• Journal of the Korean Society of Physical Medicine
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• v.9 no.1
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• pp.125-132
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• 2014

PURPOSE: This study aims to determine the optimal knee joint angle and hip joint angle for minimizing the cervical muscle tension and maximizing the muscle activity of the trunk during the bridging exercise for trunk stabilization. METHODS: The bridging exercise in this study included seven forms of exercise: having a knee joint flexion angle of $120^{\circ}$, $90^{\circ}$, $60^{\circ}$, $45^{\circ}$ and hip joint abduction angle of $15^{\circ}$, $10^{\circ}$, $5^{\circ}$. The posture of the bridging exercise was as follows. To prevent the increase of hyper lumbar lordosis during the bridging exercise, the exercise was practiced after maintaining the lumbar neutral position through the pelvic posterior tilting exercise. RESULTS: The abduction angles did not result in statistically significant effects on the cervical erector, external oblique, rectus abdominis and erector spinae muscles. However, in relation to the knee joint angles, during the bridging exercise, statistically significant results were exhibited. CONCLUSION: The knee joint angle affected the muscle activity of the neck muscle. The greater the knee joint angle, the lower the load placed on the neck muscle. In contrast, the load increased as the knee joint angle decreased. In addition, the muscle activity of the neck muscle and trunk muscle increased as the knee joint angle decreased.

• 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.17 no.3
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• pp.379-389
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• 2019

Purpose: This study examined the effects of wheelchair handle directions on the trunk muscle activity of adult males when climbing ramps. It also evaluated the wheelchair attendant's physical discomfort during tasks. Methods: Healthy males aged over 20 years were chosen and the direction of wheelchair handle grip was randomly selected. The grips included a general grip with ulnar deviation, a medial grip with wrist pronation, and a neutral grip with a neutral wrist. The trunk muscle activity was measured using surface electromyography. Furthermore, the physical discomfort of wheelchair attendants was subjectively evaluated using the Borg CR-10 Scale, which rates the perceived exertion. In addition, the SPSS 18.0 program was used perform repeated measure ANOVA to compare muscle activity and subjective discomfort during the interventions. The contrast test was also conducted with a significance level (α) of 0.05. Results: There was significant difference between the general grip and the medial grip in the rhomboid major muscle and the lumbar erector spinae muscle (p<0.05). In addition, there was significant difference between the general grip and the neutral grip in the rhomboid major muscle and the lumbar erector spinae muscle (p<0.05). Further, there was significant difference between the general grip and the neutral grip in subjective discomfort (p<0.05). Conclusion: In this study, adult male trunk muscle activity and subjective discomfort were lowest when using the neutral grip while climbing ramps. Accordingly, we suggest that neutral grips will help improve the function of the musculoskeletal system and reduce the subjective discomfort by putting less strain on the trunk muscles and maximizing efficiency with less force.

• Journal of Korean Neurosurgical Society
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• v.59 no.3
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• pp.276-281
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• 2016

Objective : Although trunk muscles in the lumbar spine preserve spinal stability and motility, little is known about the relationship between trunk muscles and spinal fusion rate. The aim of the present study is to evaluate the correlation between trunk muscles cross sectional area (MCSA) and fusion rate after posterior lumbar interbody fusion (PLIF) using stand-alone cages. Methods : A total of 89 adult patients with degenerative lumbar disease who were performed PLIF using stand-alone cages at L4-5 were included in this study. The cross-sectional area of the psoas major (PS), erector spinae (ES), and multifidus (MF) muscles were quantitatively evaluated by preoperative lumbar magnetic resonance imaging at the L3-4, L4-5, and L5-S1 segments, and bone union was evaluated by dynamic lumbar X-rays. Results : Of the 89 patients, 68 had bone union and 21 did not. The MCSAs at all segments in both groups were significantly different (p<0.05) for the PS muscle, those at L3-4 and L4-5 segments between groups were significantly different (p=0.048, 0.021) for the ES and MF muscles. In the multivariate analysis, differences in the PS MCSA at the L4-5 and L5-S1 segments remained significant (p=0.048, 0.043 and odds ratio=1.098, 1.169). In comparison analysis between male and female patients, most MCSAs of male patients were larger than female's. Fusion rates of male patients (80.7%) were higher than female's (68.8%), too. Conclusion : For PLIF surgery, PS muscle function appears to be an important factor for bone union and preventing back muscle injury is essential for better fusion rate.

• Journal of Korean Institute of Industrial Engineers
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• v.33 no.1
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• pp.44-51
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• 2007

The purpose of this study was to identify the relationship between the cumulative fatigue of trunk muscles andthe period of recovery time during repetitive lifting and lowering tasks with symmetric and asymmetric postures.Ten subjects participated in the experiment. Subjects had 1, 2, 3, 4 and 5 minutes recovery time respectivelywhile they were performing the lifting and lowering task repeatedly for 3 minutes with the weight equivalent to25% level of MVC. EMG signals from ten trunk muscles were collected and the fatigue level was analyzedquantitatively. In results, the local muscle fatigue was no longer accumulated when 5 minutes recovery time wasgiven in symmetric position. For asymmetric position, it took longer minutes to prevent the fatigue accumul-ation. Different trunk muscles indicated slightly different recovery patterns in terms of MPF (Mean Powerfrequency) value.This result would help ergonomist design the length of recovery time to control the cumulative fatigue of trunkmuscles in industry with repetitive lifting and lowering task.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1244-1252
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• 2011

This study was to investigate the effect of intensive trunk-pelvic stabilizing training using sling exercise on trunk muscle activity and balance in patients with hemiplegia. Twenty hemiplegic patients(6 month ${\leq}$, 1 years >) participated were divided into two groups randomly. Control group(n=10) had only general rehabilitation training and experimental group(n=10) had both the general rehabilitation training and intensive trunk-pelvic stabilizing training using sling. They were treated for 30 min./5 times/4 week. I measured ability of trunk control, muscle activity, and balance which were done before and after the intensive training using sling. In significant difference after training, show a significant difference in TIS(p<.001), in particular static(p<.05), dynamic(p<.01), coordination(p<.05) and muscle activity of RA(p<.001), EO(p<.001), ES(p<.001), Multifidus(p<.05), FMA(Balance)(p<.01), and static(p<.001) & dynamic(p<.001) balance ability on MTD-Balance system. As this study proved effective therapeutic exercise of trunk muscle activity and balance ability on intensive trunk-pelvic stabilizing training using sling, it could identify importance of trunk-pelvic stabilizing and control on balance.

• The Journal of Korean Physical Therapy
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• v.27 no.5
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• pp.281-286
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• 2015

Purpose: The study was to determine whether mechanical horseback-riding training according to velocity may improve trunk muscles thickness in healthy adults. Methods: Twenty healthy adults participated in this study. The subjects were divided into 2 groups as follows: 10 subjects in high velocity mechanical horseback-riding training (MHRT) and 10 subjects in low velocity MHRT. Subjects in all groups performed a total of 18 sessions 3 times a day for 20 minutes and this experiment lasted for 6 weeks. Mann-Whitney and Wilcoxon Signed Rank test were used in analysis the results of trunk muscle thickness. Ultrasonography was performed to evaluate for thickness of rectus abdominis (RA), external oblique (EO), internal oblique (IO), transverse abdominis (TrA), erector spine (ES), and multifidus (MF) in trunk muscles. Results: Results on the changes of EO, IO, and ES of high velocity MHRT showed a significant increase after 6 weeks (p<0.05). Regarding the changes of EO, IO, ES, TrA, and MF of low velocity MHRT, a significant increase was observed after 6 weeks (p<0.05). The differences in change of trunk muscle thickness before training, after 6-week training between groups, TrA and MF of low velocity MHRT were significantly higher (p<0.05). Conclusion: Based on the results of the current study, the velocity of MHRT was shown to affect change of trunk muscle thickness in healthy adults. In particular, low velocity MHRT may serve as a useful method to provide for TrA, MF thickness improvement related to trunk stabilizers.

• Journal of the Ergonomics Society of Korea
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• v.33 no.2
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• pp.143-153
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• 2014

Objective: The aim of this study is to investigate the effects of trunk-forearm supported sitting on trunk flexion angle, trunk extensor fatigue and seat contact pressure. Background: The relationship between sitting posture and musculoskeletal disorders of the trunk extensor fatigue and seat contact pressure has been documented. The trunk-forearm support type ergonomic chair was devised from the fact that trunk-forearm support has been reported to reduce trunk extensor activity and discomfort. Method: Using three different sitting postures, upright ($P_1$), trunk-forearm supported ($P_2$) and normal sitting ($P_3$), six healthy subjects participated in the study. Motion capture system was used to collect head and trunk flexion angle, and surface electromyography (sEMG) was used to collect myoelectric signal of upper trapezius, lower trapezius, erector spinae, multifidus, and pressure mat system was used to measure seat contact pressure. Results: When trunk and forearm were supported by the ergonomic chair, higher head flexion angle showed upright > trunk-forearm supported > normal in order, and muscle fatigue showed less than upright and normal sitting. Mean seat contact pressure decreased 19% than upright sitting. But muscle fatigue was not affected by each condition. Conclusion: Trunk-forearm supported sitting of the ergonomic chair showed positive effect in respect of trunk and head flexion angle, trunk extensor fatigue, seat contact pressure. To acquire comprehensive understanding of the effectiveness of the ergonomic chair, further studies such as anatomical effects from measurement of external applied loading effect to the body from interface pressure analysis are required. Application: The results of the publishing trend analysis might help physiological effects of trunk-forearm support type chair.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.12 no.2
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• pp.33-41
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• 2006

This study planed to analyze durability of effect and result that the Medx and Sling exercise gets to the strength of lumbar extensors. 15 patients who had enforce the minimal invasive lumbar surgery were executed 3 times per week for 8 weeks. The purpose of this study was to identify the influence of the mixed exercises of the Medx and Sling program on lumbar trunk muscles and to present basic data for the proper exercise prescription for lumbar patients. The results were as follows: 1) Left: Patients by lumbar hernia operation of trunk muscle strength by Sling-exercise: 0, 45, 90, 135, 180 (degree) treatment periods (P<0.05). 2) Right: Patients by lumbar hernia operation of trunk muscle strength by Sling-Exercise: 0, 45, 90, 135, 180 (degree) treatment periods (P<0.05). Medx treatment, a muscle strengthening lumbar extension exercise program, was now being used at local hospitals. In addition, Sling exercise, which is designed to develop lumbar muscle by way of reducing gravity in a new way so that it can accelerate the growth of muscles and ligaments in-depth in the patients, also has begun to be introduced gradually. In this study, therefore, the new mixed program (Sling and Medx training)can used as an exercise program that can reduce pain and increase lumbar muscles, not only for disk disease patients but also for all those who have undergone surgery or who haven't undergone surgery, who have chronic pain, and it also can be utilized as basic data for the new method of exercise.

• Journal of the Korean Society of Physical Medicine
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• v.4 no.4
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• pp.221-229
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• 2009

Purpose : The purpose of this study was to assess the effect of bridging stabilization exercises of trunk muscles activity on a Swiss ball according to change of position. Methods：30 healthy university students volunteered to participate in this study. Subjects were required to complete following three exercise positions. Exercise position 1; Supine bridge with Swiss ball, Exercise position 2; Side bridge with Swiss ball, Exercise position 3; Prone bridge with Swiss ball. Surface electromyography from selected trunk muscles was normalized to maximum voluntary isometric contraction. Results : A repeated measures of ANOVA with Duncan's correction was used to determine the influence of exercise type on muscle activity for rectus abdominis, external oblique, erector spinae. The erector spinae of exercise position 1 showed significantly higher muscle activity than exercise position 2, 3(p<.05). The external oblique of exercise position 2, 3 showed significantly higher muscle activity than exercise position 1(p<.05). The rectus abdominis of exercise position 3 showed significantly higher muscle activity than exercise position 1, 2(p<.05) Conclusion： These results indicate that muscle activity can be influenced by addition of a Swiss ball in bridging exercises. It is recommend to use a Swiss ball for trunk stabilization exercise.