• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 추계학술대회 논문집
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• pp.195-196
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• 2008

• Journal of Biosystems Engineering
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• 제36권4호
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• pp.285-289
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• 2011

Muscle fatigue is characterized as a progressive increase in discomfort arising from the active muscle at moderate load levels are maintained. The median frequency is the most commonly used as a parameter to describe muscle fatigue. However, the estimate of the median frequency is difficult to indicate muscle fatigue because of its high standard deviation and instability. This paper investigates the power changes of the appropriate low frequency band as a fatigue parameter in EMG during isotonic exercise. To select the appropriate band, linear regression lines are employed to calculate the slopes and the coefficient of determination. Three females and seven males volunteered to participate in surface EMG recordings placed on the biceps brachii and each recording experiment continued until their exhaustion. The results of experiment shows that the power changes of the selected low frequency band (15~45 Hz) have linear slopes and high determinant coefficients. Therefore, this fatiguing parameter using the power changes of the low frequency band is valid to measure the state of muscular fatigue.

• 한국운동역학회지
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• 제21권3호
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• pp.353-359
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• 2011

The purpose of this study was to investigate the effects of exercise-induced fatigue and blocked vision on postural control during upright stance in elderly women. The study population included 22 women who were aged over 65 years, had no sustained orthopedic damage within the last 6 months, and had been randomly recruited. The results were analyzed with respect to the mediolateral and anteroposterior factors for the center of pressure. The exercise-induced fatigue and the absence of visual information increased the anteroposterior and mediolateral velocity for center of pressure. This means that the elderly women could control their posture through many sways. In conclusion, the exercise-induced fatigue and the blocked vision decreased ability of the postural control in elderly women. Further research on the change of postural control in relation to the types of exercise-induced fatigue and the levels of muscular fatigue is expected.

• 국제물리치료학회지
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• 제9권2호
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• pp.1498-1507
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• 2018

The purpose of this study was to examine the immediate effect of neck stabilization exercise and Swiss ball exercise on the recovery from the fatigue of neck muscles induced. The turtleneck posture was set artificially by using Smartphone with healthy adults. Repetitively measured ANOVA was executed to examine the changes in the muscle fatigue of sternocleidomastoid, upper trapezius, and splenius capitis among three-time intervals (at the time of general resting, work and after intervention) in the three intervention groups (neck stabilization exercise group, Swiss ball exercise group, and ordinary rest group). There were no significant differences in the changes of fatigue of sternocleidomastoid muscle among all three intervention groups at the time of general resting, work and after intervention (p>.05). Although there was no significant difference in the changes in the fatigue of upper trapezius and splenius capitis muscles between the intervention groups at the time of general resting and work (p>.05), there was the significant difference between the three intervention groups at the time of work and after intervention (p>.05). This study suggest that Swiss ball exercise is more effective in reducing the muscular fatigue of the neck and shoulder at a turtleneck posture than neck stabilization exercise.

• 대한인간공학회지
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• 제33권6호
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• pp.565-575
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• 2014

Objective: The aim of this study is to evaluate the effect of weight of load and time on the physical workload of repetitive upper-limb tasks with handling light weight loads using EMG and perceived discomfort, and to investigate the relationship between EMG and perceived discomfort for those repetitive tasks of moving light weight loads. Background: Repetitive upper-limb motion is known as one of the main risk factors of musculoskeletal disorders, and a lot of repetitive tasks are carried out while handling light weight loads in the industry. In evaluating the workload of repetitive tasks handling light weight loads, EMG and perceived discomfort can be used, though their relationship in those work conditions are not much investigated. Method: A laboratory experiment with 18 healthy males were conducted to record EMG signals from 5 muscle sites of the right arm and shoulder and rate perceived discomforts for the body parts and the whole body while carrying out repetitive materials-handling tasks for 52min. The subjects were divided into 3 groups which handled the loads of 1kg, 2kg and 3kg, respectively. ANOVAs were conducted to analyze the effects of the weight and time on RMS of EMG amplitude (normalized RMS: NRMS), median frequency of power spectrum of EMG (normalized MDF: NMDF) and perceived discomfort. The correlations between NRMS and NMDF and perceived discomfort were also analyzed. Results: Statistically significant muscular fatigue effects were not found from NRMS and NMDF in most muscles, while there were significant increases of discomfort as the task time elapsed. It was shown that there were an increasing trend of the muscular activity as the weight of load increased and a decreasing trend of median frequency of EMG of upper and lower arms as time elapsed. It was found that there were significant negative correlations between NMDFs from the lower arm and discomfort ratings, though the relationships were weak. Conclusion: It can be concluded that the working conditions adopted in this study were not enough to induce muscular fatigue, while there was significant increase in perceived discomfort. A further study is necessary to integrate the objective and subjective measures for more reliable and sensitive evaluation of workload of repetitive tasks of handling light weight loads. Application: This study can be used as a basic study for the evaluation of workload of repetitive tasks handling light weight loads.

• 한국전문물리치료학회지
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• 제14권3호
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• pp.9-15
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• 2007

The purpose of this study was to investigate electromyographic activities of the flexor digitorum superficialis (FDS) and the flexor carpi ulnaris (FCU) by the shape of the ultrasound head. Twelve healthy subjects participated and performed ultrasound therapy with a round head and a long handled head during each 5-minute application. Electromyographic activities of the FDS and FCU were recorded by surface electrodes and normalized by maximal voluntary isometric contraction (MVIC) values. There was no difference in the muscular fatigue of FDS and FCU as determined by the shape of the ultrasound head (p>.05). Without the shape of head, the mean power frequency decreased with the time. There also was no difference in %MVIC of the FDS and FCU as determined by the shape of the ultrasound head (p>.05), but the force exerted exceeded 20%MVIC. There was however a significant difference in the amount of cumulative workload of the FDS and FCU as determined by the shape of ultrasound head (p<.05). The workload was however not affected by the shape of the ultrasound head. Constant static grasp of ultrasound transducer head during ultrasound therapy is considered a high risk factor of work-related musculoskeletal disease.

• 재활복지공학회논문지
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• 제6권1호
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• pp.51-58
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• 2012

본 연구에서는 근전도 신호를 기반으로 하여 환자의 재활 운동 시 발생하는 근 피로도의 변화에 따른 능동형 운동 부하 제어 시스템을 개발하였다. 본 능동형 부하 제어 시스템에 적합한 근 파라미터를 선정하기 위해 건강한 남성 12명을 대상으로 사전 실험을 수행하여 근전도 신호를 획득하였다. 또한 선정된 근 파라미터를 이용한 능동형 운동 부하 제어 시스템을 평가하기 위하여 근 골격계 질환이 없는 건강한 남성 10명을 대상으로 실험을 수행하였다. IEMG(Integrated electromyogram) 변화에 따른 운동 부하 변화를 관찰하여 개발된 능동형 부하 제어 시스템의 유용성 및 정확성을 확인하였으며, 개인의 주관적 피로도를 나타내는 운동자각도(rating of perceived exertion)를 활용하여 근 피로도와의 상관관계를 분석하였다. 따라서 본 연구에서 제안한 능동형 운동 부하 제어 시스템은 재활 운동 수행 시 환자 개개인에 적합한 초기 부하 및 운동량 조절에 유용할 것으로 사료된다.

• 국제물리치료학회지
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• 제3권2호
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• pp.422-428
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• 2012

The present study purposed to examine the effects of transcutaneous electrical nerve stimulation, self-stretching and functional massage on the recovery of muscle contraction force for muscle fatigue caused by sustained isotonic contraction. The subjects of this study were 45 healthy students. They were divided into transcutaneous electrical nerve stimulation group(n=15), self-stretching group(n=15) and functional massage group(n=15), and using Primus RS. We observed the pattern of changes in maximal voluntary isometric contraction force(MVIC) after causing muscle fatigue in quadriceps femoris muscle through sustained isotonic contraction. Maximal voluntary isometric contraction force(MVIC) were greatly increased after transcutaneous electrical nerve stimulation, self-stretching and functional massage. In the comparison of recovery rate of muscle contraction force for muscle fatigue caused by sustained isotonic contraction among the treatment groups, it did not show any significant differences. However, it showed that each treatment may be effective in recovery of muscle fatigue caused by sustained isotonic contraction.

• 한국응급구조학회지
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• 제24권3호
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• pp.79-87
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• 2020

Purpose: This study sought to determine how the act of performing cardiopulmonary resuscitation (CPR) affects the rescuer's muscle tone, stiffness, and fatigue in the lumbar region. Methods: The research subjects were 30 healthy men in their twenties in possession of a Basic Life Support (BLS) provider certificate. In this study, the CPR rescuer's muscle tone and stiffness in the upper and lower lumbar regions were measured in the resting position, starting position, and position after 10 min. Their level of fatigue was measured before and after performing CPR. Results: Muscle tone and stiffness in the upper and lower lumbar regions of the research subjects significantly increased throughout the CPR process and lasted up to 10 min after the process (p<.001). The subjects' fatigue also significantly increased post-CPR (p<.001). Conclusion: This study suggests that performing CPR creates muscular and physiological stress, fatigue, and ultimately, lower back pain.

• 한국의류산업학회지
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• 제19권4호
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• pp.504-514
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• 2017

Discomfort as well as muscular pain and musculoskeletal diseases occur in cases of stressed posture due to prolonged pressure. Therefore, the American Academy of Orthopaedic Surgeons (AAOS) and Pediatric Orthopaedic Society of North America (POSNA) recommend that bags that weigh no more than 15 - 20% of the wearer's weight. However, despite the prolonged pressure from using baby carriers, there are no recommendations and limited studies on how to protect wearers. Therefore, this study investigates subjective fatigue according to the usage of waist support and hip seat. Based on this, muscle fatigue and secondary subjective fatigue according to three types of currently commercial baby carriers (X-type, H-type, and H-hip type) were measured. Subjective comfortability was evaluated on a 5 point Likert-scale and subjective fatigue was evaluated on Borg's CR-10 scale. Objective muscle fatigue was also compared by measuring and analyzing electromyogram (EMG). The results of primary subjective fatigue showed statistically significant changes in the shoulders, waist, calves, and soles of the feet according to the usage of hip seats and waist support. Electromyogram measurements also showed less muscle fatigue at the upper trapezius muscle and thoracic erector spine muscle for the H-hip seat baby carrier, which has both waist support and hip seat, compared to an X-type baby carrier, which has neither. However, results of subjective fatigue showed opposite results at the waist despite having same results at the shoulders and beneath the shoulders. This show discrepancies between objective muscle fatigue and subjective fatigue; therefore, that both aspects must be taken into consideration when developing ergonomic baby carriers.