Characteristics of Motoneurons Controlling Single Finger Movement in Different Individuals / 医用生物力学

Objective To analyze characteristics of motoneurons controlling the extension of a single finger in different individuals, and obtain the similarity and difference of micro-motoneurons characteristics in different individuals. Methods The motoneurons were decomposed by blind source separation algorithm. The two dimensional (2D) features of the neurons were quantified, and the fingers were classified by the features of the neurons decomposed by different individuals. In addition, the proportion of shared motor neurons was used to study characteristics of motoneurons innervating the coordinated movement of different fingers between individuals. Results There were significant differences in spatial distribution of motoneurons between the index finger and the middle finger for different individuals, but the activation area was similar. Using data from different people as training sets and testing sets, the average accuracy of finger classification was 86. 99% , and it was significantly improved to 90. 07% after using transfer component analysis (TCA) calibration. Through analysis on the proportion of shared neurons in different individuals, it was found that the proportion of shared neurons between index finger and other three fingers (middle finger, ring finger and little finger) was relatively low, while that between ring finger and little finger was high. Conclusions The spatial discharge characteristics of motoneurons controlling different fingers in different individuals are similar and have small individual differences. This study reveals the internal neural mechanism of different individuals during finger movement, and provides references for clinical neural mechanism analysis of patients with finger movement disorders and the related engineering applications

A new method for high-density surface electromyography decomposition in dynamic muscle contraction / 生物医学工程学杂志

In this paper, a new surface electromyography (sEMG) signal decomposition method based on spatial location is proposed for the high-density sEMG signals in dynamic muscle contraction. Firstly, according to the waveform correlation of each muscle motor units (MU) in each channel, the firing times are extracted, and then the firing times are classified by the spatial location of MU. The MU firing trains are finally obtained. The simulation results show that the accuracy rate of a single MU firing train after classification is more than 91.67%. For real sEMG signals, the accuracy rate to find a same MU by the "two source" method is over (88.3 ± 2.1)%. This paper provides a new idea for dynamic sEMG signal decomposition.

Quantitative Measurement of Laryngeal Electromyography Using Motor Unit Action Potential in Unilateral Vocal Cord Paralysis

BACKGROUND AND OBJECTIVES: Laryngeal electromyography (LEMG) is valuable to evaluate the innervation status of the laryngeal muscles and the prognosis of vocal fold paralysis (VFP). However, there is a lack of agreement on quantitative interpretation of LEMG. The aim of this study is to measure the motor unit action potentials (MUAP) quantitatively in order to find cut-off values of amplitude, duration, phase for unilateral vocal fold paralysis patients. MATERIALS AND METHOD: Retrospective chart review was performed for the unilateral VFP patients who underwent LEMG from March 2016 to May 2018. Patient's demography, cause of VFP, vocal cord mobility, and LEMG finding were analyzed. The difference between normal and paralyzed vocal folds and cut-off values of duration, amplitude, and phase in MUAP were evaluated. RESULTS: Thirty-six patients were enrolled in this study. Paralyzed vocal fold had significantly longer duration (p=0.021), lower amplitude (p=0.000), and smaller phase (p=0.012) than the normal. The cut-off values of duration, amplitude, and phase in MUAP for unilateral VFP were 5.15 ms, 68.35 µV, and 1.85 respectively. CONCLUSION: An analysis of MUAP successfully provided quantitative differences between normal and paralyzed vocal folds. But, additional research is needed to get more available cut-off value which is helpful to evaluate the status of laryngeal innervations.

A new approach for multi-channel surface EMG signal simulation

Simulation models are necessary for testing the performance of newly developed approaches before they can be applied to interpreting experimental data, especially when biomedical signals such as surface electromyogram (SEMG) signals are involved. A new and easily implementable surface EMG simulation model was developed in this study to simulate multi-channel SEMG signals. A single fiber action potential (SFAP) is represented by the sum of three Gaussian functions. SFAP waveforms can be modified by adjusting the amplitude and bandwidth of the Gaussian functions. SEMG signals were successfully simulated at different detected locations. Effects of the fiber depth, electrode position and conduction velocity of SFAP on motor unit action potential (MUAP) were illustrated. Results demonstrate that the easily implementable SEMG simulation approach developed in this study can be used to effectively simulate SEMG signals.

The loss of motor unit and it's influencing factors in patients with middle cerebral artery infarction / 中国神经精神疾病杂志

Objective To investigate the loss of motor unit and it's influencing factors in the lower motor neurons after middle cerebral artery infarction. Method Forty patients with first onset and unilateral middle cerebral artery infarction were divided into cortical-basal ganglia(26)and basal ganglia(14)groups and 10 healthy controls were served as control group.All included patients were scored by National Institute of Health stroke scale(NIHSS),modified Rankin scale (mRS), Fugl-Meyer Assessment (FMA) at 48 hours of admission. Nerve conduction study on the limb and motor unit number estimation (MUNE) on abductor pollicis brevis were performed at 2-4 weeks after onset, and the data of single motor action potential (SMUAP) were collected. SPSS 20.0 software was used to statistical analysis. Result The MUNE on were significantly lower and the amplitude and area of SMUAP were significantly increased in ipsilateral than contralateral sides (cortical-basal ganglia group:95.85±26.82 vs. 143.65±38.86, P<0.001; basal ganglia group: 126.71± 44.13 vs. 157.36±56.72, P=0.001). The affected MUNE was significantly decreased in the cortex-basal ganglia than in basal ganglia groups (95.85±26.82 vs.161.40±48.90,P=0.027). The MUNE was negatively correlated with NIHSS score (r=-0.362,P=0.022)and mRS score(r=-0.339,P=0.032).NIHSS score(β=-1.603,P=0.032,95%CI:-3.064~-0.142)and mRS score(OR=2.885,P=0.025,95%CI:1.139~7.158)on admission could predict the loss of MUNE on the affected side. Conclusion This study reveals the loss of motor unit and the compensation of remained motor unit on the affected side after middle cerebral artery infarction,NIHSS score and mRS score on admission may predict the loss of MUNE after stroke.

Motor-Unit Number Estimation Is Sensitive in Detecting Motor Nerve Involvement in Patients with Carpal Tunnel Syndrome

BACKGROUND AND PURPOSE: We compared the motor-unit number estimation (MUNE) findings in patients who presented with signs and/or findings associated with carpal tunnel syndrome (CTS) and healthy controls, with the aim of determining if motor-unit loss occurs during the clinically silent period and if there is a correlation between clinical and MUNE findings in CTS patients. METHODS: The study investigated 60 hands of 35 patients with clinical CTS and 60 hands of 34 healthy controls. Routine median and ulnar nerve conduction studies and MUNE analysis according to the multipoint stimulation method were performed. RESULTS: The most common electrophysiological abnormality was reduced conduction velocity in the median sensory nerve (100% of the hands). The MUNE value was significantly lower for the patient group than for the control group (p=0.0001). ROC analysis showed that a MUNE value of 121 was the optimal cutoff for differentiating between patients and controls, with a sensitivity of 63.3% and a specificity of 68.3%. MUNE values were lower in patients with complaints of numbness, pain, and weakness in the median nerve territory (p<0.05, for all comparisons), and lower in patients with hypoesthesia than in patients with normal neurological findings (p=0.023). CONCLUSIONS: The MUNE technique is sensitive in detecting motor nerve involvement in CTS patients who present with sensorial findings, and it may be useful in detecting the loss of motor units during the early stages of CTS. Larger-scale prospective clinical trials assessing the effect of early intervention on the outcome of these patients would help in confirming the possible benefit of detecting subclinical motor-unit loss in CTS.

Mechanomyographical signals during prolonged intermittent muscular contractions at low levels under various duty cycles / 体力科学

To obtain one of the possible factors on the abrupt increment of mechanomyographic (MMG) signal during prolonged isometric constant contraction (PICC; <20%MVC), the present study focused on the iMMG changes from m. vastus medialis (VM) and/or lateralis (VL) during the intermittent isometric constant contractions (IICC) at various condition of the duty cycle (or relaxation/contraction ratio: R-C ratio) and the target tension. Target tension set at 5, 10 and 15 %MVC and the duty cycle set at 16s-ON/4s-OFF, 56s-ON/4s-OFF and 116s-ON/4s-OFF. Simultaneous recording of myoelectrical signal (MES) was made on VM and/or VL. 1) IMMG increased weakly and monotonously with the cumulative load which is accumulated the acreage of tension and time through the IICC. Also, iMES sustained or increased weakly but the increment ratio was lower than iMES under PICC condition. 2) The increment ratio of iMMG (or gradient of linear regression formula with the cumulative load: G-iMMG) from both muscles increased depend on the increment ratio of the cumulative load (or gradient of linear regression formula with the time) in the stored data under the IICC conditions. But there could not be seen the distinct relation in that of iMES. 3) The G-iMMG decreased with R-C ratio. But G-iMES did not show distinct relationship with R-C ratio among subjects and between muscles. Linear incremental tendency of iMMG would originate from the inserted muscle relaxation during IICC. Therefore, the abrupt increase of iMMG during PICC suggests to be caused from the continuous muscle contraction itself.

The detection of motor nerve injury by MUNE in an animal model of diabetes / 天津医药

Objective To investigate motor nerve function status in rats with diabetes mellitus by motor unit number estimation (MUNE), and discuss it′s early diagnostic value in diabetic peripheral neuropathy (DPN). Methods Diabetic rat model (DM group) was induced by streptozotocin. The MUNE of gastrocnemius muscle and motor nerve conduction (MCV, CMAP) of the sciatic nerve were measured at the 4th, 8th and 12th week after onset of hyperglycemia in the DM group and the control group (normal SD rats). The ultrastructure of sciatic nerve was observed by electron microscope. Results At the 4th week, MUNE of gastrocnemius muscle was significantly decreased in DM group compared to that of the control group (275.88 ± 87.87 vs 369.71 ± 75.64,P<0.05). There were no significant differences in MCV and CMAP of sciatic nerve be?tween two groups. The electron microscopy observation showed that most nerve fibers were normal;a small amount of axonal atrophy, and myelin lamellar structure was separated in DM group. At the 8th week, compared with the control group, MUNE were reduced in gastrocnemius muscle in DM group (357.49±72.68 vs 221.26±92.41, P<0.01). There were no significant dif?ferences in MCV and CMAP of the sciatic nerve between DM group and control group. The electron microscope observation showed that part of nerve fibers were normal, the myelin focal plate layer was loose and separated, axonal atrophy, the axonal membrane and myelin sheath inner layer was separated with big gap. At the 12th week, MUNE of gastrocnemius muscle (127.87±19.80 vs 366.85±51.25), sciatic nerve MCV [(35.06±4.43) m/s vs (50.47±6.07) m/s] and CMAP [(2.91±1.37) mV vs (5.98±2.14) mV] were significantly decreased in DM group than those of control group (P<0.01). The electron microscopy observation showed severely damaged myelin flex and axonal squeeze. Conclusion MUNE is much earlier in detecting ear?ly motor nerve dysfunction in DM than conventional motor nerve conduction test.

Axon Count and Sympathetic Skin Responses in Lumbosacral Radiculopathy

BACKGROUND AND PURPOSE: Electrodiagnostic studies can be used to confirm the diagnosis of lumbosacral radiculopathies, but more sensitive diagnostic methods are often needed to measure the ensuing motor neuronal loss and sympathetic failure. METHODS: Twenty-six patients with lumbar radiculopathy and 30 controls were investigated using nerve conduction studies, motor unit number estimation (MUNE), testing of the sympathetic skin response (SSR), quantitative electromyography (QEMG), and magnetic resonance myelography (MRM). RESULTS: Using QEMG as the gold standard, the sensitivity and specificity of MUNE for the abductor hallucis longus muscle were 71.4% and 70%, respectively. While they were 75% and 68.8%, respectively, when used MRM as gold standard. The sensitivity and specificity of MUNE for the extensor digitorum brevis muscle were 100% and 84.1%, respectively, when the peroneal motor amplitude as the gold standard. The SSR latency was slightly longer in the patients than in the controls. CONCLUSIONS: MUNE is a simple and sensitive test for evaluating autonomic function and for diagnosing lumbosacral radiculopathy in patients. MUNE could be used routinely as a guide for the rehabilitation of patients with radiculopathies. SSR measurements may reveal subtle sympathetic abnormalities in patients with lumbosacral radiculopathy.

Ubicación de la zona de inervación del músculo flexor corto del pulgar en individuos sanos de ambos sexos / Flexor pollicis brevis muscle innervation zone location in healthy individuals of both sexes

El músculo flexor corto del pulgar (FCP) se localiza en la eminencia tenar y tiene un importante rol en las funciones del dedo pulgar. Existen escasos antecedentes acerca de la distribución de las zonas de inervación (ZI) de este músculo y las posibles diferencias entre individuos de diferente sexo. El conocimiento de la localización de las ZI del FCP podría ser de ayuda en el tratamiento de la mano espástica, sirviendo para definir el sitio de inyección de la toxina botulínica. El objetivo de esta investigación fue describir las ubicaciones de las ZI del FCP usando electromiografía de superficie, y hacer una comparación entre individuos de sexo masculino y femenino. Treinta jóvenes voluntarios sanos, participaron en este estudio (15 hombres: 21.5 +/- 2.6 años, 70.7 +/- 7.2 kg y 175.0 +/- 5.5 cm. 15 Mujeres: 19.9 +/- 1.4 años, 57.9 +/- 11.1 kg y 161.9 +/- 6.6 cm). Las ZI fueron identificadas mediante la grabación de los potenciales de acción de las unidades motoras del FCP, usando un arreglo de dieciséis electrodos de superficie. Los potenciales fueron grabados durante contracciones isométricas al 10 por ciento de la contracción voluntaria máxima. Las localizaciones de las ZI fueron expresadas en forma absoluta y relativa en relación a un sistema de referencia construido en la palma de la mano, en base a referencias anatómicas. No existieron diferencias significativas en las ubicaciones de las ZI entre los participantes de sexo masculino y femenino de la muestra evaluada. Para el grupo de participantes en este estudio, las ZI del FCP se encontraron al 41.9 por ciento de la distancia comprendida entre el extremo palpable más distal y medial de la interlínea articular metacarpofalángica del pulgar y la línea que nace en el vértice palpable del extremo proximal de la primera falange del tercer dedo pasado por el pliegue longitudinal radial.

The flexor pollicis brevis (FPB) is a muscle of the thenar eminence that plays an important role in thumb function. There is data about its innervation zone (IZ) distribution and sex differences. Knowing the location of the ZI of FPB could be helpful in treating spastic hand, serving to define the site of injection of the botulinum toxin. The aim of this study was to describe the IZ location in the FPB using surface electromyography (sEMG), and also make a comparison between male and female subjects. Thirty young healthy volunteers participated in this study (15 males: 21.5 +/- 2.6 years, 70.7 +/- 7.2 kg y 175.0 +/- 5.5cm. 15 Females: 19.9 +/- 1.4 years, 57.9 +/- 11.1 kg y 161.9 +/- 6.6 cm). The IZ was identified by recording the action potentials of the FPB motor units, using a sixteen-electrode array. The action potentials were recorded during isometric contractions at 10 percent of maximum voluntary contraction. The location of the IZ was expressed as absolute and relative values in relation to a reference system constructed in the palm of the hand, based on anatomic references. There were not significant differences in the location of the IZ between male and female subjects. Of all the subjects, the IZ of the FPB was found at the 41.9 percent of the distance between the most distal and medial palpable extreme of the metacarpophalangeal joint line of the thumb and the line which rises at the palpable apex of the proximal side of the first phalanx of the third finger passing through the radial longitudinal fold.

Sarcopenia, exercise and muscle reconstruction / 中国组织工程研究

BACKGROUND:Sarcopenia is the muscle loss in the elderly with aging, and it is closely related to the degradation of muscle function in the elderly. The research on the mechanism of sarcopenia as wel as effect of movement intervention is developed. OBJECTIVE:To summary the mechanisms of sarcopenia cel level as wel as the effect of movement intervention. METHODS:A computer-based retrieval was conducted on CNKI database and PubMed database for literatures on sarcopenia and elderly resistance training from January 2000 to December 2012. The key words were “sarcopenia, muscle, resistance training, aging, protein metabolism”. The literatures on sarcopenia, protein metabolism and resistance training were included, and the obsolete and repetitive literatures and the literatures lack of credibility were excluded. Final y, 58 literatures were included for analysis. RESULTS AND CONCLUSION:Resistance training can inhibit sarcopenia to a certain extent, so that to increase muscle mass in the elderly and promote the recombinant of motor units. But the recombinant is limited to the mutual conversion between the type Ⅱa and Ⅱb fibers. Resistance training combined with protein supplement can effectively promote elderly muscle reconstruction;the elderly muscle anabolic response confrontation reaction after resistance training is slower than young people, but the inflammatory response after training is stronger than younger people. However, Omega-3 has a good effect on the elimination of such inflammatory response.

Effect of recruitment of new MUs on mechanomyographic signal during prolonged isometric constant contractions at low level / 体力科学

The present study focused on the effect of the newly motor unit (MU) recruitment on mechanomyographic signal (MMG) by the analysis on motor unit mechanical signal (MUMS) during prolonged isometric constant contraction (PICC) at low torque levels of the knee extension. The mechanical and myoelectric signals (MES) from m. vastus medialis or lateralis were recorded by condenser microphone and disc electrode, respectively. In order to recruit the objective MU during the PICC, the target torque set at several levels below the recruitment threshold torque of the MU (≦ 7.4 %MVC). 1) iMMG and iMES sustained constant for initial several minutes and then increased during the PICC. 2) MUMS superimposed on MMG from back ground MUs activities and iMUMS increased significantly at the timing of MU recruitment. Subsequent iMUMS decreased according to the decrement of MUMS amplitude depend on the discharge trend of the MU. 3) Amplitude of MUMS (MS-V_positive) showed different trend depended the recruitment timing during PICC. At the iMMG constant phase, MS-V_positive sustained constant followed by the increment similar to iMMG trend. In contrast, at iMMG increment phase, MS-V_positive showed increment trend without the constant phase. The present results suggested that the newly MU recruitment increase the iMMG during the PICC. IMMG increment at later period of the PICC could interpret from the MU recruitment and MS-V_positive increment. It is necessary to investigate the factors to increase the MS-V_positive from the muscle and muscle fibers conditions.

Impact of index finger force on motor unit recruitment pattern in flexor digitorum superficialis / 医用生物力学

Objective To detect the recruitment pattern of motor unit in human flexor digitorum superficialis (FDS) at different force levels produced by the index finger. Methods Eight subjects were recruited to produce a certain force level with the index finger to match the ordered force level (20%, 40%, 60% maximum voluntary contraction). During the force tracking task, the multi-channel surface electromyography (sEMG) signals were recorded on FDS using 8×1 (row×column) electrode-array. The motor unit action potential (MUAP) information was extracted by Fast Independent Component Analysis (FastICA), and then the correlation between MUAP pattern and force level was analyzed. Results Four different types of MUAP were extracted successfully by FastICA from original sEMG signals and the total number of MUAP showed an increasing trend with the force level increasing. At different force levels, the proportion of different types of MUAP was different, showing different trends with change of the force level. ConclusionsAt different levels of the finger force, the recruitment pattern of motor unit in FDS will be changed so as to produce the force accordingly.

Biceps Brachii Muscle Innervation Zone Location in Healthy Subjects Using High-Density Surface Electromyography / Ubicación de la Zona de Inervación del Músculo Bíceps Braquial en Sujetos Sanos Mediante Electromiografía de Superficie de Alta Densidad

Among the sequelae of central nervous system injury is spasticity which is difficult to manage in rehabilitation. Current treatments consider the administration of the botulinum toxin. However, results have proved highly variable in terms of effectiveness, attributable to the distance between the injection site and the innervations-zone (IZ). High Density sEMG (HDsEMG) has been used to gather information about muscle physiology and for location of the IZ. The aim of this study was to characterize the IZ of the biceps brachii muscle in healthy subjects during isometric contraction. We assessed the biceps brachii muscle of twenty healthy subjects (n=20) using a 64 surface electrodes matrix. The average location of the IZ was 34 percent distal to the line between the cubital fossa and the anterior acromion.

Entre las secuelas de lesiones del Sistema Nervioso Central se encuentra la espasticidad, la cual es de difícil manejo terapéutico. Los tratamientos actuales de la espasticidad consideran la administración de la toxina botulínica. Sin embargo, los resultados de su aplicación han sido muy variables en términos de eficacia, atribuible a las distintas distancias entre el lugar de inyección y la zona de inervación (ZI). La EMG de alta densidad se ha utilizado para recolectar información acerca de la fisiología muscular y para localizar la ZI. El objetivo de este estudio fue describir la ubicación de la ZI del músculo bíceps braquial en sujetos jóvenes sanos, durante una contracción isométrica. Evaluamos el músculo bíceps braquial en 20 sujetos sanos usando una matriz de 64 electrodos. El promedio de localización de la ZI fue de 34 por ciento en el sentido distal de la línea trazada entre la fosa cubital y el acromion anterior.

RELATIONSHIP BETWEEN INTER-SPIKE INTERVAL AND AMPLITUDE OF MECHANOMYOGRAPHIC SIGNAL FROM SINGLE MOTOR UNITS DURING VOLUNTARY MUSCLE CONTRACTION / 体力科学

To investigate factors that increase the mechanomyographic (MMG) signal during voluntary prolonged muscle contraction at relatively low tension levels, the MMG signal from the motor unit (MU mechanical signal: MUMS) was analyzed. In the present study, the author focused on the interval dependency of MUMS amplitude as one of the factors to increase MMG. From the m. vastus medialis or m. vastus lateralis, MUAP and myoelectrical signal (MES) were recorded by Ag/AgCl disc electrode and MMG and MUMS were respectively recorded by condenser microphone during various types of muscle contractions; brief isometric constant contraction (BICC), prolonged isometric constant contraction (PICC) and prolonged isometric contraction under constant MU firing interval (PIC-CFI).The amplitude of positive phase in MUMS (MS-V_positive) increased proportionally with the firing interval of the MU in BICC. The firing interval of MU showed an initial elongation, followed by shortening during PICC. During PICC and PIC-CFI, MS-V_positive sustained in an initial part of the contraction and then abruptly increased. There was no meaningful relationship between the firing interval and MS-V_positive during PICC and PIC-CFI. However, the increment ratio of the MS-V_positive in PIC-CFI was smaller than that in PICC.The present results on MS-V_positive suggested that the increment of MMG during PICC did not depend on the firing interval change in the activated MUs. Based on findings with different increment ratios in MS-V_positive between PICC and PIC-CFI, it is suggested that the hysteresis of muscle contraction is one of the factors causing an increase in MUMS and MMG.

Comparison of Motor Unit Number Estimates and Conventional Electromyogram in the Detection of Neuromuscular Diseases / 中国康复理论与实践

@#: ObjectiveTo compare the clinical significance of motor unit number estimates (MUNE) and conventional electromyogram (EMG) in the evaluation of neuromuscular disorders. MethodsUnder the model of MUNE or quantity of motor unit potential (QMUP), 53 patients with various neurogenic disorders were tested with EMG at extensor digitorum brevis, thenar, or hypothenar eminence. ResultsFor 8 patients with amyotrophic lateralizing sclerosis, large and long-duration polyphasic potentials were detected in needle electrode EMG tests, and the motor unit numbers reduced. For 45 patients with peripheral neuropathies, few distinctive features could not be detected by needle electrode EMG, but motor unit numbers reduced in 2 patients; spontaneous activities were the only abnormality in the other 2 patients, and there were no obviously abnormal changes in the configuration and size of motor unit potentials and in motor unit numbers; EMG tests revealed neurogenic features and motor unit numbers significantly reduced in the remaining 41 patients. ConclusionConventional EMG and MUNE can work for the diagnosis of neuromuscular disorders, and do better in combination.

Motor Unit Number Estimation in Evaluating Disease Progression in Patients with Amyotrophic Lateral Sclerosis

We investigated the availability of motor unit number estimation (MUNE) as a quantitative method to assess the severity and clinical progression of amyotrophic lateral sclerosis (ALS). The 143 ALS patients were evaluated by statistical MUNE and the revised amyotrophic lateral sclerosis functional rating scale (ALSFRS-R). By using mean values of MUNE according to disease duration, regression equation between mean MUNE and disease duration was presented as a formula. The individual MUNE ratio was calculated by dividing individual MUNE value by mean MUNE value. All patients were classified into 2 groups (MUNE ratio or =1) according to the MUNE ratio. Comparison between the 2 groups revealed that the patients in MUNE ratio or =1 group were respectively assigned to rapid progression or slow progression. We recommended informative mean values of MUNE and best regression equation in ALS patients according to disease duration. These values allow us to evaluate the severity and rapidity of progression in ALS.

MOTOR UNIT MECHANOMYOGRAPHIC SIGNAL AND SYNCHRONIZED ACTIVITY IN MOTOR UNITS DURING VOLUNTARY MUSCLE CONTRACTIONS / 体力科学

The aim of the present study was to investigate, by analysis of motor unit action potential (MUAP) and motor unit mechanomyogram (MUMS) wave-forms, whether the synchronized activity of motor units (MUs) is a factor in increasing the integrated value of a mechanomyogram during muscle contraction at relatively low tension levels. MUAP and MUMS of m. vastus medialis were recorded by Ag/AgCl disc electrode ( 5mmφ) and condenser microphone ( 10mmφ), respectively, during muscle contractions, brief isometric constant contractions (BICC) and prolonged isometric constant contraction (PICC) at the target torques from just above the decruitment threshold torque of the objective MU to 20% of maximal voluntary contraction (MVC). The degree of synchronization of MUs, defined from the amplitude of late positive deflection (VLPD), could be seen in MUAP wave-forms.The amplitude of the positive phase in MUMS (MS-V_positive) had no relationship with the increase of V_LPD in BICC condition. During PICC, MS-V_positive and V_LPD increased with time. Applying linear regression analysis on the relation between V_LPD and MS-V_positive, except for data at 20%MVC, there was significant correlation. However, the scale of the time increments, between V_LPD and MS-V_positive, were different comparing exponential and logarithmic figures, respectively. Therefore, in the present experiment, the meaningful relationship between the two parameters could not be introduced. It is necessary to further investigate the relationship between the two parameters including the firing frequency of MU, intramuscular pressure and extent of recording area of both sensors.

A Study on the Decomposition of Surface EMG Signals Based on Second Order Non-stationary Source Separation / 航天医学与医学工程

Objective To investigate the decomposition method of surface EMG(sEMG)signals based on Blind Source Separation and to detect the the motor unit action potential(MUAP)information.Methods Utilizing the sEMG signals recorded at low muscle contraction force(10% MVC),the methods of second order non-stationary source separation(SEONS)and FastICA were explored to analyze the sEMG signals decomposition.Results The experiment results showed that the MUAP information could be acquired by spike detection and pattern recognition after the decomposition of recorded sEMG signals using the proposed algorithm and FastICA method,but a little difference occurred due to the complexity of sEMG signals.Conclusion The non-stationary characteristic of sEMG signals is considered by the SEONS algorithm,and the proposed method can be applied in the sEMG signals decomposition.

Motor Unit Action Potentials of the Rectus Abdominis Muscle according to Changes of Abdominal Pressure

OBJECTIVE: In current urodynamic studies, rectal catheters can cause erroneous result affecting detrusor pressure, and the catheter itself is not comfortable to the patients. To reduce these problems we investigated the relationship between the motor unit action potentials (MUAP) of rectus abdominis muscle and the abdominal pressure measured by rectal catheter. METHOD: Healthy seven men and three women volunteers (mean age: 49 years) with no neurological abnormality were enrolled. Possible maximal abdominal pressure (Pmax) was attained by Valsalva maneuver for 5 seconds. The MUAPs of the rectus abdominis muscle were recorded with surface electrodes for analysis. These recordings were done on 100, 80, 60, 40, and 20% of Pmax. The parameters of MUAP such as mean frequency, median frequency, turns, mean amplitude, and RMS (root mean square) were measured. RESULTS: Turns, mean amplitude, and RMS were increased in a proportion to the increment of abdominal pressure in all subjects(R=0.840, 0.879, and 0.984, respectively). CONCLUSION: These findings suggested that the surface MUAP of rectus abdominis muscle might be used indirectly for more convenient measurement of the abdominal pressure.