Differential activity of regions of transversus abdominis during trunk rotation

Abstract

The role of the abdominal muscles in trunk rotation is not comprehensively understood. This study investigated the electromyographic (EMG) activity of anatomically distinct regions of the abdominal muscles during trunk rotation in six subjects with no history of spinal pain. Fine-wire electrodes were inserted into the right abdominal wall; upper region of transversus abdominis (TrA), middle region of TrA, obliquus internus abdominis (OI) and obliquus externus abdominis (OE), and lower region of TrA and OI. Surface electrodes were placed over right rectus abdominis (RA). Subjects performed trunk rotation to the left and right in sitting by rotating their pelvis relative to a fixed thorax. EMG activity was recorded in relaxed supine and sitting, and during an isometric hold at end range. TrA was consistently active during trunk rotation, with the recruitment patterns of the upper fascicles opposite to that of the middle and lower fascicles. During left rotation, there was greater activity of the lower and middle regions of contralateral TrA and the lower region of contralateral OI. The upper region of ipsilateral TrA and OE were predominately active during right rotation. In contrast, there was no difference in activity of RA and middle OI between directions (although middle OI was different between directions for all but one subject). This study indicates that TrA is active during trunk rotation, but this activity varies between muscle regions. These normative data will assist in understanding the role of TrA in lumbopelvic control and movement, and the effect of spinal pain on abdominal muscle recruitment.

Changes in Regional Activity of the Psoas Major and Quadratus Lumborum With Voluntary Trunk and Hip Tasks and Different Spinal Curvatures in Sitting

“…24 Of the 9 participants, 2 were excluded from analysis of MVC tasks because 2 of the MVC tasks were not completed.…”

Rehabilitative Ultrasound Imaging of the Abdominal Muscles

“…20,53,76,101,110,[112][113][114] Appreciation of these regional differences assists researchers and clinicians in understanding the influence of these deep muscles on the fascial system and how these differences may pertain to control of the lumbar spine and pelvis. Due to the unique function of the TrA muscle during lumbopelvic loadings, 51,53 the apparent prevalence of changes in control of this muscle in people with lumbopelvic pain, 27,52 and the evidence that changes in this muscle can be identified with RUSI, 27,39 the regional anatomy of this muscle is presented in greater detail.…”

“…The upper horizontally oriented fascicles are thought to assist control of the rib cage via their origins on the lower 6 costal cartilages. 19,110,112 The middle fascicles, which have a slight inferiormedial orientation, attach extensively to the aponeurosis of the TLF, 5,110 while the lower, more medially oriented fascicles arise from the iliac crest and inguinal ligament. 110,112 These morphological differences have implications for the potential contribution of the TrA muscle to lumbopelvic control.…”

“…19,110,112 The middle fascicles, which have a slight inferiormedial orientation, attach extensively to the aponeurosis of the TLF, 5,110 while the lower, more medially oriented fascicles arise from the iliac crest and inguinal ligament. 110,112 These morphological differences have implications for the potential contribution of the TrA muscle to lumbopelvic control. Specifically, bilateral activation of the TrA muscle can contribute via tensioning fascial structures of the lumbar region, including the TLF, 5 via modulation of intra-abdominal pressure (IAP) [45][46][47] and compression of the sacroiliac joint 92 and the inferior rib cage.…”

Observation of Age‐Related Decline in the Performance of the Transverse Abdominis Muscle

“…The TrA in particular has a multifunctional role as it potentially functions as a stabiliser muscle, as well as having a minor role in trunk rotation [3] and respiration [4].…”