• PNF and Movement
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• v.20 no.3
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• pp.331-340
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• 2022

Purpose: Thisstudy aimed to identify the effect of varying the expansibility of elastic tape on the onset time of muscle contraction during neck extension for forward head posture syndrome. Methods: Forty-five young adults with forward head posture syndrome volunteered to participate and were randomly assigned to one of three groups according to the expansibility of the elastic tape (25%, 50%, 75%). The onset time of muscle contraction for the neck extensor during neck extension was measured using an electromyographic system (Free EMG, BTS, Italy). Multivariate analysis of variance was employed to determine the effect of different expansibilities of elastic tape on the onset time of muscle contraction during neck extension for forward head posture syndrome. When there was a statistically significant difference by MANOVA, Scheffe was used as a post-hoc test. The level of significance was set at α=0.05. Results: In the comparison of the onset time of muscle contraction of varying elastic tape expansibilities and measurement times, there was a significant difference between the groups (Lt. UT, Lt. SCM, Rt. SCM) (p < 0.05), but there was no significant difference in the interaction between the measurement time and the group, between the measurement time (p > 0.05). Conclusion: In the neck extension, 75% of the tape extensibility in the Lt. UT and both SCM shortened the muscle contraction onset time.

• The Korean Journal of Physiology
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• v.26 no.2
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• pp.151-157
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• 1992

In urethane anesthetized cats, each vestibular semicircular canal nerve was electrically stimulated, and reflex responses of the cervical extensor and flexor (the splenius capitis and sternomastoid muscles) were recorded by means of electromyography. Stimulation of a unilateral (anterior, horizontal or posterior) canal nerve elicited excitation of the contralateral cervical muscles and inhibition of the ipsilateral ones; during the canal nerve stimulation, the two muscles in one side of the neck revealed synergistic responses. Based on these experimental results, we formulated a diagram showing the functional connections between the vestibular semicircular canals and the cervical muscles in the vestibulocollic reflex.

• Journal of the Korea Society of Computer and Information
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• v.26 no.6
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• pp.129-135
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• 2021

The purpose of this study was to investigate the relationship of the head posture with the tone and stiffness of the cervical extensor muscles. Eighty adults in their twenties were chosen as subjects, and the tone and stiffness of the cervical extensor muscles were measured, with their usual head posture in the sagittal plane. For the measured head posture, the craniovertebral angle (CVA), craniorotation angle (CRA), and forward shoulder angle (FSA) were analyzed using Image J. It was observed that the tone and stiffness of the upper trapezius muscle increased significantly with a decrease in the CVA as well as with an increase in the CRA (p < 0.05). As a result of further classification into the normal and forward head postures based on the CVA of the subjects, the forward head posture was characterized by a significant increase in the tone and stiffness of the upper trapezius muscle (p<.05). The results of this study are expected to be used as basic data for the evaluation of the forward head posture and posture education in clinical practice.

• The Korean Journal of Physiology
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• v.24 no.1
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• pp.103-113
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• 1990

The role of cervical proprioceptors in the control of body posture was studied in bilaterally labyrinth-ectomized, decerebrate cats. The animals were suspended on hip pins with the neck extended horizontally. With this placement the EMG activities of extensor and flexor muscles of the upper extremities were observed by means of sinusoidal head rotator. The rotator can induce two kinds of neck movement: The one is 'pitch' which describes a rotatory neck motion to transverse axis of the body and mainly occurs at skull-C1 (atlantooccipital) joint and the other is 'roll', side-to-side relation of the neck to longitudinal axis, whose center is C1-C2 (atlanto-axial) joint. The following results were obtained. 1) Responses of EMG activity were closely dependent on the rotatory range of the neck. And the EMG activity was not changed during sustained neck torsion, eliciting a typical tonic neck reflex. 2) On pitching movement, the head-up rotation produced the excitation of bilateral triceps muscles, whereas the head-down rotation produced the inhibition. And the response of bilateral biceps muscles was the opposite to that of triceps. 3) On rolling movement, the side-up rotation of the head produced the excitation of ipsilateral triceps muscles and the inhibition of contralateral ones. And the response of biceps muscles was the opposite to that of triceps. 4) The minimum requirement of motion to evoke EMG activities in the upper extremities was $3.2^{\circ}{\sim}12.5^{\circ}$. These results have shown that the cervical proprioceptors produce tonic discharge on the upper brachial muscles, regulate the EMG activities of those muscles, and are very sensitive to neck rotation. And it can be stated that the cervical proprioceptors may play an important role in the control of body posture and movement.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.2
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• pp.137-144
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• 2019

PURPOSE: The continued use of smartphones has resulted in an abnormal body posture and neck alignment changes. Maintaining this posture for a long time weakens the flexor muscles in the neck and shortens the extensor muscles in the neck. This study examined the correlation between the suboccipital muscle tension and deep neck flexor muscle physical endurance according to the craniovertebral angles. METHODS: The craniovertebral angle, tension of the suboccipital muscle and endurance of the deep neck flexor muscle were measured in 58 healthy 20-year-old male and female college students. The tension of suboccipital muscle and endurance of the deep neck flexor muscle were then divided according to the body mass index (BMI). Their correlation with the craniovertebral angle was then examined. Each parameter was measured three times to determine the interrater reliability. RESULTS: The craniovertebral angle and suboccipital muscle tension showed differed significantly. On the other hand, the craniovertebral angle and deep neck flexor muscle physical endurance showed no significant differences. CONCLUSION: The results show that the craniovertebral angle and deep neck flexor muscle physical endurance were not correlated, but a smaller craniovertebral angle resulted in a higher suboccipital muscle tension.

• 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.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.10 no.1
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• pp.30-36
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• 2003

Purpose: The strength of hand grip, low back muscles and knee joint muscles were measured and then compared to the bone mineral density (BMD) of each forearm bones (including ulna and radius), lumbar spine, and femur in young women in order to identify the relationship between muscle strength and bone mineral density. Method: The BMD was measured with a Dual Energy X-ray Absorptiometry and muscle strength was measured with a handgrip dynamometer and a Cybex Norm. Data were analyzed with frequencies, percentages, means, and Pearson correlation coefficients. Result: 1) Higher grip strength correlated positively with higher BMD in the forearm (r=.246, p=.007), higher low back extensor strength with higher BMD in the femur (neck, trochanter and Ward's triangle)($r=.323{\sim}.226$, $p=.003{\sim}.043$) and higher strength in the knee joint extensor with higher BMD in the lumbar spine (r=.227, p=.041), femur neck, and femur trochanter significantly ($r=.295{\sim}.226$, $p=.007{\sim}.043$). There was no significant correlation between the strength of low back extensors and BMD in the lumbar spine, now with strength of knee joint flexor and the BMD in the femur. 2) The muscle strength of each part of the body had significant positive correlations to each other part ($r=.255{\sim}.728$ $p=.021{\sim}.000$) Conclusion: The results of this study showed that with the development of a muscle there was an increased BMD of the corresponding part, and the BMD of each part was influenced by adjacent muscles. To promote the health of bones, it is important to strengthen the muscles of related bones, based on balanced development of all muscles.

• Journal of the Ergonomics Society of Korea
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• v.34 no.1
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• pp.11-18
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• 2015

Objective: The aim of this study was to understand the effects of phone weight on the typing performance and muscle recruitment in the neck and upper extremity while typing a text message with dominant hand. The iPhone4 and iPhone5 were compared due to their 28-gram differences in weight. Background: Too much use of a cellular phone can lead the musculoskeletal disorders in the upper extremity. Phone makers tend to make their new models bigger, lighter, faster and smarter. Method: Fourteen healthy volunteers without any history of neuromuscular disorders or ongoing pain who used their smartphone more than one year were recruited. A 112g phone (iPhone5) and a 142g phone (iPhone4) were used for typing the lyric of the Korean national anthem with their dominant hand. Typing duration, the typing error, the perceived fatigue, and preference was investigated. Muscle recruitment and the resting gap of neck (middle trapezius and levator scapula), shoulder (infraspinatus and mid deltoid), elbow (biceps brachii and brachioradialis), thumb (extensor and abductor policis brevis) were collected using surface electromyography. Typing error was counted and typing speed was calculated in characters per min. The data were analyzed using a paired t-test and chi-square (${\chi}^2$) analysis for the effects of phone weight on the typing performance parameters and muscle recruitment. Results: Typing text message with iPhone5 took longer but had less muscle recruitment in brachioradialis, and extensor policis brevis muscles. Lighter weight of iPhone5 made biceps brachii to rest less without increasing the mean %EMG. Conclusion/Application: Findings of this study can be valuable information for phone designers to develop more productive device and for smartphone users to prevent the musculoskeletal disorders in the upper extremities.

• Journal of The Korean Society of Integrative Medicine
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• v.4 no.4
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• pp.83-90
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• 2016

Purpose : Recommended posture according to the location of operating teeth have been standardized in dental clinic to prevent musculoskeletal disorder. However, clinicians do not comply with this rule in many cases. This study investigated the effects of operating posture on cranio-cervical range of motion (CROM) and muscles activity of neck and upper extremity. Methods : Sixteen healthy dental hygiene students were participated. During operating posture (3 recommended and 3 experimental postures which were set front, side, back, respectively), CROM in the fronal and sagittal plane were measured by Cervical Range of Motion Instrument and muscle activities of Sternocleidomastoid, upper trapezius, middle deltoid, extensor carpi radialis, brachioradialis, and abductor pollicis brevis were measured by Pocket EMG system. Result : CROM were significantly decreased in recommended posture in comparison with experimental posture (p<.05). In addition, muscle activity of middle deltoid was significantly decreased in recommended front posture. Moreover, brachioradialis and extensor carpi radialis showed the same result in recommended back posture (p<.05). Conclusion : Recommended posture is close to neutral posture and to reduce muscle fatigue and overuse, which may considered as a preventing musculoskeletal disorder and partially explain its efficacy in dental clinic.

• Journal of Korean Medicine Rehabilitation
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• v.26 no.1
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• pp.63-77
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• 2016

Objectives The objective of this study is to interpretate Yangsaeng-Doinbub presented in [Jebyungwonhuron Huhrobyungjehu] in a modern kinesiologic approach. Methods Based on the interpretation of [Jebyungwonhuron Huhrobyungjehu] and implementation of its kinesiology, this study presents similar kinesiologies and their purposed, with the reference to various documents on modern kinesiology. Results 1) Exercises in Yangsaeng-Doinbub presented in [Jebyungwonhuron Huhrobyungjehu], which are similar to resistance exercise, can be used for isometric exercise of knee joint extensor and cervical extensor. 2) Exercises in Yangsaeng-Doinbub presented in [Jebyungwonhuron Huhrobyungjehu], which are similar to stretching exercise, has its purpose to stretch semitendinosus m., semimembranous m., gastrocnemius m., quadriceps femoris m., upper trapezius m., levator scapulae m., serratus m., and splenius capitis m. 3) Exercises in Yangsaeng-Doinbub presented in [Jebyungwonhuron Huhrobyungjehu], which are similar to active exercise, can be used for strengthen quadriceps femoris m.. 4) Yangsaeng-Doinibub also describes breathing methods, which help normalization of breathing exercised and increase the efficiency of spine and joint exercises. Conclusions The modern interpretation on kinesiology of Yangsaeng-Doinbub presented in [Jebyungwonhuron Huhrobyungjehu] leads to a conclusion that Yangsaeng-Doinbub consists of various exercises for knee joint, neck and upper extremity.