An MRI Investigation Into the Function of the Transversus... : Spine (original) (raw)

Diagnostics

An MRI Investigation Into the Function of the Transversus Abdominis Muscle During “Drawing-In” of the Abdominal Wall

Hides, Julie PhD*; Wilson, Stephen PhD†; Stanton, Warren PhD*; McMahon, Shaun PhD‡; Keto, Heidi BPhty*; McMahon, Katie PhD§; Bryant, Martina B App Sc§; Richardson, Carolyn PhD*

From the *School of Health and Rehabilitation Sciences (Division of Physiotherapy), †School of IT and Electrical Engineering, and §Centre for Magnetic Resonance Imaging, University of Queensland, Brisbane, Australia; and ‡Commonwealth Bank Cricket Academy, Brisbane, Australia.

Acknowledgment date: February 11, 2005. First revision date: May 25, 2005. Second revision date: July 28, 2005. Acceptance date: August 2, 2005.

Supported by Cricket Australia Sports Science Medicine Research Program.

The manuscript submitted does not contain information about medical device(s)/drug(s).

Other funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

Address correspondence and reprint requests to Julie Hides, PhD, Division of Physiotherapy, School of Health and Rehabilitation Sciences, University of Queensland, Brisbane, Australia, 4072. E-mail: [email protected]

Study Design.

An operator blinded dual modality trial of measurement of the abdominal muscles during “drawing-in” of the abdominal wall.

Objectives.

To investigate, using magnetic resonance imaging (MRI), the function of the transversus abdominis muscle bilaterally during a drawing-in of the abdominal wall. 2) To validate the use of real-time ultrasound imaging as a measure of the deep abdominal muscle during a drawing-in of the abdominal wall.

Summary of Background Data.

Previous research has implicated the deep abdominal muscle, transversus abdominis, in the support and protection of the spine and provided evidence that training this muscle is important in the rehabilitation of low back pain. One of the most important actions of the transversus abdominis is to “draw-in” the abdominal wall, and this action has been shown to stiffen the sacroiliac joints. It is hypothesized that in response to a draw in, the transversus abdominis muscle forms a deep musculofascial “corset” and that MRI could be used to view this corset and verify its mechanism of action on the lumbopelvic region.

Methods.

Thirteen healthy asymptomatic male elite cricket players aged 21.3 ± 2.1 years were imaged using MRI and ultrasound imaging as they drew in their abdominal walls. Measurements of the thickness of the transversus abdominis and internal oblique muscles and the slide of the anterior abdominal fascia were measured using both MRI and ultrasound. Measurement of the whole abdominal cross-sectional area (CSA) was conducted using MRI.

Results.

Results of the MRI demonstrated that, as a result of draw-in, there was a significant increase in thickness of the transversus abdominis (P < 0.001) and the internal oblique muscles (P < 0.001). There was a significant decrease in the CSA of the trunk (P < 0.001). The mean slide (±SD) of the anterior abdominal fascia was1.54 ± 0.38 cm for the left side and 1.48 ± 0.35 cm for the right side. Ultrasound measurements of muscle thickness of both transversus abdominis and the internal oblique, as well as fascial slide, correlated with measures obtained using MRI (interclass correlations from 0.78 to 0.95).

Conclusions.

The MRI results demonstrated that during a drawing-in action, the transversus abdominis contracts bilaterally to form a musculofascial band that appears to tighten (like a corset) and most likely improves the stabilization of the lumbopelvic region. Real-time ultrasound imaging can also be used to measure changes in the transversus abdominis during the draw-in maneuver.