Earticle

본 연구는 환자 구강내의 상악 우측 대구치 구개면 직접시진 시 환자 머리 각도의 변화에 따른 술자(치과위생사)의 목 주변 근육 활성도의 관련성을 알아보고자 하였다. 술자는 해당부위의 위치와 손고정, 기구 사용에 대한 정확한 이해와 인지를 하고 있는 예비 치과위생사인 치위생학과 4학년 학생들로 표면 근전도, 목 각도계를 이용하여 목 주변 근육 활성도 변화의 자료를 수집하여 SPSS statistics 20을 이용해 Shapiro-wilk 검정, 일원배치 분산분석의 통계처리를 실시하였다. 연구결과 환자 머리의 각도를 주었을 때 각도를 주지 않은 자세 보다 술자의 위등세모근, 목세움근, 어깨올림근 근활성도가 모두 유의하게 감소하였다. 술자의 머리 각도는 환자 머리 각도를 준 자세가 머리 각도를 주지 않은 자세 보다 머리 굽힘은 유의하게 감소하였다. 결과적으로 치아 처치 시 환자 머리 각도의 변화를 주는 것은 술자의 목 주변 근육의 과도한 근활성 도를 줄이고 근육 피로도를 낮출 것으로 예상됨으로 치아 처치 시 환자의 머리 각도 변화의 시행을 추천한다. 이는 잘못된 자세의 반복행위로 인한 근육의 통증도 줄일 수 있을 것이라 사료된다.

This study aimed to investigate the association of the muscle activity around the neck of the operator(dental hygienists’) according to the change in the patient’s neck angle during a direct visual inspection on the maxillary right-side molar palatal surface. The operators were 4thyear dental hygiene students, who are future dentalhy gienists, having accurate understanding on and awareness of the location of the operation site, hand fixation, and how to use the tools. Data on the change in the muscle activity around the neck were collected by using surface electromyography and neck goniometer. SPSS statistics 20 was used for statistical analyses including Shapiro-wilk test and one-way ANOVA. As a result, the activities of the operator upper trapezius, cervical erector spinae, and levator scapulae muscles significantly decreased when the patient’s head was angled compared to when it was not. For the angle of the operator head, the head bend significantly decreased when the patient’s head was angled than when it was not. Based on the study results, it is expected that angling the patient’s head when treating his or her teeth will decrease the excessive muscle activity around the neck of the operator, and will reduce muscle fatigue. Therefore, angling the head of the patient while treating his or her teeth is recommended. This suggests that muscle pain caused by repetitive actions in the wrong posture can be reduced.

Although instrument playing-based training has been repeatedly report-ed to improve functional hand movements including grasping, the at-tempts to present quantitative information on physiological mechanism of grasping have been relatively insufficient to determine the type and the intensity of the exercises involved. This study aimed to examine the muscle activation during hand percussion playing depending on the grasping type and the playing tempo. A total of twelve healthy older adults with a mean age of 71.5 yr participated in this study. Surface electrodes were placed on three grasping-related muscles: Flexor digi-torum superficialis, extensor digitorum, and flexor pollicis brevis. Partic-ipants were instructed to play with the egg shaker, paddle drum mallet and clave involving different types of grasp at three different tempi (i.e., 80, 100, and 120 bpm) and sEMG data were collected during each play-ing. Significantly greater muscle activation was generated with the small sphere type of egg shaker, compared to the handle type of paddle drum mallet and the small cylinder type of clave. Playing at faster tempo also elicited significantly greater muscle activation than at slower tem-po. With regard to the rise time of muscle activation, while tempo sig-nificantly affected the rise time, the time to peak muscle activation did not significantly change depending on the grasping type. This study confirmed that grasping pattern and the tempo of movement signifi-cantly influence the muscular activation of grasping involved in instru-ment playing. Based on these results, clinical implication for instrument selection and structured instrument playing would be suggested.

근전도란 근세포가 흥분하여 수축작용을 일으킬 때 발생하는 미세한 활동전위을 증폭시켜 기록한 것으로 근활동상태나 그 근간이 되는 중추신경의 지배 상황을 파악할 수 있고 이를 시각적 정보로 기록할 수 있다는 특성을 지니고 있어 근 신경계에 관련된 질환의 진단과 처치효과 검증 등 임상학적인 측면에서 뿐 만 아니라, 운동제어, 생체역학, 운동 생리학의 연구분야 등의 운동관련 스포츠 과학자들이나 물리치료사들에게 바이오피드백, 근육의 기능해부학, 그리고 운동단위의 활성화특성 등을 연구하는 데 사용되어져 왔다. 그러나 근전도로부터 정확한 정보를 얻기 위해서는 근전도신호의 근원과 그것의 측정과 신호처리에 관계된 다양한 요소들을 정확하게 이해하지 않으면 근전도 신호로부터 정확한 정보를 얻을 수 없다. 본 논문은 근전도신호의 정확한 측정과 신호처리과정 및 분석평가와 관련된 다양한 고려점들과 원리를 제공하여 보다 정확하고 신뢰성 있는 근전도신호사용과 그 이해를 돕는데 있다.

Electromyography is muscle contraction signal which can be obtained by amplifying a tiny action potential of muscle membranes. It is considerable interest to exercise scientists, physical therapists, and otherclinicians because it is a direct representation of the outflow of motor neurons in the spinal cord to the muscle as a result of voluntary or reflex activation. Electromyography can be used by physical therapists and exercise scientists to study biofeedback, functional anatomy of muscle, firingcharacteristics of motor unit. This information can then be used to guide evaluation of neuromotor function and treatment that may be aimed at either increasing the contraction force of muscle or relaxing muscle. Upto date, even though it provides many important and useful applications, it has many limitations that must be understood considerations in other to obtain correct information. The purpose of this paper is to review and discuss some of the issues involved in recording and interpreting surface EMG data.

본 연구는 벤치프레스 운동 시 탄성 바의 길이에 따른 몸통과 어깨 안정화 근육의 활성도를 표면 근전도(sEMG)를 이용하여 비교 분석하는 것을 목적으로 하였다. 이를 위해 20대 남성 14명을 연구대상으로 선정하였으며, 연구대상자는 각각 200 cm (3.5kg), 220 cm (4kg), 240 cm(4.5kg) 길이의 탄성 바를 사용하여 자신의 1RM의 60% 부하로 8회 반복하는 벤치프레스 운동을 수행하였다. 근육 활성도 측정을 위해 몸통 부위의 배곧은근과 배바깥빗근, 어깨 부위의 어깨세모근 앞쪽 섬유와 뒤쪽 섬유를 선정하였다. 자료처리를 위해 SPSS Win ver. 28.0 프로그램을 사용하여 유의수준 p<.05에서 일원배치 분산분석(ANOVA)을 실시하였다. 연구 결과, 240 cm 탄성 바를 사용한 경우 배곧은근, 배바깥빗근, 어깨세모근 전부(양측)에서 200 cm 및 220 cm 탄성 바보다 유의미하게 높은 근육 활성도를 보였다. 그러나 어깨세모근 뒤쪽섬유에서는 통계적으로 유의한 차이가 나타나지 않았다. 따라서 본 연구는 240 cm 길이의 탄성 바가 벤치프레스 운동 시 몸통과 어깨 부위의 안정화 근육 활성화에 더 효과적임을 제시하며, 이는 운동 및 재활 프로그램 설계 시 유용한 자료로 활용될 수 있을 것이다.

Objectives This study aimed to compare and analyze the activation of stabilization muscles in the trunk and shoulder during the bench press exercise using surface Electromyography (sEMG) based on the length of elastic bars. Methods Fourteen male participants in their 20s (Age: 21.35±0.72 years, Height: 174.42±5.05 cm, Weight: 76.85±9.26 kg) were recruited as participants. Bench press exercises were performed using elastic bars with lengths of 200 cm, 220 cm, and 240 cm. Each participant performed the bench press with a load of 60% of their one-repetition maximum (1RM) for eight repetitions. sEMG was used to measure muscle activation. The selected muscles included the external oblique and rectus abdominis for the trunk, and the anterior and posterior fibers of the deltoid for the shoulder. Statistical analysis was conducted using one-way ANOVA with a significance level of .05. Results The comparison of muscle activation using sEMG across the three elastic bar lengths 200 cm(3.5kg), 220 cm(4kg), and 240 cm(4.5kg) revealed that the 240 cm bar resulted in significantly higher activation of the rectus abdominis, external oblique, and anterior fibers of the deltoid (bilaterally) compared to the 200 cm and 220 cm bars. However, no statistically significant differences were observed in the posterior fibers of the deltoid bilaterally. Conclusions The comparative analysis of three elastic bar lengths during the bench press exercise showed that the 240 cm bar elicited greater activation of the rectus abdominis, external oblique, and anterior fibers of the deltoid (bilaterally) than the 200 cm and 220 cm bars. These findings suggest that the 240 cm bar is more effective in activating stabilization muscles in the trunk and shoulder regions.

Gender differences have been studied by using spectral features and time features such as median frequency (MDF) and root mean square (RMS) in surface EMG signals during static exercise. MDF is the most commonly used as a feature to describe muscle conduction velocity. However, during dynamic exercise in daily life, the estimate of these features are difficult to indicate gender effects because of its instability and high standard deviation. The aim of this paper is to detect gender different characteristics from surface EMG signals during isotonic contractions as a dynamic exercise of the bicep Brachii. Eight volunteers (four females and four males) participated in this experiment to record surface EMG placed on the biceps brachii and each recording experiment continued until their endurance time. To find gender differences, we used feature values and regressive slopes of surface EMG and compared the feature changes from the onset to the endurance time of isotonic contractions. The result of experiments shows that the significant differences between males and females are not in the values of MDF and RMS (P>0.05) but in the slopes of them up to the endurance time (P<0.05). Therefore, the regressive slope of these features is valid to measure gender differences.

This study was conducted to identify Dynamic Surface EMG activities of back muscle, gluteus maximus, hamstring muscles in 20 adult men and women who simulated leg length difference. Subjects were healthy 20 adults who have no back pain and orthopaedic problems. The measurement tools used Myotronics-Noromed MES 9000 EMG and thickness used each 2, 3, 4cm scaffold, protractor, micro- chronometer etc. Surface EMG activities were recorded during active trunk flexion(0˚, 45˚, 90˚) in stand position. Next, Surface EMG activities were recorded during active trunk flexion according to scaffold height on left leg(each 2, 3, 4cm). Analysis method enforced Two-way repeated ANOVA. The results were as follows. 1) According to increase height of left leg, Surface EMG activities of left back muscle and right gluteus maximus were increased, Surface EMG activities of right back muscle and left gluteus maximus were looked inclination that decrease generally but it was no statistical significance(p > 0.05). 2) During the trunk 45˚, 90˚ flexion, Surface EMG activities of almost all muscle were increased. Specially, Surface EMG activities of back muscles was the highest during the trunk 45˚ flexion. However, Surface EMG activities of back muscle of the trunk 90˚ flexion were lower than that trunk 45" flexion. And, Surface EMG activities of gluteus maximus were the lowest to increased leg length.

표피 근전도의 전력스펙트럼은 근섬유의 전도속도의 활성에 의존하기 때문에 표피 근전도 신호 주파수 파 라미터들의 신뢰성 평가는 임상에서 매우 중요하다. 본 연구의 목적은 노인들의 근피로지수 개발을 위한 표피 근전도 주파수파라미터들의 지속적인 측정들의 신뢰성을 조사하는 것이다. 본 실험에 자원한 10명의 건강한 피검자들은 위팔두갈래근의 최대수축운동 20% 강도의 부하로 수행하였다. 그리고 1회분의 시험세트를 마친 후 2시간의 휴식기간을 취하고 다음 2회분의 시험세트를 수행하였으며 마찬가지로 동일한 휴식시간을 취한 후 3회분의 시험세트를 수행하였다. 평균전력주파수의 표준오차 0.08～1.98은 중앙주파수 0.13～2.27보다 작게 나 타났다. 그리고 1회분과 2회분 평균전력주파수의 피어슨상관계수는 0.54～0.89이고 다른 회보다 높게 나타났 다. 그러므로 본 연구결과에서 평균전력주파수는 근피로를 위한 유의한 주파수파라미터임을 확인하였다.

Assessment of the repeatability for frequency parameters from surface EMG signal (sEMG) is of considerable relevance for the clinical usage, because the power spectrum of sEMG explicitly depends on the conduction velocity of muscle fiber. The purpose of the present study was to examine the reliability of repeated measurements in sEMG frequency parameters during isotonic contractions for Muscle Fatigue Index development of old person. Ten healthy subjects performed voluntary isotonic contractions of biceps Brachii muscle until exhaustion at 20% of maximal voluntary contraction level, three test sets a day with two hours of rest. The standard error of measurements for mean power frequency (0.08-1.98) were less than those for median frequency (0.13-2.27). The Pearson correlation coefficients of mean power frequency between the first and the second set were significantly higher (0.54-0.89) than the others. Therefore, the experimental results show that mean power frequency could provide a reliable frequency parameter to assess muscle fatigability.

The electrocardiography (ECG) artifact corrupts the surface electromyography (sEMG) signals recorded from the trunk area We assessed the effectiveness of three methods used to remove the ECG. We compared the performance of bandpass filtering methods, the commonly used mathematical morphology operator (MMO) method and the Adaptive filter on both simulationed and real sEMG data. False positive and false negative errors increased with larger ECG to EMG ratios for all 3 methods. However, the Adaptive filter showed better performance as compared to bandpass filtering and the MMO particularly for low signal-to-artifact ratios of a lower computational load.

Surface electromyography (sEMG) is a noninvasive method used to capture electrically muscle activity, which can be easily measured even during exercise. The basic unit of muscle activity is the motor unit, and because an sEMG signal is a superposition of motor unit action potentials, analysis of muscle activity using sEMG should ideally be done from the perspective of motor unit activity. However, conventional techniques can only evaluate sEMG signals based on abstract signal features, such as root-mean-square (RMS) and mean-power-frequency (MPF), and cannot detect individual motor unit activities from an sEMG signal. On the other hand, needle EMG can only capture the activity of a few local motor units, making it extremely difficult to grasp the activity of the entire muscle. Therefore, in this study, a method to visualize the activities of motor units in a single-channel sEMG signal by relocating wavelet coefficients obtained by redundant discrete wavelet analysis is proposed. The information obtained through this method resides in between the information obtained through needle EMG and the information obtained through sEMG using conventional techniques.

Robot-assisted self-rehabilitation for patients with stroke is significant for their motor recovery. Meanwhile, the surface EMG can reflect human neuromuscular activity and can be used for rehabilitation robot control. In this paper, we propose a Two-Step SVM classification method based on One-versus-One SVM muti-class classification method in order to improve the time efficiency of upper limb motion classification by sEMG, and then promote the real- time control of upper limb rehabilitation robot. A control experiment is done between the Two-Step SVM classification method and the One-versus-One SVM method. Four muscles in human upper limb are chosen to train and six motions are to recognize according to the aim of rehabilitation and the characteristic of people’s daily life. The classifier training and motion recognize times between these two methods are compared. The result shows, the Two-Step SVM classification method proposed is improved in time efficiency, which is meaningful to improve the real time control of the robot during the process of rehabilitation.

An implementation for surface EMG network analysis and vertical control system of robotic arm is presented in this paper. The transmembranes are simulated by equivalent circuit and cable equation for propagation to be converted to circuit networks. The implementation is realized to be derived from the detecting EMG signal from 3 electrodes, and EMG transmembrane signals of human arm muscles are detected by several surface electrodes, high performance amplifier and filtering, converting analog to digital data and driving a servomotor for spontaneous robotic arm. The system is experimented by monitoring multiple steps vertical control angles corresponding to biceps muscle movement. The experimental results are that the vertical moving control level is measured to around 2 degrees and mean error ranges are lower 5%.

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The aim of this study was to examine the characteristics in duration and amplitude of the submental muscle activities during dry and wet swallowing. We examined the middle suprahyoid muscle activities in 32 normal adult women during three swallowing conditions, that is, dry as well as 5 mL & 10 mL water swallowings, using a surface EMG. From the results, there were significant differences in duration: the longest in dry swallowing and shortest in 5 mL water swallowing. However, the mean amplitude per msec increased as the duration decreased. This may imply motor equivalence in swallowing stating that duration and amplitude are complementary in order to achieve a given swallowing goal.

The present study was performed to investigate the effect of aging on muscular activity of older subjects under the condition of fixed load muscle contraction. SEMG signals were recorded from old (46 women) and young (45 women) groups performing sustained isometric elbow flexion contraction with a fixed load during 30 seconds. Linear regression and mean square error (MSE) analysis with four characteristic variables (ARV, RMS, MDF, MNF) were used to compare the age-related difference (of local muscle fatigue and fluctuation of the amplitude and frequency) in the SEMG signal. The main results can be summarized as follows: During sustained muscle contraction with a fixed load: i) the MSE values of amplitude (ARV, RMS) and frequency (MDF, MNF) variables were more than 30% higher for the young than for the old adults; ii) the measures of local muscle fatigue (slope of the MDF and MNF) indicated greater fatigue in the old; and iii) the rate of increase of the SEMG amplitude was higher for the young than the old.

성악발성 시 전문적인 성악가와 비전문가에서 성대외근의 수축 경향을 파악함으로써, 성대외근이 성악발성에 갖는 중요성을 파악하고, 얻어진 자료를 토대로 성악발성 숙련도의 판정이나 성악인의 음성치료에 활용할 수 있는 가능성을 알아보고자 하였다. 서양음악을 전공한 지 10년 이상 된 20-30대의 소프라노 4인을 성악가 군으로, 비전공자 여성 4인을 대조군으로 하여, E3 부터 C6 내의 9개 음을 낮은 음부터 시작하여 차례로 /이/ 모음을 수초간 발성하게 하였다. Multi-Mode Program (UP) Plus (Nicolet, Viking IV)와 1개 채널의 음성신호 및 3개 채널의 surface electrode를 이용하여 발성 시설골상근, 설골하근, 견갑설골근의 활동전위를 측정한 뒤, 단위시간 당 근전위 진폭의 합을 구하여 두 군간에 그 양상을 비교하였다. (중략)

저작근과 관련하여 나타나는 여러 운동장애의 치료나 심미적인 목적으로 교근 부위에 보툴리눔 독소를 주사하는 방법이 널리 이용되고 있다. 그러나 보툴리눔 독소의 교근 부위 주사가 다른 저작근의 근전도와 악기능에 어떠한 영향을 미치는 지에 대한 자료는 부족하다. 이에 본 연구에서는 측두하악관절장애 등 하악의 기능 이상을 가지고 있지 않는 건강한 성인남녀 14명을 대상으로 양측 교근에 각각 80 unit씩의 보툴리눔 독소 A(Dysport, Ipsen, Wrexham, UK)를 주사한 5 명의 실험군과 같은 위치에 같은 양의 생리식염수를 주사한 9 명의 대조군에서 주사 전과 주사 후 3 주까지 매주 교근과 전측두근의 표면 근전도를 측정하고, 국문판 악기능제한지수(Jaw Functional Limitation Scale) 설문지를 이용하여 악기능제한 정도를 평가하여 비교 분석하였다. 교근의 근전도는 실험군에서 주사 후 1주부터 감소하기 시작하여 3주 동안 지속적인 감소를 나타냈으며, 전측두근의 근전도는 유의한 변화를 나타내지 않았다. 악기능제한지수는 저작지수와 전반적 악기능 지수가 실험군에서 보툴리눔 독소 주사 후 1 주째에 증가한 뒤 점차 회복하는 양상을 보였으며, 개구지수와 대화 및 감정표현 영역 기능제한지수는 통계적으로 유의한 변화를 보이지 않았다. 이러한 결과로부터 교근에 시행하는 보툴리눔 독소 주사는 교근의 활성을 지속적으로 저하시키지만 전측두근의 활성에는 영향을 미치지 않았으며, 주관적 저작기능을 단기적으로 저하시키나, 근활성의 저하가 지속되는 과정에서도 주관적 저작기능은 짧은 기간 내에 회복됨을 알 수 있었다.

Botulinum toxin injection has been used in the masticatory muscle area as an effective treatment method of various movement disorders and facial contouring, but its effects on jaw function have not been evaluated. The aims of this study were to evaluate the effects of botulinum toxin type A injection into the masseter muscle on the EMG activities of masseter and anterior temporal muscles, and the limitation of jaw function. Fourteen healthy subjects were recruited. Five subjects were injected with 80 units of botulinum toxin type A(Dysport, Ipsen, Wrexham, UK) into each side of masseter muscle, and nine subjects were injected with saline into the same site as the botulinum toxin group. The surface EMG activities at maximum voluntary contraction of masseter and anterior temporal muscles were recorded before, 1 week, 2 weeks, and 3 weeks after injection. Presence of jaw functional limitations in each subject was investigated using Korean version of Jaw Functional Limitation Scale(JFLS) questionnaire. The masseter muscle EMG was gradually decreased in the botulinum toxin group comparing with that of the control group(p<0.001), but the anterior temporal muscle EMG did not show significant changes. There was significant increases in the mastication (p<0.01), and global jaw limitation(p<0.05) subscales of JFLS at 1 week after injection, but no significant changes in the other subscales including opening, and verbal and emotional expression during the recording periods. Our results suggest that botulinum toxin injection into masseter muscle can affect modest limitation in mastication function at 1 week after injection but recovered to the baseline until 3 weeks after injection. The EMG activity of masseter muscle had been gradually decreased until 3 weeks after botulinum toxin injection but the anterior temporal muscle did not show any significant changes.

A visual decision by clinical experts like physical therapists is a best way to detect onset and offset time of muscle activation. The current computer-based algorithms are being researched toward similar results of clinical experts. The new algorithm in this paper has an ability to extract a trend from noisy input data. Kalman smoother is used to recognize the trend to be revealed from disorderly signals. Histogram of smoothed signals by Kalman smoother has a clear boundary to separate muscle contractions from relaxations. To verify that the Kalman smoother algorithm is reliable way to detect onset and offset time of muscle contractions, the algorithm of Robert P. Di Fabio (published in 1987) is compared with Kalman smoother. For 31 templates of subjects, an average and a standard deviation are compared. The average of errors between Di Fabio's algorithm and experts is 109 milliseconds in onset detection and 142 milliseconds in offset detection. But the average between Kalman smoother and experts is 90 and 137 milliseconds in each case. Moreover, the standard deviations of errors are 133 (onset) and 210 (offset) milliseconds in Di Fabio's one, but 48 (onset) and 55 (offset) milliseconds in Kalman smoother. As a result, the Kalman smoother is much closer to determinations of clinical experts and more reliable than Di Fabio's one.

The voluntary EMG (vEMG) signal from electrically stimulated muscle is very useful for feedback control in functional electrical stimulation. However, the recorded EMG signal from surface electrodes has unwanted stimulation artifact and M-wave as well as vEMG. Here, we propose an event-synchronous adaptive digital filter for the suppression of stimulation artifact and M-wave in this application. The proposed method requires a simple experimental setup that does not require extra hardware connections to obtain the reference signals of adaptive digital filter. For evaluating the efficiency of this proposed method, the filter was tested and compared with a least square (LS) algorithm using previously measured data. We conclude that the cancellation of both primary and residual stimulation artifacts is enhanced with an event-synchronous adaptive digital filter and shows promise for clinical application to rehabilitate paretic limbs. Moreover because this algorithm is far simpler than the LS algorithm, it is portable and ready for real-time application.

Many researchers had examined the validity of using the high-to-low ratio between two fixed frequency band amplitudes (H/L-FFB) from the surface electromyography of a face and body as the first spectral index to assess muscle fatigue. Despite these studies, the disadvantage of this index is the lack of a criterion for choosing the optimal border frequency. We tested the potential of using the high-to-low ratio between two signal spectral moments (H/L-SSM), without fixed border frequencies, to evaluate muscle fatigue and predict endurance time ($T_{end}$), which was determined when the subject was exhausted and could no longer follow the fixed contraction cycle. Ten healthy participants performed five sets of voluntary isotonic contractions until they could only produce 10% and 20% of their maximum voluntary contraction (MVC). The $T_{end}$ values for all participants were $138{\pm}35s$ at 10% MVC and $69{\pm}20s$ at 20% MVC. Changes in conventional spectral indices, such as the mean power frequency (MPF), Dimitrov spectral index (DSI), H/L-FFB, and H/L-SSM, were extracted from surface EMG signals and were monitored using the initial slope computed every 10% of $T_{end}$ as a statistical indicator and compared as a predictor of $T_{end}$. Significant correlations were found between $T_{end}$ and the initial H/L-SSM slope as computed over 30% of $T_{end}$. In conclusion, initial H/L-SSM slope can be used to describe changes in the spectral content of surface EMG signals and can be employed as a good predictor of $T_{end}$ compared to that of conventional spectral indices.

We present a method for the estimation of intramuscular electromyographic(EMG) signals from the given surface EMG signals. This method is based on representing the surface EMG signal as an autoregressive(AR) time model with a delayed intramuscular EMG signal as an input. The parameters of the time series model that transforms the intramuscular signal to the surface signal are identified. The identified model is then used in estimating the intramuscular signal from the surface signal.