Research Review: Deep Neck Flexor Inhibition Occurs in Individuals with Chronic Neck Pain
By Nicholas Rolnick SPT, MS, CSCS
Edited by Brent Brookbush DPT, PT, COMT, MS, PES, CES, CSCS, H/FS
Original Citation: Jull G, Falla D. Does increased superficial neck flexor activity in the craniocervical flexion test reflect reduced deep flexor activity in people with neck pain? Manual Therapy. 2016; 25: 43-47. ABSTRACT
Why the Study is Relevant: The location of the deep neck flexors (DNF) , on the anterior surface of the cervical spine, has prohibited researchers from directly measuring muscle activity. This 2016 study is the first to use digital imaging and electromyography to confirm the hypothesized correlation between superficial anterior neck muscle over-activity (sternocleidomastoid) and inhibition of the DNF in those with chronic neck pain (1-3). The study should be applauded for its novel methodology and design.
![Dr. Brent Brookbush, DPT starts palpation of the sternocleidomastoid at the base of the mastoid process](/_next/image?url=https%3A%2F%2Fcdn.sanity.io%2Fimages%2Fobhirpvy%2Fproduction%2Fb9f7791883e713426561edc626e3c05276376ac8-640x360.jpg%3Fw%3D650%26fm%3Dwebp%26q%3D60&w=3840&q=75)
Palpation of the Sternocleidomastoid
Study Summary
Study Design | Cohort Study | |||||||||||||||||||||||||||||||||||
Level of Evidence | IIB Evidence from at least one other type of quasi-experimental study | |||||||||||||||||||||||||||||||||||
Subject Characteristics | Gender and Age (± Standard Deviation):
Inclusion Criteria:
Exclusion Criteria:
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Methodology | Prior to the start of the study, each participant rated her pain on the Numerical Rating Scale (NRS) and perceived function using the Neck Disability Index (NDI). Pre-Study Measures - Electromyography (EMG)
Cranio-cervical flexion ROM was determined for each participant during each stage using digital imaging that had been described in earlier studies. Each participant performed the cranio-cervical flexion test twice at the 5 different levels of pressure (22, 24, 26, 28 and 30 mm Hg) prior to data collection. Each position was held at each level for 10 seconds before progressing to the next level, with a 30-second rest between levels. This served to familiarize the participants to the required pressure.
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Data Analyses |
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Outcome Measures |
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Results |
Correlation between DNF and SCM nRMS values across the five stages: r = -0.45; p < 0.01 Correlation between DNF and AS nRMS values across the five stages: r = -0.34; p = 0.053 Our Conclusions Chronic neck pain appears to be correlated with DNF inhibition and synergistic dominance of the sternocleidomastoid. This implies that the DNF may play an important role in optimizing cervical motion and should be selectively activated in those individuals displaying signs of cervical dysfunction. Further, manual practitioners may consider sternocleidomastoid release prior to DNF Activation . Conclusions of the Researchers In individuals with chronic neck pain, higher levels of superficial neck flexor activity is associated with lower levels of DNF activity. Future studies should investigate motor control strategies in these individuals to further shape clinical practice. ![]() Anterior Cervical Spine in Cadaveric Dissection - By Anatomist90 - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=19544659 Review & Commentary: This groundbreaking study confirms the hypothesis (1-3) that a reduction in deep neck flexor (DNF) activity is correlated with an increase in sternocleidomastoid activity, and chronic neck pain. This study was the first to place electrodes on the deep neck flexors (DNF) with a suction catheter through the nose to the posterior oropharyngeal wall. The study had many methodological strengths, including:
Weaknesses that should be noted prior to clinical integration of the findings include:
How This Study is Important: This landmark study confirms that DNF inhibition occurs in individuals with chronic neck pain. The findings also show a moderate correlation between increased activity of the sternocleidomastoid (r = -0.45) and anterior scalenes (r = -0.34), and decreased activity of the DNF during the cranio-cervical flexion test. How the Findings Apply to Practice: Human movement professionals should consider assessing activity of the DNF in those with chronic neck pain using the cranio-cervical flexion test or deep cervical flexor endurance test . If assessment implies DNF under-activity, DNF Activation should likely be included in a routine designed to optimize motion. In addition, release of commonly overactive synergists (sternocleidomastoid, anterior scalenes, levator scapulae , and upper trapezius ) may be beneficial, especially when done prior to DNF Activation . How does it relate to Brookbush Institute Content? The Brookbush Institute's (BI) predictive model of upper body dysfunction (UBD) (as well as the Cervicothoracic Dysfunction Model in development) characterizes the deep neck flexors (DNF) (longus colli, longus capitis, rectus capitis anterior, and rectus capitis lateralis) as "long/underactive." In UBD , individuals will likely present with excessive flexion (limited extension) at the cervico-thoracic junction, cervical facet dysfunction related to hypertonicity of the levator scapulae , upper trapezius and sternocleidomastoid (SCM), and potentially elevation of the 1st rib due to hypertonicity in the scalene muscles. This presentation perpetuates inhibition of the local stabilizers (DNFs ) and helps feed-forward compensatory over-activity of the superficial neck flexors, as described in the current study. An individual presenting with cervicothoracic dysfunction would present similar to the compensation pattern described above; however, further consideration would be given to the upper cervical spine, and the shoulder and shoulder girdle would not remain a priority during intervention. A sample protocol for addressing cervical dysfunction and inhibited DNF activity would be: releasing the anterior scalenes, SCM, upper trapezius , levator scapulae and sub-occipitals ; mobilizing the cervical and thoracic spine (if within scope of practice); activating the DNFs , and potentially integrated DNF activity into other core and upper body movement patterns. The videos below demonstrate some techniques that may be implicated by this study: Brookbush Institute VideosDeep Cervical Flexor Endurance Test Sternocleidomastoid Manual Static Release Scalene Static Manual Release Lewit Deep Neck Flexor Activation Isolated Activation of Deep Cervical Neck Flexors Cobra with Cervical Retraction on Foam Roll: Bibliography:
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