• Journal of Mechanical Science and Technology
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• v.17 no.1
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• pp.32-39
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• 2003

In this study we examined connections between vertebral motion and patterns of muscle activation during voluntary head tracking movements. A Rhesus (Maraca mulatta) monkey was trained to produce sinusoidal tracking movements of the head in the sagittal plane while seated. Radio-opaque markers were placed in the cervical vertebrae, and intramuscular patch electrodes were implanted to record from eight neck muscles. Videofluoroscopic images of cervical vertebral motion, and EMG (electromyographic) responses were simultaneously re-corded. Experimental results demonstrated that head and vertebrae moved synchronously and that motion occurred primarily at skull-C$_1$, C$\_$6/-C$\_$7/ and Csub 7/-C$_1$. Our findings illustrate that although the biomechanical constraints of each species may limit the number of solutions available, it is the task requirements that appear to govern CNS (central nervous system) selection of movement behaviors.

• The Journal of Korean Physical Therapy
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• v.13 no.3
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• pp.777-789
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• 2001

The purpose of this study was to investigate the possibility of using surface electromyographic signals as a measure of muscle fatigue during the wheelchair propulsion. Subjects performed wheelchair exercise tests on a motor-driven treadmill with a constant-velocity of 1.25 m/sec. During each test, the raw EMC signals were acquired from the surface electrodes attached on the belly of five muscle groups: biceps brachii, pectoralis major. deltoid, triceps brachii, and trapezius. The median power frequency(MPF), and the root mean square(RMS) amplitude were calculated for each cyclic contraction in order to quantify muscle fatigue. During the wheelchair propulsion, the MPF decreased and the RMS increased in the trapezius and deltoid. However, the decreasing MPF and the increasing RMS also fluctuated severly during dynamic muscle contractions. Therefore, the MPF and RMS values should be estimated with well-designed methods and used with caution to quantify muscle fatigue during wheelchair propulsion.

• Journal of Oral Medicine and Pain
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• v.25 no.1
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• pp.99-108
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• 2000

This study was performed to investigate the effect of suboccipital stretch on the head and neck posture and the electromyographic(EMG) activity of some cervical muscles. For this study, 39 patients with temporomandibular disorders(TMD) and 34 dental students without any signs and symptoms in the masticatory system were selected as the patients group and as the normal group, respectively. Head position by goniometer CROM$^{(R)}$(Performance attainment, St. Paul, USA), EMG activity by BioEMG$^{(R)}$(Bioresearch Inc., Milwaukee, USA), and craniocervical posture by cephaloradiography were observed in both natural head posture(NHP) and head posture with suboccipital stretch(tuck posture) abtained from slight posteroinferior finger pressure on the chin. Variables measured on the cephaloradiograph were SN angle, atlas angle, CVT angle, occiput-atlas and atlas-axis distance, and pharyngeal width. The data obtained were analysed by SPSS windows program and the results of this study were as follows : 1. In the sagittal plane, degree of anterior rotation of the head by suboccipital stretch was 6.3 in the patients group, and 6.2 in the normal group, respectively. So there was no significant difference between the two groups for degree of anterior rotation, but the position of the head in the patients group were more posteriorly extended than in the normal group in both NHP and tuck posture. 2. EMG activity of the stemocleidomastoideus in the patients group, and that of the upper trapezius and the sternocleidomastoideus in the normal group were increased by suboccipital stretch. The range of EMG activity, however, in these cervical muscles were 1.6 -2.3)u.V. 3. Cephalometric variables such as SN angle, atlas angle, CVT angle, occiput-atlas and atlas-axis distance except pharyngeal width were generally increased by suboccipital stretch. There was some difference, however, in results between the two groups. Atlas angle was not changed in the patients group whereas CVT angle was not changed in the normal group. 4. The distance from subocciput to spinous process of axis was significantly increased as much as 3.0mm in the patients group, and 3.7mm in the normal group by suboccipital stretch.

• Korean Journal of Applied Biomechanics
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• v.18 no.4
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• pp.171-177
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• 2008

This work intends to investigate the effects of pedaling directions on the muscle actions during the bicycle's uphill propulsion. A test rig was developed that consists of a bicyle with a special planetary geartrain, a height-adjustable treadmill, a rear-wheel support and a magnetic brake. A three-dimensional motion analysis was performed for measuring kinematic characteristics of the forward backward pedaling and the electromygraphy(EMG) measurements were simultaneously performed for estimating the muscle actions of the leg. In this work, four muscles are considered including Gastrocnemius muscle(GM), Vastus lateralis(VL), Tibialis anterior(TA) and Soleus(SOL) while the uphill slope is varied from $0^{\circ}$ to $6^{\circ}$. Raw EMG signals were first processed through the root-mean-square(RMS) averaging and then ensemble curves were derived by averaging the EMG RMS envelopes over 50 consecutive cycles. Results show that both the kinemactic characteristics and the muscle actions are significantly affected by the pedaling direction. The crank speed of the forward pedaling is higher but the difference in speed is reduced as the slope is increased. The ensemble curves of the :ac signals clearly exhibit some differences in their patterns, peak values and the corresponding locations with respect to the crank angle. The peak values of most EMG signals are higher for the forward pedaling regardless of the slope magnitude. However, the averages of the EMG signals are not observed to have a similar relationship with the pedaling direction, which seems to be affected by several factors such as less experience of the participants' backward pedaling. inappropriate bicycle design for the backward pedaling. These limitations will be further considered in future work.

• Physical Therapy Korea
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• v.5 no.4
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• pp.41-51
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• 1998

The right hip abductor musculature has been reported to demonstrate "stretch weakness" attributable to chronic elongation imposed by standing posture common to right-handed healthy persons. Kendall and associates have described the concept of "stretch weakness",. The purpose of this study was to assess isometric hip abduction torque and surface electromyographic activity (using MYOMED 432) in a sample of 40 healthy right-handed persons (20 male, 20 female), all of whom agreed to participate in the study, and compare side difference in the hip abductor musculature. In order to assure the statistical significance of the results, the paired t test was applied at the .05 level of significance. The results were as follows: 1) The difference in apparent leg length of right and left legs was significant at the .05 level. 2) There was a significant difference between right and left pelvic height (standing position) at the 05 level measurements, and scapula height at the .05 level. 3) Power measurements and action potentials of right hip abductor were greater than the left hip abductor regardless of the range of joint motion (inner range, outer range) 4) The difference in muscle power and action potentials according to inner or outer range of both hip abductor were significant at the .05 level. 5) In supine during active left hip abduction, the appearance of action potentials in the right hip abductors is indicative of contra-lateral effect (p<.05) These results suggest: In healthy right-handed persons, the apparent leg length on the right is longer than on the left, and pelvic height is elevated on the right side. Muscle those and muscle action potentials of the right hip abductor are higher than those of the left hip abductor in the lengthened position. Therefore, the results in this study are contrary to Kendall's. This type of study should be carried out in many physical therapy departments.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.3
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• pp.328-342
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• 1999

This study was performed to investigate the factors related to tooth wear. For this study, 78 patients with temporomandibular disorders and 76 dental students without any signs and symptoms of temporomandibular disorders were selected as the patients group and as the normal group, respectively. Preferred chewing side, Angle's classification, lateral guidance pattern, head and shoulder posture were observed clinically. Electromyographic activity of anterior temporalis and masseter muscle were recorded with $BioEMG^{(R)}$ and occlusal status were recorded with $T-Scan^{(R)}$. Wear facet area of each tooth was measured from working model of upper arch corresponding to the occlusal status from T-Scan. Wear facet area were measured with planimeter in $mm^2$. Total area were divided into incisal, canine, posterior tooth area. Anterior wearfacet area was incisor area plus canine area, and unilateral area was anterior area plus posterior area. The data collected were analyzed by SAS statistical program and the results of this study were as follows: 1. There was no significant difference between the two groups in total werafacet area, and male subjects showed tendency to have larger area in the normal group but female subjects showed tendency vice versa. 2. There was no significant difference related to preferred chewing side and Angle's classification, however some difference was observed by lateral guidance pattern. Anterior wear facet area in subjects of canine guidance was the largest in the three subgroups. 3. Subjects with head tilting to right side had larger posterior and total area, and subjects with higher shoulder in right side had larger canine and anterior area than any other subgrous. 4. Electromyographic activity of masseter muscle was more correlated with wear facet area than anterior temporalis muscle, and tooth contact number and force were significantly correlated with wear facet area, but the most important factor affecting tooth attrition was age.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.3
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• pp.259-266
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• 2005

The function of the masseter and anterior temporal muscles was assessed by electromyography in 30 patients with mandibular prognathism (20 patients with facial asymmetry and 10 patients without facial asymmetry) before orthognathic surgery and 4weeks afterwards. Electromyogram(EMG) recordings were made during resting, clenching and swallowing. We compared with right-left difference of this recording and asymmetry index before and after orthognathic surgery. The result of this study was as follows. 1. There was no significant right-left difference in muscle activities of masticatory muscles both asymmetric groups and controls and many variable change after orthognathic surgery.(P>0.05) 2. The mean electric activity of the masticatory muscles was found to have decreased during more clenching than resting, but there was no statistically significant difference because of individual difference of measuring values.(P>0.05) 3. The asymmetry index of masticatory muscles in asymmetric groups was significantly greater during clenching compared with controls.(P<0.05) In conclusion, no right-left difference of muscle activities was found in patients with facial asymmetry before orthognathic surgery and 4weeks afterwards. Not only muscular functioning but also many other factors, such as occlusion, temporomandibular joint disorder and trauma, probably affect facial asymmetry and will be analyzed in future studies. And we will need long term follow-up after orthognathic surgery.

• The korean journal of orthodontics
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• v.22 no.2 s.37
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• pp.389-412
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• 1992

Along with form and function relationship of craniofacial growth comes a concern for the masticatory muscles with postnormal occlusion. It is the aim of this study to grope the certain differences upon the electromyographic activities of the masticatory muscles between normal occlusion and class II malocclusion during the varieties of oral functions. 26 persons of normal occlusion whose mean age were 18.9-25.6 years and another 26 persons of class II malocclusion whose mean age were 19.0-28.9 years served for this study. The electromyographic recordings processed by $Medelec^{\circledR}$ MS 25 EMG apparatus were taken from the anterior and posterior temporal, and anterior and posterior masseter muscles of both sides, and suprahyoid muscles as well. Analyses of the data toward such specific activities as mandibular rest, maximal biting, chewing gums and swallowing peanuts turned out the following summary and conclusions. 1. The maximal mean amplitude of the posterior temporalis showed significant augmentation in class II malocclusion, however the anterior temporalis, posterior masseter, and suprahyoid muscles manifested meaningful diminutions. 2. Stronger posterior temporalis and weaker anterior masseter and suprahyoid muscles were arranged in maximal biting with parameters of maximal mean amplitude. 3. The anterior temporalis of working side expressed smaller maximal mean amplitude in class II malocclusion. Significant swelling in duration were shown at anterior and posterior temporalis of working side, and posterior temporalis of balancing side in class II malocclusion, and marked reduction at anterior masseter of balancing side and posterior masseter of working side as well. The lessened latency were expressed at anterior masseter of working side, and anterior and posterior masseter of balancing side. Class II malocclusion group had significant prolongation of silent period duration. Mean silent period duration of 10.75 msec in normal occlusion and 24.37 msec in class II malocclusion were calculated. 4. Significant augmentations of maximal mean amplitude while swallowing peanuts were yielded at right anterior temporalis and posterior temporalis of both sides, however left anterior masseter and right posterior masseter showed diminution. No significant differences in duration showed at every muscle examined in class II malocclusion group.5. Weaker masseter and stronger temporalis were suggested as characteristics of class II malocclusion.

• Physical Therapy Korea
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• v.11 no.3
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• pp.43-50
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• 2004

This study was designed to determine the effects of different widths in the base of support (BOS) on trunk and lower extremity muscle activation during upper extremity exercise. Twenty-seven healthy male subjects volunteered for this study. Exercises were performed for a total of 10 trials with a load of 10 repetitions maximum (10 RM) for each of the various widths of BOS (10 cm, 32 cm, 45 cm). The width of a BOS is the distance between each medial malleoli when a subject was in a comfortable standing position. Electromyography was used to determine muscle activation. Surface bipolar electrodes were applied over the tibialis anterior, medial gastrocnemius, biceps femoris, rectus femoris, gluteus maximus, upper rectus abdominis, and elector spinae muscle. Electromyographic (EMG) root mean square (RMS) signal intensity was normalized to 5 seconds of EMG obtained with a maximal voluntary isometric contraction (MVIC). The data were analyzed by atwo-factor analysis of variance (ANOVA) with repeated-measures ($3{\times}7$) and Bonferroni post hoc test. The results were as follows: (1) There were significant differences in the width of the BOS (p=.006). (2) The post hoc test showed significant differences with the BOS between 10 cm and 32 cm, between 10 cm and 45 cm and between 32 cm and 35 cm (p=.008, p=.003, p=.011). (3) There was no interaction with the BOS and muscle. (p=.438) There were no significant differences in the muscle activation (p=.215).

• Journal of the Korean Applied Science and Technology
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• v.35 no.1
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• pp.36-42
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• 2018

This study was to investigate the difference of muscle activities in trunk, upper arm, and shoulder during push-up exercise based on 3 types of different arm position(posterior position, PP; normal position, NP; and anterior position, AP) and to provide effective push-up arm position for each muscle development. Fifteen healthy males(age, $21.5{\pm}0.5years$; height, $172.7{\pm}1.0cm$; body mass, $70.5{\pm}1.3kg$; shoulder width, $42.3{\pm}0.6cm$; and BMI, $23.6{\pm}0.5kg/m^2$) participated in this study. PP, NP, and AP of the arm were used to conduct push-up exercise and 8 muscles(deltoideus p. acromialis: DA; pectoralis minor: PMI; pectoralis major: PMA; serratus anterior: SA; biceps brachii: BB; triceps brachii: TB; latissimus dorsi: LD; and infraspinatus: IS) of right side were selected to measure muscle activities. Total 9 counts of push-up exercise were conducted and EMG data signals of 5-time(from $3^{th}$ to $7^{th}$) push-up movement were used for measuring muscle activities. PP push-up exercise showed that there was a significantly higher muscle activity of DA, PMI, PMA, SA, BB, LD, and IS(p<.05) and AP push-up exercise showed a significantly higher TB activity(p<.05). It would be suggested that different arm position evokes various muscle activities when conducting push-up exercise. PP would be the best push-up arm position for inducing various trunk, upper arm, and shoulder muscle activities compared to NP and AP.