Introduction

Kinesiology

Squats

Comparing the Squat, Lunge and Bulgarian Split-Squat

Comparing the Squat, Step-up and Single-leg Squat

Comparing the Unilateral Lower Body Exercise for Stable and Unstable Surfaces

Research Summary

Leg Exercises and Lower Body Exercise Progressions

PACE

NYPT

WITS

TPTA

NASM

AOTA

REPSI

AUSPHYSIO

ISSA

CIMSPA

AUSactive

ACSM

AFAA

CanFitPro

REPS

PTAGlobal

Legs/Triple Extension Progressions

This course discusses variations, <a id="exercise-progression" data-tip="1182" target="_blank" href="/glossary-term/exercise-progression" class="glossary">progressions</a>, and <a id="exercise-regression" data-tip="1178" target="_blank" href="/glossary-term/exercise-regression" class="glossary">regressions</a> of leg exercises for increasing lower body strength. More sophisticated leg workouts and leg day routines can be created with multiple variations of squats, split squats, <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> lunges, single leg exercises, bodyweight leg exercises, etc. Note, <a href="https://brookbushinstitute.com/courses/bridge-progression">bridge progressions</a> for glutes, <a href="https://brookbushinstitute.com/courses/deadlift-progression">deadlifts</a> for hips, and <a href="https://brookbushinstitute.com/courses/power-training-lower-body-exercises" target="_blank" rel="noopener">reactive drills</a> for foot placement, are covered in separate courses. This course features more functional movement patterns for improving leg strength than the leg presses, hack squats, leg curls (seated leg curls and <a id="prone" data-tip="1561" target="_blank" href="/glossary-term/prone" class="glossary">prone</a> hamstring curls), leg extensions (knee extensions), and/or other machines found in a gym setting that claim to &quot;target&quot; the glutes, hips muscles, or calf muscles. Further, this course includes detailed cueing, including foot placement during a squat (e.g. hips or feet shoulder width), how to tell the correct distance between the right and left foot during a reverse lunge, what to do with the left leg when doing a right leg single leg deadlift touchdown, or the <a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a> starting position for the hips during a dumbbell front squat. This course will provide a variety of ideas and concepts to use on leg day, during the leg workout portion of your routine, or during leg day home workouts.&#xA0;
Additionally, this course covers the functional anatomy of leg exercises for lower body strength, including the contribution of the hip muscles (e.g. glutes a.k.a. gluteus maximus and gluteus medius), knee muscles (e.g. quadriceps), ankle muscles (e.g. gastrocnemius and soleus), and core muscles (e.g. erector spinae, obliques, hip flexors, etc.). More advanced anatomical considerations include the contribution of core subsystems (e.g. <a href="deep%20longitudinal%20subsystem" target="_blank" rel="noopener">deep longitudinal subsystem</a>), the use of lower body strength exercises during neuromuscular re-education (a.k.a. <a id="integration" data-tip="1472" target="_blank" href="/glossary-term/integration" class="glossary">integration</a> exercises), and the potential of over-active hip flexors or calf muscles to restrict motion and decrease performance. Further, this course is built from a systematic research review, it is pre-approved for credits toward the Certified Personal Trainer (CPT) Certification, and pre-approved for continuing education credits for movement professionals (personal trainers, fitness instructors, physical therapists, athletic trainers, massage therapists, chiropractors, occupational therapists, etc.).
We hope this course inspires the inclusion of leg exercises for all goals in fitness, performance, and physical rehabilitation. For example, workouts for increase glute and hamstring hypertrophy for physique athletes, routines to increase single-leg strength for powerlifters and field sport athletes, and the creation of home exercise programs for maintaining <a id="mobility" data-tip="1455" target="_blank" href="/glossary-term/mobility" class="glossary">mobility</a>, core strength, and reconditioning after lower extremity injury in a clinical setting.
<h3>Additional Progression Courses:</h3>
<h4>Strength Progressions</h4>
<ul>
 <li><a href="https://brookbushinstitute.com/courses/chestpushing-movements">Chest Exercise and Pushing Progressions</a></li>
 <li><a href="https://brookbushinstitute.com/courses/back-pulling-movement-patterns">Back Exercise and Pulling Progressions</a></li>
 <li><a href="https://brookbushinstitute.com/courses/shoulderoverhead-pressing-patterns">Shoulder Exercise and Pressing Progressions</a></li>
 <li><a href="https://brookbushinstitute.com/courses/lower-bodytriple-extension-movements">Leg Exercise and Triple Extension Progressions</a></li>
 <li><a href="https://brookbushinstitute.com/courses/deadlift-progression" target="_blank" rel="noopener">Deadlift Exercise Progressions</a></li>
 <li><a href="https://brookbushinstitute.com/courses/stability-progression-for-integrated-exercise">Total Body Exercise and </a><a id="integration" data-tip="1473" target="_blank" href="/glossary-term/integration" class="glossary">Integrated</a> Progressions</li>
</ul>
<h4>Core Progressions</h4>
<ul>
 <li><a href="https://brookbushinstitute.com/courses/transverse-abdominis-activation-quadrupeds-progressions">Quadruped and Progressions</a></li>
 <li><a href="https://brookbushinstitute.com/courses/plank-progression">Plank and Side Plank Progressions</a></li>
 <li><a href="https://brookbushinstitute.com/courses/bridge-progression">Glute Bridge and Progressions</a></li>
 <li><a href="https://brookbushinstitute.com/courses/chop-pattern-progressions">Wood Chop Exercise Progressions</a></li>
</ul>
<h4>Power Progressions</h4>
<ul>
 <li><a href="https://brookbushinstitute.com/courses/power-training-upper-and-total-body">Power Training: Upper Body and Total Body Exercise</a></li>
 <li><a href="https://brookbushinstitute.com/courses/power-training-lower-body-exercises">Power Training: Lower Body Exercise</a></li>
</ul>
<h2>Sample Progression: Lunge Progressions</h2>
Load Progressions:
<ol>
 <li>Holding a weight at the sides</li>
 <li>Front-loaded</li>
 <li><a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">Unstable</a> load (weights suspended from a barbell with bands, or using liquid-filled tubes)</li>
</ol>
Motion Progressions:
<ol>
 <li>Static lunge
 <ul>
 <li>Frontal plane</li>
 </ul>
 </li>
 <li>Static lunge <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a>
 <ul>
 <li>Frontal plane</li>
 </ul>
 </li>
 <li>Dynamic lunge
 <ul>
 <li>Reverse</li>
 <li>Forward</li>
 <li>Frontal plane</li>
 <li>Transverse plane</li>
 </ul>
 </li>
 <li>Dynamic lunge to single-leg <a id="balance" data-tip="1190" target="_blank" href="/glossary-term/balance" class="glossary">balance</a>
 <ul>
 <li>Reverse</li>
 <li>Forward</li>
 <li>Frontal plane</li>
 <li>Transverse plane</li>
 </ul>
 </li>
 <li>Dynamic lunge to single leg <a id="balance" data-tip="1190" target="_blank" href="/glossary-term/balance" class="glossary">balance</a> <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a>
 <ul>
 <li>Reverse</li>
 <li>Forward</li>
 <li>Frontal plane</li>
 <li>Transverse plane</li>
 </ul>
 </li>
</ol>
<ol></ol>
<ol></ol>
<h2>Sample Program</h2>
<h3>Routine 1 (Month 1)</h3>
Goal: Lower Body Hypertrophy (Strength/Stability Supersets)
Acute Variables: 
<ul>
 <li>Load: Moderate (75-90% 1-RM)/Light (60-75% 1-RM)</li>
 <li>Reps/set: 6-12/6-12</li>
 <li>Sets/exercise (or circuits): 1-5 circuits</li>
 <li>Rest between exercises: 60 seconds</li>
 <li>Rest between Circuits: 1-3&#xA0;minutes (alternatively, can be performed in a circuit)</li>
 <li>Training time: 20 &#x2013; 60 minutes (excluding warm-up).</li>
</ul>
Strength/Stability Super-sets Routine: 
<ul>
 <li>Total Body: <a href="https://brookbushinstitute.com/videos/anterior-oblique-subsystem-integration-step-up-to-chest-press" target="_blank" rel="noopener">Step up to </a><a id="balance" data-tip="1190" target="_blank" href="/glossary-term/balance" class="glossary">Balance</a> to Press</li>
 <li> Strength: <a href="https://brookbushinstitute.com/videos/deadlift-with-posterior-pull" target="_blank" rel="noopener">Deadlift with </a><a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">Posterior</a> Pull</li>
 <li>Stability: <a href="https://brookbushinstitute.com/videos/wobble-lunge" target="_blank" rel="noopener">Transverse Plane Wobble Lunge</a></li>
 <li>Active Rest (Corrective, <a id="mobility" data-tip="1455" target="_blank" href="/glossary-term/mobility" class="glossary">mobility</a> not appropriate): <a href="https://brookbushinstitute.com/videos/posterior-tibialis-activation-progression-4">Tibialis </a><a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">Posterior</a> Activation</li>
</ul>
<h3>Routine 2 (Month 2)</h3>
Acute Variables: 
<ul>
 <li>Goal: Lower Body Max Strength/Power (Post-activation <a id="post-activation-potentiation" data-tip="1393" target="_blank" href="/glossary-term/post-activation-potentiation" class="glossary">Potentiation</a> Circuits)</li>
 <li>Load: (Heavy &gt; 85% of 1-RM) (Light &lt; 30% of 1-RM</li>
 <li>Reps/set: (1-5)(3-10)</li>
 <li>Sets/exercise (circuits): 2-6 circuits</li>
 <li>Rest between exercises: 1-2 minutes&#xA0;(note, exercise performed in circuit)</li>
 <li>Training Time: 20 &#x2013; 45 minutes (excluding warm-up).</li>
</ul>
Post-activation <a id="post-activation-potentiation" data-tip="1393" target="_blank" href="/glossary-term/post-activation-potentiation" class="glossary">Potentiation</a> (<a id="post-activation-potentiation" data-tip="1392" target="_blank" href="/glossary-term/post-activation-potentiation" class="glossary">PAP</a>) Circuit Routine: 
<ul>
 <li>Total Body: <a href="https://brookbushinstitute.com/videos/power-row-sled-pull" target="_blank" rel="noopener">Power Row Sled Pull</a></li>
 <li>Max Strength: <a href="https://brookbushinstitute.com/videos/back-squat" target="_blank" rel="noopener">Back Squat</a></li>
 <li>Power: <a href="https://brookbushinstitute.com/videos/depth-jump" target="_blank" rel="noopener">Depth Jump</a></li>
 <li>Active Rest (corrective/mobility not appropriate): <a href="https://brookbushinstitute.com/videos/tibialis-anterior-isolated-activation" target="_blank" rel="noopener">Tibialis </a><a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">Anterior</a> Activation</li>
</ul>

Course Description: Leg Exercises and Lower Body Exercise Progressions

<h3>Quick Study Guide: <a href="https://www.datocms-assets.com/25800/1686624826-leg-exercises-and-lower-body-exercise-progressions-study-guide-v3-pdf.pdf">Leg Exercises and Lower Body Exercise Progressions</a></h3>
For a comprehensive review of <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> load and surface training:
<ul>
 <li><a href="https://brookbushinstitute.com/courses/stability-training" target="_blank" rel="noopener">Stability Training</a></li>
</ul>
<h3>Relative Flexibility Progression:</h3>
<a id="relative-flexibility" data-tip="1654" target="_blank" href="/glossary-term/relative-flexibility" class="glossary">Relative flexibility</a> <a id="exercise-progression" data-tip="1182" target="_blank" href="/glossary-term/exercise-progression" class="glossary">progressions</a> are general guidelines for exercise selection that can be used while correcting <a id="posture" data-tip="1659" target="_blank" href="/glossary-term/posture" class="glossary">postural</a> dysfunction/movement impairment. These <a id="exercise-progression" data-tip="1182" target="_blank" href="/glossary-term/exercise-progression" class="glossary">progressions</a> are in order from least to most demanding relative to <a id="mobility" data-tip="1455" target="_blank" href="/glossary-term/mobility" class="glossary">mobility</a> and neuromuscular control. Individuals exhibiting signs of <a href="https://brookbushinstitute.com/courses/lumbo-pelvic-hip-complex-dysfunction-lphcd" target="_blank" rel="noopener">lumbopelvic hip complex dysfunction (LPHCD)</a> or <a href="https://brookbushinstitute.com/courses/lower-leg-dysfunction" target="_blank" rel="noopener">lower extremity dysfunction (LED)</a> may reduce the chance of compensation by integrating lower body movement patterns in the following order:
<ol>
 <li>Ball Wall Squats</li>
 <li>Squats</li>
 <li>Step-Ups</li>
 <li>Lunges</li>
</ol>
<h3>Subsystems Recruited:</h3>
The majority of lower extremity exercises require significant trunk stabilization and coordinated recruitment of all core subsystems. The <a href="https://brookbushinstitute.com/courses/instrinsic-stabilization-subsystem" target="_blank" rel="noopener">intrinsic stabilization subsystem</a> maintains segmental stabilization and alignment, while balanced recruitment of the <a href="https://brookbushinstitute.com/courses/anterior-oblique-subsystem-aos" target="_blank" rel="noopener">anterior oblique subsystem (AOS)</a> and <a href="https://brookbushinstitute.com/courses/posterior-oblique-subsystem-pos" target="_blank" rel="noopener">posterior oblique subsystems (POS)</a> prevent excessive flexion, extension, <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> flexion, and rotation of the lumbar spine. The <a href="https://brookbushinstitute.com/courses/deep-longitudinal-subsystem" target="_blank" rel="noopener">deep longitudinal subsystem (DLS)</a> acts synergistically with the <a href="https://brookbushinstitute.com/courses/posterior-oblique-subsystem-pos" target="_blank" rel="noopener">POS</a> to extend the <a href="https://brookbushinstitute.com/courses/hip-joint" target="_blank" rel="noopener">hips</a> and <a href="https://brookbushinstitute.com/courses/knee" target="_blank" rel="noopener">knees</a>, stabilize the sacroiliac joint and eccentrically decelerate and/or isometrically stabilize the lumbar spine.
<ul>
 <li><a href="https://brookbushinstitute.com/courses/intrinsic-stabilization-subsystem" target="_blank" rel="noopener">Intrinsic Stabilization Subsystem (ISS)</a></li>
 <li><a href="https://brookbushinstitute.com/courses/posterior-oblique-subsystem-pos" target="_blank" rel="noopener">Posterior Oblique Subsystem (POS)</a></li>
 <li><a href="https://brookbushinstitute.com/courses/anterior-oblique-subsystem-aos" target="_blank" rel="noopener">Anterior Oblique Subsystem (AOS)</a></li>
 <li><a href="https://brookbushinstitute.com/courses/deep-longitudinal-subsystem" target="_blank" rel="noopener">Deep Longitudinal Subsystem (DLS)</a></li>
</ul>
<h2>Sample Program</h2>
<h3>Routine 1 (Month 1)</h3>
Goal: Lower Body Hypertrophy (Strength/Stability Supersets)
Acute Variables: 
<ul>
 <li>Load: Moderate (75-90% 1-RM)/Light (60-75% 1-RM)</li>
 <li>Reps/set: 6-12/6-12</li>
 <li>Sets/exercise (or circuits): 1-5 circuits</li>
 <li>Rest between exercises: 60 seconds</li>
 <li>Rest between Circuits: 1-3&#xA0;minutes (alternatively, can be performed in a circuit)</li>
 <li>Training time: 20 &#x2013; 60 minutes (excluding warm-up).</li>
</ul>
Strength/Stability Super-sets Routine: 
<ul>
 <li>Total Body: <a href="https://brookbushinstitute.com/videos/anterior-oblique-subsystem-integration-step-up-to-chest-press" target="_blank" rel="noopener">Step up to </a><a id="balance" data-tip="1190" target="_blank" href="/glossary-term/balance" class="glossary">Balance</a> to Press</li>
 <li> Strength: <a href="https://brookbushinstitute.com/videos/deadlift-with-posterior-pull" target="_blank" rel="noopener">Deadlift with </a><a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">Posterior</a> Pull</li>
 <li>Stability: <a href="https://brookbushinstitute.com/videos/wobble-lunge" target="_blank" rel="noopener">Transverse Plane Wobble Lunge</a></li>
 <li>Active Rest (Corrective, <a id="mobility" data-tip="1455" target="_blank" href="/glossary-term/mobility" class="glossary">mobility</a> not appropriate): <a href="https://brookbushinstitute.com/videos/posterior-tibialis-activation-progression-4">Tibialis </a><a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">Posterior</a> Activation</li>
</ul>
<h3>Routine 2 (Month 2)</h3>
Acute Variables: 
<ul>
 <li>Goal: Lower Body Max Strength/Power (Post-activation <a id="post-activation-potentiation" data-tip="1393" target="_blank" href="/glossary-term/post-activation-potentiation" class="glossary">Potentiation</a> Circuits)</li>
 <li>Load: (Heavy &gt; 85% of 1-RM) (Light &lt; 30% of 1-RM</li>
 <li>Reps/set: (1-5)(3-10)</li>
 <li>Sets/exercise (circuits): 2-6 circuits</li>
 <li>Rest between exercises: 1-2 minutes&#xA0;(note, exercise performed in circuit)</li>
 <li>Training Time: 20 &#x2013; 45 minutes (excluding warm-up).</li>
</ul>
Max Strength Circuit Routine: 
<ul>
 <li>Total Body: <a href="https://brookbushinstitute.com/videos/power-row-sled-pull" target="_blank" rel="noopener">Power Row Sled Pull</a></li>
 <li>Max Strength: <a href="https://brookbushinstitute.com/videos/back-squat" target="_blank" rel="noopener">Back Squat</a></li>
 <li>Power: <a href="https://brookbushinstitute.com/videos/depth-jump" target="_blank" rel="noopener">Depth Jump</a></li>
 <li>Active Rest (corrective/mobility not appropriate): <a href="https://brookbushinstitute.com/videos/tibialis-anterior-isolated-activation" target="_blank" rel="noopener">Tibialis </a><a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">Anterior</a> Activation</li>
</ul>

<h3>Kinesiology: Triple Extension</h3>
<h4>Hip Extension</h4>
<ul>
 <li>Prime Mover: <a href="https://brookbushinstitute.com/courses/gluteus-maximus" target="_blank" rel="noopener">Gluteus maximus</a></li>
 <li>Synergists: <a href="https://brookbushinstitute.com/courses/biceps-femoris" target="_blank" rel="noopener">Biceps femoris</a> (long head), semitendinosus, semimembranosus, and <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> head of <a href="https://brookbushinstitute.com/courses/adductors" target="_blank" rel="noopener">adductor magnus</a></li>
 <li>Antagonists: Psoas, iliacus, <a href="https://brookbushinstitute.com/courses/tensor-fascia-latae-tfl" target="_blank" rel="noopener">tensor fascia latae</a>, rectus femoris, <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> <a href="https://brookbushinstitute.com/courses/adductors" target="_blank" rel="noopener">adductors</a> (especially pectineus), and sartorius</li>
 <li>Neutralizers: Gluteus minimus, <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> fibers of gluteus medius, semitendinosus, and semimembranosus neutralize external rotation force of <a href="https://brookbushinstitute.com/courses/gluteus-maximus" target="_blank" rel="noopener">gluteus maximus</a></li>
 <li>Stabilizers: Deep rotators of the hip</li>
 <li>Fixators: <a href="https://brookbushinstitute.com/courses/intrinsic-stabilization-subsystem" target="_blank" rel="noopener">Intrinsic stabilization subsystem (ISS)</a>, <a href="https://brookbushinstitute.com/courses/anterior-oblique-subsystem-aos" target="_blank" rel="noopener">anterior oblique subsystem (AOS)</a>, <a href="https://brookbushinstitute.com/courses/posterior-oblique-subsystem-pos" target="_blank" rel="noopener">posterior oblique subsystem (POS)</a>, and <a href="https://brookbushinstitute.com/courses/deep-longitudinal-subsystem" target="_blank" rel="noopener">deep longitudinal subsystem (DLS)</a></li>
</ul>
<h4>Knee Extension</h4>
<ul>
 <li>Prime Mover: Quadriceps: vastus lateralis, vastus medialis, vastus intermedius, and rectus femoris</li>
 <li>Synergists: There are no true <a id="synergists" data-tip="1650" target="_blank" href="/glossary-term/synergists" class="glossary">synergists</a> of knee extension. However, the <a href="https://brookbushinstitute.com/courses/gluteus-maximus" target="_blank" rel="noopener">gluteus maximus</a> and <a href="https://brookbushinstitute.com/article/soleus" target="_blank" rel="noopener">soleus</a> can act as <a id="synergists" data-tip="1650" target="_blank" href="/glossary-term/synergists" class="glossary">synergists</a> during closed chain movements by &quot;pulling&quot; the tibia and femur posteriorly into knee extension.</li>
 <li>Antagonists: <a href="https://brookbushinstitute.com/courses/biceps-femoris" target="_blank" rel="noopener">Biceps femoris</a>, semimembranosus, semitendinosus, <a href="https://brookbushinstitute.com/courses/anatomy-articles/muscular-anatomy/popliteus/" target="_blank" rel="noopener">popliteus</a>, gastrocnemius, <a href="https://brookbushinstitute.com/courses/adductors" target="_blank" rel="noopener">gracilis</a>, and sartorius.</li>
 <li>Neutralizers: Careful <a id="balance" data-tip="1190" target="_blank" href="/glossary-term/balance" class="glossary">balance</a> between <a id="medial" data-tip="1568" target="_blank" href="/glossary-term/medial" class="glossary">medial</a> and <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> stabilizers of the knee must be maintained to prevent excessive internal or external rotation of the tibia. More complex relationships between synergistic pairs exist &#x2013; for example, the short head of the <a href="https://brookbushinstitute.com/courses/biceps-femoris" target="_blank" rel="noopener">biceps femoris</a> and vastus medialis obliquus are functional antagonists.</li>
 <li>Stabilizers:
 <ul>
 <li>Medial stabilizers: <a href="https://brookbushinstitute.com/courses/adductors" target="_blank" rel="noopener">Gracilis</a>, semitendinosus and semimembranosus, vastus medialis, popliteus, <a id="medial" data-tip="1568" target="_blank" href="/glossary-term/medial" class="glossary">Medial</a> gastrocnemius</li>
 <li>Lateral Stabilizers: <a href="https://brookbushinstitute.com/courses/gluteus-maximus" target="_blank" rel="noopener">Gluteus maximus</a>, <a href="https://brookbushinstitute.com/courses/tensor-fascia-latae-tfl" target="_blank" rel="noopener">TFL</a>, vastus lateralis via the iliotibial band, <a href="https://brookbushinstitute.com/courses/biceps-femoris" target="_blank" rel="noopener">biceps femoris</a>, <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">Lateral</a> gastrocnemius and plantaris</li>
 <li>Articularis genu</li>
 </ul>
 </li>
 <li>Fixators: <a href="https://brookbushinstitute.com/courses/intrinsic-stabilization-subsystem" target="_blank" rel="noopener">Intrinsic stabilization subsystem (ISS)</a>, <a href="https://brookbushinstitute.com/courses/anterior-oblique-subsystem-aos" target="_blank" rel="noopener">anterior oblique subsystem (AOS)</a>, <a href="https://brookbushinstitute.com/courses/posterior-oblique-subsystem-pos" target="_blank" rel="noopener">posterior oblique subsystem (POS)</a>, and <a href="https://brookbushinstitute.com/courses/deep-longitudinal-subsystem" target="_blank" rel="noopener">deep longitudinal subsystem (DLS)</a></li>
</ul>
<h4>Ankle Plantar Flexion</h4>
<ul>
 <li>Prime Mover: <a href="https://brookbushinstitute.com/courses/soleus" target="_blank" rel="noopener">Soleus</a> and gastrocnemius</li>
 <li>Synergists: Fibularis longus, fibularis brevis, <a href="https://brookbushinstitute.com/courses/tibialis-posterior" target="_blank" rel="noopener">tibialis posterior</a>, <a href="https://brookbushinstitute.com/courses/flexor-hallucis-longus-and-flexor-digitorum-longus" target="_blank" rel="noopener">flexor hallucis longus, flexor digitorum longus</a>, and plantaris</li>
 <li>Antagonists: <a href="https://brookbushinstitute.com/courses/tibialis-anterior" target="_blank" rel="noopener">Tibialis anterior</a>, <a href="https://brookbushinstitute.com/courses/extensor-hallucis-longus-and-extensor-digitorum-longus-fibularis-tertius" target="_blank" rel="noopener">extensor digitorum longus, extensor hallucis longus, and fibularis tertius</a></li>
 <li>Neutralizers: The <a href="https://brookbushinstitute.com/courses/tibialis-posterior" target="_blank" rel="noopener">tibialis posterior</a> and <a id="medial" data-tip="1568" target="_blank" href="/glossary-term/medial" class="glossary">medial</a> gastrocnemius neutralize the eversion force created by the <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> gastrocnemius and fibularis muscles.</li>
 <li>Stabilizers: Fibularis longus, fibularis brevis, <a href="https://brookbushinstitute.com/courses/tibialis-posterior" target="_blank" rel="noopener">tibialis posterior</a>, <a href="https://brookbushinstitute.com/courses/tibialis-anterior" target="_blank" rel="noopener">tibialis anterior</a>, <a href="https://brookbushinstitute.com/courses/flexor-hallucis-longus-and-flexor-digitorum-longus" target="_blank" rel="noopener">flexor hallucis longus, flexor digitorum longus</a>, <a href="https://brookbushinstitute.com/courses/extensor-hallucis-longus-and-extensor-digitorum-longus-fibularis-tertius" target="_blank" rel="noopener">extensor digitorum longus, extensor hallucis longus, and fibularis tertius</a></li>
 <li>Fixators: <a id="medial" data-tip="1568" target="_blank" href="/glossary-term/medial" class="glossary">Medial</a> and <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> stabilizers of the knee, quadriceps, and muscles of the foot.</li>
</ul>
<img title="Dr. Brent Brookbush demonstrating a wobble squat with a client" src="https://www.datocms-assets.com/25800/1649430273-wobble-squat.jpg" alt="A client performing a wobble squat">

Research Corner

<a id="prime-mover" data-tip="1662" target="_blank" href="/glossary-term/prime-mover" class="glossary">Prime mover</a> <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity during the barbell squat may not be affected by <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surfaces or loads. <a id="prime-mover" data-tip="1663" target="_blank" href="/glossary-term/prime-mover" class="glossary">Prime movers</a> are defined as the quadriceps and gluteal complex (gluteus maximus and gluteus medius), and research has investigated various <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surfaces including foam pads, Reebok Core&#xAE; Boards, <a id="balance" data-tip="1190" target="_blank" href="/glossary-term/balance" class="glossary">balance</a> boards, BOSU&#xAE; balls, and <a id="balance" data-tip="1190" target="_blank" href="/glossary-term/balance" class="glossary">balance</a> cones (1-5). Most research investigating vastus medialis and vastus lateralis activity demonstrate that training surface does not have a significant effect on activity (2-5). However, a study using novice exercisers found a significant increase in vastus medialis and vastus lateralis <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity when a foam pad was added to isometric squats (1). This study could be compared to a study using experienced exercises and a similar foam pad, demonstrating no change in <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity (4). This may imply novice exercisers exhibit an increase in EMG activity to accommodate <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surfaces, however, experience reduces the need for this increase (1,4). Only one study was found comparing the glute complex activity of experienced lifters on stable and <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surfaces, and no significant difference in <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity was noted (3). In summary, research suggests <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surfaces have little effect on <a id="prime-mover" data-tip="1662" target="_blank" href="/glossary-term/prime-mover" class="glossary">Prime mover</a> <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity for experienced lifters but may increase <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity in novice lifters. More research is needed to determine how <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surfaces contribute to the increases in performance noted above; for example, increased coordination, <a id="balance" data-tip="1190" target="_blank" href="/glossary-term/balance" class="glossary">balance</a>, and reaction time.
<a id="stabilizers" data-tip="1653" target="_blank" href="/glossary-term/stabilizers" class="glossary">Stabilizer</a> <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity during a barbell squat may be affected by <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> loads, but probably not <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surfaces. Research has investigated lower-extremity stabilizers including the <a href="https://brookbushinstitute.com/courses/biceps-femoris" target="_blank" rel="noopener">bicep femoris</a>, <a href="https://brookbushinstitute.com/courses/tibialis-anterior" target="_blank" rel="noopener">tibialis anterior</a>, gastrocnemius, and <a href="https://brookbushinstitute.com/courses/soleus" target="_blank" rel="noopener">soleus</a>, as well as core muscles including the <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/courses/erector-spinae" target="_blank" rel="noopener">erector spinae</a>, and multifidus (2-7). A study by Lawrence et al. demonstrated that weight plates suspended from a barbell by bands resulted in a significant increase in <a href="https://brookbushinstitute.com/courses/external-obliques" target="_blank" rel="noopener">external oblique</a>, <a href="https://brookbushinstitute.com/courses/rectus-abdominis-pyramidalis" target="_blank" rel="noopener">rectus abdominis</a>, and <a href="https://brookbushinstitute.com/courses/soleus" target="_blank" rel="noopener">soleus</a> <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity (6), and Ditroilo et al. demonstrated that squats using a water-filled tube significantly increased <a href="https://brookbushinstitute.com/courses/external-obliques" target="_blank" rel="noopener">external oblique</a> and multifidus <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity (7). The research studies mentioned above also demonstrated that <a id="stabilizers" data-tip="1653" target="_blank" href="/glossary-term/stabilizers" class="glossary">Stabilizer</a> and core <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity were not significantly affected by <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surfaces (2-5). One study by Saeterbakken et al. demonstrated an increase in <a href="https://brookbushinstitute.com/courses/soleus" target="_blank" rel="noopener">soleus</a> activity using a BOSU&#xAE; ball during a squat, but the increase in activity did not reach clinical significance (5). These studies suggest that <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> loads have a much larger effect on the <a id="stabilizers" data-tip="1653" target="_blank" href="/glossary-term/stabilizers" class="glossary">Stabilizer</a> and core <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity than <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surfaces, and if the goal is an increase in <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity then <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> loads may be preferred. Again, more research is needed on <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surface and <a id="stability-training" data-tip="1174" target="_blank" href="/glossary-term/stability-training" class="glossary">balance training</a> to determine the factors contributing to the increases in performance.
<h4>Summary</h4>
<ul>
 <li>Adding <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surfaces to a <a href="https://brookbushinstitute.com/video/back-squat" target="_blank" rel="noopener">squat</a> may increase <a id="prime-mover" data-tip="1662" target="_blank" href="/glossary-term/prime-mover" class="glossary">prime mover</a> activity for inexperienced lifters.</li>
 <li>Adding <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surfaces to a <a href="https://brookbushinstitute.com/video/back-squat" target="_blank" rel="noopener">squat</a> may not alter EMG activity for stabilizers or <a id="prime-mover" data-tip="1663" target="_blank" href="/glossary-term/prime-mover" class="glossary">prime movers</a> in experienced lifters.</li>
 <li>Adding <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> loads to a <a href="https://brookbushinstitute.com/video/back-squat" target="_blank" rel="noopener">squat</a> significantly increases <a id="stabilizers" data-tip="1653" target="_blank" href="/glossary-term/stabilizers" class="glossary">stabilizer</a> and core <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity for experienced and inexperienced lifters.</li>
 <li>More research is needed to determine how <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surfaces contribute to the increases in performance noted above; for example, increased coordination, <a id="balance" data-tip="1190" target="_blank" href="/glossary-term/balance" class="glossary">balance</a>, reaction time.</li>
</ul>

Muscle activity during squats has been compared to the lunge and Bulgarian split squat (4, 8-12). Stuart et al. compared <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">Muscle</a> activity during squats and lunges using a 50-pound barbell; demonstrating higher quadriceps and hamstring <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">Muscle</a> activity during the lunge (8). However, a study by DeForest et al. demonstrated that when lunges were performed with half the weight used for the squat, lunges exhibited similar <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">Muscle</a> activity for the quadriceps and lower activity for the <a href="https://brookbushinstitute.com/courses/biceps-femoris" target="_blank" rel="noopener">biceps femoris</a> (9). In studies comparing squats to the Bulgarian split-squat, EMG activity for the vastus medialis and vastus lateralis were similar (9, 10), even when performed on an Airex pad (<a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surface) (4). Squat, lunges,&#xA0;and Bulgarian split-squats demonstrated similar <a href="https://brookbushinstitute.com/courses/erector-spinae" target="_blank" rel="noopener">erector spinae</a> activity, however, the Bulgarian split-squat elicited higher <a href="https://brookbushinstitute.com/courses/external-obliques" target="_blank" rel="noopener">external oblique</a>, gluteus medius, and <a href="https://brookbushinstitute.com/courses/gluteus-maximus" target="_blank" rel="noopener">gluteus maximus</a> activity (4, 9-12). <a href="https://brookbushinstitute.com/courses/biceps-femoris" target="_blank" rel="noopener">Biceps femoris</a> activity was similar for the Bulgarian split squat and squats when using heavier external loading for the squat, but when using loads of 3-10 repetition maximums (RM) for each exercise, more <a href="https://brookbushinstitute.com/courses/biceps-femoris" target="_blank" rel="noopener">biceps femoris</a> activity was exhibited during the Bulgarian split squat (4, 10-12). One study by DeForest et al. (9) compared <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">Muscle</a> activity during the Bulgarian split-squat and lunges, with the Bulgarian split-squat requiring similar quadriceps <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">Muscle</a> activity and higher hamstring <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">Muscle</a> activity. These studies imply that careful attention to the load used during the study is important for developing sound conclusions. <a id="prime-mover" data-tip="1662" target="_blank" href="/glossary-term/prime-mover" class="glossary">Prime mover</a> activity is likely similar during all exercises when loads are adjusted to ensure failure within similar rep ranges. Hip and trunk <a id="stabilizers" data-tip="1653" target="_blank" href="/glossary-term/stabilizers" class="glossary">stabilizer</a> <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">Muscle</a> activity is higher during lunges and Bulgarian split-squats when compared to squats. Bulgarian split squats exhibited the most <a href="https://brookbushinstitute.com/courses/biceps-femoris" target="_blank" rel="noopener">biceps femoris</a> activity, and the lunge exhibited the least, which may imply Bulgarian split squats should be avoided due to the propensity of the <a href="https://brookbushinstitute.com/courses/biceps-femoris" target="_blank" rel="noopener">biceps femoris</a> to be over-active in those individuals exhibiting signs of <a href="https://brookbushinstitute.com/courses/lower-leg-dysfunction" target="_blank" rel="noopener">Lower-Extremity Dysfunction (LED)</a>. In summary, the reduction in <a href="https://brookbushinstitute.com/courses/biceps-femoris" target="_blank" rel="noopener">biceps femoris</a> activity and increase in core and hip <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">Muscle</a> activity during lunges may imply this is an ideal <a id="exercise-progression" data-tip="1184" target="_blank" href="/glossary-term/exercise-progression" class="glossary">progression</a> from squats.
<img src="https://www.datocms-assets.com/25800/1649430509-wobble-lunge.jpg" title="Dr. Brent Brookbush demonstrating a wobble lunge" alt="The wobble lunge exercise">

<a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">Muscle</a> activity during the squat has also been compared to the step-up and single-leg squat (13, 14). These exercises are discussed separately from the Bulgarian split-squat and lunge&#xA0;because the step-up and single-leg squat are truly unilateral; performed on one limb without <a id="base-of-support" data-tip="1197" target="_blank" href="/glossary-term/base-of-support" class="glossary">support</a> from the other. When no external load is added, the step-up requires twice as much glute complex activity as the squat, and the single-leg squat requires significantly more glute complex activity than the step-up (13). When a barbell was used to add external load to the squat and single-leg squat, the squat exhibited similar gluteal complex and semitendinosus activity, but higher quadriceps, <a href="https://brookbushinstitute.com/courses/erector-spinae" target="_blank" rel="noopener">erector spinae</a>, and <a href="https://brookbushinstitute.com/courses/biceps-femoris" target="_blank" rel="noopener">bicep femoris</a> <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">Muscle</a> activity (14). It is possible that during these loaded studies the gluteal complex reached a recruitment threshold, that reduced the differences noted when larger loads were used (13, 14). Interestingly, band resisted abduction around the knee increased gluteal complex <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">Muscle</a> activity during the unweighted squat&#xA0;but decreased gluteal complex <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">Muscle</a> activity during the step-up and single-leg squat (13). This is likely due to the step-up and single-leg squat being open chain movements, and the gluteal complex being unable to contribute to abduction when the pelvis was not fixed (by the other leg on the ground). That is, the only means of resisting a valgus force at the knee during an &quot;open-chain&quot; lower extremity exercise is ankle eversion because a planted foot on the ground creates a stable <a id="base-of-support" data-tip="1196" target="_blank" href="/glossary-term/base-of-support" class="glossary">base</a> to &quot;push&quot; from. In summary, an increase in gluteal complex <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">Muscle</a> activity may be achieved by progressing from squats to step-ups to single-leg squats; however, differences in EMG activity decrease when external loads are used. Further, <a id="a-band" data-tip="1347" target="_blank" href="/glossary-term/a-band" class="glossary">a band</a> around the knees resisted abduction only increases gluteal complex activity during close chain activities.
<img src="https://www.datocms-assets.com/25800/1647306024-squat-with-mini-band.jpg" title="Squatting with a miniband above the knees to increase glute complex activity " alt="Squat with miniband">

EMG activity has been compared during various <a id="unilateral" data-tip="1551" target="_blank" href="/glossary-term/unilateral" class="glossary">unilateral</a> lower-extremity exercises, on stable and <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surfaces (4, 15, 16). Krause et al. demonstrated EMG activity during a body-weight lunge was 9 - 22% maximal voluntary isometric contraction (MVIC) for the rectus femoris, hamstrings, gluteus medius, <a href="https://brookbushinstitute.com/courses/gluteus-maximus" target="_blank" rel="noopener">gluteus maximus</a>, and <a href="https://brookbushinstitute.com/courses/adductors">adductor longus</a> (15). Another study by Krause et al. demonstrated EMG activity during a body-weight single-leg squat was 50% MVIC for the gluteus medius (16). These same studies demonstrated that when an <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surface was introduced, %MVIC increased for the lunge, but not for the single-leg squat (15, 16). A study by Andersen et al. reported that %MVIC for a loaded Bulgarian split squat was 140% MVIC for the <a href="https://brookbushinstitute.com/courses/biceps-femoris" target="_blank" rel="noopener">bicep femoris</a>, <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 oblique</a>, and between 70-90% MVIC for the rectus femoris, vastus medialis, vastus lateralis, and <a href="https://brookbushinstitute.com/courses/erector-spinae" target="_blank" rel="noopener">erector spinae</a> (4). The much higher %MVIC in these studies is likely due to the use of external load; however, it is interesting to note that adding an <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> environment to the loaded Bulgarian split-squat actually reduced %MVIC of the <a href="https://brookbushinstitute.com/courses/erector-spinae" target="_blank" rel="noopener">erector spinae</a> and <a href="https://brookbushinstitute.com/courses/biceps-femoris" target="_blank" rel="noopener">biceps femoris</a>. The reduction in activity when adding an <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> environment is likely due to an inability to produce the same amount of force, i.e. lift the same load, or lift the same load at the same speed. In summary, <a id="exercise-progression" data-tip="1184" target="_blank" href="/glossary-term/exercise-progression" class="glossary">progression</a> from a lunge to single leg squat may increase glute complex activity, adding an <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surface to body-weight exercise is likely to increase EMG activity; whereas, adding <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surfaces to loaded exercise may reduce the capacity to produce force. Consideration of the phase of training and the client&apos;s goal may dictate whether <a id="stability" data-tip="1191" target="_blank" href="/glossary-term/stability" class="glossary">stability</a> or load is the appropriate <a id="exercise-progression" data-tip="1184" target="_blank" href="/glossary-term/exercise-progression" class="glossary">progression</a>. (Note, the Bulgarian split squat was omitted for the reasons mentioned above).
<img title="Dr. Brent Brookbush demonstrating a lateral lunge with front rack" src="https://www.datocms-assets.com/25800/1649424090-lateral-lunge-with-front-rack-squat.jpg" alt="A lateral lunge in a front rack position">

Comparing the Unilateral Lower Body Exercise on Stable and Unstable Surfaces

<ul>
 <li>The reduction in biceps femoris activity and increase in core and hip <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity may imply lunges are a better <a id="exercise-progression" data-tip="1184" target="_blank" href="/glossary-term/exercise-progression" class="glossary">progression</a> from squats than Bulgarian split squats.</li>
 <li>Gluteal complex and core <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity increase as you progress from squats to step-ups to lunges to single-leg squats/deadlifts; however, differences in EMG activity decrease when external loads are added.</li>
 <li>Adding an <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> environment to body-weight exercise is likely to increase EMG activity; whereas, adding <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> environments to loaded exercise may reduce the capacity to produce force.</li>
 <li>Band resisted abduction around the knees only increases gluteal complex activity during squats.
 <ul>
 <li>Note: Bulgarian split squats are not recommended due to the increased hamstring activity, stress on commonly restricted hip flexors, and potential strain on the knee.</li>
 </ul>
 </li>
</ul>

The leg/triple extension <a id="exercise-progression" data-tip="1182" target="_blank" href="/glossary-term/exercise-progression" class="glossary">progressions</a> discussed below are built upon several &quot;general progressions&quot; that can be applied to any exercise. In this course, these <a id="exercise-progression" data-tip="1182" target="_blank" href="/glossary-term/exercise-progression" class="glossary">progressions</a> were applied to the movement pattern in conjunction with the <a id="relative-flexibility" data-tip="1654" target="_blank" href="/glossary-term/relative-flexibility" class="glossary">relative flexibility</a> <a id="exercise-progression" data-tip="1182" target="_blank" href="/glossary-term/exercise-progression" class="glossary">progressions</a> and then edited based on feasibility and effectiveness.
<table>
 <tbody>
 <tr>
 <td>Load</td>
 <td>Surface</td>
 <td>Stability Progression</td>
 </tr>
 <tr>
 <td>Type
 <ul>
 <li>Barbell</li>
 <li>Dumbbell/Kettlebell</li>
 <li>Earthquake Bar (band suspended weights)</li>
 </ul>
 Position
 <ul>
 <li>Held at sides</li>
 <li>Back loaded</li>
 <li>Front rack</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>Airex Pad</li>
 <li>Half-Foam Roll</li>
 <li>Uni-planer <a id="balance" data-tip="1190" target="_blank" href="/glossary-term/balance" class="glossary">Balance</a> Board</li>
 <li>PB Disk</li>
 <li>Bosu Flat Side Up</li>
 <li>Etc.</li>
 </ul>
 </td>
 <td>
 <ol>
 <li>Ball Wall Squats</li>
 <li>Squats</li>
 <li>Step-Ups</li>
 <li>Lunges</li>
 </ol>
 </td>
 </tr>
 </tbody>
</table>

Stability Progressions

The leg/triple extension <a id="exercise-progression" data-tip="1182" target="_blank" href="/glossary-term/exercise-progression" class="glossary">progressions</a> discussed below are built upon several &quot;general progressions&quot; that can be applied to any exercise. In this course, these <a id="exercise-progression" data-tip="1182" target="_blank" href="/glossary-term/exercise-progression" class="glossary">progressions</a> were applied to the movement pattern in conjunction with the <a id="relative-flexibility" data-tip="1654" target="_blank" href="/glossary-term/relative-flexibility" class="glossary">relative flexibility</a> <a id="exercise-progression" data-tip="1182" target="_blank" href="/glossary-term/exercise-progression" class="glossary">progressions</a> and then edited based on feasibility and effectiveness.
<table>
 <tbody>
 <tr>
 <td>Load</td>
 <td>Surface</td>
 <td>Stability Progression</td>
 </tr>
 <tr>
 <td>Type
 <ul>
 <li>Barbell</li>
 <li>Dumbbell/Kettlebell</li>
 <li>Earthquake Bar (band suspended weights)</li>
 </ul>
 Position
 <ul>
 <li>Held at sides</li>
 <li>Back loaded</li>
 <li>Front rack</li>
 </ul>
 </td>
 <td>
 <ul>
 <li>Airex Pad</li>
 <li>Half-Foam Roll</li>
 <li>Uni-planer <a id="balance" data-tip="1190" target="_blank" href="/glossary-term/balance" class="glossary">Balance</a> Board</li>
 <li>PB Disk</li>
 <li>Bosu Flat Side Up</li>
 <li>Etc.</li>
 </ul>
 </td>
 <td>
 <ol>
 <li>Ball Wall Squats</li>
 <li>Squats</li>
 <li>Step-Ups</li>
 <li>Lunges</li>
 </ol>
 </td>
 </tr>
 </tbody>
</table>
<h4></h4>
<h4>Key points:</h4>
<ul>
 <li>It is often helpful to cue hips forward, or a &quot;hip thrust&quot; on the concentric phase (instead of &quot;lifting up&quot;). The &quot;hip thrust&quot; cue seems to reduce erector spinae recruitment, reduce excessive arching of the lumbar spine, and increase glute activation.</li>
 <li>There are an enormous amount of secondary references on &quot;ideal squat form&quot;. The squat <a id="posture" data-tip="1660" target="_blank" href="/glossary-term/posture" class="glossary">form</a> recommended in these courses is based on &quot;an absence of any obvious movement impairment&quot;. That is <a href="https://brookbushinstitute.com/video/overhead-squat-assessment-5-feet-turn-out-breakdown" target="_blank" rel="noopener">feet turn out</a>, <a href="https://brookbushinstitute.com/video/overhead-squat-assessment-6-knees-bow-in-breakdown" target="_blank" rel="noopener">knees bow in</a>, <a href="https://brookbushinstitute.com/video/overhead-squat-assessment-7-knees-bow-out" target="_blank" rel="noopener">knees bow out</a>, <a href="https://brookbushinstitute.com/video/overhead-squat-assessment-8-excessive-forward-lean" target="_blank" rel="noopener">excessive forward lean</a> and an <a href="https://brookbushinstitute.com/video/overhead-squat-assessment-9-anterior-pelvic-tilt-excessive-lordosis" target="_blank" rel="noopener">anterior pelvic tilt</a> may be correlated with pain, dysfunction, and/or increased risk of future injury. For more information please see our courses on the <a href="https://brookbushinstitute.com/courses/solutions-table-overhead-squat-assessment" target="_blank" rel="noopener">Overhead Squat Assessment</a>.</li>
 <li>Bulgarian split squats are not recommended due to an increase in <a href="https://brookbushinstitute.com/courses/biceps-femoris" target="_blank" rel="noopener">biceps femoris</a> activity, compensation around commonly restricted <a href="https://brookbushinstitute.com/courses/tensor-fascia-latae-tfl" target="_blank" rel="noopener">hip flexors</a>, and potential strain on the <a href="https://brookbushinstitute.com/courses/knee" target="_blank" rel="noopener">knee</a> of the back leg.</li>
 <li>Single-leg Touchdowns are discussed in <a href="https://brookbushinstitute.com/courses/deadlift-progression" target="_blank" rel="noopener">Deadlift Progressions</a></li>
</ul>

Points on Form

Our recommendation for feet hip width and parallel is based on reinforcing form/posture that is absent of signs correlated with pain and injury, including feet flatten (pes planus), feet turn out, knees bow out (knee varus), and knees bow in (knee valgus). Further, our recommendations are likely to ensure the largest transfer to daily activity and sport; that is, you do not walk, run, or jump, with legs wide, and feet turned out. &#x201C;Feet parallel and hip width&#x201D; implies that the 2nd toe is pointing forward and underneath the <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> iliac spine (ASIS). The reasons for this are that the 2nd toe aligns with the center of the foot, and the ASIS is located <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a>, and nearly in alignment, with the center of rotation of the hip joints. The greater trochanter, which people often call &#x201C;their hips&#x201D;, is located at the end of the femoral neck, which is several centimeters <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> to the center of rotation of your hip joints. We understand that &#x201C;shoulder width&#x201D; may feel more comfortable and may be acceptable for some individuals. However, we also suggest that a lack of comfort with ideal alignment may be a sign of less-than-optimal <a id="mobility" data-tip="1455" target="_blank" href="/glossary-term/mobility" class="glossary">mobility</a> or recruitment, and a corrective exercise/movement prep warm-up should be recommended. Powerlifters may adopt a foot position that allows them to move the most weight, but this should be viewed as &#x201C;practicing for a sport.&#x201D; Just as depth jumps are recommended for basketball players looking to increase their vertical but are not recommended for every individual who exercises; a powerlifters squat technique may be essential for their sport, but not ideal for most athletes and/or the general public.

Foot Position

Videos and Progressions

Ideally, squats would be performed while maintaining a tibia angle and a torso angle that are close to parallel. This body position will result in ample motion of the hip, knees, and ankles; resulting in less stress on any one joint, and maximal recruitment of the lower extremity muscles. However, this assertion does have two important implications. First, it implies that a &#x201C;forward lean&#x201D; of the torso is necessary. It is impossible to squat with a completely vertical torso (without assistance from a machine). The result would be the body&#x2019;s <a id="center-of-mass-gravity" data-tip="1186" target="_blank" href="/glossary-term/center-of-mass-gravity" class="glossary">center of mass</a> (near the core) traveling behind the <a id="base-of-support" data-tip="1195" target="_blank" href="/glossary-term/base-of-support" class="glossary">base of support</a> (feet) and falling over backward. There is also some research to demonstrate that a &#x201C;forward lean&#x201D; of the torso increases gluteus maximus recruitment. Second, the knees must pass the toes as an individual descends into a half-squat or deeper. No research suggests that the knees passing the toes increases the risk of knee pain or injury. However, the knees passing the toes will require more dorsiflexion, and increasing dorsiflexion allows for more recruitment of the calf complex. Further, more dorsiflexion aids in shifting the body&#x2019;s <a id="center-of-mass-gravity" data-tip="1186" target="_blank" href="/glossary-term/center-of-mass-gravity" class="glossary">center of mass</a> anteriorly, making it easier to maintain any external load in a more biomechanically advantageous position.

Knees Over Toes (Tibia and Torso Parallel)

Cues should be developed based on a movement professional&#x2019;s desire to optimize form/posture, and any cue should be communicated to the client or patient, based on their needs, in a way that makes sense to them. Although cues like &#x201C;head up&#x201D;, &#x201C;shoulders back&#x201D;, and &#x201C;chest up&#x201D; may be appropriate for someone exhibiting signs of upper extremity dysfunction, they should not be cued to the extremes of these positions, nor should they be recommended to someone who does not exhibit signs of upper body dysfunction. Although BI professionals use these examples of cues when appropriate, we have also seen them result in some dogmatic thinking. For example, &#x201C;chest up&#x201D; is an appropriate cue, until &#x201C;chest up&#x201D; results in excessive thoracic or lumbar extension, and &#x201C;shoulder blades down and back&#x201D; is a good cue until <a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a> scapula <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> tipping is exceeded to result in excessive retraction. And, &#x201C;head up&#x201D; is a great cue until &#x201C;head up&#x201D; results in excessive cervical extension rather than the cervical spine maintaining neutral alignment with the torso, and the eyes naturally following a path from straight ahead during standing, to the bottom of a mirror or the floor 1-2 meters in front of the individual at the bottom of the squat. In short, it is our recommendation, that cuing is appropriately modified for the client, and is used to find neutral (<a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a>) alignment, not extreme positions. This recommendation may be especially appropriate regarding the alignment of the torso, scapula, cervical spine, and head.

Head, Torso, and Scapula Neutral

Target Leg: The length of the client&#x2019;s or patient&#x2019;s stride can be determined by the <a id="posture" data-tip="1660" target="_blank" href="/glossary-term/posture" class="glossary">form</a> achieved during the bottom position of the lunge. In the bottom position, the alignment of the target leg and torso should be similar to the ideal alignment achieved during the bottom position of a squat. That is, from a <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> view of the target leg side, the bottom position of a lunge should look like the bottom position of a squat (with the other leg acting as a <a id="base-of-support" data-tip="1197" target="_blank" href="/glossary-term/base-of-support" class="glossary">support</a>). This is true regardless of whether the lunge is performed in the sagittal, frontal, or transverse planes, regardless of the type or position of load, and regardless of whether the lunge is incorporated into a total body exercise (<a id="integration" data-tip="1473" target="_blank" href="/glossary-term/integration" class="glossary">integrated</a> exercise).
<ul>
 <li>Ideal Target Leg (e.g. squat) Alignment:
 <ul>
 <li>2nd toe pointing forward and under the ASIS</li>
 <li>Ankles, knees, and hips in alignment</li>
 <li>Pelvis neutral (absence of <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> or <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> pelvic tilt)</li>
 <li>Tibia and Torso Neutral</li>
 <li>Torso, scapula, and head in neutral alignment</li>
 </ul>
 </li>
</ul>
Non-target Leg: The femur of the non-target leg should be near vertical in the bottom position of a sagittal plane or transverse plane lunge. During a frontal plane lunge the foot of the non-target leg should be parallel and nearly in frontal plane alignment with the foot of the target leg, the knee should maintain near terminal extension, and it is often important to cue the client or patient to &#x201C;sit back&#x201D; to ensure the hips translate posteriorly as seen during <a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a> squat mechanics. It may be helpful to think of a frontal plane lunge as a squat with the non-target leg straight and out to the side.
&#xA0;
<ul>
 <li>No Vertical Torso: A common mistake during a lunge is maintaining a vertical torso. This reduces contribution from the gluteus maximus and increases the load on the knee of the non-target leg.</li>
</ul>

Stride Length During a Lunge

Holding a load in a front rack position can be a great <a id="exercise-progression" data-tip="1184" target="_blank" href="/glossary-term/exercise-progression" class="glossary">progression</a> for squat, step-up, and lunge variations. By holding the weight in front of the body, the load creates larger moment arms relative to the core and lower extremities, resulting in more resistance to stabilize and overcome. Further, practicing the Front Rack Position can be used to increase upper extremity <a id="stability" data-tip="1191" target="_blank" href="/glossary-term/stability" class="glossary">stability</a> and isometric strength.
<h4>Front Rack Instructions:</h4>
<ul>
 <li>Firmly Grip the Resistance: Firmly grip the weights/load in the hands (dumbbells, kettlebells, sandbags, slosh pipes, etc.).</li>
 <li>Stabilize the Scapula: Protract and depress the scapula.</li>
 <li>Cradle the Weight: Attempt to maintain the forearms near vertical by cueing elbows high and shoulder width (the load should be &#x201C;carried&#x201D; by the arms; not &#x201C;curled&#x201D;),</li>
 <li>Support the Weight: Cue enough elbow flexion to ensure some of the load is supported by the upper arm and/or <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> shoulder.</li>
 <li>Barbells are Not Recommended (unless required by the sport). Front rack position with a barbell tends to promote <a id="hypermobility" data-tip="1677" target="_blank" href="/glossary-term/hypermobility" class="glossary">hypermobility</a> in the hands, wrists, and elbows and may increase the risk of pain and dysfunction.</li>
</ul>

Front Rack Position

<ol>
 <li>Ball Wall Squat</li>
 <li>Body Weight Squat</li>
 <li>Body Weight Squat Unstable</li>
 <li>Back Squat</li>
 <li>Front Squat</li>
 <li>Wobble Squat</li>
</ol>

Squat Stability Videos and Progression

Squat Form and Modifications

Back Squat

Front Squat

Wobble Squat

Generally, <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a> surfaces are not recommended for step-ups, and great care should be taken with back loaded resistance. Although the height of a step-up may seem relatively low, falling in the direction of the stance leg with or without load can be hazardous.
<ol>
 <li>Alternating Step-up</li>
 <li>Single-Leg Step-up
 <ul>
 <li>Sagittal</li>
 <li>Frontal</li>
 <li>Transverse</li>
 </ul>
 </li>
 <li>Step-Up to <a id="balance" data-tip="1190" target="_blank" href="/glossary-term/balance" class="glossary">Balance</a>
 <ul>
 <li>Sagittal</li>
 <li>Frontal</li>
 <li>Transverse</li>
 </ul>
 </li>
</ol>

Step-Up Stability Videos and Progressions

Step-Ups

Load Progressions:
<ol>
 <li>Holding a weight at the sides</li>
 <li>Front-loaded</li>
 <li><a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">Unstable</a> load (weights suspended from a barbell with bands, or using liquid-filled tubes)</li>
</ol>
<h4>Motion Progressions:</h4>
<ol>
 <li>Static lunge
 <ul>
 <li>Frontal plane</li>
 </ul>
 </li>
 <li>Static lunge <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a>
 <ul>
 <li>Frontal plane</li>
 </ul>
 </li>
 <li>Dynamic lunge
 <ul>
 <li>Reverse</li>
 <li>Forward</li>
 <li>Frontal plane</li>
 <li>Transverse plane</li>
 </ul>
 </li>
 <li>Dynamic lunge to single-leg <a id="balance" data-tip="1190" target="_blank" href="/glossary-term/balance" class="glossary">balance</a>
 <ul>
 <li>Reverse</li>
 <li>Forward</li>
 <li>Frontal plane</li>
 <li>Transverse plane</li>
 </ul>
 </li>
 <li>Dynamic lunge to single leg <a id="balance" data-tip="1190" target="_blank" href="/glossary-term/balance" class="glossary">balance</a> <a id="stability" data-tip="1194" target="_blank" href="/glossary-term/stability" class="glossary">unstable</a>
 <ul>
 <li>Reverse</li>
 <li>Forward</li>
 <li>Frontal plane</li>
 <li>Transverse plane</li>
 </ul>
 </li>
</ol>

Lunge Stability Progressions

Sagittal Plane Lunge

Frontal Plane (Lateral) Lunge

Front Rack Lateral Lunge:

Transverse Plane Lunge

Wobble Lunge

<ol>
 <li>Park, J. K., Lee, D. Y., Kim, J. S., Hong, J. H., You, J. H. and Park, I. M. (2015) Effects of visibility and types of the ground surface on the muscle activities of the vastus medialis oblique and vastus lateralis. Journal of Physical Therapy Sciences, 27, 2435-2437</li>
 <li>Han, D., Nam, S., Song, J., Lee, W. and Kang, T. (2017) The effect of knee flexion angles and ground conditions on the muscle activation of the lower extremity in the squat position. The Journal of Physical Therapy Science, 29, 1852-1855.</li>
 <li>Li, Y., Cao, C. and Chen, X. (2013) Similar electromyographic activities of lower limbs between squatting on a reebok core board and ground. Journal of Strength and Conditioning Research, 27(5), 1349-1353</li>
 <li>Andersen, V., Fimland, M. S., Brennset, O., Haslestad, L. R., Lundteigen, M. S., Skalleberg, K. and Saeterbakken, A. H. (2014) Muscle activation and strength in squat and Bulgarian squat on stable and unstable surface. Sports Medicine, 35, 1196-1202</li>
 <li>Saeterbakken, A. H. and Fimland, M. S. (2013) Muscle force output and electromyographic activity in squats with various unstable surfaces. The Journal of Strength and Conditioning Research, 27(1), 130-136</li>
 <li>Lawrence, M. A. and Carlson, L. A. (2015) Effects of an unstable load on force and muscle activation during a parallel back squat. Journal of Strength and Conditioning, 29(10), 2949-2953</li>
 <li>Ditroilo, M., O'Sullivan, R., Harnan, B., Crossey, A., Gillmor, B., Dardis, W. and Grainger, A. (2018) Water-filled training tubes increase core muscle activation and somatosensory control of balance during squat. Journal of Sports Sciences, 36(17), 2002-2008</li>
 <li>Stuart, M. J., Meglan, D. A., Lutz, G. E., Growney, E. S. and An, K. N. (1996) Comparison of intersegmental tibiofemoral joint forces and muscle acdtivity during various closed kinetic chain exercises. The American Journal of Sports Medicine, 24(6), 792-799</li>
 <li>DeForest, B. A., Cantrell, G. S. and Schilling, B. K. (2014) Muscle activity in single- vs. double-leg squats. International Journal of Exercise Science, 7(4), 302-310</li>
 <li>Jones, M. T., Ambegaonkar, J. P., Nindl, B. C., Smith, J. A. and Headley, S. A. (2012) Effects of unilateral and bilateral lower-body heavy resistance exercise on muscle activity and testosterone responses. The Journal of Strength and Conditioning Research, 26(4), 1094-1100</li>
 <li>McCurdy, K., O'Kelley, E., Kutz, M., Langford, G., Ernest, J. and Torres, M. (2010) Comparison of lower extremity EMG between the 2-leg squat and modified single-leg squat in female athletes. Journal of Sport Rehabilitation, 19, 57-70</li>
 <li>McCurdy, K., Walker, J. and Yuen, D. Gluteus maximus and hamstring activation during selected weight-bearing resistance exercises. Journal of Strength and Conditioning Research,</li>
 <li>Lubahn, A. J., Kernozek, T. W., Tyson, T. L., Merkitch, K. W., Reutemann, P. and Chestnut, J. M. (2011) Hip muscle activation and knee frontal plane motion during weight bearing therapeutic exercises. The International Journal of Sports Physical Therapy, 6(2), 92-103</li>
 <li>Eliassen, W., Saeterbakken, A. H. and van den Tillaar, R. (2018) Comparison of bilateral and unilateral squat exercises on barbell kinematics and muscle activation. The International Journal of Sports Physical Therapy, 13(5), 871-881</li>
 <li>Krause, D. A., Elliott, J. J., Fraboni, D. F., McWilliams, T. J., Rebhan, R. L. and Hollman, J. H. (2018) Electromyography of the hip and thigh muscles during two variations of the lunge exercise: a cross-sectional study. The International Journal of Sports Physical Therapy, 13(2), 137-14</li>
 <li>Krause, D. A., Jacobs, R. S., Pilger, K. E., Sather, B. R., Sibunka, S. P. and Hollman, J. H. (2009) Electromyographic analysis of the gluteus medius in five weight-bearing exercises. Journal of Strength and Conditioning Research, 23(9), 2689-2694.</li>
 <li>DiStefano, L. J., Blackburn, J. T., Marshall, S. W. and Padua, D. A. (2009) Gluteal muscle activation during common therapeutic exercises. Journal of Orthopaedic and Sports Physical Therapy, 39(7), 532-540</li>
 <li>Boren, K., Conrey, C., Le Coguic, J., Paprocki, L., Voight, M. and Robinson, T. K. (2011) Electromyographic analysis of gluteus medius and gluteus maximus during rehabilitation exercises. The International Journal of Sports Physical Therapy, 6(3), 206-223</li>
 <li>Begalle, R. L., DiStefano, L. J., Blackburn, T. and Padua, D. A. (2012) Quadriceps and hamstrings coactivation during common therapeutic exercises. Journal of Athletic Training, 47(4), 396-405</li>
</ol>

Bibliography

© 2019 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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