Physical Therapy Blog

What Research says about Abdominal Bracing Vs. Transverse Abdominus Activation and Why it is Important in Recovery from Various Lumbosacral Injuries!

There has been some argument in research journals as to whether or not isolated activation of the transverse abdominus (TA) muscle is more effective than abdominal bracing (AB) which includes all of the abdominal muscles, in improving lumbopelvic stability. 

A study by Grenier and McGill (1) compared isolated TA versus AB on spine stability via EMG and spine kinematics.  They concluded that AB improved stability in the lumbar spine by 32% with a 15% increase in lumbar compression versus isolated TA activation alone, which only contributed .14% to stability and .1% decrease in compression.

Another study by Richardson, et al. (2) supported isolated TA activation instead of AB for increasing sacroiliac joint stability.  Their study used Doppler imaging to record sacroiliac joint laxity in combination with EMG and ultrasound to record muscle activation.  They concluded from their findings that TA activation alone increased sacroiliac joint stability as compared to general abdominal bracing.

Finally, an MRI study by Hides, et al. (3) looked at the TA muscle during "drawing-in" of the abdominal wall.  They hypothesized that the drawing in action of the abdominal wall is important in lumbosacral injury rehabilitation because it stiffens the sacroiliac joint.  They also hypothesized that drawing in causes the TA to form a corset and that the MRI could be used to view the corset and verify its effect on the lumbopelvic region.  Results of the MRI and following ultrasound showed increased thickness in TA and the internal obliques during drawing in of the abdominal wall.  They concluded these findings supported their theory that the TA acts like a corset and improves lumbosacral stability during the drawing-in maneuver.  So How Does This Information Affect Patients with Lumbosacral Injuries??

From our observation working with patients experiencing lumbosacral region injuries, it is unlikely that they are able to isolate transverse abdominus alone no matter how many verbal or tactile cues we provide them.  They are most likely activating a combination of abdominal muscles when we are training them to draw in their abdominal wall to increase lumbosacral stability during the rehab exercises we prescribe.  Our goal in the end is to get our patients to use their abdominal muscles automatically, in other words, without thinking about doing so. 

Additionally, looking at abdominal muscle activation is only one piece of each patient's "puzzle" when looking at the myriad of lumbosacral injuries and how each patient presents differently.  Prescribing abdominal bracing exercises is only one part of the variety of treatment strategies that may be needed for each specific patient.  This particular strategy helps allow our patients to return to performing functional and recreational activities without risk for re-injury to the same region. 

References:

1) Grenier SG, McGill SM. Quantification of lumbar stability by using 2 different abdominal activation strategies.  Spine Biomechanics Laboratory, Department of Kinesiology, Faculty of Applied Health Sciences, University of Waterloo, ON, Canada.  Arch Phys Med Rehabil. 2007 Jan;88(1):54-62.

2)  Richardson CA, Snijders CJ, Hides JA, Damen L, Pas MS, Storm J. The relation between the transversus abdominis muscles, sacroiliac joint mechanics, and low back pain.  Spine. 2002 Feb 15;27(4):399-405.

3) Hides J, Wilson S, Stanton W, McMahon S, Keto H, McMahon K, Bryant M, Richardson C. An MRI investigation into the function of the transversus abdominis muscle during "drawing-in" of the abdominal wall.  Division of Physiotherapy, School of Health and Rehabilitation Sciences, University of Queensland, Brisbane, Australia.  Spine. 2006 Mar 15;31(6):E175-8.