• 한국전문물리치료학회지
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• 제14권3호
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• pp.16-22
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• 2007

The purpose of this study was to determine the influence of muscle fatigue in elbow flexors on the sense of force reproduction. Fifteen healthy subjects were recruited for this study. Maximum voluntary force (MVF) of elbow flexor muscles was measured by a digital tensiometer. Force errors were measured to test accuracy of the sense of force reproduction in elbow flexors. The subject was required to flex the elbow joint, to maintain and concentrate on about 20% of the MVF target force under visual feedback for 3 seconds. After a 5 second period rest, the subject was asked to duplicate the target force actively. Muscle fatigue was evoked with isometric contraction of the elbow flexors. Isometric contraction was continued until a 50% drop in MVF. The difference, in kilogram between the target force and the reproduced force was calculated for measuring force error. Force errors were compared between the non-fatigued condition and the fatigued condition by the paired t-test. Force errors were significantly increased in the fatigued condition compare to non-fatigued condition. This result suggests that the sense of force reproduction can be disturbed by localized muscle fatigue.

• 한국정밀공학회지
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• 제22권6호
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• pp.207-212
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• 2005

The purpose of this work is to develop the FES controller that can cope with the muscle fatigue which is one of the most important problems of current FES (Functional Electrical Stimulation). The feasibility of the proposed FES controller was evaluated by simulation. We used a fitness function to describe the effect of muscle fatigue and recovery process. The FES control system was developed based on the biological neuronal system. Specifically, we used PD (Proportional and Derivative) and GC (Gravity Compensation) control, which was described by the neuronal feedback structure. It was possible to control of multiple joints and muscles by using the phase-based PD and GC control method and the static optimization. As a result, the proposed FES control system could maintain the cycling motion in spite of the muscle fatigue. It is expected that the proposed FES controller will play an important role in the rehabilitation of SCI patient.

• 국제물리치료학회지
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• 제11권4호
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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.

• 재활간호학회지
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• 제4권1호
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• pp.84-93
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• 2001

The effects of brisk walking & muscle strengthening exercise on pain, fatigue, physical function & disease activity were examined in 28 patients with rheumatoid arthritis. Research design was a quasi-experimental study of non-equivalent control group pretest-posttest design. 14 for the experimental group and 14 for the control group were selected from the out patients on rheumatoid arthritis clinic of Dong-A University Hospital. The experimental group underwent 16 weeks of brisk walking and muscle strengthening exercise using Thera-Band. Pain, fatigue, physical function & disease activity was measured before and after 16 weeks of exercise. At baseline test, Fatigue & physical function score between groups were significantly different. So differences with in experimental group(baseline versus follow up) were compared with differences within the control group by Mann-Whitney test. There were significant differences between groups in the difference score on pain (U=6.50 p<.001) and fatigue (U=26.5 p<.01). For the experimental group, the score on the pain & fatigue was significantly decreased but no changed for the control group. Also there was a significant differences between groups in the difference score of the physical function (U=22.5 p<.001). For the experimental group, the score of the physical function has been significantly in creased. However, for the control group, it has been no changed. But there were no significant differences between groups in the ESR (erythrocyte sedimentation rate) and the CRP (C-reactive protein)level. In summary, brisk walking & muscle strengthening exercise led to significant improvements in pain, fatigue, and physical function without exacerbating disease activity in patients with rheumatoid arthritis.

• 대한의용생체공학회:의공학회지
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• 제16권3호
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• pp.317-324
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• 1995

A need exists for the accurate identification of time series models having time varying parameters, as is important in the case of real time identification of nonstationary EMG signal. Thls paper describes real time identification and muscle fatigue monitoring method of nonstationary EMG signal. The method is composed of the efficient identifier which estimates the autoregressive parameters of nonstationary EMG signal model, and its real time implementation by using T805 parallel processing computer. The method is verified through experiment with real EMG signals which are obtained from surface electrode. As a result, the proposed method provides a new approach for real time Implementation of muscle fatigue monitoring and the execution time is 0.894ms/sample for 1024Hz EMG signal.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2009년도 추계학술발표논문집
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• pp.1010-1013
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• 2009

본 논문에서는 STFT을 이용한 이두박근의 근전도 신호 근피로도 측정 방법을 제시한다. 개선된 STFT방식은 기존연구에서 사용되어져 왔던 중간주파수를 이용한 근피로도 측정 방법과 달리 STFT를 이용한 시간, 주파수 평면에서 2차원 영상을 이용하여 근피로도를 측정할 수 있는 방법이다. 제안한 방법은 이두박근에서 수집한 근전도 신호의 근피로도 측정에 사용하여 제안한 방법의 타당성을 검증하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.158-161
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• 1989

This paper describes the AR model of EMG signal during maximum voluntary contraction. By comparing the AR coefficients and the reflection coefficients of the AR model with the median frequency of power spectrum, it if proved that muscle fatigue can be measured by the AR and the reflection coefficients. In the estimation procedure of AR model parameter, the auto-correlation method is superior to the covariance method, and it is determined that the optimal order is six. As the muscle becomes fatigue, the median frequency of power spectrum is declined, and the AR coefficient [$a_1$ ] and the reflection coefficient [$k_1$ ] are also decreased. Therefore the muscle fatigue can be measured by the AR parameter.

• 대한의용생체공학회:의공학회지
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• 제10권1호
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• pp.11-16
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• 1989

This paper describes the AR model of EMG signal during maximum voluntary contraction. By comparing the AR coefficients and the reflection coefficients of the AR model with the median frequency of power spectrum, it is proved that muscle fatigue can be measured by the AR and the reflection coefficients. In the estimation procedure of AR model parameter, the autocorrelation method is superior to the covariance method, and it is determined that the optimal order is six. As the muscle becomes fatigue, the median frequency of power spectrum is declined, and the AR coefficient [$a_1$] and the reflection coefficient [$k_1$] are also decreased. Therefore the muscle fatigue can be measured by the AR parameter.

• 산업경영시스템학회지
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• 제35권2호
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• pp.30-36
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• 2012

This study is aimed to show that an asymmetric load in the frontal plane leads to an increase in low back loading and fatigue in comparison with a symmetric load when workers lift an external weight by investigating previous studies and verifying the phenomenon with an experiment. Ten male subjects are required to lift and hold an given external load at 70cm height during 50sec, then the EMG amplitude and median frequency on bilateral low back muscle groups (Longissimus, Iliocostalis, and Multifidus) are recorded and analyzed. Independent variables are two-level load weight (13kg, 20kg) and three-level LCG (Center, 6.5cm to the right, and 13cm to the right), and dependent variables are EMG amplitude average, difference, and Fatigue Index (FI). Results show that load weight increases significantly amplitude average and FI, but LCG does significantly amplitude difference and FI significantly (P-value < 0.05). Also the correlation coefficient between amplitude difference and FI is over 0.99. These implies that trunk loading should be explained by not EMG amplitude but muscle fatigue aspect since the association between an external load and amplitude is linear, but the relationship between an external load and median frequency as muscle fatigue index is almost exponential.

• 디지털융복합연구
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• 제11권11호
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• pp.545-551
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• 2013

본 연구는 단시간 들기 내리기 작업을 실시한 누적피로 대상자에게 미세전류자극 및 휴식을 적용하여 피로 지수에 미치는 영향을 비교하였다. 2012년 12월부터 2013년 2월까지 S대학에서 연구가 진행되었으며, 말초질환 및 근골격계 질환이 없고 오른손을 사용하는 20대의 신체 건강한 남자 22명을 대상자로 선정하였다. 모든 대상자는 10 kg 상자를 15분 동안 들기 내리기를 100회 실시한 직후, 표면근전도기를 이용한 근피로지수(Median Frequency : MF)와 혈액피로지수(Creatine Kinase Lactate : CK, Lactate Dehydrogenase : LDH)를 측정하였다. 두 그룹으로 나누어 실험군에는 미세전류자극을 대조군에는 휴식을 각각 20분간 중재하였다. 중재 후, 근피로지수와 혈액피로지수를 측정하여 누적 피로지수의 변화를 비교하였다. 그 결과 휴식그룹의 왼쪽 척주세움근 피로지수를 제외한 두 그룹 모두에서 중재방법 적용 전보다 적용 후 유의한 누적피로의 감소(p<.05)가 있었고, 미세전류의 자극은 휴식과 비교했을 때, 근피로지수의 유의한 감소(p<.05)를 보였지만, 혈액피로지수는 차이가 없었다. 본 연구의 결과를 토대로 미세전류자극은 반복적인 들기와 내리기 작업 종사자들의 근피로회복에 도움이 될 것이라 사료되며, 장시간 피로지수 추적조사 및 중재 적용시간에 따른 피로회복의 상관관계 대한 추가적인 연구가 필요하다.