• PNF and Movement
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• 제15권3호
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• pp.381-387
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• 2017

Purpose: Although some studies indicate that the Sorensen test may not be used to examine back muscles such as the erector spinae, alternatives to the back-extension test are rarely suggested. Therefore, the purpose of the present study was to investigate an effective way to stimulate the erector spinae muscles by adding a component of trunk rotation and lateral bending to general back extensions. Methods: A total of 18 healthy, physically active participants performed simple trunk extension, extension with trunk rotation, and extension with lateral bending. Surface electromyography responses of the latissimus dorsi, thoracic, and lumbar levels of the erector spinae; the gluteus maximus; and the biceps femoris muscles were investigated during these 3 conditions of modified back extension tests. Results: The simple trunk extension exercise caused significant increases in activity of the gluteus maximus and biceps femoris muscles as compared to the extension with rotation and lateral bending exercises. The extension with trunk rotation exercise showed significantly greater activation in the thoracic and lumbar levels of the erector spinae and in the latissimus dorsi as compared to the other exercises. The index measuring subjective difficulty was significantly lower in the simple trunk extension exercise as compared to the extension with trunk rotation and extension with lateral bending exercises. Conclusion: The present study suggests that extension with trunk rotation has the advantage of stimulating the para-spinal muscles, while simple trunk extension may not be adequate to selectively simulate the para-spinal muscles but may be appropriate for examining global trunk extensors.

• 대한산업공학회지
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• 제27권4호
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• pp.413-423
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• 2001

Low back disorders (LBDs) are one of the most common and costly work-related musculoskeletal disorders. One of the major possible risk factors of LBDs is to work with static and awkward trunk postures, especially in a complex trunk posture involving flexion, twisting and lateral bending simultaneously. This study is to examine the effect of complex trunk postures on the postural stresses using a psychophysical method. Twelve healthy male students participated in an experiment, in which 29 different trunk postures were evaluated using the magnitude estimation method. The results showed that subjective discomfort significantly increased as the levels of trunk flexion, lateral bending and rotation increased. Significant interaction effects were found between rotation and lateral bending or flexion when the severe lateral bending or rotation were assumed, indicating that simultaneous occurrence of trunk flexion, lateral bending and rotation increases discomfort ratings synergistically. A postural workload evaluation scheme of trunk postures was proposed based on the angular deviation levels from the neutral position. Each trunk posture was assigned numerical stress index depending upon its discomfort rating, which was defined as the ratio of discomfort of a posture to that of its neutral posture. Four qualitative action categories for the stress index were also provided in order to enable practitioners to apply corrective actions appropriately. The proposed scheme is expected to be applied to several field areas for evaluating trunk postural stresses.

• 한국산학기술학회논문지
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• 제13권10호
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• pp.4629-4635
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• 2012

본 연구의 목적은 중량물 들기 작업시 비대칭 무게중심과 상체 옆으로 기울임 여부가 어떻게 L5/S1 주변 허리 근육의 Peak EMG 진폭에 영향을 미치는지를 알아보는 것이다. 요통을 포함한 근골격계질환은 무겁지 않은 물체의 지속적인 반복 취급뿐만 아니라, 일회성의 커다란 부하도 신체 조직의 부담으로 작용하여 발생할 수 있다. 11명의 20대 대학생 남성은 15.8kg의 물체를 들어올리는 Task를 3회 실행하였다. 이 때 대칭 무게중심의 물체를 상체를 기울이지 않고 들어 올리는 경우, 비대칭 무게중심의 물체를 상체를 기울이지 않고 들어 올리는 조건, 그리고 비대칭 무게중심의 물체를 상체를 기울여서 들어 올리는 경우에 따라 6개의 L5/S1 주변의 근육들로부터 Peak EMG 진폭이 수집되어 분석되었다. 결과는 비대칭 무게중심을 지닌 물체 취급시 무게중심에서 먼 쪽의 허리 근육에서 Peak EMG 진폭이 발생하고, 그 진폭의 크기는 대칭 무게중심 물체를 취급하는 경우보다 크게 나타났다. 또한, 비대칭 무게중심의 물체를 취급할 경우 물체나 상체를 물체의 무게중심 방향으로 기울이는 것은 기울이지 않을 때보다 대측성 등근육에서 Peak EMG 진폭 증가시켰다. 이러한 연구 결과는 비대칭 무게중심의 중량물을 들어 올리는 작업에서 요통 발생을 예방하기 위한 행정적인 조치로써 가능하면 상체를 전두면 기준으로 기울이지 않는 작업자 자세 조언이 필요함을 말해준다.

• 대한인간공학회지
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• 제22권4호
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• pp.47-57
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• 2003

This study investigated the recruitment patterns of ten trunk muscles in isometric exertion tasks, focused on the functional roles (agonist or antagonist). Twelve male students performed maximum voluntary isometric exertion tasks towards six directions: flexion/extension, left/right lateral bending, and clockwise/counter-clockwise twisting. EMG signals from ten trunk muscles and exertion forces were collected. Normalized EMG (NEMG) values were calculated at 10, 20, 30, 40, 50, 60, 70, 80, and 90 %MVC. The subjects showed a limited capacity in producing twisting moments, approximately 50% of the extension moment, and 70% of lateral bending moments. EMG activity was dependent on the direction and magnitude of the exertion, and also on the functional role. The mean NEMG of agonist was 0.260 and 0.067 for antagonist. Agonists showed the highest mean NEMG in flexion (0.367), while antagonists showed the highest mean NEMG in twisting clockwise/counter-clockwise (0.090/0.106).

• Journal of Biosystems Engineering
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• 제36권1호
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• pp.58-67
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• 2011

A high prevalence of protected horiculture farmer's work-related musculo-skeletal disorders (MSDs) have been reported in precedent studies. One of the tasks required ergonomic intervention to reduce the musculo-skeletal risks is the task of harvesting. The purpose of this study is to evaluate quantitatively the spinal load of worker harvesting with squatting posture to predict and prevent musculo-skeletal risks. Spinal load in Squatting posture with asymmetric trunk motion were analyzed. Before evaluating spinal load on harvesting worker by bio-mechanical approach, it is needed to validate human model. In this study, ADAMS LifeMOD human model shows satisfactory results, comparing with already validated model's results or measured results. While worker reached arms (20%, 40%, 70% arm reach) with various asymmetric trunk motion (0, 45, 90 degree), their spinal loads (extension, twisting and lateral bending moment) were evaluated. In case of extensor moment at lumbo-sacral joint, the more the arm reach got increased, the moment increased. however, in case of twisting moment and lateral bending moment, the more both arm reach and asymmetric trunk motion got increased, the moment increased significantly. The findings of this study suggest that it need to be determine the spinal load, especially twisting, lateral bending moment in evaluating musculo-skeletal workload in squatting posture.

• 산업경영시스템학회지
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• 제35권3호
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• pp.103-109
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• 2012

The purpose of this paper is to suggest the strategical lifting postures able to alleviate imbalanced EMG amplitude leading to an increase in low back muscle fatigue while lifting asymmetric load dynamically. Eleven male subjects are required to lift symmetrically an external load with 15.8kg and load center of gravity (LCG) deviated 10cm to the right from the floor to the waist height at the speed of about 25cm/sec. The EMG amplitudes on bilateral low back muscles (Longissimus, Iliocostalis, and Multifidus) are recorded during 2sec and analyzed. Independent variables are trunk postures (No bending vs. Bending to the LCG) and feet placements (Parallel vs. Right foot in front of the other vs. Right foot behind the other). Dependent variables are EMG amplitude average on six muscles and the EMG amplitude difference between right and left muscle group. Results indicate the phenomenon showing an amplitude increase in the left muscle group is equal to an decrease in the right one is observed in dynamic as well as static lifts, bending the trunk to the LCG increases amplitude discrepancy more than no trunk bending, and the amplitude discrepancy in one foot ipsilateral to LCG in front of the other foot is lowest among other foot postures. As bilateral EMG amplitude discrepancy increases total low back muscle fatigue, the strategical combination of no trunk bending and one foot close to LCG in front of the other is recommended for preventing elevated incidence of low back pain (LBP).

• PNF and Movement
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• 제7권2호
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• pp.11-20
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• 2009

Purpose : The purpose of this study is to find out which method is efficient to enhance the flexibility of lower back between PNF(Proprioceptive Neuromuscular Facilitation), static and dynamic stretching. Methods : Subjects were 30 young people between the ages 17 and 19. They were randomly divided into three groups; static group(n=10) performed a static stretching, dynamic group(n=10) performed a dynamic stretching, and PNF group(n=10) performed a PNF stretching. Intervention was provided 5 days per week for 4 weeks. For each case, Trunk flexion forward, trunk flexion backward, trunk left lateral bending, trunk right lateral bending, trunk flexion forward a measuring instrument and tapeline were performed to measured the flexibility of lower back at different times(before starting the exercise, after 4 weeks). Results : The results of the study reveal that the lower back flexibility was a statistically significant difference in all groups(p<.05). There was statistically significant difference between PNF group and static group, PNF group and dynamic group. Conclusion : The finding indicated that PNF may be preferred technique for improving flexibility, and that flexibility training results in an increased consistency of flexibility scores.

• 한국치위생학회지
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• 제3권1호
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• pp.73-87
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• 2003

This study was performed on 17 female dental hygienists to find an appropriate method to reduce the hygienists' body discomfort while scaling, and provide a foundation to educate them how 10 posture during the process. To assess the arm abduction, elbow flexion, neck flexion, trunk flexion and trunk lateral bending through Video 2D(two dimensional motion) analysis and assessing the risk through the Action level of RULA(rapid upper limb assessment) checklist, an ergonomic analysis method. Correlation analyses on the posture angles and on body discomfort were performed. ANOVA analysis on scaling treatment position and the scaling treatment region of patients was also performed. The results are as following. 1. 20 analysis while scaling, arm abduction was $40{\sim}79.9^{\circ}$, elbow flexion $20{\sim}110^{\circ}$, neck flexion $50{\sim}100^{\circ}$, trunk flexion $60{\sim}80^{\circ}$, and trunk lateral bending $5{\sim}19.9^{\circ}$. 2. The Action level of RULA was 2. 3 resulted from scores 4 and 5 of group A which includes upper arm, lower ann, wrist, and scores 2 and 4 of group B which includes neck, trunk, legs. It means that the scaling treatment posture causes a high incidence rate of musculoskeletal that an additional investigation and improvement should be followed without hesitation. 3. There were significant differences among the maxilla right, maxilla anterior, maxilla left, mandible left, mandible anterior, and mandible right of a patient of the right and left upper arm, lower arm, neck, trunk, group A, group B, final RULA score while scaling treatment. 4. There were significant differences among the time position of 8, 9, 10, 11, 12, 13 of the right and left upper arm, lower arm, neck, trunk, group A, group B, final RULA score while scaling treatment, 5. As for the body discomfort, neck, right shoulder, left shoulder, right back, right wrist etc. were listed on top. As a conclusion, performing the time position of 12 which shows low right and left final RULA scores is better than the time position of 8 and 10 which show high final RULA scores to reduce the body discomfort while scaling treatment.

• 대한정형도수물리치료학회지
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• 제15권2호
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• pp.63-68
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• 2009

Purpose : The purpose of this study was to investigate the effect of tensor fasciae latae length on the rotation of pelvis during one leg stance. Methods : 41 healthy adults participated in this study. The movement of the pelvis and trunk was measured using 3-dimensional motion analyzer, during one leg stance. The movement of the pelvis and trunk was collected lateral shift, rotation, side bending, and flexion-extension. Tensor fasciae latae length of subjects was measured in sidelying positon with neutral position of hip joint and flexion $90^{\circ}$ of knee. Also, the range of motion of hip exteral and interal rotaion were measured in prone position wih lexion $90^{\circ}$ of knee. The subjects were separated 2 groups that more pelvic rotation group(n=15) and less pelvic rotation group(n=15) according to the degree of pelvic rotation. Results : The more pelvic rotation group was showed significantly higher in the ROM of hip external rotation than less pelvic rotation group(p<0.05). The difference of tensor fasciae latae length not showed significant difference between groups. During one leg stance, The movement of the shifting and flexion-extension of trunk and pelvis were not showed significant difference. But the side bending and the rotation of pelvis and trunk showed significant difference between groups. Conclusion : The difference of tensor fasciae latae length not showed significantly in more pelvic rotation group and less pelvic rotation group. But, this study suggests that the pelvis instability brings the instability of the trunk during one leg stance.

• 한국운동역학회지
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• 제23권4호
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• pp.369-376
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• 2013

The purposes of this study were to assess dynamic stability toward pelvis-spine column distortion during running and to compare the typical three-dimensional angular kinematics of the trunk motion; cervical, thoracic, lumbar segment spine and the pelvis from the multi-segmental spine model between exercise group and non-exercise group. Subjects were recruited as exercise healthy women on regular basis (group A, n=10) and non-exercise idiopathic scoliosis women (group B, n=10). Data was collected by using a vicon motion capture system (MX-T40, UK). The pelvis, spine segments column and lower limbs analysiaed through the 3D kinematic angular ROM pattern. There were significant differences in the time-space variables, the rotation motion of knee joint in lower limbs and the pelvis variables; obliquity in side bending, inter/outer rotation in twisting during running leg movement. There were significant differences in the spinal column that is lower-lumbar, upper-lumbar, upper-thoracic, mid-upper thoracic, mid-lower thoracic, lower thoracic and cervical spine at inclination, lateral bending and twist rotation between group A and group B (<.05, <.01 and <.001). As a results, group B had more restrictive motion than group A in the spinal column and leg movement behaved like a 'shock absorber". And the number of asymmetry index (AI) showed that group B was much lager unbalance than group A. In conclusion, non-exercise group was known to much more influence the dynamic stability of equilibrium for bilateral balance. These finding suggested that dynamic stability aimed at increasing balance of the trunk ROM must involve methods and strategies intended to reduce left/right asymmetry and the exercise injury.