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Thoughts about Transversus Abdominis

21st November 2011

By Kari Niemi

Kinetic Control Accredited Tutor Finland

Transversus Abdominis (TrA) is well-known muscle for every physiotherapists. I think there is still some unclear understanding or misinterpretation regarding Transversus Abdominis. Below there are some issues about normal function of Transversus Abdominis and what happens to its function with pain. Also there are ideas about how we can retrain and recover Transversus Abdominis function.

-       Transversus Abdominis controls excessive intersegmental displacement (translation) in all postures and movements

-       Transversus Abdominis activates  prior to the initiation of all movements (feedforward)

-       Patients with low back pain have TrA timing delay (feedforward failure)

-       This timing delay is only present at the initiation of a functional movement or change in posture

-       This timing delay at the initiation of movement is the only consistent measured impairment in TrA related to back pain

-       Transversus Abdominis is always active while moving

-       However, during movement TrA is active

-       Although pain may go away, the Transversus Abdominis dysfunction can still persist and that may predispose to next pain episode (insidious recurrence)

-       TrA thickness (or a change in TrA thickness is not related to back pain)

-       You have to stop breathing to get any significant atrophy in TrA

-       There is no advantage in trying to strengthen or stretch TrA for the management of back pain

-       It is not appropriate just to measure the amount of EMG activity of TrA in a patient with low back pain (more muscle activity and force is not the answer)

-       The answer lies in correcting the timing delay! The timing delay is related to the threshold of automatic activation as you initiate a movement

-       Assessing the quality of voluntary low threshold recruitment efficiency is a way of evaluating change in the activation threshold

-       Measurement studies have demonstrated that cognitive, non-functional, low threshold motor control retraining, can more effectively recover the timing delay in the short term. (Functional exercises or trunk muscles co-contraction exercises do not recover the timing delay in any measurement studies)

-       Specific motor control retraining can reduce symptoms and recurrence of low back pain

-       Corrective changes of Transversus Abdominis motor control can be retained in at least six months with specific motor control retraining strategies

References

Hodges PW, Richardson CA 1996. Inefficient muscular stabilization of the lumbar spine associated with low back pain. A motor control evaluation of transversus abdominis. Spine, Nov 15;21(22):2640-50

Hodges PW, Richardson CA 1997. Contraction of the abdominal muscles associated with movement of the lower limb. Phys Ther, Feb;77(2):132-42

Hodges PW, Richardson CA 1997. Feedforward contraction of transversus abdominis is not influenced by the direction of arm movement. EXP Brain Res, Apr;114(2):362-70

Tsao H, Hodges PW 2007. Immediate changes in feedforward postural adjustments following voluntary motor training. Exp Brain Res, Aug;181(4):537-46

Tsao H, Hodges PW 2008. Persistence of improvements in postural strategies following motor control training in people with recurrent low back pain. J Electromyogr Kinesiol, Aug;18(4):559-6

Tsao H, Galea MP 2008. Reorganization of the motor cortex is associated with postural control deficits in recurrent low back pain. Brain Aug;131(Pt 8):2161-71

Hall L, Tsao H, MacDonald D, Coppieters M, Hodges PW 2009. Immediate effects of co-contraction training on motor control of the trunk muscles in people with recurrent low back pain. J Electromyogr Kinesiol, Oct;19(5):763-73

 

Comment from Mark Comerford

For those of you who find the application of Tissue Doppler Imaging (TDI) with ultrasound interesting I would recommend reading 5 journal articles. As usual, the devil is in the detail, so read the methodology and results (not just the abstract):

1. Reliability of rehabilitative ultrasound imaging of the transversus abdominis and lumbar multifidus muscles. Koppenhaver SL, Hebert JJ, Parent EC, Fritz JM. Aust J Physiother. 2009;55(3):153-69.

2. A new method for the noninvasive determination of abdominal muscle feedforward activity based on tissue velocity information from tissue Doppler imaging. Mannion AF, Pulkovski N, Schenk P, Hodges PW, Gerber H, Loupas T, Gorelick M, Sprott H. J Appl Physiol. 2008 Apr;104(4):1192-201. Epub 2008 Jan 10.

3. Rehabilitative ultrasound imaging of the abdominal muscles. Teyhen DS, Gill NW, Whittaker JL, Henry SM, Hides JA, Hodges P. J Orthop Sports Phys Ther. 2007 Aug;37(8):450-66.

4. Tissue Doppler imaging for detecting onset of muscle activity. Pulkovski N, Schenk P, Maffiuletti NA, Mannion AF. Muscle Nerve. 2008 May;37(5):638-49.

5. Ultrasound assessment of transversus abdominis muscle contraction ratio during abdominal hollowing: a useful tool to distinguish between patients with chronic low back pain and healthy controls? Pulkovski N, Mannion AF, Caporaso F, Toma V, Gubler D, Helbling D, Sprott H. Eur Spine J. 2011 Mar 31

Firstly,all 5 papers agree that fine wire EMG is the ‘gold standard’ for timing measures of the onset of muscle activation. Ultrasound TDI is being evaluated as an alternative less invasive method of measurement.

There are some issues with TDI. Pulkovski et al 2008 stated that TDI is unable to distinguish between the onsets of TrA, IO and the EO muscles, but can measure the onset of first activation of the abdominal muscle group. They determined that measurement of TDI inital onset was on average 20ms (+/- 30ms SD) later than the onset of fine wire EMG recordings.

The systematic review by Koppenhver et al 2009, claims that TDI and M mode US generally only have partial validity for measuring ther timing of muscle activation compared to EMG and in both methods were consistently later than EMG to determine the onset of activation.

When the timing delays in back pain subjects is reliable (but measured in the ranfge of +/- 40ms) the consistent delay in the TDI measurement (thought to be either due to movement artifact or an electromechanixal delay) may have some significant issues with interpretation.



Comment from Kari Niemi

Ultrasound Tissue Doppler Imaging is not as reliable tool to measure TrA timing delay (feedforward).

Direct quotation from the article in question: “In the patient group, the data from 1090/4046 (27%) test trials had to be disregarded due to poor US or EMG quality, technical problems with the switch, difficulties inaccurately determining the onset of activity, or “out of range” onsets (see earlier); the corresponding figure for the control group was 986/3941 (25%) data sets.”
So they had to abandon quite many results.

Kind Regards

Kari Niemi

 

Keywords: Review 2011