• Journal of the Ergonomics Society of Korea
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• v.26 no.4
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• pp.25-31
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• 2007

The purpose of this study was to investigate the strength and endurance of the deep neck flexor muscles in individuals with work-related neck pain. Subjects consisted of two groups: twenty industrial workers with neck pain and twenty age-matched healthy subjects. To evaluate the strength and endurance of deep cervical flexors, maximum voluntary contractile strength (MVCS) and a sustained time at sub-maximal voluntary contractile strength (SMVCS) (80% and 50% of MVCS) were measured using a pressure biofeedback unit and a stop watch in supine. The MVCS of deep neck flexor muscles was 29.67${\pm}$4.56 in neck pain group and 54.27${\pm}$6.78㎜Hg in normal group. The sustained time at 80% SMVCS was 12.42${\pm}$2.64 seconds and 55.12${\pm}$12.76 seconds in the groups with and without neck pain. The sustained time at 50% SMVCS was 25.40±5.88 seconds and 109.70${\pm}$31.50 seconds in the groups with and without neck pain. The difference of the lower jaw position was 16.75${\pm}$3.57㎜ and 23.03${\pm}$2.51㎜. The MVCS, endurance at the two sub-maximal levels and the difference of the lower jaw position were significantly greater in the group without neck pain than with neck pain (p$<$0.05). The findings indicate that the maximal strength and endurance of the deep neck flexors were decreased in the workers with neck pain compared to those without neck pain. Therefore, it is necessary to include strengthening and endurance exercises of the deep neck flexor muscles in therapeutic program of work-related musculoskeletal disorders involving neck pain.

• The Korean Journal of Pain
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• v.37 no.2
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• pp.164-177
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• 2024

Background: Neck and jaw pain is common and is associated with jaw functional limitations, postural stability, muscular endurance, and proprioception. This study aimed to investigate the effect of jaw and neck pain on cranio-cervico-mandibular functions and postural stability in patients with temporomandibular joint disorders (TMJDs). Methods: Fifty-two patients with TMJDs were included and assessed using Fonseca's Questionnaire and the Helkimo Clinical Dysfunction Index. An isometric strength test was performed for the TMJ depressor and cervical muscles. The TMJ position sense (TMJPS) test and cervical joint position error test (CJPET) were employed for proprioception. Total sway degree was obtained for the assessment of postural stability. Deep neck flexor endurance (DNFE) was assessed using the craniocervical flexion test. The mandibular function impairment questionnaire (MFIQ) was employed to assess mandibular function, and the craniovertebral angle (CVA) was measured for forward head posture. Results: Jaw and neck pain negatively affected CVA (R² = 0.130), TMJPS (R² = 0.286), DNFE (R² = 0.355), TMJ depressor (R² = 0.145), cervical flexor (R² = 0.144), and extensor (R² = 0.148) muscle strength. Jaw and neck pain also positively affected CJPET for flexion (R² = 0.116) and extension (R² = 0.146), as well as total sway degree (R² = 0.128) and MFIQ (R² = 0.230). Conclusions: Patients with painful TMJDs, could have impaired muscle strength and proprioception of the TMJ and cervical region. The jaw and neck pain could also affect postural stability, and the endurance of deep neck flexors as well as mandibular functions in TMJDs.

• Clinics in Shoulder and Elbow
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• v.27 no.1
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• pp.52-58
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• 2024

Background: Deficiency in scapular muscle endurance (SME) is a risk factor for rotator-cuff-related shoulder pain (RCRSP). However, the exact relationship among SME, pain, and functionality remains unclear. This study aims to compare SME, pain, and functionality in RCRSP patients to those in age-sex-matched healthy controls. Methods: Twenty-three patients with RCRSP and 23 age-sex matched healthy controls were included in the study. SME was measured using a 1-kg dynamometer. Self-reported pain level was assessed using a visual analog scale. The Functional Impairment Test-Hand, Neck, Shoulder, and Arm (FIT-HaNSA) was also used to assess functional impairment. Results: The control group had higher SME and total FIT-HaNSA scores than the patient group (P<0.05). There was a statistically significant and positive correlation between SME and FIT-HaNSA scores in both groups (P<0.05). Conclusions: SME was affected by RCRSP. Pain and functional impairment were correlated with low SME.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.07a
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• pp.305-307
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• 2023

본 연구는 전방머리자세 대학생을 대상으로 목뼈안정화운동이 머리뼈척추각, 깊은목굽힘근 지구력 및 뒤통수밑근 근긴장도의 변화를 알아보고자 하였다. 이 연구 결과 CSEG에서 CVA, DNFET에서 유의하게 증가하였으며 뒤통수근 근긴장도에서는 경직도에서만 유의하게 감소하였다. 목뼈 안정화운동은 목뼈의 중립자세를 유지하면서 깊은목 굽힘근 활성화되고 근지구력이 향상되었으며, 턱을 당기는 동작으로 튀통수근의 경직이 감소한 것으로 생각된다. 또한 지구력 증가시키고 근 긴장도에 감소는 통증을 조절함에 있어서도 도움이 될 것이다. 따라서 목뼈안정화운동은 깊은목굽힘근과 뒤통수근의 개선을 위한 중재방법임을 확인할 수 있었으며, 전방머리자세 예방하기 위해 필요할 것으로 생각된다.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.25 no.1
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• pp.71-76
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• 2019

Background: An 8-year-old girl had severe neck pain and stiffness after trauma. CT scan showed atlantoaxial rotatory subluxation (AARS). She had conservative treatment because she did not have neurological symptoms and spinal basilar artery dysfunction. Conservative therapy was halter traction twice for 4 weeks. However, pain and stiffness persisted. She had been recommended to have surgery from her physician, but she received manual therapy for non-surgical procedures. Methods: The joint mobilization, muscle energy technique, motor control exercise, and deep neck flexor (DNF) endurance exercise were applied as manual therapy and 10 session for 2weeks. Results: Clinical outcomes were measured at initial baseline, after 2 weeks, and after 6weeks. Active range of motion was completely restored after 6weeks and numeric pain rating scale was completely reduced after 2 weeks. The strength of neck flexor muscle recovered to normal after 2 weeks, and the DNF endurance was improved to 25 seconds after 2 weeks and to 42 seconds after 6weeks. Motor control capacity recovered to 30 ㎜Hg after 2 weeks. Conclusions: This case report describes the immediate and short-term clinical outcomes for a patient presenting with symptoms of neck pain following AARS. Clinical rationale and patient preference aided the decision to incorporate manual therapy as a treatment for this patient. Manual therapy has shown a successful recovery in AARS patients, more research is needed to validate the inference of this case report.

• Physical Therapy Korea
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• v.28 no.1
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• pp.18-26
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• 2021

Previous studies have reported that deep neck flexor (DNF) exercise can improve neck problems, including neck pain, forward head posture, and headache, by targeting the deep and superficial muscles of the neck. Despite the prevailing opinion across studies, the benefits of DNF can vary according to the type of neck problems and the outcome measures adopted, ranging from positive outcomes to non-significant benefits. A meta-analysis was conducted in this study to assess conclusive evidence of the impact of DNF exercise on individuals with neck problems. We used PUBMED, MEDLINE, NDSL, EMBASE, and Web of Science to search for primary studies and the key terms used in these searches were "forward head posture (FHP)," "biofeedback," "pressure biofeedback unit," "stabilizer," "headache," and "neck pain." Twenty-four eligible studies were included in this meta-analysis and were coded according to the type of neck problems and outcome measures described, such as pain, endurance, involvement of neck muscle, craniovertebral angle (CVA), neck disability index (NDI), cervical range of motion (CROM), radiographs of the neck, posture, strength, endurance, and headache disability index. The overall effect size of the DNF exercise was 0.489. The effect sizes of the neck problems were 0.556 (neck pain), -1.278 (FHP), 0.176 (headache), and 1.850 (mix). The effect sizes of outcome measures were 1.045 (pain), 0.966 (endurance), 0.894 (deep neck flexor), 0.608 (superficial neck flexor), 0.487 (CVA), 0.409 (NDI), and 0.252 (CROM). According to the results of this study, DNF exercise can effectively reduce neck pain. Thus, DNF exercise is highly recommend as an effective exercise method for individuals suffering from neck pain.

• Physical Therapy Rehabilitation Science
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• v.7 no.4
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• pp.186-190
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• 2018

Objective: Deep neck flexor muscle endurance (DNFET) is important to cervical pain patients. However, there is no normative data of the DNFET hold time of Korean university students. The purpose of this study was to provide normative data and the reliability of the DNFET times of Korean university students and to compare the DNFET hold times between male and female subjects. Design: Cross-sectional study. Methods: The participants included 39 male and 39 female students with no cervical pain. Each DNFET was measured while the subjects kept their chin tucked in while in a supine (hook-lying) position and with the head lifted 2.5 cm off the bed. The DNFET was conducted on each subject twice and the mean values were obtained. After each measurement, the participants rested for 5 minutes. Inter-rater reliability was measured by intraclass correlation coefficient (ICC) by three separate evaluators. Results: The inter-rater reliability was good, showing an ICC (2,3) value = 0.785 (95% confidence interval, 0.370-0.942). The DNFET time scores for men and women were $25.14{\pm}9.96$ seconds and $15.23{\pm}6.10$ seconds, respectively, in which the time scores of the men were significantly longer compared to women (p<0.05). Conclusions: Asymptomatic men displayed higher DNFET scores than women. This study can help clinicians test cervical function of patients and set an interventional goal. These findings serve as a basis that insists Korean women to increase their amount of physical activity.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.2
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• pp.189-195
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• 2019

Purpose : The purpose of this study was to investigate the effects of chin tuck exercise (CTE) on the craniovertebral angle (CVA), strength and endurance of deep cervical flexor (DCF) muscles in subjects with forward head posture(FHP). This study was performed on 30 subjects with FHP. Method : Thirty subjects were divided into two groups; modified CTE (n=15), conventional CTE (n=15). Both of the group performed the exercise 4 times a week for 6 weeks. The subjects performed CTE in two different methods; modified CTE, with device designed that help keep cervical lordois curve, and coventional CTE, without using device. The CVA was measured using Image software version. A pressure biofeedback unit was used to measure the strength and endurance of the DCF muscles. The data was analyzed by the paired t-test for comparing before and after changes of variables in each group and the independent t-test for comparing the between groups. Result : There was statistically significant difference of before and after strength and endurance of DCF muscles in modified CTE (p<0.05). There was statistically significant difference of before and after only endurance of DCF muscles in conventional CTE (p<0.05). There was statistically significant difference of between the two group in strength of DCF muscles (p<0.05). Conclusion : Muscle strength to stabilize the spine plays an important role in maintaining a good posture. Therefore, we suggest that the application of CTE with a device designed to maintain the lordotic curvature in the neck is likely to yield better outcomes in FHP subjects in future studies.

• Sleep Medicine and Psychophysiology
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• v.12 no.2
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• pp.105-110
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• 2005

The pathogenesis and mechanism of obstructive sleep apnea (OSA) has been under investigation for over 25 years, but its etiology and mechanism remains elusive. Skeletal (maxillary and/or mandibular hypoplasia or retrodisplacement, inferior displacement of hyoid) and soft tissue (increased volume of soft tissue, adenotonsillar hypertrophy, macroglossia, thickened lateral pharyngeal walls) factors, pharyngeal compliance (increased), pharyngeal muscle factors (impaired strength and endurance of pharyngeal dilators and fixators), sensory factors (impaired mechanoreceptor sensitivity, impaired pharyngeal dilator reflexes), respiratory control system factors (unstable respiratory control) and so on facilitate collapse upper airway. Therefore, OSA may be a heterogeneous disorder, rather than a single disease entity and various pathogenic factors contribute to the OSA varies person to person. As a result, patients may respond to different therapeutic approaches based on the predominant abnormality leading to the sleep-disordered breathing.

• Physical Therapy Korea
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• v.29 no.3
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• pp.180-186
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• 2022

Background: The craniocervical flexion test (CCFT) was developed for the activation and endurance of deep cervical flexors. However, the muscle thickness and muscle thickness changing ratio of the sternocleidomastoid (SCM) and deep cervical flexor (DCF) muscles in subjects with and without forward head posture (FHP) have not been reported. Objects: To determine the difference in thickness of the SCM and DCF muscles and the difference in the muscle thickness changing ratio between SCM, DCF, and DCF/SCM 20 mmHg and DCF/SCM 30 mmHg between subjects with and without FHP. Methods: Thirty subjects with and without FHP were enrolled. The muscle thickness of the SCM and DCF was measured when maintained at a baseline pressure of 20 mmHg and a maximum pressure of 30 mmHg using a pressure biofeedback unit during the CCFT. Ultrasonography was used to capture images of SCM and DCF muscle thickness during the CCFT, which was calculated using the picture archiving and communication system (PACS). Results: We observed a significant difference within the pressure main effect between SCM and DCF at a baseline pressure of 20 mmHg and a maximum pressure of 30 mmHg (p < 0.05). However, there was no significant difference in the muscle thickness and muscle thickness changing ratio for SCM and DCF during CCFT between subjects with and without FHP. Conclusion: There was no significant difference in the muscle thickness recruitment pattern during CCFT in posture changes between subjects with and without FHP.