• 한국응용과학기술학회지
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• 제36권3호
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• pp.1028-1040
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• 2019

본 연구는 내리막 달리기(downhill running, DR) 후 초음파 영상분석을 이용해 대퇴사두근 무리(quadriceps group, QG) 내 근손상의 국소화 여부를 검증하고, DR 동안 운동 강도가 운동유발성 근손상(exercise-induced muscle damage, EIMD) 및 근육 반향세기 변화에 미치는 영향을 규명하려는 목적으로 수행되었다. 규칙적인 신체활동이 없는 건강한 남성 11명이 무작위 교차설계에 따라 서로 다른 강도[low-intensity DR session($50%HR_{max}$), LDR; high-intensity DR session($70%HR_{max}$), HDR]의 DR 운동을 수행하였다. DR 후 EIMD의 심각성은 혈청크레아틴 키나아제(creatine kinase, CK) 활성 수준 변화와 함께 신경근 기능 지수로서 무릎 신전근의 최대 수의적 등척성 수축(maximal voluntary isometric contraction, MVIC) 및 관절가동범위(range of motion, ROM) 변화를 통해 결정되었다. 회색조 분석을 적용한 근육 반향세기 평가는 DR에 따른 QG 내 국소 근육별(rectus femoris, RF; vastus lateralis, VL; vastus medialis, VM; vastus intermedius, VI) 손상 양상을 탐지하기 위해 활용되었다. 모든 세션에서 혈청 CK 활성 수준과 VL 및 VM의 근통증 정도는 운동 후 24시간째(RF의 경우 각각 LDR 24시간째와 HDR 48시간째) 최대에 이르렀으며, 혈청 CK 수준에서 운동 강도에 따른 유의한 차이(p<.05)가 나타난 반면 근통증에서 세션 간 통계적 차이는 없었다. 무릎 관절을 이용한 MVIC 및 ROM과 같은 신경근 기능 지표 및 VM을 제외한 모든 QG 근육 반향세기는 운동 직후 극적으로 감소 또는 증가 후 72시간까지 점진적 회복 양상을 나타내었다. 그러나 신경근 기능 지표에서 운동 강도에 따른 통계적 차이는 없었으나 RF 및 VL 반향세기에서 세션 내 및 세션 간 유의한 차이(p<.01)를 나타내었다. 본 연구의 결과로 ECC를 함유한 DR 운동 시 운동 강도는 DOMS 및 신경근 기능 지표에 부분적으로 영향을 미칠 가능성이 있으며, 특히 혈청 CK 수준과 함께 RF 및 VL의 근육 반향세기는 운동 강도의 영향을 직접적으로 반영한다는 사실을 알 수 있다. 또한, 현재 연구결과는 DR 동안 ECC를 겪는 QG 내 국소 근육 간 근손상 정도가 다를 수 있으며 초음파 근육 반향세기가 국소 근육의 EIMD 심각성을 차별화할 수 있는 유용한 평가기법임을 뒷받침하고 있다.

• 대한영상의학회지
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• 제82권6호
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• pp.1556-1564
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• 2021

목적 정상 대퇴 근육의 탄성도를 정량적으로 측정함에 있어 자기 공명 탄성 검사의 실현 가능성을 확인하고 정상 대퇴 근육의 탄성도를 측정한다. 대상과 방법 이 전향적 연구는 일상적인 보행에 지장이 없는 자원자를 대상으로 대퇴부의 T2 강조 축상 영상과 대퇴 근육의 자기 공명 탄성 검사를 시행하였고 최종적으로 10명의 피실험자가 포함되었다[평균 연령, 32.5세, (범위, 23~45세)]. 탄성 특성은 휴식 상태에서 각 대퇴 근육에서의 전단 탄성 계수를 정량적으로 다음 4개의 대퇴 근육에 대해 측정하였다; 내측넓은근, 외측넓은근, 대내전근, 대퇴이두근. 결과 대퇴 근육의 평균 전단 탄성 계수는 각각 두 명의 판독자에서 내측넓은근은 0.98 ± 0.32 kPa, 1.00 ± 0.33 kPa, 외측넓은근은 1.10 ± 0.46 kPa, 1.07 ± 0.43 kPa, 대내전근은 0.91 ± 0.41 kPa, 0.93 ± 0.47 kPa, 대퇴이두근은 0.99 ± 0.37 kPa, 0.94 ± 0.32 kPa으로 측정되었다. 성별에 따른 전단 탄성 계수의 차이는 유의미하지 않게 나타났다(p < 0.05). 내측넓은근(판독자 1; p = 0.194; 판독자 2; p = 0.355)을 제외한 나머지 대퇴 근육에서 연령은 각 근육의 전단 탄성 계수와 유의미하게 일관된 음의 상관관계를 보였다. 결론 자기 공명 탄성 검사는 개별적인 근육의 탄성 특성을 정량적으로 측정할 수 있는 유용한 검사이다. 내측넓은근을 제외한 대퇴 근육에서 나이는 근육의 전단 탄성계수와 통계학적으로 유의미한 일관된 음의 상관관계를 보였다.

• 대한의용생체공학회:의공학회지
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• 제10권2호
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• pp.109-111
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• 1989

An electrical stimulator was designed to induce locomotion for paraplegic patients caused by central nervous system injury. Optimal stimulus parameters, which can minimize muscle fatigue and can achieve effective muscle contraction were determined in slow and fast muscles in Sprague-Dawley rats. Stimulus patterns of our stimulator were designed to simulate electromyographic activity monitored during locomotion of normal subjects. Muscle types of the lower extremity were classified according to their mechanical property of contraction, which are slow muscle (msoleus m.) and fast muscle (medial gastrocneminus m., rectus femoris m., vastus lateralis m.). Optimal parameters of electrical stimulation for slow muscles were 20 Hz, 0.2 ms square pulse. For fast muscle, 40 Hz, 0.3 ms square pulse was optimal to produce repeated contraction. Higher stimulus intensity was required when synergistic muscles were stimulated simultaneously than when they were stimulated individually. Electrical stimulation for each muscle was designed to generate bipedal locomotion, so that individual muscles alternate contraction and relaxation to simulate stance and swing phases. Portable electrical stimulator with 16 channels built in microprocessor was constructed and applied to paraplegic patients due to lumbar cord injury. The electrical stimulator restored partially gait function in paraplegic patients.

• 한국운동역학회지
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• 제16권2호
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• pp.55-63
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• 2006

The purpose of this study was to investigate the effects of vibration exercise using surface electromyography. Seven male collegiate wrestlers were participated in this study. Each subject stood on the platform and the vibration was induced for 1min. WEMG8 EMG system was used to record muscle activity from Vastus lateralis, Biceps Femoris, Tibialis Anterior, and Gastrocnemius. The EMG data were sampled for 30 sec. during non-vibration and vibration half squat position, respectively. The raw data were band pass filtered to remove noise and full wave rectified Paired sample t-test were performed to see the differences of maximum and average EMG between non-vibration and vibration trials. The results indicated that vibration produced much more muscle contraction than that of non-vibration trial for all selected muscles even though the significant difference was found only from Biceps Femoris. This phenomenon was due to the individual differences so care must be taken to evaluate vibration intensity and position before personal training.

• 대한의용생체공학회:의공학회지
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• 제31권3호
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• pp.217-226
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• 2010

The lower limb orthosis with a pneumatic rubber actuator, which is intended for the assistance and the enhancement of muscular activities of lower limbs was developed in this study. Compared to other knee extension assistive devices being developed by other researchers, our device is designed especially for the elderly people and intended only for slight assistance so that the subjects can keep their muscular strength. For the effectiveness of system, muscular activities of major muscles in lower limbs during sit-to-stand (STS) and squat motion were measured and analyzed. Subjects were performed the STS and squat motion with and without lower limb orthosis. We made comparison muscular activities between with and without lower limb orthosis. Lower limb orthosis was controlled using muscular stiffness force feedback that is controlled by muscular activities of the measured muscle from force sensor. For analysis of muscular activities, electromyography of the subjects was measured during STS and squat motion, and these were measured using MP 150(BIOPAC Systems, Inc.). Muscles of interest were rectus femoris(RF), vastus lateralis(VL), vastus medialis(VM) and vastus intermedius(VI) muscles in lower limbs of the right side. A biodex dynamometer was used to measure the maximal concentric isokinetic strength of the knee extensors of wearing and not wearing orthosis on right side. The test were performed using the concentric isokinetic mode of test with the velocity set at 60°/s for muscles around the knee joints. The experimental result showed that muscular activities in lower limbs wearing orthosis using muscular stiffness force of a vastus medialis muscle was reduced and knee extension torque of an knee joint wearing lower limb orthosis was increased. With this, we confirmed the effectiveness of the developed lower limb orthosis.

• 한국운동역학회지
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• 제26권2호
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• pp.237-242
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• 2016

Objective: The purpose of this study was to compare the joint movements and muscle activities of novices according to pedal type (flat, clip, and cleat pedal). Method: Nine novice male subjects (age: $24.4{\pm}1.9years$, height: $1.77{\pm}0.05m$, weight: $72.4{\pm}7.6kg$, shoe size: $267.20{\pm}7.50mm$) participated in 3-minute, 60-rpm cycle pedaling tests with the same load and cadence. Each of the subject's saddle height was determined by the $155^{\circ}$ knee flexion angle when the pedal crank was at the 6 o'clock position ($25^{\circ}$ knee angle method). The muscle activities of the vastus lateralis, tibialis anterior, biceps femoris, and gastrocnemius medialis were compared by using electromyography during 4 pedaling phases (phase 1: $330{\sim}30^{\circ}$, phase 2: $30{\sim}150^{\circ}$, phase 3: $150{\sim}210^{\circ}$, and phase 4: $210{\sim}330^{\circ}$). Results: The knee joint movement (range of motion) and maximum dorsiflexion angle of the ankle joint with the flat pedal were larger than those of the clip and cleat pedals. The maximum plantarflexion timing with the flat and clip pedals was faster than that of the flat pedal. Electromyography revealed that the vastus lateralis muscle activity with the flat pedal was greater than that with the clip and cleat pedals. Conclusion: With the clip and cleat pedals, the joint movements were limited but the muscle activities were more effective than that with the flat pedal. The novice cannot benefit from the clip and cleat pedals regardless of their pull-up pedaling advantage. Therefore, the novice should perform the skilled pulling-up pedaling exercise in order to benefit from the clip and cleat pedals in terms of pedaling performance.

• 한국산학기술학회논문지
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• 제17권12호
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• pp.363-370
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• 2016

본 연구의 목적은 속도가 다른 트레드밀 훈련이 다리 근두께에 어떠한 영향을 미치는지 알아보고자 하였다. 대상자는 대학생 남녀 36명을 평보군 (n=12)과 속보군 (n=12), 교차보행군 (n=12)으로 나누어 평보군은 평균 속도의 100%의 속도로 훈련을 실시하였고, 속보군은 평균 속도의 130%의 속도로 실시하였으며, 교차보행군은 130%의 속도와 100%의 속도를 각각 교차하면서 보행 훈련을 실시하였다. 훈련은 6주 동안 시행하였고, 주당 3회, 회당 60분간 시행하였다. 측정은 넙다리곧은근과 가쪽넓은근, 장딴지근, 앞정강근의 두께를 비교하기 위해 초음파영상장치를 이용하였다. 연구 결과 넙다리곧은근, 가쪽넓은근, 장딴지근에서 시간에 따라 유의한 증가가 있는 것으로 나타났고, 상호작용 또한 있는 것으로 나타났다. 그리고 앞정강근에서는 시간에 따라 유의한 증가가 있는 것으로 나타났다. 이상과 같은 결과로 보아 평속보다는 속도를 달리한 훈련을 실시하였을 때 다리 근육의 두께 변화에 영향을 미치는 것으로 생각되며, 추후 연구에서는 신경계나 근골격계 질환으로 인한 보행 장애를 가진 환자를 대상으로 재활 프로그램에 적용하는 연구가 지속적으로 이루어져야 할 것으로 생각된다.

• Journal of Nutrition and Health
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• 제40권3호
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• pp.221-228
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• 2007

We determined the effects of dietary manipulations on messenger RNA of peroxisome proliferators activated receptor isoforms (i.e., PPAR ${\alpha},\;{\beta}/{\delta},\;{\gamma}$) in red vastus lateralis muscle of rats. Total 16 male Sprague-Dawley rats were used, and animals were divided into one of two dietary conditions: either chow diet group (CHOW; n=8) in which animals were 134 with standard rodent chow (61.8% carbohydrate, 15.7% fat, 22.5% protein) or high fat diet group (FAT n=8) in which animals were fed 24.3% carbohydrate, 52.8% fat, 22.9% protein. At the end of the 8 weeks of experimental period, red vastus lateralis muscle was dissected out from all animals, and PPAR ${\alpha},\;{\beta}/{\delta},\;{\gamma}$ mRNA expression was determined. There was no significant difference in body mass (BM) between CHOW and FAT. As expected, blood glucose and free fatty acid (FFA) concentration was higher in FAT than CHOW (p<0.05), and lactate concentration was significantly lower in FAT compared to CHOW (p<0.05). Insulin concentration tended to higher in FAT than CHOW ($67.2{\pm}21.9\;vs.\;27.0{\pm}5.2$ pmol/L), but it did not reach to the statistical significance. Gene expression of PPAR ${\alpha}$ was not significantly different between CHOW and FAT. It was not also significantly different in PPAR ${\beta}/{\delta}$. Interestingly, expression of mRNA in PPAR ${\gamma}$ however, was markedly depressed in FAT compared to CHOW (approximately 3 fold higher in CHOW; p<0.05). Results obtained from present study implies that PPAR ${\gamma}$ (as compensatory function of PPAR ${\alpha}$ is expressed) possibly exerts another major tuning roles in fatty acid transport, utilization, as well as biosynthesis in skeletal muscle cells. The situations and conditions that can be postulated for this implication need to be further examined.

• The Journal of Korean Physical Therapy
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• 제20권3호
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• pp.29-34
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• 2008

Purpose: The purpose of this study was to identify the effect of anterolateral (45$^{\circ}$) and lateral (90$^{\circ}$) direction resistance, with using an elastic band, on the electromyographic(EMG) activity ratio of the vastus medialis oblique (VMO) and the vastus lateralis (VL) during squat exercise. Methods: The study subjects were 19 active people with no history of patellofemoral pain, limitation of range of motion or pain when performing squat exercise. A 'repeated measures within subjects' design was used. The subjects were asked to perform three repetitions of a 90$^{\circ}$ knee flexion squat exercise with anterolateral (45$^{\circ}$) and lateral (90$^{\circ}$) resistance and without resistance, respectively. The EMG activity of the VMO and VL were recorded by surface EMG electrodes and the results were normalized by the % MVIC value. Results: Repeated measures ANOVA's revealed that squat exercise with anterolateral (45$^{\circ}$) resistance produced significantly greater VMO/VL EMG activity ratio than that with lateral (90$^{\circ}$) resistance and without resistance (p=.013). Yet the result of contrast testing revealed that squat exercise with lateral (90$^{\circ}$) resistance showed no significant difference of the VMO/VL EMG activity ratio, as compared with squat exercise without resistance (p>0.05). Conclusion: The findings of this study suggest that squat exercise combining anterolateral (45$^{\circ}$) resistance can contribute positively to the patients with patellofemoral pain as they increase the VMO/VL EMG activity ratio.

• 한국전문물리치료학회지
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• 제12권3호
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• pp.22-30
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• 2005

This study was designed to identify the effect of various decline boards and postures of lower extremities on surface electromyographic (EMG) activity of knee muscles during isometric single-leg decline squat exercises. The subjects were twenty young male adults who had not experienced any knee injury and their Q-angles were within a normal range. They were asked to perform single-leg decline squat exercises in five various conditions. The EMG activities of the gluteus maximus (GM), vastus lateralis (VL), vastus medialis (VMO), tibialis anterior (TA), and gastrocnemius (GCM) muscles were recorded in five various single-leg decline squat exercises by surface electrodes and normalized by maximal voluntary isometric contraction (MVIC) values. The normalized EMG activity levels were compared using one-way ANOVA with repeated measures. The results of this study were as follows: 1) Exercises 2 and 4 produced significantly greater EMG activity of VMO than did exercise 1 ($p_{adj}$<.05/10), 2) The VMO/VL ratio of EMG activity of exercise 4 was the highest, producing a significantly greater ratio than exercise 1 ($p_{adj}$<.05/10). These results show that single-leg lateral oblique decline squat exercise is the best exercise for selective strengthening of VMO, and the posture of the contralateral leg does also affect strengthening of VMO, but we'll need to research patellofemoral joint compression for clinical application of single-leg lateral oblique decline squat exercises.