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1.
Sensors (Basel) ; 21(11)2021 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-34205220

RESUMO

Force myography (FMG) is a method that uses pressure sensors to measure muscle contraction indirectly. Compared with the conventional approach utilizing myoelectric signals in hand gesture recognition, it is a valuable substitute. To achieve the aim of gesture recognition at minimum cost, it is necessary to study the minimum sampling frequency and the minimal number of channels. For purpose of investigating the effect of sampling frequency and the number of channels on the accuracy of gesture recognition, a hardware system that has 16 channels has been designed for capturing forearm FMG signals with a maximum sampling frequency of 1 kHz. Using this acquisition equipment, a force myography database containing 10 subjects' data has been created. In this paper, gesture accuracies under different sampling frequencies and channel's number are obtained. Under 1 kHz sampling rate and 16 channels, four of five tested classifiers reach an accuracy up to about 99%. Other experimental results indicate that: (1) the sampling frequency of the FMG signal can be as low as 5 Hz for the recognition of static movements; (2) the reduction of channel number has a large impact on the accuracy, and the suggested channel number for gesture recognition is eight; and (3) the distribution of the sensors on the forearm would affect the recognition accuracy, and it is possible to improve the accuracy via optimizing the sensor position.


Assuntos
Gestos , Miografia , Eletromiografia , Mãos , Humanos , Fenômenos Mecânicos , Contração Muscular
2.
Sensors (Basel) ; 21(11)2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-34205957

RESUMO

In this paper, we present a novel muscle synergy extraction method based on multivariate curve resolution-alternating least squares (MCR-ALS) to overcome the limitation of the nonnegative matrix factorization (NMF) method for extracting non-sparse muscle synergy, and we study its potential application for evaluating motor function of stroke survivors. Nonnegative matrix factorization (NMF) is the most widely used method for muscle synergy extraction. However, NMF is susceptible to components' sparseness and usually provides inferior reliability, which significantly limits the promotion of muscle synergy. In this study, MCR-ALS was employed to extract muscle synergy from electromyography (EMG) data. Its performance was compared with two other matrix factorization algorithms, NMF and self-modeling mixture analysis (SMMA). Simulated data sets were utilized to explore the influences of the sparseness and noise on the extracted synergies. As a result, the synergies estimated by MCR-ALS were the most similar to true synergies as compared with SMMA and NMF. MCR-ALS was used to analyze the muscle synergy characteristics of upper limb movements performed by healthy (n = 11) and stroke (n = 5) subjects. The repeatability and intra-subject consistency were used to evaluate the performance of MCR-ALS. As a result, MCR-ALS provided much higher repeatability and intra-subject consistency as compared with NMF, which were important for the reliability of the motor function evaluation. The stroke subjects had lower intra-subject consistency and seemingly had more synergies as compared with the healthy subjects. Thus, MCR-ALS is a promising muscle synergy analysis method for motor function evaluation of stroke patients.


Assuntos
Músculo Esquelético , Acidente Vascular Cerebral , Eletromiografia , Humanos , Projetos Piloto , Reprodutibilidade dos Testes
3.
Sensors (Basel) ; 21(12)2021 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-34207448

RESUMO

Classification of terrain is a vital component in giving suitable control to a walking assistive device for the various walking conditions. Although surface electromyography (sEMG) signals have been combined with inputs from other sensors to detect walking intention, no study has yet classified walking environments using sEMG only. Therefore, the purpose of this study is to classify the current walking environment based on the entire sEMG profile gathered from selected muscles in the lower extremities. The muscle activations of selected muscles in the lower extremities were measured in 27 participants while they walked over flat-ground, upstairs, downstairs, uphill, and downhill. An artificial neural network (ANN) was employed to classify these walking environments using the entire sEMG profile recorded for all muscles during the stance phase. The result shows that the ANN was able to classify the current walking environment with high accuracy of 96.3% when using activation from all muscles. When muscle activation from flexor/extensor groups in the knee, ankle, and metatarsophalangeal joints were used individually to classify the environment, the triceps surae muscle activation showed the highest classification accuracy of 88.9%. In conclusion, a current walking environment was classified with high accuracy using an ANN based on only sEMG signals.


Assuntos
Aprendizado Profundo , Caminhada , Eletromiografia , Humanos , Perna (Membro) , Músculo Esquelético
4.
Int J Mol Sci ; 22(11)2021 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-34199392

RESUMO

Coordination of four-limb movements during quadrupedal locomotion is controlled by supraspinal monoaminergic descending pathways, among which serotoninergic ones play a crucial role. Here we investigated the locomotor pattern during recovery from blockade of 5-HT7 or 5-HT2A receptors after intrathecal application of SB269970 or cyproheptadine in adult rats with chronic intrathecal cannula implanted in the lumbar spinal cord. The interlimb coordination was investigated based on electromyographic activity recorded from selected fore- and hindlimb muscles during rat locomotion on a treadmill. In the time of recovery after hindlimb transient paralysis, we noticed a presence of an unusual pattern of quadrupedal locomotion characterized by a doubling of forelimb stepping in relation to unaffected hindlimb stepping (2FL-1HL) after blockade of 5-HT7 receptors but not after blockade of 5-HT2A receptors. The 2FL-1HL pattern, although transient, was observed as a stable form of fore-hindlimb coupling during quadrupedal locomotion. We suggest that modulation of the 5-HT7 receptors on interneurons located in lamina VII with ascending projections to the forelimb spinal network can be responsible for the 2FL-1HL locomotor pattern. In support, our immunohistochemical analysis of the lumbar spinal cord demonstrated the presence of the 5-HT7 immunoreactive cells in the lamina VII, which were rarely 5-HT2A immunoreactive.


Assuntos
Locomoção/genética , Receptor 5-HT2A de Serotonina/genética , Receptores de Serotonina/genética , Traumatismos da Medula Espinal/genética , Animais , Ciproeptadina/farmacologia , Estimulação Elétrica , Eletromiografia , Membro Anterior/efeitos dos fármacos , Membro Anterior/fisiopatologia , Membro Posterior/efeitos dos fármacos , Membro Posterior/fisiopatologia , Humanos , Locomoção/efeitos dos fármacos , Região Lombossacral/fisiopatologia , Ratos , Receptor 5-HT2A de Serotonina/efeitos dos fármacos , Receptores de Serotonina/efeitos dos fármacos , Serotonina/genética , Serotonina/metabolismo , Antagonistas do Receptor 5-HT2 de Serotonina/farmacologia , Medula Espinal , Traumatismos da Medula Espinal/tratamento farmacológico , Traumatismos da Medula Espinal/patologia , Coluna Vertebral/efeitos dos fármacos , Coluna Vertebral/fisiopatologia
5.
Sensors (Basel) ; 21(13)2021 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-34206714

RESUMO

Robotic-assisted systems have gained significant traction in post-stroke therapies to support rehabilitation, since these systems can provide high-intensity and high-frequency treatment while allowing accurate motion-control over the patient's progress. In this paper, we tackle how to provide active support through a robotic-assisted exoskeleton by developing a novel closed-loop architecture that continually measures electromyographic signals (EMG), in order to adjust the assistance given by the exoskeleton. We used EMG signals acquired from four patients with post-stroke hand impairments for training machine learning models used to characterize muscle effort by classifying three muscular condition levels based on contraction strength, co-activation, and muscular activation measurements. The proposed closed-loop system takes into account the EMG muscle effort to modulate the exoskeleton velocity during the rehabilitation therapy. Experimental results indicate the maximum variation on velocity was 0.7 mm/s, while the proposed control system effectively modulated the movements of the exoskeleton based on the EMG readings, keeping a reference tracking error <5%.


Assuntos
Exoesqueleto Energizado , Articulação da Mão , Reabilitação do Acidente Vascular Cerebral , Eletromiografia , Mãos , Humanos , Músculos
6.
Sensors (Basel) ; 21(13)2021 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-34206753

RESUMO

Synchronous correlation brain and muscle oscillations during motor task execution is termed as functional coupling. Functional coupling between two signals appears with a delay time which can be used to infer the directionality of information flow. Functional coupling of brain and muscle depends on the type of muscle contraction and motor task performance. Although there have been many studies of functional coupling with types of muscle contraction and force level, there has been a lack of investigation with various motor task performances. Motor task types play an essential role that can reflect the amount of functional interaction. Thus, we examined functional coupling under four different motor tasks: real movement, intention, motor imagery and movement observation tasks. We explored interaction of two signals with linear and nonlinear information flow. The aim of this study is to investigate the synchronization between brain and muscle signals in terms of functional coupling and delay time. The results proved that brain-muscle functional coupling and delay time change according to motor tasks. Quick synchronization of localized cortical activity and motor unit firing causes good functional coupling and this can lead to short delay time to oscillate between signals. Signals can flow with bidirectionality between efferent and afferent pathways.


Assuntos
Músculo Esquelético , Análise e Desempenho de Tarefas , Eletroencefalografia , Eletromiografia , Contração Muscular
7.
Eur J Paediatr Dent ; 22(2): 129-134, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34238003

RESUMO

AIM: This prospective non-randomised case-control study analysed lip muscle activity after Lip Bumper (LB) treatment thought surface electromyography. METHODS: The study group was composed of 40 young patients with a mean age of 10 years and 1 month, treated with LB in the lower arch, while 40 children who did not undergo any treatment, matched for sex and age with the previous sample, constituted the control group. Measurements were performed at the beginning and after 1 year for both groups. Electromyographic recordings were obtained in rest position and during the swallowing of 50 ml of water. RESULTS: In the study group, after 1 year of LB treatment, a statistically significant decrease in values was found; specifically, in upper lip muscle activities at rest position with the appliance in situ (p <0.002) and both with (p <0.001) and without (p <0.001) the appliance for the lower lip. CONCLUSION: One year of LB treatment significantly reduced lip muscle activities at both rest position and during swallowing compared with the untreated sample. These results indicated a potential short-term of upper and lower lip muscle adaptation to the new balance induced by LB treatment.


Assuntos
Lábio , Músculos , Estudos de Casos e Controles , Criança , Eletromiografia , Músculos Faciais , Humanos , Estudos Prospectivos
8.
Sensors (Basel) ; 21(14)2021 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-34300408

RESUMO

Chronic pelvic pain (CPP) is a complex condition with a high economic and social burden. Although it is usually treated with botulinum neurotoxin type A (BoNT/A) injected into the pelvic floor muscles (PFM), its effect on their electrophysiological condition is unknown. In this study, 24 CPP patients were treated with BoNT/A. Surface electromyographic signals (sEMG) were recorded at Weeks 0 (infiltration), 8, 12 and 24 from the infiltrated, non-infiltrated, upper and lower PFM. The sEMG of 24 healthy women was also recorded for comparison. Four parameters were computed: root mean square (RMS), median frequency (MDF), Dimitrov's index (DI) and sample entropy (SampEn). An index of pelvic electrophysiological impairment (IPEI) was also defined with respect to the healthy condition. Before treatment, the CPP and healthy parameters of almost all PFM sides were significantly different. Post-treatment, there was a significant reduction in power (MDF), lower fatigue index (SampEn) in all sites in patients, mainly during PFM contractions, which brought their electrophysiological condition closer to that of healthy women (

Assuntos
Toxinas Botulínicas Tipo A , Dor Crônica , Toxinas Botulínicas Tipo A/uso terapêutico , Dor Crônica/tratamento farmacológico , Eletromiografia , Feminino , Humanos , Contração Muscular , Diafragma da Pelve , Dor Pélvica/tratamento farmacológico
9.
Sensors (Basel) ; 21(14)2021 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-34300440

RESUMO

A statistical method for exploratory data analysis based on 2D and 3D area under curve (AUC) diagrams was developed. The method was designed to analyze electroencephalogram (EEG), electromyogram (EMG), and tremorogram data collected from patients with Parkinson's disease. The idea of the method of wave train electrical activity analysis is that we consider the biomedical signal as a combination of the wave trains. The wave train is the increase in the power spectral density of the signal localized in time, frequency, and space. We detect the wave trains as the local maxima in the wavelet spectrograms. We do not consider wave trains as a special kind of signal. The wave train analysis method is different from standard signal analysis methods such as Fourier analysis and wavelet analysis in the following way. Existing methods for analyzing EEG, EMG, and tremor signals, such as wavelet analysis, focus on local time-frequency changes in the signal and therefore do not reveal the generalized properties of the signal. Other methods such as standard Fourier analysis ignore the local time-frequency changes in the characteristics of the signal and, consequently, lose a large amount of information that existed in the signal. The method of wave train electrical activity analysis resolves the contradiction between these two approaches because it addresses the generalized characteristics of the biomedical signal based on local time-frequency changes in the signal. We investigate the following wave train parameters: wave train central frequency, wave train maximal power spectral density, wave train duration in periods, and wave train bandwidth. We have developed special graphical diagrams, named AUC diagrams, to determine what wave trains are characteristic of neurodegenerative diseases. In this paper, we consider the following types of AUC diagrams: 2D and 3D diagrams. The technique of working with AUC diagrams is illustrated by examples of analysis of EMG in patients with Parkinson's disease and healthy volunteers. It is demonstrated that new regularities useful for the high-accuracy diagnosis of Parkinson's disease can be revealed using the method of analyzing the wave train electrical activity and AUC diagrams.


Assuntos
Doença de Parkinson , Área Sob a Curva , Análise de Dados , Eletromiografia , Humanos , Doença de Parkinson/diagnóstico , Tremor
10.
Sensors (Basel) ; 21(14)2021 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-34300485

RESUMO

Fragile X Syndrome (FXS), the leading form of inherited intellectual disability and autism, is characterized by specific musculoskeletal conditions. We hypothesized that gait analysis in FXS could be relevant for the evaluation of motor control of gait, and help the understanding of a possible correlation between functional and intellectual abilities. Typical deficits in executive control and hyperactivity have hampered the use of standard gait analysis. The aim of our study was to quantitatively assess musculoskeletal alterations in FXS children in standard ambulatory conditions, in a friendly environment. Ten FXS children and sixteen controls, with typical neurodevelopment, were evaluated through four synchronized video cameras and surface electromyography; lower limb joints rotations, spatiotemporal parameters, duration of muscle contraction, activation timing and envelope peaks were determined. Reliability and repeatability of the video based kinematics analysis was assessed with respect to stereophotogrammetry. The Kruskal-Wallis Test (p < 0.05) or SPM1D were used to compare different groups of subjects. Results show a consistently altered gait pattern associated with abnormal muscle activity in FXS subjects: reduced knee and excessive hip and ankle flexion, and altered duration and activity onset on all the recorded muscles (Rectus/Biceps Femoris, Tibialis Anterior, Gastrocnemius Lateralis). Results of this study could help with planning personalized rehabilitations.


Assuntos
Marcha , Músculo Esquelético , Fenômenos Biomecânicos , Criança , Eletromiografia , Estudos de Viabilidade , Humanos , Amplitude de Movimento Articular , Reprodutibilidade dos Testes
11.
Sensors (Basel) ; 21(14)2021 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-34300581

RESUMO

This study aimed to evaluate motor unit recruitment during submaximal voluntary ramp contraction in the medial head of the gastrocnemius muscle (MG) by high-density spatial electromyography (SEMG) before and after static stretching (SS) in healthy young adults. SS for gastrocnemius was performed in 15 healthy participants for 2 min. Normalized peak torque by bodyweight of the plantar flexor, muscle activity at peak torque, and muscle activation patterns during ramp-up task were evaluated before and after SS. Motor unit recruitment during the submaximal voluntary contraction of the MG was measured using SEMG when performing submaximal ramp contractions during isometric ankle plantar flexion from 30 to 80% of the maximum voluntary contraction (MVC). To evaluate the changes in the potential distribution of SEMG, the root mean square (RMS), modified entropy, and coefficient of variation (CV) were calculated from the dense surface EMG data when 10% of the MVC force was applied. Muscle activation patterns during the 30 to 80% of MVC submaximal voluntary contraction tasks were significantly changed from 50 to 70% of MVC after SS when compared to before. The variations in motor unit recruitment after SS indicate diverse motor unit recruitments and inhomogeneous muscle activities, which may adversely affect the performance of sports activities.


Assuntos
Exercícios de Alongamento Muscular , Tornozelo , Eletromiografia , Humanos , Contração Isométrica , Contração Muscular , Músculo Esquelético , Torque , Adulto Jovem
12.
J Contemp Dent Pract ; 22(5): 522-526, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-34318771

RESUMO

AIM: The aim of this study was to determine the lateral pterygoid muscle (LPM) in relation to preauricular skin measured from computed tomography (CT) scan measurements. MATERIALS AND METHODS: CT scans of 160 patients aged between 18 and 75 years were retrospectively collected and analyzed, and the distances were measured to determine the location of the LPM center in relation to the preauricular skin. On axial CT crossing the maximum muscle width, two lines [the first line is below the center of the zygomatic arch (first position), while the second line was 5 mm posterior to the first one (second position)] were drawn from the preauricular skin to the medial border and then extended to the lateral border of the muscle. These measurements were used to calculate the distance to the center of the muscle mathematically. Data were statistically analyzed, and the differences between both genders and both sides were investigated. The level of significance was set at p-value <0.05. RESULTS: Males displayed larger mean values in two positions (36.6 ± 2.25 and 35.97 ± 4.19, respectively) than females (33.66 ± 4.46 and 32.80 ± 3.21, respectively). The difference between both genders was found to be statistically significant. Measurements on the right side were also larger than those on the left side, but with no significant difference. CONCLUSION: LPM center can be approached safely in males by inserting the needle about 36 mm at the first position and 33 mm at the second position. However, in females, these distances are located 3 mm shorter in both positions. CLINICAL SIGNIFICANCE: The outcome of this study will provide the clinicians with measurements that can help in directing the needle or electromyography (EMG) electrode during the extraoral injection technique of the LPM. How to cite this article: Al-Tairi NH, Al-Sharaee YA, Alhajj MN. Lateral Pterygoid Muscle Location in Relation to Preauricular Skin Measured from CT Scans among a Sample of Yemeni Adults. J Contemp Dent Pract 2021;22(5):522-526.


Assuntos
Músculos Pterigoides , Zigoma , Adolescente , Adulto , Idoso , Eletromiografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Músculos Pterigoides/diagnóstico por imagem , Estudos Retrospectivos , Tomografia Computadorizada por Raios X , Adulto Jovem
13.
Artigo em Inglês | MEDLINE | ID: mdl-34198674

RESUMO

BACKGROUND: This study compared the muscle activity and six repetition maximum (6-RM) loads in bench press with narrow, medium, and wide grip widths with sub-group comparisons of resistance-trained (RT) and novice-trained (NT) men. METHODS: After two familiarization sessions, twenty-eight subjects lifted their 6-RM loads with the different grip widths with measurement of electromyographic activity. RESULTS: Biceps brachii activity increased with increasing grip width, whereas wide grip displayed lower triceps brachii activation than medium and narrow. In the anterior deltoid, greater activity was observed using a medium compared to narrow grip. Similar muscle activities were observed between the grip widths for the other muscles. For the RT group, greater biceps brachii activity with increasing grip width was observed, but only greater activity was observed in the NT group between narrow and wide. Comparing wide and medium grip width, the RT group showed lower triceps activation using a wide grip, whereas the NT group showed lower anterior deltoid activation using a narrow compared to medium grip. Both groups demonstrated lower 6-RM loads using a narrow grip compared to the other grips. CONCLUSION: Grip widths affect both 6-RM loads and triceps brachii, biceps brachii, and anterior deltoid activity especially between wide and narrow grip widths.


Assuntos
Treinamento de Força , Levantamento de Peso , Eletromiografia , Força da Mão , Humanos , Masculino , Força Muscular , Músculo Esquelético
14.
Medicine (Baltimore) ; 100(25): e26357, 2021 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-34160406

RESUMO

ABSTRACT: To investigate the effect of core stability training on nonspecific low back pain (NSLBP) in nurses.The data were collected retrospectively by reviewing the patient's medical records and pain questionnaires in our rehabilitation center. A total of 40 nurses with NSLBP were included and divided into observation group and control group. Each group were given routine health education for NSLBP. Core stability training was performed in observation group for 4 weeks. Surface electromyography (sEMG) evaluation of erector spine and multifidus muscle, pain Numeric Rating Scale (NRS) and Japanese Orthopaedic Association (JOA) scores were evaluated and analyzed before and 4 weeks after intervention.There was no significant difference of NRS score and JOA score between two groups before intervention (P > .05, respectively). The NRS and JOA scores were significantly improved in both two groups after 4 weeks of intervention (P < .05, respectively). Moreover, the improvement of NRS and JOA scores in the observation group were better than those of the control group (P < .05, respectively). No significant difference of average electromyography (AEMG) or median frequency (MF) were noted between the healthy side and the affected side in both groups before or after intervention (P > .05, respectively). After 4 weeks of intervention, the AEMG of the healthy and the affected side of the two groups showed an improved trend without significant difference (P > .05, respectively). The MF of affected side was significantly higher 4 weeks after intervention than those before treatment in the observation and control group (P < .05, respectively).Core stability training can alleviate pain, improve the fatigue resistance of the core muscles and the balance of the functions of bilateral multifidus muscles in nurses with NSLBP.


Assuntos
Terapia por Exercício/métodos , Dor Lombar/terapia , Força Muscular/fisiologia , Enfermeiras e Enfermeiros , Músculos Paraespinais/fisiopatologia , Adulto , Estudos de Casos e Controles , Eletromiografia , Feminino , Seguimentos , Humanos , Dor Lombar/diagnóstico , Dor Lombar/fisiopatologia , Masculino , Medição da Dor , Estudos Retrospectivos , Resultado do Tratamento , Adulto Jovem
15.
Exp Brain Res ; 239(7): 2251-2260, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34059935

RESUMO

Ipsilateral motor pathways from the contralesional hemisphere to the paretic limbs may be upregulated to compensate for impaired function after stroke. Onset latency and duration of motor evoked potentials (MEPs) evoked by transcranial magnetic stimulation (TMS) provide insight into compensatory pathways but have been understudied in the lower limb. This study assessed MEP onset latency and duration in the lower limb after stroke, and compared ipsilateral and contralateral MEPs in the paretic and non-paretic limb. We hypothesized that: (1) onset latency would be longer for ipsilateral than contralateral MEPs and longer for the paretic than the non-paretic limb, and (2) duration would be shorter for ipsilateral than contralateral MEPs and longer for the paretic than the non-paretic limb. Data were collected as a part of a pre-test of a randomized controlled trial. TMS was applied to the ipsilateral and contralateral hemisphere of the paretic and non-paretic limb. MEP onset latency and duration were calculated from the tibialis anterior. Thirty-five participants with chronic stroke were included in the final analysis. Onset latency was longer in the paretic than the non-paretic limb (~ 6.0 ms) and longer after ipsilateral than contralateral stimulation (~ 1.8 ms). Duration was longer in the paretic than the non-paretic limb (~ 9.2 ms) and longer after contralateral than ipsilateral stimulation (~ 5.2 ms). Ipsilateral MEPs may be elicited through ipsilateral pathways with fewer fibers with a higher activation threshold and/or greater spinal branching. MEPs from the paretic limb may reflect slower central motor conduction, peripheral changes, or changes in motor pathway.


Assuntos
Córtex Motor , Acidente Vascular Cerebral , Eletromiografia , Potencial Evocado Motor , Humanos , Músculo Esquelético , Acidente Vascular Cerebral/complicações , Estimulação Magnética Transcraniana
16.
Artigo em Inglês | MEDLINE | ID: mdl-34065333

RESUMO

Manual material handling (MMH) is commonly demanded in the manufacturing industry. Occupational muscle fatigue of the arm, shoulder, and back, which arise from MMH tasks, can cause work absences and low efficiency. The available literature presents the lack of the fatigue comparison between targeted muscles, on the same part or on different parts. The main aim of the present study was to evaluate and compare the fatigue of upper-body muscles during repetitive bending tasks, an experiment involving 12 male subjects has been conducted to simulate material handling during furniture board drilling. The vertical lifting distance was chosen to be the single independent variable, and the three levels were 0, 250, and 500 mm. Surface electromyography (sEMG) was used to measure the muscle fatigue of the biceps brachii, upper trapezius, and multifidus, while the sEMG parameters, including the normalized electromyographic amplitude (Normalized EA) and mean power frequency (MPF), of the target muscles were analyzed. The experimental results reveal that during the manual handling tasks, the biceps brachii was the most relaxed muscle, contributing the least muscle tension, while the multifidus was the most easily fatigued muscle. Furthermore, the EMG MPF fatigue threshold (MPFFT) of multifidus muscle tension was tested to estimate its maximum workload in the long-term muscle contraction. In conclusion, bending angle should be maintained to a small range or bending should even be avoided during material-handling tasks.


Assuntos
Remoção , Fadiga Muscular , Eletromiografia , Humanos , Masculino , Contração Muscular , Músculo Esquelético , Ombro
17.
Front Public Health ; 9: 612064, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34136448

RESUMO

The aim of this study was to investigate how the anterior and posterior muscles in the shank (Tibialis Anterior, Gastrocnemius Lateralis and Medialis), influence the level of minimum toe clearance (MTC). With aging, MTC deteriorates thus, greatly increasing the probability of falling or tripping. This could result in injury or even death. For this study, muscle activity retention taping (MART) was used on young adults, which is an accepted method of simulating a poor MTC-found in elderly gait. The subject's muscle activation was measured using surface electromyography (SEMG), and the kinematic parameters (MTC, knee and ankle joint angles) were measured using an optical motion capture system. Our results indicate that MART produces significant reductions in MTC (P < α), knee flexion (P < α) and ankle dorsiflexion (P < α), as expected. However, the muscle activity increased significantly, contrary to the expected result (elderly individuals should have lower muscle activity). This was due to the subject's muscle conditions (healthy and strong), hence the muscles worked harder to counteract the external restriction. Yet, the significant change in muscle activity (due to MART) proves that the shank muscles do play an important role in determining the level of MTC. The Tibialis Anterior had the highest overall muscle activation, making it the primary muscle active during the swing phase. With aging, the shank muscles (specifically the Tibialis Anterior) would weaken and stiffen, coupled with a reduced joint range of motion. Thus, ankle-drop would increase-leading to a reduction in MTC.


Assuntos
Marcha , Caminhada , Idoso , Fenômenos Biomecânicos , Eletromiografia , Humanos , Dedos do Pé , Adulto Jovem
18.
Artigo em Inglês | MEDLINE | ID: mdl-34068352

RESUMO

The aim of this study was to evaluate the muscle activities and subjective discomfort according to the heights of tasks and the lower-limb exoskeleton CEX (Chairless EXoskeleton), which is a chair-type passive exoskeleton. Twenty healthy subjects (thirteen males and seven females) participated in this experiment. The independent variables were wearing of the exoskeleton (w/ CEX, w/o CEX), working height (6 levels: 40, 60, 80, 100, 120, and 140 cm), and muscle type (8 levels: upper trapezius (UT), erector spinae (ES), middle deltoid (MD), triceps brachii (TB), biceps brachii (BB), biceps femoris (BF), rectus femoris (RF), and tibialis anterior (TA)). The dependent variables were EMG activity (% MVC) and subjective discomfort rating. When wearing the CEX, the UT, ES, RF, and TA showed lower muscle activities at low working heights (40-80 cm) than not wearing the CEX, whereas those muscles showed higher muscle activities at high working heights (100-140 cm). Use of the CEX had a positive effect on subjective discomfort rating at lower working heights. Generally, lower discomfort was reported at working heights below 100 cm when using the CEX. At working heights of 100-140 cm, the muscle activity when wearing the CEX tended to be greater than when not wearing it. Thus, considering the results of this study, the use of the lower-limb exoskeleton (CEX) at a working height of 40-100 cm might reduce the muscle activity and discomfort of whole body and decrease the risk of related disorders.


Assuntos
Exoesqueleto Energizado , Eletromiografia , Ergonomia , Feminino , Humanos , Extremidade Inferior , Masculino , Músculo Esquelético , Postura
19.
J Exp Biol ; 224(12)2021 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-34096594

RESUMO

The functional difference between the medial gastrocnemius (MG) and lateral gastrocnemius (LG) during walking in humans has not yet been fully established. Although evidence highlights that the MG is activated more than the LG, the link with potential differences in mechanical behavior between these muscles remains unknown. In this study, we aimed to determine whether differences in activation between the MG and LG translate into different fascicle behavior during walking. Fifteen participants walked at their preferred speed under two conditions: 0% and 10% incline treadmill grade. We used surface electromyography and B-mode ultrasound to estimate muscle activation and fascicle dynamics in the MG and LG. We observed a higher normalized activation in the MG than in the LG during stance, which did not translate into greater MG normalized fascicle shortening. However, we observed significantly less normalized fascicle lengthening in the MG than in the LG during early stance, which matched with the timing of differences in activation between muscles. This resulted in more isometric behavior of the MG, which likely influences the muscle-tendon interaction and enhances the catapult-like mechanism in the MG compared with the LG. Nevertheless, this interplay between muscle activation and fascicle behavior, evident at the group level, was not observed at the individual level, as revealed by the lack of correlation between the MG-LG differences in activation and MG-LG differences in fascicle behavior. The MG and LG are often considered as equivalent muscles but the neuromechanical differences between them suggest that they may have distinct functional roles during locomotion.


Assuntos
Músculo Esquelético , Caminhada , Fenômenos Biomecânicos , Eletromiografia , Humanos , Contração Muscular , Tendões
20.
BMC Neurol ; 21(1): 241, 2021 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-34172001

RESUMO

BACKGROUND: Sarcopenia is the age-related loss of muscle mass and strength. Undiagnosed late-onset neuromuscular disorders need to be considered in the differential diagnosis of sarcopenia. AIM: Based on emblematic case reports and current neuromuscular diagnostic guidelines for three common late-onset neuromuscular disorders, a differential diagnostic approach for geriatric patients presenting with a sarcopenic phenotype is given. METHODS: Patients over 65 years of age with sarcopenia, amyotrophic lateral sclerosis, inclusion body myositis and myotonic dystrophy type 2 were recruited. All patients were assessed for sarcopenia based on the revised European consensus definition. Patients with neuromuscular diseases were diagnosed according to the revised El Escorial criteria and the European neuromuscular centre criteria. Phenotypes and diagnostic criteria for all patients were summarized including their specific histopathological findings. RESULTS: All patients with neuromuscular diseases were positively screened for sarcopenia and classified as severe sarcopenic by means of assessment. The clinical phenotype, the evolution pattern of weakness and muscle atrophy combined with laboratory finding including electromyography could unquestionably distinguish the diseases. DISCUSSION: Neuromuscular disorders can manifest beyond the age of 65 years and misdiagnosed as sarcopenia. The most common diseases are inclusion body myositis, amyotrophic lateral sclerosis and myotonic dystrophy type 2. A diagnostic work-up for neuromuscular diseases ensures their correct diagnosis by clinical-, electrophysiological, histopathological, and genetic work-up. CONCLUSIONS: In geriatric patients with a focal or asymmetrical muscular weakness and atrophy, sarcopenia assessment should be extended with patient's history of disease course. Furthermore, concomitant diseases, analysis of serum creatine kinase, electrophysiological examination, and in selected patients muscle biopsy and gene analysis is needed to rule out a late-onset neuromuscular disorder.


Assuntos
Doenças Neuromusculares/diagnóstico , Sarcopenia/diagnóstico , Idoso , Idoso de 80 Anos ou mais , Esclerose Amiotrófica Lateral/diagnóstico , Diagnóstico Diferencial , Eletromiografia , Humanos , Distrofia Miotônica/diagnóstico
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