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1

Deep learning and machine learning techniques to improve hand movement classification in myoelectric control system

Rajapriya R., Rajeswari K., Thiruvengadam S. J.

Biocybernetics and Biomedical Engineering

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2021

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Vol. 41, no. 2

554--571

EN

A robust myoelectric control system (MCS) is essential for the design of electromyography (EMG) based human–machine interface (HMI) designs such as prosthetics, exoskeleton, wheelchair and humanoid robots. The functionality of the current pattern recognition (PR) technique in MCS is limited by factors such as variation in the user’s limb position. To overcome the effect of this dynamic variation, an invariant higher order statistics – frequency domain feature set (HOS-FD) is proposed in this paper. EMG data from eight hand movements in five limb positions are considered. When trained with three limb position data, the HOS-FD with three hidden layers deep neural network (DNN) achieved a significantly high classification accuracy of 97.84%±0.22 compared to other classifiers viz., single layer artificial neural network (ANN), linear discriminant analysis (LDA), support vector machine (SVM), k nearest neighbor (kNN), decision tree (DT) and Naive Bayes (NB) classifiers with accuracies of 94.11%±1.63, 95.02%±1.89, 94.63%±2.33, 90.05 ± 4.11, 86.66 ± 4.72 and 78.78%±5.02 respectively. Further, when trained with data from all five limb positions, the proposed feature set with DNN had an accuracy of 99.16%±0.14. The statistical significance of the high classification accuracy obtained using the proposed feature set is also proven using multiple analysis of variance tests (p < 0.001). These results indicate that the proposed method is a promising technique for HMI.

2

Analysis of artefacts in EEG signal registered during anti-G straining maneuvers

Kołodziej Marcin, Kowalczuk Krzysztof Paweł, Majkowski Andrzej, Tarnowski Paweł, Gaździński Stefan, Rak Remigiusz Jan

Przegląd Elektrotechniczny

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2020

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R. 96, nr 1

124--128

EN

An anti-G straining maneuver (AGSM) is an essential element of training pilots of high-maneuver aircrafts. Electroencephalographic signal (EEG) registered during such maneuvers could be used to detect cerebral ischemia. AGSM involves complicated physical tasks, from stretching certain parts of muscles through adequate breathing. This results in the creation of extremely large muscle artefacts, which significantly disrupt the recorded EEG signals. The presented research concerned EEG signals, recorded during individual AGSM phases, inside an overload centrifuge. The largest artefacts in the EEG band (0.5-300Hz) were observed for the electrodes Fp1, F9, FT9 and EMG1 located on cheek. The signal from the Cz and Pz electrodes appeared to be the least disturbed.

PL

Manewr przeciw-przeciążeniowy (AGSM) jest niezbędnym elementem szkolenia pilotów samolotów wysokomanewrowych. Sygnał elektroencefalograficzny (EEG) zarejestrowany podczas tych manewrów mógłby posłużyć do wykrycia niedokrwienia mózgu. Manewr przeciwprzeciążeniowy, obejmuje skomplikowane zadania fizyczne, od napinania pewnych partii mięśni, poprzez odpowiednie oddychanie. Powoduje to powstanie ekstremalnie dużych artefaktów odmięśniowych, które zakłócają, w sposób znaczący, rejestrowane sygnały EEG. Zaprezentowane badania dotyczyły sygnałów EEG zarejestrowanych podczas wykonywania poszczególnych faz AGSM, we wnętrzu wirówki przeciążeniowej. Największe artefakty w paśmie EEG (0.5-300Hz) zaobserwowano dla elektrod Fp1, F9, FT9 oraz EMG1 ulokowanej na policzku. Najmniej zakłócony okazał się sygnał zarejestrowany z elektrod Cz i Pz.

3

Which of the five classical ballet positions is the most demanding for the dancer’s body? An electromyography-based study to determine muscular activity

Gorwa Joanna, Kabaciński Jarosław, Murawa Michał, Fryzowicz Anna

Acta of Bioengineering and Biomechanics

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2020

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Vol. 22, no. 4

3--14

EN

The study aimed to determine which of the five classical ballet positions is the most demanding regarding muscular activity, values of external rotation in the hip joints, angular values of foot progression as well as the inclination (tilt) of the pelvis in the sagittal plane. Methods: In this cross-sectional study, 14 female pre-professional ballet dancers (aged 11–16) participated. Participants were tasked with the sequential adoption of five classical ballet positions (CP1–CP5). The electromyographic activity of the muscles of the trunk and the lower limb was recorded with surface electrodes. Kinematic data including hip and knee external rotation, foot progression angle and pelvic tilt were collected using a motion capture system. Results: Symmetric positions CP1 and CP2 were not as demanding as asymmetric CP3–CP5. Higher values of hip and foot external rotation without greater muscular effort in CP2 than CP1 was noticed. Considering asymmetric positions, CP3 did not trigger a greater activity of hip or foot muscular groups than CP4 and CP5. CP4 was characterised by the greatest pelvic anterior tilt and the lowest activity of GM in the forward lower limb. In CP5, forward lower limb entailed a higher activity of muscles supporting the foot than in the remaining positions. Conclusion: In terms of biomechanics, the most demanding classical ballet position in pre-professional dancers is CP4, followed by CP5, CP3, CP1 and CP2. This finding can be applied in educational methodology of dancers, figure skaters, synchronized swimmers, acrobatic gymnasts, rhythmic gymnasts or cheerleaders.

4

Effect of a task’s postural demands on medial longitudinal arch deformation and activation of foot intrinsic and extrinsic musculatur

Kurihara Toshiyuki, Rowley Michael, Reischl Stephen, Baker Lucinda, Kulig Kornelia

Acta of Bioengineering and Biomechanics

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2020

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Vol. 22, no. 4

23--29

EN

It is not well established how motion and muscle activation of the medial longitudinal arch (MLA) of the foot vary under different loading conditions. Intrinsic and extrinsic foot muscles may play a role in postural control, which may be investigated by comparing loading tasks with differing postural demands. The objective of this study was to investigate the interaction of MLA flexibility and loading task on muscle activation. Methods: Twenty healthy adults completed two instrumented single-foot loading tasks: controlled external load of 50% body weight while sitting and bilateral standing. Fine-wire intramuscular and surface electromyography collected flexor hallucis brevis, abductor hallucis, tibialis posterior, flexor hallucis longus, tibialis anterior, and peroneus longus activation. MLA deformation was measured as a percent change in navicular height with loading. Results: During seated external loading, greater MLA deformation was associated with greater muscle activation for all instrumented muscles (R2 = 0.224–0.303, p < 0.05) except for tibialis anterior. During bilateral stance, there were no correlations between MLA deformation and muscle activation. Activation of all extrinsic muscles except for tibialis anterior were greater during bilateral standing than during external loading ( p = 0.002–0.013), indicating activation of these muscles was caused by postural demands of the standing task, not simply load. Conclusions: MLA deformation and muscle activation are strongly task-dependent.

5

Single channel EMG-based continuous terrain identification with simple classifier for lower limb prosthesis

Gupta Rohit, Agarwal Ravinder

Biocybernetics and Biomedical Engineering

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2019

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Vol. 39, no. 3

775--788

EN

The focus of the present research endeavour is to propose a single channel Electromyogram (EMG) signal driven continuous terrain identification method utilizing a simple classifier. An iterative feature selection algorithm has also been proposed to provide effective information to the classifiers. The proposed method has been validated on EMG signal of fifteen subjects and ten subjects for three and five daily life terrains respectively. Feature selection algorithm has significantly improved the identification accuracy (ANOVA, p-value < 0.05) as compared to principal component analysis (PCA) technique. The average identification accuracies obtained by Support Vector Machine (SVM), Linear Discriminant Analysis (LDA) and Neural Network (NN) classifiers are 96.83 ± 0.28%, 97.45 ± 0.32% and 97.61 ± 0.22% respectively. Subject wise performance (five subjects) of individually trained classifiers shows no significant degradation and difference in performance among the subjects even for the untrained data (ANOVA, p-value > 0.05). The study has been extended to dual muscle approach for terrain identification. However, the proposed algorithm has shown similar performance even with the single muscle approach (ANOVA, p-value > 0.05). The outcome of the proposed continuous terrain identifi-cation method shows a pronounced potential in efficient lower limb prosthesis control.

6

Szpala Agnieszka

Acta of Bioengineering and Biomechanics

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2019

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Vol. 21, no. 4

139--146

EN

Increased reaction time and asymmetrical force generation in muscles may elevate the risk of falling among seniors. Therefore, it seems useful to analyze the symmetry of strength and amplitude parameters that evaluate neuromuscular control. The aim of the study was to evaluate force parameters for the quadriceps and biceps femoris muscles in young and older women performing maximal voluntary contraction. Methods: Fifty women (1 group in their twenties and the other in their sixties) participated in the study. The study used surface electromyography methodology and measured peak torque under static conditions. Electromyographic signals and peak torque were recorded separately in knee extensors and flexors of the right and left lower limbs after a visual signal. The following parameters were selected for analysis: 1) maximum the electromyographic amplitude signal; 2) peak torque; 3) rate of torque development; 4) relative force; and 5) “flexor–extensor” ratio. Results: The analysis demonstrated a decrease in the values of all parameters in the elderly group and symmetry in EMG amplitude in both the younger and older women. Asymmetry was found in the group of elderly women for peak torque and the relative force for knee flexors and “flexor–extensor” ratio. Conclusions: The decline in values of force parameters in knee flexors and their asymmetry (not extensors) revealed in the elderly group might prove an important factor in the assessment of risk factors for falling among the elderly.

7

Rozpoznawanie ruchu palców na podstawie analizy elektromiogramu

Sikora M., Paszkiel S.

Pomiary Automatyka Robotyka

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2018

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R. 22, nr 2

11--16

PL

W artykule przedstawiono informacje dotyczące systemu umożliwiającego rozpoznawanie ruchu palców na podstawie dwóch sygnałów elektromiograficznych (EMG). W chwili obecnej system pozwala rozróżnić czy wykonany był ruch palcem wskazującym, środkowym, serdecznym lub małym. W dalszej części artykułu prezentowane są wyniki działania systemu oraz możliwe kierunki rozwoju.

EN

This paper discusses the system that allows to recognition of fingers movement based on a electromyogram (EMG). At the moment it can distinguish between the movement of pinky finger, ring finger, middle finger and index finger. The article presents the results of research on the effectiveness of the system as well as further development possibilities.

8

Neuromechanical control in submaximal drop jumps: The effects of volitional effort demands and drop height magnitude on soleus muscle activation

Mrdakovic V., Pazin N., Vulovic R., Filipovic N., Ilic D.

Acta of Bioengineering and Biomechanics

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2018

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Vol. 20, no. 4

101--111

EN

The purpose of this study was to investigate soleus muscle activation during different phases of drop jump performed at submaximal levels of volitional effort and drop height magnitude. Methods: Fifteen professional volleyball players with minimum of eight years of experience in jumping activities participated in the study. Experimental protocol involved executing submaximal drop jumps at three levels of volitional effort (i.e., 65, 80 and 95% of the maximal height of jump). All submaximal drop jumps were done from three drop heights (20, 40 and 60 cm). The soleus muscle activation was monitored during four jump phases: pre-activation phase before touchdown, early contact phase upon touchdown, early and late push-off phase. Results: The results indicate that volitional effort level did not change the muscle activation during pre activation and early contact phase, but only in early and late push-off phase ( p ≤ 0.05). Conversely, it was observed that muscle activation during all phases of drop jump was adapted to the increased intensity of the external load caused by increasing of drop height magnitude ( p ≤ 0.01). Conclusions: The findings of the present study suggested that soleus muscle activation has selective responses to internal load (i.e., volitional effort level) and external load (i.e., drop height magnitude) intensities when drop jump is executing with submaximal effort.

9

Influence of dopaminergic treatment on resting elbow joint angle control mechanisms in patients with Parkinson’s disease – a preliminary report

Marusiak J., Jaskólska A., Budrewicz S., Koszewicz M., Andrzejewska R., Kisiel-Sajewicz K., Jaskólski A.

Acta of Bioengineering and Biomechanics

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2018

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Vol. 20, no. 4

75--82

EN

Heightened tonic stretch reflex contributes to increased muscle tone and a more-flexed resting elbow joint angle (EJA) in patients with Parkinson’s disease (PD). Dopaminergic medication restores central nervous system (CNS) functioning and decreases resting muscle electrical and mechanical activities. This study aimed to evaluate the effects of dopaminergic medication on parkinsonian rigidity, resting EJA, resting electrical activity (electromyography, EMG) and mechanical properties (myotonometry, MYO) of elbow flexor muscles and the associations of EJA with these muscles resting electrical activity and mechanical properties in PD patients. We also evaluated a relationship between dopaminergic treatment dose and these outcome measures values. Methods: Ten PD patients (age 68 ± 10.1 years; body mass 70 ± 16.8 kg; height 162 ± 6.6 cm; illness duration 9 ± 4.5 years) were tested during medication on- and off-phases. Resting EJA, myotonometric muscle stiffness (S-MYO) and root mean square electromyogram amplitude (RMS-EMG) were recorded from relaxed biceps brachii and brachioradialis muscles. Based on the above parameters, we also calculated the EJA/S-MYO ratio and EJA/RMS-EMG ratio. Parkinsonian rigidity was assessed using the motor section of the Unified Parkinson’s Disease Rating Scale. Results: EJA, EJA/S-MYO ratio, and EJA/RMS-EMG ratio were increased and S-MYO, RMS-EMG, and parkinsonian rigidity were decreased during the medication on-phase compared with the off-phase. In addition, the dopaminergic treatment dose was negatively correlated with S-MYO and RMS-EMG, and positively correlated with EJA/SMYO and EJA/RMS-EMG ratios. Conclusions: We conclude that dopaminergic medication-induced improvements in resting elbow joint angle in tested patients with PD are related to changes in their muscle electrical and mechanical properties.

10

Effects of magnetostimulation on muscle activity and pain in edentulous adults with temporomandibular disorders

Rój R., Chladek G., Wyszyńska M., Morawiec T., Kasperski J.

Acta of Bioengineering and Biomechanics

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2018

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Vol. 20, no. 2

89--99

EN

Introduction: Multifactorial aetiologies of painful temporomandibular disorders (TMD) have an impact on correct diagnosis and consequently prevent proper treatment. Aim of the study: The aim of the study was to evaluate the effect of magnetic stimulation on electromyographic activity in temporal muscles and masseters in patients using occlusal splints. Materials and methods: The examined group consisted of 40 edentulous patients with TMD. The patients were examined based on Helkimo Index. Next, electromyographic activity of the temporal muscle and masseter were investigated using 8-channel surface electromyography. All patients received acrylic occlusal splints for 12 weeks. The group qualified for the study included 20 randomized patients, whose therapy was additionally carried out by extremely low-frequency magnetic fields for a period of 21 days. Following examinations were conducted after 3, 6 and 12 weeks with surface electromyography recording of the examined muscles. Patients received occlusal splint corrections using the T-Scan III system. The clinical evaluation of TMD was analysed using Helkimo index and VAS scale before and after the treatment. All the data were analysed using Statistica 12.5 PL. Results: Patients with combination therapy had lower asymmetry of temporal muscle activity. Conclusions: Combination therapy using magnetic stimulation reduced intensity of pain in patients with TMD and decreased values of the Helkimo indices.

11

Programowa identyfikacja wybranych zakłóceń zarejestrowanych przy pomiarze sygnału EMG

Krawiecki Z., Szałkiewicz S., Hulewicz A., Parzych J.

Poznan University of Technology Academic Journals. Electrical Engineering

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2017

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No. 89

219--228

PL

W artykule opisane zostały wybrane zagadnienia związane z identyfikacją zakłóceń zarejestrowanych wraz z sygnałem bioelektrycznym z mięśni człowieka. Zaprezentowany algorytm wykrywania zakłóceń dotyczy identyfikacji składowych w widmie sygnału, które pochodzą od sieci energetycznej i urządzeń elektrycznych pracujących w otoczeniu obiektu badań. Realizacja założonego celu identyfikacji zakłóceń została wykonana poprzez opracowanie algorytmu i napisanie programu do analizy wyników pomiarów. Na przykładzie wybranych plików z wynikami pomiarów przeprowadzone zostały testy działania algorytmu identyfikacji i napisanej w środowisku Matlab aplikacji.

EN

In the paper, the selected problems that are associated with the identification of interferences registered with a bioelectrical signal of human muscles. The presented algorithm detects interferences related to the identification component in the spectrum of the signal. These disturbances are from the power network as well as any electrical equipment. The algorithm has been designed and a software for analysis of measurement results has been made. Using the selected files concerning the results, operation tests on the algorithm and Matlab application were realized.

12

Electromyography and mechanomyography signal recognition: Experimental analysis using multi-way array decomposition methods

Wołczowski A., Zdunek R.

Biocybernetics and Biomedical Engineering

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2017

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Vol. 37, no. 1

103--113

EN

In this study, we considered the problem of controlling a prosthetic hand with noisy electromyography (EMG) and mechanomyography (MMG) signals. Several dimensionality reduction methods were analyzed to assess their efficiency at classifying these signals, which were registered during the performance of grasping movements with various objects. Using the cross-validation technique, we compared various dimensionality reduction methods, such as principal components analysis, nonnegative matrix factorization, and some tensor decomposition models. The experimental results demonstrated that the high-est classification accuracy (exceeding 95% for all subjects when classifying 11 grasping movements) and lowest computational complexity were obtained when higher-order singular value decomposition was applied to a multi-way array of multi-channel spectrograms, where the temporal EMG/MMG signals from all channels were concatenated.

13

Comparative evaluation of EMG signal features for myoelectric controlled human arm prosthetics

Karabulut D., Ortes F., Arslan Y. Z., Adli M. A.

Biocybernetics and Biomedical Engineering

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2017

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Vol. 37, no. 2

326--335

EN

Myoelectric controlled human arm prosthetics have shown a promising performance with regards to the supplementation of the basic manipulation requirements for amputated people over recent years. However these assistive devices still have important restrictions in enabling amputated people to perform rather sophisticated or functional movements. Surface electromyography (EMG) is used as the control signal to command such prosthetic devices to ensure the amputated people to compensate their fundamental movement patterns. The ability of extraction of clear and certain neural information from EMG signals is a critical issue in fine control of hand prosthesis movements. Various signal processing methods have been employed for feature extraction from EMG signals. In this study, it was aimed to comparatively evaluate the widely used time domain EMG signal features, i.e., integrated EMG (IEMG), root mean square (RMS), and waveform length (WL) in estimation of externally applied forces to human hands. Once the signal features were extracted, classification process was applied to predict the external forces using artificial neural networks (ANN). EMG signals were recorded during two types of muscle contraction: (i) isometric and isotonic, and (ii) anisotonic and anisometric contractions. Experiments were implemented by six healthy subjects from the muscles that are proximal to the upper body, i.e., biceps brachii, triceps brachii, pectorialis major and trapezius. The force prediction results obtained from the ANN were statistically evaluated and, merits and shortcomings of the features were discussed. Findings of the study are expected to provide better insight regarding control structure of the EMG-based motion assistive devices.

14

A longitudinal assessment of myoelectric activity, postural sway, and low-back pain during pregnancy

Moreira L. S., Elias L. A., Gomide A. B., Vieira M. F., Do Amaral W. N.

Acta of Bioengineering and Biomechanics

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2017

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Vol. 19, no. 3

77--83

EN

The present study aimed at investigating the control of upright quiet standing in pregnant women throughout pregnancy, and whether low-back pain exerts influence on this motor task. Methods: Myoelectric signals from postural muscles and stabilometric data were collected from 15 non-pregnant and 15 pregnant women during upright quiet standing. Electromyogram envelopes and center of pressure metrics were evaluated in the control group, as well as in pregnant women in their first and third trimester of pregnancy. A correlation analysis was performed between the measured variables and a low-back pain disability index. Results: Pregnant women exhibited a decreased maximum voluntary isometric activity for all postural muscles evaluated. Additionally, the activity of lumbar muscles during the postural task was significantly higher in the pregnant women in comparison to the non-pregnant controls. The soleus muscle maintained its activity at the same level as the gestation progressed. Higher postural oscillations were observed in the anteroposterior direction while mediolateral sway was reduced in the third trimester of pregnancy. No correlation was detected between the lowback pain disability index and neuromechanical variables. Conclusion: This study provides additional data regarding the functioning and adaptations of the postural control system during pregnancy. Also, we provide further evidence that postural control during quiet standing cannot be used to predict the occurrence of low-back pain. We hypothesize that the modifications in the neural drive to the muscles, as well as in postural sway may be related to changes in the biomechanics and hormonal levels experienced by the pregnant women.

15

Development of statistical models for predicting muscle and mental activities during repetitive precision tasks

Zadry H. R., Dawal S. Z. M., Taha Z.

International Journal of Occupational Safety and Ergonomics

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2016

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Vol. 22, No. 3

374--383

EN

This study was conducted to develop muscle and mental activities on repetitive precision tasks. A laboratory experiment was used to address the objectives. Surface electromyography was used to measure muscle activities from eight upper limb muscles, while electroencephalography recorded mental activities from six channels. Fourteen university students participated in the study. The results show that muscle and mental activities increase for all tasks, indicating the occurrence of muscle and mental fatigue. A linear relationship between muscle activity, mental activity and time was found while subjects were performing the task. Thus, models were developed using those variables. The models were found valid after validation using other students’ and workers’ data. Findings from this study can contribute as a reference for future studies investigating muscle and mental activity and can be applied in industry as guidelines to manage muscle and mental fatigue, especially to manage job schedules and rotation.

16

An experimental study to evaluate musculoskeletal disorders and postural stress of female craftworkers adopting different sitting postures

Maity P., De S., Pal A., Dhara P. C.

International Journal of Occupational Safety and Ergonomics

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2016

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Vol. 22, No. 2

257--266

EN

This study aimed to evaluate musculoskeletal disorders (MSDs) and postural stress among female craftworkers. The study was carried out on 75 adult female craftworkers in different districts of West Bengal. The prevalence of MSDs, body part discomfort (BPD) rating and body joint angles of the workers were evaluated with standard methods. Electromyography (EMG) of the shoulder and back muscles was recorded with the BIOPAC system. The prevalence of MSDs, BPD rating and deviation of joint angle were comparatively lower in the case of sitting on the floor with folded legs than squatting and sitting on the floor with stretched legs postures. The EMG and rms values of the shoulder and back muscles were comparatively lower in this posture. Therefore, it was concluded that sitting on the floor with folded legs was less hazardous and it imposed less postural stress in comparison to other sitting postures.

17

Bioelectrical activity of the pelvic floor muscles after 6-week biofeedback training in nulliparous continent women

Chmielewska D., Stania M., Smykla A., Kwaśna K., Błaszczak E., Sobota G., Skrzypulec-Plinta V.

Acta of Bioengineering and Biomechanics

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2016

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Vol. 18, no. 3

105--113

EN

Purpose: The aim of the study was to evaluate the effects of a 6-week sEMG-biofeedback-assisted pelvic floor muscle training program on pelvic floor muscle activity in young continent women. Methods: Pelvic floor muscle activity was recorded using a vaginal probe during five experimental trials. Biofeedback training was continued for 6 weeks, 3 times a week. Muscle strenghtening and endurance exercises were performed alternately. SEMG (surface electromyography) measurements were recorded on four different occasions: before training started, after the third week of training, after the sixth week of training, and one month after training ended. Results: A 6-week sEMG-biofeedback-assisted pelvic floor muscle training program significantly decreased the resting activity of the pelvic floor muscles in supine lying and standing. The ability to relax the pelvic floor muscles after a sustained 60-second contraction improved significantly after the 6-week training in both positions. SEMG-biofeedback training program did not seem to affect the activity of the pelvic floor muscles or muscle fatigue during voluntary pelvic floor muscle contractions. Conclusions: SEMG-biofeedback-assisted pelvic floor muscle training might be recommended for physiotherapists to improve the effectiveness of their relaxation techniques.

18

Application of the Teager Kaiser Energy Operator in an autonomous burst detector to create onset and offset profiles of forearm muscles during reach-to-grasp movements

Krabben T., Prange G. B., Kobus H. J., Rietman J. S., Buurke J. H.

Acta of Bioengineering and Biomechanics

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2016

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Vol. 18, no. 4

135--144

EN

Purpose: The primary aim of this study is to investigate the potential benefit of the Teager–Kaiser Energy Operator (TKEO) as data pre-processor, in an autonomous burst detection method to classify electromyographic signals of the (fore)arm and hand. For this purpose, optimal settings of the burst detector, leading to minimal detection errors, need to be known. Additionally, the burst detector is applied to real muscle activity recorded in healthy adults performing reach-to-grasp movements. Methods: The burst detector was based on the Approximated Generalized Likelihood Ratio (AGLR). Simulations with synthesized electromyographic (EMG) traces with known onset and offset times, yielded optimal settings for AGLR parameters “window width” and “threshold value” that minimized detection errors. Next, comparative simulations were done with and without TKEO data pre-processing. Correct working of the burst detector was verified by applying it to real surface EMG signals obtained from arm and hand muscles involved in a submaximal reach-to-grasp task, performed by healthy adults. Results: Minimal detection errors were found with a window width of 100 ms and a detection threshold of 15. Inclusion of the TKEO contributed significantly to a reduction of detection errors. Application of the autonomous burst detector to real data was feasible. Conclusions: The burst detector was able to classify muscle activation and create Muscle Onset Offset Profiles (MOOPs) autonomously from real EMG data, which allows objective comparison of MOOPs obtained from movement tasks performed in different conditions or from different populations. The TKEO contributed to improved performance and robustness of the burst detector.

19

A new simple local muscle recovery model and its theoretical and experimental validation

Ma L., Zhang W., Wu S., Zhang Z.

International Journal of Occupational Safety and Ergonomics

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2015

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Vol. 21, No. 1

86--93

EN

This study was conducted to provide theoretical and experimental validation of a local muscle recovery model. Muscle recovery has been modeled in different empirical and theoretical approaches to determine work-rest allowance for musculoskeletal disorder (MSD) prevention. However, time-related parameters and individual attributes have not been sufficiently considered in conventional approaches. A new muscle recovery model was proposed by integrating time-related task parameters and individual attributes. Theoretically, this muscle recovery model was compared to other theoretical models mathematically. Experimentally, a total of 20 subjects participated in the experimental validation. Hand grip force recovery and shoulder joint strength recovery were measured after a fatiguing operation. The recovery profile was fitted by using the recovery model, and individual recovery rates were calculated as well after fitting. Good fitting values (r2 > .8) were found for all the subjects. Significant differences in recovery rates were found among different muscle groups (p < .05). The theoretical muscle recovery model was primarily validated by characterization of the recovery process after fatiguing operation. The determined recovery rate may be useful to represent individual recovery attribute.

20

The effects of training status and muscle action on muscle activation of the vastus lateralis

Trevino M. A., Herda T. J.

Acta of Bioengineering and Biomechanics

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2015

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Vol. 17, no. 4

107--114

EN

This study examined the electromyographic amplitude–force relationships for 5 (age = 19.20 ± 0.45 yrs) aerobically-trained, 5 (age = 25 ± 4.53 yrs) resistance-trained, and 5 (age = 21.20 ± 2.17 yrs) sedentary individuals. Participants performed an isometric trapezoidal muscle action at 60% maximal voluntary contraction of the leg extensors that included linearly increasing, steady force, and linearly decreasing muscle actions. Electromyography was recorded from the vastus lateralis. The b (slopes) and a (y-intercepts) terms were calculated from the natural log-transformed electromyographic amplitude–force relationships (linearly increasing and decreasing segments) for each participant. An average of the electromyographic amplitude was calculated for the entire steady force segment. The b terms for the resistance-trained (1.384 ± 0.261) were greater than the aerobically-trained (0.886 ± 0.130, P = 0.003) and sedentary (0.955 ± 0.105, P = 0.008) participants during the linearly increasing segment, whereas, there were no differences in b terms among training statuses for the linearly decreasing segment. The b terms for the resistance-trained were greater (P = 0.019) during the linearly increasing segment than decreasing segment (1.186 ± 0.181), however, the b terms for the aerobically-trained were lower (P = 0.017) during the linearly increasing than decreasing segment (1.054 ± 0.176). The a terms from the log-transformed electromyographic amplitude–force relationships and electromyographic amplitude during the steady force segment were not different among training statuses (P = 0.187, P = 0.910). The linearity of the electromyographic amplitude patterns of response (b terms) recording during increasing and decreasing muscle actions may provide insight on motor unit control strategy differences as a result of exercise training status and muscle action, however, the a terms of these patterns and electromyographic amplitude during a steady force contraction did not distinguish among training statuses.