Current Pain and Fear of Pain Contribute to Reduced Maximum Voluntary Contraction of Neck Muscles in Patients With Chronic Neck Pain

Effect of physical activity education on shoulder girdle pain and muscle strength in participants with fibromyalgia: a pilot experimental study

Background

In patients with fibromyalgia, exercise and education are recommended to decrease pain level and improve pain management. The latest scientific evidence recommends to focus interventions on the upper limb. The aim of this pilot study was to compare the immediate effect of physical activity education vs. a control group on pain and muscle capacity in fibromyalgia patients.

Method

Fifty-six participants with fibromyalgia were randomized into an experimental group and a control group. The intervention consisted in watching a five-minute video that provided information about fibromyalgia, pain, kinesiophobia and physical activity. The control group watched a neutral five-minute video about beavers in Quebec. Following the video, participants performed a muscular fatigue task consisting of a repeated unilateral shoulder abduction task. At baseline and following the muscular fatigue task, maximal voluntary contraction (MVC) in shoulder abduction was assessed as well as pain level and pressure pain threshold (PPT) in the upper limb. Electromyographic activity was also assessed for upper trapezius and middle deltoid muscles. Two-way repeated measures analysis of variance was used to compare the MVC, PPT, and pain level before and after the muscular fatigue task between groups.

Results

The experimental group showed a significantly lower increase in pain than the control group in the middle deltoid muscle (p = 0.002) when assessed by verbal pain rating scale. No significant interaction or main effect of Group and Time were observed for the pain level at the upper trapezius and elbow extensor muscles nor for any of the PPT measures. According to electromyographic data, the median frequency values indicate that neither group experienced muscle fatigue during the repeated contraction task.

Conclusions

The preliminary results suggest that a short physical activity education video positively influenced middle deltoid pain following repeated abduction in participants with fibromyalgia. Electromyographic analysis showed no evidence of objective muscle fatigue, suggesting that there might be a partial disconnection between the perception of muscle fatigue and the physiological biomarkers associated with muscle fatigue.

Efficacy of telerehabilitation exercise in patients with chronic neck pain: a protocol for a non-inferiority randomized controlled trial

The aim of this study is to investigate if telerehabilitation is just as effective as the same face-to-face exercise program in patients with chronic neck pain (NP). 140 participants will participate in this non-inferiority randomized controlled trial. Primary outcomes will be pain intensity and disability, and secondary outcomes will be kinesiophobia, catastrophizing, fear avoidance beliefs, anxiety and depression symptoms, self-efficacy for pain and global perceived effect. It will be collected at baseline, 6 weeks and 6 months after intervention. The analysis of non-inferiority will be calculated by mixed linear models considering the non-inferiority margin. The results of this clinical trial will be able to overcome the barriers that physiotherapists face for the success of their therapies. In addition, it may reduce the high demands and public health costs with NP. Brazilian Clinical Trials Registry (RBR-6VBSMB). Clinical Trial Registration: REBEC (Brazilian Registry of Clinical Trials) RBR-6VBSMB (ClinicalTrials.gov).

Deficits in neuromuscular control of increasing force in patients with chronic lateral epicondylitis

Objective: This study investigated the neuromuscular control of increasing and releasing force in patients with chronic lateral epicondylitis (CLE). Methods: Fifteen patients with CLE (10 males, 5 females, 46.5 ± 6.3 years) and fifteen healthy participants (9 males, 6 females, 45.3 ± 2.5 years) participated in this study. In addition to power grip and maximal voluntary contraction (MVC) of wrist extension, force fluctuation dynamics and characteristics of inter-spike intervals (ISI) of motor units (MUs) with various recruitment thresholds in the extensor carpi radialis brevis (ECRB) and extensor carpi radialis longus (ECRL) during a designated force-tracking task with a trapezoidal target (0%-75%-0% MVC) were assessed. Results: Besides a smaller MVC of wrist extension, the patients exhibited significantly greater task errors (p = 0.007) and force fluctuations (p = 0.001) during force increment than the healthy counterparts. Nevertheless, no force variables significantly differed between groups during force release (p > 0.05). During force increment, the amplitudes of the motor unit action potential of the ECRB and ECRL muscles of the patients were smaller than those of the heathy counterparts (p < 0.001). The patient group also exhibited a higher percentage of motor units (MU) with lower recruitment threshold (<5% MVC) in the ECRL/ECRB muscles and a lower percentage of MU with higher recruitment threshold (>40% MVC) in the ECRB muscle, compared to the healthy group. During force increment, the patient group exhibited a higher rate of decrease in inter-spike intervals (ISIs) of motor units with lower recruitment thresholds (<10% MVC) in the ECRB and ECRL muscles, compared to the control group (p < 0.005). Conclusion: The patients with CLE exhibited more pronounced impairment in increasing force than in releasing force. This impairment in increasing force is attributed to deficits in tendon structure and degenerative changes in the larger motor units of the wrist extensors. To compensate for the neuromuscular deficits, the rate of progressive increase in discharge rate of the remaining smaller motor units (MUs) is enhanced to generate force. Significance: The deficits in neuromuscular control observed in CLE with degenerative changes cannot be fully explained by the experimental pain model, which predicts pain-related inhibition on low-threshold motor units.

Assessment of pain, scapulothoracic muscle strength, endurance and scapular dyskinesis in individuals with and without nonspecific chronic neck pain: A cross-sectional study

INTRODUCTION

This study is aimed to evaluate pain, muscle strength, scapular muscular endurance and scapular kinesis in individuals with Nonspecific Chronic Neck Pain and to compare them with asymptomatic individuals. In addition, to investigate the effect of mechanical changes in the scapular region on neck pain.

METHOD

40 individuals who applied to Kırıkkale University Faculty of Medicine Hospital Physical Therapy and Rehabilitation Center and diagnosed with NSCNP and 40 asymptomatic individuals for the control group were included the study. Pain was evaluated with Visual Analogue Scale, pain threshold and pain tolerance with algometer, cervical deep flexor group muscle strength with Stabilizer Pressure Biofeedback device, and neck and scapulothoracic muscle strength with Hand Held Dynamometer. Scapular Dyskinesia Test, Scapular Depression Test and Lateral Scapular Slide Test were used to evaluate scapular kinesis. A timer was used to evaluate scapular muscular endurance.

RESULT

Pain threshold and pain tolerance values of the NSCNP group were lower (p < 0.05). Muscle strength around neck and scapulothoracic region of the NSCNP group were lower than the asymptomatic individuals (p < 0.05). NSCNP group had more scapular dyskinesia (p < 0.05). Scapular muscular endurance values of the NSCNP group were lower (p < 0.05).

CONCLUSION

As a result, pain threshold and pain tolerance decreased, muscle strength of the neck region and the scapular region decreased, scapular endurance values decreased and the incidence of scapular dyskinesia increased in the individuals with NSCNP compared to the asymptomatic individuals. It is thought that our study will provide a different perspective in the evaluation of neck pain and including the scapular region to the evaluations.

Potential Use of Wearable Inertial Sensors to Assess and Train Deep Cervical Flexors: A Feasibility Study with Real Time Synchronization of Kinematic and Pressure Data during the Craniocervical Flexion Test

The aim of the study was to develop a novel real-time, computer-based synchronization system to continuously record pressure and craniocervical flexion ROM (range of motion) during the CCFT (craniocervical flexion test) in order to assess its feasibility for measuring and discriminating the values of ROM between different pressure levels. This was a descriptive, observational, cross-sectional, feasibility study. Participants performed a full-range craniocervical flexion and the CCFT. During the CCFT, a pressure sensor and a wireless inertial sensor simultaneously registered data of pressure and ROM. A web application was developed using HTML and NodeJS technologies. Forty-five participants successfully finished the study protocol (20 males, 25 females; 32 (11.48) years). ANOVAs showed large effect significant interactions between pressure levels and the percentage of full craniocervical flexion ROM when considering the 6 pressure reference levels of the CCFT (p < 0.001; η² = 0.697), 11 pressure levels separated by 1 mmHg (p < 0.001; η² = 0.683), and 21 pressure levels separated by 0.5 mmHg (p < 0.001; η² = 0.671). The novel time synchronizing system seems a feasible option to provide real-time monitoring of both pressure and ROM, which could serve as reference targets to further investigate the potential use of inertial sensor technology to assess or train deep cervical flexors.

Kinematic analysis of sensorimotor control during the craniocervical flexion movement in patients with neck pain and asymptomatic individuals: a cross-sectional study

BACKGROUND

Patients with craniocervical pain have shown reduced performance in the craniocervical flexion test (CCFT). However, there is limited evidence of other possible kinematic alterations not assessed in the context of the CCFT. Previous studies on other functional or planar movements have reported alterations in sensorimotor control (e.g., range of motion [ROM], velocity, or smoothness) in subjects with neck pain. The objective of this study was to explore the association between sensorimotor control variables associated with craniocervical flexion movement and different characteristics related to pain, age, disability, and fear of movement in individuals with non-traumatic chronic neck pain and asymptomatic controls.

METHODS

This was an observational, cross-sectional study in patients with non-traumatic neck pain and asymptomatic participants. Regression models were used to assess whether descriptive characteristics of the sample, including: (a) age, (b) intensity of pain, (c) neck disability, (d) chronicity of pain, and (e) fear of movement could explain sensorimotor control variables such as ROM, velocity, jerk, head repositioning accuracy, and conjunct motion. All these variables were recorded by means of light inertial measurement unit sensors during the performance of three maximal repetitions of full range craniocervical flexion in the supine position.

RESULTS

A total of 211 individuals were screened and 192 participants finished the protocol and were included in the analyses. Participants had an average age of 34.55 ± 13.93 years and included 124 patients with non-traumatic neck pain and 68 asymptomatic subjects. Kinesiophobia partially explained lower craniocervical flexion ROM (p = .01) and lower peak velocity in flexion (P < .001). Age partially explained increased craniocervical extension ROM (P < .001) and lower peak velocity in flexion (P = .03). Chronicity partially explained increased lateral flexion conjunct motion (P = .008). All models showed low values of explained variance (< 32%) and low absolute values of regression coefficients.

CONCLUSIONS

This study did not find a clear relationship between population characteristics and sensorimotor control variables associated with the craniocervical flexion movement. Kinesiophobia might have some association with reduced ROM in craniocervical flexion, but further research in this field is needed in large samples of patients with higher levels of kinesiophobia pain or disability.

Measures of neck muscle strength and their measurement properties in adults with chronic neck pain-a systematic review

BACKGROUND

Measurement of neck muscle strength is common during the assessment of people with chronic neck pain (CNP). This systematic review evaluates the measurement properties (reliability, validity, and responsiveness) of neck muscle strength measures in people with CNP.

DATABASES AND DATA TREATMENT

This systematic review followed a PROSPERO registered protocol (CRD42021233290). Electronic databases MEDLINE (OVID interface), CINAHL, SPORTDiscuss via (EBSCO interface), EMBASE (OVID interface), and Web of Science were searched from inception to 21 June 2021. Screening, data extraction, and quality assessment (Consensus-based Standards for the selection of Health Measurement Instruments (COSMIN) checklist) were conducted independently by two reviewers. The overall strength of evidence was evaluated using the modified Grading of Recommendations Assessment, Development and Evaluation.

RESULTS

From 794 records, nine articles were included in this review which concerned six different neck strength outcome measures. All studies evaluated reliability and one evaluated construct validity. The reliability of neck strength measures ranged from good to excellent. However, the risk of bias was rated as doubtful/inadequate for all except one study and the overall certainty of evidence was rated low/very low for all measures except for the measurement error of a handheld dynamometer.

CONCLUSION

A multitude of measures are used to evaluate neck muscle strength in people with CNP, but their measurement properties have not been fully established. Further methodologically rigorous research is required to increase the overall quality of evidence.

An experimental model of contusion injury in humans

INTRODUCTION

Contusion injuries are common in sport, but our knowledge of the responses to injury primarily come from animal studies and research using eccentric exercise. Therefore, the aim of this study was to develop a model of contusion injury in human participants and, additionally, investigate and compare physiological responses to four impact loads.

METHODS

Thirty-two males were exposed to a single impact of either 4.2, 5.2, 6.2 or 7.2kg, dropped from 67 cm, on to the vastus lateralis of one leg. Maximum voluntary and electrically induced quadriceps force, and pressure pain threshold were measured, and blood sampling carried out, prior to and 30min, 24, 48 and 72h post-impact. Magnetic resonance imaging was carried out 24h post-impact to quantify oedema.

RESULTS

Despite impact force with 7.2kg (1681.4 ± 235.6 N) not being different to 6.2kg (1690.7 ± 117.6 N), 7.2kg resulted in greater volume of oedema, voluntary force loss, pain and elevations in creatine kinase than the other loads. Although electrically induced force changed over time, post-hoc analysis failed to identify any changes. Interleukin-6 and prostaglandin-E2 did not change over time for any of the loads. Significant correlations were found between oedema volume, pressure pain threshold and maximum voluntary contraction force.

CONCLUSIONS

This is the first experimental study to investigate traumatic loading of skeletal muscle and the subsequent physiological responses associated with contusion injuries in humans. The absence of immediate elevations in creatine kinase and changes in electrically induced force suggest impact, with forces similar to those experienced in contact sport, does not cause significant, direct damage to skeletal muscle. However, the relationship between oedema volume, changes in pressure pain threshold and maximum voluntary contraction force suggests central inhibition plays a role in contusion-related muscle dysfunction.

Neck Pain: Do We Know Enough About the Sensorimotor Control System?

Neck pain is a worldwide health problem. Clarifying the etiology and providing effective interventions are challenging for the multifactorial nature of neck pain. As an essential component of cervical spine function, the sensorimotor control system has been extensively studied in both healthy and pathological conditions. Proprioceptive signals generated from cervical structures are crucial to normal cervical functions, and abnormal proprioception caused by neck pain leads to alterations in neural plasticity, cervical muscle recruitment and cervical kinematics. The long-term sensorimotor disturbance and maladaptive neural plasticity are supposed to contribute to the recurrence and chronicity of neck pain. Therefore, multiple clinical evaluations and treatments aiming at restoring the sensorimotor control system and neural plasticity have been proposed. This paper provides a short review on neck pain from perspectives of proprioception, sensorimotor control system, neural plasticity and potential interventions. Future research may need to clarify the molecular mechanism underlying proprioception and pain. The existing assessment methods of cervical proprioceptive impairment and corresponding treatments may need to be systematically reevaluated and standardized. Additionally, new precise motor parameters reflecting sensorimotor deficit and more effective interventions targeting the sensorimotor control system or neural plasticity are encouraged to be proposed.

A network analysis reveals the interaction between fear and physical features in people with neck pain

Although neck pain is known to be a complex and multifactorial condition characterised by the interplay between physical and psychological domains, a comprehensive investigation examining the interactions across multiple features is still lacking. In this study, we aimed to unravel the structure of associations between physical measures of neuromuscular function and fear of movement in people with a history of neck pain. One hundred participants (mean age 33.3 ± 9.4) were assessed for this cross-sectional study, and the neuromuscular and kinematic features investigated were the range of motion, velocity of neck movement, smoothness of neck movement, neck proprioception (measured as the joint reposition error), and neck flexion and extension strength. The Tampa Scale for Kinesiophobia was used to assess fear of movement. A network analysis was conducted to estimate the associations across features, as well as the role of each feature in the network. The estimated network revealed that fear of movement and neuromuscular/kinematic features were conditionally dependent. Higher fear of movement was associated with a lower range of motion, velocity, smoothness of neck movement, neck muscle strength, and proprioception (partial correlations between − 0.05 and − 0.12). Strong interactions were also found between kinematics features, with partial correlations of 0.39 and 0.58 between the range of motion and velocity, and between velocity and smoothness, respectively. The velocity of neck movement was the most important feature in the network since it showed the highest strength value. Using a novel approach to analysis, this study revealed that fear of movement can be associated with a spectrum of neuromuscular/kinematic adaptations in people with a history of neck pain.

Reliability and difference in neck extensor muscles strength measured by a portable dynamometer in individuals with and without chronic neck pain

OBJECTIVE

There are limited reports about the reliability of measuring neck extensor muscle strength using a portable dynamometer in neck pain patients. The aims of the current study were 1) to investigate intra- and inter-rater reliability of neck extensor isometric strength measurement using a portable dynamometer in patients with chronic nonspecific neck pain (CNSNP) and 2) to compare neck extensor isometric strength in participants with and without CNSNP.

METHODS

Guidelines for Reporting Reliability and Agreement Studies (GRRAS) were followed. Two examiners received a 15-minute training before enrollment. Inter-rater reliability was assessed with a 10-minute interval between measurements, and intra-rater reliability was assessed with a 10-day interval. Three trials were assessed and examiners were blind to the strength values (in Newtons) from other sessions of 20 individuals with CNSNP (mean±SD= 37.9 ± 9.8y; Neck Disability Index 29.2 ± 7.4%) and 20 individuals with other musculoskeletal disorders (mean ± SD = 32.8 ± 46.2y).

RESULTS

Intra-rater reliability was excellent with intraclass correlation coefficient (ICC)(3,1) of 0.95 (CI:0.90-0.97) and inter-rater reliability was good to excellent with ICC(2,1) of 0.88 (CI:0.77-0.94) in CNSNP. No significant difference of neck extensor strength was found between CNSNP (93.27N±31.94) and Individuals without CNSNP (111.43N±40.11) (p > 0.05).

CONCLUSION

A portable dynamometer is a reliable tool for measuring maximal isometric neck extension strength in individuals with CNSNP. Slightly but no significant differences of neck extensor strength values between individuals with and without CNSNP. Future studies are needed to assess the generalizability of the findings in patients with other muscle deconditioning.

Assessment of Neuromuscular and Psychological Function in People with Recurrent Neck Pain during a Period of Remission: Cross-Sectional and Longitudinal Analyses

The aim of this study was to examine for the presence of differences in neuromuscular and psychological function in individuals with recurrent neck pain (RNP) or chronic neck pain (CNP) following a whiplash trauma compared to healthy controls. A secondary aim was to examine whether neuromuscular characteristics together with psychological features in people with RNP were predictive of future painful episodes. Multiple features were assessed including neck disability, kinesiophobia, quality of life, cervical kinematics, proprioception, activity of superficial neck flexor muscles, maximum neck flexion and extension strength, and perceived exertion during submaximal contractions. Overall, those with RNP (n = 22) and CNP (n = 8) presented with higher neck disability, greater kinesiophobia, lower quality of life, slower and irregular neck movements, and less neck strength compared to controls (n = 15). Prediction analysis in the RNP group revealed that a higher number of previous pain episodes within the last 12 months along with lower neck flexion strength were predictors of higher neck disability at a 6-month follow-up. This preliminary study shows that participants with RNP presented with some degree of altered neuromuscular features and poorer psychological function with respect to healthy controls and these features were similar to those with CNP. Neck flexor weakness was predictive of future neck disability.

Using cervical movement velocity to assist the prediction of pain and functional recovery for people with chronic mechanical neck pain

BACKGROUND

Impaired cervical kinematics particularly the movement velocity had been consistently found in people with neck pain. The recovery and potential of cervical movement velocity in assisting the prediction of recovery in individuals with chronic neck pain remained unknown. This study investigated the application of cervical movement velocity to predict the outcomes of pain intensity and functional disability for a cohort of participants with chronic mechanical pain after completion of a 12-week intervention program.

METHODS

Cervical movement velocity when performing neck motions in the anatomical planes, pain intensity and functional disability score were assessed before and after the physiotherapy program. Correlations between kinematic and clinical outcomes, and validity of applying the peak velocity values of the cervical spine measured at baseline for prediction of recovery of pain and function after the physiotherapy program were examined (n = 68).

FINDINGS

Significant improvements were found in the peak values of cervical velocity in all movement planes, pain intensity and functional disability score at post-program reassessment (p < 0.001). Significant negative correlations between peak values of cervical movement velocity and pain intensity (for specific directions, r = -0.163 to -0.191), and functional disability were found (for all directions, r = -0.158 to -0.282). Area under the Receiver Operating Characteristics curve was >0.6 for cervical extension, flexion and right rotation velocity for predicting functional recovery post-program.

INTERPRETATION

These findings suggest that cervical velocity of selected planes measured at baseline may inform the prediction of recovery of functional disability but not pain intensity in people with chronic mechanical neck pain.

Development and Assessment of a Method to Estimate the Value of a Maximum Voluntary Isometric Contraction Electromyogram from Submaximal Electromyographic Data

The electromyographic (EMG) normalization (often to maximum voluntary isometric contraction [MVIC]) is used to control for interparticipant and day-to-day variations. Repeated MVIC exertions may be inadvisable from participants' safety perspective. This study developed a technique to predict the MVIC EMG from submaximal isometric voluntary contraction EMG. On day 1, 10 participants executed moment exertions of 100%, 60%, 40%, and 20% of the maximum (biceps brachii, rectus femoris, neck flexors, and neck extensors) as the EMG data were collected. On day 2, the participants replicated the joint moment values from day 1 (60%, 40%, and 20%) and also performed MVIC exertions. Using the ratios between the MVIC EMGs and submaximal isometric voluntary contraction EMG data values established on day 1, and the day 2 submaximal isometric voluntary contraction EMG data values, the day 2 MVIC EMGs were predicted. The average absolute percentage error between the predicted and actual MVIC EMG values for day 2 were calculated: biceps brachii, 45%; rectus femoris, 27%; right and left neck flexors, 27% and 33%, respectively; and right and left neck extensors, both 29%. There will be a trade-off between the required accuracy of the MVIC EMG and the risk of injury due to exerting actual MVIC. Thus, using the developed predictive technique may depend on the study circumstances.

An Investigation of Maximal Strength of the Upper Limb Bilaterally in Individuals With Lateral Elbow Tendinopathy: A Systematic Review With Meta-Analysis

OBJECTIVE

The aim of this study was to investigate whether there is evidence of bilateral upper limb strength deficits in individuals with unilateral lateral elbow tendinopathy (LET).

METHODS

The electronic databases Medline via Ovid, PubMed, and Scopus were searched from inception to March 2020. Included studies encompassed maximal strength outcomes of any upper limb and appendicular musculature in individuals with LET and an asymptomatic comparator. Study quality was rated using a modified version of the Epidemiological Appraisal Instrument. Hedges g effect sizes (ES) and 95% CIs were calculated for comparisons of maximal strength in the LET group and an asymptomatic control group. Meta-analysis using a random-effects model was performed when possible.

RESULTS

Fourteen studies were included. Quality appraisal resulted in a mean Epidemiological Appraisal Instrument score of 46% (SD = 10%). Meta-analysis revealed strength deficits in shoulder abduction (pooled ES = -0.37 [95% CI = -0.62 to -0.12]) and shoulder external rotation (pooled ES = -0.55 [95% CI = -0.83 to -0.28]) of the symptomatic limb compared with an asymptomatic control group. Meta-analysis also revealed maximal strength deficits in the upper trapezius (pooled ES = -0.26 [95% CI = -0.49 to -0.02]) of the asymptomatic limb compared with an asymptomatic control group. There was also consistent evidence for strength deficits in the serratus anterior, lower trapezius, and wrist extensor muscles and deficits in grip strength of the symptomatic limb as well as strength deficits in the wrist extensor muscles of the asymptomatic limb in individuals with unilateral LET.

CONCLUSION

In individuals with LET, there were maximal strength deficits in shoulder abduction, shoulder external rotation, serratus anterior and lower trapezius muscles, and wrist extension, as well as deficits in grip strength of the symptomatic limb compared with an asymptomatic control group. In addition, there appeared to be strength deficits in the upper trapezius muscle, wrist extension, and metacarpophalangeal joint flexion and extension, as well as deficits in grip strength of the asymptomatic limb in individuals with LET compared with an asymptomatic control group. These results suggest bilateral strength deficits.

IMPACT

These findings highlight the importance of a thorough physical examination and appropriate strengthening intervention for the upper limb with a focus on shoulder and scapular stabilizers, in addition to forearm muscles, in individuals with LET.

LAY SUMMARY

In people with tennis elbow, widespread strength deficits, including weakness of the shoulder, forearm, and wrist muscles, may exist. Interestingly, some of these weaknesses appear on both the affected and the unaffected sides in people with tennis elbow. A physical therapist can help strengthen these areas.

Machine learning approaches applied in spinal pain research

The purpose of this narrative review is to provide a critical reflection of how analytical machine learning approaches could provide the platform to harness variability of patient presentation to enhance clinical prediction. The review includes a summary of current knowledge on the physiological adaptations present in people with spinal pain. We discuss how contemporary evidence highlights the importance of not relying on single features when characterizing patients given the variability of physiological adaptations present in people with spinal pain. The advantages and disadvantages of current analytical strategies in contemporary basic science and epidemiological research are reviewed and we consider how analytical machine learning approaches could provide the platform to harness the variability of patient presentations to enhance clinical prediction of pain persistence or recurrence. We propose that machine learning techniques can be leveraged to translate a potentially heterogeneous set of variables into clinically useful information with the potential to enhance patient management.

How to improve the muscle synergy analysis methodology?

Muscle synergy analysis is increasingly used in domains such as neurosciences, robotics, rehabilitation or sport sciences to analyze and better understand motor coordination. The analysis uses dimensionality reduction techniques to identify regularities in spatial, temporal or spatio-temporal patterns of multiple muscle activation. Recent studies have pointed out variability in outcomes associated with the different methodological options available and there was a need to clarify several aspects of the analysis methodology. While synergy analysis appears to be a robust technique, it remain a statistical tool and is, therefore, sensitive to the amount and quality of input data (EMGs). In particular, attention should be paid to EMG amplitude normalization, baseline noise removal or EMG filtering which may diminish or increase the signal-to-noise ratio of the EMG signal and could have major effects on synergy estimates. In order to robustly identify synergies, experiments should be performed so that the groups of muscles that would potentially form a synergy are activated with a sufficient level of activity, ensuring that the synergy subspace is fully explored. The concurrent use of various synergy formulations-spatial, temporal and spatio-temporal synergies- should be encouraged. The number of synergies represents either the dimension of the spatial structure or the number of independent temporal patterns, and we observed that these two aspects are often mixed in the analysis. To select a number, criteria based on noise estimates, reliability of analysis results, or functional outcomes of the synergies provide interesting substitutes to criteria solely based on variance thresholds.

Estimating Muscle Forces for Breast Cancer Survivors During Functional Tasks

Breast cancer survivors have known scapular kinematic alterations that may be related to the development of secondary morbidities. A measure of muscle activation would help understand the mechanisms behind potential harmful kinematics. The purpose of this study was to define muscle force strategies in breast cancer survivors. Shoulder muscle forces during 6 functional tasks were predicted for 25 breast cancer survivors (divided by impingement pain) and 25 controls using a modified Shoulder Loading Analysis Module. Maximum forces for each muscle were calculated, and 1-way analysis of variance (P < .05) was used to identify group differences. The differences between maximum predicted forces and maximum electromyography were compared with repeated-measures analysis of variance (P < .05) to evaluate the success of the model predictions. Average differences between force predictions and electromyography ranged from 7.3% to 31.6% but were within the range of previously accepted differences. Impingement related pain in breast cancer survivors is associated with increased force of select shoulder muscles. Both pectoralis major heads, upper trapezius, and supraspinatus peak forces were higher in the pain group across all tasks. These force prediction differences are also associated with potentially harmful kinematic strategies, providing a direction for possible rehabilitation strategies.

A novel use of inertial sensors to measure the craniocervical flexion range of motion associated to the craniocervical flexion test: an observational study

Background

The craniocervical flexion test (CCFT) is recommended when examining patients with neck pain related conditions and as a deep cervical retraining exercise option. During the execution of the CCFT the examiner should visually assess that the amount of craniocervical flexion range of motion (ROM) progressively increases. However, this task is very subjective. The use of inertial wearable sensors may be a user-friendly option to measure and objectively monitor the ROM. The objectives of our study were (1) to measure craniocervical flexion range of motion (ROM) associated with each stage of the CCFT using a wearable inertial sensor and to determine the reliability of the measurements and (2) to determine craniocervical flexion ROM targets associated with each stage of the CCFT to standardize their use for assessment and training of the deep cervical flexor (DCF) muscles.

Methods

Adults from a university community able to successfully perform the CCFT participated in this study. Two independent examiners evaluated the CCFT in two separate sessions. During the CCFT, a small wireless inertial sensor was adhered to the centre of the forehead to provide real-time monitoring and to record craniocervical flexion ROM. The intra- and inter-rater reliability of the assessment of craniocervical ROM was calculated. This study was approved by the Research Ethics Committee of CEU San Pablo University (236/17/08).

Results

Fifty-six participants (18 males, 23 females; mean [SD] age, 21.8 [3.45] years) were included in the study and successfully completed the study protocol. All interclass correlation coefficient (ICC) values indicated good or excellent reliability of the assessment of craniocervical ROM using a wearable inertial sensor. There was high variability between subjects on the amount of craniocervical ROM necessary to achieve each stage of the CCFT.

Conclusions

The use of inertial sensors is a reliable method to measure the craniocervical flexion ROM associated with the CCFT. The great variability in the ROM limits the possibility to standardize a set of targets of craniocervical flexion ROM equivalent to each of the pressure targets of the pressure biofeedback unit.

Are neuromuscular adaptations present in people with recurrent spinal pain during a period of remission? A protocol for a systematic review

INTRODUCTION

The course of spinal pain (neck or low back pain) is often described as episodic and intermittent, with more than one-third of people continuing to experience episodic symptoms 1 year after first onset. Although ongoing neuromuscular adaptations could contribute to recurrent episodes of pain, no systematic review has synthesised evidence of ongoing neuromuscular changes in people with recurrent spinal pain during a period of symptom remission.

METHODS AND ANALYSIS

This protocol is developed and reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses-P, the Update of the Cochrane Back and Neck Group guidelines and the Methodological Expectations of Cochrane Intervention Reviews. PubMed, Web of Science, MEDLINE, EMBASE, CINAHL, ZETOC, Google Scholar, grey literature sources and key journals will be searched up to September 2019. Observational studies investigating neuromuscular changes in people with recurrent spinal pain during a period of remission will be included. Neuromuscular function will be considered under five outcome domains of muscle activity, spine kinematics, muscle properties, sensorimotor control and neuromuscular performance. Two independent reviewers will search, screen studies, extract data and assess risk of bias (Newcastle-Ottawa Scale). Data will be synthesised per outcome domain. Where clinical and methodological homogeneity across studies exists, a random-effects meta-analysis will be conducted. Otherwise, results will be synthesised narratively. The overall quality of evidence will be assessed using the Grading of Recommendations, Assessment, Development and Evaluation guidelines.

ETHICS AND DISSEMINATION

Findings of this review may aid the identification of factors that could contribute to spinal pain recurrence and aid the development of interventions for secondary prevention aimed at the restoration of optimal neuromuscular function. The results will be submitted for publication in a peer-reviewed journal and presented at conferences. No ethical approval was required.

PROSPERO REGISTRATION NUMBER

CRD42019141527.

Reliability of a Method to Measure Neck Surface Electromyography, Kinematics, and Pain Occurrence in Participants With Neck Pain

OBJECTIVE

To investigate the reliability of a novel method to measure neck surface electromyography (SEMG), kinematics, and pain during active movements in participants with neck pain.

METHODS

This test-retest study evaluated 23 participants with chronic neck pain. Each was measured twice within a single session. Three-dimensional kinematics and SEMG were recorded in 10° increments during forward and side flexion, extension, and rotation of the neck. Neck position during pain occurrence was also measured.

RESULTS

Intraclass correlation coefficients were >0.80 for 96% and 100% of SEMG and kinematic data, respectively. The percentage of standard error of the measurement (SEM) values were <25% for 91% of all SEMG measures; most were <15%, and some were <10%. For ranges of motion in the primary plane, percentage of SEM values were all <6% (SEM 1°-3°). Intraclass correlation coefficients for neck position during pain occurrence were all >0.60, except for right rotation (0.48) (SEM values 2°-8°). Pain occurred approximately 59% to 75% into the total range of motion and persisted to its end.

CONCLUSIONS

This methodology showed good reliability. It may be suitable for neck pain subclassification to evaluate the effects of treatment on pain, kinematics, and muscle activity during functional neck movements. The point of pain occurrence suggests increasing mechanical load on tissues may be one of the causative factors for movement-associated neck pain.

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.

Relationship Between Headaches and Neck Pain Characteristics With Neck Muscle Strength

OBJECTIVE

The purpose of this study was to assess the correlations between neck muscle strength and pain features, such as neck-related disability, neck pain frequency and intensity, and headache frequency in women with headache.

METHODS

Seventy women with migraine between 18 and 55 years of age diagnosed according to International Headache Society criteria were assessed. Participants provided clinical information regarding neck pain and headache. The Neck Disability Index was used to assess neck-related disability, and neck muscle strength was assessed via maximum voluntary contraction during flexion, extension, and lateral flexion with a handheld dynamometer. The correlation was verified with Spearman's correlation coefficient (ρ). Multiple linear regression was performed to verify whether the clinical variables could predict the strength of neck muscles. All calculations were performed adopting a level of significance of 0.05.

RESULTS

Neck extensor strength was negatively correlated with all clinical variables (ρ_range = -.24 to -.32, p < .05); lateral flexor strength was negatively correlated with headache frequency, neck pain intensity, and neck-related disability (ρ_range = -.27 to -.39, p < .05); and flexor strength also correlated negatively with neck pain intensity and related disability (ρ_r = -.26 to -.29, p < .05). Headache frequency and neck pain intensity were identified as significant predictors of the strength variability in extension (R² = 0.16, p < .05) and in lateral flexion (R² = 0.18, p < .05).

CONCLUSIONS

For the women with migraine in this study, correlations of headache and neck pain with neck muscle strength features were weakly to moderately negative. Headache frequency and neck pain intensity may influence a small proportion of the strength variability in extension and lateral flexion.

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.

Differences in neck surface electromyography, kinematics and pain occurrence during physiological neck movements between neck pain and asymptomatic participants. A cross-sectional study

BACKGROUND

Neck pain has been associated with altered muscle activity and impaired kinematics. Patients frequently report pain during physiological neck movements. Previously, the average muscle activity during these movements has been measured. However, muscle activity is modulated by the position in the range of movement, hence the study of neck muscle activity in discrete sections of the range of movement is warranted. Evidence is conflicting regarding range of movement restriction in neck pain. No study has assessed the point in the range of movement at which pain occurs. This study aimed to investigate neck kinematics, muscle activity and pain during physiological neck movements in participants with and without neck pain.

METHODS

Neck kinematics and surface electromyography were recorded continuously and analysed in 10° increments during forward and side flexion, extension and rotation of the neck in 20 neck pain and 20 asymptomatic participants. Point of pain occurrence in the range of movement was recorded.

FINDINGS

Neck pain participants demonstrated significantly lower activity of scalene during flexion and extension, and a non-significant higher activity in sternocleidomastoids during rotation. No differences in neck kinematics were observed. 65% of neck pain participants reported pain during at least one neck movement. Pain was reported in the last ≈20-40% of the range of movement.

INTERPRETATION

Exercises used in current practice to minimise scalene activity may not be appropriate for all neck pain patients. Restricted range of movement is not a consistent feature of neck pain. Movement associated neck pain is present at the end of range of movement, which has implications for the study of neck pain and rehabilitation.

Neck-specific exercise improves impaired interactions between ventral neck muscles in chronic whiplash: A randomized controlled ultrasound study

Chronic pain and disability is common in whiplash-associated disorders (WAD), leading to personal suffering, sick leave, and social cost. The cervical spine is heavily dependent on muscular support and whiplash injury can cause damage to the neck muscles, but diagnostic tools to measure neck muscle impairment and evaluate exercise interventions are lacking. Therefore, the present study investigated ventral neck muscle interactions in 26 individuals with chronic WAD randomized to neck-specific exercise (NSE) or remaining on a waiting list (WL) in 3 months. We performed real-time, non-invasive ultrasound measurements with speckle tracking analysis and calculated the deformation area and deformation rate in three ventral neck muscles. Multivariate statistics were used to analyse interactions between the muscles. After 3 months of NSE, significant improvements were observed in neck muscle interactions and pain intensity in the NSE group compared to the WL group. Thus, this study demonstrates that non-invasive ultrasound can be a diagnostic tool for muscle impairment and used to evaluate exercise interventions in WAD and stands to make a breakthrough for better management in chronic WAD.

Is there an association between fear avoidance beliefs, and pain and disability in patients with orofacial pain?

Numerous psychosocial factors have been shown to contribute to the development and perpetuation of orofacial pain. One well-recognized model for explaining the link between psychosocial factors and chronic pain is the fear avoidance model. To date, this proposed link has not been studied in subjects with orofacial pain. During the initial evaluation of subjects with orofacial pain, we collected data on fear avoidance beliefs using the Fear Avoidance Beliefs Questionnaire, and disability and pain. At between 6 and 8 weeks follow-up, we re-collected these data, as well as data addressing subjects' perceived change in their condition. Data were analyzed using correlation coefficients and linear regression. Fear avoidance beliefs at intake were inversely correlated with intake disability, There were no significant associations between fear avoidance beliefs at initial evaluation or in changes in fear avoidance beliefs during the 6-8 weeks follow-up period; and changes in disability, pain or perceived change in condition at 6-8 weeks follow-up. Of note, fear avoidance beliefs increased over the follow-up period, despite improvements in all outcome measures. There was insufficient evidence to suggest that high levels of fear avoidance beliefs at initial evaluation are associated with higher levels of disability or pain at intake, or with change in disability, pain or perceived change in condition at 6-8 weeks follow-up. Similarly, there was insufficient evidence to suggest that changes in fear avoidance beliefs during treatment are associated with any of these outcome measures.

Associations between psychological factors and the effect of home-based physical exercise in women with chronic neck and shoulder pain

BACKGROUND

Exercise is often used in the treatment of chronic neck and shoulder muscle pain. It is likely that psychological aspects have an impact on the results of exercise-based treatments.

OBJECTIVES

(1) To examine the associations between psychological factors and the effect of a home-based physical exercise intervention. (2) To examine differences in psychological factors at baseline between (a) subjects who continued in the trial and those who did not and (b) subjects who completed the intervention and those who did not.

METHOD

A total of 57 women with chronic neck and shoulder pain were included in a home-based exercise intervention trial. Pain intensity, disability, and psychological factors (anxiety and depression symptoms, catastrophizing, fear-avoidance beliefs, self-efficacy, and pain acceptance) were measured at baseline, after 4-6 months, and after 1 year of exercise. Associations between the psychological factors and changes in pain intensity and disability were analysed, as well as differences in psychological factors at baseline between subjects who continued in and completed the intervention, and those who did not.

RESULTS

Associations between positive changes in pain intensity and disability were found for low fear-avoidance beliefs and low-pain self-efficacy at baseline. In addition, fear-avoidance beliefs at baseline were higher in the subjects who dropped out of the intervention than in those who continued. Pain acceptance at baseline was higher in the subjects who completed the intervention at the end of the trial.

CONCLUSION

Particularly, fear-avoidance beliefs and pain self-efficacy should be taken into consideration when implementing home-based physical exercise as treatment for chronic neck pain. In addition, high pain acceptance might improve the adherence to prescribed exercise.

Reduced Maximal Force during Acute Anterior Knee Pain Is Associated with Deficits in Voluntary Muscle Activation

Although maximal voluntary contraction (MVC) force is reduced during pain, studies using interpolated twitch show no consistent reduction of voluntary muscle drive. The present study aimed to test if the reduction in MVC force during acute experimental pain could be explained by increased activation of antagonist muscles, weak voluntary activation at baseline, or changes in force direction. Twenty-two healthy volunteers performed maximal voluntary isometric knee extensions before, during, and after the effects of hypertonic (pain) and isotonic (control) saline injections into the infrapatellar fat pad. The MVC force, voluntary activation, electromyographic (EMG) activity of agonist, antagonist, and auxiliary (hip) muscles, and pain cognition and anxiety scores were recorded. MVC force was 9.3% lower during pain than baseline (p < 0.001), but there was no systematic change in voluntary activation. Reduced MVC force during pain was variable between participants (SD: 14%), and was correlated with reduced voluntary activation (r = 0.90), baseline voluntary activation (r = − 0.62), and reduced EMG amplitude of agonist and antagonist muscles (all r > 0.52), but not with changes in force direction, pain or anxiety scores. Hence, reduced MVC force during acute pain was mainly explained by deficits in maximal voluntary drive.

Is synergistic organisation of muscle coordination altered in people with lateral epicondylalgia? A case-control study

BACKGROUND

Lateral epicondylalgia is a common musculoskeletal disorder and is associated with deficits in the motor system including painful grip. This study compared coordination of forearm muscles (muscle synergies) during repeated gripping between individuals with and without lateral epicondylalgia.

METHODS

Twelve participants with lateral epicondylalgia and 14 controls performed 15 cyclical repetitions of sub-maximal (20% maximum grip force of asymptomatic arm), pain free dynamic gripping in four arm positions: shoulder neutral with elbow flexed to 90° and shoulder flexed to 90° with elbow extended both with forearm pronated and neutral. Muscle activity was recorded from extensor carpi radialis brevis/longus, extensor digitorum, flexor digitorum superficialis/profundus, and flexor carpi radialis, with intramuscular electrodes. Muscle synergies were extracted using non-negative matrix factorisation.

FINDINGS

Analysis of each position and participant, demonstrated that two muscle synergies accounted for >97% of the variance for both groups. Between-group differences were identified after electromyography patterns of the control group were used to reconstruct the patterns of the lateral epicondylalgia group. A greater variance accounted for was identified for the controls than lateral epicondylalgia (p=0.009). This difference might be explained by an additional burst of flexor digitorum superficialis electromyography during grip release in many lateral epicondylalgia participants.

INTERPRETATION

These data provide evidence of some differences in synergistic organisation of activation of forearm muscles between individuals with and without lateral epicondylalgia. Due to study design it is not possible to elucidate whether changes in the coordination of muscle activity during gripping are associated with the cause or effect of lateral epicondylalgia.

Cervical-scapular muscles strength and severity of temporomandibular disorder in women with mechanical neck pain

Abstract Introduction: Changes in cervical muscle function have been observed in patients with neck pain (NP) and TMD. However, the relationship between TMD severity and neck muscle strength in the presence/absence of NP is unknown. Objective: To determine the prevalence of TMD in women with and without mechanical NP and assess the cervical-scapular muscle strength and its association with TMD severity. Methods: Fifteen volunteers without neck pain (CG) and 14 women with mechanical neck pain (NPG) took part and were selected by the Neck Disability Index. The diagnosis and severity of TMD were determined by the Research Diagnostic Criteria for TMD and Temporomandibular Index (TI), respectively. The strength of the upper trapezius muscle, and cervical flexor and extensor muscles was measured by digital hand dynamometer. Results: 64.5% of women with NP and 33.3% without NP were diagnosed with TMD (p = 0.095). The NPG showed lower strength of the cervical flexor (p = 0.044) and extensor (p=0.006) muscles, and higher TI (p = 0.038) than in the CG. It was also verified moderate negative correlation between TI and the strength of dominant (p = 0.046, r = -0.547) and non-dominant (p = 0.007, r = -0.695) upper trapezius, and cervical flexors (p = 0.023, r = -0.606) in the NPG. Conclusion: There was no difference in the prevalence of TMD in women with and without NP. However, women with NP have lower cervical muscle strength - compared to those without NP - which was associated with greater severity of TMD. Thus, in women with NP associated with TMD, it is advisable to assess and address the severity of this dysfunction and identify the cervical-scapular muscles compromise.

Head repositioning accuracy in patients with neck pain and asymptomatic subjects: concurrent validity, influence of motion speed, motion direction and target distance

BACKGROUND

Cervicocephalic kinesthetic deficiencies have been demonstrated in patients with chronic neck pain (NP). On the other hand, authors emphasized the use of different motion speeds for assessing functional impairment of the cervical spine.

PURPOSE

The objectives of this study were (1) to investigate the head repositioning accuracy in NP patients and control subjects and (2) to assess the influence of target distance, motion speed, motion direction and pain.

MATERIALS AND METHODS

Seventy-one subjects (36 healthy subjects and 35 NP patients; age 30-55 years) performed the head repositioning test (HRT) at two different speeds for horizontal and vertical movements and at two different distances. For each condition, six consecutive trials were sampled.

RESULTS

The study showed the validity and reproducibility of the HRT, confirming a dysfunctional threshold of 4.5°. Normative values of head repositioning error up to 3.6° and 7.1° were identified for healthy and NP subjects, respectively. A distance of 180 cm from the target and a natural motion speed increased HRT accuracy. Repositioning after extension movement showed a significantly larger error in both groups. Intensity, duration of pain as well as pain level did not significantly alter head repositioning error.

CONCLUSIONS

The assessment of proprioceptive performance in healthy and NP subjects allowed the validation of the HRT. The HRT is a simple, not expensive and fast test, easily implementable in daily practice to assess and monitor treatment and evolution of proprioceptive cervical deficits.

Experimental Muscle Pain Impairs the Synergistic Modular Control of Neck Muscles

A motor task can be performed via different patterns of muscle activation that show regularities that can be factorized in combinations of a reduced number of muscle groupings (also referred to as motor modules, or muscle synergies). In this study we evaluate whether an acute noxious stimulus induces a change in the way motor modules are combined to generate movement by neck muscles. The neck region was selected as it is a region with potentially high muscular redundancy. We used the motor modules framework to assess the redistribution of muscular activity of 12 muscles (6 per side) in the neck region of 8 healthy individuals engaged in a head and neck aiming task, in non-painful conditions (baseline, isotonic saline injection, post pain) and after the injection of hypertonic saline into the right splenius capitis muscle. The kinematics of the task was similar in the painful and control conditions. A general decrease of activity was noted for the injected muscle during the painful condition together with an increase or decrease of the activity of the other muscles. Subjects did not adopt shared control strategies (motor modules inter subject similarity at baseline 0.73±0.14); the motor modules recorded during the painful condition could not be used to reconstruct the activation patterns of the control conditions, and the painful stimulus triggered a subject-specific redistribution of muscular activation (i.e., in some subjects the activity of a given muscle increased, whereas in other subjects it decreased with pain). Alterations of afferent input (i.e., painful stimulus) influenced motor control at a multi muscular level, but not kinematic output. These findings provide new insights into the motor adaptation to pain.

Neck and shoulder muscle strength in patients with tension-type headache: A case-control study

Introduction

Tension-type headache (TTH) is highly prevalent in the general population, and it is characterized by increased muscle tenderness with increasing headache frequency and intensity.

Aim

The aim of this case-control study was to compare muscle strength in neck and shoulder muscles in TTH patients and healthy controls by examining maximal voluntary isometric contraction (MVC) during shoulder abduction, neck flexion and extension as well as the extension/flexion strength ratio of the neck.

Methods

Sixty TTH patients and 30 sex- and age-matched healthy controls were included. Patients were included if they had TTH ≥8 days per month. The MVC neck extensor and flexor muscles were tested with the participant seated upright. MVC shoulder abduction was tested with the individual lying supine.

Results

Compared to controls TTH patients had significantly weaker muscle strength in neck extension ( p = 0.02), resulting in a significantly lower extension/flexion moment ratio ( p = 0.03). TTH patients also showed a tendency toward significantly lower muscle strength in shoulder abduction ( p = 0.05). Among the 60 TTH patients, 25 had frequent episodic TTH (FETTH), and 35 had chronic TTH (CTTH).

Conclusion

Patients with TTH exhibited decreased muscle strength in the neck extensor muscles, inducing a reduced cervical extension/flexion ratio compared to healthy people.

Evidence for a general stiffening motor control pattern in neck pain: a cross sectional study

BACKGROUND

Neck pain is associated with several alterations in neck motion and motor control. Previous studies have investigated single constructs of neck motor control, while few have applied a comprehensive set of tests to investigate cervical motor control. This comparative cross- sectional study aimed to investigate different motor control constructs in neck pain patients and healthy controls.

METHODS

A total of 166 subjects participated in the study, 91 healthy controls (HC) and 75 neck pain patients (NP) with long-lasting moderate to severe neck pain. Neck flexibility, proprioception, head steadiness, trajectory movement control, and postural sway were assessed using a 3D motion tracking system (Liberty). The different constructs of neck motion and motor control were based on tests used in previous studies.

RESULTS

Neck flexibility was lower in NP compared to HC, indicated by reduced cervical ROM and conjunct motion. Movement velocity was slower in NP compared to HC. Tests of head steadiness showed a stiffer movement pattern in NP compared to HC, indicated by lower head angular velocity. NP patients departed less from a predictable trajectory movement pattern (figure of eight) compared to healthy controls, but there was no difference for unpredictable movement patterns (the Fly test). No differences were found for postural sway in standing with eyes open and eyes closed. However, NP patients had significantly larger postural sway when standing on a balance pad. Proprioception did not differ between the groups. Largest effect sizes (ES) were found for neck flexibility (ES range: 0.2-0.8) and head steadiness (ES range: 1.3-2.0). Neck flexibility was the only construct that showed a significant association with current neck pain, while peak velocity was the only variable that showed a significant association with kinesiophobia.

CONCLUSIONS

NP patients showed an overall stiffer and more rigid neck motor control pattern compared to HC, indicated by lower neck flexibility, slower movement velocity, increased head steadiness and more rigid trajectory head motion patterns. Only neck flexibility showed a significant association with clinical features in NP patients.

Inter-and intra-tester reliability of a battery of cervical movement control dysfunction tests

BACKGROUND

Apart from the cranio-cervical flexion test and the deep neck flexor endurance test, evidence related to reliability of cervical movement control dysfunction tests is lacking.

OBJECTIVES

This study investigated the inter- and intra-tester reliability of a battery of cervical movement control dysfunction tests and the effect of clinician experience on reliability in 15 patients with chronic neck pain and 17 non-neck pain controls. In addition, it explored whether impaired performance on this battery of tests was more frequently observed in the neck pain group.

DESIGN

Inter and intra-tester reliability study.

METHOD

Participants were videotaped while performing a battery of nine active cervical movement control dysfunction tests. Two physiotherapists, with different levels of experience, independently rated all tests on two occasions two weeks apart. They were masked to participants' neck pain or non-neck pain status.

RESULTS

Inter-tester reliability for the complete battery of tests was substantial (κ = 0.69; 95% CI: 0.62, 0.76). Intra-rater reliability values for the expert (κ = 0.86; 95% CI: 0.79, 0.92) and novice (κ = 0.76; 95% confidence intervals (CI): 0.68, 0.84) were overall comparable suggesting that novices can achieve good accuracy with the battery of tests if trained. The frequency of impaired performances in cervical movement control dysfunction tests was low and comparable between groups. Only two tests achieved a greater number of impaired ratings in the patient group.

CONCLUSIONS

Although reliable, further research in larger neck pain populations is required to explore this battery of tests, in order to establish their diagnostic accuracy for identifying clinically relevant cervical movement control dysfunction.