• Journal of the Ergonomics Society of Korea
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• 제34권2호
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• pp.151-165
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• 2015

Objective: This study aims to develop and scientifically investigate the efficacy of the Spine S-curve Reactive Backrest that responds to the spine curvature of the user when seated, and maintains and enhances the natural S-curve of the lower back, thereby helping to relieve fatigue, correct posture and prevent spine deformities. Background: The focus of current development, design guidelines and/or standards for office chairs is mainly placed on the chair's dimensions, incline angle, adjusting features and lumbar support. Research and development was called for developing a chair backrest that maintains and improves the S-curve of the full spine. Method: The Spine S-curve Reactive Backrest was ergonomically designed to maintain correct posture and enhance user comfort. When leaned on, the backrest responds to the user's spine line and the whole lower back sits closely against the backrest, thereby aligning the user's lower back and backrest as one to maintain and improve the natural S-curve formation of the spine. In order to evaluate the efficacy of the newly designed chair (new design) and the comparison target (chair), five male college students of standard body type with normal spine curvature were selected as test subjects, and a motion analyzer and electromyography were utilized to measure S-curve and erector spinae muscle activity when seated. Results: The spine S-curve was better maintained and improved when sitting in the new design than in the comparison chair. Particularly notable was the greater displacement gap of the thoracic spine than the cervical spine, and also that of the lumbar more than the thoracic spine, with the increase of the backrest tilting angle. Furthermore, the electromyogram results showed the new design caused a lower fatigue level of the erector spinae muscles compared to the comparison chair, and also earned a higher preference in the subjective opinion results. Conclusion: The newly designed chair in this study responds to the user's spine curvature and maintains and enhances the lower back's natural S-curve, and thereby relieves fatigue, promotes better posture, and helps to prevent spine deformities better than existing office chairs. There is a need to widely introduce and supply this new design. Application: The new design is applicable to office and student chairs, and is expected to improve concentration and work efficiency.

• Physical Therapy Korea
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• 제19권4호
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• pp.38-45
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• 2012

The aim of this study is to compare the effect of abdominal drawing-in maneuver (ADIM) on lower trapezius (LT), serratus anterior (SA), and erector spinae (ES) muscle activity during arm lifts in prone and standing positions. Twenty healthy subjects were recruited, and NoraxonTeleMyo 2400T was used to collect electromyographic signals from the LT, SA, and ES muscles. A two-way repeated analysis of variance (ANOVA) used a significance level of .05. If a significant interaction was found, pairwise comparisons were performed with a Bonferroni adjustment (.05/4=.013). The results of the study were as follows: 1) In LT, no significant ADIM by position interaction was found ($F_{1,19}$=.356, p=.558). There was a significant main effect for ADIM. LT muscle activity with ADIM was significantly greater compared with muscle activity without ADIM ($F_{1,19}$=82.863, p<.001). There was also a significant main effect for position. LT muscle activity in the prone position was greater compared with muscle activity in the standing position ($F_{1,19}$=116.401, p<.001). 2) In SA, significant ADIM by position interaction was found ($F_{1,19}$=8.687, p=.008). There were significant differences in all pairwise comparisons. The greatest SA muscle activity was observed in the standing position with ADIM. 3) In ES, significant ADIM by position interaction was found ($F_{1,19}$=122.473, p<.001). The lowest ES muscle activity was elicited in the standing position with ADIM. Based on these results, ADIM is advocated in the prone position to increase LT muscle activity. In addition, it is concluded that arm lifts in the standing position with ADIM offer the most favorable combination for reducing ES muscle activity and increasing SA muscle activity.

• Journal of the Ergonomics Society of Korea
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• 제29권3호
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• pp.279-286
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• 2010

The purpose of this study was to compare the electromyographic(EMG) activities of trunk and hip muscles between right and left sides while subjects performed prolonged manual task in asymmetric and symmetric weight-bearing posture. Fifteen healthy male college students were recruited for this study. The subjects were asked to perform bimanual upper extremity task for 6 minutes in two different standing postures. In the symmetric weight-bearing posture, the subjects were standing with evenly distributed body weights to both legs. In the asymmetric weight-bearing posture, the subjects distributed about 90% of their body weight onto their preferred(supporting) leg and 10% of their body weight onto the opposite leg while they were standing. EMG activities of the right and left internal oblique, erector spinae, gluteus maximus, and gluteus medius were measured and normalized as % MVIC. Then the EMG data were statistically analyzed using paired t-tests. The EMG activities of all measured muscles were not significantly different between the right and left side in the symmetrical weight-bearing posture(p>0.05). However, the EMG of the supporting side internal oblique was significantly lower than the opposite side(p<0.05), and the EMG of the erector spinae, gluteus maximus, and gluteus medius were significantly greater on the supporting side(p<0.05). The results of this study support that unbalanced use of right and left muscle possibly causes the changes in muscle length which results in asymmetry of trunk and hip muscles. Furthermore, the uneven weight support onto right and left legs will cause a distortion of viscoelastic ligaments around hip and sacroiliac joints in the long run. Further studies to determine the effect of various manual tasks on the trunk and hip muscles as well as the effect of asymmetrical weight-bearing standing posture on hip and back muscle fatigue may be required.

• Journal of the Korean Society of Physical Medicine
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• 제10권4호
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• pp.107-112
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• 2015

PURPOSE: This study investigated the effects of lower limb and trunk muscles activation on seat angle and height during sit to stand and stand to sit. METHODS: Subjects were instructed to sit and stand on different angles and heights; $0^{\circ}$(43cm), $5^{\circ}$(48cm), $10^{\circ}$(51cm) and $15^{\circ}$(58cm). Measurements were conducted from sit to stand and stand to sit for external oblique, transversus abdominis, rectus femoris, vastus medialis, vastus lateralis, tibialis anterior and gastrocnemius muscle activation by surface EMG. The muscle activation was measured three times for five seconds in each posture, and the %RVC value was calculated after the exclusion of one second before and after this measurement. This calculation standardized the data from each participant so it could be comparatively analyzed. RESULTS: The external oblique, tibialis anterior, and erector spinae muscles showed significant difference in $10^{\circ}$(51cm), $15^{\circ}$(58cm) and $0^{\circ}$(43cm), rectus femoris, in $15^{\circ}$(58cm) and $0^{\circ}$(43cm)(p<.05) during sit to stand. The external oblique, tibialis anterior, and rectus femoris muscles showed significant difference in $0^{\circ}$(43cm) and $15^{\circ}$(58cm), erector spinae and vastus medialis muscles showed significant difference in $10^{\circ}$(51cm), $15^{\circ}$(58cm) and $0^{\circ}$(43cm)(P<.05) during stand to sit. CONCLUSION: The present study findings indicate that the toilet seat angle and height could affect muscle activities of the lower limb and trunk.

• Journal of Digital Convergence
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• 제11권11호
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• pp.545-551
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• 2013

This study aimed to compare the effects of microcurrent stimulation and rest on the fatigue index by applying both to subjects who had accumulated fatigue after performing short-duration physical activity. The experiment was performed at S University from December 2012 to February 2013, on 22 healthy men in their 20s, who were right-handed, and without peripheral or musculoskeletal diseases. All subjects lifted a 10-kg box lift and lower 100 times in 15 minutes. Immediately after that, muscle fatigue index (Median Frequency: MF) and blood fatigue index (Creatine Kinase Lactate: CK, Lactate Dehydrogenase: LDH) were measured by using surface electromyography. The subjects were divided into two groups, and microcurrent stimulation and rest were mediated to the experimental and control groups, respectively, for 20 minutes. After intervention, muscle fatigue index and blood fatigue index were measured and the changes in the accumulated fatigue index were compared. Both groups manifested significantly decreased cumulative fatigue after applying the mediation compared to the pre-intervention level (p < .05), the only exception being the fatigue index of the left erector spinae in the rest group. Compared to the rest group, the microcurrent stimulation group showed a significant decrease in muscle fatigue index (p < .05) but no significant differences were found in the blood fatigue index. Given the results of this study, microcurrent stimulation is considered to be helpful in muscle fatigue recovery for workers who have to perform repetitive movements lifting weights, and additional studies on the correlations of the fatigue recovery with respect to the long-term follow-up of fatigue index and mediation time are necessary.

• The Korean Journal of Emergency Medical Services
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• 제18권3호
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• pp.7-18
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• 2014

Purpose: We aimed to investigate trunk angle and muscle activation of the extremity and back to evaluate the effect of chest compression on work-related musculoskeletal disorders in 119 emergency medical technicians (EMTs). Methods: Eighteen 119 EMTs performed 2-minute chest compression without interruption on a cardiopulmonary resuscitation manikin, during which we measured changes in the trunk and shoulder joint angles, muscle activation (triceps brachii, biceps brachii, erector spinae, gluteus maximus, pectoralis major, rectus abdominis, and rectus femoris) and chest compression accuracy. Results: The decrease in trunk angle by trunk muscle activation was the highest in event 2, the major direction of chest compression. Both shoulder joint angles had no significant difference. Muscle activation of the triceps brachii (p < .01), biceps brachii (p < .05), rectus abdominis (p < .05) and rectus femoris (p < .01) significantly increased during the compression phase compared with the decompression phase, with the rectus femoris showing an increase of 19%. Muscle activation of the erector spinae significantly increased in the decompression phase compared with the compression phase (p < .01). Conclusion: 119 EMTs mainly use the triceps brachii, biceps brachii and pectoralis major muscles during chest compression.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• 제13권3호
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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.

• The Korean Journal of Pain
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• 제34권1호
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• pp.106-113
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• 2021

Background: We aimed to investigate the analgesic efficacy of an erector spinae plane block (ESPB) in immediate breast reconstruction (IBR) with a tissue expander. Methods: Adult women undergoing IBR with a tissue expander after mastectomy were randomly assigned to either intravenous patient-controlled analgesia (IV-PCA) alone (group P) or IV-PCA plus ESPB (group E). The primary outcome was the total amount of opioid consumption during 24 hours postoperatively between the two groups. Secondary outcomes were patient satisfaction, pain score at rest and on shoulder movement using numerical rating scale, incidences of postoperative nausea and vomiting (PONV), and a short form of the brief pain inventory (BPI-SF) at 3 and 6 months after surgery between the groups. Results: Fifty eight patients completed the study. At 24 hours postoperatively, total opioid consumption was significantly less in group E than in group P (285.0 ± 92.0, 95% confidence interval [CI]: 250.1 to 320.0 vs. 223.2 ± 83.4, 95% CI: 191.5 to 254.9, P = 0.005). Intraoperative and cumulative PCA fentanyl consumption at 3, 6, 9, and 24 hours were also less in group E than in group P (P = 0.004, P = 0.048, P = 0.020, P = 0.036, and P < 0.001, respectively). Patient satisfaction was higher in group E (6.9 ± 1.8 vs. 7.8 ± 1.4, P = 0.042). The incidences of PONV was similar. Conclusions: The ESPB decreased postoperative opioid consumption and increased patient satisfaction without significant complications after IBR with a tissue expander after mastectomy.

• Journal of Korean Physical Therapy Science
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• 제29권3호
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• pp.12-20
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• 2022

Background: The purpose of this study was to investigate the changes of trunk and lower extremity muscle activity according to the compensation of arm during bridge movement of healthy subject. Design: Cross-sectional Study. Methods: Twenty healthy subjects participated in this study. The subjects performed bridge exercise with 3 different arm positions(arm abduction 45°, 90° and cross-arms) and measured the muscle activity of the trunk and lower extrimity. During bridge exercise with 3 different arm positions, trunk (rectus abdominis, erector spinae) and lower extrimity muscle activity (gluteus medius, biceps femoris, tibialis anterior) were measured using wireless surface EMG. Results: Rectus abdominis and gluteus medius muscle were most activated during bridge exercise with arm abduction 90° and erector spinae and biceps femoris muscle were most activated during bridge exercise with arm abduction 45°. In addition, tibialis anterior muscle was most activated during bridge exercise with arm cross. However, these difference in muscle activity according to the arm position was not statistically significant. Conclusion: As a result of this study, we think that the change in arm position does not induce sufficient instability to increase the muscle activity of the trunk and lower extremity muscles. Therefore, various approaches for inducing instability of the support surface for increasing muscle activity when applying bridge movement in clinical practice should be explored.

• Journal of the Korean Society of Physical Medicine
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• 제5권3호
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• pp.405-412
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• 2010

Purpose : The purpose of this study was to assess the effects of the trunk muscle activity on bridging exercise according to the knee joint angle. Methods : Twenty-five healthy adults volunteered to participate in this study. Subjects were required to complete following four bridging exercises; knee joint flexion $120^{\circ}$, $90^{\circ}$, $60^{\circ}$, $45^{\circ}$. Surface electromyography from selected trunk muscles was normalized to maximum voluntary isometric contraction. Muscle activity was measured by QEMG-4 system(LXM 3204, Laxtha Korea). A repeated measures of one-way ANOVA with post-hoc Bonferroni's correction was used to determine the influence of bridging exercise on muscle activity for each muscle and descriptive statistics was used to determine local/global muscle ratio. Results : The internal oblique of bridging exercises $120^{\circ}$, $90^{\circ}$ showed significantly(p<.05). The erctor spinae of all bridging exercises showed significant excepted between $60^{\circ}$ and $45^{\circ}$(p<.05). Median of internal oblique/rectus abdominis ratio of $120^{\circ}$ was 4.41, $90^{\circ}$ was 3.94, $60^{\circ}$ was 3.58, $45^{\circ}$ was 3.39. Median of internal oblique/external oblique ratio of $120^{\circ}$ was 2.66, $90^{\circ}$ was 2.43, $60^{\circ}$ was 2.87, $45^{\circ}$ was 2.64. Conclusion : Angular motion decreasing with knee joint flexion made erector spinae activation increase. on the other hand, as decreasing abdomen muscle activation, the more performing motor learning is required for abdomen muscle strength and co-contraction for the trunk stabilization.