Anterior Oblique Subsystem Integration

By Brent Brookbush MS, PES, CES, CSCS, ACSM H/FS

The Anterior Oblique Subsystem (AOS) is comprised of:

  • External Obliques
  • Abdominal Fascia/Linea Alba
  • Contralateral Anterior Adductors
  • Internal Obliques
  • Rectus Abdominis
  • Note: The internal obliques and rectus abdominis are not traditionally viewed as muscles of the AOS.  However, based on my considerations of anatomy, function, and available research, and observations in practice, adding these muscles to this subsystem adds congruence to our understanding of muscular synergies, motor behavior, and predictive models of movement impairment.

Function (Brief):

Stabilization of the anterior kinetic chain (including the joints of the pubic symphysis, hip and lumbar spine), transfer of force between lower and upper extremities, integrated (whole body) pushing movements, “turning-in” of the kinetic chain, eccentric deceleration of total-body supination.

Functional Arthrokinematics:
The Anterior Oblique Subsystem (AOS) is an important stabilizer of the anterior kinetic chain.  This subsystem has little direct effect on joint arthrokinematics (when compared to the Posterior Oblique Subsystem (POS) and the sacroiliac joint); however, it is indirectly involved in stabilization of the lumbar spine, thoracic spine, rib cage, pubic symphysis, and hip joint.

The AOS is responsible for eccentric deceleration of rotation and extension of the lumbar and thoracic spine – a movement pattern that may lead to facet joint and posterior disk compression and has been indicated in lumbar spine injury.  The AOS is also involved in eccentric deceleration of an anterior pelvic tilt, especially during standing, pushing motions.  As an anterior pelvic tilt includes lumbar spine extension, sacroiliac joint (SIJ) motion, and if not symmetrical may include rotation; any dyskinesis of the SI