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

Continuous Motion Estimation of Elbow Joint Based on Multi-Modal Information Fusion / 医用生物力学

Objective Aiming at the problems of lacking initiative in upper limb rehabilitation training equipment, single training mode, and low active participation of patients, an upper limb continuous motion estimation algorithm model based on multi-modal information fusion was proposed, so to realize accurate estimation of elbow joint torque. Methods Firstly, the surface electromyography (sEMG) signal and posture signal of participants were collected at four angular velocities, and the time domain characteristics of the signal were extracted. The principal component analysis was adopted to multi-feature fusion. The back propagation neural network (BPNN) was optimized through the additional momentum and the adaptive learning rate method. The particle swarm optimization (PSO) algorithm was used to optimize the neural network and a continuous motion estimation model based on PSO-BPNN was constructed. Finally, the joint torque calculated by the second type of Lagrangian equation was used as the accurate value to train the model. The performance of the model was compared with the traditional BP neural network model. Results The root mean square error (RMSE) of the traditional BP neural network model was 558.9 N·m, and the R2 coefficient was 77.19%, Whereas the RMSE and the R2 coefficient of the optimized model were 113.6 mN·m and 99.12%, respectively.Thereby, the accuracy of torque estimation was improved apparently. Conclusions The method for continuous motion estimation of the elbow joint proposed in this study can estimate the motion intention accurately, and provide a practical scheme for the active control of upper exoskeleton rehabilitation robot.

Kinematic and Dynamic Study on Traditional Chinese Cervical Manipulation / 医用生物力学

Objective To simultaneously collect and analyze the kinematic and dynamic parameters for two techniques of traditional Chinese cervical manipulation ( TCCM), and quantitatively describe its biomechanical characteristics. Methods A senior practitioner completed the TCCM (positioning and directional rotation pulling, lateral flexion, respectively) on 10 healthy subjects, and the fluorescent marker balls were pasted on the operator to capture manipulation movements. The dynamic parameters and the surface electromyography ( sEMG) signals were collected by pressure-sensitive gloves and wireless sEMG acquisition system. Results The upper arm muscle was the main force muscle during TCCM, and biceps brachii had the highest contribution rate. The range of motion (ROM), speed, pulling force, and time during cervical spine positioning and directional rotation pulling were all greater than those during cervical spine lateral flexion. The integrate electromyography ( iEMG) and root mean square (RMS) for each muscle of the operator during cervical spine positioning and directional rotation pulling were higher than those during cervical spine lateral flexion. Conclusions The overall ROM, three-dimensional (3D) motion angle, load intensity and time during CCTM have the characteristics of high speed, low amplitude and strong force, reflecting the biomechanical characteristics of ‘ cunjin ’ ( one-inch punch ) in traditional Chinese medicine. This study provides references for further standardizing manual teaching and training and improving clinical safety.

Assessment of Postoperative Surface Electromyography and Joint Angle in Children with Spastic Cerebral Palsy / 医用生物力学

Objective To analyze and assess the postoperative motor function in children with spastic cerebral palsy (SCP) by surface electromyography (sEMG) and joint angle. Methods Sixteen children with SCP were involved in this study. The sEMG of rectus femoris, biceps femoris, semitendinosus, tibialis anterior, lateral gastrocnemius and medial gastrocnemius muscles and joint angles of the hip, knee and ankle during straight walking were collected preoperatively and postoperatively. In every gait phase, the mean values of joint angles, root mean square and integrated electromyography of sEMG were calculated, to evaluate muscle strength and muscular tension quantitatively. Results The muscle tension of lower limbs was significantly decreased (P<0.05). The muscle strength of rectus femoris and biceps femoris was decreased in the swing phase. At the midswing and terminal swing phase, the strength of tibialis anterior increased significantly (P<0.05). The flexion angle of hip and knee decreased significantly (P<0.05). The dorsiflexion angle of ankle increased significantly (P<0.05), and the varus angle decreased significantly (P<0.05). Conclusions After operation, the crouching gait and clubfoot were improved positively. Therefore, the motor function of children was improved. Combining sEMG and joint angle can evaluate the muscle function of patients quantitatively, and it also can provide references for clinical diagnosis.

Comparison of Muscle Activation and Co-Contraction Patterns for Trunk Muscles During Four-Point Hand-Knee and Hand-Foot Kneeling Positions / 医用生物力学

Objective To analyze the similarities and differences between four-point hand-knee position and hand-foot kneeling positions in trunk muscle activation and co-contraction, explore the possibility of hand-foot kneeling position as core stabilization exercises, so as to provide suggestions for actual training.Methods Nineteen healthy volunteers randomly performed exercises of four-point hand-knee position (4 motions) and hand-foot kneeling position (3 motions), while surface electromyography (sEMG) signals were collected from bilateral rectus abdominis, external oblique, erector spine, and multifidus muscles. The average sEMG and muscle co-contraction index (CCI) based on the sEMG signals were analyzed and compared.Results Significant differences were found in the sEMG and CCI within and between the two positions. Under four-point hand-knee position with the right hand and left leg lifting, the activation of all muscles was higher than that in the starting position. In four-point hand-knee position with the left leg lifting, the activation of ipsilateral multifidus muscle was significantly higher than that in hand-foot kneeling position. The activation degree of external oblique muscle and rectus abdominis was higher in hand-foot kneeling position with right hand lifting. A total of 28 muscle matching methods were obtained by pair-to-pair matching of 8 muscles. The starting posture in four-point hand-knee position fluctuated the least, indicating that the spine was the most stable, while the index of other exercises fluctuated in a larger range.Conclusions The possibility of hand-foot kneeling position as core stabilization exercises was proved from two aspects, namely, muscle activation and CCI. The hand-foot kneeling position and four-point hand-knee position can be used for strengthening abdominal muscles and back muscles, respectively. The four-point hand-knee position with contralateral upper and lower limbs lift is a more advanced exercise for trunk muscles, but sports injuries should be avoided.

Development of an Anterior Foot Drop Ankle Foot Orthosis with Adjustable Stiffness / 医用生物力学

Objective For patients with foot drop gait, to design a kind of anterior ankle foot orthosis (AFO) with adjustable stiffness, so as to restore natural gait of the ankle by limiting the patients’ unusual plantar flexion to the optimum extent. Methods The minimum orthodontic moment of 10 foot drop male patients was measured by self-made experimental equipment, which could be used to select optimum material modulus of the AFO. The relationship between elastic modulus and different filling structures and filling ratio parameters was studied by tensile test. A typical patient with foot drop was selected, and the anterior AFO fitting the shape of patient’s foot was quickly made by three-dimensional (3D) printing with foot geometric data and specific filling material, filling structure and filling rate. The kinematics and surface electromyography (sEMG) of plantar flexors were tested under barefoot and wearing two kinds of AFOs, so as to verify the effect of the AFO on plantar flexion. The effectiveness of the limitation and the degree of preservation of ankle valgus and plantar flexion were discussed. Results The minimum corrective torque required for 10 male patients with foot drop was 2.16 N·m. Compared with the rigid AFO, the range of motion (ROM) of plantar flexion and valgus increased by 67.8% and 88.6% respectively with the flexible AFO. The activation of the muscles responsible for plantar flexion (soleus, medial head of gastrocnemius and lateral head of gastrocnemius) also decreased by 38.3%, 46.6% and 55.8%. Conclusions This AFO with adjustable stiffness can be used for orthosis customization of patients with foot drop, providing more effective and long-term orthosis function and potential.

Therapeutic effect of nape cluster acupuncture combined with swallowing function training on post-stroke dysphagia / 中国针灸

OBJECTIVE@#To observe the effect on swallowing function in patients with post-stroke dysphagia treated with nape cluster acupuncture and the immediate effect of acupuncture at Fengchi (GB 20).@*METHODS@#A total of 60 patients with post-stroke dysphagia were randomized into an observation group and a control group, 30 cases in each one.On the basis of conventional western medication treatment, swallowing function training was applied in the control group, once a day.On the base of the treatment as the control group, nape cluster acupuncture was applied at Fengchi (GB 20), Tianzhu (BL 10), Wangu (GB 12), Lianquan (CV 23), Panglianquan (Extra), Jinjin (EX-HN 12) and Yuye (EX-HN 13) in the observation group, once a day. Additionally, pricking blood was applied at Jinjin (EX-HN 12) and Yuye (EX-HN 13), 2 times a week. The treatment was given 30 min each time, a week as one course and 4 courses were required. Before and after treatment, the standardized swallowing assessment (SSA) score and video fluoroscopic swallowing study (VFSS) score were compared in the two groups. The ultrasonic diagnostic device of swallowing and surface electromyography were used to observe the immediate effect on swallowing related muscles of acupuncture at Fengchi (GB 20).@*RESULTS@#Compared before treatment, the SSA scores were reduced after treatment in the two groups (<0.05), and the change of the observation group was larger than the control group (<0.05). Compared before treatment, the VFSS scores were increased after treatment in the two groups (<0.05), and the change of the observation group was larger than the control group (<0.05). Acupuncture at Fengchi (GB 20) immediately increased the amplitude of submental muscles and infrahyoid muscles in the observation group (<0.05), the geniohyoid muscle movement time was reduced and geniohyoid muscle displacement was increased (<0.05).@*CONCLUSION@#On the base of the routine treatment, nape cluster acupuncture could improve swallowing function in patients with post-stroke dysphagia. Acupuncture at Fengchi (GB 20) could immediately affect swallowing related muscles, improve muscle amplitude and reduce swallowing time.

Research Progress and Joint Evaluation on Center of Rotation for Lumbar Vertebrae / 医用生物力学

In recent years, with the growth of social development, the incidence of lumbar vertebrae diseases has increased year by year, and many surgical methods have been developed. These treatment methods mark the accumulation of surgical experience and the development of medical technology. However, a new issue appears, i.e. how to evaluate the degree of lumbar disease and postoperative rehabilitation. There is an urgent need to establish a quantitative index of preoperative examination and postoperative rehabilitation criteria for lumbar disease from both doctors’ and patients’ perspectives. The current studies show that the measurement of the center of rotation (COR) for lumbar vertebrae and surface electromyography (sEMG) can reduce the error in the evaluation of clinical curative effect for treating lumbar disease and can be applied widely. This review summarizes the relationship between COR and lumbar disease, as well as the role of COR and sEMG joint evaluation in clinical operation and postoperative rehabilitation.

Fall Risk Analysis of Elderly People with Different Load Distributions during Obstacle Crossing Based on Surface Electromyography / 医用生物力学

Objective To study the factors leading to the increased risk of falls when the elderly cross obstacles with different load distributions in their hands, and to explore the gait strategies to prevent falls for elderly people with different load distributions during obstacle crossing. Methods Twelve young healthy (control group) and 12 elderly healthy participants performed walking tasks with or without obstacle crossing at their daily speed under different load distributions. Surface electromyography (sEMG) signals were collected from both sides of the lateral femoris, rectus femoris and medial femoris. Then the average sEMG was analyzed and compared. The numbers of contact incident during obstacle touching were also recorded. Results Age, weight carrying and obstacle all had significant influences on the activity level of lower limb muscles in elderly people. A total of 9 contact incidents occurred in 1 152 obstacle crossing tests. In addition, the contribution of right vastus medialis muscle was the greatest in the elderly and young adults when they completed the weight carrying and obstacle crossing tasks. Conclusions The elderly people had the lowest risk of falling down by taking advantage of the dominant side of the leg to take the lead in obstacle crossing under the uniform distributions of load. The research findings provide references for systematic assessment of fall risk in the elderly and have certain guiding significance for lower limb exercise or rehabilitation training in the elderly.

Efficacy of acupuncture for spastic cerebral palsy in infancy stage / 中国针灸

OBJECTIVE@#To explore the therapeutic effect of acupuncture for spastic cerebral palsy in infancy stage.@*METHODS@#A total of 62 children with spastic cerebral palsy were randomized into an observation group and a control group, 31 cases in each one. Both groups were given comprehensive rehabilitation therapy (sport therapy, electronic biofeedback therapy, speech cognitive training, massage therapy). On the basis of comprehensive rehabilitation therapy, the acupuncture group was treated with acupuncture at Baihui (GV 20), Sishencong (EX-HN1), motor area, Jiaji (EX-B 2), Weizhong (BL 40), Xuanzhong (GB 39), Zusanli (ST 36) and Hegu (LI 4), etc, the needles were retained for 15-20 min each time, once a day, 5 days a week, 45 days as a course with 10 days interval, a total of 3 courses were required. The Gesell development scale adaptive DQ scores, gross motor function measure (GMFM88) and muscular tension of adductor and gastrocnemius muscle were compared before and after treatment in the two groups.@*RESULTS@#The Gesell development scale adaptive DQ score after treatment in the observation group was increased (0.05), the change of the observation group was larger than the control group (0.05).@*CONCLUSION@#Acupuncture combined with comprehensive rehabilitation therapy can improve cognitive function, spasticity and motor function of children with spastic cerebral palsy.

Sistema de biofeedback para rehabilitación de marcha asistida por un exoesqueleto / Biofeedback System for Exoskeletqn Assisted Gait Rehabilitation / Sistema de biofeedback para reabilitação de marcha assistida por um exoesqueleto

Resumen Los robots proporcionan nuevas formas de terapia para pacientes con desórdenes neurológicos. Las terapias de marcha asistidas con exoesqueletos pueden incrementar la duración y la intensidad de los entrenamientos para los pacientes y reducir el esfuerzo físico del terapeuta. Sin embargo, el uso de estos dispositivos para el entrenamiento de la marcha limita la interacción física entre el terapeuta y el paciente, en comparación con la terapia manual. Una apropiada realimentación de las funciones corporales y biomecánicas en la interacción con el sistema robótico facilita la evaluación del desempeño del paciente, motivándolo en el reaprendizaje de la marcha con resultados superiores. Este artículo presenta el diseño de una interfaz de usuario para un exoesqueleto de miembros inferiores para asistencia en la marcha y en terapias de rehabilitación. Se consideraron aspectos técnicos y clínicos para proporcionar ventajas del exoesqueleto durante las terapias, estableciendo una herramienta de apoyo para la configuración, monitoreo y registro de los parámetros involucrados. Se propuso un esquema de realimentación sensorial para el paciente acerca de la actividad muscular, la presión ejercida en diferentes puntos de los pies y algunas variables biomecánicas. Finalmente, se valida la herramienta con sujetos sanos por medio de un test de usabilidad propuesto.

Abstract The inclusion of robots in rehabilitation allow advantages for generate newer therapies in neurologic disorder patients. Assistive gait therapies using robots, like exoskeletons, allow increase the time and intensity training for patients while the strenuous labor of therapist is reduced. However, the physic interaction between therapist and patient in training with robots is limited, in relation to the traditional manual therapy. An appropriated feedback of biological and biomechanics functions in the robot interaction during training provides an easier performance evaluation of the patient for the therapist. Further, biofeedback gives a motivation to the patient and encourages him for gait relearning with higher effects than conventional. This paper presents a user interface design for a lower limb exoskeleton for human gait assistance in rehabilitation. Clinical and technical criteria for increasing the advantages of the exoskeleton in therapy were considered. A biofeedback scheme about muscle activity, plantar pressure and some biomechanics variables, for the patient is proposed. Finally, a validation for this tool with healthy subjects by a usability test was carried out.

Resumo A inclusão de robôs na reabilitação fornecem vantagens que promovem novas formas de terapia em pacientes com desordens neurológicas. Terapias de marcha assistidas por exoesqueletos permitem o aumento da duração e da intensidade dos exercícios com os pacientes, reduzindo o esforço físico dos terapeutas. Não entanto, o uso desses dispositivos para o treino da marcha limita a interação física entre o terapeuta e paciente, em comparação com a terapia manual. Uma apropriada realimentação das funções corporais e biomecânicas na interação com o sistema robótico facilita a avaliação do progresso do paciente, motiva e incentiva ao paciente na reaprendizagem da marcha gerando efeitos superiores aos convencionais. Neste artigo apresenta-se o desenho de uma interface de usuário para um exoesqueleto de membros inferiores para assistência na marcha e nas terapias de reabilitação. São considerados aspectos técnicos e clínicos para fornecer maiores vantagens do exoesqueleto durante as terapias, estabelecendo uma ferramenta de suporte para configuração, monitoramento e registro dos parâmetros envolvidos. Foi proposto um sistema de realimentação sensorial para o paciente sobre a atividade muscular, a pressão em diferentes pontos dos pés e algumas variáveis biomecânicas. Finalmente, é apresentada a ferramenta de validação para indivíduos saudáveis utilizando um teste de usabilidade proposto.

Plantar Pressure and Surface EMG Parameters During Stair Walking / 医用生物力学

Objective To explore the plantar pressure and surface electromyography (sEMG) parameters during human stair walking, so as to provide theoretical support for foot structure design of dynamic walker, selection of power element and distribution of installation location. Methods Ten healthy young males were recruited to perform stair walking trials, respectively. The motion capture system, plantar pressure system and surface myoelectricity acquisition system were used to collect plantar peak pressure, trajectory of COP(center of pressure) and sEMG parameters of lower limb muscles at the same time. Results Compared with level walking, the percentage of stance time in the whole gait cycle increased during stair walking. The peak pressure of forefoot area increased during stair ascent, while the peak pressure of toe area decreased during stair descent. During stair walking, rectus femoris, biceps femoris, medialis and lateralis gastrocnemius played a main role in maintaining the stability of human body. Conclusions The plantar pressure distribution should be fully considered for foot structure design of dynamic walker and the function of main muscles should be considered for selection of power element and distribution of installation location.

Effects of intradermal needling on core muscle stability in children with cerebral palsy: a clinical comparative study / 中国针灸

<p><b>OBJECTIVE</b>To observe the effects of rehabilitation training (RT) combined with intradermal needling, RT combined with acupuncture and RT alone on core muscle stability in children with cerebral palsy, and to explore the superior therapy to improve core muscle stability in children with cerebral palsy.</p><p><b>METHODS</b>A total of 120 children with cerebral palsy aged from 2 to 4 years old were randomly divided into a RT and intradermal needling group (group A), a RT and acupuncture group (group B) and a RT group (group C), 40 cases in each one. The patients in the group C were treated with kinesitherapy and core muscle stability training, once a day. Along with identical RT of group C, the patients in the group B were treated with acupuncture (once a day), while the patients in the group A were treated with intradermal needling at Yaoyangguan (GV 3), Mingmen (GV 4), Jiaji (EX-B 2, L-L), and 4-week treatment was taken as one course. The integrated electromyography (iEMG) of surface electromyography, root mean square (RMS) and mean power frequency (MPF) of erector spinae muscles, Berg balance scale as well as B area (siting), C area (climbing and kneeling), D area (standing) and E area (walking, running and jumping) of gross motor function measure (GMFM) were compared before and after 3-course treatment.</p><p><b>RESULTS</b>① Compared before treatment, the iEMG and RMS of erector spinae muscles in the group A and group B as well as MPF in the group A were all increased after treatment (all <0.05); after treatment, all the electromyography indexes in the group A were higher than those in the group B and group C (all <0.05); the RMS in the group B was higher than that in the group C (<0.05). ② Compared before treatment, the Berg balance scale was all increased after treatment in the three groups (all <0.05), and the scale in the group A was higher those that in the group B and group C (both <0.05). ③ Compared before treatment, the B area and C area of GMFM in the three groups as well as D area in the group A and group B were all improved after treatment (all <0.05); the B area, C area and D area in the group A and group B were higher than those in the group C (all <0.05); the B area and C area in the group A were higher than those in the group B (both <0.05).</p><p><b>CONCLUSION</b>Based on RT, the intradermal needling could better improve core muscle stability and balance-motor ability in children with cerebral palsy, which is superior to regular acupuncture and RT alone.</p>

The Effect Of Grasping The Steering Wheel While Positioning The Shoulder Closer To The Body

@#Discomfort and pain issue at the body part are common complaints reported by car drivers. It is due to driving task require physical demands and need to maintain and adapt several postures in a constrained space while controlling the car. Hence, this study aims to determine the pattern of shoulder activation muscle consisting of the Trapezius muscle in two different driving posture. Respondents were required to grasp the steering wheel at 8 and 4 hand position. The Surface Electromyography was used to get the reading for left muscle’s Trapezius Descendent (TD) at two different positions; i) closest distant from steering wheel and ii) far distant from the steering wheel. Then, Temporal Analysis was used to evaluate the pattern of the driving action. From the experiment, it shows the different value of muscle activation occurred while driving according to turning action. The far seated position depicted greater activation on driving action compared to the closer seated to the steering wheel. In conclusion, the driving posture effects the activation of shoulder and arm’s muscles as early as after 20 seconds of driving activity. Hence, choosing the correct driving posture allowed a comfortable driving environment for the driver.

Deltoid Anterior Contraction In Maneuvering The Steering Wheel

@#While driving, a driver is required to control the steering wheel to change direction. The driver’s muscles of the upper limbs and shoulders are involved in such a task. Therefore, an assessment of the driver’s physiology according to certain condition is necessary to improve driving comfort and safety. This study aims to investigate the driver’s Deltoid Anterior (DA) muscle activity while operating the steering wheel. Eleven test subjects were recruited for an experiment using a car simulator. They were required to remain in the car seat and perform the task of steering the wheel. Surface electromyography (SEMG) was used to record each subject’s muscle contraction while turning the steering wheel to the right and left by several degrees. According to the findings, 45 degrees turning recorded the highest Root mean Square (RMS) value for DA. In addition, DA muscle activation increased with more degrees turning.

Adaptation of a smart walker for stroke individuals: a study on sEMG and accelerometer signals

Abstract Introduction: Stroke is a leading cause of neuromuscular system damages, and researchers have been studying and developing robotic devices to assist affected people. Depending on the damage extension, the gait of these people can be impaired, making devices, such as smart walkers, useful for rehabilitation. The goal of this work is to analyze changes in muscle patterns on the paretic limb during free and walker-assisted gaits in stroke individuals, through accelerometry and surface electromyography (sEMG). Methods The analyzed muscles were vastus medialis, biceps femoris, tibialis anterior and gastrocnemius medialis. The volunteers walked three times on a straight path in free gait and, further, three times again, but now using the smart walker, to help them with the movements. Then, the data from gait pattern and muscle signals collected by sEMG and accelerometers were analyzed and statistical analyses were applied. Results The accelerometry allowed gait phase identification (stance and swing), and sEMG provided information about muscle pattern variations, which were detected in vastus medialis (onset and offset; p = 0.022) and biceps femoris (offset; p = 0.025). Additionally, comparisons between free and walker-assisted gaits showed significant reduction in speed (from 0.45 to 0.30 m/s; p = 0.021) and longer stance phase (from 54.75 to 60.34%; p = 0.008). Conclusions Variations in muscle patterns were detected in vastus medialis and biceps femoris during the experiments, besides user speed reduction and longer stance phase when the walker-assisted gait is compared with the free gait.

Study on Neural Co-activation during Human Upper Limb Muscle Fatigue Based on Surface Electromyography / 中国运动医学杂志

Objectives To observe the co-activation phenomenon during exercise fatigue induced by the proximal muscles on the upper limbs.Methods Sixteen undergraduates not majoring in sports participated in this study,and their left arms were chosen as the observed arms and right arms were selected as the weighted arms.The weighted arm was alternatively in the state of relaxation without any load and fatigue after bending and extending elbow joints to uphold a 5 kg dumbbell.However,the observed arm kept weighing a 4 kg dumbbell with 90 degrees elbow flexion until the muscles were exhausted.The surface electromyography of biceps brachii and triceps brachii of the observed arms was measured using the ME6000.And the integrated surface electromyography (IEMG),root of mean square (RMS),mean power frequency (MPF)and median frequency (MF)were further analyzed.Results The IEMG and RMS of biceps brachii and triceps brachii of the observed arms increased gradually after the exercise began (P＜0.05)regardless of in the relaxed state or in the in the state of weighing a 5 kg dumbbell for the weighted arm,but in the state of weighting a 5 kg dumbbell the IEMG and RMS increased more significantly (P＜0.01),Meanwhile the electrical activities of the triceps brachii as an antagonistic muscle were intensively inhibited.The changes of MPF and MF of biceps brachii in the observed arms were more significant in the state of exercise fatigue than in the relaxed state (P＜0.01),but without such an impact on the triceps brachii.Conclusions The fatigue in one arm can trigger contingent changes in sEMG time domain and frequency domain indexes of its contralateral parallel muscles,suggesting that sEMG changes of upper limb proximal muscles have the co-activation effect.

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.

Electromyographic analysis of riding posture during the bicycling start moment

Abstract Professional cyclists often adopt a competition-start standing posture, which has been shown to improve performance. The biomechanical basis of this is unclear, and might be due to a greater mechanical advantage or increased key muscle activity. Previous observations in steady state cycling showed greater activation of the tibialis anterior, erector spinae, and biceps brachii when adopting a standing vs. seated-riding posture. Little is known regarding the effect of riding posture on activation during a standing start. Eleven cyclists performed standing starts in seated and standing-postures using stationary-cycle and on the track. Electromyography of the gastrocnemius medialis, tibialis anterior, erector spinae, and biceps brachii was recorded during first and subsequent pedal strokes. Results showed that the gastrocnemius medialis did not modify activity. The tibialis anterior, erector spinae, and biceps brachii activity was increased during the standing posture compared to seated, only during the first pedal stroke. These increased activation intensities were accompanied by a corresponding 10% increase in bike speed during the first 5 meters following a standing start in the standing posture compared to the seated one. Adopting a standing posture during a standing start improves performance through greater initial acceleration.

Influence of knee extension in sitting position with hip adduction on surface EMG of quadriceps muscles in patients with patellofemoral pain syndrome / 医用生物力学

Objective To investigate the possible effect of fully knee extension in sitting position with or without hip adduction on quadriceps imbalance in patients with patellofemoral pain syndrome (PFPS) by using surface electromyography (sEMG). Methods sEMG signals of vastus lateralis (VL) and vastus medialis oblique (VMO) muscles from 30 patients with PFPS as PFPS group and 30 healthy subjects as control group were collected, during their fully knee extension in sitting position with or without hip adduction. All the EMG data were then analyzed by extracting time domain indexes, namely, the root mean square (RMS) and integrated EMG (IEMG), to compare the balanced relationship between VL and VMO muscles. Results In PFPS group, there were no significant differences in VL time domain indexes during knee extension in sitting position with or without hip adduction, while statistical differences were found in VMO time domain indexes, and values of RMS and IEMG of VMO were higher under hip adduction, which indicated that the VMO muscle recruitment was strengthened. Conclusions Fully knee extension in sitting position with hip adduction can promote EMG activities of VMO muscles in patients with PFPS, which will help to balance the VL and VMO muscles.