• PNF and Movement
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• v.21 no.3
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• pp.299-307
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• 2023

Purpose: The purpose of this study was to compare the effects of new exercises (combined cervical and thoracic extension exercises) with those of conventional cervical extensor strengthening exercises (sitting cervical extension exercises) and thoracic extensor strengthening exercises (prone thoracic extension exercises). Method: Fifteen healthy subjects performed sitting cervical extension exercises, prone thoracic extension exercises, and combined cervical and thoracic extension exercises. During each exercise, electromyography was used to measure muscle activity in the erector spinae with C4 and T4 levels. The measured data were analyzed using one-way repeated analysis of variance. Results: With different exercises, there were significant differences in activity in the erector spinae muscle (p < 0.05). The activity in the erector spinae muscle increased significantly during the combined cervical and thoracic extension exercises compared to the sitting cervical extension (p < 0.05) and prone thoracic extension exercises (p < 0.05). The sitting cervical extension exercises significantly increased activity in the cervical erector spinae muscle compared to the prone thoracic extension exercises (p < 0.05). Activity in the thoracic erector spinae muscles was significantly increased during the prone thoracic extension exercises compared to during the sitting cervical extension exercises (p < 0.05). Conclusion: These findings suggest that the newer exercises effectively increase activity in the cervical and thoracic extensor muscles.

• Journal of the Korean Society of Physical Medicine
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• v.8 no.3
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• pp.417-424
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• 2013

PURPOSE: We investigated the relationship between the segment of erector spinae during a core stability exercise according to visual control. METHODS: The subjects of this study were 20 healthy students. An 8-channel electromyograph was used to measure muscle activities of the erector spinae by segment(cervical, thoracic and lumbar) during a core stability exercise according to visual control. The collected data were analyzed using the independent t-test and Pearson-test. RESULTS: The activity of the erector spinae for all segment was higher without the vision than with. The activity of right cervical erector spinae was significantly increased by increasing the activity of the left thoracic erector spinae during a core stability exercise with vision (r= .555). The activity of left thoracic erector spinae was significantly increased by increasing the activity of the left lumbar erector spinae during a core stability exercise without vision (r= .472). CONCLUSION: There was a positive correlation between the cervical and thoracic segment of erector spinae during a core stability exercise with vision. There was a positive correlation between the thoracic and lumbar segment of erector spinae during a core stability exercise without vision.

• Physical Therapy Korea
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• v.20 no.3
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• pp.19-26
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• 2013

The smart-phone has become a necessity for most people. In this study, we determined that using a smart-phone for 20 minutes can cause increased neck and shoulder muscle activities and fatigue. Seventeen healthy male smart-phone users who attended Yonsei University played a smart-phone game for 20 minutes and changes in their bilateral cervical erector spinae and upper trapezius muscle activities and fatigue were measured. To assess muscle activities and fatigue, we used the following variables: the median frequency, the 50th percentile Amplitude probability distribution function (APDF) value (median load), and the discrepancy in the 90th percentile APDF value and the 10th percentile APDF value (APDF range). A paired t-test was used to compare pre-smart-phone-use status with post-smart-phone-use-status. The median frequency of the bilateral cervical erector spinae and the upper trapezius decreased significantly after 20 minutes of smart-phone use (p<.05). In addition, the 50th percentile APDF value of the bilateral cervical erector spinae and the right upper trapezius increased significantly (p<.05). The APDF range of the bilateral cervical erector spinae and the upper trapezius also increased significantly (p<.05). However, the 50th percentile APDF range of the left upper trapezius was not significantly different (p>.05). These findings suggest that using smart-phones for 20 minutes can induce muscle fatigue and increased neck and shoulder muscle activities.

• Journal of the Ergonomics Society of Korea
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• v.31 no.6
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• pp.741-747
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• 2012

Objective: The purpose of this study is to compare the EMG activities of the trunk muscles when carrying a backpack with belts and without belts. Background: This research aimed to explore the influence of carrying a backpack with belts on the trunk muscles activity and to suggest a desirable method of wearing backpacks. Method: Seventy five adolescents participated in this study. The EMG activities of upper trapezious, cervical erector spinae and rectus abdominis were collected. One way ANOVA was used to analyze the collected data. LSD was used for post-hoc test. Results: The EMG data from treadmill walking showed significant differences between carrying a backpack with belts and without belts for the cervical erector spinae and upper trapezious(p<.05) in all group(A Group: no belt, B Group: lumbar belt, C Group: lumbar-chest belt). In descending walking, significant difference were found for the cervical erector spinae and rectus abdominis in all group. In ascending walking, there were no significant differences in all group. LSD showed that the muscle activity of the trunk muscles decreased significantly when the lumbar belt and lumbar-chest belt were worn. Conclusion: The trunk muscles activities were decreased when the subjects were wearing a backpack with belts, comparing with wearing a backpack without belts. Application: These results can be used to provide useful information on how wearing a backpack in adolescent.

• The Journal of Korean Physical Therapy
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• v.32 no.6
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• pp.378-382
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• 2020

Purpose: This study aimed to examine the effects of forward head posture on the flexion-relaxation ratio (FRR) and muscle activity during sustained neck flexion and to investigate the correlation between craniovertebral angle and FRR. Methods: Nineteen subjects participated in this study and were allocated to a forward head posture (FHP) group or a non-forward head posture (NFHP) group. Craniovertebral angle (CVA) and FRR were measured in all subjects, and all participants performed a standardized cervical flexion-extension movement in two phases: Phase I, sustained cervical full flexion for 5s; and Phase II, cervical extension with the return to the starting position for 5s. The value of CVA has calculated three times, and the value of FRR was measured three times in order to obtain the mean value. Results: FRR values in the FHP and NFHP group were significantly different (p<0.05). Phase I was significantly different, but the Phase II was not significantly different between the FHP and NFHP group (p>0.05). There was a significant correlation between the muscle activity of Phase I and CVA (p<0.05). However, FRR and the muscle activity of the Phase II were not a significant correlation with the CVA (p>0.05). Conclusion: FHP increases the muscle activity of the cervical erector spinae during sustained neck flexion and reduces FRR, which can cause fatigue in the cervical erector spinae. In addition, for those with a smaller CVA, muscle activity of the cervical erector spinae is increased during sustained neck flexion, which can increase neck muscle tension.

• Journal of Convergence for Information Technology
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• v.7 no.5
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• pp.47-51
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• 2017

The purpose of this study was to investigate the effect of wearable sensor wear on the muscle contraction of cervical erector spinae and upper trapezius causing the forward head posture induction in order to reduce the stress induced by the use of smartphone. This study was to investigate the muscle activity of healthy adults in the 20th to 30th generations by dividing them into the control group using the smartphone, the non-wearing group conscious the posture of the head posture, and the wearing group wearing the wearable sensor. There were no differences in muscle activity between cervical erector spinae and upper trapezius compared to the control, non - wearing, and wearing groups. In addition, the changes in muscle activity of cervical erector spinae muscles were increased in all groups, but the muscle activity of upper trapezius muscles were in the wear group compared to the non-wear group and the control group, but there was no statistical significance. That is, wear of the wearable sensor may be effective in controlling the conscious posture, but it may cause the compensation of another part.

• Journal of Convergence for Information Technology
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• v.7 no.4
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• pp.97-103
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• 2017

The purpose of this study was to investigate muscle activity of cervical erector spinae & upper trapezius while using a smartphone according to anterior pelvic tilt & posterior pelvic tilt in sitting position. & we also want to obtain basic data necessary for development of IoT devices. Fifteen healthy men & women aged 20-30 were enolled, After anterior pelvic tilt & posterior pelvic tilt in sitting position were adjusted, they used a smartphone for 5 minutes & EMG signal was measured simultaneously. We used median 3 minutes of measured EMG signal. The results of this study were as follows: In the sitting position, the use of smartphone in anterior pelvic tilt had significantly lower %RVC values in both cervical erector spinae (p <.001), left upper trapezius (p <.001) & right upper trapezius (p <.002) in comparison with posterior pelvic tilt. This means that anterior pelvic tilt make vertebrae maintain normal curvature & prevent forward head posture occurred while using a smartphone. It reduces loads around neck & shoulders, so that %RVC value is significantly lowered. In the future, new posture corrected IoT devices with an aspect of pelvic tilt should be developed.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.2
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• pp.71-77
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• 2019

Purpose: The purpose of this study was to compare the level of muscle activation on the cervical erector spinae (CES), lumbar erector spinae (LES), and upper trapezius (UT) according to the sitting postures while using a smartphone in the bathroom. Method: Thirty-two healthy subjects were recruited for this study. The CES, LES, and UT were evaluated by surface electromyography according to two sitting postures while using a smartphone on the toilet seat. A paired t test was performed for the root mean square of reference voluntary contraction (%RVC) comparisons between two sitting postures, and one-way ANOVA was used to compare the three muscle activations within each posture. Results: A comparison between the two sitting postures revealed the muscle activation of both CESs in sitting posture 2 and both LESs in sitting posture 1 to be significantly higher than those of the others. In sitting posture 1, the muscle activation of both LESs was significantly higher than those of the CES and UT. In sitting posture 2, the muscle activation of both CESs was significantly higher than those of the LES and UT. Conclusion: High muscle activation of the CES and LES was observed according to the sitting postures when using smartphone in the restroom. Therefore, long time use of smartphones on a toilet seat should be avoided.

• Physical Therapy Korea
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• v.27 no.4
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• pp.264-271
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• 2020

Background: Because a forward-leaning posture can cause increased back muscle activity and pain. Therefore, an innovative method to reduce back muscle activity and pain is required. Objects: This study aimed to investigate the effects of a head support on muscle activity and pain in a forward-leaning posture. Methods: A total of 14 male and 16 female students (average age, 21.65 ± 2.37 years; height, 166.15 ± 7.90 cm; and weight, 60.65 ± 9.00 kg) were recruited for the experiment. Two of them were excluded due to musculoskeletal disorders. The muscle activity and pain in the forward-leaning posture were assessed while participants washed dishes for 7 minutes with and without a head support. The condition of using a head support was randomly performed with a 5-minutes break. To confirm a lumbar flexion angle of 30° during the experiment, myoVIDEO was used, and surface electromyography was used to measure muscle activity. Pain was assessed using a 10-point visual analog scale (VAS). The Wilcoxon signed-rank test was used to analyze the data, with p < 0.05 indicating statistical significance. Results: The cervical, thoracic, and lumbar erector spinae muscle activities significantly decreased with the use of the head support, but there was no significant change in the gluteus maximus. There was a significant decrease in the VAS score for the lumbar erector spinae (p < 0.05), but there was no significant change in the VAS score for the cervical region. Conclusion: The use of a head support in a forward-leaning posture reduced cervical, thoracic, and lumbar erector muscle activity and pain. Therefore, it could be recommended during working in a forward-leaning posture, such as during dishwashing, cooking, and working as a factory employee.

• Journal of International Academy of Physical Therapy Research
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• v.11 no.4
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• pp.2203-2211
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• 2020

Background: Backpacks are one of the most widely used accessories in modern society. However, previous studies have shown that carrying a backpack can cause various musculoskeletal problems. Objectives: To investigate the effects of a body-adhesive backpack on craniovertebral angle, sagittal shoulder angle and the muscle fatigue in the upper extremity. Design: Randomized cross-over design. Methods: For this study, 36 healthy university students participated in this study. The experiment was conducted three times using common backpack, and body-adhesive backpack condition. The angles of the cervical spine and shoulder joints of the subjects were calculated without the backpack. Electrodes were placed at upper trapezius, lower trapezius, rectus abdominis and erector spinae to check for muscle fatigue. Subjects carried a backpack and walked on a treadmill for 15 minutes at 4 km/h. The muscle fatigue signal was also measured while walking. After walking, the craniovertebral and sagittal shoulder angles were measured again while subjects carried backpack. Results: As a result of this study, body-adhesive backpack condition showed significant decrease and significant increase in craniovertebral angle and sagittal shoulder angle than common backpack (P<.05). Body-adhesive backpack condition showed significant decrease in upper trapezius, lower trapezius, erector spinae, and rectus abdominis when compared to a common backpack (P<.05). Conclusion: This study suggests that a body-adhesive backpack is more beneficial in correcting body posture than a common backpack.