Anterior Oblique Subsystem (AOS)

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



Anterior Oblique Subsystem (AOS) — 38 Comments

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  7. Hi Brent, could you talk about your source for the word “subsystems”, and the difference btw/crossover of subsystems and myofascial slings. Thank you!

    • I first heard of subsystems through NASM… I do not believe there is any difference between subsystems and myofascial slings. Any references you have would be greatly appreciated, the research overall seems very scarce. However, the concept does a wonderful job of explaining activity and function of core musculature.

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  10. Hi brent,
    I read the series of your articles that deals with “Core Subsystems”.
    Good articles and great methodological connection between the theory and practice.

    I have an Msc degree in Exercise and Sport Science, i know and read most of the the literature that published from the figures in that knowledge area (core):
    – the australian team – Hodges, Hides and Richardson.
    – the candian group – Stu Mcgill and his colleagues and students.
    – Andry Vleeming and his group from the netherlands.
    – Thomas myers (with continue his mentors) – anatomy trains and/or myofascial meridians/slings.

    The approach that you present here is very interesting, it seems (correct me if im wrong) that you do a synthesis of your wide knowledge with the basic idea of the subsystems (that name and approach is new to me).
    I will be happy for your Proffesional comment and more happy if you write some references that you rely on them, because i wand to read and learn 😉

    Thanks in advance
    (sorry about the poor english)


    • Hey Roy,
      You are absolutely right… I am relying on my knowledge base, my theoretical models of postural dysfunction, and previous experience and should put some more effort into a lit review. My first introduction to the subsystems was via the NASM (National Academy of Sports Medicine) texts. Part of the reason why this blog exists is for me to “vet” my new ideas and continue refining my writing before compiling a formal text. Comments like yours are exactly what I need to ensure I continue to grow and deliver the product everyone wishes to see.
      The Core Subsystems articles have become some of my most popular articles to my great surprise. It is obvious that I need to increase my efforts to refine these writings.
      Thanks again,

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  15. I read this article and it was very well written. Because of attending your workshops, I was able to pretty much comprehend everything. Thank you for everything.

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  27. very informative and usefull info.
    my case is a medical problem I have had a number of years.
    I have ataxia(or so they say)but is it?i have been having differing opinions as to my problem over a number of years.
    at one time I was examined in a hospital by neurologists,professors,doctors phisios,chiropractors,muscular skeletal specialists and the like.
    they have given me every possible medical tests(x ray,mri scan of brain and spine,blood tests for every possible medical condition and have all come back ok.
    there is difference of opinion between even top neurologists but I believe it is a muscle weakness problem.
    do you have a clinic which people like myself can attend in this country because bupa and the nhs are unable to sort out a problem like mine.

  28. Brent,

    I’ve been following you for a while and your articles have really helped me with LPHCD. Glutes are firing again and other muscles are starting to feel freer which is amazing. THANK YOU!

    There is one thing I can’t figure out though. I have a bit of a twisting dysfunction, most likely due to SIJD. The rectus is overactive on the right and I can’t seem to get it firing on the left side (specifically in the lowest portion of the muscle). You mention in this article that it is not possible to isolate one side of the rectus, so what should I do? All exercises (chop and lift, oblique curls, etc) only seem to recruit the right side and I sometimes cramp up.

    I’ve read your article on SIJD. I am a massage therapist and it still gave me a bit of a headache but I was able to follow most of it. I believe my dysfunction is on the right side. Do you think that if I follow the corrective exercise routine that this problem will resolve eventually?

    • If the program was going to work, it should have had some effect the first time you tried it.
      It is possible that you have joint dyskinesis that requires manual intervention (pubic symphysis, sacroiliac and lumbar facet dysfunction). You may consider seeing a physical therapist for an in-person evaluation.

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