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Intrinsic stabilization subsystem. The role and function of the transverse abdominis, multifidus, pelvic floor, and diaphragm in the stability and control of the lumbar spine, pelvis, and ribcage. Summary of the function, arthrokinematics, integration between individual subsystems, behavior in postural dysfunction, exercise selection for the intrinsic stabilization subsystem (core/TVA), and videos depicting exercises and progressions.

This course describes the intrinsic stabilization subsystem (ISS). This subsystem may also be referred to as intrinsic core muscles, deep core muscles, intrinsic stabilizers, stabilizing system, local stabilizers, lumbar stabilizers, and is related to the terms muscle sling, myofascial sling, myofascial synergy, oblique sling, core subsystem, myofascial lines, myofascial trains, anatomy trains, myofascial meridians, and deep front line. This course covers a detailed analysis of the intrinsic stabilization subsystem (deep core muscles) including anatomy, research, integration techniques and a sample routine.

The Intrinsic Stabilization Subsystem is comprised of:

Pelvic Floor (Levator ani, coccygeus, and associated fascia)

Rotatores, Interspinales & Intertransversarii

Continuous with investing fascia of Diaphragm and Pelvic Floor

Thoracolumbar Fascia (TLF) (anterior and middle layer)

The concepts and techniques described in this course may be particularly beneficial for neuromuscular re-education, coordination, motor pattern integration, whole-body strength, functional strength, and sports performance. Sports medicine professionals (personal trainers, fitness instructors, physical therapists, massage therapists, chiropractors, occupational therapists, athletic trainers, etc.) should consider adding these exercises to their repertoire to improve the outcomes of their integrated exercise programs, sports performance programs, and therapeutic (rehabilitation) interventions.

For additional self-administered joint mobilization techniques check out:

Course Description: Intrinsic Stabilization Subsystem

Intrinsic Stabilization Subsystem Study Guide

Study Guide: Intrinsic Stabilization Subsystem 

Review of Core Subsystems

Introduction

The ISS is comprised of muscles of the lumbar spine and pelvis that do not contribute or contribute very little to motion. The function of this subsystem is to increase intra-abdominal pressure, tension in the thoracolumbar fascia (TLF), increase sacroiliac joint (SIJ) stiffness, and enhance segmental rigidity and alignment of the lumbar vertebrae. Although the ISS does not actively contribute to motion, the increased intra-abdominal pressure may decompress/traction the spine during motion. Further, an increase in intra-abdominal pressure, segmental rigidity, and TLF stiffness may aid in eccentrically decelerating spinal flexion and lateral flexion. The ISS is "the stabilization subsystem". Analogous to the rotator cuff of the shoulder, its optimal function may be essential for optimal performance of the other subsystems (muscles of the trunk). Inhibition of the ISS most often results in synergistic dominance of the

Muscles of the intrisic stabilization subsystem including the TVA, diaphram, multifidus, and pelvic floor muscles

 None (potentially traction/decompression)

 Stabilization of the lumbar spine, SIJ, and pelvis

 Contributes to eccentric deceleration of lumbar flexion and lateral flexion.

Dr. Brent Brookbush demonstrating an asymmetrical weight shift during an overhead squat assessment

Signs of ISS Under-activity 

Sample Program (Anterior Pelvic Tilt)

Anterior Thoracolumbar Fascia (TLF), Posterior Abdominal Fascia & More:

A rendering of a cross section of the torso showing the location of the trunk musculature

Transverse Abdominis

Image of the transverse abdominis running from the midline of the body to the pelvis and ribcage

Internal Obliques

The attachment of the obliques on the pelvis, abdominal fascia, ligamentum nuchae, and ribcage

Diaphragm

Pelvic Floor

Muscles of the hip, lumbar spine, pelvis, and pelvic floor

Multifidus

Rotatores, Intertransversarii, and Interspinales

The location and boney attachments of the multifidi of the back

Quadratus Lumborum

Psoas

The psoas and iliacus muscles attaching into the lumbar spine, pelvis, and femur

Research Corner

Summary of Research Findings

The fascial component of this myofascial synergy may be a spherical sheath that includes the anterior and middle layers of the TLF fascia, the posterior abdominal fascia, the investing fascia of the diaphragm, and the fascia of the pelvic floor muscles.

The muscles investing in this fascial sheath include the transverse abdominis (TVA), internal obliques, pelvic floor (levator ani and coccygeus), diaphragm, multifidus, rotatores, interspinales & intertransversarii, and potentially the quadratus lumborum and psoas.

The ISS is a stabilization subsystem that does not function in isolation, but in synergy with subsystems better suited for movement.

 enhance stability by increasing tension in the TLF, compressing the (force closure) SIJ, and decreasing intra-abdominal volume which may increase intra-abdominal pressure.

Lumbo Pelvic Hip Complex Dysfunction (LPHCD)

 results in a decrease in TVA and internal obliques activity.

Although the internal obliques can function as the external obliques, they behave like the TVA.

The diaphragm may adopt a higher average activity level and lower position in response to stability demands (likely contributing to an increase in intra-abdominal pressure)

Pain and dysfunction result in the diaphragm adopting a lower average activity level, higher relative position, more rigid stabilization strategy, and faster time to fatigue.

The pelvic floor muscles (PFM) are recruited with the TVA, internal obliques, and diaphragm.

Contracting the PFM during ISS exercise may increase TVA activity.

The multifidus function like other stabilizing muscles of the spine (including the TVA, pelvic floor, and diaphragm)

The compensatory pattern adopted by the multifidus in those exhibiting dysfunction suggests a muscle that is short/over-active.

The rotatores, intertransversarii, and interspinales may act as a sensory organ, initiating a reflexive increase in activity of the muscles of the ISS when lengthened.

Recovery from multifidus atrophy is best accomplished via stabilization exercise, not loaded extension.

The quadratus lumborum and psoas are recruited and compensate (short/over-active) similar to the multifidus, and show the same atrophy and morphological change in those with chronic low back pain.

The ADIM and quadruped (stability exercise) are effective for enhancing the recruitment and hypertrophy of ISS muscles.

The Muscles of the ISS can be separated into 2 categories:

 (Less or latent recruitment, a relative increase in length, decrease in force production, quicker to fatigue)

Pelvic floor (levator ani and coccygeus),

 (Higher average activity, prone to spikes, higher activity level for longer after lifting, loss of bilateral activation in response to load, may show marked atrophy in those with chronic low back pain)

Rotatores, interspinales & intertransversarii

Dr. Brent Brookbush demonstrating a dynamic quadruped (bear crawl), which is an activation exercise for the TVA

More on Function

Influence on Intervention

Signs of ISS Underactivity

Best-use and Progressions

Practical Application

Activation Progressions for the Intrinsic Stabilization Subsystem

Alternate Progressions: Gamification ("Simon Says")

Alternate Progression: Quadruped with Glute Activation

Alternate Progression: Quadruped with Ball Resisted Cervical Retraction

Alternate Progression: Hardest Quadruped Progression Ever

Transverse Abdominis Isolated Activation (Quadrupeds)

Gali-Peds (Quadrupeds with Stability Ball)

Quadruped Crawl (Dynamic Quadruped)

Additional Quadruped Crawl Progressions

Transverse Abdominis and Deep Cervical Flexor (DCF) Activation

Transverse Abdominis and Gluteus Maximus Activation Progression

Hardest Quadruped Progression Ever

Isolated Activations

Crunch and Catch – Soccer Throw on Floor

Crunch and Catch – unilateral “Baseball throw” on Floor

Crunch and Catch – Soccer Throw on Bosu

Crunch and Catch – unilateral “Baseball throw” on Bosu

Crunch and Catch – Soccer Throw on Ball

Crunch and Catch – unilateral “Baseball throw on Ball

Crunch and Catch

Crunch and Catch Progressions

Reactive Activation Progressions

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Intrinsic Stabilization Subsystem (ISS) Integration