• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.3
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• pp.229-237
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• 2000

According to the functional matrix theory, Delaire proposes that individual occlusal plane was determined by variable effects of teeth, maxilla, mandible, cranium, cranial base and soft tissue matrix including the orofacial musculature. and that there is the ideal occlusal plane determined by the most proper spatial position of maxilla and mandible, functionally and esthetically. This study was designed to find out the relation between Delaire's ideal occlusal plane and muscle activity of masticatory muscles in individuals who have normal maxillo-mandibular relationships. Lateral cephalometric radiographs were taken and his/her individual occlusal plane and ideal occlusal plane were analyzed with Delaire's architectural and structural craniofacial analytic method. For evaluation of muscle activities of masticatory muscles, electromyography of anterior temporal muscle, superficial masseter muscle, and anterior belly of digastric muscle was recorded in fifty Korean normal Angle class I occlusion individuals. According to the average value of ideal occlusal plane, fifty normal Angle class I occlusion individuals were classified into three groups: Ideal occlusal plane group(I group), hyperrotation group(I+ group) and hyporotation group(I- group). The result of this study was as follows: 1. The results of Delaire's architectural and structural craniofacial analysis of lateral cephalography of the fifty Korean normal Angle class I occlusion individuals are that twelve persons(24%) have consistent or parallel with ideal occlusal plane and the average of angular difference was $1.22^{\circ}{\pm}3.69^{\circ}$. 2. There is no significant difference in muscle activities of masticatory muscles during resting(p<0.05), but significant increases of muscle activity of ipsilateral anterior temporal and masseter muscle, contralateral anterior belly of digastric muscle during unilateral chewing and of anterior temporal and masseter muscle during bilateral clenching(p<0.05). 3. To find out the effect of the angular difference between Delaire's ideal occlusal plane and real occlusal plane to muscle activity, muscle activities of masticatory muscles were compared with three groups in each other; I group, I+ group and I- group. The results were no significant differences during resting, unilateral chewing and bilateral clenching.(p>0.05) 4. Although there is no significant differences of masticatory muscle activities among the three groups, the fact that increasing tendency of masseter muscle activity of ideal occlusal plane group(I+) than those of any other groups(I+ and I-) during bilateral clenching was noted. There is only the implication that occlusal plane makes some effects on masticatory muscle activities, espacially that of masseter muscle during bilateral clenching. In conclusion, the hypothesis that occlusal plane is one of the factors which affect the muscle activities of masticatory muscles and that anyone whose occlusal plane consistent with Delaire's ideal occlusal plane has an extraordinary functional advantage in masticatory muscle function cannot be proven with electromyography methods.

• Physical Therapy Korea
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• v.15 no.2
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• pp.11-19
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• 2008

Studies of attentional focus effects, have shown that the performer's attentional focus plays an important role in the performance and learning of motor tasks. We examined the influence of attentional focus on the performance of dual tasks (a postural task and a suprapostural task) and used electromyography (EMG) to examine whether the differences between external and internal focus were also manifest at the neuromuscular level. The subjects (n=40) stood on a balance board (postural task) and held a bar horizontally (suprapostural task). All of the subjects performed under different attentional focus conditions: external (balancer on balance board) or internal (feet) focus on the postural task, and external (balancer on bar) or internal (hand) focus on the suprapostural task. The mean displacement velocity of the bar and the percent reference voluntary contraction (%RVC) of the biceps brachii were reduced when the subjects adopted an external focus on the suprapostural task (p<.05). In addition, the mean displacement velocity of the balance board and %RVC of the tibialis anterior were reduced when the subjects adopted an external focus on the postural task (p<.05). When the subjects adopted an external focus on the suprapostural task, the mean displacement velocity of the balance board and %RVC of the tibialis anterior were also reduced (p<.05). When the subjects' attentional focus was on the postural task, there were no differences in the mean displacement and %RVC of the biceps brachii between attentional focuses. The performance of each task was enhanced when subjects focused on the respective task. The suprapostural task goals had a stronger influence on postural control than vice versa. These results reflect the propensity of the motor system to optimize control processes based on the environmental outcome, or movement effect, that the performer wants to achieve.

• Physical Therapy Korea
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• v.20 no.4
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• pp.1-8
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• 2013

This study analyzes how different knee flexion angles affect the abdominal and pelvic muscle activity during supine bridging. Twenty healthy subjects participated in the study. We used surface electromyography (EMG) to measure how three different knee flexion angles ($100^{\circ}$, $70^{\circ}$, and $40^{\circ}$) affected the activity of the transverse abdominis/internal oblique (TrA/IO), external oblique (EO), biceps femoris (BF), rectus femoris (RF), and gluteus maximus (GM) muscles on the dominant side during supine bridging. The one-way repeated analysis of variance (ANOVA) was used to determine the statistical significance of TrA/IO, EO, BF, RF and GM muscle activity and the GM/BF activity ratio. For the TrA/IO, EO, BF, and GM muscles, supine bridging with different knee flexion angles resulted in significant differences in abdominal and pelvic muscle activity. For the TrA/IO muscles, the post-hoc test demonstrated that muscle activity significantly increased at $40^{\circ}$ compared to $70^{\circ}$; however, there were no significant differences between $100^{\circ}$ and $70^{\circ}$ or $100^{\circ}$ and $40^{\circ}$. For the EO muscle, the post-hoc test demonstrated that muscle activity significantly increased at $40^{\circ}$ compared to $100^{\circ}$ and $70^{\circ}$; no significant difference was observed between angles $100^{\circ}$ and $70^{\circ}$. For the BF muscle, the post-hoc test demonstrated that muscle activity significantly increased according to the knee flexion angle ($40^{\circ}$ > $70^{\circ}$ > $100^{\circ}$). For the GM muscle, the post-hoc test demonstrated that muscle activity significantly increased according to the knee flexion angle ($100^{\circ}$ > $70^{\circ}$ > $40^{\circ}$). However, for the RF muscle, there was no significant difference. Additionally, the GM/BF activity ratio significantly increased according to the knee flexion angle ($100^{\circ}$ > $70^{\circ}$ > $40^{\circ}$). From these results, we can conclude that bridging with a knee flexion of $100^{\circ}$ can strengthen the GM muscle, whereas bridging with a knee flexion of $40^{\circ}$ is recommended to strengthen the IO, EO, and BF muscles. We can also conclude that knee flexion angles should be modified during supine bridging to increase the muscle activity of different target muscles.

• Korean Journal of Applied Biomechanics
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• v.27 no.3
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• pp.197-203
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• 2017

Objective: The purpose of this study was to determine how exercise intensity affects muscle activity and kinematic variables during squat. Method: Fifteen trainers with >5 years of experience were recruited. For the electromyography (EMG) measurements, four surface electrodes were attached to both sides of the lower extremity to monitor the rectus femoris (RF) and biceps femoris. Three digital camcorders were used to obtain three-dimensional kinematics of the body. Each subject performed a squat in different conditions (40% one-repetition maximum [40%1RM], 60%1RM, and 80%1RM). For each trial being analyzed, three critical instants and two phases were identified from the video recording. For each dependent variable, one-way analysis of variance with repeated measures was used to determine whether there were significant differences among the three different conditions (p<.05). When a significant difference was found, post hoc analyses were performed using the contrast procedure. Results: The results showed that the average integrated EMG values of the RF were significantly greater in 80%1RM than in 40%1RM during the extension phase. The temporal parameter was significantly longer in 80%1RM than in 40%1RM and 60%1RM during the extension phase. The joint angle of the knee was significantly greater in 80%1RM than in 40%1RM at flexion. The range of motion of the knee was significantly less in 80%1RM than in 40%1RM and 60%1RM during the flexion phase and the extension phase. The angular velocity was significantly less in 80%1RM than in 40%1RM and 60%1RM during the extension phase. Conclusion: Generally, the increase of muscle strength decreases the pace of motion based on the relation between the strength and speed of muscle. In this study, we also found that the increase of exercise intensity may contribute to the increase of the muscle activity of the RF and the running time in the extension phase during squat motion. We observed that increased exercise intensity may hinder the regulation of the range of motion and joint angle. It is suitable to perform consistent movements while controlling the proper range of motion to maximize the benefit of resistance training.

• Sleep Medicine and Psychophysiology
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• v.9 no.1
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• pp.61-67
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• 2002

Objectives: This study is aimed at measuring psychophysiological responses using a biofeedback system in healthy people to obtain basic normative data for biofeedback research and treatment. Methods: Ninety-six healthy volunteers (55 males and 41 females : average age $30.4{\pm}8.0$) without any history of major medical or psychiatric illnesses participated in this study. Psychophysiological responses were assessed using the ProComp+ and BioGraph program (ver. 2.1) with regard to forearm and frontal electromyography (EMG), electrodermal response (EDR), and skin temperature. They were measured in 3 phases (baseline, stress, and recovery phases), respectively. Beck depression inventory and Spielberger state and trait anxiety inventory were used to measure mood states. We compared psychophysiological responses according to age and gender differences, respectively and examined the relationship between mood states and psychophysiological measures. Results: People in their twenties showed higher EDR levels in the 3 phases than those of other age groups. Female subjects showed higher frontal EMG levels in the 3 phases compared with male subjects. There was no significant correlation between biofeedback measures and mood states in these subjects. Conclusion: We present normative data of psychophysiological responses measured by a biofeedback system in healthy people. These results suggest that gender and age should be considered as important variables in assessing psychophysiological responses using a biofeedback system.

• Physical Therapy Korea
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• v.21 no.3
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• pp.1-10
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• 2014

The aim of this study was to investigate the effect of hip external rotation angle on pelvis and lower limb muscle activity during prone hip extension. Sixteen healthy men were recruited for this study. Each subject performed an abdominal drawing-in maneuver (ADIM) in a prone position, and extended the dominant hip at three different hip external rotation angles ($0^{\circ}$, $20^{\circ}$, $40^{\circ}$) with a $30^{\circ}$ hip joint abduction. Activity of the gluteus maximus (G Max), gluteus medius (G Med), and hamstring (HAM) and the G Max/HAM and G Med/HAM ratios were determined with surface electromyography (EMG). The EMG signal was normalized to 100% maximum voluntary isometric contractions (MVICs) and expressed as %MVIC. Data were analyzed by one-way repeated analysis of variance (alpha level=.05) and the Bonferroni post hoc test. Significant differences in G Max and G Med muscle activity were noted among the three different hip external rotation angles. G Max muscle activity increased significantly at both $40^{\circ}$ (p=.006) and $20^{\circ}$ (p=.010) compared to a $0^{\circ}$ hip external rotation angle. G Med muscle activity increased significantly at $20^{\circ}$ (p=.013) compared to a $40^{\circ}$ hip external rotation angle. The G Max/HAM activity ratio increased significantly at both $40^{\circ}$ (p=.004) and $20^{\circ}$ (p=.014) compared to a $0^{\circ}$ hip external rotation angle. The G Med/HAM activity ratio increased significantly at $20^{\circ}$ (p=.013) compared to a $40^{\circ}$ hip external rotation angle. In conclusion, $40^{\circ}$ and $20^{\circ}$ hip external rotation angles are recommended to increase G Max activity, and $20^{\circ}$ hip external rotation is advocated to enhance G Med muscle activity during prone hip extension with ADIM and $30^{\circ}$ hip abduction in healthy subjects.

• Annals of Clinical Neurophysiology
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• v.9 no.1
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• pp.11-15
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• 2007

Background: The term "overlap syndromes" designates a group of diseases in which polymyositis (PM) or dermatomyositis (DM) is associated with some other disorders of connective tissues. The aim of this study was to delineate the clinical features, laboratory findings, and outcome of treatment of "overlap syndromes" Methods: We analyzed the medical records of 16 patients (PM in 10, DM in 6) with well documented "overlap syndromes" between 1997 and 2004. The diagnosis was made when the criteria for two different disorders were fulfilled. Results: All patients were female. Age of onset ranged from 14 to 52 years (mean 29.8 years) with peak incidence in the third and fourth decades. Systemic lupus erythematosus (SLE) was associated in 10, systemic sclerosis in 7, and rheumatoid arthritis in 3 patients. Four of the patients had two different connective tissue diseases simultaneously. The characteristic clinical features were muscle weakness, arthralgia, Raynaud's phenomenon, and myalgia. In laboratory tests, creatine kinase (CK), lactic dehydrogenase (LDH), and transaminases were usually abnormal. Positive antinuclear antibody (ANA), rheumatoid factor (RF), and cryoglobulin were found in 100%, 69%, and 67% of the patients, respectively. Needle electromyography (EMG) showed abnormal findings compatible with myopathy in 15 patients. The pathology of muscle biopsy from 14 patients revealed findings compatible with inflammatory myopathy. Glucocorticoids were administered to 15 patients. The muscle strength improved in all the treated patients, which was well correlated with repeat CK level and EMG findings. Conclusions: The presence of autoantibodies such as ANA, RF, and cryoglobulin in patients with PM or DM highly suggests the possibility of an overlap syndromes. These syndromes reveal a strong female predominance. The myositis associated with them usually shows a good response to glucocorticoids treatment.

• Physical Therapy Korea
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• v.24 no.2
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• pp.1-8
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• 2017

Background: Individuals with spinal cord injury (SCI) rely on their upper limbs for body-lifting activity (BLA). While studies have examined the electromyography (EMG) and kinematics of the shoulder joints during BLA, no studies have considered foot position during BLA. Objects: This study compared the effects of different foot positions during BLA on the shoulder muscle activities, peak plantar pressure, knee flexion angle, and rating perceived exertion in individuals with SCI. Methods: The study enrolled 13 mens with motor-complete paraplegic SCI, ASIA (American Spinal Injury Association) A or B. All subjects performed BLA with the feet positioned on the wheelchair footrest and on the floor independently. Surface EMG was used to collect data from the latissimus dorsi, pectoralis major, serratus anterior, and triceps brachii. The peak plantar pressure was measured using pedar-X and the knee flexion angle with Image J. Borg's rating perceived exertion scale was used to measure the physical activity intensity level. The paired t-test was used to compare the shoulder muscle activities, peak plantar pressure, knee flexion angle, and rating perceived exertion between the two feet positions during BLA. Results: The activity of the latissimus dorsi, pectoralis major, serratus anterior, and triceps brachii and rating perceived exertion decreased significantly and the peak plantar pressure and knee flexion angle increased significantly when performing BLA with the feet positioned on the wheelchair footrest compared with on the floor (p<.05). Conclusion: These findings suggest that individuals with SCI may perform BLA with the feet positioned on the wheelchair footrest for weight-relief lifting to decrease the shoulder muscle activities and the rating perceived exertion and to increase the peak plantar pressure and the knee flexion angle.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.3
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• pp.219-225
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• 2020

With the aging population, the prevalence of musculoskeletal disorders in the elderly continues to increase. In addition, musculoskeletal disorders are the third most common social and economic loss among occupational illnesses in Workers' compensation insurance benefits as of 2015 standard and are also common among workers. In this study, a vest that can assist in the prevention and treatment of musculoskeletal disorders of the waist was produced, and it is intended to confirm the presence or absence of the effect through experiments. Diseases of the waist are closely related to core muscles. Therefore, the produced vest was made in a form that supports the core muscles. Before and after wearing the vest for effectiveness verification, the While performing 10-times of the Mackenzie exercises, a waist extension exercise, collected the EMG data of the internal oblique, Rectus abdominis, and Erector spinae, which correspond to the core muscles. The collected data were analyzed through the electromyography analysis program RM-3 to obtain RMS values for 10-times measurements of each muscle and to compare the average values. After comparing the data, to verify the significance, the technical statistical value of the measurement result was calculated and the average difference was verified through PASW ver18.0, And the paired t-test is performed on the experimental results to perform statistical processing. and Statistical processing was performed by setting the significance level to α=.05.

• Korean Journal of Clinical Laboratory Science
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• v.50 no.4
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• pp.470-476
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• 2018

Facial motor evoked potential (FMEP) by multi-pulse transcranial electrical stimulation (mpTES) can complement free-running electromyography (EMG) and direct facial nerve stimulation to predict the functional integrity of the facial nerve during cerebello-pontine angle (CPA) tumor surgery. The purpose of this paper is to examine the standardized test methods and the usefulness of FMEP as a predictor of facial nerve function and to minimize the incidence of facial paralysis as an aftereffect of surgery. TES was delivered through electrode Mz (cathode) - M3/M4 (anode), and extracranially direct distal facial muscle excitation was excluded by the absence of single pulse response (SPR) and by longer onset latency (more than 10 ms). FMEP from the orbicularis oris (o.oris) and the mentalis muscle simultaneously can improve the accuracy and success rate compared with FMEP from the o.oris alone. Using the methods described, we can effectively predict facial nerve outcomes immediately after surgery with a reduction of more than 50% of FMEP amplitude as a warning criterion. In conclusion, along with free-running EMG and direct facial nerve stimulation, FMEP is a useful method to reduce the incidence of facial paralysis as a sequela during CPA tumor surgery.