± 1.35 mm) was significantly thicker than in sway-back standing (mean TrA thickness: 3.32 ± 0.95 mm) (p = 00001). Similarly, in erect sitting TrA (mean thickness = 4.30 mm ± 1.58 mm) was found to be significantly thicker than in slouched sitting (mean thickness = 3.46 mm ± 1.13 mm) (p = 0002). In conclusion, lumbo-pelvic neutral postures may have a positive influence on spinal stability compared to equivalent poor postures (slouched sitting and sway-back standing) through the recruitment of TrA. Therefore, posture may be important for rehabilitation in patients with LBP.

Introduction

There has been much recent interest in the stability of the lumbar spine and its relation to low back pain (LBP; van Dieen et al., 2003, Hodges, 2003, Silfies et al., 2005). Transversus abdominis (TrA) has been of particular interest to many physiotherapists as a core stability muscle due to its anatomy (O'Sullivan, 2000, Hodges, 2003, Golby et al., 2006). A delayed muscular response of TrA has been found in patients with a history of LBP (Hodges and Richardson, 1996, Hodges and Richardson, 1998, Ferreira et al., 2004), but it is still not clear if this delayed response is a predisposing factor to LBP or is a consequence of LBP (McGill et al., 2003, Hodges and Moseley, 2003).

In a review on posture by Raine and Twomey (1994), it was concluded that there are still controversies and little evidence supporting claims on the benefits of ideal posture or the suggestion that poor posture will lead to musculoskeletal pain. However, in a more recent systematic review, Prins et al. (2008) concluded that musculoskeletal pain may be influenced by sitting posture in children and adolescents. Moreover, a correlation has been observed between spinal posture and LBP (O'Sullivan et al., 2006). There is also an increased risk of LBP in people who have sedentary jobs, with symptoms increasing when sitting for long periods of time (Pope et al., 2002). In a study by Yip et al. (2008), cervical posture was correlated to cervical disability and pain.

The influence of lumbar stability on poor posture versus upright posture has also been studied. It has been reported that there is a significant decrease in activity of the internal oblique (IO) and multifidus muscles in poor sitting and standing postures (Snijders et al., 1998, O'Sullivan et al., 2002, O'Sullivan et al., 2007). In these studies however, the activity of TrA was not measured. The effect of sitting postures on TrA has been studied by Ainscough-Potts et al. (2006), but a lumbo-pelvic neutral spine appeared not to be controlled.

Deep needle electromyography (EMG) is an invasive technique which has resulted in alternative methods of measuring muscle activity. There is now growing evidence of real-time ultrasound as a valid tool to measure muscle thickness, with changes in thickness shown to be correlated to changes in muscle activity at lower levels of maximal voluntary contraction (McMeeken et al., 2004, Hodges et al., 2003a).

The purpose of this study is to use ultrasound to examine changes in thickness of TrA in slouched sitting and sway standing, which are commonly adopted poor standing and sitting postures (Arnold et al., 2000, O'Sullivan et al., 2006), and compare these to erect lumbo-pevic neutral standing and sitting positions.

Section snippets

Subjects

Following ethical approval, by University College London's Committee on the ethics of non-NHS human research, consent was obtained from 20 healthy subjects (10 male and 10 female) with a mean age of 29 years (range 20–51 years). Subjects were excluded if there was a history of abdominal surgery, a history of LBP within the last two years, or a spinal deformity such as scoliosis. Subjects were also excluded if they were pregnant (Snijders et al., 1995).

Procedure

In each subject, the TrA muscle was imaged

Results

The mean TrA thickness for each of the five positions is shown in Fig. 3.

Discussion

The present study was an investigation into the changes in TrA thickness in commonly adopted poor postures (sway-back standing and slouched sitting) compared to equivalent neutral spine postures. The results show a significant thickening of TrA in both lumbo-pelvic neutral erect standing and sitting postures compared to sway-back standing and slouched sitting.

TrA thickness has been shown to be correlated with muscular activity (Hodges et al., 2003a, McMeeken et al., 2004). Therefore, the

Conclusion

In both erect lumbo-pelvic neutral standing and sitting postures there was an increase in TrA thickness compared to sway-back standing or slouched sitting, respectively. Should it be accepted that the observed changes in thickness represent an increase in muscular activity, these results support the evidence of TrA as a postural muscle, possibly assisting in the provision of stability to the spine. The present research also suggests that ‘good’ posture may influence the recruitment of TrA.

Acknowledgments

The assistance of Professor Bruce Lynn is most gratefully acknowledged and also, many thanks to Dr Iain Beith for his advice.

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Original ArticleEffects of posture on the thickness of transversus abdominis in pain-free subjects

Abstract

Introduction

Section snippets

Subjects

Procedure

Results

Discussion

Conclusion

Acknowledgments

Manual Therapy

Journal of Electromyography and Kinesiology

Orthopedic Clinics of North America

Journal of Electromyography and Kinesiology

Journal of Electromyography and Kinesiology

Clinical Biomechanics

Manual Therapy

Manual Therapy

Manual Therapy

Australian Journal of Physiotherapy

Clinical Biomechanics

Clinical Biomechanics

The reliability of five clinical postural alignment measures for women with osteoporosis

Physiotherapy Canada

Surgical anatomy of the aponeurotic expansions of the anterior abdominal wall

Annals of the Royal College of Surgeons of England

Changes in thickness of the left and right human abdominal muscles in standing and lying

Journal of Physiology Proceedings

Observations on intra-abdominal pressure and patterns of abdominal intra muscular activity in man

Acta Physiologica Scandinavica

Changes in recruitment of the abdominal muscles in people with low back pain: ultrasound measurement of muscle activity

Spine

A randomized controlled trial investigating the efficiency of musculoskeletal physiotherapy on chronic low back pain disorder

Spine

Long-term effects of specific stabilizing exercises for first-episode low back pain

Spine

Inefficient muscular stabilization of the lumbar spine associated with back pain: a motor control evaluation of transverus abdominis

Spine

Relationship between limb movement speed and associated contraction of the trunk muscles

Ergonomics

Original Article
Effects of posture on the thickness of transversus abdominis in pain-free subjects