Introduction

Anatomical Factors Affecting Joint Stiffness

Practitioner Factors

Technique Factors

Analgesia

H-Reflex, M-Wave, and V-Wave Response

Central Nervous System Mediated Changes

Sympatho-Excitatory Effects

Muscle Activity: Spine

Muscle Activity: Extremities

Additional Considerations

Research Summary

Myth Busting

Kinematics: Cervical Spine

Kinematics: Lumbar Spine

Kinematics: Shoulder

Kinematics: Adjacent Segments

Effects on Structures

Mechanical Factors Affecting Joint Stiffness

Effects of Joint Mobilizations and Manipulations

AOTA

AUSPHYSIO

NCBTMB

TPTA

NYPT

PACE

<p><span>Physical rehabilitation professionals, including physical therapists, osteopaths, and chiropractors, have been refining joint mobilizations and joint manipulations for 100s of years. There are even depictions of joint mobilization treatment that are 1000s of years old. Joint mobilization strategies have been published for chronic pain of the low back, hand pain, extremity joint issues, and various sports injuries. Some practitioners have noted the effect of joint mobilizations and joint manipulations on <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity and have <a id="integration" data-tip="1473" target="_blank" href="/glossary-term/integration" class="glossary">integrated</a> these techniques into routines for <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> weakness, <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> strains, and recurring pain relief for active <a id="trigger-point" data-tip="1634" target="_blank" href="/glossary-term/trigger-point" class="glossary">trigger points</a>.&#xA0;</span></p>
<p><span>The neurophysiological and mechanical effects of mobilizations and manipulations are actually quite complex. However, the simplest and most effective recommendation for their use is the intent to reduce joint stiffness for <a id="specificity" data-tip="1224" target="_blank" href="/glossary-term/specificity" class="glossary">specific</a> joints that have been assessed as exhibiting a reduction in <a id="arthrokinematics" data-tip="1861" target="_blank" href="/glossary-term/arthrokinematics" class="glossary">joint play</a> (<a id="arthrokinematics" data-tip="1701" target="_blank" href="/glossary-term/arthrokinematics" class="glossary">arthrokinematic motion</a>). Despite outcome studies demonstrating the efficacy of this approach to using these techniques, it would be presumptive to imply that there is a single, or a simple reason, that these techniques are effective. Some studies even imply mechanisms that are similar to deep tissue massage, massage guns, and other <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> tissue and <a id="connective-tissue-cell" data-tip="1368" target="_blank" href="/glossary-term/connective-tissue-cell" class="glossary">connective tissue</a> techniques, that are related to <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> endings involved in neuromuscular reflexes like autogenic inhibition (relaxation response), and altered cortisol concentrations (stress <a id="hormone" data-tip="1266" target="_blank" href="/glossary-term/hormone" class="glossary">hormone</a>), and central <a id="nervous-system" data-tip="1690" target="_blank" href="/glossary-term/nervous-system" class="glossary">nervous system</a> mediated pain relief which may be particularly effective for the treatment of chronic pain.&#xA0;<br></span></p>
<p><span>We hope this course helps to build a foundation of knowledge regarding the effects of joint intended technique from a very large body of research and rich clinical history. Further, this course is pre-approved for credits toward the <a id="integration" data-tip="1473" target="_blank" href="/glossary-term/integration" class="glossary">Integrated</a> Manual Therapist (IMT) Certification, and pre-approved for continuing education credits for sports medicine professionals and health care providers (physical therapists, athletic trainers, massage therapists, chiropractors, occupational therapists, etc.).<br></span></p>
<h3>Brookbush Institute&apos;s Position Statement</h3>
<p>Mobilizations and manipulations result in kinematic, neurophysiological, and muscular changes that have been correlated with the improvement of various subjective and objective patient outcomes, both short-term and long-term. Further, these changes have been demonstrated in randomized placebo/nocebo-controlled trials, implying the effects are not attributable to placebo or patient perceptions/expectations.</p>
<h3><span>What this Course Covers</span></h3>
<ul>
  <li><span>Myth Busting</span>
    <ul>
      <li><span>The Effects Are Not Placebo</span></li>
    </ul>
  </li>
  <li>Kinematics
    <ul>
      <li>Joint Motion During Mobilization and Manipulation</li>
      <li>Factors affecting force during mobilization and manipulations.</li>
      <li>Factors Affecting Joint Stiffness</li>
      <li>Effect on Structures</li>
    </ul>
  </li>
  <li><a id="nervous-system" data-tip="1690" target="_blank" href="/glossary-term/nervous-system" class="glossary">Nervous System</a>
    <ul>
      <li>H-reflex, M-wave, and V-wave Response</li>
      <li>Central <a id="nervous-system" data-tip="1690" target="_blank" href="/glossary-term/nervous-system" class="glossary">Nervous System</a> (CNS) Mediated Changes</li>
      <li>Sympatho-excitatory Effects</li>
      <li>Analgesia</li>
    </ul>
  </li>
  <li><a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">Muscle</a> Activity
    <ul>
      <li>Spine</li>
      <li>Extremities</li>
      <li>Additional Considerations</li>
    </ul>
  </li>
</ul>
<h3><span>Related Courses</span></h3>
<ul>
  <li><a href="https://brookbushinstitute.com/courses/introduction-joint-mobilizations-joint-manipulations" target="_blank" rel="noopener">Joint Mobilization and Manipulation: Introduction</a></li>
  <li><a href="https://brookbushinstitute.com/article/mobilization-and-manipulation-reliability-of-palpation-and-assessment" target="_blank" rel="noopener" style="letter-spacing: 0px;">Joint Stiffness </a><a id="assessment" data-tip="1478" target="_blank" href="/glossary-term/assessment" class="glossary">Assessment</a> by Palpation</li>
  <li><span style="background-color: transparent; font-family: inherit; font-size: inherit; font-style: inherit; font-variant-ligatures: inherit; font-variant-caps: inherit; font-weight: inherit; letter-spacing: 0px;"></span><a href="https://brookbushinstitute.com/course/joint-mobilization-and-manipulation-risk-of-adverse-events" style="letter-spacing: 0px;">Joint Mobilizations and Manipulations: Risk of Adverse Events</a></li>
  <li><a href="https://brookbushinstitute.com/courses/joint-mobilizations-and-manipulations-evidence-based-teaching-and-learning" title="Joint Mobilization and Manipulation: Evidence-based Teaching and Learning" target="_blank" rel="noopener">Joint Mobilizations and Manipulations: Evidenced-based Teaching and Learning</a></li>
</ul>

Course Description: Effects of Joint Mobilizations and Manipulations

Effects of Joint Mobilizations and Manipulations Webinar

<h3>Position Statement</h3>
<p>Mobilizations and manipulations result in kinematic, neurophysiological, and muscular changes that have been correlated with the improvement of various subjective and objective patient outcomes, both short-term and long-term. Further, these changes have been demonstrated in randomized placebo/nocebo controlled trials, implying the effects are not attributable to placebo or patient perceptions/expectations.</p>
<h3>Narrative Quick Summary</h3>
<h4><strong>Kinematics:</strong></h4>
<p>Mobilizations and manipulations are likely to impart more <a id="arthrokinematics" data-tip="1701" target="_blank" href="/glossary-term/arthrokinematics" class="glossary">arthrokinematic motion</a>, but less <a id="osteokinematic-motion" data-tip="1518" target="_blank" href="/glossary-term/osteokinematic-motion" class="glossary">osteokinematic motion</a>, than an individual&apos;s active range of motion. The stiffness curve expressed during joint mobilizations and manipulations includes an initial non-linear toe, a peak representing <a id="arthrokinematics" data-tip="1863" target="_blank" href="/glossary-term/arthrokinematics" class="glossary">arthrokinematic</a> end range and/or application of peak force, and a tail that coincides with decreased stiffness during the duration of the technique as a result of viscoelastic creep. Neither mobilizations nor manipulations are likely to result in enough force to significantly increase the risk of tissue damage, and although manipulations impart more initial force, the total force is similar to mobilizations. Various factors may alter the force imparted by the clinician including intent, experience, and the amount of plinth padding; however, many variables, like gender and technique, have less influence than is commonly assumed. Improvements in patient outcomes following mobilizations and manipulations are correlated with increased range of motion (ROM), decreased joint stiffness, changes in <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity, increased <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> root space, and increased joint space, but are not correlated with an immediate decrease in damage to tissues, including intervertebral discs.</p>
<h4><strong>Nervous System:</strong></h4>
<p>Mobilizations and manipulations may result in local and <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> analgesia via attenuation of <a id="dorsal" data-tip="1554" target="_blank" href="/glossary-term/dorsal" class="glossary">dorsal</a> horn neurons and C-fiber innervated afferents <a id="proximal" data-tip="1564" target="_blank" href="/glossary-term/proximal" class="glossary">proximal</a> to the intended segment, a segment above or below the intended segment, and potentially more <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> sites of the ipsilaterally innervated extremity. Further, manipulation (more than mobilization) may result in a transient decrease in H-reflex <a id="sensitivity" data-tip="1226" target="_blank" href="/glossary-term/sensitivity" class="glossary">sensitivity</a> and amplitude, and/or normalization of H-reflex latency in individuals exhibiting dysfunction. Sympatho-excitatory effects have been demonstrated in multiple studies, including changes in skin conductance, skin temperature, heart rate, respiratory rate, blood pressure, and pupil dilation. And, Central <a id="nervous-system" data-tip="1690" target="_blank" href="/glossary-term/nervous-system" class="glossary">nervous system</a> changes have been demonstrated including a reduction in the activity of the pain centers of the brain (especially the insular cortex), increased maximal motor-evoked potentials as demonstrated by transcranial magnetic stimulation, and alterations in <a id="hormone" data-tip="1266" target="_blank" href="/glossary-term/hormone" class="glossary">hormone</a> and neurotransmitter levels. In summary, studies have demonstrated that mobilizations and manipulations have a significant effect on sensory afferents, the peripheral <a id="nervous-system" data-tip="1690" target="_blank" href="/glossary-term/nervous-system" class="glossary">nervous system</a>, central <a id="nervous-system" data-tip="1690" target="_blank" href="/glossary-term/nervous-system" class="glossary">nervous system</a>, autonomic <a id="nervous-system" data-tip="1690" target="_blank" href="/glossary-term/nervous-system" class="glossary">nervous system</a>, and hormone/neurotransmitter levels.</p>
<h4><strong>Muscle Activity:</strong></h4>
<p>Mobilization and manipulations, performed alone or <a id="integration" data-tip="1473" target="_blank" href="/glossary-term/integration" class="glossary">integrated</a> into a rehabilitation program, can have a significant effect on <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity, thickness, and strength, and these changes may be correlated with improvements in patient outcomes, both short-term and long-term. Similar to the analgesic effects described above, the muscles most affected are those with attachment-to or crossing the intended segment; further, muscles may be affected from the segment above or below, or more <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> along the ipsilaterally innervated extremity. W<span style="color: #000000;">hen considered relative to the altered EMG activity in those exhibiting dysfunction, the changes noted following mobilizations and manipulations imply that activity is &quot;normalized&quot; (over-active muscles exhibit a reduction in activity, under-active muscles exhibit an increase in activity). During mobilizations and manipulations, symptomatic individuals may exhibit larger changes in joint stiffness, but exhibit latent or inhibited reflexive increases in <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity. Thoracic mobilizations and manipulations may have an effect on maximal respiratory values, but will only improve resting respiratory values for individuals with compromised pulmonary function. Last </span>mobilizations and manipulations may only improve proprioception and <a id="balance" data-tip="1190" target="_blank" href="/glossary-term/balance" class="glossary">balance</a> when added to a long-term (4 weeks or more) <a id="integration" data-tip="1473" target="_blank" href="/glossary-term/integration" class="glossary">integrated</a> program that includes exercise. In summary, mobilizations and manipulations may normalize <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity, and increase <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> thickness, strength, and/or endurance, and these changes may have a positive effect on short-term and long-term outcomes, especially when added to an <a id="integration" data-tip="1473" target="_blank" href="/glossary-term/integration" class="glossary">integrated</a> exercise program.</p>
<h2>Relevant Definitions</h2>
<ul>
  <li><strong>A-fiber mediated receptors:</strong>&#xA0;Golgi tendon organ, <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> spindle, touch, and some forms of pain</li>
  <li><strong>C-fiber mediated receptors:</strong> thermal pain <a id="sensitivity" data-tip="1226" target="_blank" href="/glossary-term/sensitivity" class="glossary">sensitivity</a>, cutaneous pain (pin-prick) tolerance, and pain pressure threshold</li>
  <li><strong>Algesia:</strong> <a id="sensitivity" data-tip="1226" target="_blank" href="/glossary-term/sensitivity" class="glossary">sensitivity</a> to pain</li>
  <li><strong>Hypoalgesic:</strong> decreased <a id="sensitivity" data-tip="1226" target="_blank" href="/glossary-term/sensitivity" class="glossary">sensitivity</a> to pain</li>
  <li><strong>Hyperalgesic:</strong> increased <a id="sensitivity" data-tip="1226" target="_blank" href="/glossary-term/sensitivity" class="glossary">sensitivity</a> to pain</li>
  <li><strong>Analgesic:</strong> an agent that diminishes the sensation of pain without loss of consciousness</li>
  <li><strong>H-reflex (Hoffmann&apos;s Reflex):</strong> A reflexive reaction of muscles to an electrically induced stimulation of sensory fibers (Ia <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> spindle afferents), that may be considered a &quot;lab version&quot; of the stretch (monosynaptic) reflex. H-reflex replaces stretch reflex in research because inputs and outcomes can be better controlled, resulting in higher <a id="sensitivity" data-tip="1226" target="_blank" href="/glossary-term/sensitivity" class="glossary">sensitivity</a> and <a id="reliability" data-tip="1515" target="_blank" href="/glossary-term/reliability" class="glossary">reliability</a>.</li>
  <li><strong>M-wave:</strong> Muscle-wave, t<span class="hvr">he</span>&#xA0;<span class="hvr">tracing</span>&#xA0;of&#xA0;<span class="hvr">the</span>&#xA0;<span class="hvr">earliest</span>&#xA0;electromyography&#xA0;(EMG)&#xA0;<span class="hvr">response</span>&#xA0;to&#xA0;<span class="hvr">the</span>&#xA0;<span class="hvr">stimulation</span>&#xA0;of&#xA0;a&#xA0;<span class="hvr">motor</span>&#xA0;<span class="hvr">nerve,</span>&#xA0;generally recorded during H-reflex testing.</li>
  <li><strong>V-wave:</strong>&#xA0;Volitional wave, is a measure of maximum voluntary evoked potential recorded using electromyography (EMG).</li>
  <li><strong>Transcranial Magnetic Stimulation (TMS):</strong>&#xA0;TMS is a non-invasive <a id="posture" data-tip="1660" target="_blank" href="/glossary-term/posture" class="glossary">form</a> of brain stimulation using a magnetic field to induce an electric current within <a id="specificity" data-tip="1224" target="_blank" href="/glossary-term/specificity" class="glossary">specific</a> areas of the brain.&#xA0;TMS can be used to measure the activity and function of <a id="specificity" data-tip="1224" target="_blank" href="/glossary-term/specificity" class="glossary">specific</a> brain circuits, most commonly with single or paired magnetic pulses.</li>
  <li><strong>Sympatho-excitatory Effects:</strong> In research, changes in sympathetic <a id="nervous-system" data-tip="1690" target="_blank" href="/glossary-term/nervous-system" class="glossary">nervous system</a> activity are assessed using indirect measures including changes in skin conductance (an indicator of sweat gland activity), skin temperature, blood pressure, and heart rate variability, and less commonly used are changes in respiratory rate and pupil diameter.</li>
</ul>

<p>A new myth has been trending suggesting the effects of joint manipulations and mobilizations are nothing more than placebo. This myth likely started from an assumption that studies investigating some of the transient neurophysiological effects following mobilizations and manipulations were representative of all the effects, including the false presumption that decreases in pain were transient. This myth has gained momentum despite the publication of dozens, and possibly hundreds, of peer-reviewed randomized placebo-controlled trials (RCTs), which is the study design developed to account for placebo effects. Many of these RCTs are discussed in this review; however, this section covers a few selected studies with methodological designs that account for additional confounding variables that further decrease the likelihood of the effects of manipulations and mobilizations being attributable to placebo.&#xA0;&#xA0;</p>
<h4><strong>The Effects of Stress</strong></h4>
<p>Two studies investigating the effects of mobilizations and manipulations recorded patient stress, a potential contributor to nocebo effects. Vicenzino et al. demonstrated that cervical <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> <a id="glide" data-tip="1598" target="_blank" href="/glossary-term/glide" class="glossary">glide</a> mobilizations performed on asymptomatic individuals resulted in sympathoexcitatory effects, and there was no correlation between the magnitude of effects and the level of stress or pain reported by the participant. This includes similar sympathoexcitatory effects from session to session, despite stress decreasing from session to session (187). An RCT by Alonso-Perez compared cervical manipulations, cervical mobilizations, and cervical <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> <a id="glide" data-tip="1598" target="_blank" href="/glossary-term/glide" class="glossary">glide</a> mobilizations, demonstrating that all techniques decreased pain pressure <a id="sensitivity" data-tip="1226" target="_blank" href="/glossary-term/sensitivity" class="glossary">sensitivity</a> at the cervical spine and elbow, mobilizations resulted in larger decreases in pain pressure <a id="sensitivity" data-tip="1226" target="_blank" href="/glossary-term/sensitivity" class="glossary">sensitivity</a> than manipulation, and catastrophizing by the patient only significantly reduced the effectiveness of manipulations when the levels of stress were high (no significant effects were demonstrated for low and moderate levels) (186). These studies demonstrate that patient stress is unlikely to have an effect on sympathoexcitatory or analgesic effects, with the exception of attempting high-velocity manipulations on patients who exhibit a high level of stress.</p>
<h4><strong>Effect of Patient Education and Messaging (Nocebo Control Trials)</strong></h4>
<p>Recent studies investigating the effects of patient education and messaging on outcomes following mobilizations and manipulations add nocebo groups to several placebo-control RCTs. An RCT by Bialosky et al. demonstrated that messaging designed to result in negative expectations preceding lumbar manipulation had no effect on local and <a id="ipsilateral" data-tip="1550" target="_blank" href="/glossary-term/ipsilateral" class="glossary">ipsilateral</a> lower extremity C-fiber mediated cutaneous hypoalgesia; however, the messaging did have an effect on subjective reports of lumbar pain following treatment (99). Riley et al. demonstrated that education regarding the positive effects of manipulations received prior to treatment of shoulder pain with a combination of thoracic manipulation and home exercise, significantly improved the patient&apos;s perception of treatment; however, improvements in pain and disability were similar for groups that did not receive education (257). An RCT by Niemist&#xF6; et al. demonstrated that the treatment of chronic low back pain with mobilizations and stabilization exercise resulted in larger improvements in pain and disability than a combination of physician advice and an education booklet during 5- and 12-month follow-ups (258). Another RCT by Niemisto et al. with 1-year follow-up demonstrated major recovery of 60% of patients receiving a combination of mobilizations, exercise, and physician consultation/education, compared to 51% of patients in a group that received similar treatment without mobilizations. Despite this study demonstrating psychosocial issues having a strong correlation with failure to recover, the study clearly demonstrates that the addition of mobilizations resulted in significantly better outcomes (259). In summary, these studies demonstrate that messaging, education, and expectations may have an impact on immediate measures of subjective pain and patient satisfaction scores, but is unlikely to have any effect on objective measures or long-term patient outcomes. Further, adding mobilization and manipulation techniques to an <a id="integration" data-tip="1473" target="_blank" href="/glossary-term/integration" class="glossary">integrated</a> intervention including education is likely to result in further improvements in patient outcomes.</p>
<table border="1" height="255" style="border-collapse: collapse;">
  <tbody>
    <tr>
      <td>
        <h4><strong>Does the type of education matter:</strong></h4>
        <p>An experimental study by Lluch et al. investigated treatment for knee osteoarthritis, comparing knee joint mobilization and pain science education to knee joint mobilization and biomedical education. The findings demonstrated no difference between the groups for pain and disability scores; however, the pain science group demonstrated <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> results for psychosocial variables related to pain catastrophizing and kinesiophobia (260). Obviously, these outcomes suggest pain science education may be <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> to biomedical education; however, the improvements correlated with the addition of pain science education are likely separate from, and have no influence on, the objectively measured effects following mobilizations and manipulations.</p>
      </td>
    </tr>
  </tbody>
</table>
<h4><strong>Randomized Placebo-Controlled (and More) Trials</strong></h4>
<p>Several studies include placebo-control groups, as well as additional experimentation that may account for confounding variables that could be attributed to placebo-like effects. An RCT by George et al. demonstrated that lumbar manipulation performed on asymptomatic individuals altered C-fiber afferent activity but not A-fiber afferent activity. Further, this study also compared the experimental group to a cycling group to demonstrate that the hypoalgesia was not correlated with physiological changes (98). A similar RCT by Bialosky et al. demonstrated that lumbar manipulation had a significant effect on temporal summation of thermal pain (c-fiber mediated afferents). Additionally, the experimental group was compared to groups performing stationary cycling and lumbar extension exercise, and neither group exhibited the same alterations (110). These studies clearly demonstrate altered c-fiber mediated analgesia when compared to placebo control, and further account for the confounding variables of motion, exercise, and changes in physiology associated with cardiovascular exercise. It may also be worth noting that there is no record of placebo resulting in selective alteration of C-fiber mediated afferents, without an effect on A-fiber mediated afferents.&#xA0;</p>
<p>Additional studies demonstrate that mobilizations and manipulations have a significant effect on H-reflex (stretch reflex), and several of these studies account for additional confounding variables. <span style="background-color: transparent; font-family: inherit; font-size: inherit; font-style: inherit; font-variant-ligatures: inherit; font-variant-caps: inherit; font-weight: inherit; letter-spacing: 0px;">Dishman et al. demonstrated that lumbar manipulation had a larger effect on the attenuation of </span><a href="https://brookbushinstitute.com/article/gastrocnemius-plantaris" style="letter-spacing: 0px;">gastrocnemius</a><span style="background-color: transparent; font-family: inherit; font-size: inherit; font-style: inherit; font-variant-ligatures: inherit; font-variant-caps: inherit; font-weight: inherit; letter-spacing: 0px;"> H-reflex than the side-lying loaded position used during set-up (117). And, a more recent RCT by Dishman et al. demonstrated similar findings, noting high-velocity lumbar rotation manipulation resulted in significant attenuation of H-reflex compared to side-positioning and loaded side-positioning, and further that the attenuation was similar for both symptomatic and asymptomatic individuals (118). An RCT by Murphy et al. demonstrated that sacroiliac joint manipulation resulted in a significant attenuation of H-reflex of the <a id="ipsilateral" data-tip="1550" target="_blank" href="/glossary-term/ipsilateral" class="glossary">ipsilateral</a> leg, had no effect on the H-reflex of the <a id="contralateral" data-tip="1549" target="_blank" href="/glossary-term/contralateral" class="glossary">contralateral</a> leg, and sham intervention had no effect on either leg. Further, the study was repeated with anesthetic cream over the SIJ to determine if the decrease in H-reflex was related to cutaneous afferent stimulation, and the findings were similar, suggesting that H-reflex attenuation was not the result of cutaneous input (120). In summary, the H-reflex attenuation following lumbosacral manipulation is significantly larger than placebo, and cannot be attributed to patient positioning, loaded patient positioning, or cutaneous input. Further, there is no evidence that a placebo could result in <a id="unilateral" data-tip="1551" target="_blank" href="/glossary-term/unilateral" class="glossary">unilateral</a> changes in reflex activity.</span></p>
<p><span style="background-color: transparent; font-family: inherit; font-size: inherit; font-style: inherit; font-variant-ligatures: inherit; font-variant-caps: inherit; font-weight: inherit; letter-spacing: 0px;">Finally, an RCT by Kamel et al. demonstrated that postpartum females with low back pain receiving lumbar mobilizations, infrared and ultrasound, 3 sessions/week for 4 weeks, exhibited a larger reduction in pain, increase in function, and reduction in </span><a href="https://brookbushinstitute.com/article/erector-spinae" style="letter-spacing: 0px;">erector spinae</a><span style="background-color: transparent; font-family: inherit; font-size: inherit; font-style: inherit; font-variant-ligatures: inherit; font-variant-caps: inherit; font-weight: inherit; letter-spacing: 0px;"> resting EMG activity when compared to infrared and ultrasound alone or in combination with &quot;placebo mobilization&quot; (237). This study clearly demonstrates that lumbar mobilization is more effective than placebo, even when mobilization is added to an <a id="integration" data-tip="1473" target="_blank" href="/glossary-term/integration" class="glossary">integrated</a> intervention plan.&#xA0;</span></p>

Myth Busting: The Effects are Not Placebo

Kinematics: Joint Motion During Mobilizations and Manipulations

<h4><strong>Cervical Manipulation</strong></h4>
<p>Several studies have analyzed joint motion during cervical manipulation.&#xA0;Anderst et al. demonstrated that during cervical manipulation there was an increase in the gap between facet surfaces (facet gap) of 0.9mm &#xB1; 0.40mm, with a mean facet gap rate of 6.2 &#xB1; 3.9 mm/s, mean peak force of 65 &#xB1; 4 N, and rate of total force applied of 440 &#xB1; 58 N/s. Additionally, pain scores, facet gap, segment ROM, and gross cervical ROM improved following manipulation (1). An initial study by Dugailly et al. investigated the motion of the upper cervical spine during an upper cervical manipulation on 3 unembalmed cadaver specimens. The findings demonstrated that global cervical ROM of&#xA0;14 &#xB1; 5&#xB0; <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> flexion, 35 &#xB1; 7&#xB0; rotation, and 14 &#xB1; 8&#xB0; flexion-extension, and the ROM of C0&#x2013;C2 (regional ROM) was 10 &#xB1; 5&#xB0; <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> flexion, 30 &#xB1; 5&#xB0; rotation, and 16 &#xB1; 4&#xB0;&#xA0;flexion-extension (2). Additional studies by Dugailly et al. used more sophisticated modeling and demonstrated a mean ROM of 39&#xB0; with a standard deviation (SD) of 6&#xB0; for <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> flexion, 21&#xB0; (SD 7&#xB0;) rotation, and 8&#xB0; (SD 5&#xB0;) flexion/extension. During the impulse period the mean magnitude was 8&#xB0; (SD 2&#xB0;) <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> flexion, 5&#xB0; (SD, 2&#xB0;) <a id="axial-skeleton" data-tip="1292" target="_blank" href="/glossary-term/axial-skeleton" class="glossary">axial</a> rotation, and 3&#xB0; (SD, 2&#xB0;) flexion/extension. Mean impulse velocity was 139&#xB0;/s (SD 39&#xB0;/s), <a id="axial-skeleton" data-tip="1292" target="_blank" href="/glossary-term/axial-skeleton" class="glossary">axial</a> rotation/lateral flexion ratios were an average of 0.6 (SD, 0.3), and the helical axis was primarily oblique and located on the same side as the impulse (3-5). Williams et al. compared the upslope and downslope manipulation techniques performed by two different practitioners on 13 asymptomatic subjects.&#xA0;The downslope manipulation started with a mean pre-manipulative position of 24.8&#xB0; side bending and 2.7&#xB0; rotation, thrust displacement magnitude of 4.5&#xB0; side bending and 5.4&#xB0; rotation, with a mean thrust velocity of 57.5&#xB0;/s side bending and 74.8&#xB0;/s rotation. The upslope pre-manipulative position started with a mean of 30.1&#xB0; side bending and 8.4&#xB0; rotation, with a mean thrust displacement magnitude of 4.5&#xB0; side bending and 12.7&#xB0; rotation, and a mean thrust velocity of 75.9&#xB0;/s side bending and 194.7&#xB0;/s rotation. Although the upslope technique started with a larger deviation from neutral ROM, greater amplitude, and greater velocity, it must be considered that the two techniques were performed by two different practitioners (6). In summary, these studies demonstrate that&#xA0;cervical manipulations are comprised of <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> flexion, rotation, and flexion/extension. The pre-manipulative ROM for each joint action is relatively small, with the highest values reported being 25&#xB0; of <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> flexion or 35&#xB0; of rotation (one joint action being dominant, and the other being 10&#xB0; or less), in addition to 10&#xB0; or less of flexion/extension. Regional (segmental) ROM&#xA0;for <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> flexion and rotation is less than half of total ROM. Further, the velocity of cervical manipulations may be relatively high (up to 194.7&#xB0;/s); however, the magnitude is relatively small, including 0.9cm &#xB1; 0.40 facet gap, 8&#xB0; (SD 2&#xB0;) <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> flexion, 5&#xB0; (SD 2&#xB0;) <a id="axial-skeleton" data-tip="1292" target="_blank" href="/glossary-term/axial-skeleton" class="glossary">axial</a> rotation, and 3&#xB0; (SD 2&#xB0;) flexion/extension.</p>
<h4><b>Cervical Manipulations Use Less ROM than Available&#xA0;Active ROM</b></h4>
<p>Several studies have demonstrated that the ROM used during cervical manipulation is less than the participant&apos;s active ROM. Van Geyt et al. demonstrated that cervical manipulation magnitude did not exceed active ROM; further, cavitation occurrence was correlated with frontal plane ROM, sagittal acceleration,&#xA0;total velocity, and practitioner experience (7). Liguo et al. used motion capture technology to demonstrate that the cervical ROM during cervical rotation-traction manipulation was less than the patient&apos;s active cervical ROM, head rotation angles were similar during pre-manipulation and thrust positions, and thrust direction was primarily vertical (8). Klein et al. used 3D&#xA0;electrogoniometry to demonstrate that the ROM achieved during cervical manipulations by one experienced practitioner on 14 asymptomatic subjects was significantly less than participants&apos; active ROM and were not significantly affected by the side or segment level manipulated. Mean ROM for manipulations was&#xA0;30&#xB0; <a id="axial-skeleton" data-tip="1292" target="_blank" href="/glossary-term/axial-skeleton" class="glossary">axial</a> rotation, 46&#xB0; <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> bending, and 2&#xB0; flexion (9). Salem et al. used a CT scan to investigate the cervical pre-manipulative position, demonstrating that the head and neck were rotated to the left and laterally flexed to the right, while the lower cervical spine exhibited rotation to the right. Again, segmental rotation ROM in the pre-manipulative position was less than the participant&apos;s active ROM (10). These studies note similar kinematic to the studies in the previous section; however, they include comparative data to demonstrate that pre-manipulative and thrust ROM is less than the participant&apos;s active ROM. These findings may have implications regarding the safety of cervical manipulations; which is discussed in further detail later in this review.</p>
<h4><strong>Cervical Mobilization</strong></h4>
<p>A few studies have been published investigating the kinematics of cervical mobilizations. Lee et al. demonstrated that PA cervical mobilization resulted in an increase in the cervical lordosis, including the extension of upper cervical segments and flexion of the lower cervical segments, and lordosis increased with repeated oscillations (11).&#xA0;An interesting study by McGregor et al. used MRI to demonstrate that central PA mobilizations of the cervical spine resulted in more soft tissue deformation than cervical body motion; however, PA mobilizations produced an extension of the upper segments, flexion of the lower segments, either flexion or extension of the middle segments, and an overall increase in the cervical lordosis with repeated loading (12-13). The motion described in these studies implies&#xA0;the kinematics of mobilization are less complex than manipulation, with PA cervical mobilizations resulting in significant soft tissue deformation and vertebral motion that is likely to increase the cervical lordosis. The motion of increased cervical lordosis includes <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> displacement of the target segment, upper cervical extension, lower cervical flexion, and either flexion or extension of middle segments.</p>

Cervical Spine

<p>Studies have investigated joint motion during both lumbar mobilizations and lumbar manipulations. Howarth et al. demonstrated that during a side-lying rotational lumbar manipulation, the spine underwent <a id="ipsilateral" data-tip="1550" target="_blank" href="/glossary-term/ipsilateral" class="glossary">ipsilateral</a> rotation, <a id="contralateral" data-tip="1549" target="_blank" href="/glossary-term/contralateral" class="glossary">contralateral</a> flexion, and extension. Participants experienced an <a id="ipsilateral" data-tip="1550" target="_blank" href="/glossary-term/ipsilateral" class="glossary">ipsilateral</a> <a id="axial-skeleton" data-tip="1292" target="_blank" href="/glossary-term/axial-skeleton" class="glossary">axial</a> rotation moment of a mean 37 Nm followed by a <a id="contralateral" data-tip="1549" target="_blank" href="/glossary-term/contralateral" class="glossary">contralateral</a> moment of &#x2212; 45.8 Nm (14). Research on vertebral motions during lumbar mobilization describes simpler kinematics than those described for lumbar manipulation. Lee et al. demonstrated that during simulated oscillatory central PA lumbar mobilizations it was the lower (<a id="caudal" data-tip="1557" target="_blank" href="/glossary-term/caudal" class="glossary">caudal</a>) segment that moved more, and that stiffness changes could be described by viscoelastic creep (15). Kulig et al. used MRI to demonstrate that central PA mobilizations of a lumbar segment resulted in <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> motion and extension of the target segment (16). Tsung et al. demonstrated that <a id="unilateral" data-tip="1551" target="_blank" href="/glossary-term/unilateral" class="glossary">unilateral</a> <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> to <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> (UPA) mobilization of the lumbar spine resulted in flexion, <a id="contralateral" data-tip="1549" target="_blank" href="/glossary-term/contralateral" class="glossary">contralateral</a> flexion, and <a id="contralateral" data-tip="1549" target="_blank" href="/glossary-term/contralateral" class="glossary">contralateral</a> rotation of the segment being mobilized (multi-planer) (17). Lee et al. demonstrated that lumbar mobilization force of 150N applied to the spinous process (central PA) resulted in the extension of lumbar segments, except for L5 which flexed on the sacrum (18). Keller et al. demonstrated that during a simulated 100N PA mobilization to L3 that segmental impulsive displacement was 2.4mm, and oscillatory displacement was 8.23mm with an&#xA0;axial component of 0.41 mm, and flexion/extension rotation component of 1.49&#xB0;. Lumbar PA motion was relatively insensitive to thrust angle and offset; however, flexion/extension rotation increased significantly (2x&apos;s +) when thrust angle was adjusted from vertical to&#xA0;&#x2212;5&#xB0; (<a id="caudal" data-tip="1557" target="_blank" href="/glossary-term/caudal" class="glossary">caudal</a>) (19). In summary, these studies demonstrate that&#xA0;lumbar manipulation is comprised of a combination of&#xA0;ipsilateral rotation, <a id="contralateral" data-tip="1549" target="_blank" href="/glossary-term/contralateral" class="glossary">contralateral</a> flexion, and extension. Lumbar mobilizations result primarily in <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> displacement with some flexion or extension depending on the segment. During mobilization, <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> displacement is relatively insensitive to PA force angle; however, segmental flexion/extension increased significantly (2x&apos;s +) when PA force angle was adjusted by as little as 5&#xB0;. Further, <a id="unilateral" data-tip="1551" target="_blank" href="/glossary-term/unilateral" class="glossary">unilateral</a> PA mobilizations result in some additional <a id="contralateral" data-tip="1549" target="_blank" href="/glossary-term/contralateral" class="glossary">contralateral</a> rotation and <a id="contralateral" data-tip="1549" target="_blank" href="/glossary-term/contralateral" class="glossary">contralateral</a> flexion.</p>
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        <h4><strong>Spine Manipulation, Kinematics, and Outcomes:</strong></h4>
        <p>Two studies have correlated altered kinematics following manipulation with improvements in patient outcomes. As mentioned above,&#xA0;Anderst et al. demonstrated that during cervical manipulation there was an increase in the gap between facet surfaces (facet gap) and that following manipulation, resting facet gap, segment ROM, gross cervical ROM, and pain scores improved (1). Additionally, an RCT by Feng et al. compared 46 patients receiving hot packs and bed rest, to 48 patients receiving hot packs, bed rest, and Feng&apos;s lumbar manipulation. The findings demonstrated that following 3 weeks of therapy the manipulation group had better scores on pain and functional outcome measures, and MRI myelography demonstrated larger <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> root space. However, neither group exhibited changes in the sagittal diameter index of the herniated nucleus pulposus or the angle between the <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> root sleeve and the thecal sac (20). These studies may suggest that manipulations are effective, at least in part, due to increased ROM, <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> root space, and facet gap, but not necessarily morphological changes of the disk.</p>
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<h3></h3>

Lumbar Spine

<p>Research on shoulder mobilizations describes increased <a id="arthrokinematics" data-tip="1701" target="_blank" href="/glossary-term/arthrokinematics" class="glossary">arthrokinematic motion</a> when mobilizations were added to&#xA0;osteokinematic joint motions. A study using fresh cadaver specimens by Ho et al. compared glenohumeral <a id="arthrokinematics" data-tip="1701" target="_blank" href="/glossary-term/arthrokinematics" class="glossary">arthrokinematic motion</a> to&#xA0;52&#xB0; of shoulder abduction during both passive abduction and a mobilization with movement (WMW) technique. During passive abduction glenohumeral motion was less than 0.9 mm in the <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a>, <a id="inferior" data-tip="1569" target="_blank" href="/glossary-term/inferior" class="glossary">inferior</a>, and <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> directions, and during the MWM technique the mean displacement was 7.7mm&#xA0;posterior, 2.7 mm <a id="inferior" data-tip="1569" target="_blank" href="/glossary-term/inferior" class="glossary">inferior</a>, and&#xA0;0.5 mm <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> (20). Henderson et al. used ultrasound to determine correlations between glenohumeral <a id="arthrokinematics" data-tip="1701" target="_blank" href="/glossary-term/arthrokinematics" class="glossary">arthrokinematic motion</a> and shoulder mobilization performed on asymptomatic individuals. <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> forces of 125&#x2009;+/&#x2212;&#x2009;50&#x2009;N resulted in 6.5&#x2009;+/&#x2212;&#x2009;4.0&#x2009;mm (mean approximate values) of <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> translation, and <a id="inferior" data-tip="1569" target="_blank" href="/glossary-term/inferior" class="glossary">inferior</a> forces of 80&#x2009;+/&#x2212;&#x2009;30&#x2009;N resulted in 5.5&#x2009;+/&#x2212;&#x2009;2.0&#x2009;mm of <a id="inferior" data-tip="1569" target="_blank" href="/glossary-term/inferior" class="glossary">inferior</a> translation. There was a significant correlation between <a id="inferior" data-tip="1569" target="_blank" href="/glossary-term/inferior" class="glossary">inferior</a> translation and <a id="inferior" data-tip="1569" target="_blank" href="/glossary-term/inferior" class="glossary">inferior</a> force; however, there was no significant correlation between <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> translation and posterolateral force (21). Talbott et al. investigated force, motion, and <a id="reliability" data-tip="1515" target="_blank" href="/glossary-term/reliability" class="glossary">reliability</a> during Kaltenborn <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> to <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> (AP) shoulder mobilization techniques demonstrating good inter-therapist <a id="reliability" data-tip="1515" target="_blank" href="/glossary-term/reliability" class="glossary">reliability</a>, significant differentiation of force between grades, and total motion of 3.0mm for grade I, 8.2mm for grade II, and 10.7mm for grade III (22). These studies demonstrate that&#xA0;mobilization&#xA0;is likely to result in 5 - 10mm of glenohumeral <a id="arthrokinematics" data-tip="1701" target="_blank" href="/glossary-term/arthrokinematics" class="glossary">arthrokinematic motion</a> in the direction of mobilization, which is approximately 5 - 10 times the amount of <a id="arthrokinematics" data-tip="1701" target="_blank" href="/glossary-term/arthrokinematics" class="glossary">arthrokinematic motion</a> noted during passive motion. Further, <a id="arthrokinematics" data-tip="1701" target="_blank" href="/glossary-term/arthrokinematics" class="glossary">arthrokinematic motion</a> is likely to increase with the amount of force used during mobilization from grades I - IV.</p>

Shoulder

<p>Several studies have compared the motion of the target and adjacent segments during mobilization and manipulation. Engel et al. demonstrated that during a <a id="prone" data-tip="1561" target="_blank" href="/glossary-term/prone" class="glossary">prone</a> cervicothoracic junction manipulation, significant rotation and extension occurred at all cervical segments (24). Gal et al. demonstrated that a thrust manipulation to T10 or T11 with reinforced hypothenar contact, performed on embalmed post rigor mortis human cadavers, resulted in significant displacement when compared to adjacent vertebrae and resulted in a return to a more extended position following manipulation (25-26). Lee et al. demonstrated that PA cervical mobilization to the 5th cervical vertebrae resulted in an increase in the cervical lordosis, including the extension of upper cervical segments and flexion of the lower cervical segments, and lordosis increased with repeated oscillations (11). These studies demonstrate that during mobilizations and manipulations the target segment likely moves the most; however, these techniques result in significant motion of adjacent segments. Another study by Lee et al. demonstrated that PA mobilizations resulted in significant motion of several segments above and below the targeted segment (based on the displacement of the skin); however, compared to quasi-static pressure, oscillatory mobilizations resulted in less displacement of adjacent segments (27). Additionally, a study mentioned above by Keller et al. demonstrated that during a simulated 100N PA mobilization to L3 that segmental impulsive displacement was 2.4mm, and oscillatory displacement was 8.23mm with an <a id="axial-skeleton" data-tip="1292" target="_blank" href="/glossary-term/axial-skeleton" class="glossary">axial</a> component of 0.41 mm, and a flexion/extension rotation component of 1.49&#xB0; (19). Another study by Lee et al. compared the stiffness of L3, L4, and L5, and also compared quasi-static to oscillatory forces, demonstrating that stiffness increased incrementally from L3 to L5 and oscillatory force resulted in greater stiffness than quasi-static forces (28). In summary, these studies imply that significant motion of adjacent segments occurs during mobilization and manipulation; however, the target segment is likely most affected. Additionally, studies suggest that the benefit of oscillations during mobilization, and/or the increased velocity during manipulation, maybe a relative decrease in accommodation by adjacent segments.</p>

Movement of Adjacent Segments

<h4><strong>Structures Affected:</strong></h4>
<p>Research has attempted to determine the structures most affected by forces imparted during joint mobilization and manipulation techniques.&#xA0;In a feasibility study by Maigne et al., a momentary increase in intradiscal pressure was recorded during a simulated lumbar thrust manipulation on 2 unembalmed cadaver specimens (29). Similarly, Tian et al. demonstrated that during lumbar manipulation the majority of the stress on the disk was on the annular fibers opposite the side of force application, with less stress imparted on the nucleus pulposus (30). Wang et al. demonstrated that during lumbar rotational mobilization, flexion increased disc displacement, and more disk displacement happened on the side opposite the direction of rotation (31). These studies suggest that&#xA0;manipulation imparts more stress on annular fibers than the nucleus pulposus, increasing flexion increases stress on <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> fibers, and rotation imparts more stress to the fibers on the posterior/contralateral side.</p>
<h4><strong>Stresses During Mobilization and Manipulation Techniques on Healthy and Degenerative Disks:&#xA0;</strong></h4>
<p>Additional studies consider force characteristics over the duration of the manipulation, and further, compare forces on healthy and degenerative disks. Xu et al. demonstrated that during simulated lumbar manipulation on a healthy disk that intradiscal pressure increased, displacement was greatest for the anterior/ipsilateral and posterior/contralateral sides of the disk, <a id="compression" data-tip="1595" target="_blank" href="/glossary-term/compression" class="glossary">compression</a> occurred on the anterior/ipsilateral side of the disk resulting in some <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> and <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> expansion of the <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> annulus, and more <a id="tension" data-tip="1229" target="_blank" href="/glossary-term/tension" class="glossary">tension</a> was created on the posterior/contralateral side of the disk (32). In a follow-up study, Xu et al. demonstrated that simulated manipulation on a lumbar disk exhibiting signs of degeneration resulted in similar intradiscal forces, and additional analysis demonstrated that the force increased over the duration of the manipulation in an arc from the anterior/ipsilateral to posterior/contralateral portions of the disk. Further, <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> root <a id="compression" data-tip="1595" target="_blank" href="/glossary-term/compression" class="glossary">compression</a> increased on the side opposite the direction of rotation (33). Chen et al. demonstrated that the force during fixed point seated lumbar rotation manipulation was directed at the disk on the posterior/contralateral side; and further, that degeneration of the disk reduced displacement and the amount of force to the intended segment (34). Another study by Li et al. investigated the amount of intradiscal pressure and maximum stress on the annulus during seated and side-lying lumbar rotation manipulation, demonstrating that displacement was most obvious in healthy disks; however, intradiscal pressure and annular stress was greater in disks exhibiting moderate degeneration (35). These studies demonstrate similar force characteristics as noted in the cadaver studies mentioned above. However, they add that&#xA0;force increases over the duration of the manipulation in an arc from the anterior/ipsilateral to posterior/contralateral portions of the disk, and distension of the disk may place additional stress on the <a id="contralateral" data-tip="1549" target="_blank" href="/glossary-term/contralateral" class="glossary">contralateral</a> <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> root. Further, force characteristics are similar for healthy disks and degenerative disks; however, distension is greater in healthy disks, intradiscal pressure may be greater in degenerative disks, and the amount of force imparted on each segment may be altered by the presence of healthy and degenerative disks.</p>
<h4><strong>Comparing Techniques:</strong></h4>
<p>Additional studies have compared the forces imparted on disks during various techniques. The study mentioned above by Li et al. demonstrated no significant difference in force characteristics between seated and side-lying lumbar manipulations.&#xA0;Another study by Xu et al. demonstrated that the lumbar oblique pulling manipulation (similar to the technique described in the BI video below), reduced intradiscal pressures when compared to rotational manipulations (36). As implied by the study by Wang et al. mentioned above (31), this may be due to the technique increasing extension rather than flexion during the thrust portion of the manipulation. In another study by Wang et al., lumbar mobilization and lumbar manipulation forces were simulated on 12 fresh cadaver specimens, demonstrating that disk forces were higher on the <a id="ipsilateral" data-tip="1550" target="_blank" href="/glossary-term/ipsilateral" class="glossary">ipsilateral</a> side during <a id="unilateral" data-tip="1551" target="_blank" href="/glossary-term/unilateral" class="glossary">unilateral</a> PA mobilizations, versus the <a id="contralateral" data-tip="1549" target="_blank" href="/glossary-term/contralateral" class="glossary">contralateral</a> side for manipulations. Further, the beginning and ending forces were similar, suggesting that only initial instant forces on disks may be higher during manipulations (37). These studies suggest that based on the forces imparted on disks, there are only subtle differences between various mobilization and manipulation techniques. These subtle differences may include, more force on disks during techniques involving&#xA0;more lumbar flexion, manipulations imparting more instant initial force, and manipulations imparting more force on the posterior/contralateral side of the disk; whereas, <a id="unilateral" data-tip="1551" target="_blank" href="/glossary-term/unilateral" class="glossary">unilateral</a> PA mobilizations result in more force on the posterior/ipsilateral side of the disk.</p>
<h4><strong>Amount of Force Necessary for Failure of Tissue</strong></h4>
<p>Unfortunately, relatively few comparative studies have been published that may aid in determining recommended upper limits of force during mobilization and manipulation techniques. A study by Sran et al. demonstrated that the mean load resulting in micro-fracture&#xA0;of the thoracic spine was&#xA0;479 N (SD 162 N), and the mean PA force imparted by a clinician was 145 N (SD 38 N); suggesting there is a considerable buffer between manipulation force and the force necessary to result in micro-fracture (38). Stemper et al. demonstrated that chest compression&#xA0;was&#xA0;1.8% - 4.5% of total chest depth during a typical maximum effort thoracic manipulation performed by an experienced chiropractor. Based on prior research and data using the&#xA0;<a title="Learn more about Abbreviated Injury Scale from ScienceDirect&apos;s AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/medicine-and-dentistry/abbreviated-injury-scale">Abbreviated Injury Scale</a>&#xA0;(AIS), this study suggests chiropractors use 20% of the force necessary to achieve a 10% increase in the risk of the lowest-rated <a id="compression" data-tip="1595" target="_blank" href="/glossary-term/compression" class="glossary">compression</a> injury (39).&#xA0;Boonyoung et al. used modeling to approximate the effect of a simulated 100 N PA lumbar mobilization on healthy and osteoporotic L1 vertebrae. The findings suggest that a healthy lumbar vertebra is most likely to fracture at the&#xA0;spinous process, whereas osteoporosis likely alters how stress and strain are absorbed by a vertebra increasing the risk that fracture would occur at the pedicles and/or laminae. Note, this study did not suggest that 100N of force was a sufficient force to result in a fracture (40). Based on the few studies currently available, it may be reasonable to suggest that the mean force used during manipulation and mobilization techniques is well below the minimum threshold for increased risk of tissue injury. However, some care may be warranted for osteoporotic patients based on a presumed increase in the risk of laminar fracture and the potential for neurologic injury.</p>
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        <h4><strong>Establishing an Optimal Range:</strong></h4>
        <p>Dozens of studies have recorded mean forces imparted during mobilization and manipulation techniques, but careful consideration must be given to how this data is interpreted. Studies that report mean values without comparison to tissue limits or outcomes are only helpful in perpetuating current practices, and they cannot be used to confirm that current practices are <a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a> or aid in determining <a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a> forces. Ideally, recommendations would establish a range from the minimal force required for intervention efficacy to the minimum force required to significantly increase the risk of tissue injury. Further, research would establish an <a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a> range (Goldilocks Zone) within these lower and upper limits, with the intent of recommending the amount of force required to maximize efficacy with minimal risk of injury. Although we may be able to establish norms based on the average forces imparted by a group of experienced therapists, without comparisons and correlations to outcomes and risk of injury, it is not possible to know whether&#xA0;average forces are <a id="optimal" data-tip="1571" target="_blank" href="/glossary-term/optimal" class="glossary">optimal</a> forces.</p>
      </td>
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Effect on Structures

Kinematics: Factors Affecting Joint Stiffness

<h4><strong>Toe and Creep</strong></h4>
<p>Several studies have alluded to mobilization-induced changes in stiffness exhibiting characteristics of mechanical toe and creep. In a study mentioned above, Lee et al. demonstrated that simulated lumbar central PA oscillatory mobilizations resulted in changes in stiffness that could be modeled by viscoelastic creep (15). Nicholson et al. developed an equation for force curves during simulated lumbar PA mobilizations, that resulted in a high correlation with raw data when&#xA0;compared to simpler <a id="model" data-tip="1471" target="_blank" href="/glossary-term/model" class="glossary">models</a> that only accounted for joint stiffness. The equation demonstrated that more attention should be given to the non-linear damping (toe) that occurs during the initial phase of mobilization, and the creep that occurs during the duration of the mobilization (41). Another study by Nicholson et al. hypothesized that the presence of non-linear stiffness may have an effect on the ability of practitioners to differentiate between stiffness levels during simulated PA mobilizations; however, the addition of padding to a force transducer had no effect on the clinician&apos;s ability to discriminate between stiffness levels (42). Shirley et al. demonstrated that stiffness and displacement increased during simulated PA lumbar mobilizations on 18 asymptomatic individuals, implying that an increase in displacement with a concurrent increase in stiffness is a normal response to mobilization (43). And, Latimer et al. demonstrated that differences in the force applied during the manual <a id="assessment" data-tip="1478" target="_blank" href="/glossary-term/assessment" class="glossary">assessment</a> of the lumbar spine resulted in different levels of stiffness assessed. Despite differences in force resulting in differing levels of stiffness, using a wider range of force increased inter-therapist <a id="reliability" data-tip="1515" target="_blank" href="/glossary-term/reliability" class="glossary">reliability</a> (44). These studies&#xA0;suggest that modeling the stiffness curve of joint mobilizations should consider an initial non-linear (toe) component, a curve influenced by the amount of force administered, and a change in force with repeated oscillations due to viscoelastic creep. These studies also suggest that a more complex <a id="model" data-tip="1469" target="_blank" href="/glossary-term/model" class="glossary">model</a> of joint stiffness does not negatively influence a practitioner&apos;s ability to differentiate stiffness levels, and the use of a wider range of forces may increase <a id="reliability" data-tip="1515" target="_blank" href="/glossary-term/reliability" class="glossary">reliability</a>.</p>
<h4><strong>The Direction of Force During Mobilization</strong></h4>
<p>The direction of force and angle of inclination may have a significant effect on the amount of joint stiffness encountered during joint mobilization and manipulation techniques. Snodgrass et al. investigated various grade mobilizations applied from C2 to C7 by 116 physical therapists, demonstrating a correlation between more vertical forces applied to C7 compared to more caudally inclined forces applied to C2, and an increase in <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> forces correlated with <a id="unilateral" data-tip="1551" target="_blank" href="/glossary-term/unilateral" class="glossary">unilateral</a> mobilizations (45). Allison et al. demonstrated that stiffness of the lumbar spine was less during vertical loads when compared to horizontal loads, and small differences in stiffness were demonstrated between vertical loads and vertical loads with an inclination angle (46). Caling et al. demonstrated that PA lumbar mobilizations performed with different angles of inclination resulted in different levels of stiffness, with vertical resulting in the largest amount of stiffness, sacral inclination resulting in 11% less stiffness, and <a id="cephalad" data-tip="1559" target="_blank" href="/glossary-term/cephalad" class="glossary">cranial</a> inclination resulting in 14% less stiffness. The direction of inclination also altered the displacement of adjacent segments. Interestingly, inclination angle did not affect stiffness at L5, perhaps due to the inherent stiffness of the L5 segment and stiffness of the sacroiliac joint (47). Viner et al. investigated the angle of force used during central PA lumbosacral mobilizations by 10 physiotherapists on 2 different patients. Although forces were generally vertical for all participants, mobilization angle inclined caudally for the lumbar spine and decreased in angle with each successive segment from L5 until <a id="cephalad" data-tip="1560" target="_blank" href="/glossary-term/cephalad" class="glossary">cranially</a> inclined for the cervical spine (48). In summary, these studies suggest the direction of force and angle of inclination have a significant effect on stiffness, including vertical loads resulting in less stiffness than horizontal loads, vertical inclination reducing stiffness when compared to &quot;pure&quot; vertical loads, and a practitioner bias toward <a id="caudal" data-tip="1557" target="_blank" href="/glossary-term/caudal" class="glossary">caudal</a> inclination in the lumbar spine and <a id="cephalad" data-tip="1559" target="_blank" href="/glossary-term/cephalad" class="glossary">cranial</a> inclination in the cervical spine.</p>
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        <h4><strong>Directing Force:</strong></h4>
        <p>Bereznick et al. designed a study that may imply there are negligible amounts of friction between the skin, underlying fascia, and thoracic vertebrae, demonstrating that a practitioner&apos;s hands often traveled more than the width of a single segment when attempting to apply an oblique force or &quot;hook a vertebra&quot; (49). This study implies that assertions that a force can be applied to a joint in a direction other than vertical, or close to vertical, are likely inaccurate.</p>
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<p></p>

<h4><strong>Support from Investing Structures</strong></h4>
<p>Several studies have investigated the influence of anatomy on joint stiffness. A study mentioned above by Lee et al. compared the stiffness of L3, L4 and L5, demonstrating that stiffness increased incrementally from L3 to L5 (28). Another study by Lee et al. compared stiffness during simulated PA mobilizations of&#xA0;L4, L1, T10, T7, and T4, demonstrating the greatest stiffness at L4 and the least stiffness at L1. This may suggest that segment stiffness is correlated with the amount of <a id="base-of-support" data-tip="1197" target="_blank" href="/glossary-term/base-of-support" class="glossary">support</a> from anatomical structures (e.g. L5 and sacrum for L4, ribs for thoracic segments, etc.). Note, these characteristics and anatomical <a id="base-of-support" data-tip="1197" target="_blank" href="/glossary-term/base-of-support" class="glossary">support</a> could not account for all variability between segments and individuals (50). Cattrysse et al. demonstrated that during mobilization only a weak to moderate correlation could be made between predicted motion and the length of anatomical structures (e.g. the alar ligament), including a 52% <a id="predictive-values" data-tip="1738" target="_blank" href="/glossary-term/predictive-values" class="glossary">predictive value</a> for sagittal ROM and 49% <a id="predictive-values" data-tip="1738" target="_blank" href="/glossary-term/predictive-values" class="glossary">predictive value</a> for the ratio of coupled rotation and <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> flexion (51). These studies imply that the anatomy of the joint and adjacent/supporting structures has a significant effect on joint stiffness, but cannot completely account for the variability between joints or individuals.</p>
<h4><strong>Position of the Spine, Pelvis, and Rib Cage</strong></h4>
<p>Joint position may also have a significant effect on joint stiffness.&#xA0;Edmondston et al. demonstrated that during a lumbar PA mobilization, mean stiffness was lowest in the neutral position,&#xA0;increased by 12.4% in extension, and increased by 31.9% in flexion. In all positions, lumbar PA stiffness was significantly greater at L5 than at L3 (52). Chansirinukor et al. demonstrated that fixation of the pelvis (preventing pelvic rotation) significantly increased stiffness during lumbar PA force, with the largest increase in stiffness noted for L5 (24%) and the least for L2 (6%) (53). Another study by,&#xA0;Chansirinukor et al. demonstrated that constraining the rib cage had a significant effect on the stiffness of&#xA0;T12-L4 during PA mobilizations (54). And, Shirley et al. demonstrated that stiffness of the L2 and L4 segments during central PA mobilization increased at the extremes of inspiration and exhalation, seemingly correlated with the participant&apos;s effort, and the greatest stiffness was noted during maximal exhalation (55). These studies demonstrate that lumbar spine stiffness during PA mobilization increases with increased flexion, extension, and/or a <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> pelvic tilt, when the pelvis or ribs are &quot;fixed&quot;, and during forced inspiration or expiration.</p>
<h4><strong>Participant&apos;s Physical Characteristics</strong></h4>
<p>Several studies demonstrate that a participant&apos;s physical characteristics may have a significant effect on joint stiffness.&#xA0;A study mentioned above by Lee et al. demonstrated that increased stiffness was correlated with more bodyweight, being older, and/or being male (50). Owens et al. investigated the lumbar PA stiffness of 192 patients with low back pain, demonstrating females exhibited more compliance (less stiffness) by a mean of 2 N/mm, and increased stiffness was correlated with being older, and/or having a higher body mass index (BMI). This study also demonstrated no significant correlation between stiffness and low back pain (56). Harms et al. compared grade III lumbar mobilization forces by a single experienced physical therapist on 30 young healthy subjects and 31 patients between 45 and 65 years of age, noting that median forces were 164 and 168 N, and that amplitude was slightly lower, but the frequency was slightly higher on the older group (57). This study may demonstrate practitioner bias in response to differences in joint stiffness correlated with the age of participants. These studies demonstrate that being male, being older, having a higher body mass index, and/or being heavier, may be correlated with increased joint stiffness. Although a correlation between low back pain and stiffness was not identified, this may be expected due to low back pain being correlated with <a id="hypomobility" data-tip="1673" target="_blank" href="/glossary-term/hypomobility" class="glossary">hypomobility</a> and <a id="hypermobility" data-tip="1677" target="_blank" href="/glossary-term/hypermobility" class="glossary">hypermobility</a>.</p>
<h4><strong>Muscle Activity, Fascia, and Joint Stiffness</strong></h4>
<p>A study by Lee et al. demonstrated that a maximal <a href="https://brookbushinstitute.com/article/erector-spinae" target="_blank" rel="noopener">extensor</a> contraction significantly increased stiffness during cyclical lumbar <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> to <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> forces, implying that extensor <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity may have an effect on perceived stiffness during PA mobilizations (58). This study suggests that extensor activity may alter lumbar spine stiffness, and have implications for practitioners treating lumbar dysfunction, especially acute low back pain.</p>

Kinematics: Factors Affecting Force During Mobilizations and Manipulations

<h4><strong>Hand Position and Grip</strong></h4>
<p>Studies have demonstrated that hand position may have a significant effect on force characteristics.&#xA0;Perle et al. investigated how hand configuration may affect the amount and location of force absorbed during a thoracic manipulation using force gauges and radiographs. The findings demonstrated that peak pressure was in the proximity of a practitioner&apos;s pisiform bone with an arched hand, and the hamate bone with a flat hand. Further, changing hand positions resulted in significant changes in force distribution and magnitude (59). Maher et al. compared&#xA0;a thumb grip to a pisiform grip during joint motion <a id="assessment" data-tip="1478" target="_blank" href="/glossary-term/assessment" class="glossary">assessment</a> of the spine, demonstrating that a thumb grip resulted in a bias toward more perceived stiffness; however, these differences did not affect <a id="reliability" data-tip="1515" target="_blank" href="/glossary-term/reliability" class="glossary">reliability</a> (60). A study by Nicholson et al. demonstrated a relationship between hand contact area and the ability of a practitioner to differentiate levels of stiffness (61). Several studies by Snodgrass et al. demonstrated correlations between force and thumb pain (62-64), including a correlation between thumb pain and higher forces among students, but thumb pain and lower forces among experienced therapists (64).&#xA0;These studies do not&#xA0;suggest that a single grip or hand position results in <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> outcomes. However, research does suggest that different hand positions and grips result in differences in force characteristics, force may be influenced by thumb pain, and there may be a correlation between contact area and the ability to discriminate stiffness. Based on these findings it may be recommended that a consistent hand configuration with sufficient contact area, that minimizes thumb stress, should be developed with the intent to optimize <a id="reliability" data-tip="1515" target="_blank" href="/glossary-term/reliability" class="glossary">reliability</a> and <a id="accuracy" data-tip="1218" target="_blank" href="/glossary-term/accuracy" class="glossary">accuracy</a>.</p>
<h4><strong>Gender&#xA0;</strong></h4>
<p>Four studies were located that demonstrate a significant difference in therapist force between genders. Forand et al. demonstrated preload force was significantly lower for females; however, all other force parameters were similar during lower thoracic manipulation (65). Pasquier et al. demonstrated that men exhibited higher mean peak force and mean rates of force development; however, women exhibited less variability in force&#xA0;during thoracic manipulations (65). Additionally, several studies by Snodgrass et al. demonstrated correlations between more force and mobilizations performed by male therapists or on male patients during cervical mobilizations performed by students and experienced therapists (62-64, 67). These studies may imply&#xA0;that differences in mean force when comparing men and women are exhibited in force characteristics requiring the most strength from the practitioner, specifically initial force, peak force, and rate of force development. No difference was demonstrated for most force characteristics including mean force, oscillation speed, differentiation between grades, and further, women may exhibit less variability. It is unlikely that any of the differences demonstrated have any significant effect on patient outcomes.</p>
<h4><strong>Experience</strong></h4>
<p>Several studies have compared the influence of student and clinician experience on&#xA0;therapist force during mobilization and manipulations. Snodgrass et al. investigated forces applied by students performing central and <a id="unilateral" data-tip="1551" target="_blank" href="/glossary-term/unilateral" class="glossary">unilateral</a> PA joint mobilizations on the cervical spine, grades I - IV, using an instrumented table. Findings demonstrated that mean peak force increased from grades I - IV, inter-therapist <a id="reliability" data-tip="1515" target="_blank" href="/glossary-term/reliability" class="glossary">reliability</a> was poor, and intra-therapist <a id="reliability" data-tip="1515" target="_blank" href="/glossary-term/reliability" class="glossary">reliability</a> was good. Higher forces were correlated with a student being earlier in the learning process (64).&#xA0;In another study by Snodgrass et al., 116 physiotherapists were compared to 120 physiotherapy students performing cervical mobilizations, demonstrating students generally applied lower forces at slower oscillation frequencies than practicing physiotherapists (contradicting the previous study) (67).&#xA0;Gagnon et al. demonstrated that physiotherapy students performing PA lumbar mobilizations applied lower mean forces for&#xA0;grades I and II than grades III and IV, and that experienced physiotherapists used similar oscillation frequency but a greater mean force for all grades when compared to students (68). Derian et al. compared differences in lumbar manipulation kinematics for experienced practitioners and student physical therapists, demonstrating that experts exhibited increased downward and linear pelvic velocity and increased modulation of <a id="ground-reaction-force" data-tip="1397" target="_blank" href="/glossary-term/ground-reaction-force" class="glossary">ground reaction forces</a> (69). Last, Loranger et al. compared force and perception of error from students and experienced clinicians attempting to achieve 300N of force during a thoracic manipulation on an instrumented manakin following a practice period. The findings demonstrate that the error rate was similar; however, preload forces were significantly less for 1st-year students when compared to all other groups, time-to-peak force decreased from 1st-year students to 5th-year students to experienced clinicians, and thrust force and thrust rate significantly increased with experience from 1st-year students to experienced professionals (70). These studies suggest that students and experienced clinicians exhibit similar <a id="accuracy" data-tip="1218" target="_blank" href="/glossary-term/accuracy" class="glossary">accuracy</a> of perception of error, similar inter-therapist, and intra-therapist reliability; however, peak force and rates of force development generally increase with experience.</p>

<h4><strong>Practitioners Modified Force</strong></h4>
<p>Several studies have demonstrated that practitioners can alter and differentiate force characteristics during mobilizations and manipulation techniques. Triano et al. investigated forces from 3 lumbar manipulation techniques on 11 healthy volunteers, using computer modeling to evaluate forces through vertebral structures. Findings suggest that practitioners may alter the amount of force by changing their intent, posture/position, speed, or technique (71). Owens et al. demonstrated that chiropractors could differentiate between light, moderate and heavy thrusts, and also exhibited significant control over direction, preferring to adjust the patient position so that the primary direction of force was vertical (72). These studies&#xA0;demonstrate that practitioners may significantly and purposefully modify force characteristics by altering intent, speed, direction, <a id="posture" data-tip="1658" target="_blank" href="/glossary-term/posture" class="glossary">posture</a>, and technique.</p>
<h4><strong>Comparing Techniques</strong></h4>
<p>Research has also compared the force characteristics of a variety of mobilization and manipulation techniques. In a study mentioned above, Triano et al. demonstrated that the technique chosen by the practitioner had a significant influence on force characteristics (71). Another study by Triano et al. compared the variance between 66 randomized direct break or rotatory break diversified procedures with the intent of manipulating C2 on 18 asymptomatic volunteers. Findings demonstrated that the 8 chiropractors in the study exhibited sagitally symmetric positions during the direct break technique, and only minor variations in <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> flexion and rotation during the <a id="pivot-joint" data-tip="1838" target="_blank" href="/glossary-term/pivot-joint" class="glossary">rotary</a> break technique, with the variations believed to accommodate variance in participant characteristics (73). Kawchuck et al. compared the peak force and duration of 5 cervical manipulation techniques, demonstrating that <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> break&#xA0;normalized mean peak force was 102.2 N and technique duration was 86.7 msec, Gonstead technique was 109.8 N and 91.9 msec, Toggle technique was 117.6 N and 47.5 msec, Activator technique was 40.9 N and 31.8 msec, and rotation technique was 40.5 N and 79.1 msec (74). Another study by Kawchuk et al. demonstrated that the use of a mechanical instrument (activator) reduced the amount of absolute variability in forces when compared to manual manipulation; however, the activator force was significantly lower and inter-therapist variability was still large for both techniques (75).&#xA0;Cambridge et al. compared preload force, the slope of thrust, instantaneous loading rate, duration, total force, and amplitude during 3 strategies for thoracic thrust manipulation, demonstrating that although most force characteristics were similar, there were a few significant differences between techniques (76). Last, Bell et al. compared forces during side-lying rotation lumbar manipulation with a push force, pull force, and at 3 different angles of hip flexion (0&#xB0;, 45&#xB0;, 90&#xB0;), demonstrating that the pull force, and 0&#xB0; of hip flexion, resulted in the fastest acceleration, highest velocities, highest forces and the most lumbar extension (77). In summary,&#xA0;research comparing techniques suggest that a few significant differences may be identified; however, most techniques exhibit similar force characteristics or differences in characteristics that still cluster around a relatively narrow range. The one exception may be techniques using the Activator which results in approximately half the force as other techniques with the same intent.&#xA0; These studies do not imply a <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> technique based on outcomes; however, it may be recommended that professionals develop a consistent repertoire of techniques to optimize <a id="reliability" data-tip="1515" target="_blank" href="/glossary-term/reliability" class="glossary">reliability</a> and <a id="accuracy" data-tip="1218" target="_blank" href="/glossary-term/accuracy" class="glossary">accuracy</a>.</p>
<h4><strong>Influence of Manual Fixation</strong></h4>
<p>A series of studies by Cattrysse et al. investigated the influence of manual fixation.&#xA0;Cattrysse et al. used 3D ultrasound to track the kinematics of the atlantoaxial joint on 20 fresh cadaver cervical spine specimens during cervical manipulation using 3 different manual fixation techniques (segmental, locked, and multi-segmental). Findings demonstrated little difference; however, moderate <a id="reliability" data-tip="1515" target="_blank" href="/glossary-term/reliability" class="glossary">reliability</a> and differentiation were exhibited by the 2 most experienced practitioners in the group (78). In an additional set of 2 studies, Cattrysse et al. demonstrated that during atlantooccipital mobilization, manual fixation significantly reduced <a id="axial-skeleton" data-tip="1292" target="_blank" href="/glossary-term/axial-skeleton" class="glossary">axial</a> rotation and <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> flexion, without significant influence on flexion/extension. Further, manual fixation appeared to &quot;lock&quot; lower segments, including the movement of the atlantoaxial joint, without significantly influencing the movement of the intended atlanto-occipital segment (79, 80). These studies suggest that&#xA0;various fixation techniques (segmental, locked, and multi-segmental) are likely similarly effective for significantly reducing <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> flexion and rotation of lower segments, without restricting motion of the intended segment.</p>
<h4><strong>Additional Variables Affecting Force and Interpretation of Force Data</strong></h4>
<p>Additional research demonstrates that certain variables may have an impact on the force characteristics of mobilization and manipulation in practice, as well as have a significant effect on how published force data should be interpreted. Herzog et al. demonstrated that forces exerted during manipulations are lower for the cervical spine and higher for the thoracic spine and sacroiliac joint, and a correlation was noted between preload force and peak force during manipulation (81). Maher et al. demonstrated that visual occlusion did not affect the <a id="accuracy" data-tip="1218" target="_blank" href="/glossary-term/accuracy" class="glossary">accuracy</a> of palpation, but did result in higher mean ratings of stiffness (82). Another study by Maher et al. demonstrated that the amount of plinth padding resulted in significant differences in stiffness curves (loading curve and the displacement at 30 N) exhibited during PA mobilizations of the thoracic and lumbar spine (83). A study by Herzog et al. demonstrated that the average peak force transmitted during a thoracic spine manipulation by an experienced clinician was 238.2 N; however, the average peak local force over a target area of 25 mm<sup>2</sup>&#xA0;was only 5N. This study suggests that global measures of force grossly overestimate local forces at the target site. Further, the peak pressure point moved 9.8 mm on average during the course of the manipulation (84). Symons et al. compared the mean peak force and duration of cervical manipulations performed by 2 chiropractors on 28 symptomatic and asymptomatic living subjects, and 5 cadavers. No significant differences were exhibited when comparing manipulations on symptomatic and asymptomatic living subjects; however, mean peak force was higher and duration shorter for manipulations on cadavers. The mean peak force on living subjects was 190.3 &#xB1; 85.5 N (mean &#xB1; SD) with a mean duration of 175 &#xB1; 100 ms, compared to a mean peak force on cadavers of 283.9 &#xB1; 53.6 N with a mean duration of 120 &#xB1; 30 ms (85). These studies imply that <a id="assessment" data-tip="1481" target="_blank" href="/glossary-term/assessment" class="glossary">evaluation</a> of force characteristics should consider visual occlusion, the amount of plinth padding, whether local or global forces were reported, the normal stiffness of the joint being assessed relative to other joints, and whether force was recorded on a cadaver or living participant.</p>

Nervous System

<h4><strong>H-reflex Attenuation</strong></h4>
<p>Several studies have demonstrated that mobilizations and manipulations of the spine have an effect on H-reflex (stretch reflex). Orikifar et al. demonstrated that sacroiliac joint manipulation resulted in a transient (approximately 20-seconds) increase in H-reflex amplitudes, despite resulting in no change in pain pressure threshold in the lumbar area of asymptomatic individuals (114). Dishman et al. demonstrated that lumbar manipulation had a larger effect on the attenuation of&#xA0;<a href="https://brookbushinstitute.com/article/gastrocnemius-plantaris">gastrocnemius</a>&#xA0;H-reflex&#xA0;than the side-lying loaded position used during set-up (117).&#xA0;And, a more recent RCT by Dishman et al. demonstrated similar findings, noting high-velocity lumbar rotation manipulation resulted in significant attenuation of H-reflex compared to side-positioning and loaded side-positioning, and further that the attenuation was similar for both symptomatic and asymptomatic individuals (118). Conversely,&#xA0;Suter et al. demonstrated that lumbar manipulation did not significantly alter H-reflex; and further, implied that any changes in H-reflex were the result of changes in position (side-lying versus <a id="prone" data-tip="1561" target="_blank" href="/glossary-term/prone" class="glossary">prone</a>) (119). Considering, this is the only study with opposing findings, and the RCT by Dishman et al (118) specifically compared manipulation to side-lying and loaded side-lying positions, it is likely reasonable to consider this a <a id="false-negative" data-tip="1201" target="_blank" href="/glossary-term/false-negative" class="glossary">false negative</a>, perhaps due to a lack of outcome measure <a id="sensitivity" data-tip="1226" target="_blank" href="/glossary-term/sensitivity" class="glossary">sensitivity</a> or an inadequate number of participants. In summary, these studies suggest that manipulation of the lumbar spine results in H-reflex attenuation immediately the following manipulation; and further, these findings occur regardless of position (side-lying or <a id="prone" data-tip="1561" target="_blank" href="/glossary-term/prone" class="glossary">prone</a>) and in symptomatic and asymptomatic individuals.</p>
<p>Additional studies have contributed to a more detailed understanding of the alterations to H-reflex following mobilizations and manipulations.&#xA0;An RCT by Murphy et al. demonstrated that sacroiliac joint manipulation resulted in a significant decrease in H-reflex of the <a id="ipsilateral" data-tip="1550" target="_blank" href="/glossary-term/ipsilateral" class="glossary">ipsilateral</a> leg, had no effect on the <a id="contralateral" data-tip="1549" target="_blank" href="/glossary-term/contralateral" class="glossary">contralateral</a> leg, and sham intervention had no effect on either leg.&#xA0;Further, the study was repeated with anesthetic cream over the SIJ to determine if the decrease in H-reflex was related to cutaneous afferent stimulation. Results were similar suggesting cutaneous input did not contribute to H-reflex attenuation (120). A comparison study by Dishman et al. demonstrated that inhibition of the H-reflex was not a systemic phenomenon, demonstrating that lumbar manipulation had a significant effect on tibial <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> H-reflex, but cervical manipulation did not (121). In another comparative study by Dishman et al., it was demonstrated that the attenuation of H-reflex was larger for the tibial <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> following lumbar manipulation than it was for the median <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> following cervical manipulation (122). Three studies mentioned in this review have demonstrated the transient nature of H-reflex attenuation, demonstrating a return to baseline measurements in 20 - 60 seconds (114, 121, 123). In summary,&#xA0;manipulation of the lumbar spine results in a transient (20-60 second) attenuation of the H-reflex for muscles of the <a id="ipsilateral" data-tip="1550" target="_blank" href="/glossary-term/ipsilateral" class="glossary">ipsilateral</a> innervated extremity in both symptomatic and asymptomatic individuals. Further, the attenuation is not significantly influenced by cutaneous input and occurs regardless of patient position (side-lying or <a id="prone" data-tip="1561" target="_blank" href="/glossary-term/prone" class="glossary">prone</a>).</p>
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        <h4><strong>Practical Implications</strong></h4>
        <p>A study by Floman et al. demonstrated that lumbar manipulation performed on patients with&#xA0;unilateral L5-S1 disc herniation who exhibited H-reflex latency responded with a significant improvement in H-reflex latency/threshold on the affected side, and a trend toward decreased latency on the unaffected sides (Note, the trend on the unaffected side did not reach statistical significance) (124). This study may suggest that a benefit of manipulation is a normalization of stretch reflex for innervated muscles.</p>
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<h4><strong>H-reflex and Mobilizations:</strong></h4>
<p>Relatively few studies have investigated the effects of mobilization on H-reflex. Dishman et al. demonstrated both mobilization and manipulation resulted in&#xA0;<a href="https://brookbushinstitute.com/article/gastrocnemius-plantaris">gastrocnemius</a>&#xA0;H-reflex attenuation, with a return to baseline 30-seconds after intervention (123). And, Bulbulian et al. demonstrated that H-reflex <a id="excitability" data-tip="1310" target="_blank" href="/glossary-term/excitability" class="glossary">excitability</a> was diminished by flexion mobilizations, but not rotation or <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> flexion mobilizations (125).&#xA0;These studies suggest that flexion/extension mobilizations of the spine likely have a similar effect on H-reflex threshold/amplitude as manipulations; however, mobilizations that are&#xA0;predominantly rotation or <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> flexion may not alter H-reflex.</p>
<h4><strong>V-wave and M-wave</strong></h4>
<p>Additional studies include the investigation of V-wave, M-wave, V/M ratios, and H/M ratios following manipulation. Grindstaff et al. demonstrated that <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> and <a id="proximal" data-tip="1564" target="_blank" href="/glossary-term/proximal" class="glossary">proximal</a> tibiofibular joint mobilizations resulted in a decrease in <a href="https://brookbushinstitute.com/article/fibularis-muscles" target="_blank" rel="noopener">fibularis longus</a> H-wave/M-wave (max) ratios, and <a id="distal" data-tip="1563" target="_blank" href="/glossary-term/distal" class="glossary">distal</a> tibiofibular joint manipulation decreased <a href="https://brookbushinstitute.com/article/soleus" target="_blank" rel="noopener">soleus</a>&#xA0;H-wave/M-wave (max) ratios for up to 20 minutes post manipulation (126). Azadvari et al. demonstrated that low back pain patients receiving lumbosacral manipulation exhibited a decrease in the&#xA0;<a href="https://brookbushinstitute.com/article/tibialis-anterior" target="_blank" rel="noopener">tibialis anterior</a>&#xA0;H-reflex threshold, but manipulation had no significant effect on H-wave or M-wave latency and&#xA0;had no significant effect on M-wave amplitude (127). Niazi et al. demonstrated that manipulation resulted in increased maximal voluntary contraction (MVC) measured by EMG and force, increased V/M ratio, and a reduction in H-reflex threshold for the <a href="https://brookbushinstitute.com/article/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> (128). And, Christiansen et al. demonstrated that manipulation of stiff spine segments in asymptomatic Taekwondo athletes resulted in a significant decrease in <a href="https://brookbushinstitute.com/article/soleus" target="_blank" rel="noopener">soleus</a> H-reflex thresholds and an increase in V-wave amplitudes when compared to controls (129).&#xA0;These studies suggest that manipulation and mobilization result in a transient (approximately 20 minutes) decrease in the H-reflex threshold, an increase in V-wave amplitude, and no significant effect on the M-wave threshold.</p>
<h4><strong>Velocity</strong></h4>
<p>Research suggests that the velocity of a manipulation influences the attenuation of H-reflex. Colloca et al. demonstrated that spinal <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> root responses (compound action potentials also noted during stretch reflex/H-reflex testing) occurred approximately 75% of the time during high-velocity manipulations, but did not occur during low-velocity sham manipulation (130). Cao et al. demonstrated that thrust manipulation resulted&#xA0;in an increase in the resting discharge rate of <a href="https://brookbushinstitute.com/article/erector-spinae">paraspinal</a> <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> spindles, regardless of the duration or amplitude of thrust, suggesting that <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> spindle response may be solely dependent on velocity (131). A preliminary report by Sung et al. noted similar findings, additionally demonstrating that as force and velocity approached those typically seen during manipulations there was a sudden increase in neural discharge (instantaneous frequency) of low&#xA0;threshold <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> mechanoreceptors, suggesting that response is dependent on surpassing a minimum threshold velocity (132). Last, an animal study (cats) by Pickar et al.&#xA0;suggests that one characteristic of spinal manipulation may be the capacity to load&#xA0;<a href="https://brookbushinstitute.com/article/erector-spinae">paraspinal</a>&#xA0;muscle spindles at a rate at which velocity <a id="sensitivity" data-tip="1226" target="_blank" href="/glossary-term/sensitivity" class="glossary">sensitivity</a> dominates over length <a id="sensitivity" data-tip="1226" target="_blank" href="/glossary-term/sensitivity" class="glossary">sensitivity</a> (133). This group of studies suggests that&#xA0;the attenuation of H-reflex is likely dependent on a manipulation achieving a minimum threshold velocity in which <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> spindle velocity <a id="sensitivity" data-tip="1226" target="_blank" href="/glossary-term/sensitivity" class="glossary">sensitivity</a> dominates over length sensitivity; further, H-reflex is likely not influenced by manipulation amplitude or duration.</p>

H-reflex, M-wave and V-wave Response

<p>Research suggests that mobilizations and manipulations result in central <a id="nervous-system" data-tip="1690" target="_blank" href="/glossary-term/nervous-system" class="glossary">nervous system</a> (CNS) mediated changes. Haavik-Taylor et al. demonstrated that manipulation of dysfunctional cervical segments of subclinical pain patients significantly shortened the transcranial magnetic stimulation (TMS)-induced cortical silent periods of the abductor pollicis brevis for approximately 20 minutes, implying cervical spine manipulations had an effect on the motor cortex (134).&#xA0;Lelic et al. used EEG and median <a id="nerve-cell" data-tip="1361" target="_blank" href="/glossary-term/nerve-cell" class="glossary">nerve</a> stimulation to demonstrate that manipulation of dysfunctional spine segments performed on patients with subclinical pain altered somatosensory processing at the cortical level, particularly within the prefrontal cortex (135). Daligadu et al. used TMS to demonstrate that manipulation performed on subclinical neck pain patients resulted in altered&#xA0;cerebellar inhibition when compared to healthy controls; and further, manipulation before a motor sequence learning task changed the cerebellar inhibition pattern to one similar to healthy controls (136). A study by Sparks et al. used functional MRI to compare cerebral activity and pain intensity via a standardized stimulus at the bed of the fingernail pre- and post-thoracic manipulation. The study demonstrated that thoracic manipulation resulted in a reduction in cerebral blood flow to the brain areas known collectively as the &quot;pain matrix&quot;, including a&#xA0;significant correlation between reduced activation of&#xA0;the insular cortex and decreased pain (137). These studies suggest that some of the effects of mobilization and manipulation result from cerebellar inhibition, changes to the motor cortex and somatosensory processing, and a reduction in the activation of the &quot;pain matrix&quot;, especially the insular cortex.</p>
<p>Additional studies suggest manipulations result in CNS-mediated facilitation. Haavik et al. demonstrated that manipulation of the spine resulted in TMS-induced input-output curves for both upper and lower extremity muscles with larger maximum motor evoked potentials and larger amplitudes of movement-related cortical potentials. Additionally, there were no changes in spinal measures (F-wave amplitudes), suggesting that increases in strength following manipulation were due to descending cortical drive and not spinal cord level changes (138). Similarly, Dishman et al. used TMS to demonstrate that lumbar manipulation resulted in a transient (20-60 seconds) but significant increase in maximum motor evoked potentials of the <a href="https://brookbushinstitute.com/article/gastrocnemius-plantaris" target="_blank" rel="noopener">gastrocnemius</a>&#xA0;(139). And in another study by Dishman et al., central motor facilitation following manipulation was specifically attributed to postsynaptic facilitation of&#xA0;<em>&#x3B1;-</em>motoneurons and/or corticomotor neurons innervating <a href="https://brookbushinstitute.com/article/erector-spinae">paraspinal</a> muscles (140). In summary,&#xA0;manipulation additionally results in some CNS facilitation that may result from the increased descending cortical drive and/or&#xA0;postsynaptic facilitation of&#xA0;<em>&#x3B1;-</em>motoneurons and/or corticomotor neurons.</p>
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        <h4><strong>Better Free-throw Percentage?</strong></h4>
        <p>In an interesting study by Humphries et al. that may be related to cortical <a id="integration" data-tip="1472" target="_blank" href="/glossary-term/integration" class="glossary">integration</a>, kinesthesia, or disinhibition; lower cervical manipulation resulted in a slight increase in made free-throw percentage in a group of basketball players (141). Although more research is needed, this study may imply a correlation between manipulation, CNS mediated changes, and improved <a id="accuracy" data-tip="1218" target="_blank" href="/glossary-term/accuracy" class="glossary">accuracy</a>.</p>
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<h4><strong>Mobilization versus Manipulation</strong></h4>
<p>Two studies investigated CNS-mediated changes following ankle mobilizations and manipulations. Harkey et al. demonstrated that a single session of ankle mobilization was effective for restoring dorsiflexion in participants with CAI; however, H-reflex and corticospinal pathways were unaffected (142). And, an RCT by Fisher et al. compared high-velocity thrust manipulation, joint mobilization of the tibiotalar joint, and a control group, demonstrating that the thrust manipulation group had an increase in corticospinal <a id="excitability" data-tip="1310" target="_blank" href="/glossary-term/excitability" class="glossary">excitability</a>, and the mobilization group had a decrease in corticospinal <a id="excitability" data-tip="1310" target="_blank" href="/glossary-term/excitability" class="glossary">excitability</a>. Further, only the thrust manipulation group demonstrated a significant increase in the maximal motor-evoked potential (MEP) amplitude of the <a href="https://brookbushinstitute.com/article/tibialis-anterior" target="_blank" rel="noopener">tibialis anterior</a> (143). Although current comparative research is limited to techniques applied to the ankle, these studies imply that manipulation, but not mobilizations, results in corticospinal facilitation and increased maximal motor-evoked potentials.</p>
<h4><strong>Comparing CNS and Reflexive Changes:</strong></h4>
<p>An RCT by Fryer et al. demonstrated that lumbar manipulation resulted in an increase in H-reflex amplitude, but a decrease in motor-evoked potentials (144). These findings may suggest that the CNS response to manipulations is primarily mediated by the spinal cord, with lesser influence from supraspinal structures.</p>
<h4><strong>Hormones and Neurotransmitter</strong></h4>
<p>Several studies have investigated the effects of manipulation and mobilization on <a id="hormone" data-tip="1268" target="_blank" href="/glossary-term/hormone" class="glossary">hormones</a> and neurotransmitters. An RCT by Molins-Cubero et al. demonstrated that lumbar manipulation performed on women with low back pain and primary&#xA0;dysmenorrhea resulted in a significant decrease in low back pain, increase in pain pressure <a id="sensitivity" data-tip="1226" target="_blank" href="/glossary-term/sensitivity" class="glossary">sensitivity</a>, increased mechano-sensitivity of both SIJs, had no effect on plasma levels of catecholamines, no effect on plasma levels of noradrenaline, but did have a significant effect on&#xA0;serotonin (145). An RCT by Sanders et al. demonstrated that lumbar manipulation performed on individuals with acute low back pain had a significant impact on acute low back pain, but did not result in changes in plasma beta-endorphin levels (146). And, A&#xA0;study by Puhl et al. demonstrated that thoracic manipulation directed at a <a id="hypomobility" data-tip="1676" target="_blank" href="/glossary-term/hypomobility" class="glossary">hypomobile</a> segment in the upper thoracic spine of asymptomatic subjects did not have a measurable effect on the plasma concentrations of norepinephrine or epinephrine (147). These studies suggest that manipulations do not alter plasma levels of catecholamines, endorphins, norepinephrine or epinephrine, but may have a significant effect on plasma serotonin levels.</p>
<p>Additional studies demonstrate a change in <a id="hormone" data-tip="1266" target="_blank" href="/glossary-term/hormone" class="glossary">hormone</a> response following manipulation. An RCT by Kokjohn et al. demonstrated side-lying manipulation resulted in a significant reduction in pain, levels of menstrual distress, and a significant reduction in plasma levels of KDGPF2a in a group of women with primary dysmenorrhea; however, a less significant decrease in&#xA0;KDGPF2a was also noted in the sham group (148). Two RCTs by Brennan et al. demonstrated that thoracic manipulation performed on asymptomatic individuals resulted in a burst of blood-born neutrophils primed for enhanced endotoxin-stimulated tumor necrosis factor production, and a significant increase in levels of substance P (149, 150). MacKawan et al. demonstrated that either a 10-minute treatment of joint mobilization or traditional Thai massage performed on individuals with non-specific low back pain reduced levels of pain and increased levels of substance P (151).&#xA0;An RCT by Sampath et al. demonstrated that thoracic manipulation performed on asymptomatic individuals resulted in a reduction in salivary cortisol, and changes in the testosterone/cortisol ratio for at least&#xA0;6 hours after intervention (152). And, an RCT by Valera-Calero, demonstrated that both cervical mobilization and manipulation resulted in similar increases in levels of cortisol (153). These studies suggest that manipulation may increase serotonin, substance P, and neutrophils primed for enhanced endotoxin-stimulated tumor necrosis factor, as well as reduce salivary cortisol (including increasing testosterone/cortisol ratio), and potentially&#xA0;increase plasma levels of KDGPF2a in menstruating women.</p>
<p>Additional studies show altered CNS neurotransmitter levels. An RCT by Didehdar et al. demonstrated that spinal manipulation resulted in significant changes in brain metabolites when compared to baseline and sham treatment groups. This includes increases in&#xA0;N-acetyl aspartate in the thalamus,&#xA0;anterior cingulate cortex, insula, and dorsolateral prefrontal cortex regions. Additionally, increases in choline were noted in the thalamus, insula, and somatosensory cortex regions, and increases in glutamate and glutamine levels were noted in the thalamus (154).&#xA0;An RCT by Paugmali et al. demonstrated that the initial hypoalgesic effects of an elbow mobilization with movement (MWM) for the treatment of <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> epicondylalgia were not antagonized by naloxone, which suggests that the analgesic effects of the mobilization were non-opioid-mediated (155). Additionally, Paungmali et al. demonstrated that the effect size of the analgesia did not decrease with repeated bouts, which may be further <a id="base-of-support" data-tip="1197" target="_blank" href="/glossary-term/base-of-support" class="glossary">support</a> that analgesia is non-opioid-mediated (156). These studies demonstrate that mobilizations and manipulations have a significant effect on levels of brain metabolites including&#xA0;N-acetyl aspartate,&#xA0;choline, glutamate, and glutamine levels; however, these techniques likely do not affect levels of endogenous opioids.</p>

Central Nervous System (CNS) Mediated Changes

<h4>Skin Conductance</h4>
<p>Several studies correlate changes in skin conductance and temperature with mobilization and manipulation techniques performed on the cervical and thoracic spine. La Touche et al. demonstrated that upper cervical mobilizations decreased craniofascial pain and increased skin conductance, respiratory rate, and heart rate in patients with cervico-craniofacial pain (157). An RCT by Sterling et al. demonstrated that mobilizations resulted in analgesia, increased skin conductance, decreased skin temperature, and enhanced <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity during the&#xA0;<a href="https://brookbushinstitute.com/article/deep-cervical-flexor-endurance-test">deep neck flexor </a><a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> endurance test, in patients with middle to lower cervical spine pain (158). Moulson et al. demonstrated that the application of cervical SNAGs to the C5/C6 intervertebral joint (with cervical right rotation) resulted in an increase in skin temperature and skin conductance in asymptomatic individuals (159). An RCT by Jowsey et al. demonstrated that grade III, central, <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> to <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> (PA) mobilizations to T4 resulted in skin conductance changes in the hand when compared to placebo controls, in asymptomatic individuals (160). Conversely, Packer et al. demonstrated that thoracic spine manipulation of the T3 vertebral segment did not result in skin temperature changes in the thoracic region (measured using infrared thermography) in asymptomatic individuals (161). Considering this is the only contradictory study and a different outcome measure was used, it may be reasonable to question the <a id="sensitivity" data-tip="1226" target="_blank" href="/glossary-term/sensitivity" class="glossary">sensitivity</a> of this outcome measure to detect sympatho-excitatory effects. These studies demonstrate that cervical and thoracic spine mobilizations and manipulations may increase skin conductance, skin temperature, respiratory rate, and heart rate, in both symptomatic and asymptomatic individuals. Further, in symptomatic individuals, these sympatho-excitatory effects occur in conjunction with improvements in patient outcome measures including pain, range of motion (ROM), and <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> recruitment.</p>
<p>Additional studies imply similar effects for lumbar spine and extremity mobilizations. An RCT by Tsirakis et al. demonstrated that lumbar spine mobilization with leg movement resulted in a significant increase in skin conductance of the lower extremity on the treated side of asymptomatic individuals when compared to sham and control interventions (162). An RCT by Moutzouri et al. demonstrated that central PA and SNAG mobilizations applied to the L4 spinous process had a significant effect on lower extremity skin conductance when compared to a sham intervention in asymptomatic individuals (163).&#xA0;Yu et al. demonstrated that end-range shoulder mobilizations improved shoulder internal rotation range of motion (ROM), and resulted in a significant increase in shoulder skin temperature in individuals with assessed ROM restriction (164). And, an RCT by Simon et al. demonstrated <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> to <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> shoulder mobilizations resulted in a significant increase in skin conductance when compared to control or placebo conditions (165). These studies demonstrate that mobilization and manipulation of the lumbar spine and extremities alter sympathetic <a id="nervous-system" data-tip="1690" target="_blank" href="/glossary-term/nervous-system" class="glossary">nervous system</a> activity, as implied by changes in skin conductance and temperature, concurrent with clinical outcomes such as ROM, in both symptomatic and asymptomatic individuals.</p>
<p>Additional details regarding the effects of mobilization and manipulation on sympathetic activity can be derived from comparative studies.&#xA0;Perry et al. demonstrated that lumbar manipulation resulted in a 255% increase in skin conductance compared to a 94% increase following McKenzie-type extension exercises (166). Another study by Perry et al. demonstrated that skin conductance changed more, and in a larger percentage of participants, following manipulations when compared to mobilizations. Further, manipulations performed in either direction resulted in the same change in skin conductance (167). An RCT mentioned above by Jiang et al. demonstrated that skin temperature of the upper extremity increased more from manual manipulation than <a id="distraction" data-tip="1813" target="_blank" href="/glossary-term/distraction" class="glossary">traction</a> or control conditions (168). Chiu et al. demonstrated that sympathetic efferent activity was correlated with the speed of mobilization, with faster mobilization resulting in larger effects on skin conductance and temperature (169). And, Harris et al. used fingertip skin temperature to demonstrated that the sympathetic effect of spinal manipulation differed by segment, with skin temperatures (and blood flow) decreasing with cervical and lower lumbar manipulations, and skin temperature (and blood flow) increasing during manipulation of the thoracic and upper lumbar spine (170). These studies imply that mobilization and manipulation may result in larger sympatho-excitatory effects than therapeutic exercise; that mobilization may result in larger changes than <a id="distraction" data-tip="1813" target="_blank" href="/glossary-term/distraction" class="glossary">traction</a>, that higher velocity mobilizations and manipulations may result in larger effects; and further, that cervical and lower lumbar manipulation may result in different sympatho-excitatory effects than upper lumbar and thoracic manipulation.</p>
<h4><strong>Cardiovascular Changes</strong></h4>
<p>In addition to changes in skin <a id="conductivity" data-tip="1306" target="_blank" href="/glossary-term/conductivity" class="glossary">conductivity</a> and temperature, mobilizations and manipulations induce cardiovascular changes that may be attributed to altered sympathetic <a id="nervous-system" data-tip="1690" target="_blank" href="/glossary-term/nervous-system" class="glossary">nervous system</a> activity.</p>
<p>Several studies have investigated sympatho-excitatory effects resulting from cervical mobilizations and manipulations. A randomized control <a id="randomized-control-trial" data-tip="1407" target="_blank" href="/glossary-term/randomized-control-trial" class="glossary">trial</a> (RCT) by Yung et al. demonstrated that cervical mobilizations performed on asymptomatic individuals resulted in a transient decrease in systolic blood pressure when compared to controls (171). Another RCT by Yung et al. demonstrated that mechanical neck pain patients exhibited a reduction in pain and a transient decrease in blood pressure following <a id="anterior" data-tip="1566" target="_blank" href="/glossary-term/anterior" class="glossary">anterior</a> to <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> (AP) and <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> cervical mobilizations; however, it was noted that some normotensive participants exhibited a spike in systolic blood pressure immediately following the techniques (172). An RCT by Vicenzino et al. demonstrated that cervical&#xA0;lateral <a id="glide" data-tip="1598" target="_blank" href="/glossary-term/glide" class="glossary">glide</a> mobilization resulted in a significant increase in diastolic and systolic blood pressure, heart rate, and respiratory rate in asymptomatic individuals when compared to placebo and control conditions (173). Similarly, an RCT by McGuiness et al. demonstrated that cervical PA mobilizations intended for the C5/C6 segment resulted in a significant increase in diastolic and systolic blood pressure, heart rate, and respiratory rate in asymptomatic individuals when compared to placebo and control conditions (174). This collection of RCTs demonstrate that cervical mobilization and manipulation result in transient changes in blood pressure, heart rate, and respiratory rate. It may be noteworthy that transient alterations in blood pressure may include increases, decreases, changes to systolic pressure only, or changes of both systolic and diastolic blood pressure.</p>
<p>A study mentioned above by Paugmali et al. demonstrated that elbow mobilization with movement (MWM) performed on individuals with <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> epicondylalgia resulted in similar changes in heart rate, blood pressure, and cutaneous sudomotor and vasomotor function (94). This study may suggest that sympatho-excitatory effects can be anticipated following mobilization and manipulation of the extremities.</p>
<p>Some studies show similar results following thoracic mobilizations. An RCT by Minarini et al. demonstrated that thoracic manipulation of an arbitrarily chosen level in asymptomatic individuals had a small but significant effect on heart rate variability (175). A cross-over <a id="randomized-control-trial" data-tip="1407" target="_blank" href="/glossary-term/randomized-control-trial" class="glossary">trial</a> by Budgell et al. demonstrated that thoracic manipulation performed on asymptomatic individuals had a small but significant effect on heart rate variability when compared to a sham procedure (176). Ghaffer et al. demonstrated that thoracic mobilization performed on healthy adults resulted in a sudden elevation in heart rate, respiratory rate, and blood pressure without any significant change in blood oxygen saturation (177). Last, Ward et al. demonstrated thoracic manipulation performed on hypertensive patients resulted in a transient change in atria and ventricle activity (178). These studies may imply that thoracic mobilizations and manipulations are likely to have an effect on heart rate variability, blood pressure, and respiratory rate; however, it is unlikely to have any effect on O2 saturation.</p>
<p>Additional studies may suggest that thoracic mobilizations and manipulations have less consistent effects on cardiovascular signs of increased sympathetic <a id="nervous-system" data-tip="1690" target="_blank" href="/glossary-term/nervous-system" class="glossary">nervous system</a> activity. Another study by Ward et al. demonstrated that thoracic manipulation performed on young, normotensive individuals had no effect on heart rate variability, pulse ox (oxygen saturation), or blood pressure (179). An RCT by Sampath et al. demonstrated that thoracic manipulations performed on asymptomatic individuals had no effect on heart rate variability or oxyhemoglobin concentration of the right calf <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> (152). An RCT by de Araujo et al. investigated the effects of two thoracic manipulation techniques, demonstrating that neither technique had a significant effect on heart rate variability or <a href="https://brookbushinstitute.com/article/tibialis-anterior" target="_blank" rel="noopener">tibialis anterior</a> pain pressure threshold (180). Another RCT by de Araujo et al. demonstrated that&#xA0;mobilization of the thoracic spine performed on asymptomatic individuals, regardless of oscillation speed, did not have a significant effect on pain pressure threshold or heart rate variability in asymptomatic individuals (181). And, da Silva et al. demonstrated that thoracic manipulation did not alter the respiratory rate or heart rate more than a placebo manipulation in patients with rotator cuff tendinopathy; however, both manipulation and placebo groups exhibited significant differences when compared to asymptomatic individuals who exhibited no change (182). These studies suggest&#xA0;that thoracic manipulation and mobilization may not consistently result in sympatho-excitatory effects, regardless of the technique or speed of oscillation; however, the majority of these studies, resulting in contradictory findings, were performed with asymptomatic participants.</p>
<p>Several studies have attempted to compare the sympathoexcitatory effects resulting from mobilizations and manipulations on various joints and populations.&#xA0;Welch et al. demonstrated that cervical manipulations resulted in sympathetic <a id="nervous-system" data-tip="1690" target="_blank" href="/glossary-term/nervous-system" class="glossary">nervous system</a> excitation, including decreased diastolic blood pressure and increased pulse pressure. Conversely, thoracic manipulations likely increased parasympathetic activity as evidenced by a moderate effect size for&#xA0;decreased pulse pressure, despite this trend failing to reach statistical significance&#xA0;(183). An RCT by Win et al. demonstrated that cervical manipulation resulted in larger changes in systolic blood pressure and heart rate variability in individuals with neck pain when compared to asymptomatic individuals (184). An RCT by Roy et al. demonstrated that lumbar manipulation had a significant effect on heart rate variability for symptomatic individuals, but not asymptomatic individuals when compared to sham manipulation (185).&#xA0;An&#xA0;RCT by Alonso-Perez compared cervical manipulation, cervical mobilization, and cervical <a id="lateral" data-tip="1567" target="_blank" href="/glossary-term/lateral" class="glossary">lateral</a> <a id="glide" data-tip="1598" target="_blank" href="/glossary-term/glide" class="glossary">glide</a> mobilization, demonstrating that all techniques increased pain pressure threshold at the cervical spine and elbow, that mobilization techniques resulted in larger increases in pain pressure threshold than manipulation, and catastrophizing by the patient only reduced manipulation effectiveness when levels were high and had no effect when levels were low or moderate (186). Vicenzino et al. demonstrated that no correlation was found between the level of patient stress, pain perception, and sympathoexcitatory response resulting from cervical mobilization in asymptomatic individuals (187). These studies suggest that&#xA0;sympatho-excitatory effects may be anticipated following both mobilization and manipulation techniques, cervical and thoracic techniques may result in opposite effects, symptomatic individuals may exhibit larger changes than asymptomatic individuals, and these effects are only influenced by patient stress when stress results in high levels of catastrophizing during manipulation techniques.</p>
<h4><strong>Blood Pressure Treatment:</strong></h4>
<p>Studies have investigated whether mobilization and manipulation-induced sympatho-excitatory effects have the potential to decrease high blood pressure. A pilot RCT by Plaugher et al. demonstrated that 2-months of chiropractic manipulation did not significantly alter resting blood pressure in hypertensive patients (188). And a sham-controlled <a id="randomized-control-trial" data-tip="1407" target="_blank" href="/glossary-term/randomized-control-trial" class="glossary">trial</a> by Goertz et al. demonstrated that cervical manipulation had a transient effect on blood pressure when performed on pre-hypertensive or stage-1 hypertensive participants (systolic blood pressure from 135 -159 mm Hg, and diastolic blood pressure from 85&#xA0; - 99 mm Hg); however, no significant change was noted in resting blood pressure following 6-weeks of regular cervical manipulation (189). These findings suggest that the sympatho-excitatory effects following mobilization and manipulation are transient, and do not have a therapeutic benefit <a id="relevance" data-tip="1505" target="_blank" href="/glossary-term/relevance" class="glossary">relevant</a> to the treatment of high blood pressure.</p>

Sympatho-excitatory Effects

Muscle Activity

<h4><strong>Shoulder Muscles</strong></h4>
<p>Research has also investigated the effects of shoulder mobilizations on <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity, which may result in more transient effects than mobilization and manipulation of other joints. A pilot study by Swanson et al. demonstrated that&#xA0;grade III <a id="posterior" data-tip="1565" target="_blank" href="/glossary-term/posterior" class="glossary">posterior</a> shoulder mobilizations performed on asymptomatic individuals resulted in increased activity of the&#xA0;<a href="https://brookbushinstitute.com/article/supraspinatus">supraspinatus</a>&#xA0;and&#xA0;<a href="https://brookbushinstitute.com/article/infraspinatus-and-teres-minor">infraspinatus</a>, approaching activity levels exhibited when performing shoulder abduction (221). Ribeiro et al. demonstrated that sustained force during shoulder mobilization with movement (MWM) performed on asymptomatic individuals resulted in a decrease in shoulder <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity during mobilization; however, the decrease in <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity only lasted while performing the technique (222). Additionally, another study by Ribeiro et al. demonstrated that grade IV <a id="inferior" data-tip="1569" target="_blank" href="/glossary-term/inferior" class="glossary">inferior</a> shoulder mobilizations did not affect shoulder or scapular <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity immediately following the mobilization in asymptomatic individuals (223). These studies may imply that shoulder mobilizations have a significant effect on <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity during the intervention; however, the effects on <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity may not persist.</p>
<h4><strong>Gluteus Maximus and Gluteus Medius</strong></h4>
<p>Several studies have demonstrated that similar effects can be expected following mobilization of the extremities. Yerys et al. demonstrated that grade IV PA hip mobilizations performed on asymptomatic individuals resulted in an immediate increase in&#xA0;<a href="https://brookbushinstitute.com/article/gluteus-maximus">gluteus maximus</a>&#xA0;strength when compared to sham mobilization (grade I mobilizations) (219). And, Makofsky et al. demonstrated Grade IV <a id="superior" data-tip="1570" target="_blank" href="/glossary-term/superior" class="glossary">superior</a> to <a id="inferior" data-tip="1569" target="_blank" href="/glossary-term/inferior" class="glossary">inferior</a> hip mobilizations performed on asymptomatic participants resulted in an immediate increase in hip abductor (<a href="https://brookbushinstitute.com/article/gluteus-medius">gluteus medius</a>) <a id="torque" data-tip="1294" target="_blank" href="/glossary-term/torque" class="glossary">torque</a> when compared to sham hip mobilization (grade I mobilizations) (220). These studies suggest that hip mobilization alone may have a significant effect on&#xA0;<a href="https://brookbushinstitute.com/article/gluteus-medius">gluteus medius</a>&#xA0;and&#xA0;<a href="https://brookbushinstitute.com/article/gluteus-maximus">gluteus maximus</a>&#xA0;muscle activity and strength.</p>
<h4><strong>Knee Muscles</strong></h4>
<p><span style="color: #000000;">Conversely, knee mobilizations may have significant and lasting effects on <a href="https://brookbushinstitute.com/article/quadriceps-vastus-muscles">quadriceps</a> activity. An&#xA0;RCT by Kaya et al. demonstrated that knee mobilizations for the treatment of knee osteoarthritis had an immediate effect on&#xA0;<a href="https://brookbushinstitute.com/article/quadriceps-vastus-muscles">quadriceps</a>&#xA0;strength&#xA0;(224). </span><span style="color: #000000;">An</span><span style="color: #000000;">&#xA0;RCT by Courtney et al. demonstrated that knee mobilizations performed on knee osteoarthritis patients reduced <a id="sensitivity" data-tip="1226" target="_blank" href="/glossary-term/sensitivity" class="glossary">sensitivity</a> of the flexor withdrawal reflex, primarily by reducing <a href="https://brookbushinstitute.com/article/biceps-femoris" target="_blank" rel="noopener">biceps femoris</a>&#xA0;activity and knee flexor <a id="torque" data-tip="1294" target="_blank" href="/glossary-term/torque" class="glossary">torque</a> (95). And, Ghanbari et al. demonstrated that knee mobilization performed on healthy participants increased <a href="https://brookbushinstitute.com/article/quadriceps-vastus-muscles">quadriceps</a>&#xA0;maximal voluntary isometric contraction (MVIC) for at least&#xA0;30 minutes (225). These studies demonstrate that knee mobilizations have a significant and lasting effect on&#xA0;<a href="https://brookbushinstitute.com/article/quadriceps-vastus-muscles">quadriceps</a> and <a href="https://brookbushinstitute.com/article/biceps-femoris" target="_blank" rel="noopener">biceps femoris</a> activity, in both symptomatic and asymptomatic individuals.&#xA0;</span></p>
<h4><strong>Ankle Muscles&#xA0;</strong></h4>
<p>Only one study was found investigating the effect of ankle mobilization on ankle <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> activity and strength. An RCT by Ersoy et al. demonstrated that grade III ankle mobilizations performed on asymptomatic individuals resulted in a significant increase in dorsiflexor <a id="muscle-cell" data-tip="1781" target="_blank" href="/glossary-term/muscle-cell" class="glossary">muscle</a> strength for at least 30 minutes when compared to sham control (grade I mobilizations) (226). This study may be evidence that ankle mobilization may increase dorsiflexor activity; however, a reduction in resistance to dorsiflexion may also result in increased <a id="torque" data-tip="1294" target="_blank" href="/glossary-term/torque" class="glossary">torque</a>. Further research is needed.</p>

Muscle Activity: Additional Considerations

Bibliography

<p>&copy; 2021 Brent Brookbush</p>
<p>Questions, comments, and criticisms are welcomed and encouraged.</p>

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>

<strong>Accuracy</strong> - 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.

<strong>Adenosine triphosphatase (ATPase):</strong> 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>

<b>Adenosine triphosphate (ATP): </b>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>

<strong>Algometry</strong> - 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>

<span class="_Tgc"><b>All-or-none</b> <b>principle</b> - 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.</span>

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 <em>anterior</em> aspect of the head

<strong>Appendicular Skeleton</strong> - 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.

<strong>Arthrokinematic Motion</strong> - 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;

<strong>Assessment</strong><em> -</em> 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><strong>"Clear" the Patient/Client for Intervention</strong> - 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 <em>Calf Squeeze (Thompson) Test</em> 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><strong>Highlight Contraindications - </strong>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><strong>Refine Exercise/Intervention Selection</strong>: 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 <em>Refine Exercise/Intervention Selection</em>, 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 <em>Clearance</em> to resume rehab activities.  Further, that same patient may return to the human movement professional with a list of <em>Contraindicated Activities</em> from the physician. - <em>"When in doubt, refer out!"</em>

<strong>Axial Skeleton</strong> - 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 <span class="foreign">axis</span> "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>".

<strong>Balance</strong> - 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)

<strong>Base of support (BoS)</strong> - 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.

<strong>Case-control Study</strong> - 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. <i>American journal of epidemiology</i>, <i>134</i>(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<em> caudally</em>.

<strong>Center of mass (CoM)</strong> - an object's mean position of mass; that is, a point that is perfectly surrounded by an equal amount mass in all directions.

<b>Center of gravity (CoG)</b> - point where <b>gravity</b> 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 <em>cephalad</em>.

<strong>Cohort Study</strong> - 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>

<strong>Comparable Sign:</strong> 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.

<strong>Concave (Concavity)</strong> - 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>

<strong>Concordant Sign</strong> - The patient's specific pain, symptom or complaint.<span style="color: #ff0000;"> </span>
<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>

<strong>Conductivity</strong>: 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>

<strong>Contractility: </strong>The ability to shorten (1).
<ul>
 	<li><strong>Contractility</strong>: 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.

<strong>Convex (Convexity)</strong> - 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>

<strong>Correlational Research</strong> - 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. <em>J. Phys. Ther. Sci. </em>26: 961-964</a></li>
</ol>

<strong>Counter-nutation</strong> - 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;

<strong>Crossover (Study) Design</strong> - 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. <em>Journal of Human Kinetics, 58, 197-206.</em> </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) <em>Journal of Medical Science</em> 5(1). 52-54</a></li>
</ol>

<strong>Cytokine</strong> - 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. <em> Journal of Manual &amp; Manipulative Therapy</em>. 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 <em>distal</em> end of the leg.

An arthrokinematic motion - a <span class="_Tgc">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.</span>

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 <em>dorsal</em> 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<span class="_Tgc"> alteration of normal kinematics.</span>

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.

<strong>Elasticity</strong>: 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). <i>Anatomy &amp; physiology</i>. New York (NY): WCB/McGraw-Hill.</li>
</ol>

<strong>Equilibrium</strong> - 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"><strong>Evidence-based medicine (practice)</strong> 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. <i>Bmj</i>, <i>312</i>(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>

<strong>Excitability:</strong> The ability of a cell to <span class="hvr">change</span> in <span class="hvr">membrane</span> <span class="hvr">conductance</span> as a <span class="hvr">response</span> to <span class="hvr">stimulation.
</span>
<ul>
 	<li><span class="hvr">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.
</span></li>
</ul>
<ol>
 	<li>Saladin, K. (2012). Anatomy &amp; Physiology: The unity of form and function. (6th ed.). New York: McGraw-Hill.</li>
</ol>

<strong>Excitation threshold:</strong> 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>

<strong>Exercise Progression</strong> - 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>

<strong>Exercise regression</strong> - 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>

<strong>Experimental Research</strong> - 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. <em>Journal of Strength and Conditioning Research, 27</em>(11), 2997-3000.</a></li>
</ol>
&nbsp;

<strong>Extensibility</strong>: 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>

<strong>False Negative </strong>- 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>

<strong>False Positive </strong>- 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.

<strong>Fibromyalgia</strong> - A loosely defined diagnosis that is associated with a combination of widespread pain <i>in combination with</i> 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. <i>Fibromyalgia Syndrome and Widespread Pain: From Construction to Relevant Recognition</i>.</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. <i>Arthritis &amp; Rheumatism: Official Journal of the American College of Rheumatology</i>, <i>33</i>(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. <i>The Clinical journal of pain</i>, <i>27</i>(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. <i>PAIN®</i>, <i>145</i>(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. <i>Spine</i>, <i>20</i>(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. <i>Spine</i>, <i>20</i>(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>

<strong>H-Band</strong> - 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) (<em>biological holism</em>) - (from Greek <i>holos</i> "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]. <em class="EmphasisTypeItalic ">Holism and evolution</em>. 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.

<strong>Hormone: </strong>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. <i>Scandinavian journal of clinical and laboratory investigation</i>, <i>60</i>(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.

<strong>Hyperplasia</strong> 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.

<strong>Muscular hypertrophy</strong> 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.

<strong>I-Band</strong> - 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. <em>International Journal of Health and Rehabilitation Sciences</em>. 2(4): 186-191</a></li>
</ol>

An anatomical direction; toward the bottom (below)

Example, the mouth is <em>inferior</em> 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.

<strong>Intermuscular Coordination</strong> - Optimal timing and motor unit recruitment of agonists, antagonists, synergists, neutralizers, stabilizers and fixators.

<strong>Example: Role of Muscles during Hip Extension</strong>
<ul>
 	<li><strong><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>:</strong>  <a href="https://player.vimeo.com/external/82855344.hd.mp4?s=54c3e7d98fb9d4e0af8d282c85ba9b3e">Gluteus maximus</a></li>
 	<li><strong><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>:</strong> <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><strong><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>:</strong> <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><strong><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>:</strong> <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><strong><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>:</strong> <a href="https://brentbrookbush.com/articles/muscular-anatomy/deep-rotators-of-the-hip/">Deep rotators of hip</a></li>
 	<li><strong><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>: </strong><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 <strong>isoform</strong>, or variant, is a member of a set of similar proteins, that originate from the same gene, or gene family.<sup id="cite_ref-2" class="reference"></sup>
<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 <em>kinetic chain</em>, 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).

<strong>Latent Trigger Point</strong> - 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, <em>Travell &amp; Simmons’ Myofascial Pain and Dysfunction, The Trigger Point Manual, Volume 1. Upper Half of Body: Second Edition</em>,© 1999 Williams and Wilkens</li>
</ol>

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

<strong>Length/Tension Relationship</strong> - 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. <i>The Journal of physiology</i>, <i>184</i>(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. <i>The Journal of Physiology</i>, <i>183</i>(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. <i>Journal of neurophysiology</i>, <i>71</i>(3), 874-881.</li>
 	<li>Lieber, R. L. (2002). <i>Skeletal muscle structure, function, and plasticity</i>. Lippincott Williams &amp; Wilkins.</li>
</ol>
&nbsp;

<span class="_Tgc"><strong>Levels of Evidence</strong> - 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.
</span>

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. <i>Western Journal of Medicine</i>, <i>170</i>(6), 348.</li>
</ol>

<strong>Likelihood Ratios</strong> - 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><strong>Positive Likelihood Ratio (LR+)</strong> - The ratio of a positive test result in people with the pathology to a positive test result in people without the pathology.</li>
 	<li><strong>Negative Likelihood Ratio (LR-)</strong> - 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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