Assessment of abdominal muscle function during a simulated unilateral weight-bearing task using ultrasound imaging.
METHODS
Cross-sectional study.


OBJECTIVE
To investigate the function of the transversus abdominis (TrA) and internal oblique (10) muscles bilaterally during a simulated weight-bearing task using ultrasound imaging.


BACKGROUND
An important aspect of neuromuscular control at the lumbopelvic region is stabilization. Biomechanical models have predicted that activation of transversely oriented muscles, such as the TrA and 10 muscles, can stiffen the sacroiliac joints and actively stabilize the pelvis for weight bearing.


METHODS
Nineteen healthy subjects were positioned in supine lying with their right heel against a footplate linked to a force transducer. Each subject performed a static simulated weight-bearing task of the right lower extremity. Ultrasound imaging was used to assess resultant changes in thickness of the 10 and TrA muscles, as well as the lateral slide of the anterior abdominal fascia on each side of the abdomen alternately. Muscle thickness and slide of the fascia were assessed at standardized force levels (0% and 25% of body weight).


RESULTS
Substantial increases (P < .0001) in mean (+/- SD) thickness of the 10 (18.5% +/- 9.7%) and TrA (24.7% +/- 175%) muscles during the weight-bearing task were measured. Lateral movement (slide) of the anterior abdominal fascia of the TrA muscle also occurred (mean +/- SD, 1.3 +/- 2.0 mm; P = .014) with weight bearing. Changes in muscle thickness and amount of slide were similar for the left and right side of the abdomen (P > or = .11).


CONCLUSIONS
The findings are consistent with biomechanical models that predicted symmetrical activation of the deep transversely oriented lumbopelvic muscles in healthy subjects in response to a unilateral functional weight-bearing task. Ultrasound imaging as a measurement tool represents a noninvasive method for measuring abdominal muscle function in functional axial loading.
Hides
Julie A
JA
Division of Physiotherapy, School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Australia. j.hides@shrs.uq.edu.au
Wong
Ian
I
Wilson
Stephen J
SJ
Belavý
Daniel L
DL
Richardson
Carolyn A
CA
D000009:Abdominal Muscles / Q000000981:diagnostic imaging* / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D011793:Queensland; D014463:Ultrasonography; D016474:Weight-Bearing / Q000502:physiology*