EFFECT OF 2 LUMBAR SPINE POSTURES ON TRANSVERSUS ABDOMINIS MUSCLE THICKNESS DURING A VOLUNTARY CONTRACTION IN PEOPLE WITH AND WITHOUT LOW BACK PAIN

Objective: The present study investigated the effect of 2 different lumbar spine postures, neutral and flexed lumbar postures, on transversus abdominis (TrA) muscle function during a voluntary contraction (hollowing and draw-in maneuver) in people with and without low back pain (LBP). Methods: Thirty participants with LBP and 30 healthy participants were recruited for this cross-sectional study. Transversus abdominis muscle function was measured as a change in thickness with ultrasound imaging. Participants performed voluntary TrA contraction in a supine lying position with the lumbar spine in neutral and flexed postures. Data were analyzed using a 2-way (groups, postures) analysis of variance. Results: Lumbar posture influenced TrA function during a voluntary contraction in people with and without LBP. There was a significant main effect of posture (F(1,58) = 16.140, P < .001). Neutral lumbar posture improved participants' ability to recruit TrA in both group (mean difference, 7.5%; 95% confidence interval, 3.8%-11.3%). No significant differences were found between healthy subjects and those with LBP. Conclusions: The results of the present study showed that, in subjects performing a voluntary TrA contraction, the neutral lumbar posture improves the ability to increase change in TrA thickness. This study found no significant difference in TrA thickness change between healthy subjects and those with nonspecific LBP. (J Manipulative Physiol Ther 2011; 34: 164-172)