• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.799-804
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• 1991

This paper is concerned with the artificial control of prosthetic devices using the electromyographic(EMG) activities of biceps and triceps in human subject during isometric contraction adjustments at the elbow. And it was analysised about recognition of EMG signals and dynamic characteristics at arm movements of human. For this study the error signal of autoregressive(AR) model were used to discriminate arm movement patterns of human. Interaction of dynamic characteristics (Position, Velocity, Acceleration) and EMG of biceps and triceps at arm movements of human was measured.

• 전기학회논문지
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• 제67권1호
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• pp.124-130
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• 2018

The EMG amplitude estimator, which has been investigated as an indicator of muscle force, is of high relevance not only in biomechanical studies but also more and more in clinical applications. This paper presents a new approach to estimate surface EMG amplitude by using the mean spike and mean turn amplitude(MSA and MTA) variables. Surface EMG signals, a total of 198 signals, were recorded from biceps brachii muscle over the range of 20-80%MVC isometric contraction and performance of the MSA and MTA variables applied to amplitude estimation of the EMG signals were investigated. To examine the performance, a SNR(signal-to-noise ratio) was computed from each amplitude estimate. The results of the study indicate that MSA and MTA amplitude estimations with first order whitening filter and 300[ms]-350[ms] moving average window length are optimal and show better performance(mean SNR improvement of 6%-15%) than the most frequently used variables(ARV and RMS).

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1600-1602
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• 2008

Various applications of exoskeleton system are reported in the area of military, healthcare, and industries. More the user gets help from exoskeleton system, more power is consumed. To resolve this design conflict, we suggest an energy efficient exoskeleton system which compensates muscle fatigue in isotonic and isometric contraction conditions. Fatigue compensated exoskeleton significantly reduced muscle fatigue while consumed less operation power. In addition, the level of fatigue compensation can be managed by motor control using various input profile. It can make user customized exoskeleton system.

• 대한물리의학회지
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• 제1권1호
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• pp.37-47
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• 2006

Purpose : The purpose is to assess the effects of muscle activity of normal person with contact laterally wedged insoles with strapping of varying elevations of 9, 15, 21mm. Methods : The subjects were adult males and women who had not experienced any knee injury. They were asked to performed from isometric contraction exerciese in four postures using lateral wedged. The normalized EMG activity levels(%MVC) of the vastus lateralis, vastus medialis, tibialis anterior, soleus for the four postures of the lower extremities were compared using one way repeted measures ANOVA. Results : Comparison of EMG amplitudes across all postures revealed no significant differences among all muscles(P>0.05). Conclusion : Further studies of the effect of wedged insole angle on knee varus torque in patients with medial-lateral knee osteoarthritis are needed.

• 대한물리치료과학회지
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• 제21권1호
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• pp.13-20
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• 2014

Purpose : The purpose of this study was to analyze and compare the surface electromyography(EMG) activity of trunk region muscle between normal subjects and chronic low back pain(CLBP) patients during one leg stance. Methods : The subjects were 27 people, were consisted of 12 subjects who don't have low back pain and 15 subjects who have low back pain from 19 to 28 year of age(mean age 22.22). We used surface EMG to evaluate the activity of the Rectus abdominis, External abdominal oblique, Quadratus lumborum, Gluteus medius muscle. We used independent two samples t-test for statistical data. Results : The result of this study showed that the maximal voluntary isometric contraction(%MVIC) ratio of the trunk muscles was higher in patients with CLBP than in normal subject. But there were no statistically significant differences. There were statistically significant differences of the activity of the Quadratus lumborum, Gluteus medius muscle(p<0.05).

• 대한전기학회논문지:시스템및제어부문D
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• 제52권9호
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• pp.560-567
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• 2003

EMG recordings of the electrical activity of muscle have proved to be a valuable tool in studying muscle function and reflex activity. SP(silent period) is elicited by a electrical stimulation on the chin during isometric contraction of jaw muscle. This paper proposes a model of the inhibitory reflex mechanism of jaw muscle after electrical stimulation. The SPs of jaw muscle after a electrical stimulation to the chin were divided into SP1 and SP2. SP1 is produced by the activation of periodontal receptors. The activation of nociceptors contributes to the SP2. As a result, the EMG signal generated by a proposed a model of inhibitory reflex mechanism is similar to real both EMG signal including SP1 and SP2. The present study have shown differences of SP1 and SP2 induced by inhibitory reflex mechanism.

• The Korean Journal of Physiology
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• 제21권2호
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• pp.259-272
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• 1987

This was study carried out to investigate the effect of calcium on spontaneous contraction and electrical activity induced by ethanol in gastric smooth muscle. After peeling off the mucous membrane from the isolated whole stomach of 102 cats, two kinds of small muscle preparations $(2.0{\times}0.2\;cm)$, one longitudinal and the other circular, were excised from the fundus, the corpus and the antrum portion of each whole stomach specimen. The isometric contraction of the small muscle preparation was measured in a cylinder-shaped chamber filled with Krebs-Ringer-dextrose solution (pH 7.4, temperature $36{\pm}0.5^{\circ}C$) bubbling with 5% $CO_2$ in $O_2$. A large muscle preparation $(5.0{\times}1.2\;cm)$ was excised from the anterior wall of the corpus-antrum portion of the same specimen in 72 of 102 cats. The gastric electrical activity (slow wave and spike potential) was monopolarly recorded by four capillary electrodes (Ag-AgCl), of which two were placed on the corpus and two on the antrum, in a muscle chamber filled with the same solution as described above. Changes in the amplitude of the contraction, frequency of the gastric slow wave and the production of the spike potential were observed after adding ethanol and/or under the treatments with verapamil, $CaCl_2$ and Ca-free Krebs-Ringer-dextrose solution. The results were as follows: 1) After adding ethanol, the spontaneous phasic contraction of the corpus was reduced dose-dependently (0.125-2.0%), which was totally abolished by higher concentrations (2.0-8.0%) of ethanol. 2) The corporal phasic contraction was also completely abolished by verapamil $(3{\times}10^{-5}\;M)$ or Ca-free Krebs-Ringer-dextrose solution. The contraction was increased by $CaCl_2\;(1.8{\times}10^{-3}\;M)$, but the inhibitory effect of ethanol on the contraction persisted even under the treatment with $CaCl_2$. 3) At higher concentrations, ethanol caused tonic contraction of both preparations from the fundus, the corpus and the antrum in a dose-dependent manner. The tonic contraction of the fundus produced by ethanol was not influenced by $CaCl_2$ or verapamil, whereas the tonic contraction was not produced by ethanol in tile Ca-free solution. 4) Frequency of gastric slow wave was decreased dose-dependently by the addition of ethanol (0.25-1.0%), and tile slow wave was not produced by higher concentration of ethanol (2.0%). 5) The frequency of slow wave was significantly reduced by verapamil only and the inhibitory influence of ethanol on the slow wave frequency was reinforced by verapamil. 6) The treatment of $CaCl_2$ increased significantly the slow wave frequency, and attenuated the inhibitory effect of ethanol on the frequency. It is therefore suggested that ethanol regulates the phasic contraction and the production of slow wave by interfering with the transport of calcium in the stomach muscle of the cat.

• The Korean Journal of Physiology and Pharmacology
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• 제4권5호
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• pp.369-378
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• 2000

This study was undertaken to investigate an involvement of nitroxergic innervation in gastric smooth muscle of rat. Isometric tension study, the measurement of single cell length, NADPH diaphorase stain of smooth muscle layers and neuronal nitric oxide synthase (nNOS) western blotting were performed. Sodium nitroprusside (SNP), a nitric oxide donor, relaxed the muscle strips precontracted by acetylcholine (ACh) in a concentration-dependent manner. Pretreatment of L-arginine decreased the contraction induced by electric field stimulation (EFS). Pretreatment of $N^G-nitro-L-arginine$ methyl ester (L-NAME), a NOS inhibitor, increased the EFS-induced contractions. LY 83583, a guanylate cyclase (GC) inhibitor, reversed the inhibitory actions of L-arginine on the muscle contractions. The effects of L-Arginine, L-NAME and LY 83583 on ACh-induced contractions were not significant. L-arginine reduced the EFS-induced contraction in circular muscle, whereas L-NAME enhanced the EFS-induced contraction in longitudinal strips. By EFS, the phasic contractions appeared approximately $20{\sim}25$ seconds later. L-NAME significantly shortened the delay time to about $2{\sim}3$ seconds. In single cell study, ACh contracted gastric smooth muscle cells, SNP relaxed the cells, and the latter also inhibited the ACh-induced contraction. LY 83583 enhanced the ACh-induced contraction and antagonized SNP-induced relaxation. NADPH diaphorase activity was assessed by a histochemistry, nitroblue tetrazolium (NTB) staining. Positive staining was observed in both circular and longitudinal muscle layers. L-arginine increased the staining, while L-NAME decreased the staining. Western blotting for nNOS proved the presence of nNOS in rat gastric smooth muscle. EFS and additional $Ca^{2+}$ increased nNOS protein expression. These results suggest that in rat stomach, both circular and longitudinal muscle layers are innervated with nitroxergic nerves which relax the gastric smooth muscle via NO-cGMP pathway.

• 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.

• The Journal of Korean Physical Therapy
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• 제20권4호
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• pp.35-42
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• 2008

Purpose: Alterations in the structure and function of vascular smooth muscle cells (VSMCs) are important in cardiovascular disease and maintaining chronic hypertension. Chronic hypertension is associated with changes in vascular smooth muscle tone. The spontaneous or myogenic tone of a blood vessel reflects the ability to adapt smooth muscle tone to changes in transmural pressure. However, the intracellular signaling mechanisms involved in myogenic tone are not fully understood. Methods: Here, we investigated the relationship between mitogen-activated protein kinases (MAPKs) and phosphatidylinositol-3 kinase (PI3K) in isometric contraction and enzymatic activity using muscle strips from rats made hypertensive with aldosterone-analogue deoxycorticosterone acetate (DOCA) salts. Results: Changes in myogenic tone and intracellular $Ca^{2+}$ concentration ($[Ca^{2+}]_i$) were different after physiological salt solution (PSS) in normotensive and hypertensive rats. The myogenic tone and quiescent phosphorylation induced by the PSS treatment were inhibited by 10 ${\mu}$M PD098059, an extracellular-regulated protein kinase 1/2 (ERK1/2) inhibitor, and 10 ${\mu}$M wortmannin, an inhibitor of PI3K, in hypertensive rats. Conclusion: The development of DOCA-induced hypertension is associated with altered isometric contractions and $[Ca^{2+}]_i$ via changes in activation of ERK1/2 and PI3K after DOCA-salt treatment. Therefore, ERK1/2 and PI3K activity affect hypertension and may be suitable targets for physical therapy in cardiovascular disease.