Introduction

Summary of Research Findings

More on Function

Influence on Intervention

Signs of ISS Underactivity

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

Transverse Abdominis

Internal Obliques

Diaphragm

Pelvic Floor

Multifidus

Rotatores, Intertransversarii, and Interspinales

Psoas

Intrinsic Stabilization Subsystem (ISS) Integration

NASM

AOTA

PTAGlobal

REPS

AUSactive

WITS

CIMSPA

TPTA

ISSA

YOGA

NCBTMB

NYPT

REPSI

AUSPHYSIO

AFAA

PACE

ACSM

ProCert

CanFitPro

Intrinsic Stabilization Subsystem (ISS)

Intrinsic Stabilization Subsystem

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 <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> 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, <a id="integration" data-tip="1472" target="_blank" href="/glossary-term/integration" class="glossary">integration</a> techniques and a sample routine.
<h4>The Intrinsic Stabilization Subsystem is comprised of:</h4>
<ul>
 <li>Transverse Abdominis (TVA)</li>
 <li><a href="https://brookbushinstitute.com/courses/internal-obliques">Internal Obliques</a></li>
 <li>Pelvic Floor (Levator ani, coccygeus, and associated fascia)</li>
 <li>Diaphragm</li>
 <li>Multifidus</li>
 <li>Rotatores, Interspinales &amp; Intertransversarii</li>
 <li>Abdominal Fascia (<a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> layer)</li>
 <li>Continuous with investing fascia of Diaphragm and Pelvic Floor</li>
 <li>Thoracolumbar Fascia (TLF) (<a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> and middle layer)
 <ul>
 <li>Potentially
 <ul>
 <li>Quadratus Lumborum</li>
 <li>Psoas</li>
 </ul>
 </li>
 </ul>
 </li>
</ul>
The concepts and techniques described in this course may be particularly beneficial for neuromuscular re-education, coordination, motor pattern <a id="integration" data-tip="1472" target="_blank" href="/glossary-term/integration" class="glossary">integration</a>, 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 <a id="integration" data-tip="1473" target="_blank" href="/glossary-term/integration" class="glossary">integrated</a> exercise programs, sports performance programs, and therapeutic (rehabilitation) interventions.
<h4>&#xA0;For additional self-administered joint mobilization techniques check out:</h4>
<ul>
 <li><a href="https://brookbushinstitute.com/courses/anterior-oblique-subsystem-aos">Anterior Oblique Subsystem (AOS)</a></li>
 <li><a href="https://brookbushinstitute.com/courses/posterior-oblique-subsystem-pos">Posterior Oblique Subsystem (POS)</a></li>
 <li><a href="https://brookbushinstitute.com/courses/deep-longitudinal-subsystem">Deep Longitudinal Subsystem (DLS)</a></li>
</ul>

Course Description: Intrinsic Stabilization Subsystem

Review of Core Subsystems

<h3><a href="https://www.datocms-assets.com/25800/1684183337-intrinsic-stabilization-subsystem-study-guide-pdf.pdf" title="Quick Study Guide: Intrinsic Stabilization Subsystem (ISS)" target="_blank" rel="noopener">Quick Study Guide: Intrinsic Stabilization Subsystem (ISS)</a></h3>
<h3>Function (Brief):</h3>
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, <a id="tension" data-tip="1229" target="_blank" href="/glossary-term/tension" class="glossary">tension</a> 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 <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> flexion. The ISS is &quot;the stabilization subsystem&quot;. Analogous to the rotator cuff of the shoulder, its <a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a> function may be essential for <a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a> performance of the other subsystems (muscles of the trunk). Inhibition of the ISS most often results in <a id="synergistic-dominance" data-tip="1643" target="_blank" href="/glossary-term/synergistic-dominance" class="glossary">synergistic dominance</a> of the <a href="https://brookbushinstitute.com/courses/anterior-oblique-subsystem-aos" target="_blank" rel="noopener"> </a><a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">Anterior</a> Oblique Subsystem (AOS).
<img title="Muscles of the intrisic stabilization subsystem including the TVA, diaphram, multifidus, and pelvic floor muscles" src="https://www.datocms-assets.com/25800/1649281673-intrinsic-stabilization-subsystem.jpg" width="307" height="334" alt="The muscles of the intrinsic stabilization subsystem">
<ul>
 <li> Concentric Function: None (potentially traction/decompression)</li>
 <li> Isometric Function: Stabilization of the lumbar spine, SIJ, and pelvis</li>
 <li> Eccentric Function: Contributes to eccentric deceleration of lumbar flexion and <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> flexion.</li>
</ul>
<h3> Common Maladaptive Behavior </h3>
<ul>
 <li>Under-active</li>
</ul>

<ul>
 <li>
 <h4>Abdominal <a id="drawing-in" data-tip="1580" target="_blank" href="/glossary-term/drawing-in" class="glossary">Drawing-in</a> Maneuver (<a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a>)</h4>
 <ul>
 <li>Inability to perform the Abdominal <a id="drawing-in" data-tip="1580" target="_blank" href="/glossary-term/drawing-in" class="glossary">Drawing-in</a> Maneuver (<a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a>)</li>
 <li>Inability to perform the <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> without co-contraction of the <a href="https://brookbushinstitute.com/courses/rectus-abdominis-pyramidalis" target="_blank" rel="noopener"> rectus abdominis </a> and <a href="https://brookbushinstitute.com/courses/external-obliques" target="_blank" rel="noopener"> external obliques </a></li>
 <li>Abdominal distension during functional activities</li>
 </ul>
 </li>
 <li> <a href="https://brookbushinstitute.com/courses/solutions-table-overhead-squat-assessment" target="_blank" rel="noopener"> Overhead Squat </a><a id="assessment" data-tip="1478" target="_blank" href="/glossary-term/assessment" class="glossary">Assessment</a> 
 <ul>
 <li>Abdominal Distension</li>
 <li><a href="https://brookbushinstitute.com/video/overhead-squat-assessment-9-anterior-pelvic-tilt-excessive-lordosis" target="_blank" rel="noopener"> Excessive lordosis </a></li>
 <li><a href="https://brookbushinstitute.com/video/overhead-squat-assessment-8-excessive-forward-lean" target="_blank" rel="noopener"> Excessive forward lean </a></li>
 <li><a href="https://brookbushinstitute.com/video/overhead-squat-assessment-15-sign-clusters-asymmetrical-weight-shift" target="_blank" rel="noopener"> Asymmetrical weight shift </a></li>
 <li><a href="https://brookbushinstitute.com/video/overhead-squat-assessment-17-sign-clusters-posterior-pelvic-tilt-butt-wink-and-inadequate-forward-lean-breakdown" target="_blank" rel="noopener"> Inadequate forward lean</a></li>
 </ul>
 </li>
</ul>
<img title="Dr. Brent Brookbush demonstrating an asymmetrical weight shift during an overhead squat assessment" src="https://www.datocms-assets.com/25800/1649876308-asymmerical-2.jpg" width="292" height="407" alt="Example of an asymmetrical weight shift">
<h3>Practical Application </h3>
<ul>
 <li> Core 
 <ul>
 <li><a href="https://brookbushinstitute.com/courses/transverse-abdominis-activation-quadrupeds-progressions" target="_blank" rel="noopener"> Quadruped </a><a id="exercise-progression" data-tip="1182" target="_blank" href="/glossary-term/exercise-progression" class="glossary">Progressions</a> (TVA Activation)</li>
 </ul>
 </li>
 <li> <a id="integration" data-tip="1473" target="_blank" href="/glossary-term/integration" class="glossary">Integrated</a> Exercise 
 <ul>
 <li>N/A</li>
 </ul>
 </li>
</ul>

Signs of ISS Under-activity 

<h3>Mobility</h3>
<ul>
 <li><a id="release" data-tip="1249" target="_blank" href="/glossary-term/release" class="glossary">Release</a>
 <ul>
 <li><a href="https://brookbushinstitute.com/video/tensor-fasciae-latae-gluteus-minimus-and-vastus-lateralis-vibration-release" target="_blank" rel="noopener"> Tensor fascia latae (TFL) and glute minimus vibration </a><a id="release" data-tip="1249" target="_blank" href="/glossary-term/release" class="glossary">Release</a> </li>
 <li><a href="https://brookbushinstitute.com/video/quadriceps-and-rectus-femoris-vibration-release" target="_blank" rel="noopener"> Rectus femoris vibration </a><a id="release" data-tip="1249" target="_blank" href="/glossary-term/release" class="glossary">Release</a> </li>
 <li><a href="https://brookbushinstitute.com/video/latissimus-dorsi-rhomboids-teres-major-and-posterior-deltoid-vibration-release" target="_blank" rel="noopener"> Latissimus dorsi vibration </a><a id="release" data-tip="1249" target="_blank" href="/glossary-term/release" class="glossary">Release</a> </li>
 </ul>
 </li>
 <li>Mobilization
 <ul>
 <li><a href="https://brookbushinstitute.com/video/thoracic-spine-rotational-mobilization-stability-and-strengthening-exercise" target="_blank" rel="noopener"> Thoracic spine rotational mobilization </a></li>
 <li><a href="https://brookbushinstitute.com/video/self-administered-hip-mobilization-anterior-to-posterior-with-flexion" target="_blank" rel="noopener"> Self-administered Hip Mobilization (</a><a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">Anterior</a> to <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">Posterior</a> with Flexion) </li>
 </ul>
 </li>
 <li>Lengthen
 <ul>
 <li><a href="https://brookbushinstitute.com/video/latissimus-dorsi-and-erector-spinae-static-stretch-childs-pose" target="_blank" rel="noopener"> Child&apos;s pose </a></li>
 <li><a href="https://brookbushinstitute.com/video/kneeling-hip-flexor-static-stretch" target="_blank" rel="noopener"> Kneeling hip flexor static stretch </a></li>
 </ul>
 </li>
</ul>
<h3>Activity</h3>
<ul>
 <li>Isolated Activation
 <ul>
 <li><a href="https://brookbushinstitute.com/video/quick-glute-activation-circuit" target="_blank" rel="noopener"> Glute activation circuit </a></li>
 <li><a href="https://brookbushinstitute.com/video/quadruped-crawl" target="_blank" rel="noopener"> Dynamic quadrupeds </a></li>
 </ul>
 </li>
 <li>Core
 <ul>
 <li><a href="https://brookbushinstitute.com/video/ultimate-glute-bridge" target="_blank" rel="noopener"> Ultimate glute bridge </a></li>
 <li><a href="https://brookbushinstitute.com/video/static-standing-chop-pattern" target="_blank" rel="noopener"> Standing chop pattern </a></li>
 </ul>
 </li>
 <li><a id="integration" data-tip="1472" target="_blank" href="/glossary-term/integration" class="glossary">Integration</a>
 <ul>
 <li><a href="https://brookbushinstitute.com/video/step-up-to-row" target="_blank" rel="noopener"> Step up to row</a></li>
 </ul>
 </li>
</ul>

Sample Program (Anterior Pelvic Tilt)

Research Corner

The fascial component of this myofascial synergy may be a spherical sheath that includes the <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> and middle layers of the TLF fascia, the <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> abdominal fascia, the investing fascia of the diaphragm, and the fascia of the pelvic floor muscles.
<ul>
 <li> Front: <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">Posterior</a> layer of abdominal fascia</li>
 <li> Sides: Fascia of the <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener"> internal obliques </a> and transverse abdominis</li>
 <li> Back: <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">Anterior</a> and middle layers of the TLF</li>
 <li> Top: Investing fascia of the diaphragm</li>
 <li> Bottom: Investing fascia of the pelvic floor</li>
</ul>
The fascia of the <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener">internal obliques</a> and transverse abdominis comprise the <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> wall of a loop that continues to <a id="posture" data-tip="1660" target="_blank" href="/glossary-term/posture" class="glossary">form</a> the <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> layer of the abdominal fascia anteriorly, and the middle layer of the TLF posteriorly (1, 3-9). The middle layer of the TLF would also be continuous with the layer of TLF fascia that envelopes the multifidus (extensor retinaculum). There is not much published on the <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> layer of the TLF, likely because it is the thinnest of the 3 layers and may not contribute much to lumbar <a id="stability" data-tip="1191" target="_blank" href="/glossary-term/stability" class="glossary">stability</a> (3, 9). However, this layer may aid in communication between investing muscles. It envelops the psoas and quadratus lumborum (QL), may run continuous with the internal fascia of the transverse abdominis, and potentially invests in the fascia of the pelvic floor and diaphragm. The continuity of these fascial linings seems likely, however, more research is needed. Further, the relationships between this investing layer of fascia, the transverse fascia, and the peritoneum should also be the subject of further study.
As mentioned above, the ISS is a stabilization subsystem that does not function in isolation, but in synergy with subsystems better suited for movement. This notion is supported by research on fascial relationships and <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> recruitment.
 The <a href="https://brookbushinstitute.com/article/anterior-oblique-subsystem-aos" target="_blank" rel="noopener"> AOS </a> and ISS: Below the level of the arcuate line, the <a href="https://brookbushinstitute.com/glossary/posterior/" target="_blank" rel="noopener">posterior</a> sheath does not continue, and the fascia of the <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener">internal obliques</a>, <a href="https://brookbushinstitute.com/courses/external-obliques" target="_blank" rel="noopener"> external obliques</a>, and transverse abdominis fuse and continue <a href="https://brookbushinstitute.com/glossary/anterior/" target="_blank" rel="noopener">anteriorly</a> to the <a href="https://brookbushinstitute.com/courses/rectus-abdominis-pyramidalis" target="_blank" rel="noopener">rectus abdominis </a> (1). Studies also demonstrate that force imparted by any trunk <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> will be transmitted between all layers of the abdominal fascial network (13, 14). Last, research shows any significant <a href="https://brookbushinstitute.com/glossary/lateral/" target="_blank" rel="noopener">lateral</a>, <a href="https://brookbushinstitute.com/glossary/posterior/" target="_blank" rel="noopener"> posterior</a>, or rotational force will result in an increase in <a href="https://brookbushinstitute.com/courses/rectus-abdominis-pyramidalis" target="_blank" rel="noopener">rectus abdominis</a>, <a href="https://brookbushinstitute.com/courses/external-obliques" target="_blank" rel="noopener"> external obliques </a> (<a href="https://brookbushinstitute.com/article/anterior-oblique-subsystem-aos" target="_blank" rel="noopener">AOS </a> Activity), <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener"> internal obliques</a>, and <a href="https://brookbushinstitute.com/article/transverse-abdominis" target="_blank" rel="noopener">transverse abdominis</a> activity (2), and may increase quadratus lumborum and psoas activity (10-12) ( ISS activity). The fusion of abdominal fascial layers, research demonstrating the transmission of force, and research on recruitment strategies suggest a synergistic relationship and fascial connection between the <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> abdominal fascia and the <a href="https://brookbushinstitute.com/courses/anterior-oblique-subsystem-aos" target="_blank" rel="noopener"> AOS</a>, and the middle and <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> layers of abdominal fascia and the ISS.
 The <a href="https://brookbushinstitute.com/courses/posterior-oblique-subsystem-pos" target="_blank" rel="noopener"> POS</a>, <a href="https://brookbushinstitute.com/courses/deep-longitudinal-subsystem" target="_blank" rel="noopener"> DLS</a>, and ISS: Research by Stevens et al. and DeRiddler et al. have demonstrated the coordinated recruitment of the multifidus, <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener"> internal obliques </a> (ISS), <a href="https://brookbushinstitute.com/courses/erector-spinae" target="_blank" rel="noopener"> erector spinae </a> (<a href="https://brookbushinstitute.com/courses/deep-longitudinal-subsystem" target="_blank" rel="noopener">DLS</a>), <a href="https://brookbushinstitute.com/courses/external-obliques" target="_blank" rel="noopener"> external obliques</a>, <a href="https://brookbushinstitute.com/courses/rectus-abdominis-pyramidalis" target="_blank" rel="noopener"> rectus abdominis </a> (<a href="https://brookbushinstitute.com/courses/anterior-oblique-subsystem-aos" target="_blank" rel="noopener">AOS</a>), <a href="https://brookbushinstitute.com/courses/latissimus-dorsi" target="_blank" rel="noopener"> latissimus dorsi</a>, and <a href="https://brookbushinstitute.com/courses/gluteus-maximus" target="_blank" rel="noopener">gluteus maximus </a> (POS) during quadrupeds and an extension exercise (&quot;reverse-hypers&quot;) (18, 19). Further, an interesting study by Vleeming et al. demonstrated inflation of the deep <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> layer by extensor muscles (of the <a href="https://brookbushinstitute.com/courses/deep-longitudinal-subsystem" target="_blank" rel="noopener"> DLS</a>) altered the moment arm and load angle of muscles investing in the superficial <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> layer and middle layer of the TLF (<a href="https://brookbushinstitute.com/courses/posterior-oblique-subsystem-pos" target="_blank" rel="noopener">POS </a> and ISS)(17). This research implies that although the layers of the TLF may be separated, and subsystems categorized by function, the investing musculature works in a coordinated fashion.
Note, the fascial layers of the ISS are not generally addressed directly. The ISS, as a subsystem, is generally targeted with stabilization type exercise, specifically <a href="https://brookbushinstitute.com/courses/transverse-abdominis-activation-quadrupeds-progressions" target="_blank" rel="noopener"> TVA Activation</a>.
<a href="https://brookbush.s3.us-east-2.amazonaws.com/wordpress/wp-content/uploads/2013/06/b38_thoraco-lumbar_section.jpg" target="_blank" rel="noopener"><img src="https://www.datocms-assets.com/25800/1650603392-thoraco-lumbarsection.jpg" title="A rendering of a cross section of the torso showing the location of the trunk musculature" alt="Cross section showing the muscles of the torso"></a> Consider how <a id="bilateral" data-tip="1552" target="_blank" href="/glossary-term/bilateral" class="glossary">bilateral</a> contraction of the TVA would increase <a id="tension" data-tip="1229" target="_blank" href="/glossary-term/tension" class="glossary">tension</a> on the thoracolumbar fascia, pulling laterally on both sides simultaneously increasing rigidity. Further, consider how an increase in pressure <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> to the lumbar vertebrae would resist and <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> translation and <a id="glide" data-tip="1817" target="_blank" href="/glossary-term/glide" class="glossary">shear</a>. - http://www.bandhayoga.com/online-courses/online-courses/shaktitest/images/Blog/b38_thoraco-lumbar_section.jpg

<div id="attachment_2126" class="wp-caption aligncenter">
 The function of the transverse abdominis (TVA) is relatively well researched and will serve as a <a id="model" data-tip="1469" target="_blank" href="/glossary-term/model" class="glossary">model</a> for understanding similar behavior in other muscles of the ISS. The TVA contracts prior to planned activity, bilaterally regardless of the direction of limb motion, and activity increases with changes in <a id="posture" data-tip="1658" target="_blank" href="/glossary-term/posture" class="glossary">posture</a> including the increased <a id="center-of-mass-gravity" data-tip="1187" target="_blank" href="/glossary-term/center-of-mass-gravity" class="glossary">center of gravity</a> height, increased respiration, and speed of locomotion (20-24). The stabilizing function of the TVA appears to occur by two primary mechanisms. First, increased <a id="tension" data-tip="1229" target="_blank" href="/glossary-term/tension" class="glossary">tension</a> in the <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> results in increased <a id="tension" data-tip="1229" target="_blank" href="/glossary-term/tension" class="glossary">tension</a> of the thoracolumbar fascia (<a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> and middle layers of the TLF) resulting in increased stiffness of the lumbar spine and <a id="force-closure" data-tip="1448" target="_blank" href="/glossary-term/force-closure" class="glossary">force closure</a> of the sacroiliac joint (25-31). TVA contraction (along with the other muscles of the ISS) also results in a decrease in intra-abdominal volume and an increase in intra-abdominal pressure, which increases rigidity of the spine, may decompress the spine, and resist flexion <a id="torque" data-tip="1294" target="_blank" href="/glossary-term/torque" class="glossary">torque</a> (32-34). In studies by Morris et al. and Hodges et al. asymmetrical firing of the TVA was demonstrated with greater resistance and speed, and synergy was demonstrated between the TVA, obliques, and lumbar multifidus muscles (35-38). This implies that the TVA contracts bilaterally and relatively equally at lower intensities, and as larger forces are generated by the limbs (either due to increased weight or velocity), activity of the TVA on the more stressed side increases to match the additional load, and additional muscles (<a href="https://brookbushinstitute.com/courses/anterior-oblique-subsystem-aos" target="_blank" rel="noopener">AOS</a>) are recruited.
 In 1996, Hodges et al. published a pivotal study that demonstrated the <a href="https://brookbushinstitute.com/article/transverse-abdominis" target="_blank" rel="noopener"> TVA </a> fired prior to the initiation of arm swing in asymptomatic individuals but fired after the initiation of arm swing in individuals with low back pain (39). Hodges et al. would follow up this study with research demonstrating that the same pattern also occurred during leg movement, various speeds of arm movement, and demonstrated the same altered recruitment pattern could be acutely created with injection-induced low back pain (40-43). Further, they would show that low back pain results in not only decreased recruitment of intrinsic muscles ( TVA, obliques, and lumbar multifidus ) but increased reliance on &#x201C;global muscles&#x201D; (44). More recent research has demonstrated that altered recruitment patterns increase the likelihood of low back pain/injury in the following year, that unresolved altered recruitment patterns result in worse outcomes a year post-physical therapy, changes in TVA recruitment patterns correlate strongly with a disability index, and that even adductor/groin injury/pain may result in altered TVA recruitment strategies (45-48).
 The practical application of TVA research is the inclusion of exercise that challenges or cues the &#x201C;abdominal <a id="drawing-in" data-tip="1580" target="_blank" href="/glossary-term/drawing-in" class="glossary">drawing-in</a> maneuver&#x201D; (<a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a>) (during <a href="https://brookbushinstitute.com/courses/transverse-abdominis-activation-quadrupeds-progressions" target="_blank" rel="noopener">quadrupeds</a> may be best).
 <ul>
 <li> Abdominal <a id="drawing-in" data-tip="1580" target="_blank" href="/glossary-term/drawing-in" class="glossary">Drawing-in</a> Maneuver (<a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a>) &#x2013; A light contraction of the transverse abominis (and potentially the entire <a href="https://brookbushinstitute.com/courses/intrinsic-stabilization-subsystem" target="_blank" rel="noopener">intrinsic stabilization subsystem </a> ) is achieved by gently pulling the lower abdominal region away from one&#x2019;s waistband. This should have minimal effect on breathing, and should not be confused with a maximal contraction of the transverse abdominis resulting in a &#x201C;vacuum pose&#x201D;.</li>
 </ul>
 <img title="Image of the transverse abdominis running from the midline of the body to the pelvis and ribcage" src="https://www.datocms-assets.com/25800/1649273500-tva.png" alt="The transverse abdominis muscle on the torso">
 Research has investigated the <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> as <a id="assessment" data-tip="1478" target="_blank" href="/glossary-term/assessment" class="glossary">assessment</a>, as exercise, and as a cue during functional movement patterns in those with low back pain. Low back pain has been shown to reduce the ability to perform the <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> (49), and conversely, the <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> has been shown to be a <a id="reliability" data-tip="1795" target="_blank" href="/glossary-term/reliability" class="glossary">reliable</a> <a id="assessment" data-tip="1478" target="_blank" href="/glossary-term/assessment" class="glossary">assessment</a> of decreased TVA function (50). Cueing the <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> has been shown to preferentially recruit the TVA, to the exclusion of more superficial muscles (<a href="https://brookbushinstitute.com/courses/rectus-abdominis-pyramidalis" target="_blank" rel="noopener">rectus abdominis</a> and <a href="https://brookbushinstitute.com/courses/external-obliques" target="_blank" rel="noopener">external obliques</a>) (51), and has been shown to be effective for increasing TVA contraction during more functional tasks (52). <a id="specificity" data-tip="1224" target="_blank" href="/glossary-term/specificity" class="glossary">Specific</a> training of deep muscles results in an immediate change to recruitment strategies, neutral spine has been demonstrated to result in greater TVA thickness, and somewhat strangely, adding ankle dorsiflexion to <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> exercises also increases TVA activity (53-56). Quadrupeds <a href="https://brookbushinstitute.com/courses/transverse-abdominis-activation-quadrupeds-progressions" target="_blank" rel="noopener"> (TVA Activation) </a> with cueing of the <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> resulted in similar TVA activity in asymptomatic individuals and those with low back pain, which may suggest this exercise is ideal for normalizing recruitment patterns (57). Leg raises resulted in greater TVA activity; however, this exercise also sharply increased <a href="https://brookbushinstitute.com/courses/erector-spinae" target="_blank" rel="noopener">erector spinae</a> activity (a <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> <a id="prone" data-tip="1561" target="_blank" href="/glossary-term/prone" class="glossary">prone</a> to over-activity) (58). Although interventions should be based on <a id="assessment" data-tip="1478" target="_blank" href="/glossary-term/assessment" class="glossary">assessment</a>, research has demonstrated that generally, stabilization exercise results in better outcomes than stretching, and a &#x201C;segmental stabilization (TVA Activation) &#x201D; approach results in better outcomes than global <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> training for low back pain (59, 60). Correlations have been made between TVA thickness, lumbar <a id="stability" data-tip="1191" target="_blank" href="/glossary-term/stability" class="glossary">stability</a>, and <a id="balance" data-tip="1190" target="_blank" href="/glossary-term/balance" class="glossary">balance</a>, which may have implications for injury prevention and sports performance (61).
 The <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> as a cue during functional activities, and <a href="https://brookbushinstitute.com/courses/transverse-abdominis-activation-quadrupeds-progressions" target="_blank" rel="noopener">quadrupeds</a> with <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> for core exercise are the interventions recommended by the Brookbush Institute for those exhibiting signs of TVA under-activity. In fact, these recommendations are recommended for <a id="integration" data-tip="1472" target="_blank" href="/glossary-term/integration" class="glossary">integration</a> of the ISS as a whole, as the remainder of this article will cover how muscles investing in the fascial sheath is noted. above are recruited in conjunction with the TVA and benefit from similar exercise.
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 The <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener">internal obliques</a> can perform the same actions as the <a href="https://brookbushinstitute.com/courses/external-obliques" target="_blank" rel="noopener">external obliques</a> but behave like the transverse abdominis. Studies have demonstrated these muscles are active during rotation (62), have the potential to contribute to side bending (63), and may contribute to flexion via transmission of force through the semilunar lines (64). However, <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener"> internal obliques</a> activity also increases with increases in respiration and gait speed (similar to the transverse abdominis) (23), are recruited <a href="https://brookbushinstitute.com/glossary/bilateral/" target="_blank" rel="noopener">bilaterally</a> when lifting asymmetric loads (unlike the <a href="https://brookbushinstitute.com/courses/external-obliques" target="_blank" rel="noopener">external obliques</a>) (66), and activity increases when the spine is compressed, perhaps contributing to the &#x201C;unloading/decompression&#x201D; force generated when intra-abdominal pressure increases (34, 67). The <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener">internal obliques</a> invest in the thoracolumbar fascia, enabling them to contribute to <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> force on the spinous process (primarily below L3), <a id="compression" data-tip="1595" target="_blank" href="/glossary-term/compression" class="glossary">compression</a> (<a id="force-closure" data-tip="1448" target="_blank" href="/glossary-term/force-closure" class="glossary">force closure</a>) of the sacroiliac joint (SIJ), and as mentioned above, increased intra-abdominal pressure via the abdominal tourniquet (25, 26, 29) Note: the <a href="https://brookbushinstitute.com/courses/external-obliques" target="_blank" rel="noopener">external obliques</a> do not invest in the TLF (68).
 In two studies by Ng et al., increased <a href="https://brookbushinstitute.com/courses/external-obliques" target="_blank" rel="noopener">external obliques</a> activity and decreased <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener">internal obliques</a> activity was noted during static and dynamic <a id="axial-skeleton" data-tip="1292" target="_blank" href="/glossary-term/axial-skeleton" class="glossary">axial</a> rotation in those exhibiting symptoms of low back pain (69, 70). Further, decreased <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener">internal obliques</a> activity has been noted in those with &#x201C;sway back&#x201D; <a id="posture" data-tip="1658" target="_blank" href="/glossary-term/posture" class="glossary">posture</a>, and those exhibiting SIJ pain (71, 72). Although not always mentioned, the <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener">internal obliques</a> are commonly studied in conjunction with the transverse abdominis. For example, Hodges et al. demonstrated that the <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener">internal obliques</a> and the transverse abdominis fired before lower extremity activity in asymptomatic individuals, but both muscles demonstrated latent firing patterns in those with low back pain (21). Further, in the study by Chon et al., adding dorsiflexion to exercises using the abdominal <a id="drawing-in" data-tip="1580" target="_blank" href="/glossary-term/drawing-in" class="glossary">drawing-in</a> maneuver (<a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a>) increased activity of the <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener">internal obliques</a> as well as the TVA (56). In summary, despite having the potential to contribute to the same actions as the <a href="https://brookbushinstitute.com/courses/external-obliques" target="_blank" rel="noopener">external obliques</a>, the <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener">internal obliques</a> behave like the TVA, including responding similarly to the <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a>.
 <img title="The attachment of the obliques on the pelvis, abdominal fascia, ligamentum nuchae, and ribcage" src="https://www.datocms-assets.com/25800/1648089884-1642105171-obliques.png" alt="The oblique muscles on the lateral side of the body">
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Hodges et al. (73) describes the relationship between breathing, diaphragm activity, and <a id="posture" data-tip="1659" target="_blank" href="/glossary-term/posture" class="glossary">postural</a> change as &#x201C;time-locked&#x201D; and potentially linked via reflex. Two studies by Hodges et al. demonstrated that stimulus of the diaphragm resulted in increased stiffness of the spine (74, 75), and various studies have noted a change in diaphragm activity during lifting, changes in position and <a id="posture" data-tip="1658" target="_blank" href="/glossary-term/posture" class="glossary">posture</a>, movement of the limbs, and changes in gait speed (73, 76-79, 81-82). A study by Hodges et al. may give inference of how the diaphragm accomplishes respiration and stabilization concurrently. In this study, repetitive upper body motion (arm swings) resulted in an increase in average diaphragm activity (EMG) (78). Further, a study by Kolar et al. demonstrated lower average activity and a higher relative position in those exhibiting low back pain (80). Based on these findings we may be able to assume that <a id="posture" data-tip="1659" target="_blank" href="/glossary-term/posture" class="glossary">postural</a> <a id="stability" data-tip="1191" target="_blank" href="/glossary-term/stability" class="glossary">stability</a> with respiration is accomplished by higher average activity and a lower relative position, decreasing intra-abdominal space and increasing intra-abdominal pressure. This pattern is disrupted in those exhibiting signs of pain and dysfunction.
Lower activity/higher relative position may be part of the compensatory pattern associated with low back pain. The studies by Kolar et al. and Hodges et al. (78, 80) mentioned above are supported with additional studies on diaphragm activity and impairment (81, 83-86). Hodges et. al, demonstrated less diaphragmatic motion and activity in low back pain patients (86). Further, Vastatek et al. demonstrated that those with sacroiliac joint (SIJ) pain exhibited altered diaphragm activity during isometric lifting of the limbs; activity returned to normal when the SIJ was stabilized via manual <a id="compression" data-tip="1595" target="_blank" href="/glossary-term/compression" class="glossary">compression</a> of the pelvis (83). Several studies have noted increases in respiratory demand, and/or diaphragm fatigue results in a loss of lumbar <a id="stability" data-tip="1191" target="_blank" href="/glossary-term/stability" class="glossary">stability</a> (81, 85, 86). The studies by Jansen et al. demonstrate that low back patients are quicker to diaphragm fatigue, and that diaphragm fatigue resulted in a more rigid stabilization pattern during lifting (81, 85). Last, a study by McGill et al. demonstrated that <a id="compression" data-tip="1595" target="_blank" href="/glossary-term/compression" class="glossary">compression</a> and <a id="glide" data-tip="1817" target="_blank" href="/glossary-term/glide" class="glossary">shear</a> forces on the spine increase when ventilatory demand increases (87), which may imply that research is needed to determine the correlation between diaphragm activity and injury. Considering these studies together, the compensatory pattern adopted by the diaphragm in those exhibiting pain and dysfunction may be a lower average activity, a higher relative position, with smaller excursion during respiration, which results in a more rigid (and likely weaker) stabilization strategy resulting in quicker fatigue, which in turn results in larger <a id="glide" data-tip="1817" target="_blank" href="/glossary-term/glide" class="glossary">shear</a> and <a id="compression" data-tip="1596" target="_blank" href="/glossary-term/compression" class="glossary">compressive forces</a> on the spine during motion and <a id="posture" data-tip="1659" target="_blank" href="/glossary-term/posture" class="glossary">postural</a> change. To date, no prospective studies are available to determine whether altered diaphragm activity and motion may increase the risk of injury; however, studies have demonstrated that altered core control is correlated with an increased risk of injury (88, 89).
<h4> Hypothesized compensation pattern of the diaphragm: </h4>
<ol>
 <li>Lower average activity</li>
 <li>Higher relative position</li>
 <li>Decrease in excursion with respiration</li>
 <li>More rigid stabilization strategy (less change in response to changing stimulus)</li>
 <li>Quicker fatigue</li>
 <li>Larger <a id="glide" data-tip="1817" target="_blank" href="/glossary-term/glide" class="glossary">shear</a> and <a id="compression" data-tip="1596" target="_blank" href="/glossary-term/compression" class="glossary">compressive forces</a> on the lumbar spine</li>
</ol>
The study mentioned above by Vastatek et al. (83) implies that stabilization exercise may aid in both low back pain and diaphragm function. Further, a randomized control <a id="randomized-control-trial" data-tip="1407" target="_blank" href="/glossary-term/randomized-control-trial" class="glossary">trial</a> by Mehling et al. demonstrated that &#x201C;controlled-breath therapy&#x201D; was effective for the treatment of low back patients (90). Although core stabilization exercises are recommended by the Brookbush Institute (BI), &#x201C;controlled-breathe therapy&#x201D; admittedly deserves more attention. Based on the research and compensatory pattern above, it may be worth testing breathing from a higher activity/lower position. Not just deep breathing in and out, but breathing in deeper and trying to maintain normal tidal volume from a &#x201C;deeper place&#x201D;. This could be added to tasks that challenge <a id="stability" data-tip="1191" target="_blank" href="/glossary-term/stability" class="glossary">stability</a> (e.g. <a href="https://brookbushinstitute.com/video/static-standing-chop-pattern" target="_blank" rel="noopener">standing chops</a>).
The increase in activity with changes in <a id="posture" data-tip="1658" target="_blank" href="/glossary-term/posture" class="glossary">posture</a>, and the decrease in activity with increased length exhibited in those with signs of dysfunction is similar to the behavior of the TVA and <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener">internal obliques</a>.

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 Several studies indicate that the pelvic floor muscles (PFM) behave like, and in conjunction with, the diaphragm and TVA. A study by Hodges et al. that mirrors their pivotal 1996 study on TVA activity (39), demonstrated the PFM is active prior to deltoid activation during arm swing, and activity is not direction-specific (91). Sapsford et al. demonstrated that the voluntary activation of core muscles during various common exercises also recruited PFM (92). Madill and colleagues considered the activation sequence in reverse - voluntary contractions of the PFM resulted in an initial increase in lower vaginal pressure, along with an increase in PFM, <a href="https://brookbushinstitute.com/courses/rectus-abdominis-pyramidalis" target="_blank" rel="noopener"> rectus abdominus</a>, <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener"> internal obliques</a>, and TVA activity, with later increases in pressure (last 30% maximum pressure) being associated with primarily increases in &#xA0; <a href="https://brookbushinstitute.com/courses/rectus-abdominis-pyramidalis" target="_blank" rel="noopener"> rectus abdominus</a>, <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener"> internal obliques</a>, and TVA activity (93).
 One study was located that demonstrated individuals with chronic pelvic pain also had a higher incidence of signs that are commonly associated with Sacroiliac Joint Dysfunction (LSD) (94). A relationship between the pelvic floor and the sacroiliac joint seems very plausible, if for no other reason than the potential of a change in PFM <a id="lengthtension-relationship" data-tip="1685" target="_blank" href="/glossary-term/lengthtension-relationship" class="glossary">length/tension</a> with sacral motion. A study examining whether PFM activity continues to mimic the diaphragm and TVA in those experiencing low back pain should also be explored as a continuation of the work by Hodges et al. mentioned above (39).
 <a id="relevance" data-tip="1505" target="_blank" href="/glossary-term/relevance" class="glossary">Relevant</a> to exercise, a study by Critchley demonstrated that cueing PFM contraction during the quadruped exercise increased TVA contraction strength (95). This may suggest that although the PFM fires with the TVA reflexively, the addition of a voluntary PFM contraction may stimulate further recruitment of the TVA. Based on the function and behavior of the PFM the Brookbush Institute considers these muscles part of the Intrinsic Stabilization Subsystem (ISS), behaving like the TVA and diaphragm. Based on the function of the PFM and the results of the study by Critchley et al. and Culligan et al. (95, 96) it is unlikely that <a id="specificity" data-tip="1224" target="_blank" href="/glossary-term/specificity" class="glossary">specific</a> exercise is necessarily relative to LPHCD, but cueing a PFM contraction while doing ISS exercise may be beneficial.
 <a href="https://brookbush.s3.us-east-2.amazonaws.com/wordpress/wp-content/uploads/2014/01/mm_deep-front-line-Pelvic-floor.jpg" target="_blank" rel="noopener"><img src="https://www.datocms-assets.com/25800/1650603579-pelvic-floor.jpg" title="Muscles of the hip, lumbar spine, pelvis, and pelvic floor" alt="Muscle and connective tissue of the pelvic floor, including levator ani and obturator fascia"> </a>
 Obturator Fascia &#x2013; http://healingartsce.com/online-courses/online-courses/images/mm_deep-front-line-Pelvic-floor.jpg
 </div>
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 The middle layer of the thoracolumbar fascia (TLF) is continuous with the layer of TLF fascia that envelopes the multifidus (extensor retinaculum). The lumbar multifidus forms five distinct bands that are innervated segmentally by the <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> root corresponding to the vertebrae they attach to (97). The primary forces they contribute to are extension and <a id="compression" data-tip="1595" target="_blank" href="/glossary-term/compression" class="glossary">compression</a> with have some potential to contribute to <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> shear; however, fiber arrangement suggests a larger role in frontal plane stabilization (98-101). In a resting position, the multifidi are in a relatively shortened position, reaching <a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a> <a id="lengthtension-relationship" data-tip="1685" target="_blank" href="/glossary-term/lengthtension-relationship" class="glossary">length/tension</a> as the spine flexes (101). Although these muscles are often considered important to proprioception studies have demonstrated that these muscles have very low <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> spindle density (102-103).
 The multifidus seems to function primarily as stabilizers. Although these muscles contract ipsilaterally during weighted trunk rotation, they contract bilaterally during unweighted rotation (104). They are also active with spinal flexors during flexion and activity increases with increases in load (105). Further, during asymmetric lifting tasks, these muscles contract bilaterally (106). During isometric activities (holding a load in one hand) the multifidus contract first and fatigue faster when compared to the iliocostalis (107). Some distinctions may need to be made between deep and superficial fibers. Several studies have shown that the multifidus are only active during active <a id="posture" data-tip="1661" target="_blank" href="/glossary-term/posture" class="glossary">postures</a> (upright sitting, walking, swinging both arms forward) (107 - 109); however, a study by Moseley et al. demonstrated the deep fibers behaved more like the transverse abdominis and were active during static standing and during <a id="unilateral" data-tip="1551" target="_blank" href="/glossary-term/unilateral" class="glossary">unilateral</a> and <a id="bilateral" data-tip="1552" target="_blank" href="/glossary-term/bilateral" class="glossary">bilateral</a> arm swings in both directions (110). In summary, like other stabilizing muscles of the trunk, the multifidus contract bilaterally regardless of the direction of motion, the deep fibers are active during low-intensity tasks (static <a id="posture" data-tip="1661" target="_blank" href="/glossary-term/posture" class="glossary">postures</a>), activity increases during active <a id="posture" data-tip="1661" target="_blank" href="/glossary-term/posture" class="glossary">postures</a> and loading, and these muscles may fire before larger movers of the spine.
 The case for miscategorizing the multifidus, as under-active relative to Lumbo Pelvic Hip Complex Dysfunction (LPHCD), starts with a group of studies showing atrophy, histochemical and <a id="connective-tissue-cell" data-tip="1368" target="_blank" href="/glossary-term/connective-tissue-cell" class="glossary">connective tissue</a> changes in those exhibiting chronic low back pain. Several studies have shown that the cross-sectional area of these muscles decreases in those with chronic low back pain. The atrophy is often segment-specific and is likely to occur unilaterally in those with sided pain (111-123). Although preferential atrophy of type II fibers has been observed in some studies, it is not clear whether this is correlated with low back pain or a byproduct of surgery and/or age-related changes (122, 124-127). <a id="connective-tissue-cell" data-tip="1368" target="_blank" href="/glossary-term/connective-tissue-cell" class="glossary">connective tissue</a> changes are worthy of further investigation, as a study by Lehto et al, found fibrosis correlated with impaired ability to recover (128). Last, although not clinically <a id="relevance" data-tip="1505" target="_blank" href="/glossary-term/relevance" class="glossary">relevant</a> for human movement professionals, core-targetoid (moth-eaten) changes to type I fibers may have <a id="relevance" data-tip="1504" target="_blank" href="/glossary-term/relevance" class="glossary">relevance</a> to diagnosis and prognosis if lab tests can be made easily implantable (129). It is important that we do not confuse atrophy with under-activity, relative to our categorization for use during exercise selection. Although it may be more difficult to hypothesize a process that results in atrophy from over-activity; research and clinical findings on activity relative to dysfunction must be considered in addition to findings of atrophy.
 The activity of the multifidus is a bit complex. There are a couple of studies that imply denervation is a cause of multifidus dysfunction (125, 130); however, this does not appear to be a consistent finding (124, 129). It seems more likely that denervation is <a id="specificity" data-tip="1224" target="_blank" href="/glossary-term/specificity" class="glossary">specific</a> to surgical intervention and retrolisthesis (125, 130). In those individuals exhibiting chronic low back pain the multifidus are less active especially in lumbar extended positions (131, 132), are weaker and fatigue faster (133, 134), are more active during static standing and stabilization (135-137), peak higher during flexion, spontaneously discharge around <a id="hypermobility" data-tip="1679" target="_blank" href="/glossary-term/hypermobility" class="glossary">hypermobile</a> segments (132, 135, 137), and remain active for longer after a lift (138). Changes in motor behavior also include a &quot;decoupling&quot; of the <a id="bilateral" data-tip="1552" target="_blank" href="/glossary-term/bilateral" class="glossary">bilateral</a> contraction normally seen during lifting tasks (106, 139). <a id="trigger-point" data-tip="1632" target="_blank" href="/glossary-term/trigger-point" class="glossary">Trigger point</a> development may also be common (140-141). To summarize, <a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a> function of the multifidus is replaced with continuous low force output, <a id="unilateral" data-tip="1551" target="_blank" href="/glossary-term/unilateral" class="glossary">unilateral</a> and asymmetrical recruitment in response to stress, spasm, or high-activity with any high-intensity task or task requiring significant <a id="stability" data-tip="1191" target="_blank" href="/glossary-term/stability" class="glossary">stability</a>, and increased activity for a longer period post recruitment. This change in behavior would seem to replace an appropriately low-intensity stabilization function, with bracing and over-activity. Even the loss of force output, quicker time to fatigue, and inactivity in extended positions can be explained by adaptive shortening and altered <a id="lengthtension-relationship" data-tip="1685" target="_blank" href="/glossary-term/lengthtension-relationship" class="glossary">length/tension</a>, resulting in less efficient force output and active insufficiency in extended positions.
 <h4> Hypothesized compensation pattern of the Multifidus: </h4>
 <ol>
 <li>Low activity at all times (not quite during static <a id="posture" data-tip="1658" target="_blank" href="/glossary-term/posture" class="glossary">posture</a>)</li>
 <li>Weaker and fatigue faster</li>
 <li><a id="bilateral" data-tip="1552" target="_blank" href="/glossary-term/bilateral" class="glossary">Bilateral</a> activation replaced by directions <a id="specificity" data-tip="1224" target="_blank" href="/glossary-term/specificity" class="glossary">specific</a> <a id="unilateral" data-tip="1551" target="_blank" href="/glossary-term/unilateral" class="glossary">unilateral</a> activation</li>
 <li>Increased activity in response to load and instability</li>
 <li>Increased activity for longer after lifting</li>
 <li><a id="trigger-point" data-tip="1632" target="_blank" href="/glossary-term/trigger-point" class="glossary">Trigger point</a> development</li>
 </ol>
 Exercise has been shown to be effective for increasing multifidus cross-sectional area, although it would seem that stabilization exercises are generally more effective than loaded extension (142-143). Research by Hides et al. has shown that recovery of the multifidus is not automatic post low back pain; however, stabilization exercises are effective for both short-term reduction of symptoms and reduction of low back pain recurrence long-term (144-146). Last, it may be prudent to not &quot;wait for injury&quot;, as a study by Lee et al. demonstrated that imbalance between spine flexors and extensors was a risk factor for low back injury in a 5-year <a id="prospective-study" data-tip="1414" target="_blank" href="/glossary-term/prospective-study" class="glossary">prospective study</a> (147). Based on the <a id="compensation-pattern" data-tip="1696" target="_blank" href="/glossary-term/compensation-pattern" class="glossary">compensation pattern</a> adopted, and the stabilization exercise being more effective than <a id="specificity" data-tip="1224" target="_blank" href="/glossary-term/specificity" class="glossary">specific</a> multifidus strengthening, the Brookbush Institute recommends treating these muscles as short/over-active (<a id="release" data-tip="1249" target="_blank" href="/glossary-term/release" class="glossary">release</a> and lengthening) in those exhibiting dysfunction. However, careful attention during core <a id="integration" data-tip="1472" target="_blank" href="/glossary-term/integration" class="glossary">integration</a> exercise is also recommended; specifically using cueing to enhance <a id="bilateral" data-tip="1552" target="_blank" href="/glossary-term/bilateral" class="glossary">bilateral</a> activation during Intrinsic Stabilization Subsystem <a id="integration" data-tip="1472" target="_blank" href="/glossary-term/integration" class="glossary">integration</a>.
</div>

A comprehensive analysis of core <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> function should not exclude any muscles crossing the lumbar spine. Deep to the multifidus are several small sets of muscles fibers known as the rotatores (from spinous process to transverse process spanning 1 or 2 segments), intertransversarii (running vertically between transverse processes), and interspinales (running vertically between the spinous process). These fibers are multipennate (especially the rotatores) highly aerobic, with fibers organized in parallel, an arrangement that may be advantageous for &#x201C;fine-tuning&#x201D; of vertebral movements (148). However, McGill (12) noted that these deeper muscles are so small and have such small moment arms that is unlikely they contribute to motion.
There is evidence to suggest that the rotatores, intertransversarii, and interspinales serve a sensory function. Two studies demonstrate these muscles have a much higher <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> spindle concentration (4.5 to 7.3 times higher) than the multifidus or <a href="https://brookbushinstitute.com/courses/erector-spinae" target="_blank" rel="noopener">erector spinae </a> (149-150). Another study by Waters and Morris demonstrated that these muscles are active in conjunction with the multifidus; however, the graphs depicting EMG activity in the published paper seem to illustrate the onset of deep <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity prior to the multifidus (151). Note: the difference in onset timing of the multifidus and deep rotators was not evaluated for statistical significance. Assuming the onset timing was significant, it is plausible that the deep rotators initially respond to stretch with an increase in activity, followed by a reflexive increase in activity of the larger multifidus. Supporting this <a id="hypothesis" data-tip="1446" target="_blank" href="/glossary-term/hypothesis" class="glossary">hypothesis</a> are two studies that show the supraspinous, interspinous, and iliolumbar ligaments are abundantly innervated by Pacinian receptors and Ruffini endings (152, 153). The supraspinous and interspinous ligaments are continuations of the fascial sheath of the interspinous and intertransversarii <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> fibers. Although additional studies show that these receptors may only be stimulated at end range as limit detectors, the finding reinforces the role of these fibers as primarily sensory (154, 155).
The rotatores, intertransversarii, and interspinales are often omitted from analysis of core muscles, were not included in the original description of subsystems (which also excluded all the muscles of the ISS), and these muscles are scarcely mentioned in research and texts on the intrinsic stabilizers. The BI asserts these muscles may be viewed as a deeper set of segmental stabilizers/extensors serving a role as proprioceptors or sensory organs. More research should be designed to determine whether a feedback loop exists that results from an initial lengthening of these deep muscles and reflexive increases in <a id="tone" data-tip="1639" target="_blank" href="/glossary-term/tone" class="glossary">tone</a> of the multifidus, and perhaps a cascade that stimulates the ISS.
<img src="https://www.datocms-assets.com/25800/1648090160-1642105523-multifidi.png" title="The location and boney attachments of the multifidi of the back" alt="The attachment of the multifidi muscles in the lower back">
Modified image from Gray&apos;s Anatomy - https://en.wikipedia.org/wiki/Multifidus_muscle

There is not much research on the quadratus lumborum (QL), likely due to its location deep to other paraspinal muscles. Studies have demonstrated a moment arm too small to contribute to large amounts of force, and motion of the lumbar spine results in little change to QL length (156, 157). Lying <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> flexion and the <a href="https://brookbushinstitute.com/video/side-plank" target="_blank" rel="noopener">side plank</a> result in significant recruitment of the QL (158, 159); however, the muscle&apos;s size and short moment arm suggest it acts as a &quot;stabilizer&quot;, and not a <a id="prime-mover" data-tip="1662" target="_blank" href="/glossary-term/prime-mover" class="glossary">prime mover</a> (159). An interesting finding by McGill et al. demonstrated an increase in EMG activity with increased load during <a id="bilateral" data-tip="1552" target="_blank" href="/glossary-term/bilateral" class="glossary">bilateral</a> carrying (159), and two studies have shown that the QL is still active during the &quot;flexion-relaxation phenomenon&quot; (158, 160). The <a id="bilateral" data-tip="1552" target="_blank" href="/glossary-term/bilateral" class="glossary">bilateral</a> carrying results in comprehensive forces, which may imply the increase in QL activity is similar to that of the TVA and <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener"> internal obliques </a> in response to <a id="compression" data-tip="1595" target="_blank" href="/glossary-term/compression" class="glossary">compression</a> of the lumbar spine. Further, activity during the flexion-relaxation phenomenon is another trait of intrinsic stabilizing muscles (ISS).
To our knowledge no studies exist comparing the EMG activity of the QL in symptomatic low back pain patients to asymptomatic controls; however, two MRI studies have shown a decrease in QL cross-sectional area in those with chronic low back pain (161-162). A study by Hua et al. demonstrated good <a id="reliability" data-tip="1515" target="_blank" href="/glossary-term/reliability" class="glossary">reliability</a> for locating myofascial <a id="trigger-point" data-tip="1634" target="_blank" href="/glossary-term/trigger-point" class="glossary">trigger points</a> when matched to tenderness upon palpation and replication to patient symptoms (163), and a case study by Graber reported targeted inhibition/relaxation of the QL to resolved low back pain symptoms (164)). Activity similar to other stabilizers, development of <a id="trigger-point" data-tip="1634" target="_blank" href="/glossary-term/trigger-point" class="glossary">trigger points</a>, and atrophy in those with low back pain is similar to the behavior noted in the multifidus. It is the recommendation of the BI that the QL and multifidus are addressed as short/overactive muscles, with <a id="release" data-tip="1249" target="_blank" href="/glossary-term/release" class="glossary">release</a> techniques, lengthening techniques when necessary, and ISS (stabilization) exercises.

Quadratus Lumborum

<h3 id="gs_cit1" class="gs_citr" tabindex="0"></h3>
<div class="gs_citr" tabindex="0">
 The psoas is a hip flexor; however, it is likely not a primary hip flexor until the end of hip flexion range of motion (165, 166). This <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> is most active during activities requiring maximal effort hip flexion, and only active up to 25% of maximum voluntary isometric contraction (MVIC) during activities like <a href="https://brookbushinstitute.com/video/push-ups-and-progression" target="_blank" rel="noopener">push-ups </a> (166). Further, in a study by Anderson et al., the psoas is shown to be active during upright sitting and frontal plane stabilization of the lumbar spine when carrying a <a id="contralateral" data-tip="1549" target="_blank" href="/glossary-term/contralateral" class="glossary">contralateral</a> load, but quiet during static standing (167). The duel function of the&#xA0;psoas as a lumbar spine <a id="stabilizers" data-tip="1653" target="_blank" href="/glossary-term/stabilizers" class="glossary">stabilizer</a> and hip flexor is further highlighted by the duel <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> innervation from the femoral <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> and direct branches from the <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> rami of <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> roots L1 - L3 (168 - 170). More consideration should be given to the psoas belonging to a group of lumbar stabilizers and perhaps less to its function as a hip flexor.
 The loss of hip extension, increased lordosis and <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> pelvic tilt commonly noted in those exhibiting signs of LPHCD would suggest this <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> is short, and if over-active could contribute to these impairments (171 - 177). Further, this <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> may contribute to spinal <a id="compression" data-tip="1595" target="_blank" href="/glossary-term/compression" class="glossary">compression</a>, to a lesser degree <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> <a id="glide" data-tip="1817" target="_blank" href="/glossary-term/glide" class="glossary">shear</a> (mostly at L5, S1), and flexion of the lower lumbar spine (increased lordosis) (178-179), all of which have been implicated as contributing factors (or irritants) to a herniated nucleus pulposus (HNP) and/or <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> root impingement. This muscle&apos;s contribution to <a href="https://brookbushinstitute.com/courses/hip-joint" target="_blank" rel="noopener">hip</a> external rotation would also be worthy of exploration given the decrease in hip internal rotation associated with LPHCD (180 - 185); at this time no studies could be located. Several studies have shown atrophy of the psoas on the side of low back pain, and potentially segmentally <a id="specificity" data-tip="1224" target="_blank" href="/glossary-term/specificity" class="glossary">specific</a> atrophy corresponding to the level of HNP (186-190). There is some evidence that strength may be further affected by fatty infiltrate in the psoas post-injury, but conflicting research exists (191-192). The activity, compensation, atrophy, and morphologic change in response to low back pain of the psoas are very similar to findings for the multifidus and QL.
 Clinically, the BI notes the presence of <a id="trigger-point" data-tip="1634" target="_blank" href="/glossary-term/trigger-point" class="glossary">trigger points</a> and increased tissue density in the iliacus more often than the psoas. Findings based on palpation may be less <a id="reliability" data-tip="1795" target="_blank" href="/glossary-term/reliability" class="glossary">reliable</a> but are presented here to inspire a potential direction for research. It is the assertion of the BI that the psoas, QL, and multifidus function and <a id="compensation-pattern" data-tip="1697" target="_blank" href="/glossary-term/compensation-pattern" class="glossary">compensate</a> similarly, and should be addressed similarly with <a id="release" data-tip="1249" target="_blank" href="/glossary-term/release" class="glossary">release</a> techniques (when necessary), lengthening techniques (when necessary), and ISS (stabilization) exercises.
 <img title="The psoas and iliacus muscles attaching into the lumbar spine, pelvis, and femur" src="https://www.datocms-assets.com/25800/1647452924-1642101385-iliopsoas.jpeg" alt="Image of the psoas and iliacus muscles">
</div>

<ul>
 <li>The fascial component of this myofascial synergy may be a spherical sheath that includes the <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> and middle layers of the TLF fascia, the <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> abdominal fascia, the investing fascia of the diaphragm, and the fascia of the pelvic floor muscles.</li>
 <li>The muscles investing in this fascial sheath include the transverse abdominis (TVA), internal obliques, pelvic floor (levator ani and coccygeus), diaphragm, multifidus, rotatores, interspinales &amp; intertransversarii, and potentially the quadratus lumborum and psoas.</li>
 <li>The ISS is a stabilization subsystem that does not function in isolation, but in synergy with subsystems better suited for movement.</li>
 <li>The TVA and <a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener">internal obliques</a> enhance <a id="stability" data-tip="1191" target="_blank" href="/glossary-term/stability" class="glossary">stability</a> by increasing <a id="tension" data-tip="1229" target="_blank" href="/glossary-term/tension" class="glossary">tension</a> in the TLF, compressing the (<a id="force-closure" data-tip="1448" target="_blank" href="/glossary-term/force-closure" class="glossary">force closure</a>) SIJ, and decreasing intra-abdominal volume which may increase intra-abdominal pressure.</li>
 <li><a href="https://brookbushinstitute.com/courses/lumbo-pelvic-hip-complex-dysfunction-lphcd" target="_blank" rel="noopener"> Lumbo Pelvic Hip Complex Dysfunction (LPHCD) </a> results in a decrease in TVA and internal obliques activity.</li>
 <li>Although the internal obliques can function as the external obliques, they behave like the TVA.</li>
 <li>The diaphragm may adopt a higher average activity level and lower position in response to <a id="stability" data-tip="1191" target="_blank" href="/glossary-term/stability" class="glossary">stability</a> demands (likely contributing to an increase in intra-abdominal pressure)</li>
 <li>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.</li>
 <li>The pelvic floor muscles (PFM) are recruited with the TVA, internal obliques, and diaphragm.</li>
 <li>Contracting the PFM during ISS exercise may increase TVA activity.</li>
 <li>The multifidus function like other stabilizing muscles of the spine (including the TVA, pelvic floor, and diaphragm)</li>
 <li>The compensatory pattern adopted by the multifidus in those exhibiting dysfunction suggests a <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> that is short/over-active.</li>
 <li>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.</li>
 <li>Recovery from multifidus atrophy is best accomplished via stabilization exercise, not loaded extension.</li>
 <li>The quadratus lumborum and psoas are recruited and <a id="compensation-pattern" data-tip="1697" target="_blank" href="/glossary-term/compensation-pattern" class="glossary">compensate</a> (short/over-active) similar to the multifidus, and show the same atrophy and morphological change in those with chronic low back pain.</li>
 <li>The <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> and quadruped (<a id="stability" data-tip="1191" target="_blank" href="/glossary-term/stability" class="glossary">stability</a> exercise) are effective for enhancing the recruitment and hypertrophy of ISS muscles.</li>
</ul>
<h3>The Muscles of the ISS can be separated into 2 categories:</h3>
 Long/Under-active (Less or latent recruitment, a relative increase in length, decrease in force production, quicker to fatigue)
<ul>
 <li>Transverse abdominis (TVA)</li>
 <li><a href="https://brookbushinstitute.com/courses/internal-obliques" target="_blank" rel="noopener"> Internal obliques </a></li>
 <li>Pelvic floor (levator ani and coccygeus),</li>
 <li>Diaphragm</li>
</ul>
 Short/Over-active (Higher average activity, <a id="prone" data-tip="1561" target="_blank" href="/glossary-term/prone" class="glossary">prone</a> to spikes, higher activity level for longer after lifting, loss of <a id="bilateral" data-tip="1552" target="_blank" href="/glossary-term/bilateral" class="glossary">bilateral</a> activation in response to load, may show marked atrophy in those with chronic low back pain)
<ul>
 <li>Multifidus</li>
 <li>Rotatores, interspinales &amp; intertransversarii</li>
 <li>Quadratus lumborum</li>
 <li>Psoas</li>
</ul>
<a href="https://brookbush.s3.us-east-2.amazonaws.com/wordpress/wp-content/uploads/2016/07/Dynamic-Quadruped.png" target="_blank" rel="noopener"><img title="Dr. Brent Brookbush demonstrating a dynamic quadruped (bear crawl), which is an activation exercise for the TVA" src="https://www.datocms-assets.com/25800/1646155825-dynamic-quadruped.png" alt="Dynamic quadruped exercise being performed with a softball on the back to increase recruitment of the TVA"></a> Dynamic Quadruped

Practical Application

<div tabindex="0"> Stabilization Subsystem - The transverse abdominis (TVA), internal obliques, diaphragm, and pelvic floor muscles increase tension in the fascial sheath of the ISS, and increase intra-abdominal pressure which aids in creating a posterior to anterior force and a traction effect on the lumbar spine (24-34, 39, 69, 74-75). The multifidus, rotatores, intertransversarii, and interspinales, multifidus, quadratus lumborum, and psoas act on the lumbar spine and sacroiliac joint, aiding in as segmental stabilization by optimizing alignment and stiffness (98-101, 148, 151, 158-160, 167). Although these two groups of muscles adopt opposite compensatory patterns in response to dysfunction, when functioning optimally they share several similar traits. Muscles of the ISS have a propensity to fire prior to movement of the limbs, bilaterally in a non-direction specific manner, do not produce significant motion, and must work in synergy with other subsystems during higher intensity tasks (1-2, 10-14, 17-24, 34, 39, 66, 67, 73, 76-79, 81, 82, 91, 104-106, 148, 151). This subsystem is analogous to the rotator cuff of the shoulder; optimal function of the ISS may be essential to optimal performance of all other trunk muscles.</div>
<div tabindex="0"> Eccentric Decelerator of Flexion and compression - Although this subsystem does not contribute significantly to motion, it may aid in decelerating motion. Research shows that increased stiffness in the thoracolumbar fascia (TLF) results in increased stiffness of the lumbar spine and force closure of the sacroiliac joints (25-31). Several studies have noted the potential of the TLF to eccentrically decelerate lumbar flexion (3, 8, 9). Further, an increase in intra-abdominal pressure, increases rigidity of the spine, may decompress the spine and may resist flexion and lateral flexion torques (32-34).</div>
 Compensations and <a id="model" data-tip="1471" target="_blank" href="/glossary-term/model" class="glossary">models</a> of <a id="posture" data-tip="1659" target="_blank" href="/glossary-term/posture" class="glossary">postural</a> dysfunction - The ISS (as well as the POS) is commonly under-active. As demonstrated in the research described above, dysfunction results in the muscles listed as long/under-active having a propensity toward a decrease in activity and/or latent recruitment (21, 39- 44, 69 - 72, 78, 80, 81, 83 - 86, 94), and those muscles that are short/over-active having a propensity toward atrophy resulting in a decreased ability to produce force (111-123, 161-162, 168 - 170). This is the &quot;stability subsystem&quot;, and the function of all subsystems may be dependent on its <a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a> activity and recruitment. In the Brookbush Institute&apos;s predictive <a id="model" data-tip="1471" target="_blank" href="/glossary-term/model" class="glossary">models</a> of <a title="Upper Body Dysfunction" href="https://brookbushinstitute.com/courses/upper-body-dysfunction-ubd" target="_blank" rel="noopener"> Upper Body Dysfunction (UBD)</a>, <a href="https://brookbushinstitute.com/courses/lumbo-pelvic-hip-complex-dysfunction-lphcd" target="_blank" rel="noopener"> Lumbo Pelvic Hip Complex Dysfunction (LPHCD)</a>, Sacroiliac Joint Dysfunction (SIJD), and <a title="LLD" href="https://brookbushinstitute.com/courses/lower-leg-dysfunction" target="_blank" rel="noopener"> Lower Extremity dysfunction (LED)</a>&#xA0;this sub-system is noted as under-active. Commonly, the under-activity of the ISS results in <a id="synergistic-dominance" data-tip="1643" target="_blank" href="/glossary-term/synergistic-dominance" class="glossary">synergistic dominance</a> of the <a title="AOS" href="https://brookbushinstitute.com/courses/anterior-oblique-subsystem-aos" target="_blank" rel="noopener"> </a><a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">Anterior</a> Oblique Subsystem (AOS)<span style="display: inline !important; float: none; background-color: transparent; color: #333333; cursor: text; font-family: Georgia,&apos;Times New Roman&apos;,&apos;Bitstream Charter&apos;,Times,serif; font-size: 16px; font-style: normal; font-variant: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-decoration: none; text-indent: 0px; text-transform: none; -webkit-text-stroke-width: 0px; white-space: normal; word-spacing: 0px;">, altered <a id="reciprocal-inhibition" data-tip="1655" target="_blank" href="/glossary-term/reciprocal-inhibition" class="glossary">reciprocal inhibition</a> of the <a href="https://brookbushinstitute.com/courses/posterior-oblique-subsystem-pos" target="_blank" rel="noopener"> </a><a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">Posterior</a> Oblique Subsystem (POS), and synergistic dominance of the <a title="DLS" href="https://brookbushinstitute.com/courses/deep-longitudinal-subsystem" target="_blank" rel="noopener"> Deep Longitudinal Subsystem (DLS)</a>.

<h3>Practical Application:</h3>
Altered Activity: Based on available research on individual muscles, the Brookbush Institute&apos;s (BI&apos;s) predictive <a id="model" data-tip="1471" target="_blank" href="/glossary-term/model" class="glossary">models</a> of <a id="posture" data-tip="1659" target="_blank" href="/glossary-term/posture" class="glossary">postural</a> dysfunction, and observations in practice, this subsystem is categorized as &quot;under-active.&quot;&#xA0;As subsystems are synergies, dynamic multi-segmental <a id="posture" data-tip="1659" target="_blank" href="/glossary-term/posture" class="glossary">postural</a> <a id="assessment" data-tip="1478" target="_blank" href="/glossary-term/assessment" class="glossary">assessment</a> is recommended for determining compensatory activity, and under-activity should be addressed with multi-joint exercise. The BI uses the research and theory of subsystems as a means of refining core and <a id="integration" data-tip="1473" target="_blank" href="/glossary-term/integration" class="glossary">integrated</a> exercise selection. Note, the BI&apos;s Corrective-Template addresses individual structures prior to addressing subsystems to reduce <a id="relative-flexibility" data-tip="1654" target="_blank" href="/glossary-term/relative-flexibility" class="glossary">relative flexibility</a>, <a id="synergistic-dominance" data-tip="1643" target="_blank" href="/glossary-term/synergistic-dominance" class="glossary">synergistic dominance</a>, and compensatory patterns. 
 Assessment: The Research has demonstrated that the muscles of the ISS are recruited similarly (51 - 57, 73, 76 - 79, 81 - 82, 107-109, 151, 158-160, 167), and likely reflexively in synergy. It may be most appropriate to think of <a id="assessment" data-tip="1478" target="_blank" href="/glossary-term/assessment" class="glossary">assessment</a> and strength/stability exercise intervention for any muscles of the ISS, as <a id="assessment" data-tip="1478" target="_blank" href="/glossary-term/assessment" class="glossary">assessment</a> and exercise for all the muscles of the ISS. Most of the research on <a id="assessment" data-tip="1478" target="_blank" href="/glossary-term/assessment" class="glossary">assessment</a> and intervention is on the TVA (and internal obliques ) (49 - 61). Further, studies investigating other muscles have mentioned similar exercises like those used in TVA studies (stabilization exercise) (59-60, 83, 95-96, 142-143); and several have demonstrated better results than muscle-specific interventions (i.e. lumbar extension for multifidus strengthening) (95-96, 142-143).
<ul style="font-style: inherit; font-weight: inherit;">
 <li style="font-style: inherit; font-weight: inherit;" tabindex="0"> Abdominal <a id="drawing-in" data-tip="1580" target="_blank" href="/glossary-term/drawing-in" class="glossary">Drawing-in</a> Maneuver (<a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a>) &#x2013; A light contraction of the transverse abominis (and potentially the entire intrinsic stabilization subsystem ) is achieved by gently pulling the lower abdominal region away from one&#x2019;s waistband. This should have minimal effect on breathing, and should not be confused with a maximal contraction of the transverse abdominis resulting in a &#x201C;vacuum pose&#x201D;.</li>
</ul>
Low back pain has been shown to reduce the ability to perform the <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> (49), and conversely, the <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> has been shown to be a <a id="reliability" data-tip="1795" target="_blank" href="/glossary-term/reliability" class="glossary">reliable</a> <a id="assessment" data-tip="1478" target="_blank" href="/glossary-term/assessment" class="glossary">assessment</a> of decreased TVA function (50). That is, the inability to perform the <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> or perform the <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> without co-contraction of the <a href="https://brookbushinstitute.com/courses/rectus-abdominis-pyramidalis" style="font-style: inherit; font-weight: inherit;" target="_blank" rel="noopener">rectus abdominis</a> and <a href="https://brookbushinstitute.com/courses/external-obliques" style="font-style: inherit; font-weight: inherit;" target="_blank" rel="noopener">external obliques </a> (<a href="https://brookbushinstitute.com/courses/anterior-oblique-subsystem-aos" style="font-style: inherit; font-weight: inherit;" target="_blank" rel="noopener">Anterior Oblique Subsystem (AOS))</a>&#xA0;may be a sign of ISS dysfunction. During multi-joint/functional movement patterns, abdominal distension may be viewed as a loss of the reflexive recruitment of the ISS and the <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a>. Further, based on the correlations between low back pain, <a id="osteokinematic-motion" data-tip="1881" target="_blank" href="/glossary-term/osteokinematic-motion" class="glossary">osteokinematic</a> dysfunction, and altered recruitment patterns, signs of <a href="https://brookbushinstitute.com/courses/lumbo-pelvic-hip-complex-dysfunction-lphcd" style="font-style: inherit; font-weight: inherit;" target="_blank" rel="noopener"> Lumbo Pelvic Hip Complex Dysfunction (LPHCD) </a> may imply ISS dysfunction. This could include the following signs on the <a href="https://brookbushinstitute.com/courses/solutions-table-overhead-squat-assessment" style="font-style: inherit; font-weight: inherit;" target="_blank" rel="noopener"> Overhead Squat </a><a id="assessment" data-tip="1478" target="_blank" href="/glossary-term/assessment" class="glossary">assessment</a> (OHSA) :
<ul style="font-style: inherit; font-weight: inherit;">
 <li style="font-style: inherit; font-weight: inherit;"><a href="https://brookbushinstitute.com/video/overhead-squat-assessment-6-knees-bow-in-breakdown" style="font-style: inherit; font-weight: inherit;" target="_blank" rel="noopener"> Knees Bow In </a></li>
 <li style="font-style: inherit; font-weight: inherit;"><a href="https://brookbushinstitute.com/video/overhead-squat-assessment-7-knees-bow-out" style="font-style: inherit; font-weight: inherit;" target="_blank" rel="noopener"> Knees Bow Out </a></li>
 <li style="font-style: inherit; font-weight: inherit;"><a href="https://brookbushinstitute.com/video/overhead-squat-assessment-9-anterior-pelvic-tilt-excessive-lordosis" style="font-style: inherit; font-weight: inherit;" target="_blank" rel="noopener"> </a><a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">Anterior</a> Pelvic Tilt </li>
 <li style="font-style: inherit; font-weight: inherit;"><a href="https://brookbushinstitute.com/video/overhead-squat-assessment-8-excessive-forward-lean" style="font-style: inherit; font-weight: inherit;" target="_blank" rel="noopener"> Excessive Forward Lean </a></li>
 <li style="font-style: inherit; font-weight: inherit;"><a href="https://brookbushinstitute.com/video/overhead-squat-assessment-10-arms-fall" style="font-style: inherit; font-weight: inherit;" target="_blank" rel="noopener"> Arms Fall</a></li>
</ul>
 Core Exercise: Again, several studies have demonstrated the effectiveness of stabilization exercise for the muscles of the ISS (59-60, 83, 95-96, 142-143); and some research has demonstrated better results than muscle-specific interventions (i.e. lumbar extension for multifidus strengthening) (95-96, 142-143). Cueing the <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> has been shown to preferentially recruit the TVA, to the exclusion of more superficial muscles (<a href="https://brookbushinstitute.com/courses/rectus-abdominis-pyramidalis" style="font-style: inherit; font-weight: inherit;" target="_blank" rel="noopener">rectus abdominis</a> and <a href="https://brookbushinstitute.com/courses/external-obliques" style="font-style: inherit; font-weight: inherit;" target="_blank" rel="noopener">external obliques</a>) (51), has been shown to be effective for increasing TVA contraction during more functional tasks (52), and <a id="specificity" data-tip="1224" target="_blank" href="/glossary-term/specificity" class="glossary">specific</a> training of deep muscles results in an immediate change to recruitment strategies (53). Neutral spine, adding ankle dorsiflexion to <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> exercises, and cueing pelvic floor <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> contraction (PFM) may increase TVA activity (54-56, 95-96). Although, stabilization exercise will enhance diaphragm function, &#x201C;controlled-breath therapy&#x201D; during AIDM exercise may also be beneficial (83, 90). Quadrupeds (TVA Activation) with cueing of the <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> resulted in similar TVA activity in asymptomatic individuals and those with low back pain, which may suggest this exercise is ideal for normalizing recruitment patterns (57). Leg raises resulted in greater TVA activity; however, this exercise also sharply increased <a href="https://brookbushinstitute.com/courses/erector-spinae" style="font-style: inherit; font-weight: inherit;" target="_blank" rel="noopener">erector spinae</a> activity (a <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> <a id="prone" data-tip="1561" target="_blank" href="/glossary-term/prone" class="glossary">prone</a> to over-activity) (58). Correlations have been made between TVA thickness, lumbar <a id="stability" data-tip="1191" target="_blank" href="/glossary-term/stability" class="glossary">stability</a>, and <a id="balance" data-tip="1190" target="_blank" href="/glossary-term/balance" class="glossary">balance</a>, which may have implications for injury prevention and sports performance (61). Cueing the <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> during functional activities, and quadrupeds <a id="exercise-progression" data-tip="1182" target="_blank" href="/glossary-term/exercise-progression" class="glossary">progressions</a> (with the additional cues noted above) with <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> for &quot;core integration&quot; techniques are the ISS <a id="specificity" data-tip="1224" target="_blank" href="/glossary-term/specificity" class="glossary">specific</a> interventions recommended by the Brookbush Institute. Additional Cues:
<ul style="font-style: inherit; font-weight: inherit;">
 <li style="font-style: inherit; font-weight: inherit;">Neutral Spine</li>
 <li style="font-style: inherit; font-weight: inherit;">Dorsiflexion</li>
 <li style="font-style: inherit; font-weight: inherit;">Pelvic Floor Contraction</li>
 <li style="font-style: inherit; font-weight: inherit;">Controlled Breathing</li>
</ul>
 <a id="integration" data-tip="1473" target="_blank" href="/glossary-term/integration" class="glossary">Integrated</a> Exercise: As the ISS does not include muscles that cross the hip or shoulder girdle (the psoas being an exception), there are no <a id="integration" data-tip="1473" target="_blank" href="/glossary-term/integration" class="glossary">Integrated</a> Exercises <a id="specificity" data-tip="1224" target="_blank" href="/glossary-term/specificity" class="glossary">specific</a> to the ISS. However, the <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> should be cued during all <a id="integration" data-tip="1473" target="_blank" href="/glossary-term/integration" class="glossary">Integrated</a> exercises. 
 Instrument-Assisted Soft Tissue Mobilization (IASTM) of the TLF: Fascia&apos;s response to <a id="specificity" data-tip="1224" target="_blank" href="/glossary-term/specificity" class="glossary">specific</a> intervention is complex. Responses may include strain hardening with repetitive or constant <a id="tension" data-tip="1229" target="_blank" href="/glossary-term/tension" class="glossary">tension</a>, enhanced <a id="glide" data-tip="1817" target="_blank" href="/glossary-term/glide" class="glossary">shear</a> and a reduction in cross-bridging between fascial layers, changes in both <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> <a id="tone" data-tip="1639" target="_blank" href="/glossary-term/tone" class="glossary">tone</a> and fibroblast mediated pre-tension (with sustained pressure), and/or altered transmission of force of multiple muscles acting to stabilize a joint (195-197). A study by Levangin et al. demonstrated that a chronic low back pain group showed approximately 20% less <a id="glide" data-tip="1817" target="_blank" href="/glossary-term/glide" class="glossary">shear</a> strain between layers of TLF tissues than asymptotic controls (194). These findings may suggest that techniques with the potential to improve <a id="glide" data-tip="1817" target="_blank" href="/glossary-term/glide" class="glossary">shear</a> between the <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> layer of the <a href="https://brookbushinstitute.com/courses/posterior-oblique-subsystem-pos" style="font-style: inherit; font-weight: inherit;" target="_blank" rel="noopener"> POS </a> and the <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> and middle layers of the <a href="https://brookbushinstitute.com/courses/anterior-oblique-subsystem-aos" style="font-style: inherit; font-weight: inherit;" target="_blank" rel="noopener"> AOS </a> and ISS may be worth attempting. IASTM is hypothesized to improve <a id="glide" data-tip="1818" target="_blank" href="/glossary-term/glide" class="glossary">shearing</a>, although research does not currently exist to <a id="base-of-support" data-tip="1197" target="_blank" href="/glossary-term/base-of-support" class="glossary">support</a> or refute this claim. <a id="assessment" data-tip="1478" target="_blank" href="/glossary-term/assessment" class="glossary">Assessment</a>, intervention, and careful re-assessment is recommended (as with all techniques) to determine efficacy on an individual basis. The BI has noted that IASTM of the TLF may not have a large impact on the <a href="https://brookbushinstitute.com/courses/solutions-table-overhead-squat-assessment" style="font-style: inherit; font-weight: inherit;" target="_blank" rel="noopener"> OHSA</a>, but may be generally effective for improving lumbar flexion, extension, and rotation range of motion. Care should be taken in addressing these tissues directly, as there is evidence to suggest that the TLF could be a source of nociceptive input for those suffering from chronic low back pain (196-201).

<h3>Subsystems Summary:</h3>
<table>
 <tbody>
 <tr>
 <td width="151"> Subsystem </td>
 <td width="216"> Common Behavior </td>
 <td width="151"> Core </td>
 <td width="133"> Integration </td>
 </tr>
 <tr>
 <td width="151">Intrinsic Stabilization Subsystem (ISS)
 
 
 </td>
 <td width="216">Under-active</td>
 <td width="151"><a href="https://brookbushinstitute.com/courses/transverse-abdominis-activation-quadrupeds-progressions"> Transverse Abdominis (TVA) Activation </a></td>
 <td width="133">N/A</td>
 </tr>
 <tr>
 <td width="151"><a href="https://brookbushinstitute.com/courses/anterior-oblique-subsystem-aos" target="_blank" rel="noopener"> Anterior Oblique Subsystem (AOS) </a></td>
 <td width="216">Over-active</td>
 <td width="151">
 <a href="https://brookbushinstitute.com/courses/axe-chop-progression" target="_blank" style="letter-spacing: 0px;" rel="noopener">Chop Progression</a>
 
 Avoid: planks, crunches, resisted hip flexion
 </td>
 <td width="133">Legs with Push</td>
 </tr>
 <tr>
 <td width="151"><a href="https://brookbushinstitute.com/courses/posterior-oblique-subsystem-pos" target="_blank" rel="noopener"> Posterior Oblique Subsystem (POS) </a>
 
 
 </td>
 <td width="216">Under-active</td>
 <td width="151"><a href="https://brookbushinstitute.com/courses/axe-chop-progression" target="_blank" rel="noopener"> Chop Progression </a> and <a href="https://brookbushinstitute.com/courses/bridge-progression" target="_blank" rel="noopener"> Bridge Progression </a></td>
 <td width="133">Legs with Pull</td>
 </tr>
 <tr>
 <td width="151"><a href="https://brookbushinstitute.com/courses/deep-longitudinal-subsystem" target="_blank" rel="noopener"> Deep Longitudinal Subsystem (DLS) </a></td>
 <td width="216">Over-active</td>
 <td width="151">Avoid: leg curls, lumbar extensions</td>
 <td width="133">Avoid: straight-leg deadlifts, kettlebell windmills, Nordic curls</td>
 </tr>
 </tbody>
</table>
<h3> Signs of ISS Under-activity </h3>
<ul>
 <li>
 <h4>Abdominal <a id="drawing-in" data-tip="1580" target="_blank" href="/glossary-term/drawing-in" class="glossary">Drawing-in</a> Maneuver (<a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a>)</h4>
 <ul>
 <li>Inability to perform the Abdominal <a id="drawing-in" data-tip="1580" target="_blank" href="/glossary-term/drawing-in" class="glossary">Drawing-in</a> Maneuver (<a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a>)</li>
 <li>Inability to perform the <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> without co-contraction of the <a href="https://brookbushinstitute.com/courses/rectus-abdominis-pyramidalis" target="_blank" rel="noopener"> rectus abdominis </a> and <a href="https://brookbushinstitute.com/courses/external-obliques" target="_blank" rel="noopener"> external obliques </a></li>
 <li>Abdominal distension during functional activities</li>
 </ul>
 </li>
 <li> Overhead Squat <a id="assessment" data-tip="1478" target="_blank" href="/glossary-term/assessment" class="glossary">Assessment</a> 
 <ul>
 <li><a href="https://brookbushinstitute.com/video/overhead-squat-assessment-6-knees-bow-in-breakdown" target="_blank" rel="noopener"> Knees Bow In </a></li>
 <li><a href="https://brookbushinstitute.com/video/overhead-squat-assessment-7-knees-bow-out" target="_blank" rel="noopener"> Knees Bow Out </a></li>
 <li><a href="https://brookbushinstitute.com/video/overhead-squat-assessment-9-anterior-pelvic-tilt-excessive-lordosis" target="_blank" rel="noopener"> </a><a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">Anterior</a> Pelvic Tilt </li>
 <li><a href="https://brookbushinstitute.com/video/overhead-squat-assessment-8-excessive-forward-lean" target="_blank" rel="noopener"> Excessive Forward Lean</a></li>
 <li><a href="https://brookbushinstitute.com/video/overhead-squat-assessment-15-sign-clusters-asymmetrical-weight-shift/" target="_blank" rel="noopener">Asymmetrical Weight Shift</a></li>
 <li><a href="https://brookbushinstitute.com/video/overhead-squat-assessment-10-arms-fall" target="_blank" rel="noopener"> Arms Fall</a></li>
 </ul>
 </li>
</ul>
<h3> Practical Application </h3>
<ul>
 <li> Core 
 <ul>
 <li><a href="https://brookbushinstitute.com/courses/transverse-abdominis-activation-quadrupeds-progressions" target="_blank" rel="noopener"> Quadruped Progression</a></li>
 </ul>
 </li>
</ul>
<hr>
<h3>Note: These exercises are also covered in the course: <a href="https://brookbushinstitute.com/courses/transverse-abdominis-activation-quadrupeds-progressions" target="_blank" rel="noopener"> Transverse Abdominis (TVA) Activation (Quadrupeds and Progressions) </a></h3>
<h3>Optimal Form:</h3>
<a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">Optimal</a> <a id="posture" data-tip="1660" target="_blank" href="/glossary-term/posture" class="glossary">form</a> for any exercise should be modeled with the intent of reducing signs that have been correlated with an increased risk of future pain and/or injury (e.g. absence of forward head, knees bow in, etc.). Generally, this results in cues that focus on the alignment of joints.
<ul>
 <li>Cervical and thoracic spine neutral</li>
 <li>Scapula protracted and depressed</li>
 <li>Neutral lumbar spine with abdominal <a id="drawing-in" data-tip="1580" target="_blank" href="/glossary-term/drawing-in" class="glossary">drawing-in</a> maneuver (<a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a>)</li>
 <li>Neutral pelvis (no <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> pelvic tilt)
 <ul>
 <li>Cueing a <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> pelvic tilt may be appropriate</li>
 </ul>
 </li>
 <li>Hips, knees, and ankles in alignment</li>
 <li>Ankles dorsiflexed</li>
</ul>
<h4> Notes on Form: </h4>
The exercises below differ from many of the other exercises recommended for activation and core <a id="integration" data-tip="1472" target="_blank" href="/glossary-term/integration" class="glossary">integration</a>. Although resistance is commonly used to progress exercise, the <a id="exercise-progression" data-tip="1182" target="_blank" href="/glossary-term/exercise-progression" class="glossary">progressions</a> below challenge one&apos;s ability to maintain <a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a> <a id="posture" data-tip="1660" target="_blank" href="/glossary-term/posture" class="glossary">form</a> during increasingly less stable <a id="exercise-progression" data-tip="1182" target="_blank" href="/glossary-term/exercise-progression" class="glossary">progressions</a>. During all <a id="exercise-progression" data-tip="1182" target="_blank" href="/glossary-term/exercise-progression" class="glossary">progressions</a>, the goal is to maintain the abdominal <a id="drawing-in" data-tip="1580" target="_blank" href="/glossary-term/drawing-in" class="glossary">drawing-in</a> maneuver (<a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a>), maintain the spine and pelvic position, and challenge <a id="stability" data-tip="1191" target="_blank" href="/glossary-term/stability" class="glossary">stability</a> and endurance
<ul>
 <li>Abdominal <a id="drawing-in" data-tip="1580" target="_blank" href="/glossary-term/drawing-in" class="glossary">Drawing-in</a> Maneuver (<a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a>) - a light contraction of the TVA, achieved by gently pulling the lower abdominal region away from one&apos;s waistband. This should have minimal impact on breathing, should not be confused with a &quot;vacuum pose&quot; (maximal contraction of the TVA resulting in a &quot;vacuum pose&quot;, and is not a rectus abdominis contraction. Contracting the rectus abdominis generally results in a <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> tilt of the pelvis, flexion of the lumbar spine, or flexion of the thoracic spine. If these movements are noted while performing the exercises below, re-establish <a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a> pelvic and lumbar spine position and attempt the <a id="drawing-in" data-tip="1588" target="_blank" href="/glossary-term/drawing-in" class="glossary">ADIM</a> again.</li>
</ul>

Best-use and Progressions

Activation Progressions for the Intrinsic Stabilization Subsystem

<h3>Quadruped Progressions: </h3>
<ol>
 <li>Quadruped</li>
 <li>Quadruped arm raise</li>
 <li>Quadruped opposite arm/leg raise</li>
 <li>Quadruped leg raise</li>
 <li>Dynamic Quadruped
 <ul>
 <li>Sagittal</li>
 <li>Frontal</li>
 <li>Transverse</li>
 <li>Resisted
 <ul>
 <li>Alternate Progressions: Gamification (&quot;Simon Says&quot;)</li>
 <li>Alternate Progression: Gali-peds</li>
 <li>Alternate Progression: Quadruped with Glute Activation</li>
 <li>Alternate Progression: Quadruped with Ball Resisted Cervical Retraction</li>
 <li>Alternate Progression: Hardest Quadruped <a id="exercise-progression" data-tip="1184" target="_blank" href="/glossary-term/exercise-progression" class="glossary">Progression</a> Ever</li>
 </ul>
 </li>
 </ul>
 </li>
</ol>

Isolated Activations

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

<ol>
 <li>Crunch and Catch &#x2013; Chest Pass on Floor</li>
 <li>Crunch and Catch &#x2013; Soccer Throw on Floor</li>
 <li>Crunch and Catch &#x2013; <a id="unilateral" data-tip="1551" target="_blank" href="/glossary-term/unilateral" class="glossary">unilateral</a> &#x201C;Baseball throw&#x201D; on Floor</li>
 <li>Crunch and Catch &#x2013; Chest Pass on Bosu</li>
 <li>Crunch and Catch &#x2013; Soccer Throw on Bosu</li>
 <li>Crunch and Catch &#x2013; <a id="unilateral" data-tip="1551" target="_blank" href="/glossary-term/unilateral" class="glossary">unilateral</a> &#x201C;Baseball throw&#x201D; on Bosu</li>
 <li>Crunch and Catch &#x2013; Chest Pass on Ball</li>
 <li>Crunch and Catch &#x2013; Soccer Throw on Ball</li>
 <li>Crunch and Catch &#x2013; <a id="unilateral" data-tip="1551" target="_blank" href="/glossary-term/unilateral" class="glossary">unilateral</a> &#x201C;Baseball throw on Ball</li>
</ol>

Reactive Activation Progressions

Crunch and Catch

Crunch and Catch Progressions

Bibliography

© 2018 Brent Brookbush


 Questions, comments, and criticisms are welcomed and encouraged

Copyright

A-Band - Refers to the part of the muscle cell that looks darker under a microscope.  This area of the cell is darker due to parallel arrangement of thicker filaments (myosin) and overlap with the thinner filaments (actin).
<ul>
 	<li>As a muscle contracts, the A-band is where actin and myosin interact.</li>
</ul>
<ol>
 	<li>Saladin, K. (2014). Anatomy &amp; physiology: The unity of form and function. McGraw-Hill Higher Education, New York. ISBN: 9780073403717</li>
</ol>

Accuracy - the proportion of individuals correctly identified by the test results.
<ul>
 	<li>For example, a special test with perfect accuracy would imply a test has 100% specificity, 100% sensitivity, 100% positive predictive value and 100% negative predictive values.</li>
</ul>

Action Potential - A rapid change in voltage, resulting in a wave of excitation, that may result in stimulation of a nerve or muscle cell.
<ul>
 	<li>In order for an action potential to be initiated, the resting membrane voltage must exceed the excitation threshold, which then results in a cascade of depolarization and the "wave of excitation." Any stimulus below that threshold will not result in an action potential, and a stimulus greater than the threshold will not increase a single action potential, but may result in additional action potentials.  In this way, the action potential functions more like an on/off switch (all or none), and less like a dimmer switch.</li>
</ul>

A single-joint movement pattern (most often) designed to load a specific under-active muscle(s), while minimizing the contribution of over-active synergists via specific cues/joint motions.
<ul>
 	<li style="text-align: left;">Activation techniques/exercises are performed with the intent of addressing a muscle exhibiting a reduction in activity (tone) as a result of, or contributing to postural dysfunction.</li>
 	<li style="text-align: left;">Activation techniques/exercises cannot be multi-joint movement patterns due to relative flexibility, altered reciprocal inhibition, and synergistic dominance resulting in compensation patterns.</li>
</ul>
Example, <a href="https://brentbrookbush.com/articles/corrective-exercise-articles/activation/gluteus-medius-activation-progression/" target="_blank">gluteus medius activation</a> involves resisted hip abduction while minimizing the contribution of the TFL via hip extension.

Active stretching is a term used to describe a stretch that involves an active contraction of opposing musculature to lengthen a muscle to its end range. Generally these stretches are held for 2-5 seconds and repeated for 8-15 repetitions.

Adenosine triphosphatase (ATPase): is the enzyme responsible for catalyzing (initiating and accelerating) the decomposition of ATP to ADP.
<ul>
 	<li>This dephosphorylation (breakdown) reaction releases energy for processes like muscular contraction.</li>
</ul>

Adenosine triphosphate (ATP): The molecule that functions as a universal energy-transfer molecule, providing most of the energy associated with muscular contraction and human movement. ATP is composed of an adenine group, a ribose group, and three molecules of inorganic phosphates.
<ul>
 	<li>Energy is provided when hydrolysis results in the cleaving of a phophate group; resulting in adenosine diphosphate, an inorganigic phosphate group, and energy.</li>
</ul>

Algometry - measuring the amount of pressure to result in sensitivity or pain, using an algometer.
<ul>
 	<li>Generally, research uses algometry to establish a minimum pain pressure threshold (PPT), in which a lower PPT implies more sensitivity and pain, and a higher PPT implies less sensitivity and pain. PPT is a common outcome measure in trigger point research.</li>
</ul>
<a href="https://brentbrookbush.com/wp-content/uploads/2019/07/Algometer.jpg"><img class="aligncenter wp-image-140177" src="https://brentbrookbush.com/wp-content/uploads/2019/07/Algometer.jpg" alt="Image of an Algometer" width="500" height="333" /></a>

All-or-none principle - a nerve or muscle cell's response to a stimulus is independent of the strength of the stimulus. If that stimulus exceeds the threshold potential (threshold of an action potential), the nerve or muscle fiber will respond completely; otherwise, there is no response.

Example, when a motor unit in the biceps brachii is stimulated it contracts the same way whether a 10 lb or 50 lb dumbbell is lifted.  It is actually the number of muscle cells and the size of the motor unit that determines force output.

&nbsp;

The transition period between eccentric load and concentric contraction during a repetition of an exercise.  This term is most often used in reference to power/plyometric exercises, in which a shorter amortization phase is believed to be beneficial.  The shorter amortization phase may better use the stored energy from the elastic deformation of connective tissue and enhance synchronization of myotatic (stretch) reflex with maximum voluntary contraction.

Example, the athlete was cued to spend as little time as possible in the bottom of their squat stance (the amortization phase) during a set of box jumps.

Muscles that oppose the prime mover and synergists for a given joint action.

That is, all the muscles that can perform the opposing joint action.

Example: The triceps and anconeus are antagonists during elbow flexion.

An anatomical direction; toward the front

Example, the face is on the anterior aspect of the head

Appendicular Skeleton - referring to the bones the bones of the arms and legs, as well as the bones that support them. This includes the pelvis, clavicle and scapula. There are approximately 126 bones in the appendicular skeleton.
<ul>
 	<li>Etymology - Appendicular, as in appendage, "that which is appended to something as a proper part," 1640s, from <a class="crossreference" href="https://www.etymonline.com/word/append?ref=etymonline_crossreference">append</a> + <a class="crossreference" href="https://www.etymonline.com/word/-age?ref=etymonline_crossreference">-age</a>. - <a href="https://www.etymonline.com/word/appendage" target="_blank" rel="noopener">Etymology Online</a></li>
</ul>
"Appendicular skeleton" is a label referring to a set of bones whose function is distinct from the bones of the "<a href="https://brentbrookbush.com/glossary/axial-skeleton/" target="_blank" rel="noopener">axial skeleton</a>".

A reflexive decrease in muscle activity due to joint dyskinesis.
For example, a reduction in deep cervical flexor activity as a result of cervical spine dyskinesis.

Arthrokinematic Motion - Small amplitude motions between bone surfaces at a joint.  The arthrokinematic motions are roll, glide (slide or translation), spin, compression and distraction (traction). Arthrokinematic motions accompany osteokinematic motions to maintain joint congruence.
<ul>
 	<li>Example, arthrokinematic motion of the talus includes posterior glide on the tibia during ankle dorsiflexion.</li>
</ul>
Synonyms include: arthrokinematics, passive accessory motion, joint play and component motion

&nbsp;

Assessment - is the act of assessing, i.e. determining the importance, size, or value of -

In most cases, the results of an assessment are compared to normative data. If the individual exhibits values that are within normal parameters, it may be assumed that the aspect of health or motion assessed is not contributing to the patient's complaint, symptoms or movement impairment. If the results fall outside of normal parameters, it may indicate that the aspect of health or motion assessed is contributing to, or being affected by the patient/client's complaint, symptoms, or movement impairment. In some cases, the results of an assessment are compared to an "ideal model." In this case, deviations from the ideal are noted as potential issues. For example, deviations noted in the <a title="Introduction to the Overhead Squat Assessment" href="https://brentbrookbush.com/online-courses/articles/assessment/introduction-overhead-squat-assessment/" target="_blank">Overhead Squat Assessment</a> are compared to an "ideal model" of posture and motion.

Assessments used by human movement professionals can be divided into three broad categories:
<ul>
 	<li>"Clear" the Patient/Client for Intervention - These are tests, assessments and evaluations used to determine if a patient/client's issue may improve given the assessing professional's scope, skills, abilities and willingness to treat that individual.
<ul>
 	<li>For example, many of the special tests used in orthopedic medicine assist in determining the level of pathology or likelihood of a particular diagnosis. Certain issues and diagnoses are beyond the scope of the human movement professional, and are better treated by diagnostic professionals in the medical community (physicians, podiatrists, surgeons, etc.). A Calf Squeeze (Thompson) Test is one example, in which a positive sign may indicate a rupture of the Achilles tendon that may be better treated via surgical intervention.</li>
</ul>
</li>
 	<li>Highlight Contraindications - Tests, assessments and evaluations used to stratify risk or preclude a professional from addressing certain tissues, motions or using a particular technique.
<ul>
 	<li>For example, the Vertebral Artery Test (VBI) is often used to determine if high velocity thrust mobilizations (manipulations) are safe for a patient with cervical dysfunction.</li>
</ul>
</li>
 	<li>Refine Exercise/Intervention Selection: Tests, assessments and evaluations used to assist the professional in determining which techniques, modalities and exercises will best address a patient/client's complaints or desired goals.
<ul>
 	<li>Most movement assessments fall into this category. For example, a positive <a href="https://brentbrookbush.com/vimeo_videos/elys-test-rectus-femoris-flexibility-assessment/" target="_blank">Ely's Test</a> may indicate a need to release and/or lengthen the <a href="https://brentbrookbush.com/articles/anatomy-articles/muscular-anatomy/rectus-femoris/" target="_blank">rectus femoris</a>.</li>
</ul>
</li>
</ul>
Note: An assessment, or assessment result, may fall into more than one category. For example, although goniometry is an assessment most often used to Refine Exercise/Intervention Selection, if a range of motion is significantly altered, with an abnormal end-feel, and/or causes the patient or client/pain, the individual may need to be referred to a physician for further testing and Clearance to resume rehab activities.  Further, that same patient may return to the human movement professional with a list of Contraindicated Activities from the physician. - "When in doubt, refer out!"

Axial Skeleton - referring to the bones of the head, neck, trunk and spinal column (does not include pelvis). There are approximately 80 bones in the axial skeleton.
<ul>
 	<li>Etymology - Axial, as in "axis", referring to "imaginary motionless straight line around which a body (such as the Earth) rotates," from Latin axis "axle, pivot, axis of the earth or sky" - <a href="https://www.etymonline.com/word/axis" target="_blank" rel="noopener">Etymology Online</a></li>
</ul>
"Axial skeleton" is a label referring to a set of bones whose function is distinct from the bones of the "<a href="https://brentbrookbush.com/glossary/appendicular-skeleton/" target="_blank" rel="noopener">appendicular skeleton</a>".

Balance - The ability to maintain a body’s center of mass over its base of support. Balance can be static or dynamic.
<ul>
 	<li>For example, maintaining balance is harder on one leg because the center of mass must stay over a much smaller base of support.</li>
</ul>

A ball and socket joint (also called a spheroid joint or spheroidal joint) is a synovial joint in which the rounded or spherical end of one bone fits into a cup-like depression of another bone. The distal bone is capable of motion around an indefinite number of axes, which have one common center. Examples include the hip and shoulder (glenohumeral joint)

Base of support (BoS) - refers to the area beneath an object or person, and the area within the perimeter created by every point of contact that the object or person makes with the supporting surface. This may include the <a href="https://brentbrookbush.com/articles/anatomy-articles/muscular-anatomy/gluteus-maximus/" target="_blank" rel="noopener">glutes</a> of someone sitting on a chair, or the back of someone leaning against a wall.
<ul>
 	<li>For example, during a single leg balance the BoS is the area of the foot in contact with the surface; however, when a person is standing on two feet, the BoS is the area of both feet and the surface between them.</li>
</ul>

Pertaining to both sides

Example, bilateral rows are performed with both arms at the same time.

Case-control Study - a particular form of retrospective study that samples a matched group of people who have, and do not have the outcome being studied. A case-control study is a quasi-experimental design, often used in medicine to aid in determining potential contributing factors (cannot determine causality). In this study type exposure is the dependent variable and outcome is independent.
<ul>
 	<li>Example, in this retrospective case-control, medical records were investigated for trends correlated with cervical pain (1).
<ol>
 	<li>Mäkela, M., Heliövaara, M., Sievers, K., Impivaara, O., Knekt, P., &amp; Aromaa, A. (1991). Prevalence, determinants, and consequences of chronic neck pain in Finland. American journal of epidemiology, 134(11), 1356-1367.</li>
</ol>
</li>
</ul>

An anatomical direction; toward the tail, relative to humans this term is often used to refer to "in the direction of the tale (toward the feet)".

Example, to release the trapezius muscle the therapist used a force directed caudally.

Center of mass (CoM) - an object's mean position of mass; that is, a point that is perfectly surrounded by an equal amount mass in all directions.

Center of gravity (CoG) - point where gravity appears to act. Since the human body is so small compared to the earth, we can assume gravity acts uniformly on the body, and that CoG and CoM are the same.
<ul>
 	<li>Example, the CoM of the human body while lying down or standing straight up is close to our navel. However, it is possible that during a resistance exercise, the combination of the body's weight and the weight of the resistance will place the combined CoM outside the body. For example, during the mid-portion of a <a href="https://brentbrookbush.com/vimeo_videos/back-squat/" target="_blank" rel="noopener">back squat</a> the CoM would be several anterior to the naval.</li>
</ul>

An anatomical direction; toward the head (synonym: cranial)

Example, hip pain was felt with any force directed cephalad.

Cohort Study - a particular form of longitudinal study that samples a cohort (a group of people who share a defining characteristic), performing a cross-section at intervals through-out a period of time. A cohort study is a quasi-experimental design often used in medicine to aid in determining etiology or a cause-and-effect relationship. In this study type exposure is the independent variable and outcome is dependent.
<ul>
 	<li>Example, the study by Cholewicki et al. (1) investigated Yale Varsity Athletes (the cohort) with 2 and 3 year follow up (longitudinal design) and found that trunk muscle response time to off-loading was predictive of future low back injury.</li>
</ul>
<ol>
 	<li><a href="https://brentbrookbush.com/articles/research-corner/core/increased-trunk-muscle-latency-may-cause-rather-than-result-from-low-back-pain/" target="_blank" rel="noopener noreferrer">Cholewicki, J., Silfies, S., Shah, R., Greene, H., Reeves, N. Alvi, K., Goldberg, B. (2005). Delayed trunk muscle reflex responses increase the risk of low back injuries. Spine. 30(23), 2614-2620</a></li>
</ol>

Comparable Sign: A combination of pain, stiffness and/or spasm during examination that is comparable to the patients symptoms.
<ul>
 	<li>One common error made during evaluation with special tests is attention given to any discomfort or pain, rather than attempting to identify the pain/discomfort related to the patient's complaint (concordant/comparable sign). Many special tests purposefully test tissue limits and are at least mildly uncomfortable in every individual. Basing your assessment on positive tests that resulted in "concordant/comparable signs" will improve your chances of arriving at the correct diagnosis.</li>
</ul>

An alternative movement pattern that has been adopted to compensate for dysfunction/impairment in the human movement system.
Example: A lack of calf extensibility may limit dorsiflexion, leading to the knees bowing inward (functional valgus) and excessive forward lean of the torso during a squat.

An arthrokinematic motion - the approximation of joint surfaces; that is, a force that directs one bone surface into another resulting in a reduction in intra-articular volume. Although widely thought of as a "destructive force", it is likely best to consider compression as a naturally occurring, stabilizing force. Any arthrokinematic force in excess (spin, glide, roll, traction) may be viewed as potentially deleterious.

For example, during a squat the femoral head is compressed into the acetabulum by muscular forces, bodyweight and any additional external load.

Concave (Concavity) - Having an outline or surface curved like the interior surface of a bowl or sphere - to cave-in or curve inward.
<ul>
 	<li>Example, the internal surfaces of the pelvis is concave, holding some of the bodies viscera.</li>
</ul>

Concordant Sign - The patient's specific pain, symptom or complaint. 
<ul>
 	<li>One common error made during evaluation with special tests is attention given to any discomfort or pain, rather than attempting to identify the pain/discomfort related to the patient's complaint (concordant/comparable sign). Many special tests purposefully test tissue limits and are at least mildly uncomfortable in every individual. Basing your assessment on positive tests that resulted in "concordant/comparable signs" will improve your chances of arriving at the correct diagnosis.</li>
</ul>

Conductivity: Stimulation results in more than a local effect (1).
<ul>
 	<li>For example, in a muscle cell the stimulation of a motor endplate results in a change in cell membrane polarity that rapidly propagates (is conducted) along the entire length of the muscle cell, stimulating all sacromere.</li>
</ul>
<ol>
 	<li>Saladin, K. (2012). Anatomy &amp; Physiology: The unity of form and function. (6th ed.). New York: McGraw-Hill.</li>
</ol>

A condyloid joint (also called condylar, bicondylar, ellipsoid, or ellipsoidal) is an ovoid articular surface, or condyle, that is received into an elliptical cavity.  These joints permit movement in two planes.  Examples include the knee, metacarpophalangeal joints and metatarsophalangeal joints.

Connective Tissue Cell - One of the four basic types of animal tissue, consisting mostly fibers and ground substance.  These cells are specialized to binds organs together, holds them in place, protect them from external forces, and may fill space in the body's cavities.

Example, the body's muscles are enclosed in durable connective tissue sheets known as the "epimysium", "perimysium", and "endomysium," which and in support and transmitting force.
<ol>
 	<li>Saladin, K. (2014). Anatomy &amp; physiology: The unity of form and function. McGraw-Hill Higher Education, New York. ISBN: 9780073403717</li>
</ol>

Contractility: The ability to shorten (1).
<ul>
 	<li>Contractility: Muscle cells are unique in the amount they can shorten when stimulated; this is this largerly due to the highly organized and unique arrangement of myofilaments (actin and myosin).</li>
</ul>
<ol>
 	<li>Saladin, K. (2012). Anatomy &amp; Physiology: The unity of form and function. (6th ed.). New York: McGraw-Hill.</li>
</ol>

Pertaining to the opposite side

Example, the external oblique muscle performs contralateral rotation; rotation to the opposite side.

Convex (Convexity) - Having an outline or surface curved like the exterior of a circle or sphere - to bulge or curve outward.
<ul>
 	<li>Example, the top of your head is shaped by the convex exterior surface of your skull.</li>
</ul>

Correlational Research - Non-experimental <a href="https://www.questionpro.com/blog/what-is-research/">research</a> method in which the statistical relationship between two variables is investigated.
<ul>
 	<li>In this research by Kwon et al., a correlation was noted between a decrease in extensibility during a hamstring length test (goniometry) and current knee pain (1).</li>
</ul>
<ol>
 	<li><a href="https://brentbrookbush.com/articles/research-corner/knee/correlation-patellofemoral-pain-syndrome-pfps-hamstring-activity/" target="_blank" rel="noopener">Kwon O, Yun M, and Lee W. (2014). Correlation between intrinsic patellofemoral pain syndrome in young adults and lower extremity biomechanics. J. Phys. Ther. Sci. 26: 961-964</a></li>
</ol>

Counter-nutation - posterior rotation of sacrum relative to ilium, and/or anterior rotation of ilium relative to sacrum.
<ul>
 	<li>The pelvic floor muscles are examples of muscle that may counter-nutate the sacrum.</li>
</ul>
[caption id="attachment_126335" align="aligncenter" width="400"]<a href="https://brentbrookbush.com/wp-content/uploads/2018/10/Nutation.png"><img class=" wp-image-126335" src="https://brentbrookbush.com/wp-content/uploads/2018/10/Nutation.png" alt="Nutation and Counter-nutation of the Sacroiliac Joint" width="400" height="967" /></a> Nutation and Counter-nutation of the Sacroiliac Joint[/caption]

&nbsp;

Crossover (Study) Design - A type of longitudinal, repeated measures quasi-experimental design in which each group receives both treatments, but at different times. It is named "crossover" due to the patients "crossing-over" to the other treatment or sham group after a specified period of time.
<ul>
 	<li>This type of study has the advantage of every individual serving as their own control, which may reduce the influence of confounding variables.</li>
 	<li>Unfortunately, the design itself introduces the chances that anyone receiving the experimental variable in the first period will continue to be effected in the second period.</li>
</ul>
In a study by Senna et al., a cross-over design was used to investigate the difference load made on inter-set rest intervals (1).
<ol>
 	<li><a href="https://brentbrookbush.com/articles/research-corner/strength-training-research-corner/heavy-vs-light-load-single-joint-exercise-performance-with-different-rest-periods/" target="_blank" rel="noopener">Senna, G.W., Rodrigues, B.M., Sandy, Scudese, Bianco, A, &amp; Dantas, E.H.M. (2017). Heavy vs light load single-joint exercise performance with different intervals. Journal of Human Kinetics, 58, 197-206. </a></li>
</ol>

Cross-sectional Study - a research design that involves gathering data from a population or representative subset at a specific point in time.
<ul>
 	<li>Example, the study by Karimi-Mobarake et al.(1) investigated the prevalence of genu varum and genu valgum among school children 7-11 years old in Iran.</li>
</ul>
<ol>
 	<li><a href="https://brentbrookbush.com/articles/research-corner/knee/low-prevalence-of-genu-varum-and-valgum-among-elementary-school-children/" target="_blank" rel="noopener noreferrer">Karimi-Mobarake, M., Kashefipour, A., Yousfnejad, Z. The prevalence of genu varum and genu valgum in primary school children in Iran 2003-2004. (2005) Journal of Medical Science 5(1). 52-54</a></li>
</ol>

Cytokine - A broad and loose category of small proteins that act through receptors, and are especially important to immune function (inflammation).
<ul>
 	<li>Cytokines include substances such as interferon, interleukin, and growth factors, which are secreted by certain cells of the immune system and have an effect on other cells. Their definite distinction from hormones is a topic of continued research.</li>
</ul>
&nbsp;

Dependent variable - in research, this is the variable that is changed by the independent variable, most often this is the "outcome" of the study.
<ul>
 	<li>Example, in the study by Cleland et al. (1), the independent variable is "thoracic manipulation," and the dependent variable is "lower trapezius muscle strength."</li>
</ul>
<ol>
 	<li><a href="https://brentbrookbush.com/articles/research-corner/short-term-effects-lower-thoracic-manipulation-lower-trapezius-muscle-strength/" target="_blank" rel="noopener noreferrer">Cleland J, Selleck B, Stowell T, Brown L, Alberini S, St. Cyr H, Caron T. Short-term Effects of Thoracic Manipulation on Lower Trapezius Muscle Strength.  Journal of Manual &amp; Manipulative Therapy. 2004; 12(2): 82-90</a></li>
</ol>

An anatomical direction; further from the trunk or center of the body

Example, the foot is at the distal end of the leg.

An arthrokinematic motion - a force applied to a body part that may result in the separation of joint surfaces, a reduction in intra-articular pressure, and/or an increase in intra-articlar space.

For example, to hang from one's hands (i.g. in preparation for a pull-up) results in a traction force on the glenohumeral joint (shoulder).

An anatomical term of location; back or upper surface

Example, shoe laces may compress tissues on the dorsal surface of the foot

The "drawing-in" maneuver is a common cue used during exercise and rehabilitation programs. A light contraction of the <a href="https://brentbrookbush.com/articles/muscular-anatomy/transverse-abdominis/" target="_blank" rel="noopener">transverse abominis</a> (and potentially the entire <a href="https://brentbrookbush.com/articles/corrective-exercise-articles/core-subsystems/intrinsic-stabilization-subsystem/" target="_blank" rel="noopener">intrinsic stabilization subsystem</a>) achieved by gently pulling the lower abdominal region away from one's waist band. This should have minimal effect on breathing, and should not be confused with a maximal contraction of the <a href="https://brentbrookbush.com/articles/muscular-anatomy/transverse-abdominis/" target="_blank" rel="noopener">transverse abdominis</a> resulting in a "vacuum pose".
<ul>
 	<li>Research often refers to this maneuver as the "abdominal drawing-in maneuver"; abbreviated ADIM.</li>
</ul>
Development and introduction of this cue into practice is based on the pivotal research and resulting text:
<ol>
 	<li>Carolyn Richardson, Paul Hodges, Julie Hides. Therapeutic Exercise for Lumbo Pelvic Stabilization – A Motor Control Approach for the Treatment and Prevention of Low Back Pain: 2nd Edition (c) Elsevier Limited, 2004</li>
</ol>

Faulty or abnormal movement; an alteration of normal kinematics.

For example, joint stiffness or a reduction in arthrokinematics motion that results in limited osteokinematic range of motion - inadequate inferior glide of the femoral head resulting in limited abduction of the hip.

The seeping into, or abnormal collection of fluid in a body cavity.

For example, knee effusion describes swelling within the knee joint.

Note: the word "effusion" is used differently in medicine than it is used in reference to the movement (seeping out) of liquids and gases, for example in chemistry.

&nbsp;

A trait of body tissues that allows a tissue to return to its resting length or state after deformation or stretch.
Example:  Muscle is elastic tissue; many muscles will return to their resting length after being stretched to 150% of that length without any appreciable change in tissue quality.

Elasticity: Elasticity refers to the ability of a cell to return to its resting length after being stretched/lengthened.
<ul>
 	<li>Note: this term is often confused with extensibility. Elasticity is not the ability to stretch; it is the ability to return to normal length after being stretched. Muscle tissue, connective tissue and even nerve tissue have varying levels of elasticity.</li>
</ul>
<ol>
 	<li>Saladin, K. (2012). Anatomy &amp; Physiology: The unity of form and function. (6th ed.). New York: McGraw-Hill.</li>
</ol>

Epithelial cell - One of the four basic cell types, found lining the body's cavities, blood vessels, organs and constitutes most gland tissue.  These cells are specialized to aid with absorption, secretion, or act as a barrier from foreign objects.
<ol>
 	<li>Saladin, K. S., &amp; Miller, L. (1998). Anatomy &amp; physiology. New York (NY): WCB/McGraw-Hill.</li>
</ol>

Equilibrium - a state in which opposing forces or influences are balanced.
<ul>
 	<li>For example, to maintain a neutral trunk while pushing or pulling a weight in one hand, your core musculature must balance the force by creating an equal amount of force in the opposite direction.</li>
</ul>

The study of causation, or origination. The word is commonly used in the medical professions, where it may refer to the study of why things occur, or the reason behind why things act a certain way.

For example, the etiology of low back pain is a complex subject, with multiple contributing factors and various structures implicated.

<div class="gs_citr" tabindex="0">Evidence-based medicine (practice) is the integration of best research evidence with clinical expertise and patient(client) values (2)."</div>
<ul>
 	<li class="gs_citr" tabindex="0">...the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients (clients).  It involves the integration of at least (a) clinical expertise/expert opinion, (b) external scientific evidence, and (c) client/patient/caregiver perspectives to provide high-quality services reflecting the interests, values, needs, and choices of the individuals we serve (1).</li>
</ul>
&nbsp;
<ol>
 	<li id="gs_cit1" class="gs_citr" tabindex="0">Sackett, D. L., Rosenberg, W. M., Gray, J. M., Haynes, R. B., &amp; Richardson, W. S. (1996). Evidence based medicine: what it is and what it isn't. Bmj, 312(7023), 71-72.</li>
 	<li class="gs_citr" tabindex="0">Sackett D et al. Evidence-Based Medicine: How to Practice and Teach EBM, 2nd edition. Churchill Livingstone, Edinburgh, 2000, p.1</li>
</ol>

Excitability: The ability of a cell to change in membrane conductance as a response to stimulation.

<ul>
 	<li>For example, muscle cells are specialized to react to a change in membrane potential with contraction, where as nerve cells are specialized to propagate a change in membrane potential along there axons and communicate that message to other tissues via neurotransmitters.
</li>
</ul>
<ol>
 	<li>Saladin, K. (2012). Anatomy &amp; Physiology: The unity of form and function. (6th ed.). New York: McGraw-Hill.</li>
</ol>

Excitation threshold: The level that a depolarization must reach for an action potential to occur.
<ul>
 	<li>The excitation threshold is a contributing factor to the "all-or-none" response of muscle and nerves cells to a stimulus.</li>
</ul>

Exercise Progression - Modification of an exercise with the intent of promoting adaptation by increasing demand. This can be accomplished by increasing reps, load, tempo, range of motion, complexity, and/or challenge to an individual's stability.
<ul>
 	<li>Because load, reps, tempo and complexity are often explicitly noted, the term "exercise progression" is most often used throughout Brookbush Institute (BI) content to refer to an exercise, or series of exercises that make it harder to maintain stability with good form.
<ul>
 	<li>Sample Exercise Progression: <a href="https://brentbrookbush.com/vimeo_videos/kneeling-chop-pattern/" target="_blank" rel="noopener">Kneeling Chop</a> to <a href="https://brentbrookbush.com/vimeo_videos/static-standing-chop-pattern/" target="_blank" rel="noopener">Standing Chop</a> to <a href="https://brentbrookbush.com/vimeo_videos/single-leg-chop-pattern/" target="_blank" rel="noopener">Single-leg Chop</a></li>
</ul>
</li>
</ul>

Exercise regression - The opposite of progression; that is, modification of an exercise with the intent of reducing demand. This can be accomplished by decreasing reps, load, tempo, range of motion, complexity, and/or challenge to an individual's stability. Generally, regressions are used to modify an exercise to the client's current level of ability, with the intent of improving form, motor learning and retention.
<ul>
 	<li>Because load, reps, tempo and complexity are often explicitly noted, the term "exercise regression" is most often used throughout Brookbush Institute (BI) content to refer to an exercise or series of exercises that make it easier to maintain stability with good form.
<ul>
 	<li>Sample Exercise Regression: <a href="https://brentbrookbush.com/vimeo_videos/single-leg-chop-pattern/" target="_blank" rel="noopener">Single-leg Chop</a> to <a href="https://brentbrookbush.com/vimeo_videos/static-standing-chop-pattern/" target="_blank" rel="noopener">Standing Chop</a> to <a href="https://brentbrookbush.com/vimeo_videos/kneeling-chop-pattern/" target="_blank" rel="noopener">Kneeling Chop</a></li>
</ul>
</li>
</ul>

Experimental Research - Studies in which the researchers introduce the variable to be studied, with the intent of observing the outcome. This is different than observational research which observes the effect of a variable already present. Many texts also assert that experimental research should include randomization and ideally a control group, as is seen in Randomized Control Trials. Studies in which the variable is introduced by the researchers, but participants are not randomized may be considered Quasi-experimental research.
<ul>
 	<li>In this study by Esformes, the experimental variable was squat depth and the outcome measures observed were various performance measures related to power (1).</li>
</ul>
<ol>
 	<li><a href="https://brookbushinstitute.com/article/back-squat-depth-lower-body-post-activation-potentiation/" target="_blank" rel="noopener">Esformes, J., &amp; Bampouras, T. (2013). Effect of back squat depth on lower-body postactivation potentiation. Journal of Strength and Conditioning Research, 27(11), 2997-3000.</a></li>
</ol>
&nbsp;

Extensibility: The ability of a cell to be stretched or lengthened without damage (1).
<ul>
 	<li>For example, most cells would rupture with even a modest stretch, but muscles can stretch up to 3 times their contracted length.</li>
</ul>
<ol>
 	<li>Saladin, K. (2012). Anatomy &amp; Physiology: The unity of form and function. (6th ed.). New York: McGraw-Hill.</li>
</ol>

False Negative - the proportion of negatives in a group that were assessed incorrectly (assessed as negative when the patient was actually positive)
<ul>
 	<li>Test Results: Although most tests/assessments result in either a positive or negative, the accuracy of a test is dependent on the number  of positives and negatives that are correct. Therefore, when the accuracy of a test is determined, their are 4 possible results, because a positive or negative result could be right (true) or wrong (false).</li>
</ul>

False Positive - the proportion of positives in a group that were assessed incorrectly (assessed as positive when the patient was actually negative)
<ul>
 	<li>Test Results: Although most tests/assessments result in either a positive or negative, the accuracy of a test is dependent on the number  of positives and negatives that are correct. Therefore, when the accuracy of a test is determined, their are 4 possible results, because a positive or negative result could be right (true) or wrong (false).</li>
</ul>

The function of fascia is to transmit force, provide support, and protect tissues. Fascia can effect motion by:
Transmitting force from one or more muscles (example: the thoracolumbar fascia)
Restricting motion in cases of adaptive shortening and/or adhesion to proximal structures (example: iliotibial band in cases of lower-leg dysfunction)
Elastic recoil after stretching can contribute to force production (example: plyometric exercise)

Note: There is evidence that fascia may house more receptors related to human movement than other tissues. In this way fascia may act as a motherboard for the nervous system

The fascial system does not contract or develop trigger points, and its capacity to adapt to stretching and or strengthening exercise is limited, especially when compared to the adaptive capacity of muscle tissue.

Fibromyalgia - A loosely defined diagnosis that is associated with a combination of widespread pain in combination with 2) tenderness at 11 or more of the 18 specific tender point sites. Consideration may also be given to the presence of psychosocial stressors and inflammatory disease in the patients history. Newer research suggests that fibromyalgia may be at least in part due to central sensitization of myofascial pain, often associated with trigger points (1 - 4).
<ol>
 	<li>Wolfe, F. (2018). Fibromyalgia Syndrome and Fibromyalgia Syndrome Criteria: Problems in Definition and Validity. Fibromyalgia Syndrome and Widespread Pain: From Construction to Relevant Recognition.</li>
 	<li>Wolfe, F., Smythe, H. A., Yunus, M. B., Bennett, R. M., Bombardier, C., Goldenberg, D. L., ... &amp; Fam, A. G. (1990). The American College of Rheumatology 1990 criteria for the classification of fibromyalgia. Arthritis &amp; Rheumatism: Official Journal of the American College of Rheumatology, 33(2), 160-172.</li>
 	<li>Alonso-Blanco, C., Fernandez-de-las-Penas, C., Morales-Cabezas, M., Zarco-Moreno, P., Ge, H. Y., &amp; Florez-García, M. (2011). Multiple active myofascial trigger points reproduce the overall spontaneous pain pattern in women with fibromyalgia and are related to widespread mechanical hypersensitivity. The Clinical journal of pain, 27(5), 405-413.</li>
 	<li>Staud, R., Nagel, S., Robinson, M. E., &amp; Price, D. D. (2009). Enhanced central pain processing of fibromyalgia patients is maintained by muscle afferent input: a randomized, double-blind, placebo-controlled study. PAIN®, 145(1-2), 96-104.</li>
</ol>
&nbsp;

Muscles that act to reduce or prevent movement at proximal joints to improve force transmission.
Example: The muscles of the core are important fixators; reducing motion of the spine/trunk to enhance force transmission between the extremities and environment.

An increase in joint stability via compressive forces resulting from muscular contraction and increased tension in fascial structures (1,2).
<ul>
 	<li>This term is most often used in reference to core intrinsic stabilizers, the thoracolumbar fascia and the sacroiliac joint; however, force closure and form closure have been mentioned in the literature referring to other joints.</li>
 	<li>Related term: Form closure</li>
</ul>
<ol>
 	<li>Andry Vleeming, Vert Mooney, Rob Stoeckart. Movement, Stability &amp; Lumbopelvic Pain: <a class="glossaryLink " title="Glossary: Integration" href="https://brentbrookbush.com/glossary/integration/" target="_blank" rel="noopener noreferrer" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Integration&lt;/div&gt;&lt;div class=glossaryItemBody&gt;Making a whole of parts.&lt;br /&gt;&lt;br /&gt;Example, The Brookbush Institute uses an integrative approach to explaining and addressing human movement.&lt;/div&gt;">Integration</a> of Research and Therapy. (c) 2007 Elsevier Limited</li>
 	<li id="gs_cit1" class="gs_citr" tabindex="0">Vleeming, A., Pool-Goudzwaard, A. L., Stoeckart, R., van Wingerden, J. P., &amp; Snijders, C. J. (1995). The Posterior Layer of the Thoracolumbar Fascia| Its Function in Load Transfer From Spine to Legs. Spine, 20(7), 753-758.</li>
</ol>

The relative contribution of joint shape and structure to the stability of a joint (1,2).
<ul>
 	<li>This term is most often used in reference to the "rough" articulating surfaces of the sacroiliac joint and the wedge shape of the sacrum; however, force closure and form closure have been mentioned in the literature referring to other joints.</li>
 	<li>Related term: Force closure</li>
</ul>
<ol>
 	<li>Andry Vleeming, Vert Mooney, Rob Stoeckart. Movement, Stability &amp; Lumbopelvic Pain: <a class="glossaryLink " title="Glossary: Integration" href="https://brentbrookbush.com/glossary/integration/" target="_blank" rel="noopener noreferrer" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Integration&lt;/div&gt;&lt;div class=glossaryItemBody&gt;Making a whole of parts.&lt;br /&gt;&lt;br /&gt;Example, The Brookbush Institute uses an integrative approach to explaining and addressing human movement.&lt;/div&gt;">Integration</a> of Research and Therapy. (c) 2007 Elsevier Limited</li>
 	<li id="gs_cit1" class="gs_citr" tabindex="0">Vleeming, A., Pool-Goudzwaard, A. L., Stoeckart, R., van Wingerden, J. P., &amp; Snijders, C. J. (1995). The Posterior Layer of the Thoracolumbar Fascia| Its Function in Load Transfer From Spine to Legs. Spine, 20(7), 753-758.</li>
</ol>

An arthrokinematic motion - linear motion across a joint surface parallel to the plane of the adjacent joint surface, just as your posterior moves relative to a "slide" in a park.

For example, the glide of facet joint in the spine during spinal flexion and extension, or the posterior glide of the humeral head that must accompany anterior roll to maintain congruence with glenoid fossa during shoulder horizontal adduction.

A plane joint (also called an arthrodial joint, gliding joint or plane articulation) is a synovial joint which allows only gliding movement in the plane of the articular surfaces. The opposed surfaces of the bones are flat or almost flat, with movement generally limited by tight capsules and ligaments. Plane joints are numerous, are most often small, and allow very little motion.  Examples include the carpal joints of the wrist, the tarsal joints of the ankle, and the facet joints of the spine.

"...refers to the measurement of angles, in particular the measurement of angles created at human joints by the bones of the body (1).

&nbsp;
<ol>
 	<li>Cynthia C. Norkin, D. Joyce White. Measurement of Joint Motion: A Guide to Goniometry 3rd Edition. Copyright (C) 2003 by F.A. Davis Company</li>
</ol>

Ground reaction force (GRF) - The force exerted by the ground on the body in contact with it.

For example, when a runner's foot strikes the ground with a force equal to the mass of the individual times their acceleration due to gravity, momentum and muscular exertion, the ground exerts an equal and opposite force on the runner's foot.
<ul>
 	<li>GRF is often measured in research studies using force plates as a means of quantitatively measuring the force generated by an individual.</li>
</ul>

H-Band - Refers to the central zone of a sarcomere that looks lighter under a microscope.  This area of the sarcomere is a lighter portion of the A-band where there is no overlap between the thinner filaments (actin), and the thicker filaments (myosin).
<ul>
 	<li>Example, when a muscle contracts, actin and myosin cross-bridging occurs in the region of the A-band until the H-band is reached where no overlap occurs.</li>
</ul>
<ol>
 	<li>Saladin, K. (2014). Anatomy &amp; physiology: The unity of form and function. McGraw-Hill Higher Education, New York. ISBN: 9780073403717</li>
</ol>

A hinge joint (also called a ginglymus) is a synovial joint in which the articular surfaces fit one another in a way that only permits motion in one plane. Examples include the elbow, the knee (unless considered a condyloid joint) and the interphalangeal joints.

Holism (holistic) (biological holism) - (from Greek holos "all, whole, entire") is the idea that systems and their properties should be viewed as wholes, not just as a collection of parts.
<ul>
 	<li>Summarized by Aristotle in his "Metaphysics": "The whole is more than the sum of its parts". However, the term "holism" was introduced into language by the South African statesman Jan Smuts as recently as 1926. (Smuts J. C. 1987 [1926]. Holism and evolution. Cape Town: N &amp; S Press.)</li>
</ul>
Example: The Brookbush Institute promotes a holistic approach to human movement science, in which the muscular, fascial, articular and neural systems are not viewed as separable and all proximal segments are considered.

Hormone: Chemical messengers produced by the endocrine system, transported via tissue fluids such as blood, to stimulate cells to "act."
<ul>
 	<li>Example: Growth hormone is secreted by the pituitary gland in the brain; stimulating growth, cell reproduction and cell regeneration in certain types of cells</li>
</ul>
The English physician E. H. Starling discovered in collaboration with the physiologist W. M. Bayliss secretin, the first hormone, in 1902. (1).
<ol>
 	<li>Henriksen, J. H., &amp; de Muckadell, O. S. (2000). Secretin, its discovery, and the introduction of the hormone concept. Scandinavian journal of clinical and laboratory investigation, 60(6), 463-472.</li>
</ol>

A range of motion achieved by the patient/client that is more than normal.
<ul>
 	<li>Note: Both hyper-mobility and hypo-mobility may adversely affect motion and may lead to deleterious effects on joints and soft tissue over time. There is no evidence to suggest that more or less flexibility than normal is beneficial.</li>
</ul>
Example: If an individual can place their forehead on their knees they are likely hypermobile at one, if not several joints

Example 2: 110° of shoulder external rotation would be considered hyper-mobile.

Hyperplasia is an increase in organic tissue size due to an adaptive increase in the number of cells per organ.
<ul>
 	<li>Although muscle hyperplasia has been noted in some animals, human muscle tissue does not seem to have this adaptive ability.</li>
</ul>

A condition of excessive tone of the skeletal muscles; increased resistance of muscle to passive stretching.  May be related to increased neural drive, synergistic dominance, trigger points, reflexive over-activity, and/or muscle length.
Example:  Individuals who exhibit ankle eversion and abduction during an overhead squat assessment likely have hypertonic fibularis (peroneal) muscles.

Muscular hypertrophy is an increase in muscle mass/size due to increase in the volume and cross-sectional area (CSA) of individual muscle cells. The increase in cross-sectional area can be attributed to an an increase in contractile proteins and structural elements (myofibrillar hypertophy), as well as an increase in glycogen storage and elements related to metabolism (sarcoplasmic hypertophy). Hypertrophy is an adaptation of both cardiac and skeletal muscle fibers in response to progressive increases in workload.
<ul>
 	<li>Note: Hypertrophy is not hyperplasia. Hyperplasia is an increase in muscle size due to an adaptive increase in the number of muscle fibers/cells per muscle. This type of adaptation does not occur in human muscle tissue.</li>
</ul>

A range of motion achieved by a patient/client that is less than normal.
<ul>
 	<li>Note: Both hyper-mobility and hypo-mobility may adversely affect motion and may lead to deleterious effects on joints and soft tissue over time. There is no evidence to suggest that more or less flexibility than normal is beneficial.</li>
</ul>
Example: If the end range of shoulder external rotation is reached and measured as 75° during goniometric assessment, the client/patient is exhibiting hypomobility of the glenohumeral joint (shoulder).

Hypothesis - a proposed explanation for a phenomenon; "scientific hypotheses" are generally constructed in a way that is testable or falsifiable.
<ul>
 	<li>Example: The hypothesis, "excessive knee valgus may be correlated with future knee pain and injury," has been the subject of several studies published over the last decade.</li>
</ul>

Diminished tone of skeletal muscles; diminished resistance of muscles to passive stretching.   May be related to inhibition, reciprocal inhibition, arthrokinematics inhibition and/or  increased resting length of muscle.
Example:  If your knees cave (hip adduction) during a squat or leg-press it is likely that your gluteus medius is hypotonic.

I-Band - Refers to the part of the muscle cell that looks lighter under a microscope.  This area of the cell is lighter due to parallel arrangement of thinner filaments (actin), and no overlap with the thicker filaments (myosin).
<ul>
 	<li>As a muscle contracts, the I-bands will decrease in width and move closer to one another.</li>
</ul>
<ol>
 	<li>Saladin, K. (2014). Anatomy &amp; physiology: The unity of form and function. McGraw-Hill Higher Education, New York. ISBN: 9780073403717</li>
</ol>

Independent variable - in research, this is the variable or phenomenon being manipulated in the study.
<ul>
 	<li>Example, in the study by Ghanbari et al. (1), the independent variable is "knee joint mobilization", the dependent variable is "quadriceps muscle strength."</li>
</ul>
<ol>
 	<li><a href="https://brentbrookbush.com/articles/research-corner/effect-knee-joint-mobilization-quadriceps-muscle-strength/" target="_blank" rel="noopener noreferrer">Ghanbari A. and Kamalgharibi S. (2013). Effect of knee joint mobilization on quadriceps muscle strength. International Journal of Health and Rehabilitation Sciences. 2(4): 186-191</a></li>
</ol>

An anatomical direction; toward the bottom (below)

Example, the mouth is inferior to the eyes

A reduction in neural drive, muscular activity, and or force output due to altered neuromuscular reflex.  Alterations in neuromuscular reflex may occur due to increases in muscle length (hypothesis: increased excitation threshold), altered reciprocal inhibition in response to increased antagonist tone, and or alterations in joint motion (arthrokinematics inhibition).

Making a whole of parts.

Example, The Brookbush Institute uses an integrative approach to explaining and addressing human movement.

Intermuscular Coordination - Optimal timing and motor unit recruitment of agonists, antagonists, synergists, neutralizers, stabilizers and fixators.

Example: Role of Muscles during Hip Extension
<ul>
 	<li><a class="glossaryLink " style="box-sizing: border-box; font-family: roboto; color: #000000 !important; font-size: 15px; outline: none; background: transparent; border-bottom: 1px dotted #000000 !important; text-decoration: none;" title="Glossary: Prime Mover" href="https://brentbrookbush.com/glossary/prime-mover/" target="_blank" rel="noopener" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Prime Mover&lt;/div&gt;The muscle most responsible for a joint action under load -&lt;br /&gt;&lt;br /&gt;That is, the muscle that can produce the most force for a given joint action. Often this term is used synonymously with the term agonist. The prime mover as defined above, may or may not be the most active muscle for a joint action during activities of daily living.&lt;br /&gt;&lt;br /&gt;Example: the gluteus maximus is the most powerful hip extensor and therefore the prime mover; however, the hamstrings are likely the most active hip extensors during low level activities like walking or standing.">Prime Mover</a>:  <a href="https://player.vimeo.com/external/82855344.hd.mp4?s=54c3e7d98fb9d4e0af8d282c85ba9b3e">Gluteus maximus</a></li>
 	<li><a class="glossaryLink " style="box-sizing: border-box; font-family: roboto; color: #000000 !important; font-size: 15px; outline: none; background: transparent; border-bottom: 1px dotted #000000 !important; text-decoration: none;" title="Glossary: Synergists" href="https://brentbrookbush.com/glossary/synergists/" target="_blank" rel="noopener" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Synergists&lt;/div&gt;Muscles that assist the prime mover in performing a joint action.&lt;br /&gt;&lt;br /&gt;That is, all muscles that can perform a joint action that are not the prime mover, are termed synergists.&lt;br /&gt;Example: The rectus abdominis is the prime mover of spinal flexion. All other muscles that can perform spinal flexion are synergists including – external obliques, internal obliques and psoas.">Synergists</a>: <a href="https://brentbrookbush.com/articles/muscular-anatomy/biceps-femoris/">Biceps femoris (long head)</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/semitendinosus-and-semimembranosus/">semitendinosus, semimembranosus</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/adductors/">posterior head of adductor magnus</a></li>
 	<li><a class="glossaryLink " style="box-sizing: border-box; font-family: roboto; color: #000000 !important; font-size: 15px; outline: none; background: transparent; border-bottom: 1px dotted #000000 !important; text-decoration: none;" title="Glossary: Antagonist" href="https://brentbrookbush.com/glossary/antagonists/" target="_blank" rel="noopener" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Antagonist&lt;/div&gt;Muscles that oppose the prime mover and synergists for a given joint action.&lt;br /&gt;&lt;br /&gt;That is, all the muscles that can perform the opposing joint action.&lt;br /&gt;&lt;br /&gt;Example: The triceps and anconeus are antagonists during elbow flexion.">Antagonists</a>: <a href="https://brentbrookbush.com/articles/muscular-anatomy/psoas/">Psoas</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/iliacus/">iliacus</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/tensor-fascia-latae-tfl/">tensor fascia latae</a> (TFL),<a href="https://brentbrookbush.com/articles/muscular-anatomy/rectus-femoris/"> rectus femoris</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/adductors/">anterior adductors (especially pectineus)</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/sartorius/">sartorius</a></li>
 	<li><a class="glossaryLink " style="box-sizing: border-box; font-family: roboto; color: #000000 !important; font-size: 15px; outline: none; background: transparent; border-bottom: 1px dotted #000000 !important; text-decoration: none;" title="Glossary: Neutralizer" href="https://brentbrookbush.com/glossary/neutralizers/" target="_blank" rel="noopener" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Neutralizer&lt;/div&gt;Muscles that oppose unwanted joint motions created by the prime mover and/or synergists, and/or muscles that prevent unwanted ancillary motion.&lt;br /&gt;Example: The teres minor and infraspinatus neutralize the internal rotation force created by the pectoralis major during horizontal adduction of the shoulder.">Neutralizers</a>: <a href="https://brentbrookbush.com/articles/muscular-anatomy/gluteus-minimus/">Gluteus minimus</a> and <a href="https://brentbrookbush.com/articles/muscular-anatomy/gluteus-medius/">anterior fibers of gluteus medius</a> neutralize external rotation force of <a href="https://brentbrookbush.com/articles/muscular-anatomy/gluteus-maximus/">gluteus maximus</a></li>
 	<li><a class="glossaryLink " style="box-sizing: border-box; font-family: roboto; color: #000000 !important; font-size: 15px; outline: none; background: transparent; border-bottom: 1px dotted #000000 !important; text-decoration: none;" title="Glossary: Stabilizer" href="https://brentbrookbush.com/glossary/stabilizers/" target="_blank" rel="noopener" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Stabilizer&lt;/div&gt;Muscles whose primary role is to improve arthrokinematics by maintaining optimal alignment of joint surfaces.&lt;br /&gt;&lt;br /&gt;Most often these muscles are the most intrinsic muscles of a joint, have a larger percentage of Type I muscle fibers and are rich in proprioceptors.&lt;br /&gt;Example: The muscles of the rotator cuff act as stabilizers for most shoulder motions.">Stabilizers</a>: <a href="https://brentbrookbush.com/articles/muscular-anatomy/deep-rotators-of-the-hip/">Deep rotators of hip</a></li>
 	<li><a class="glossaryLink " style="box-sizing: border-box; font-family: roboto; color: #000000 !important; font-size: 15px; outline: none; background: transparent; border-bottom: 1px dotted #000000 !important; text-decoration: none;" title="Glossary: Fixator" href="https://brentbrookbush.com/glossary/fixators/" target="_blank" rel="noopener" data-cmtooltip="&lt;div class=glossaryItemTitle&gt;Fixator&lt;/div&gt;Muscles that act to reduce or prevent movement at proximal joints to improve force transmission.&lt;br /&gt;Example: The muscles of the core are important fixators; reducing motion of the spine/trunk to enhance force transmission between the extremities and environment.">Fixators</a>: <a href="https://brentbrookbush.com/articles/core-subsystems/intrinsic-stabilization-subsystem/">Intrinsic stabilization subsystem</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/rectus-abdominis/">rectus abdominis</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/internal-obliques/">internal</a> and <a href="https://brentbrookbush.com/articles/muscular-anatomy/external-obliques/">external obliques</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/quadratus-lumborum/">quadratus lumborum</a>, <a href="https://brentbrookbush.com/articles/muscular-anatomy/erector-spinae/">erector spinae</a></li>
</ul>
&nbsp;

Example from: <a href="https://brentbrookbush.com/articles/anatomy-articles/introduction-to-functional-anatomy/kinesiology-of-the-hip/" target="_blank" rel="noopener">Introduction to Functional Anatomy: Kinesiology of the Hip</a>

Intramuscular coordination refers to the coordinated recruitment of motor units within a single muscle. This concept is used to explain increases in maximal strength and power; however, the coordinated and sequential recruitment of motor units is also essential to strength endurance and smooth coordinated motion.  Related terminology may include; motor unit recruitment, preferential recruitment, rate coding, sequence, etc..

Example: It is hypothesized that the "shaking" noted during a novice exercisers attempt at an activity like the <a href="https://brentbrookbush.com/vimeo_videos/ball-crunch-and-progressions/" target="_blank">stability ball crunch</a> may be due to relatively poor intramuscular coordination. Rather than smooth, sequential firing of rectus abdominis motor units, groups of motor units turn on and off in an uncoordinated manner.

Pertaining to the same side

Example, the quadratus lumborum performs ipsilateral flexion; lateral flexion toward the same side as the muscle.

An isoform, or variant, is a member of a set of similar proteins, that originate from the same gene, or gene family.
<ul>
 	<li>Example, the variations in myosin heavy chain proteins (MHC I, MHC IIA, MHC IIB/X) that contribute to the characteristic differences between muscle fiber types.</li>
</ul>

“The Prime Assumption”
Everything crossing a joint will influence joint motion during every joint action.

A concept that has expanded over the past several decades to describe the integration of 4 body systems (muscle, joints, fascia and nerves), as well as, the coordinated function of various body segments (e.g. hip, knee and ankle) to produce motion. Kinetic referring to motion, and chain being an analogy for the interdependent link between systems.

Example, the posterior kinetic chain, refers to the integrated function of nerves, muscles, fascia and joints on the posterior side of the body.

The concept of the kinetic chain was originally adapted from the work of a mechanical engineer named Franz Reuleaux (Kinematics of Machinery (1875)) by Dr. Arthur Steindler in 1955 (Steindler A: Kinesiology of the Human Body. Springfield, IL, Charles C. Thomas Co.. 1955).

Latent Trigger Point - A myofascial trigger point that is not painful at rest, only painful when palpated, and may or may not exhibit a characteristic referral pain pattern when palpated.  Latent trigger points do result in an acute point of sensitivity, in a taut band of muscle, and may restrict range of motion (1).

Note: Based on the clinical experience, the Brookbush Institute suggests that latent trigger points (sometimes refereed to as Tender Points) are more common than active trigger points. Further, they are likely addressed more often than trigger points; being the intended target of many soft-tissue mobility techniques.
<ol>
 	<li>David G. Simons, Janet Travell, Lois S. Simons, Travell &amp; Simmons’ Myofascial Pain and Dysfunction, The Trigger Point Manual, Volume 1. Upper Half of Body: Second Edition,© 1999 Williams and Wilkens</li>
</ol>

An anatomical direction; further from the midline

Example, the anterior deltoid is lateral to the pectoralis major

Length/Tension Relationship - The amount of force generated by a muscle is dependent on sarcomere length.
<ul>
 	<li>The ability of sarcomere to maximally produce force occurs when sarcomere length results in optimal overlap between actin and myosin. Stretching a sarcomere decreases overlap between actin and myosin filaments and reduces force production (1-3). When length is less than optimal, actin from opposite ends overlap and interfere with cross-bridging, and myosin filament are compressed as they contact the the Z-disk also reducing force (4)</li>
</ul>
<ol>
 	<li>Gordon, A. M., Huxley, A. F., &amp; Julian, F. J. (1966). The variation in isometric tension with sarcomere length in vertebrate muscle fibres. The Journal of physiology, 184(1), 170-192.</li>
 	<li>Edman, K. A. P. (1966). The relation between sarcomere length and active tension in isolated semitendinosus fibres of the frog. The Journal of Physiology, 183(2), 407-417.</li>
 	<li>Lieber, R. L., Loren, G. J., &amp; Friden, J. (1994). In vivo measurement of human wrist extensor muscle sarcomere length changes. Journal of neurophysiology, 71(3), 874-881.</li>
 	<li>Lieber, R. L. (2002). Skeletal muscle structure, function, and plasticity. Lippincott Williams &amp; Wilkins.</li>
</ol>
&nbsp;

Levels of Evidence - Relative to evidence-based practice, levels of evidence are an attempt to describe the strength of the results measured in a clinical trial or research study.  Note: levels of evidence do not supersede the critical evaluation of an experienced professional, and should be viewed as guidelines - a meta-analysis may be poorly constructed (Level IA), and a comparative study (Level III) may employ new technologies and a strong methodology.


The Levels of Evidence used by the Brookbush Institute, as described by Shekelle et al.(1):
<ul>
 	<li class="p1">IA - Evidence from meta-analysis of randomized controlled trials</li>
 	<li class="p1">IB - Evidence from at least one randomized controlled trial</li>
 	<li class="p1">IIA - Evidence from at least one controlled study without randomization</li>
 	<li class="p1">IIB - Evidence from at least one other type of quasi-experimental study</li>
 	<li class="p1">III - Evidence from non-experimental descriptive studies, such as comparative studies, correlation studies, and case-control studies</li>
 	<li class="p1">IV - Evidence from expert committee reports or opinions or clinical experience of respected authorities, or both</li>
</ul>
<ol>
 	<li>Shekelle, P. G., Woolf, S. H., Eccles, M., &amp; Grimshaw, J. (1999). Developing clinical guidelines. Western Journal of Medicine, 170(6), 348.</li>
</ol>

Likelihood Ratios - Likilihood ratios are used for assessing the value of performing a diagnostic test. They use sensitivity and specificity to determine whether a test result usefully changes the practitioner's chance (probability) of reaching the correct assessment. Calculation of likelihood ratios is based on Baye's theorem.
<ul>
 	<li>Positive Likelihood Ratio (LR+) - The ratio of a positive test result in people with the pathology to a positive test result in people without the pathology.</li>
 	<li>Negative Likelihood Ratio (LR-) - The ratio of a negative test result in people with the pathology to a negative test result in people without the pathology.</li>
</ul>

Longitudinal Study - a research design that involves observing the same variables, several times over a period of time.
<ul>
 	<li>Example, the study by Hewett et al. (1) is a type of longitudinal study called a "cohort study." This study investigated whether excessive knee valgus during landing was a predictor of knee injury risk in adolescent females over the course of a season.</li>
</ul>
<ol>
 	<li><a href="https://brentbrookbush.com/articles/research-corner/knee/research-review-increased-valgus-during-landing-predicts-acl-injury-in-adolescent-female-athletes/" target="_blank" rel="noopener noreferrer">Hewett, T. E., Myer, G. D., Ford, K. R., Heidt, R. S., Colosimo, A. J., McLean, S. G., &amp; Succop, P. (2005). Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes A prospective study. The American journal of sports medicine, 33(4), 492-501</a></li>
</ol>

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