Muscle specificity in tests of cervical flexor muscle performance

The effect of deep neck flexor endurance on craniovertebral angle changes and neck and shoulder muscle activities during a computer task

The deep neck flexors are important for maintaining neck posture by stabilizing and supporting it through low-intensity contraction, ensuring static endurance. The subjects performed computer tasks after having their deep neck flexor endurance measured using a pressure biofeedback unit. The craniovertebral angle (CVA) and the muscle activities were measured while participants were completing computer tasks for 10 min. The deep neck flexor endurance was significantly negatively correlated with CVA changes at 0-2 min. The deep neck flexor endurance was significantly negatively correlated with sternocleidomastoid muscle and upper trapezius activity at 0-2 min. The deep neck flexor endurance negatively predicted CVA changes at 0-2 min and explained 28.8% of the variance in the CVA changes. The lower the deep neck flexor endurance, the earlier the simultaneous changes occurred in the CVA and the neck and shoulder muscle activities during computer tasks.

A Novel Device for Assessment and Treatment of Upper Cervical Spine: Test-Retest Reliability Study

INTRODUCTION

Neck pain is one of the most frequent reasons for consultation in primary care. Clinicians evaluate different variables, including movement and cervical strength, to determine the prognosis of patients. Usually, the tools employed for this purpose are expensive and bulky, or more than one is needed. This study aims to describe a novel device designed to assess the cervical spine and describe its test-retest reliability.

METHODS

The Spinetrack device was designed to measure the strength of deep cervical flexor muscles and the chin-in and chin-out movement of the upper cervical spine. A test-retest reliability study was developed. The flexion, extension and strength needed to move the Spinetrack device were registered. Two measurements were developed, with one week between each assessment.

RESULTS

Twenty healthy subjects were evaluated. The strength of the deep cervical flexor muscles in the first measurement was 21.18 ± 3.15 Newtons, the displacement movement during chin-in movement was 12.79 mm ± 3.46 and the displacement during chin-out movement was 35.99 mm ± 4.44. The test-retest reliability of strength was ICC 0.97 (95% CI (0.91-0.99)).

CONCLUSION

The Spinetrack device has shown excellent test-retest reliability values for the measurement of the strength of the cervical flexor muscles and for the chin-in and chin-out movements.

Onset Timing of Hyoid Muscles Activation during Cervical Flexion Is Position-Dependent: An EMG Study

Due to the high prevalence of neck pain, considerable attention is paid to the function of cervical flexor muscles. Although the deep and superficial cervical flexor muscles have been evaluated, the impact of hyoid muscles on cervical flexion is still not well known. We, therefore, aimed to investigate the activation of hyoid muscles during physiological cervical flexion, and to determine the impact of different starting positions on cervical flexion muscle activation. The activities of bilateral sternocleidomastoid, scalene, suprahyoid, and infrahyoid muscles were evaluated by surface electromyography (EMG) in twenty young healthy volunteers. They performed a repetitive cervical flexion-extension movement, from neutral position of the head to the maximum flexion with the same speed set at eight seconds in a cycle, in three various positions (sitting, standing, and supine). In sitting and standing positions, the group of suprahyoid muscles was activated in advance of other cervical flexor muscles despite only significant differences were found in scalene muscles, and the activation of the group of infrahyoid muscles was time-synchronous with sternocleidomastoid muscles. On the other hand, in supine position, the activation of all measured cervical flexor muscles was significantly earlier and longer than in the other two positions. This study confirmed the empirical suggestion that hyoid muscles contributed to cervical flexion, and it confirmed that muscle activation was position dependent, even if the given movement is nearly identical.

Examining the Relationships Between Lingual Strength, Perihyoid Strength, and Swallowing Kinematics in Dysphagic Adults: A Retrospective Cross-Sectional Analysis

Purpose The aim of this study was to examine the relationships of clinical measures of lingual and perihyoid strength with displacement swallowing kinematics and swallowing safety in a heterogenous group of dysphagic adults. Method A retrospective analysis was completed of videofluoroscopic swallow studies of consecutive dysphagic outpatient adults presenting to a tertiary swallowing center from January 1, 2015, to December 31, 2017. Videofluoroscopic swallow study records were included if containing displacement swallowing kinematics of a 20-ml single liquid swallow and clinical measures of anterior (L-MIPA) or posterior (L-MIPP) lingual maximal isometric press, saliva mean swallowing pressures (S-MSP), and/or open mouth-maximal isometric press (OM-MIP). Regression analyses were used to examine the relationships between clinical measures of lingual (L-MIPA, L-MIPP, S-MSP) and perihyoid (OM-MIP) strength and displacement swallowing kinematics, and binomial logistic regressions were used to examine the relationships between clinical measures of lingual and perihyoid strength and swallowing safety (Penetration-Aspiration Scale [PAS]). Results Multivariate regressions revealed significant relationships of L-MIPA, L-MIPP, S-MSP, and OM-MIP with group-level changes to the displacement swallowing kinematics. Univariate analyses revealed significant relationships of L-MIPA and L-MIPP with pharyngeal constriction ratio, maximal extent of upper esophageal segment opening, and PAS. Conclusions Weak relationships were identified of clinical measures of lingual and perihyoid strength with displacement swallowing kinematics. These findings suggest that clinical measures of lingual and perihyoid strength do not fully explain impairments in swallowing kinematics across a heterogenous group of dysphagic patients. Weak-to-moderate relationships were identified between clinical measures of lingual strength and PAS, suggesting that they may have value in predicting functional measures of swallowing safety. Further research is needed to examine how findings may differ between specific patient populations.

Efficacy of Deep Cervical Flexor Muscle Training on Neck Pain, Functional Disability, and Muscle Endurance in School Teachers: A Clinical Trial

Background

Neck pain (NP) is a common work-related disorder, with high prevalence in the profession of teaching. The daily duties of a school teacher involve head-down postures while reading and writing, which expose them to the risk of developing NP. Deep cervical flexor (DCF) muscles have been reported to have lower endurance in patients with cervical impairment, which has additionally been associated with disability. There is limited evidence regarding the efficacy of training of DCF muscles in occupational NP. The objective of this study was to investigate the effects of DCF muscle training on pain, muscle endurance, and functional disability using pressure biofeedback in school teachers with NP.

Methods

Sixty-five teachers (age, 25-45 years) with more than 5 years of teaching experience participated in this study. They were randomly divided into two groups: the experimental (E) and control (C) groups. In the E group, the subjects underwent DCF muscle training using pressure biofeedback in addition to conventional exercises for neck pain, while those in the C group underwent conventional exercises only. Pain, muscle endurance, and disability were measured at day 0 (before the treatment) and days 14 and 42 after the treatment. Endurance of DCF muscles was measured by the craniocervical flexion test using pressure biofeedback, pain intensity was measured using the numeric pain rating scale, and functional disability was assessed using the neck disability index questionnaire. This study was performed in accordance with CONSORT guidelines.

Results

On day 0, there were no significant differences in the age, pain, muscle endurance, and disability levels between the groups. After initiating the intervention, although there were improvements in both groups, there was a statistically significant improvement in muscle endurance, pain, and disability in subjects who received additional training with pressure biofeedback.

Conclusions

Besides increasing muscle endurance, specific training of DCF muscles in addition to conventional exercises can improve neck pain and functional disability. These results should be further correlated clinically. A dedicated time for exercises at school could help prevent the development of NP in teachers. This trial is registered with ClinicalTrials.gov NCT03537300 May 24, 2018 (retrospectively registered).

The Importance of Optimal Gaze Direction on Deep Neck Flexor Activation in Chronic Neck Pain

Chronic neck pain (CNP) patients have weak deep neck flexors (DNF) and a hyperactive sternocleidomastoid (SCM). The cranio-cervical flexion test (CCFT) promotes activation of the DNF and decreases activity of the SCM, promoting pain recovery, but research suggests SCM activation increases with increasing gaze direction. We aimed to investigate how DNF and SCM activation varies according to gaze direction in the CCFT, and to prescribe the appropriate gaze direction for CNP. Twenty-eight CNP subjects had their maximum strength pressure level determined by CCFT for strength (20-~30 mmHg) and at each of the measured pressures, DNF and SCM thickness in each of four gaze directions (0°, 20°, 40°, and 60°) was measured by ultrasound imaging. The DNF to SCM ratio varied significantly according to gaze direction (p < 0.05), with gaze directions of 20° and 0° being significantly different from 40° (p < 0.05). Although there was no significant difference in DNF activation according to gaze direction, there was in SCM activation (p < 0.05), with SCM 60° significantly different from SCM 20° and SCM 40° (p < 0.05). In order to increase DNF activation efficiency during the CCFT, SCM activation should be controlled, and a gaze direction below 20° is the most efficient. This can inform DNF training of CNP patients in a clinical environment.

Comparative Strength and Endurance Parameters of the Craniocervical and Cervicothoracic Extensors and Flexors in Females With and Without Idiopathic Neck Pain

Isometric strength and endurance performance of cervical flexor and extensor muscles were compared in women with (n = 30) and without (n = 30) idiopathic neck pain at the craniocervical and cervicothoracic axes. Strength and endurance time (time to task failure in seconds) at 50% maximal voluntary contraction were recorded in 4 directions (craniocervical flexion/extension and cervicothoracic flexion/extension) and 6 strength and endurance ratios were calculated. Participants in both groups were matched for body mass index. The idiopathic neck pain group demonstrated significantly less strength for the cervicothoracic flexors and extensors (1.58-4.7 N·m [12.4%-17.9%] less, P < .04) and significantly less endurance time for the cervicothoracic and craniocervical flexors (10.77-10.9 s [23.3%-27.5%] less, P < .03). The cervicothoracic extension to craniocervical flexion strength ratio was also lower in the idiopathic neck pain group (P = .01); however, no other strength or endurance ratio was significantly different between groups. This exploratory study suggests assessing specific performance parameters accounting for regional muscular differences in the upper and lower neck is potentially informative to understanding impairments in neck pain conditions, particularly as impairments may not be uniform across muscle groups.

Open Mouth-Maximal Isometric Press: Development and Norms for Clinical Swallowing Evaluations and Treatment

Purpose The aims of this study were to (a) describe the development and utility of the Open Mouth-Maximal Isometric Press (OM-MIP), a tool designed for the quantitative assessment of suprahyoid-infrahyoid muscle strength; (b) examine the effects of age and sex on the OM-MIP; and (c) establish age- and sex-based OM-MIP norms. Method Two hundred sixteen healthy male and female volunteers were recruited. Participants performed the OM-MIP, and the maximum of 3 trials that were within 10% of each other was recorded. Rest between each trial was allowed to avoid fatigue. Multiple regression examined the influence of age and sex on the OM-MIP. Descriptive statistics outlined normative OM-MIP values for young adult (aged 18-39 years), middle-aged adult (aged 40-59 years), old adult (aged 60-79 years), and very old adult (aged ≥ 80 years) men and women. Two-way analysis of variance determined if normative data differed significantly between the age and sex groups. Results Age and sex significantly influenced the OM-MIP, although no significant interaction effect was identified. Women had lower mean OM-MIPs when compared with men ( p < .0005), and very old adults had lower mean OM-MIPs when compared with young ( p = .001), middle-aged ( p < .0005), and old ( p = .013) adults. Conclusions This study establishes age- and sex-based OM-MIP norms and outlines its potential utility during clinical swallowing evaluations and treatment. By providing these norms, clinicians can begin to quantitatively measure suprahyoid and infrahyoid strength, individualize resistance training programs to patients' OM-MIP 1 repetition maximum, and track strength changes over time in response to therapeutic interventions.

Temporomandibular disorder and comorbid neck pain: facts and hypotheses regarding pain-induced and rehabilitation-induced motor activity changes

According to the "pain adaptation model", temporomandibular disorder (TMD)-related pain induces a paradoxical activity of masticatory muscles: an agonistic hypoactivity during jaw closing and an antagonistic activity during jaw opening (agonist/antagonist co-activation). However, this model suffers several weaknesses; notably, it does not explain all types of neck muscle activities in neck pain (NP), which is a very prevalent TMD comorbid condition. In NP, neck muscle antagonistic activity is increased, and agonistic activity is decreased as postulated by the pain adaptation model. However, synergistic and compensatory activity may occur and agonistic activity may be unchanged or even increased as postulated within the "vicious cycle theory". Thus, both theories would apply partly as outlined currently in musculoskeletal disorders (MSD). Besides pain, psychological stress may also induce motor dysfunction in TMD and NP. In NP, rehabilitation may increase agonistic activity and decrease compensatory activity and antagonistic activity, thus inducing a switch from agonist/antagonist co-activation towards reciprocal inhibition. Thus, rehabilitation-induced motor activity changes constitute a new research field that should improve MSD therapeutics. Additionally, immature tongue function (so-called infantile swallow) might be connected to TMD where low agonistic activity of masticatory muscles would be compensated by facial muscle hyperactivity during oropharyngeal phase of deglutition.

Correlation between cervical flexor muscle thickness and craniocervical flexion torque in healthy subjects

The purpose of this study was to clarify the relationship between the size of the cervical flexor muscles and craniocervical (CC) flexion torque. Thirty-eight healthy men participated in this study. Thickness of the deep cervical flexor (DCF) and sternocleidomastoid (SM) muscles were measured using ultrasonography. Maximal isometric CC flexion torque was measured using dynamometry. The DCF and SM muscle thickness and CC flexion torque were normalized relative to body weight. Correlations between normalized muscle thickness and normalized CC flexion torque were determined. A significant positive correlation was observed between normalized DCF muscle thickness and normalized CC flexion torque (r = 0.361, P = 0.028), whereas there was no significant correlation between normalized SM muscle thickness and normalized CC flexion torque (r = 0.233, P = 0.166). DCF muscle thickness appears to have potential clinical application in the performance of CC flexion.

Group-based exercise at workplace: short-term effects of neck and shoulder resistance training in video display unit workers with work-related chronic neck pain-a pilot randomized trial

Effectiveness of exercise therapy in video display unit (VDU) workers with work-related chronic neck pain (W-RCNP) is unclear. The aim of the study was to assess the efficacy of group-based neck-shoulder resistance exercises on symptoms and muscular function in VDU workers with W-RCNP. Thirty-five employees with CNP were randomly assigned to neck-shoulder resistance exercise (NSRE) group or to conventional stretching and postural exercise (SPE) group. Participants trained 45 min, twice a week for 7 weeks. Primary outcomes were pain intensity (0-10 numeric rating scale, NRS) and pain-related disability (Vernon Neck Disability Index, NDI). Secondary outcomes were cervical active range of motion (AROM), endurance of neck flexors, strength of shoulder abductors, and health-related quality of life (SF-36). Post-treatment, pain and disability decreased 2.5 and 5 points in NSRE (p = 0.001) and 5 and 8 points in SPE (p = 0.002), with no significant differences between groups. AROM improved significantly in both groups; between-group differences were not significant. Neck flexors endurance and shoulder abductors strength improved by 59.6 and 34.2% (p = 0.001) in the NSRE group and by 27.6% (p = 0.009) and 2.3% (p = 0.002) in the SPE group; between-group differences were significant (p = 0.016 and p < 0.001, respectively). SF-36 score remained unchanged. NSRE and SPE are feasible and equally effective in reducing pain and pain-related disability as group exercises in W-RCNP. NSRE may provide some advantage in improving strength and endurance in neck muscles. Further, larger studies should confirm these findings and assess whether a better muscle function confers long-term clinical advantages.

Effectiveness of manual therapy for cervical radiculopathy, a review

Manual therapy is often used for patients with neck pain with or without radicular symptoms. There is sparse evidence on the effectiveness in cervical radiculopathy. The aim of this study was to assess current levels of evidence on the effectiveness of manual therapy interventions for patients with cervical radiculopathy. Electronic data bases were systematically searched for clinical guidelines, reviews and randomised clinical trials (RCTs) reporting on the effectiveness of manual therapy for patients with cervical radiculopathy. Eight relevant reviews, two guidelines and two recent RCTs, that had not yet been included in either, were retrieved. The overall quality of the evidence of included studies was evaluated using the GRADE method. Most interventions were only studied in one single RCT. There is low level evidence that cervical manipulation and mobilisation as unimodal interventions are effective on pain and range of motion at the immediate follow up, but no evidence on the effectiveness of thoracic manipulation or mobilisation as unimodal interventions. There is low level evidence that a combination of spinal mobilisation and motor control exercises is more effective on pain and activity limitations than separate interventions or a wait-and-see policy. There is low level evidence of the effectiveness of cervical mobilisation with a neurodynamical intent as unimodal intervention, on the effectiveness of a multimodal intervention with neurodynamic intent on pain activity limitations and global perceived effect compared to a wait-and-see policy. There is also low level evidence that a multimodal intervention consisting of spinal and neurodynamic mobilisations and specific exercises is effective on pain in patients with CR. There is low level evidence that traction is no more effective than placebo traction.

Cervico-ocular Reflex Is Increased in People With Nonspecific Neck Pain

BACKGROUND

Neck pain is a widespread complaint. People experiencing neck pain often present an altered timing in contraction of cervical muscles. This altered afferent information elicits the cervico-ocular reflex (COR), which stabilizes the eye in response to trunk-to-head movements. The vestibulo-ocular reflex (VOR) elicited by the vestibulum is thought to be unaffected by afferent information from the cervical spine.

OBJECTIVE

The aim of the study was to measure the COR and VOR in people with nonspecific neck pain.

DESIGN

This study utilized a cross-sectional design in accordance with the STROBE statement.

METHODS

An infrared eye-tracking device was used to record the COR and the VOR while the participant was sitting on a rotating chair in darkness. Eye velocity was calculated by taking the derivative of the horizontal eye position. Parametric statistics were performed.

RESULTS

The mean COR gain in the control group (n=30) was 0.26 (SD=0.15) compared with 0.38 (SD=0.16) in the nonspecific neck pain group (n=37). Analyses of covariance were performed to analyze differences in COR and VOR gains, with age and sex as covariates. Analyses of covariance showed a significantly increased COR in participants with neck pain. The VOR between the control group, with a mean VOR of 0.67 (SD=0.17), and the nonspecific neck pain group, with a mean VOR of 0.66 (SD=0.22), was not significantly different.

LIMITATIONS

Measuring eye movements while the participant is sitting on a rotating chair in complete darkness is technically complicated.

CONCLUSIONS

This study suggests that people with nonspecific neck pain have an increased COR. The COR is an objective, nonvoluntary eye reflex and an unaltered VOR. This study shows that an increased COR is not restricted to patients with traumatic neck pain.

Reliability of ultrasonography measurement for the longus colli according to inward probe pressure

[Purpose] To investigate the intra- and inter-rater reliability of the cross-sectional area (CSA) and muscle thickness (MT) of the longus colli according to the inward pressure of an ultrasonography (US) probe (0.5 and 1 kg). [Subjects] Thirteen subjects (11 males and 2 females; age, 23.1 ± 2.9 years) were recruited via convenience sampling of university students. [Methods] Real-time US measurements of the CSA and MT of the longus colli were recorded. Repeated US measurements using a standard protocol were performed on the same day 1 hour apart to assess intra- and inter-rater reliability. Intra-class correlation coefficients (ICC; 2, 1) were used to determine the intra- and inter-rater reliability of the CSA and MT measurements. [Results] This study demonstrated that the US measurements (0.5 and 1 kg) of the CSA and MT of the longus colli give reliable and consistent results. [Conclusion] Based on these results, a consistent inward pressure of the probe is needed to ensure precise US measurement of the longus colli muscle.

The Recline Exercise: Comparisons with the Head Lift Exercise in Healthy Adults

The aim of this investigation was to examine the comparative effectiveness of the new Recline Exercise (RE) and the traditional Head Lift Exercise (Shaker Exercise) on submental muscle activity, tongue strength, and perceived exertion in 40 healthy young adults (mean age = 24.5 years, SD 2.6 years). Both groups participated in a 6-week exercise regimen. Outcome variables evaluated pre- and post-exercise included: duration and peak amplitude of submental muscle activity during swallowing measured via surface electromyography (sEMG); anterior and posterior isometric lingual pressures measured with the Iowa Oral Performance Instrument; and perceived exertion levels measured with the Borg category-ratio scale of perceived exertion. Results indicated no significant pre-post differences within or between groups in swallow duration and peak amplitude. In addition, the RE group demonstrated significant post-treatment increases in anterior and posterior tongue strength [p = 0.009; p < 0.001]; however, these increases were of small magnitude (d = 0.132; d = 0.319). Both groups showed marked improvements in perceived exertion levels [p < 0.001]. Our findings indicate that healthy young adults who perform the RE or the HLE do not have significant swallow duration or amplitude gains, most likely due to the reduced need for such gains in the healthy head/neck musculature for submaximal tasks. Furthermore, the significant lingual strength gains seen with the RE indicate that additional musculature is being engaged during its completion. These results are encouraging; however, future research in older adults and patients with dysphagia with examination of swallowing biomechanics is needed to determine its full potential as a rehabilitative regimen.

An Exploratory Study to Determine the Relationship between Cervical Dysfunction and Perimenstrual Migraines

PURPOSE

To determine whether an association between cervical dysfunction and perimenstrual migraines exists.

METHODS

Forty perimenstrual migraine sufferers and 46 controls were compared. Information on the participants' ages and perceptions of neck pain and stiffness were solicited. The blinded physical examination of the cervical area consisted of postural, range of motion, muscle strength, muscle length, trigger point, neural mobility, and segmental cervical joint movement assessment.

RESULTS

The migraine group had increased perception of neck pain and stiffness (p<0.001); reduced bilateral rotation (p=0.013); decreased muscle length in both trapezii, left sternocleidomastoid, and right occipitals (p=0.045); more pain on muscle stretch in both levator scapulae, both trapezii, left sternocleidomastoid, and both occipitals (p=0.013); increased trigger points bilaterally in the left trapezius (p=0.021), right trapezius (p=0.023), left sternocleidomastoid (p=0.0.004), and right sternocleidomastoid (p=0.021); reduced neural mobility with bilateral elbow lag (p=0.043); greater C4-C6 pain (p=0.045); and increased cervical stiffness in C5-C7 (p=0.023). There were no differences in posture and muscle strength. Decreased muscle length increased the risk of perimenstrual migraines 2.4-6.7 fold, reduced neural mobility 5.8-10.7 fold, and increased C7 stiffness 17.0 fold.

CONCLUSION

The results suggest that an association between cervical dysfunction and perimenstrual headaches should be further explored.

Does Cervical Muscular Contraction Affect the Measurement for Electroglottographic Perturbation Parameters?

OBJECTIVES

The purpose was to assess whether cervical muscular contraction during phonation influences the period and amplitude perturbation quotients (PPQ and APQ, respectively) of electroglottographic (EGG) signals, and whether high-pass filtering can attenuate these effects.

STUDY DESIGN

Prospective.

METHODS

We included 19 nondysphonic speakers and 21 patients with muscle tension dysphonia. During the recording of acoustic and EGG signals, each participant was instructed to naturally phonate sustained vowels /i:/ and /a:/ (NP tasks), and additionally, each nondysphonic participant was asked to phonate the same vowels in a nondysphonic voice quality while contracting the cervical muscles (muscular contracted phonation [MCP] tasks). To confirm the contraction, surface and needle electromyography (EMG) was performed. The EGG signals were high-pass filtered at different cutoff frequencies from 0 to 90 Hz and were subsequently analyzed for the PPQ and APQ.

RESULTS

Compared with the NP tasks, the MCP tasks enhanced the cervical EMG activities ranging from 0 to more than 1000 Hz, but conferred only low-frequency noise to the EGG signals under 50 Hz and increased the values for EGG-APQ, but not EGG-PPQ. These EGG-APQ values exhibited gradual decreases after high-pass filtering with an increase in the cutoff frequency ranging from 0 to 50 Hz in both groups, followed by plateaus during the MCP tasks in the nondysphonic group.

CONCLUSIONS

The present results demonstrate that cervical muscular contraction seriously affects the EGG-APQ values for unfiltered EGG signals independent of the EMG activities and that appropriate high-pass filtering over 50 Hz can attenuate these effects.

Longitudinal changes in ventral and dorsal neck muscle layers during loading against gravity in healthy volunteers using speckle tracking

OBJECTIVE

This study aimed to describe and compare the longitudinal mechanical activity, deformation, and deformation rate of the different layers of dorsal and ventral neck muscles in healthy volunteers during head lifts against gravity.

METHODS

The cross-sectional study included 19 healthy volunteers (mean age, 28 years; SD, 7 years). Ultrasound with speckle-tracking analysis was used to investigate longitudinal mechanical activation, deformation, and deformation rate of dorsal and ventral neck muscles in real time during a head lift. Significance levels were set as P = .025 or P = .0125, depending on the number of comparisons.

RESULTS

The dorsal neck muscles did not significantly differ in deformation (P > .04); however, the multifidus had a higher deformation rate than all other dorsal muscles (P < .003). The sternocleidomastoid had significantly higher deformation than the longus capitis (P = .005) and colli (P = .001) but a lower deformation rate than the longus colli (P = .02).

CONCLUSION

The sternocleidomastoid deformed more than the deeper muscles, but it did significantly slower than the longus colli. Among the dorsal muscles, the deepest (the multifidus) had the highest deformation rate.

The effect of training the deep cervical flexors on neck pain, neck mobility, and dizziness in a patient with chronic nonspecific neck pain after prolonged bed rest: a case report

STUDY DESIGN

Case report.

BACKGROUND

Immobilization and chronic neck pain may cause a transformation of muscle tissue fibers. These changes affect the ability to effectively control 3-D movement of the cervical spine. This case report describes the effect of specific deep cervical flexor (DCF) musculature training in a patient with chronic neck pain and dizziness.

CASE DESCRIPTION

A 19-year-old woman presented with a 24-month history of neck pain and dizziness. Symptoms started during a 2-month immobilization period while in the intensive care unit for the treatment of brainstem encephalitis. Outcome measures included pain level, limitations in activities, fear avoidance, range of motion, dizziness, and function of the DCFs. Treatment was aimed at restoring altered motor control of the neck muscles using DCF training integrated with functional activities for 10 treatment sessions over 12 weeks.

OUTCOMES

At the time of discharge, the patient reported full recovery and no restriction in her daily activities. Her score on the Neck Disability Index had improved by 28 points, active range of motion had increased, and her symptoms of dizziness were resolved. These results were maintained at 6-month follow-up.

DISCUSSION

This patient responded positively to DCF training, resulting in an increase in cervical spine range of motion and a reduction of dizziness, pain, and limitations in activities.

Ultrasound imaging with speckle tracking of cervical muscle deformation and deformation rate: isometric contraction of patients after anterior cervical decompression and fusion for cervical disc disease and controls

There is currently a lack of information regarding neck muscle activity during specific exercises. The purpose of the present study was to investigate deformation and deformation rate in different layers of dorsal and ventral neck muscles during isometric neck muscle contraction in individuals after anterior cervical decompression and fusion and in healthy controls. This study included 10 individuals (mean age 60 years; SD 7.1) with a verified, long-standing neck disorder and 10 healthy, age- and sex-matched controls. Ultrasonography and post-process speckle tracking analysis was used to investigate the degree and the rate of neck muscles motions at the C4 segmental level during sub-maximal, isometric resistance of the head in a seated position. None of the analyses performed showed significant differences between groups (p > 0.05). In the dorsal muscles, both groups exhibited a higher deformation rate in the multifidus than in the trapezius, splenius, and semispinalis capitis (p ≤ 0.01). In the neck disorder group, the multifidus also showed a higher deformation rate compared to the semispinalis cervicis (p = 0.02). In the ventral muscles of patients with neck disorders, the longus colli had a higher deformation rate than the sternocleidomastoid (p = 0.02). Among the healthy controls, the multifidus showed a higher degree of deformation (p = 0.02) than the trapezius. In conclusion, our results showed no significant differences between the two groups in mechanical neck muscle activation. Larger studies with different exercises, preferably with a standardized measure of resistance, are needed to investigate whether patients and controls show differences in deformation and deformation rates in neck muscles.

The craniocervical flexion test: an investigation of performance in young asymptomatic subjects

INTRODUCTION

The Deep Cervical Flexors (DCFs) provide support and segmental stability to the cervical spine. However, their endurance capacity can be reduced in cervicogenic disorders. The Craniocervical Flexion Test (CCFT) is regarded as the most effective means of assessing the contractile performance of these muscles. However, limited normative data exists to serve as a reference point during diagnosis.

AIM

This study examined CCFT performance in a group of young asymptomatic subjects and investigated the influence of physical activity levels, age and gender on CCFT score.

METHOD

The most recent CCFT protocol as described by Jull et al. (2008) was used. Baseline assessment scores along with certain patient characteristics were recorded on one occasion.

RESULTS

For testing, 34 asymptomatic subjects were recruited (24 females, 10 males with a mean age of 21.5 ± 2.15 years). The median baseline assessment score was 24 mmHg (interquartile range = 3). Physical activity levels, age or gender did not significantly correlate with DNF endurance (P > 0.05).

CONCLUSION

The Median Baseline Assessment score was 24 mmHg (interquartile range = 3). Between-subject variability was high while physical activity levels; age or gender did not appear to influence the DCF muscle tonic holding capacity. The small heterogeneous sample involved in this study highlights the need for high quality normative studies to validate these findings.

CERVICAL ELECTROMYOGRAPHIC ACTIVITIES DURING NECK MOVEMENTS AT DIFFERENT SPEEDS IN HEALTHY SUBJECTS: VOLUNTARY RESPONSE INDEX ANALYSIS

The assessment of cervical muscle control patterns is important for the diagnosis of cervical dysfunction. Voluntary response index (VRI), including the similarity index (SI) and the magnitude (MAG), provides quantitative analysis of the surface electromyography (sEMG) pattern and total muscle voluntary activities respectively. This study was to investigate the effect of movement directions and speeds of the VRI response of cervical muscles in healthy subjects. The sEMG of bilateral sternocleidomastoid, semispinalis capitis, and splenius capitis were measured in thirteen asymptomatic young subjects. The subjects performed voluntary neck movements in flexion, extension, left and right side bending at fast, medium, and slow speeds. The results showed that SI ranged from 1–0.8 and MAG was generally less than 40 μV. The SI was significantly smallest and the MAG was largest at fast speed. The MAG was also significantly different among directions but the effect of direction on SI was only significant at fast speed. In conclusion, the movement speed and direction could affect the magnitude and control pattern of cervical muscles, such that both the speed and direction of the examined tasks should be carefully monitored during the assessment of cervical muscle activation.

Training mode-dependent changes in motor performance in neck pain

OBJECTIVE

To determine whether changes in motor performance after a course of exercise in patients with mechanical neck pain (MNP) were dependent on the primary behavioral demand of the exercise performed.

DESIGN

Randomized controlled trial.

SETTING

University laboratory.

PARTICIPANTS

Volunteers (N=60; 35 women, 25 men; mean age, 37.9y) with chronic MNP participated in the study.

INTERVENTION

Exercise targeted to improve cervical motor performance including endurance training (ETr; n=20), coordination training (CTr; n=20), and active mobility training (n=20).

MAIN OUTCOME MEASURES

Changes in the cervical motor performance domains of strength, endurance, coordination, and active mobility were evaluated immediately after the 10-week training program, and at a 26-week follow-up.

RESULTS

Between-group comparisons revealed significantly greater gains in endurance (P<.02) by the ETr group, and significantly greater gains in coordination (P<.01) by the CTr group. All 3 groups had improvement in pain (P<.01) and disability (P<.01).

CONCLUSIONS

Changes in motor performance in individuals with MNP in response to an exercise program were dependent on the specific mode of exercise performed, with minimal improvement in other domains of motor performance.

Ultrasonographic analysis of the neck flexor muscles in patients with chronic neck pain and changes after cervical spine mobilization

OBJECTIVE

The purpose of this study was to analyze changes in the recruitment of the muscles longus colli (Lco) and sternocledomastoid (SCM) as measured by ultrasonography in patients with chronic neck pain before and immediately after a single cervical Maitland's posterior-anterior central mobilization technique.

METHODS

This was a cross-sectional, case-control research design study. Ultrasonographic images of Lco and SCM were taken in 31 patients with chronic neck pain and matched controls during the 5 phases of the craniocervical flexion test before and after a Maitland's posterior-anterior central mobilization session at the cervical spine. Changes in muscle thickness during the test were calculated to infer muscle recruitment. Separate analysis of variance models for each muscle was built.

RESULTS

Both groups showed increases in Lco and SCM recruitment between phases (F = 7.95, P < .001; F = 21.29, P < .001), with patients with chronic neck pain demonstrating lesser increases for Lco changes in thickness compared with controls, mainly at phase 5 (-0.09, P = .004; 95% confidence interval [CI], 0.03-0.15). After the mobilization, Lco recruitment increased more significantly in patients with chronic neck pain, and previous difference between groups in phase 5 was no longer significant (-0.07, P = .07; 95% CI, -0.14 to 0.01). The SCM recruitment decreased in phase 1 for patients with chronic neck pain (P = .01; 95% CI, -0.06 to -0.01).

CONCLUSION

Cervical mobilization appeared to modulate neck muscles function by increasing deep muscle and reducing superficial muscles recruitment.

Muscle functional MRI as an imaging tool to evaluate muscle activity

Muscle functional magnetic resonance imaging (mfMRI) is an innovative technique that offers a noninvasive method to quantify changes in muscle physiology following the performance of exercise. The mfMRI technique is based on signal intensity changes due to increases in the relaxation time of tissue water. In contemporary practice, mfMRI has proven to be an excellent tool for assessing the extent of muscle activation following the performance of a task and for the evaluation of neuromuscular adaptations as a result of therapeutic interventions. This article focuses on the underlying mechanisms and methods of mfMRI, discusses the validity and advantages of the method, and provides an overview of studies in which mfMRI is used to evaluate the effect of exercise and exercise training on muscle activity in both experimental and clinical studies.

The craniocervical flexion test: intra-tester reliability in asymptomatic subjects

BACKGROUND AND PURPOSE

The deep neck flexor muscles (DNFs) stabilize the cervical spine and cervicogenic pain appears to adversely affect their endurance capacity. They are inaccessible to direct palpation, thereby making assessment difficult. However, the cranio-cervical flexion test (CCFT) provides an indirect method of assessing the endurance capacity of the DNFs. The purpose of the present study was to evaluate the intratester reliability of the CCFT in asymptomatic subjects.

METHOD

The clinical protocol of the CCFT was measured on two occasions with 7 days between measurements. Prior to testing, participants were trained and compensation strategies were corrected. Nineteen asymptomatic participants (mean age 24.9 years; range 22-36) were recruited.

RESULTS

The test had excellent intratester reliability (intraclass correlation coefficient = 0.983; standard error of the mean = 8.94; smallest real difference = 24.7). A Bland and Altman's limits of agreement analysis confirmed the high reliability of the test.

CONCLUSION

The CCFT results demonstrated excellent intra-tester reliability in asymptomatic subjects, thus contributing to the normative data regarding the test.

A magnetic resonance imaging investigation into the function of the deep cervical flexors during the performance of craniocervical flexion

OBJECTIVE

Evidence suggests that the deep cervical flexors (DCFs) are important for the control of the cervical spine. The craniocervical flexion (CCF) test is a clinical test developed for patients with neck pain disorders based on the action of the DCFs. Because these muscles are deeply situated, it is difficult to reach the DCFs with surface electromyography. Magnetic resonance imaging (MRI) can be used to measure these muscles in cross section. The objective of this study was (1) to determine the reliability of MRI for measuring cross-sectional area (CSA) of the longus colli (Lco) and longus capitis (Lca) and (2) to evaluate the changes in CSA during contraction.

METHODS

Thirty healthy subjects aged 29 +/- 9.3 years were imaged using MRI. The CSA of the Lco and Lca was evaluated at 4 different levels (C0-C1, C2-C3, C4-C5, and C6-C7) at rest and during CCF.

RESULTS

The intraclass correlation coefficients for the CSA of the Lco and Lca showed good to excellent reliability (0.73-0.92), except at the C4-C5 level. There was a significant increase in CSA of both Lco (F = 6.79, P = .015) and Lca (F = 19.20, P <or= .001) due to CCF, and this was at different levels. The highest increases in CSA occurred at the C0-C1 level for the Lca (11.1%) and at the C2-C3 level for the Lco (17.4%).

CONCLUSIONS

This study demonstrated that the action of CCF resulted in a contraction of the Lco and Lca at different levels. The results indicate that MRI is a promising technique to evaluate changes in CSA during contraction.

A Comparison of Craniocervical and Cervicothoracic Muscle Strength in Healthy Individuals

The purpose of this study was to compare maximal torque exerted about the craniocervical (CC) and cervicothoracic (CT) axes in the sagittal plane using a novel dynamometry device. Maximal voluntary contraction (MVC) recordings in newton-meters (N·m) were measured in 20 males and 20 females for each of 4 tests: CT extension, CT flexion, CC extension, CC flexion. Twenty of the volunteers repeated the testing procedure on a second occasion to determine the test–retest repeatability of the measures. MVC recordings at the CT axis (extension, 30.24 ± 12.15 N·m; flexion, 18.90 ± 8.21 N⋅m) were 1.4–2 times greater than recordings at the CC axis (extension, 16.46 ± 7.26 N⋅m; fexion, 13.34 ± 5.97 N·m). Extensor to flexor strength ratios reduced from 1.75 at the CT axis to 1.24 at the CC axis, but were similar for both males and females. Good to excellent test–retest repeatability was demonstrated for all tests (ICC = 0.75–0.99,SEM= 0.50–2.44 N·m). Consistent with differences in the muscle morphology at the CC and CT axes, torque exerted about these axes differ. Separate measurement of torque about these axes potentially offers a more comprehensive profile of cervical muscle strength.

The assessment of the cervical spine. Part 2: strength and endurance/fatigue

Quantitative documentation of physical deficits such as muscle strength and endurance/fatigue in the cervical spine may provide objective information, not only helping the diagnostic procedures, but also monitoring rehabilitation progress and documenting permanent impairments. The reliable and valid evaluation of muscle strength and endurance both in clinical and research environments are a difficult task since there are many factors that could affect the assessment procedure and the obtained values. The aim of the second part of this critical review is to identify the factors influencing the assessment of strength and endurance/fatigue of the muscles in the cervical spine.

Use of muscle functional magnetic resonance imaging to compare cervical flexor activity between patients with whiplash-associated disorders and people who are healthy

BACKGROUND

Chronic whiplash-associated disorders (WAD) have been shown to be associated with motor dysfunction. Increased electromyographic (EMG) activity in neck and shoulder girdle muscles has been demonstrated during different tasks in participants with persistent WAD. Muscle functional magnetic resonance imaging (mfMRI) is an innovative technique to evaluate muscle activity and differential recruitment of deep and superficial muscles following exercise.

OBJECTIVE

The purpose of this study was to compare the recruitment pattern of deep and superficial neck flexors between patients with WAD and controls using mfMRI.

DESIGN

A cross-sectional design was used.

METHOD

The study was conducted in a physical and rehabilitation medicine department. The participants were 19 controls who were healthy (10 men, 9 women; mean [+/-SD] age=22.2+/-0.6 years) and 16 patients with WAD (5 men, 11 women; mean [+/-SD] age=32.9+/-12.7 years). The T2 values were calculated for the longus colli (Lco), longus capitis (Lca), and sternocleidomastoid (SCM) muscles at rest and following cranio-cervical flexion (CCF).

RESULTS

In the overall statistical model for T2 shift, there was a significant main effect for muscle (F=3.906, P=.033) but not for group (F=2.855, P=.101). The muscle x group interaction effect was significant (F=3.618, P=.041). Although not significant, there was a strong trend for lesser Lco (P=.061) and Lca (P=.060) activity for the WAD group compared with the control group. Although the SCM showed higher T2 shifts, this difference was not significant (P=.291).

LIMITATIONS

Although mfMRI is an innovative and useful technique for the evaluation of deep cervical muscles, consideration is required, as this method encompasses a postexercise evaluation and is limited to resistance types of exercises.

CONCLUSIONS

Muscle functional magnetic resonance imaging demonstrated a difference in muscle recruitment between the Lco, Lca, and SCM during CCF in the control group, but failed to demonstrate a changed activity pattern in the WAD group compared with the control group. The mild symptoms in the WAD group and the wide variability in T2 values may explain the lack of significance.

Integration of the reflex pharyngeal swallow into rhythmic oral activity in a neurologically intact pig model

Mammalian swallowing involves the coordinated and sequential activity of many oropharyngeal muscles. Using synchronous electromyography (EMG) and videofluorography, we recorded the pattern of EMG activity for 12 muscles during swallowing in neurologically intact suckling pigs. We tested the hypothesis that this EMG pattern corresponded to the established pattern of activity for the isolated, reflexive pharyngeal swallow of the decerebrate infant pig. The EMG activity associated with the normal swallow of the intact animal had two components: a staggered pattern of single EMG bursts that were prominent in the stylohyoid, thyrohyoid, cricothyroid, and omohyoid muscles and double bursts of activity in some muscles, including geniohyoid and genioglossus, with the same underlying periodicity as suckling. Most of the staggered activity pattern, a linear sequence of progressively delayed activities in different muscles, was not statistically different from that previously found in the reflexive pharyngeal swallow of the decerebrate. However, not all components of the linear sequence of the reflexive swallow were inserted unchanged into the intact swallow. Some components appeared to be delayed or advanced, bringing them into phase with the underlying rhythmic activity. The difference between swallows of intact and of decerebrate animals was not solely due to the presence of rhythmic activity in the former. The timing of some EMG activities in intact animals also differed from the same activities in the few decerebrates that exhibited rhythmic tongue and jaw activity. These results suggest cerebral function influences the EMG pattern of the pharyngeal swallow, which has traditionally been considered a purely reflex pattern.

Muscle dysfunction in cervical spine pain: implications for assessment and management

SYNOPSIS

There is irrefutable evidence of an association between mechanical neck pain (MNP) and dysfunction of the muscles of the cervical spine. A myriad of impairments have been demonstrated that include changes in the physical structure (cross-sectional area, fatty infiltration, fiber type), as well as changes in behavior (timing and activation level), of the cervical muscles. Such changes suggest an impaired capacity of the cervical muscles to generate, sustain, and maintain precision of the required levels of torque needed for optimal function. In the context of physical support, these changes potentially have deleterious consequences for the cervical region, which relies heavily on its muscles for mechanical stability. While interventions focused on the retraining of cervical muscle function have shown favorable responses in alleviating MNP, the development of best practice strategies for the assessment and management of cervical muscle dysfunction is still a work in progress. One obstacle in researching the efficacy of cervical muscle training is that, as yet, we do not possess the capacity to optimally measure and classify those patients most likely to respond to different methods of training that would enrich clinical practice. While gains in this area are emerging, the ability of a clinician to best identify the need and implement the most appropriate method of training cervical muscle function is still largely dependent on a comprehensive examination of the patient that considers all aspects of the patient's disorder and functional requirements.

LEVEL OF EVIDENCE

Level 5.

Clinical assessment of the deep cervical flexor muscles: the craniocervical flexion test

BACKGROUND

The craniocervical flexion test (CCFT) is a clinical test of the anatomical action of the deep cervical flexor muscles, the longus capitis, and colli. It has evolved over 15 years as both a clinical and research tool and was devised in response to research indicating the importance of the deep cervical flexors in support of the cervical lordosis and motion segments and clinical observations of their impairment with neck pain.

SPECIAL FEATURES

The CCFT could be described as a test of neuromotor control. The features assessed are the activation and isometric endurance of the deep cervical flexors as well as their interaction with the superficial cervical flexors during the performance of five progressive stages of increasing craniocervical flexion range of motion. It is a low-load test performed in the supine position with the patient guided to each stage by feedback from a pressure sensor placed behind the neck. While the test in the clinical setting provides only an indirect measure of performance, the construct validity of the CCFT has been verified in a laboratory setting by direct measurement of deep and superficial flexor muscle activity.

SUMMARY

Research has established that patients with neck pain disorders, compared to controls, have an altered neuromotor control strategy during craniocervical flexion characterized by reduced activity in the deep cervical flexors and increased activity in the superficial flexors usually accompanied by altered movement strategies. Furthermore, they display reduced isometric endurance of the deep cervical flexor muscles. The muscle impairment identified with the CCFT appears to be generic to neck pain disorders of various etiologies. These observations prompted the use of the craniocervical flexion action for retraining the deep cervical flexor muscles within a motor relearning program for neck pain patients, which has shown positive therapeutic benefits when tested in clinical trials.

Clinimetric evaluation of methods to measure muscle functioning in patients with non-specific neck pain: a systematic review

Background

Neck pain is a significant health problem in modern society. There is evidence to suggest that neck muscle strength is reduced in patients with neck pain. This article provides a critical analysis of the research literature on the clinimetric properties of tests to measure neck muscle strength or endurance in patients with non-specific neck pain, which can be used in daily practice.

Methods

A computerised literature search was performed in the Medline, CINAHL and Embase databases from 1980 to January 2007. Two reviewers independently assessed the clinimetric properties of identified measurement methods, using a checklist of generally accepted criteria for reproducibility (inter- and intra-observer reliability and agreement), construct validity, responsiveness and feasibility.

Results

The search identified a total of 16 studies. The instruments or tests included were: muscle endurance tests for short neck flexors, craniocervical flexion test with an inflatable pressure biofeedback unit, manual muscle testing of neck musculature, dynamometry and functional lifting tests (the cervical progressive iso-inertial lifting evaluation (PILE) test and the timed weighted overhead test). All the articles included report information on the reproducibility of the tests. Acceptable intra- and inter-observer reliability was demonstrated for t enduranctest for short neck flexors and the cervical PILE test. Construct validity and responsiveness have hardly been documented for tests on muscle functioning.

Conclusion

The endurance test of the short neck flexors and the cervical PILE test can be regarded as appropriate instruments for measuring different aspects of neck muscle function in patients with non-specific neck pain. Common methodological flaws in the studies were their small sample size and an inappropriate description of the study design.

The use of functional MRI to evaluate cervical flexor activity during different cervical flexion exercises

The purpose of this study was to investigate the recruitment pattern of deep and superficial neck flexors evoked by three different cervical flexion exercises using muscle functional MRI. In 19 healthy participants, transverse relaxation time (T2) values were calculated for the longus colli (Lco), longus capitis (Lca), and sternocleidomastoid (SCM) at rest and following three exercises: conventional cervical flexion (CF), craniocervical flexion (CCF), and a combined craniocervical flexion and cervical flexion (CCF-CF). CCF-CF gave the highest T2 increase for all muscles. CCF displayed a significantly higher T2 increase for the Lca compared with the Lco and the SCM. When comparing the CCF and CF, no significant difference was found for the Lca, whereas the Lco and SCM displayed a higher T2 increase during CF compared with CCF. This study shows that muscle functional MRI can be used to characterize the specific activation levels and recruitment patterns of the superficial and deep neck flexors during different cervical flexion exercises. During CCF-CF, all synergists are maximally recruited, which makes this exercise useful for high-load training. CCF may provide a more specific method to assess and retrain Lca muscle performance compared with CF and CCF-CF. This study highlights the need to differentiate between the Lco and Lca when evaluating their function, since these results demonstrate a clear difference in activation of both muscles.

Specific Therapeutic Exercise of the Neck Induces Immediate Local Hypoalgesia

This study compared the effect of 2 specific cervical flexor muscle exercise protocols on immediate pain relief in the cervical spine of people with chronic neck pain. In addition, the study evaluated whether these exercise protocols elicited any systemic effects by studying sympathetic nervous system (SNS) function and pain at a location distant from the cervical spine. Participants were randomly allocated into either a cranio-cervical flexion (CCF) coordination exercise group (n = 24) or a cervical flexion (CF) endurance exercise group (n = 24). Measures of pain and SNS function were recorded immediately before and after a single session of the exercise interventions. Pain measures included visual analogue scale (VAS) ratings of neck pain at rest and during active cervical motion and pressure pain threshold (PPT) and thermal pain threshold (TPT) recordings over the cervical spine and at a remote site on the leg. Measures of SNS function consisted of blood flow, skin conductance, skin temperature, heart rate, and blood pressure. Immediately after 1 session of exercise, there was a reasonably sized increase of 21% (P < .001, d = 0.88) and 7.3% (P = .03, d = 0.47) in PPT locally at the neck for the CCF exercise and the CF exercise, respectively. There were no changes in local neck TPT with either exercise. Pressure pain threshold and TPT at the leg and SNS did not change after exercise. Only the CCF exercise demonstrated a small improvement in VAS ratings during active movement (change on 10-cm VAS: CCF, 0.42 cm (P = .04). This study shows that specific CCF therapeutic exercise is likely to provide immediate change in mechanical hyperalgesia local to the neck with translation into perceived pain relief on movement in patients with chronic neck pain.

PERSPECTIVE

This study showed an immediate local mechanical hypoalgesic response to specific exercise of the cervical spine. Understanding the pain-relieving effects of exercise will assist the clinician in prescribing the most appropriate exercise protocols for patients with chronic neck pain.

The influence of breathing type, expiration and cervical posture on the performance of the cranio-cervical flexion test in healthy subjects

The cranio-cervical flexion test (CCF-T) is used as a clinical evaluation tool for the deep cervical flexors (DCF). The influence of breathing type, expiration and cervical posture on the performance of the test is evaluated in asymptomatic subjects. Thirty volunteers participated in the study and were classified according to their breathing type: costo-diaphragmatic breathing type and upper costal breathing type. Sternocleidomastoid (SCM) electromyographic (EMG) activity was recorded during five incremental levels of CCF during normal breathing as well as during expiration. The cranio-vertebral angle of each subject was measured to quantify cervical posture. During normal inspiration, higher EMG activity of the SCM muscles was observed in subjects with an upper costal breathing pattern compared to costo-diaphragmatic breathing subjects. This difference was statistically significant (P< 0.05) at the three lowest stages of the test. In the upper costal breathing group a significantly lower EMG activity of the SCM muscles was observed while performing the CCF-T during slow expiration compared to normal breathing. No significant correlation was found between the cranio-vertebral angle and the EMG activity of the SCM muscles. Performing the CCF-T during slow expiration diminishes the activity of the SCM muscles in subjects with a predominantly upper costal breathing pattern. Using a costo-diaphragmatic breathing pattern while performing the test will optimize the performance. Studies on neck pain patients are required to further clarify this issue.