• Journal of The Korean Society of Integrative Medicine
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• v.3 no.1
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• pp.81-90
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• 2015

Purpose: The purpose of this study was to investigate any visible difference in shoulder stability muscle activity along the bending angle($70^{\circ}$, $90^{\circ}$, $110^{\circ}$) to perform the open kinetic chain(OKC) and closed kinetic chain(CKC) exercise. Method: This study was performed on normal 20 males subjects. Exercise was carried out in two ways OKC and CKC. Shoulder stability muscles are examined activity in the bending angles. In the OKC and CKC exercise to subjects with stretched out waist straightened, and than push forward the shoulder. Muscular activation was examined using the WEMG-8. Result: The results of this study were as follows. 1. Only in the trapezius muscle, it showed specific interaction between exercise methods and angles. When it comes to muscle activity, there was no significant difference in all muscles except for the anterior fibers of the deltoid muscle during both CKC and OKC exercise. 2. The average value of maximum muscle activity was significantly increased with increasing order of angles. But in CKC exercise, the muscle activity of infraspinatus tended to decrease with increasing angles. Conclusion: To summarize the research results, the muscle activity in upper fibers of the trapezius, anterior fibers of the deltoid, and serratus anterior was significantly different depending on the angle of the shoulder in both CKC and OKC exercise.

• Physical Therapy Korea
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• v.11 no.1
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• pp.45-52
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• 2004

Altered scapular kinematics in the scapular joint is commonly believed to be a factor contributing to trunk posture. The purpose of this study was to analyze the muscle activity with several changes of the shoulder angle. Tests were performed on 10 male subjects by repeated measures. Each subject was measured while sitting in both erect and slouched trunk positions. In each sitting posture, a three-dimensional motion analysis measurement was used to measure thoracic angle and shoulder abduction angle. Measurements were taken with the shoulder abdcution angle at $0^{\circ}$, $30^{\circ}$, $60^{\circ}$, $90^{\circ}$, $120^{\circ}$, and $150^{\circ}$. By using surface Electromyography (EMG) electrodes, we recorded the activity of the upper trapezius, middle trapezius, lower trapezius, middle deltoid, and serratus anterior muscle while the subject held a 4 kg weight at each angle. The mean of root mean square (RMS) of EMG activity was calculated. The middle trapezius, lower trapezius, and middle deltoid muscle activity showed significantly higher results but serratus anterior muscle activity showed significantly lower results (p<.05). With the shoulder angle increased, the muscle activity was also significantly increased (p<.05). In conclusion, the thoracic spine posture significantly affects the scapular muscle during scapular plane abduction, and the slouched posture is associated with increased trapezius muscle activity and with decreased serratus anterior muscle activity.

• PNF and Movement
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• v.13 no.1
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• pp.1-7
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• 2015

Purpose: This study aimed to examine the activity of the shoulder flexor and extensor when hold-relax and contraction-relax techniques were applied with shoulder joint flexion. Methods: The subjects of this study were 15 healthy women. With the shoulder joint flexion at $0^{\circ}$ and $90^{\circ}$, hold-relax and contraction-relax techniques were applied for the same submaximal resistance to measure the activities of the deltoid muscle anterior fiber, deltoid muscle posterior fiber, pectoralis major fiber, and latissimus dorsi muscle with surface electromyography. An independent t-test was conducted in order to compare activities of each muscle according to the two techniques. Results: When the hold-relax and contraction-relax techniques were applied with the shoulder joint flexion at $0^{\circ}$, the activities of the shoulder flexor and extensor were not significantly different, but the activity of the flexor was higher when the contraction-relax technique was applied than when the hold-relax technique was applied. When the hold-relax and contraction-relax techniques were applied with the shoulder joint flexed at $90^{\circ}$, the activities of the shoulder flexor and extensor were not significantly different, but the activity of the extensor was relatively higher than when the flexor was at $0^{\circ}$ Conclusion: When the hold-relax and contraction-relax techniques were applied with the shoulder joint flexion at $0^{\circ}$, the activities of the shoulder flexor and extensor were not significantly different, but the activity of the flexor was higher when the contraction-relax technique was applied than when the hold-relax technique was applied. When the hold-relax and contraction-relax techniques were applied with the shoulder joint flexed at $90^{\circ}$, the activities of the shoulder flexor and extensor were not significantly different, but the activity of the extensor was relatively higher than when the flexor was at $0^{\circ}$.

• The Journal of Korean Physical Therapy
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• v.33 no.3
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• pp.148-154
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• 2021

Purpose: This study covered the effect of shoulder stabilization exercise on muscle activity, postural alignment and self-efficacy of the elderly people with round shoulders by visiting village hall in rural area. Methods: 40 elderly people with round shoulders were recruited for this study (experimental group: 20 subjects and control group: 20 subjects). The experimental group was asked to perform shoulder stabilization exercise 60 minutes per one time for 8 weeks and three times in a week and the control group was asked to receive education related to pain management for the initial one time. Before and after the experiment, we measured the subjects' muscle activity of upper trapezius, serratus anterior, infraspinatus, pectoralis major and the lower trapezius, then postural alignment of craniovertebral angle and round shoulder posture. In addition, self-efficacy is measured through the questionnaire. Results: Compared to the control group, the experimental group showed significant differences in the muscle activity of all muscles, posture alignment of the craniovertebral angle. round shoulder posture, and improvement of self-efficacy. Conclusion: We found that shoulder stabilization exercise is effective in muscle activity, postural alignment and self-efficacy of the elderly people through visit-rehabilitation service. This study can be used for improving the physical and mental abilities through active visit-rehabilitation service for areas where have poor medical benefits. It is considered that systematic visit rehabilitation service should have institutional framework ultimately.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.4
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• pp.199-207
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• 2022

Purpose : The purpose of this study is to investigate the effect of shoulder stabilization exercise accompanied by application of a pelvic compression belt on the muscle activity, pain and function of the muscles around the shoulder in subjects with round shoulders. Methods : For the study method, 28 students who were enrolled in K University with a distance of 1 cm or more between the clavicle of the peak and the outer ear path were selected through GPS 400 global postural analysis system measurement. The subjects were randomly assigned to 14 participants in the group wearing a pelvic compression belt and 14 patients in the group not wearing a pelvic compression belt. In all subjects, the muscle activities of the middle trapezius, lower trapezius, and serratus anterior muscles and the shoulder pain disorder index (SPADI) were measured. The intervention was performed 3 times a week for 4 weeks, and the applied intervention was push-up plus and modified prone cobra exercise. The muscle activities of the middle trapezius, lower trapezius, and serratus anterior muscles and SPADI score were compared using dependent t test before and after intervention. Results : In this study, both groups showed that the muscle activity of the middle trapezius, lower trapezius, and serratus anterior significantly increased after the intervention compared to before the intervention. On the other hand, SPADI showed no significant difference. Conclusion : The results of this study showed that muscle activity in the peri-shoulder joint was increased after push-up plus and modified prone cobra exercise in both groups, regardless of whether pelvic compression was applied or not. Therefore, it was found that shoulder stabilization exercise using the pelvic compression belt also contributed to the enhancement of muscle activity in the joints around the shoulder.

• The Journal of Korean Physical Therapy
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• v.25 no.4
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• pp.217-223
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• 2013

Purpose: This study was to investigate whether the two different head postures, natural and ideal head posture, affect head/shoulder posture and muscle activity. Methods: Thirty healthy subjects with the forward head and round shoulder posture were participated in this study. This study utilized a within-subjects design with subjects being positioned into two sitting positions: natural head posture (NHP) and ideal head posture (IHP). Forward head angle (FHA) and forward shoulder angle (FSA) of each subject were measured for assessing the head/shoulder posture and muscle activities of upper trapezius (UT), lower trapezius (LT), and serratus anterior (SA) during the forward overhead reaching. Results: There were significant increases in both FHA and FSA after taking IHP, which showed greater angles than in taking NHP. In change of muscle activities, there were significant decreases in both LT and SA after taking IHP, which showed lower activities than in taking a NHP, whereas there was no significant change in UT. Conclusion: These findings demonstrate that postural alterations associated with forward head and rounded shoulder postures could alter scapular kinetics and muscle activity during the forward overhead reaching.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.1
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• pp.61-66
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• 2017

PURPOSE: The purpose of this study was to investigate the effects of isometric upper limb contraction on the trunk and lower extremity muscles during the sit-to-stand activity in elderly females. METHODS: Eighteen healthy elderly females performed three directional isometric upper extremity contractions (flexion, extension, and horizontal abduction movements) using an elastic band during sit-to-stand activity. Electromyography signals were collected from the internal oblique, erector spinae, rectus femoris, and biceps femoris muscles. RESULTS: Internal oblique activity was greater in bilateral shoulder flexion and bilateral shoulder horizontal abduction than in neutral position (p<.05). Erector spinae and rectus femoris muscle activities in bilateral shoulder flexion was greater than in neutral position and bilateral shoulder extension (p<.05). Biceps femoris activity was significantly greater in bilateral shoulder flexion than in bilateral shoulder extension and horizontal abduction, and in neutral position compared to bilateral shoulder extension (p<.05). CONCLUSION: These results suggest that incorporating isometric upper limb contraction may be beneficial for enhancing the contribution of trunk and lower extremity muscle activities to trunk stabilization during sit-to-stand activity. Therefore, isometric upper limb contraction during sit-to-stand tasks, especially in flexion, may be used to elicit contraction of the lumbopelvic region muscles within a tolerable range, for developing endurance and strength in the elderly.

• PNF and Movement
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• v.14 no.2
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• pp.131-137
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• 2016

Purpose: The purpose of this study was to compare muscle activities in the frontal plane and scapular plane of the middle fiber and lower fiber of the trapezius muscle at different shoulder abduction angles. Methods: Twenty male and female students in their 20s participated in this study. Each subject maintained shoulder abduction at $75^{\circ}$, $90^{\circ}$, $125^{\circ}$, and $160^{\circ}$ in a standing position and repeated motions three times each in the frontal plane and the scapular plane. While maintaining the motions for 10 seconds in each posture, surface electromyography (EMG) was used to measure muscle activity of the middle fiber and lower fiber of the trapezius muscle. The collected EMG data were normalized using maximal voluntary isometric contraction (MVIC). Differences in muscle activity of the middle fiber and lower fiber of the trapezius muscles according to the angles at each plane were statistically processed using repeated measured analysis of variance, and an independent t-test was used to examine the differences between the two planes at each angle. Results: Muscle activity of the middle and lower trapezius during shoulder abduction in the frontal plane and scapular plane significantly increased as the angles increased (p<.05). However, muscle activity of the middle trapezius was significantly lower in the scapular plane than in the frontal plane for all shoulder abduction angles (p<.05). Conclusion: The results of this study suggest that during shoulder abduction, angles should be different according to the goals, and for training during an acute phase or early phase for functional recovery, it is more efficient to perform the training in the scapular plane than in the frontal plane.

• Journal of International Academy of Physical Therapy Research
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• v.12 no.2
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• pp.2308-2313
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• 2021

Background: Although the scapular posterior tilt movement could facilitate the lower trapezius (LT) muscle activity, no study identified the effects of the scapular posterior tilt movement on the selective activation of the LT muscle during prone shoulder extension. Objectives: To examine the influences of additional scapular posterior tilt on electromyography (EMG) of the upper trapezius (UT) and the LT muscles during prone shoulder extension. Design: Cross-sectional study. Methods: There were 15 asymptomatic male participants in this study who performed prone shoulder extension with and without scapular posterior tilt movements. For the scapular posterior tilt movements, participants performed visual biofeedback training for scapular movement using motion sensor. During the exercises, the EMG activity of the UT and LT was recorded using surface EMG system. Results: The EMG activity of the LT significantly increased during prone shoulder extension with scapular posterior tilt compared to that of general prone shoulder extension, whereas that of the UT was not significantly different between the two exercises. Moreover, scapular posterior tilt application significantly decreased UT/LT muscle activity ratio. Conclusion: Scapular posterior tilt movement may be emphasized during exercise when facilitating LT muscle activation.

• Journal of the Ergonomics Society of Korea
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• v.34 no.4
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• pp.313-326
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• 2015

Objective: The objective of this research is to quantitatively analyze muscle activities of arm and shoulder, according to direction in various types of one-handed manual material handling, based on surface electromyography. Background: Workers in industrial sites frequently carry out one-handed manual material handling using arm and shoulder muscles. Therefore, chronic load and accumulated fatigue occur to arm and shoulder muscles, which becomes a main cause of upper arm and shoulder musculoskeletal disorders. The shoulder muscles have widely range of motion, and complex interactions take place among various muscles including rotator cuff muscles. In this regard, research on interactions among should muscles, according to such various dynamic motions, is required. Method: Ten male subjects in their 20s participated in this research. This research considered upward, downward, leftward, rightward, forward and backward directions and fourteen muscles around arm and shoulder (biceps brachii and trapezius, etc.) as independent variables. The mean muscle activity was set as the dependent variable. This research extracted $4^{th}{\sim}7^{th}$ repetition signals according to ten times of repetitive muscle contraction, and analyzed the muscle activity concerned using the envelope detection technique. Results: The mean muscle activity of upward direction was analyzed highly statistically significant. The reason is that the effect of gravity works to arm and shoulder muscles. Also, it is conjectured that deformation of coracoacromial ligament was caused, and its contact pressure increased, due mainly to the shoulder flexion, and therefore load was analyzed high. Muscle activity was analyzed significantly low, according to concentric ballistic motion used in the concentric contraction phase by storing elastic energy in the eccentric contraction phase with a motion to bring the weight to the front of subject's body as to downward, leftward and backward directions. Because, elbow joint's flexion-extension motions mainly occurred, biceps brachii was analyzed high muscle activity as the prime mover. Conclusion: The information on the quantitative load of muscles can be applied to ergonomic work design for one-handed manual material handling to minimize muscle load. Application: This research has effectively identified muscle activity according to dynamic contraction by applying an envelope detection technique. The results can be used for ergonomic work design to minimize muscle load during the one-handed manual material handling, according to each direction. The research results are expected to be used for musculoskeletal disorder prevention and physiotherapy in the rehabilitation medical field, based on the muscle load of arm and shoulder in various directions.