• Physical Therapy Rehabilitation Science
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• v.12 no.3
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• pp.327-333
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• 2023

Objective: The purpose of this study was to investigate the effects of wearing an immediate vibration feedback device at the lumbar region on the spine angle in a sitting position. Design: Cross-sectional study. Methods: The subjects were 28 healthy university students who were randomized to three interventions. Each condition (A: in a normal chair with an immediate feedback device, B: on the gym ball, C: in a normal chair) spent 10 minutes watching the video, and the order of the experiments was randomized, and the measurements were taken consecutively. Results: The results showed significant differences in cervical and thoracic angles between conditions and time. Post hoc tests showed no difference at 1 minute, but significant differences at 5 and 10 minutes. Conclusions: In conclusion, all angles increased over time in all conditions, but the condition of wearing an immediate vibration feedback device with a lower increase was more useful in maintaining spinal angles than the other two conditions. This study suggests that immediate vibration feedback devices may be an alternative to prevent the loss of spinal angle in occupations and environments with prolonged sedentary postures, and further research is needed to investigate the effectiveness of prolonged application.

• The Journal of Korean Physical Therapy
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• v.35 no.5
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• pp.151-155
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• 2023

Purpose: This study examined the effect of the degree of neck flexion on the muscle activity of the upper trapezius and sternocleidomastoid muscles in the sitting position. Methods: Twenty-five healthy young adults participated in this study. The study was designed to compare the muscle activity of the upper trapezius and sternocleidomastoid muscles according to the neck flexion angle under the three conditions (neutral position, 15° neck flexion, and 45° neck flexion) in the sitting position. During the neck position of three conditions in sitting, the electromyography (EMG) data (% maximum voluntary isometric contraction) of the muscles were recorded using a wireless surface EMG system. Results: The muscle activity of the upper trapezius muscle and the sternocleidomastoid muscles showed a significant difference according to the three-neck position conditions (p<0.05), and in the post-hoc test results, both muscles showed significant differences between the neutral position and 15° flexion, the neutral position and 45° flexion, and the 15° flexion and 45° flexion, respectively. Conclusion: The load on the muscles around the neck and shoulders increased as the neck flexion angle increased. This suggests that performing various daily activities and tasks with the neck as neutral as possible can prevent muscle fatigue or musculoskeletal disorders.

• Journal of Korean Physical Therapy Science
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• v.24 no.3
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• pp.56-63
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• 2017

Purpose: This study aimed to investigate the effects of sitting posture on cervical flexion angle and pain during smart phone use. Method: This research was performed on 10 adult female students who use smart phones regularly, Each of the two groups of participants used the provided smart phone for 20 minutes while maintaining the given default posture. The evaluation order was randomly selected and the two groups were photographed twice before and after the experiment and were asked to answer if they felt pain during or after the experiment. Result: First, both upright sitting position and vertebra bent position pre and post experiment readings showed significant statistical difference (p<.05). And it is shown to be a factor that induces pain around the neck via increase in neck flexion angle. Second, although there were no significant statistical difference between the pre and post experiment readings of the upright sitting position results and the vertebra bent position results, the vertebra bent position readings showed bigger changes to the neck flexion angle then the upright sitting position readings. Third, all participants from both groups claimed pain in all the tested postures of smart phone usage. Conclusion: Smart phone usage for an extended amount of time in all body postures may prove to have a negative effect making the "optimal" smart phone usage position as a controlled time with neck stretches included in between short sessions.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.1
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• pp.75-81
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• 2017

PURPOSE: The purpose of this study was to compare the activity of the abductor hallucis (AbdH) muscle during short foot exercise (SFE) using foot orthosis (SFE-FO) and the windlass effect (SFO-WE) while sitting and in a one-leg standing position. METHODS: We recruited fourteen subjects with normal feet for this study. Surface electromyography (EMG) was used to measure the muscle activity of the AbdH muscle during SFE, SFE-FO, and SFE-WE while sitting and in a one-leg standing position. Three trials consisting of a 5 s hold for each of the three exercises were performed to measure the EMG activity of the AbdH muscle. Exercise type and position were randomly assigned. Two-way repeated-measures ANOVA was used to analyze the effects of exercise type (SFE vs. SFE-FO vs. SFE-WE) and position (sitting vs. one-leg standing position) on AbdH muscle activity. A statistical significance was set at ${\alpha}=.05$. RESULTS: The EMG activity of AbdH muscle in the SFE-WE exercise was significantly greater than that during SFE and SFE-FO in both exercise positions (p<.001). In addition, the EMG activity of the AbdH muscle in the one-leg standing position was significantly higher than that while sitting (p<.001) during all three exercises. CONCLUSION: These results suggest that SFE-WE is a more effective strengthening exercise than SFE or SFE-FO for activating the AbdH muscle.

• Journal of Korean Physical Therapy Science
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• v.20 no.1
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• pp.43-49
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• 2013

Background and purpose : The shoulder joints permit the greatest mobility of any joint area carries out the important function of stabilization for hand use. Research has now shown that grip strength has proven to be a reliable indicator for quality of life at an older age. The purpose of this study was to investigate the effects of testing posture and shoulder position on grip strength for repetitive gripping task. Methods : Forty(20male, 20female) college adult volunteers with no known shoulder dysfunction participated subject in two testing posture(sitting and standing) and three positions with shoulder flexion: (1) shoulder $0^{\circ}$ flexion (2) shoulder $90^{\circ}$ flexion (3) shoulder $180^{\circ}$ flexion. The paired t-test was used to determine any significant difference in grip strength between the testing posture and shoulder position. Results : The higher grip strength gained in the sitting with the shoulder $180^{\circ}$ flexion and the higher grip strength gained in the standing with the shoulder $180^{\circ}$ flexion. The second experiment showed that the grip strength was significant for sitting, standing position of shoulder $0^{\circ}$ flexion( p<0.05). Grip strength goes up as increase height and weight. Conclusion : These findings demonstrate that the theory does not fit with, because of the influence of gravity, a measure from the shoulder joint is the most high, $0^{\circ}$. And sitting posture and stance in the grip of a difference when compared SIT $0^{\circ}$ and standing position $0^{\circ}$ significant difference in indicated but, $90^{\circ}$ and $180^{\circ}$ in the sitting position and stance in the grip of the difference was not significant difference. To demonstrate the universality of this study's results, future studies should have a larger and more subject as well as a more even distribution of male and female subject. Therefore future research is needed to refine the definition and identify optimal methods of measuring this grip strength.

• Journal of the Ergonomics Society of Korea
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• v.33 no.2
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• pp.155-165
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• 2014

Objective: The aim of this study is to develop an office chair enabling to keep working at reclined sitting posture. Background: Sedentary workers are supposed to change the posture frequently during long hours of sitting. A reclined sitting position has been recommended to reduce disc pressure. But slumped sitting posture caused by the buttock sliding forward without any adjustment of back reclining is commonly observed. The worker seems to have tendency to change the sitting posture maintaining working condition. We assumed the reason to be their hands movement away from the working space when tilting backward. Method: Slide mechanism allowing seat to move forward was designed to maintain the hand position in working space during reclining. A prototype was manufactured and tilting motion was analyzed using motion capture system. Four experiment chairs were tested including the manufactured prototype chair and three other commercial chairs. Results: A backward movements of the hand position were 13.0mm, 101.7mm, 156.1mm and 139.3mm at the prototype chair, compared to chair B, chair C and chair D, respectively. And the movement was remarkably small at the prototype chair. Conclusion: The developed seat sliding chair allows back tilting maintaining hand position at working space. We expect the user tilting back more often than normal tilting chair during seated work. But further investigation is required to figure out the effectiveness of the developed chair using prolonged working hours. Application: The developed office chair directly affects commercialization.

• Journal of International Academy of Physical Therapy Research
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• v.1 no.2
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• pp.113-119
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• 2010

The purpose of this study was to determine the difference of the pinch strength according to testing posture(standing and sitting) and elbow flexion degree($0^{\circ}$, $45^{\circ}$, $90^{\circ}$ and $135^{\circ}$). Forty normal young adults(male: 20, female: 20, mean age: $22.68{\pm}2.91$ years) participated in this study. The methods of this study were categorized as follows: 1) One set of measurement was performed on four elbow flexion degrees($0^{\circ}$, $45^{\circ}$, $90^{\circ}$ and $135^{\circ}$) in two testing postures(standing and sitting) and all subjects were measured for 3 sets testing procedures in every experimental sessions. 2) Pinch strength in various elbow flexion degree was measured after 2 min rest time, and then each test set was repeatedly performed with 5 min rest time to prevent fatigue of muscles involved in the elbow joint. The result was obtained as follow: 1) In standing posture, there was statistically significant difference at $0^{\circ}$ and $45^{\circ}$, $0^{\circ}$ and $90^{\circ}$, $0^{\circ}$ and $135^{\circ}$, $45^{\circ}$ and $90^{\circ}$, $45^{\circ}$ and $135^{\circ}$, $90^{\circ}$ and $135^{\circ}$. 2) In sitting posture, there was statistically significant difference at $0^{\circ}$ and $45^{\circ}$, $0^{\circ}$ and $90^{\circ}$, $0^{\circ}$ and $135^{\circ}$, $45^{\circ}$ and $90^{\circ}$, $45^{\circ}$ and $135^{\circ}$, $90^{\circ}$ and $135^{\circ}$. 3) Statistically, there was no significant difference between standing and sitting posture in same elbow flexion degree, however pinch strength in standing posture was higher than sitting posture.

• The Journal of Korean Physical Therapy
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• v.15 no.4
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• pp.255-298
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• 2003

The purpose of study was to evaluate effects of a trunk muscle strength training on sitting balance of children with spastic cerebral palsy. Five individuals with spastic cerebral palsy(three females. two males; mean aged 6.6) participated three times a week over 6 weeks. Five individuals with spastic cerebral palsy(three females. two males; mean aged 7.0) who did not receive strength training served as control. BPM(Balance Performance Moniter) was used to measured sitting balance and EMG(electromyograph, NORAXON, USA) was used to measured activities of abdominal and erector spine muscle. The obtain result are as follows. 1. The result of this study were following that maximum perturbation area and perturbation velocity were significantly reduced strength training group compared with control group(p<.05). 2. The result of this study were following that maximum perturbation area and perturbation velocity were significantly reduced after strength training compared with pre strength training in strength training group(p<.05). 3. The result of this study were following that maximum perturbation area and perturbation velocity were not significantly reduced at interval of six week in control group(p<.05). 4. The result of this study were following that abdominal muscle activity was significantly increased strength training group compared with control group(p<.05). 5. The result of this study were following that erector spine muscle activity was significantly increased strength training group compared with control group(p<.05). 6. The result of this study were following that abdominal muscle activity and erector spine muscle were significantly increased after strength training compared with pre strength training in strength training group(p<.05). 7. The result of this study were following that abdominal muscle activity and erector spine muscle were not significantly increased at interval of six week in control group(p<.05). In conclusion, the result of this study suggest that improved sitting balance and increased activities of trunk muscle by trunk strength training in spastic cerebral palsy. The result was proposed that therapeutic approach of spastic cerebral palsy with impaired sitting balance should use trunk strength training.

• Journal of The Korean Society of Integrative Medicine
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• v.5 no.2
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• pp.11-17
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• 2017

Purpose : The aim of this study was to verify differences in cervicocephalic joint position sense error after different sustained sitting postures in healthy young adults. Methods : Twenty-five healthy adults(12 men, 13 women) participated in this study. Repositioning errors of neck movement were observed in participants during joint repositioning tasks. During 2 test days with a 1-week interval, the participants performed forward head posture and upright sitting posture in random order. Both head-to-neutral(HTN) and head-to-target(HTT) tasks were performed on each day. On the first day, the participants sat slouched or upright for 10 minutes. Then, they sat upright and moved their heads at a self-selected speed with their eyes-closed to pre-determined neutral and target positions as accurately as possible. The participants noticed that when they reached a pre-determined position, the errors between pre-determined neutral and target positions and current position was recorded. The tasks consisted of flexion, extension and lateral bending. On the second day, the same test was performed after another sitting posture for 10 minutes. Repositioning error values were collected by using a smart phone-based inclinometer. The mean value for three trials was used for data analysis. A paired t-test was used for statistical analysis. Results : Significant differences in joint repositioning errors were found between the repositioning error after different sitting postures on the sagittal plane for both the HTN and HTT tasks (P<.05). No significant differences in errors on the coronal plane were found (P>.05). Conclusion : Cervicocephalic joint position sense can be affected by sitting postures, especially on the sagittal plane.

• Physical Therapy Korea
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• v.16 no.2
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• pp.16-23
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• 2009

The purpose of this study was to investigate the effects postural changes on respiratory muscles and acoustic parameters of the children with spastic cerebral palsy. Nine children with spastic cerebral palsy who required assistance when walking were selected. The ages of the children ranged from 6 to 9 years old. The phonation of the sustained vowel /a/ and the voice qualities of each child such as fundamental frequency($F_0$; Hz), pitch variation (Jitter; %), amplitude variation (Shimmer; %) and noise to harmonic ratio (NHR) were analyzed by Multi-Dimensional Voice Program (MDVP). The muscle activity of three major respiratory muscles: pectoralis major muscle, upper trapezius muscle and rectus abdorminalis muscle, were measured by examining the root mean square (RMS) of the surface EMG to investigate the impact of changes in the adjusted sitting posture of each subject. However, the RMS of pectoralis major muscle showed a significant differences (p<.05). Secondly, there were no significant differences in $F_0$, Jitter and Shimmer between pre and post posture change, but there was a significant difference in NHR (p<.05). The data were collected in each individual; once prior and once after the sitting posture change. The data were analyzed by Wilcoxon signed ranks-test using SPSS version 14.0 for Windows. The findings of this study were as follows; Firstly, the RMS of upper trapezius and rectus abdorminalis muscle were not significant different between pre and post sitting posture changes. From the result, it is concluded that changes in the adjusted sitting posture decreases the abnormal respiratory patterns in the children with spastic cerebral palsy which is characterized by the hyperactivity of the respiratory muscles in breathing. Also, there is increased on the voice qualities in children with spastic cerebral palsy.