Changes in the activity of the muscles surrounding the neck according to the angles of movement of the neck in adults in their 20s

[Purpose] The aim of this study was to examine changes in the muscle activity around the neck according to the neck movement angle during neck flexion and extension. [Subjects and Methods] Activities of the sternocleidomastoid muscle (SCM), splenius capitis and splenius cervicis muscles, upper trapezius muscle, and middle trapezius muscle during flexion and extension were assessed in 24 college students. [Results] SCM muscle activation significantly increased at every angle during flexion and extension. The activities of the splenius capitis and splenius cervicis muscles increased significantly during flexion. The activity of the upper trapezius muscle also increased significantly. [Conclusion] The results highlight the need for individuals not to adopt a neck flexion posture for extended periods.Key words: Neck muscles, Electromyography, Muscle activation     

The effect of forward head posture on muscle activity during neck protraction and retraction

[Purpose] The present study was performed to investigate whether forward head posture (FHP) affects muscle activity. [Subjects and Methods] Twenty subjects attending Y university in Gyeongsangnam-do, Republic of Korea. They were divided into two groups according to craniovertebral angle: a control group (n=10) and a FHP group (n=10). Electromyography electrodes were attached to the upper fibers of the trapezius, middle fibers of the trapezius, the splenii (splenius capitis and splenius cervicis), and the sternocleidomastoid (SCM) muscle to measure muscle activity during the neck protraction and retraction. [Results] EMG activities of the middle trapezius, splenii, and SCM muscle showed significant differences between the control group and the FHP group. However, the EMG activity of the upper trapezius muscle showed no significant difference between the two groups during neck protraction and retraction. [Conclusion] The results suggest that FHP alters the muscle activity in neck protraction and retraction.Key words: Forward head posture, Muscle activity, Electromyography     

Effect of Assistive Device for Neck Retraction (ANR) on Neck Muscles during Neck Retraction Exercise

[Purpose] The purpose of present study was to develop an exercise device for assisting neck retraction exercise and to investigate its effectiveness. [Subjects] Fifteen male subjects were recruited. [Methods] The subjects performed the neck retraction exercises with and without assistive device for neck retraction (ANR). EMG activities of the lower cervical erector spinae (LCE), and sternocleidomatoid (SCM) muscles were recorded. [Results] The ANR condition significantly increased LCE activation compared to the control condition. The ANR condition significantly decreased SCM activation compared to the control condition. [Conclusion] We suggest that the ANR condition will help the efficacy of the neck retraction exercise.Key words: Electromyography, Forward head posture, Neck retraction exercise     

Altered Co-contraction of Cervical Muscles in Young Adults with Chronic Neck Pain during Voluntary Neck Motions

[Purpose] Muscle co-contraction is important in stabilizing the spine. The aim of this study was to compare cervical muscle co-contraction in adults with and without chronic neck pain during voluntary movements. [Subjects and Methods] Surface electromyography of three paired cervical muscles was measured in fifteen young healthy subjects and fifteen patients with chronic neck pain. The subjects performed voluntary neck movements in the sagittal and coronal plane at slow speed. The co-contraction ratio was defined as the normalized integration of the antagonistic electromyography activities divided by that of the total muscle activities. [Results] The results showed that the co-contraction ratio of patients was greater during flexion movement, lesser during extension movement, slightly greater during right lateral bending, and slightly lesser during left lateral bending compared with in the controls. [Conclusion] The results suggested that neck pain patients exhibit greater antagonistic muscle activity during flexion and dominate-side bending movements to augment spinal stability, while neuromuscular control provides relatively less protection in the opposite movements. This study helps to specify the changes of the stiffness of the cervical spine in neck pain patients and provides a useful tool and references for clinical assessment of neck disorders.Key words: Co-contraction, Chronic neck pain, Electromyography     

Effect of the Neck Retraction Taping (NRT) on Forward Head Posture and the Upper Trapezius Muscle during Computer Work

[Purpose] The purpose of this study was to investigate the effect of neck retraction taping on forward head posture and the upper trapezius muscle of computer workers during computer work. [Subjects] Twelve males aged 20–30 years were recruited. [Methods] We measured forward head angle and upper trapezius muscle activity during computer work before and after NRT. [Results] The FHP angle significantly decreased during computer work performed with NRT compared to without NRT. The UT muscle activity was also significantly decreased during computer work performed with NRT compared to without NRT. [Conclusion] We think that the taping tension provided by NRT may have provided a mechanical effect that prevented FHP. NRT may also encourage a proper head posture in patients unfamiliar with the neck retraction posture.Key words: Forward head posture, Neck retraction, Taping     

Characteristics of Cervical Position Sense in Subjects with Forward Head Posture

[Purpose] The purpose of this study was to investigate the effect of forward head posture (FHP) on proprioception by determining the cervical position-reposition error. [Subjects and Methods] A sample population was divided into two groups in accordance with the craniovertebral angle: the FHP group and the control group. We measured the craniovertebral angle, which is defined as the angle between a horizontal line passing through C7 and a line extending from the tragus of the ear to C7. The error value of the cervical position sense after cervical flexion, extension, and rotation was evaluated using the head repositioning accuracy test. [Results] There were significant differences in the error value of the joint position sense (cervical flexion, extension, and rotation) between the FHP and control groups. In addition, there was an inverse correlation between the craniovertebral angle and error value of the joint position sense. [Conclusion] FHP is associated with reduced proprioception. This result implies that the change in the muscle length caused by FHP decreases the joint position sense. Also, proprioception becomes worse as FHP becomes more severe.Key words: Forward head posture, Joint position sense, Proprioception     

A Comparison of the Deep Cervical Flexor Muscle Thicknesses in Subjects with and without Neck Pain during Craniocervical Flexion Exercises

[Purpose] The purpose of the present study was to examine the amount of change in the thicknesses of the deep cervical flexor (DCF) and sternocleidomastoid (SCM) muscles in subjects with neck pain and subjects without neck pain during craniocervical flexion exercise (CCFE). [Subjects] The total number of subjects was 40, comprising 20 in the no-pain group (males 11, females 9) and 20 in the pain group (males 8, females 12). [Methods] Muscle images were obtained using ultrasound, and the thicknesses of the individual muscles were measured using the NIH ImageJ software. [Results] During CCFE, as pressure increased, the no-pain group recruited the DCF more than the pain group, while the pain group recruited the SCM more. [Conclusion] Selective DCF contraction exercises are considered very useful in the treatment of patients with neck pain.Key words: Craniocervical flexion exercise, Deep cervical flexor, Sternocleidomastoid     

Effects of Neck Exercise on High-School Students’ Neck–Shoulder Posture

[Purpose] This study examined the effects of deep flexor muscle-strengthening exercise on the neck–shoulder posture, and the strength and endurance of the deep flexor muscles of high-school students. [Subjects] The subjects were 30 seventeen-year-old female high-school students who complained about bad posture and chronic neck–shoulder pain. They were randomly divided into an experimental group of 15 subjects, who performed a deep flexor muscle-strengthening exercise and a control group of 15 subjects, who performed a basic stretching exercise. [Methods] The experimental group of 15 subjects performed a deep flexor muscle-strengthening exercise consisting of low-load training of the cranio-cervical flexor muscle, and the control group of 15 subjects performed a basic stretching exercise consisting of seven motions. [Results] The experimental group showed statistically significant changes in head tilt angle, neck flexion angle, forward shoulder angle, and the result of the cranio-cervical flexion test after the training. In contrast, the control group showed no statistically significant changes in these measures following the training. When the results of the groups were compared, statistically significant differences were found for all items between the experimental group and the control group. [Conclusion] Strengthening cranio-cervical flexor muscles is important for the adjustment of neck posture, and maintaining their stability is required to improve neck-shoulder posture.Key words: Cranio-cervical flexion training, Forward head posture, Neck exercise     

Influence of neck pain on cervical movement in the sagittal plane during smartphone use

[Purpose] Smartphone use reportedly changes posture. However, how neck posture is altered in smartphone users with neck pain is unknown. This study examined changes in the posture of young adults with and without mild neck pain (MNP) when using a smartphone. [Subjects] Thirteen control subjects and 14 subjects with MNP who used smartphones were recruited. [Methods] The upper cervical (UC) and lower cervical (LC) angles in the sagittal plane were measured using an ultrasound-based motion analysis system while the seated subjects used a smartphone for 5 min. [Results] During smartphone use, the MNP group exhibited greater UC and LC flexion angles than the control group. [Conclusion] These findings suggest that young adults with MNP are more careful and more frequently utilize a neutral neck posture than young adults without MNP when using a smartphone while sitting.Key words: Smartphone, Cervical flexion, Young adult     

The effects of cervical joint manipulation,based on passive motion analysis, on cervical lordosis,forward head posture,and cervical ROM in university students with abnormal posture of the cervical spine

[Purpose] The aim of this study was to determine the effect of cervical posture manipulation, based on passive motion analysis (MBPMA) and general mobilization, on cervical lordosis, forward head posture (FHP), and cervical ROM in university students with problems in cervical posture and range of motion (ROM). [Subjects] The Subjects were 40 university students in their 20s who displayed problems in cervical posture and ROM; they were divided into an MBPMA group (n=20) and a mobilization group (n=20). [Methods] Each group underwent MBPMA or mobilization three times a week for four weeks. The effects of MBPMA and mobilization on cervical lordosis, FHP, and cervical ROM were analyzed by radiography. [Results] MBPMA was effective in increasing the cervical lordosis, cervical extension ROM (CER), and ranges of flexion and extension motion (RFEM) and in decreasing FHP. Mobilization was effective in increasing CER and decreasing FHP. [Conclusion] MBPMA can be utilized as an effective method for decreasing FHP and improving cervical lordosis and cervical ROM.Key words: Manipulation, Motion analysis, Cervical ROM     

Electromyography activity of the deltoid muscle of the weight-bearing side during shoulder flexion in various weight-bearing positions

[Purpose] This study investigated the deltoid muscle activation during shoulder flexion exercise in various weight-bearing positions. [Subjects] A total of 15 males participated. [Methods] The participants completed three repetitions of shoulder flexion exercises in three positions (prone-on-elbow, quadruped, and standing) with electromyography activity being collected from the exercised. The muscle activations in each position by each exercise were compared using a one-way analysis of variance. [Results] The electromyography activities of the middle and posterior deltoids differed significantly among positions. The prone-on-elbow and quadruped position showed a significantly higher activity than the standing position. There were no significant differences between the prone-on-elbow and quadruped positions. [Conclusion] The deltoid muscles were further strengthened in the low posture positions (prone-on-elbows and quadruped) than in standing.Key words: Electromyography, Deltoid, Weight bearing     

Comparison of the Forward Head Angle and the Lumbar Flexion and Rotation Angles of Computer Workers Using Routine and Individually Fixed Computer Workstations

[Purpose] This study compared the forward head angle and the lumbar flexion and rotation angles of computer workers using routine and fixed computer workstations. [Subjects] Ten male workers voluntarily consented to participate in the study. [Methods] A 3-D motion analysis system was used to measure the angles of the forward head and lumbar flexion. All subjects performed computer work for 30 minutes using both types of workstation. [Results] When working at the fixed workstation, the forward head angle was less than that observed when the routine workstation was used. At the fixed workstation, the lumbar flexion and rotation angles were less than that at the routine workstation. [Conclusion] The computer workstation individually fixed for standard posture may have prevented poor sitting posture.Key words: Computer workstation, Forward head angle, Sitting posture     

Shoulder function and 3-dimensional scapular kinematics in people with and without shoulder impingement syndrome

BACKGROUND AND PURPOSE: Several factors such as posture, muscle force, range of motion, and scapular dysfunction are commonly believed to contribute to shoulder impingement. The purpose of this study was to compare 3-dimensional scapular kinematics, shoulder range of motion, shoulder muscle force, and posture in subjects with and without primary shoulder impingement syndrome. SUBJECTS: Forty-five subjects with impingement syndrome were recruited and compared with 45 subjects without known pathology or impairments matched by age, sex, and hand dominance. METHODS: Shoulder motion and thoracic spine posture were measured goniometrically, and force was measured with a dynamometer. An electromagnetic motion analysis system was used to capture shoulder kinematics during active elevation in both the sagittal and scapular planes as well as during external rotation with the arm at 90 degrees of elevation in the frontal plane. RESULTS: The impingement group demonstrated slightly greater scapular upward rotation and clavicular elevation during flexion and slightly greater scapular posterior tilt and clavicular retraction during scapular-plane elevation compared with the control group. The impingement group demonstrated less range of motion and force in all directions compared with the control group. There were no differences in resting posture between the groups. DISCUSSION AND CONCLUSION: The kinematic differences found in subjects with impingement may represent scapulothoracic compensatory strategies for glenohumeral weakness or motion loss. The decreased range of motion and force found in subjects with impingement support rehabilitation approaches that focus on strengthening and restoring flexibility.     

The Intra- and Inter-rater Reliabilities of the Forward Head Posture Assessment of Normal Healthy Subjects

[Purpose] Assessment of posture is an important goal of physical therapy interventions for preventing the progression of forward head posture (FHP). The purpose of this study was to determine the inter- and intra-rater reliabilities of the assessment of FHP. [Subjects and Methods] We recruited 45 participants (20 male subjects, 25 female subjects) from a university student population. Two physical therapists assessed FHP using images of head extension. FHP is characterized by the measurement of angles and distances between anatomical landmarks. Forward shoulder angle of 54° or less was defined as FHP. Intra- and inter-rater reliabilities were estimated using Kendall’s Taub correlation coefficients. [Results] Intra-class correlation of intra-rater measurements indicated an excellent level of reliability (0.91), and intra-class correlation of inter-rater measurements showed a good level of reliability in the assessment of FHP (0.75). [Conclusion] Assessment of FHP is an important component of evaluation and affects the design of the treatment regimen. The assessment of FHP was reliably measured by two physical therapists. It could therefore become a useful method for assessing FHP in the clinical setting. Future studies will be needed to provide more detailed quantitative data for accurate assessment of posture.Key words: Forward head posture, Reliability, Posture assessment     

Electromyography of symmetrical trunk movements and trunk position sense in chronic stroke patients

[Purpose] To explore the differences in bilateral trunk muscle activation between chronic stroke patients and healthy controls, this study investigated the symmetry index and cross-correlation of trunk muscles during trunk flexion and extension movements. This study also assessed the differences in trunk reposition error between groups and the association between trunk reposition error and bilateral trunk muscle activation. [Subjects and Methods] Fifteen stroke patients and 15 age- and gender-matched healthy subjects participated. Bilateral trunk muscle activations were collected by electromyography during trunk flexion and extension. Trunk reposition errors in trunk flexion and extension directions were recorded by a Qualisys motion capture system. [Results] Compared with the healthy controls, the stroke patients presented lower symmetrical muscle activation of the bilateral internal oblique and lower cross-correlation of abdominal muscles during trunk flexion, and lower symmetry index and cross-correlation of erector spinae in trunk extension. They also showed a larger trunk extension reposition error. A smaller trunk reposition error was associated with higher cross-correlation of bilateral trunk muscles during trunk movements in all subjects. [Conclusion] Trunk muscle function during symmetrical trunk movements and trunk reposition sense were impaired in the chronic stroke patients, and trunk position sense was associated with trunk muscle functions. Future studies should pay attention to symmetrical trunk movements as well as trunk extension position sense for patients with chronic stroke.Key words: Stroke, Electromyography, Trunk reposition sense     

Myofascial trigger points, neck mobility and forward head posture in unilateral migraine

This paper describes the differences in the presence of myofascial trigger points (TrPs) in the upper trapezius, sternocleidomastoid, temporalis and suboccipital muscles between unilateral migraine subjects and healthy controls, and the differences in the presence of TrPs between the symptomatic side and the non-symptomatic side in migraine subjects. In addition, we assess the differences in the presence of both forward head posture (FHP) and active neck mobility between migraine subjects and healthy controls and the relationship between FHP and neck mobility. Twenty subjects with unilateral migraine without side-shift and 20 matched controls participated. TrPs were identified when there was a hypersensible tender spot in a palpable taut band, local twitch response elicited by the snapping palpation of the taut band and reproduction of the referred pain typical of each TrP. Side-view pictures were taken in both sitting and standing positions to measure the cranio-vertebral angle. A cervical goniometer was employed to measure neck mobility. Migraine subjects showed a significantly greater number of active TrPs (P<0.001), but not latent TrPs, than healthy controls. Active TrPs were mostly located ipsilateral to migraine headaches (P<0.01). Migraine subjects showed a smaller cranio-vertebral angle than controls (P<0.001), thus presenting a greater FHP. Neck mobility in migraine subjects was less than in controls only for extension (P=0.02) and the total range of motion in flexion/extension (P=0.01). However, there was a positive correlation between the cranio-vertebral angle and neck mobility. Nociceptive inputs from TrPs in head and neck muscles may produce continuous afferent bombardment of the trigeminal nerve nucleus caudalis and, thence, activation of the trigeminovascular system. Active TrPs located ipsilateral to migraine headaches might be a contributing factor in the initiation or perpetuation of migraine.     

Kinematic and electromyographic response to whiplash-type impacts. Effects of head rotation and trunk flexion: summary of research

Despite the fact that whiplash patients often report they had their head rotated or were in a twisted posture at the time of impact, the effect of these postures on the cervical muscle response to impact remains uninvestigated in impact studies. Prior impact studies have positioned the volunteers in the recommended driving position, for example, with head and trunk in a neutral posture. Using an approach of sled impacts with volunteers in very-low velocity impacts to describe the head kinematics and cervical muscle electromyography in response has provided a wealth of data. From this approach, the effect of varying impact direction and level of impact awareness can be discerned without subjecting the volunteers to injury. In part 1 of this review, a further series of results of impacts from eight directions is presented, revealing that the cervical electromyography response to whiplash-type impacts varies according to the presence and direction of head rotation. In part 2, additional data is summarised concerning whiplash-type impacts from 8 directions in the presence of trunk flexion. Contrary to a popular notion, head rotation or trunk flexion at the time of impact are factors that probably reduce injury risk. This data adds to attempts to approach an understanding of the human response to more complex scenarios of low-velocity road collisions.     

Effects of Cervical Flexion on the Flexion-relaxation Ratio during Smartphone Use

[Purpose] The purpose of this study was to measure the cervical flexion-relaxation ratio (FRR) and intensity of neck pain and identify the differences according to postures adopted while using smartphones. [Subjects] Fifteen healthy adults with no neck pain, spinal trauma, or history cervical surgery participated in this study. [Methods] The activity of the cervical erector spinae muscle was recorded while performing a standardized cervical flexion-extension movement in three phases (flexion, sustained full flexion, extension). And neck pain intensity was recorded using a visual analog scale (VAS) with values between 0 and 10. Postures held while using a smartphone are distinguished between desk postures and lap postures. The FRR was calculated by dividing the maximal muscle activation during the extension phase by average activation during the complete flexion phase. [Results] No significant differences were found in the FRR between desk posture, lap posture, and baseline, though the intensity of the neck pain increased in the lap posture. [Conclusion] The FRR could be a significant criterion of neuromuscular impairment in chronic neck pain or lumbar pain patients, but it is impossible to distinguish neck pain that is caused by performing task for a short time. Prolonged lap posture might cause neck pain, so the use of smartphones for a long time in this posture should be avoided.Key words: Smartphone, Cervical flexion-relaxation ratio, Electromyography     

Activation of the gluteus maximus,gluteus medius and tensor fascia lata muscles during hip internal and external rotation exercises at three hip flexion postures

BackgroundHip internal and external rotation exercises are usually performed in clinical practice. However, given the synergies required to stabilize the hip in the frontal plane, it is not clear how the activation of target muscles will differ between the two exercise directions.ObjectiveI) Compare the activation of the upper and lower fibers of gluteus maximus (GMax), gluteus medius (GMed) and tensor fascia lata muscles between the hip internal and external rotation exercises; ii) Compare the maximal isometric force between hip internal and external rotation exercises and; iii) Assess the effect of varying hip flexion angles on muscle activation and maximal isometric force.Study designA cross sectional study.MethodsElectromyography and force production of twenty-one participants were measured during maximum isometric hip internal and external rotation in three postures: 0°, 45° and 90° of hip flexion.ResultsMANOVA results showed a larger activation of the GMed, tensor fascia lata and upper GMax (p < .001) for hip internal rotation compared to external rotation regardless of hip flexion angle. For the lower GMax, the same was observed when the hip was kept at 90° of flexion. Maximal isometric force during hip external rotation was greater than during hip internal rotation at 0° posture, and lower at 90° posture (p < .001).ConclusionThe gluteus and the tensor fascia lata muscles were substantially recruited during the hip internal rotation exercise, and barely recruited during the hip external rotation exercise. Hip flexion influences the myoeletric activity and isometric force production during the internal rotation exercise.     

An ultrasonographic investigation of deep neck flexor muscles cross-sectional area in forward and normal head posture

Background

As one of the most common work-related musculoskeletal disorders and postural deviations, forward head posture (FHP), is considered to lead to muscle imbalance.