Search Results (607)

Objectives: The aim of this study was to evaluate the impact of four working heights on lumbar biomechanics during wall construction tasks, focusing on work-related musculoskeletal disorders (WMSDs). Methods: Fifteen young male participants performed simulated mortar-spreading and bricklaying tasks while actual body movements were recorded using Inertial Measurement Unit (IMU) sensors. Muscle activities of the lumbar erector spinae (ES), quadratus lumborum (QL), multifidus (MF), gluteus maximus (GM), and iliopsoas (IL) were estimated using a 3D musculoskeletal (MSK) model and measured via surface electromyography (sEMG). The analysis of variance (ANOVA) test was conducted to identify the significant differences in muscle activities across four working heights (i.e., foot, knee, waist, and shoulder). Results: Findings showed that working at foot-level height resulted in the highest muscle activity (7.6% to 40.6% increase), particularly in the ES and QL muscles, indicating an increased risk of WMSDs. The activities of the ES, MF, and GM muscles were statistically significant across both tasks and all working heights (p < 0.01). Conclusions: Both MSK and sEMG analyses indicated significantly lower muscle activities at knee and waist heights, suggesting these as the best working positions (47 cm to 107 cm) for minimizing the risk of WMSDs. Conversely, working at foot and shoulder heights was identified as a significant risk factor for WMSDs. Additionally, the similar trends observed between MSK simulations and sEMG data suggest that MSK modeling can effectively substitute for sEMG in future studies. These findings provide valuable insights into ergonomic work positioning to reduce WMSD risks among wall construction workers. Full article

The study of muscle activity as a function of vertical dimension has been extensively developed in the field of oral physiology. It involves asking subjects to open their mouths to a predetermined distance and then recording muscle activity in that position. Most studies perform this without accounting for physiological differences among patients. The objective of this study is to present a protocol for recording muscle activity at various mouth-opening levels using electromagnetic articulography (EMA) and surface electromyography (sEMG), normalizing opening degrees and muscle activity. Muscle activity recordings were obtained in the position of maximum intercuspation and maximum mouth opening. Based on these recordings, the position corresponding to 5–50% of maximum opening was calculated. EMA and sEMG recordings were performed at these levels. Muscle activity during maximum voluntary clenching was recorded and used to normalize the previous data. In all cases, three 5-second recordings were obtained. The analysis of muscle activity using EMA and sEMG did not present any complications. A slight difference was observed between the intended percentage of mouth opening and the actual percentage achieved. The method described in this study is a tool that allows for the analysis of muscle activity at various mouth-opening levels in a way that has not been previously explored in the literature. Full article

Background: Cannabidiol (CBD) has demonstrated potential as a therapeutic agent for muscle tension, pain, and sleep bruxism, yet its broader impact on comorbid conditions such as sleep disturbance and migraine disability remains underexplored. This study aimed to assess the effects of topical CBD on sleep quality and migraine-related disability in patients with bruxism-associated muscular pain. Methods: In a randomized, double-blind clinical trial, 60 participants with bruxism were allocated equally into three groups: control (placebo gel), 5% CBD gel, and 10% CBD gel. Participants applied the gel intraorally to the masseter muscles nightly for 30 days. Sleep quality and migraine-related disability were assessed using the Pittsburgh Sleep Quality Index (PSQI) and the Migraine Disability Assessment Scale (MIDAS), respectively. Surface electromyography (sEMG) and the Bruxoff^® device were used for objective evaluation of muscle tension and bruxism intensity. Results: Both CBD treatment groups demonstrated statistically significant improvements in PSQI and MIDAS scores compared to the control group (p < 0.001). No significant differences were observed between the 5% and 10% CBD groups, suggesting comparable efficacy. The sEMG findings corroborated a reduction in muscle tension. Improvements in sleep and migraine outcomes were positively correlated with reductions in muscle activity and pain. Conclusions: Topical CBD gel significantly improved sleep quality and reduced migraine-related disability in patients with bruxism-associated muscular pain, supporting its role as a multifaceted therapeutic option in the management of TMD and related comorbidities. Further research is needed to confirm long-term benefits and determine optimal dosing strategies. Full article

Background: Surface electromyography (sEMG) enables the non-invasive assessment of muscle activity and is widely used in orthodontics for evaluating masticatory muscles. However, little is known about the dynamic changes in facial expression muscles during orthodontic treatment. This study aimed to investigate alterations in facial muscle tone during the leveling and alignment phase in adult female patients undergoing fixed appliance therapy. Methods: The study included 30 female patients aged 20–31 years who underwent sEMG assessment at four time points: before treatment initiation (T0), at the start of appliance placement (T1), three months into treatment (T2), and six months into treatment (T3). Muscle activity was recorded during four standardized facial expressions: eye closure, nasal strain, broad smile, and lip protrusion. Electrodes were placed on the orbicularis oris, orbicularis oculi, zygomaticus major, and levator labii superioris alaeque nasi muscles. A total of 1440 measurements were analyzed using Friedman and Conover-Inman tests (α = 0.05). Results: Significant changes in muscle tone were observed during treatment. During lip protrusion, the orbicularis oris and zygomaticus major showed significant increases in peak and minimum activity (p < 0.01). Eye closure was associated with altered orbicularis oris activation bilaterally at T3 (p < 0.01). Nasal strain induced significant changes in zygomaticus and levator labii muscle tone, particularly on the right side (p < 0.05). No significant changes were noted during broad smiling. Conclusions: Orthodontic leveling and alignment influence the activity of selected facial expression muscles, demonstrating a dynamic neuromuscular adaptation during treatment. These findings highlight the importance of considering soft tissue responses in orthodontic biomechanics and suggest potential implications for facial esthetics and muscle function monitoring. Full article

Background and Objective: This study aimed to examine the possibility of using surface electromyography (sEMG) to aid in assessing the correctness of overhead deep squat performance. Electromyography signals were recorded for 20 athletes from the lower (rectus femoris (RF), vastus medialis (VM), biceps femoris (BF), and gluteus (GM)) and upper (deltoid (D), latissimus dorsi (L)) muscles. The sEMG signals were categorized into three groups based on physiotherapists’ evaluations of deep squat correctness. Methods: The raw sEMG signals were filtering at 10–250 Hz, and then the mean frequency, median frequency, and kurtosis were calculated. Next, the maximum excitation of the muscles expressed in percentage of maximum voluntary contraction (%MVC) and co-activation index (CAI) were estimated. To determine the muscle excitation level, the pulse interference filter and variance analysis of the sEMG signal derivative were applied. Next, analysis of variance (ANOVA) tests, that is, nonparametric Kruskal–Wallis and post hoc tests, were performed. Results: The parameter that most clearly differentiated the groups considered turned out to be %MVC. The statistically significant difference with a large effect size in the excitation of RF & GM (p = 0.0011) and VM & GM (p = 0.0002) in group 3, where the correctness of deep squat execution was the highest and ranged from 85% to 92%, was pointed out. With the decrease in the correctness of deep squat performance, an additional statistically significant difference appeared in the excitation of RF & BF and VM & BF for both groups 2 and 1, which was not present in group 3. However, in group 2, with the correctness of the deep squat execution at 62–77%, the statistically significant differences in muscle excitation found in group 3 were preserved, in contrast to group 1, with the lowest 23–54% correctness of the deep squat execution, where the statistical significance of these differences was not confirmed. Conclusions: The results indicate that sEMG can differentiate muscle activity and provide additional information for physiotherapists when assessing the correctness of deep squat performance. The proposed analysis can be used to evaluate the correctness of physical exercises when physiotherapist access is limited. Full article

The aim of this study was to analyze the activation of selected upper limb muscles. For the purposes of this article, we present results concerning the following muscles: triceps brachii, anterior and posterior deltoid, and trapezius in women aged 50 and above during simulated riding of the Torqway device, using surface electromyography (sEMG). The primary objective was to compare muscle activity across two movement phases: active and passive. Accordingly, the following research hypotheses were formulated: muscle activity (measured by RMS values) will be significantly higher during the active phase compared to the passive phase, and MPF (mean power frequency) values will decrease over time, indicating the onset of muscle fatigue. Additionally, the potential of surface electromyography was assessed as a diagnostic tool for evaluating ergonomics and muscle effort in the context of designing personalized mobility devices for older adults. As the study of the Torqway device represents a pioneering research effort, this publication makes a significant contribution to the biomechanical analysis of new forms of active mobility supported by wearable sensor technologies. Full article

Core stability is fundamental to posture, balance, and force transmission throughout the kinetic chain. Although traditionally associated with athletic performance, emerging research highlights its broader applicability to recreational fitness. This study investigates the effects of an eight-week core training program on muscle hypertrophy, static balance, and neuromuscular control in recreationally active, non-athletic adults. Participants will undertake a structured intervention comprising progressive triads targeting core stability, strength, and power. Assessment methods include surface electromyography (EMG), ultrasound imaging, three-dimensional force plates, Kinovea motion analysis, and the Satisfaction With Life Scale (SWLS) questionnaire. Expected outcomes include enhanced core muscle activation, improved static balance, and increased core-generated force during overhead medicine ball slam trials. Additionally, the intervention aims to facilitate hypertrophy of the transverse abdominis, internal oblique, and lumbar multifidus muscles, contributing to spinal resilience and motor control. This protocol bridges gaps in core training methodologies and advances their scalability for recreational populations. The proposed model offers a structured, evidence-informed framework for improving core activation, postural stability, muscle adaptation, movement efficiency, and perceived quality of life in recreationally active individuals. Full article

Hydrogels have immense potential in soft electronics due to their similarity to biological tissues. However, for applications in fields like tissue engineering and wearable electronics, hydrogels must obtain electrical conductivity, stretchability, and implantability. This article explores recent advancements in the development of electrically conductive hydrogel composites with high conductivity, low Young’s modulus, and remarkable stretchability. By incorporating conductive particles into hydrogels, such as poly(3,4-ethylenedioxythiophene)/poly (styrenesulfonate) (PEDOT/PSS) researchers have enhanced their conductivity. This study presents a one-pot synthesis method for creating electrically conductive hydrogel composites by combining PEDOT/PSS with alginate. The hydrogel reveals changes in chemical composition upon treatment with dimethyl sulfoxide (DMSO). Additionally, surface morphology analysis via Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM) demonstrate the impact of DMSO treatment on PEDOT/PSS/alginate films. Furthermore, electrical conductivity measurements highlighted the effectiveness of the conductive hydrogels in Electromyography (EMG) and human motion detection. This study offers insights into the fabrication and characterization of stretchable, conductive hydrogels, advancing their potential for various soft sensing biomedical applications. The optimized PDOT/PSS/alginate composite under dry condition shows a conductivity of 0.098 S/cm and can be stretched without significant loss in conductivity or mechanical stability. This one-pot method provides a simple and effective way to improve the properties of conductive hydrogel-based sensors. Full article

Surface electromyography (sEMG) signals are commonly employed for dynamic-gesture recognition. However, their robustness is often compromised by individual variability and sensor placement inconsistencies, limiting their reliability in complex and unconstrained scenarios. In contrast, strain-gauge signals offer enhanced environmental adaptability by stably capturing joint deformation processes. To address the challenges posed by the multi-channel, temporal, and amplitude-varying nature of strain signals, this paper proposes a lightweight hybrid attention network, termed MACLiteNet. The network integrates a local temporal modeling branch, a multi-scale fusion module, and a channel reconstruction mechanism to jointly capture local dynamic transitions and inter-channel structural correlations. Experimental evaluations conducted on both a self-collected strain-gauge dataset and the public sEMG benchmark NinaPro DB1 demonstrate that MACLiteNet achieves recognition accuracies of 99.71% and 98.45%, respectively, with only 0.22M parameters and a computational cost as low as 0.10 GFLOPs. Extensive experimental results demonstrate that the proposed method achieves superior performance in terms of accuracy, efficiency, and cross-modal generalization, offering a promising solution for building efficient and reliable strain-driven interactive systems. Full article

Muscle activity during exercise is typically assessed using oximeters, to evaluate local oxygen saturation (SmO₂), or surface electromyography (sEMG), to analyze electrical activation. Despite the importance of combining these analyses, no study has evaluated both of them during specific swimming exercises in combination with mechanical power output. This study aimed to assess muscle activity during an incremental test on a swim-bench utilizing oximeters and sEMG. Nine male swimmers performed a five-steps test: PRE (3 min at rest), STEP 1, 2, and 3 (swimming at a frequency of 25, 30, and 40 cycle/min for a duration of 2, 2, and 1 min, respectively), and POST (5 min at rest). Each swimmer wore two oximeters and sEMG, one for each triceps brachii. Stroke frequency and arm mechanical power (from ~13 to ~52 watts) estimated by the swim-bench were different among all steps, while no differences between arms were found. SmO₂ (from ~70% to ~60%) and sEMG signals (from ~20 to ~65% in signal amplitude) showed a significant increase among all steps. In both arms, a large/very large correlation was found between mechanical power and SmO₂ (r < −0.634), mechanical power and sEMG onset/amplitude (r > 0.581), and SmO₂ and sEMG amplitude (r > 0.508). No correlations were found between the slope of the sEMG spectral indexes and the slope of SmO₂; only sEMG detected electrical manifestation of muscle fatigue through the steps (p < 0.05). Increased muscle activity, assessed by both oximeters and sEMG, was found at mechanical power increases, revealing both devices can detect effort variation during exercise. However, only sEMG seems to detect peripheral manifestations of fatigue in dynamic conditions. Full article

Electroencephalography (EEG) and surface electromyography (sEMG) signals are widely used in human–machine interaction (HMI) systems due to their non-invasive acquisition and real-time responsiveness, particularly in neurorehabilitation and prosthetic control. However, existing deep learning approaches often struggle to capture both fine-grained local patterns and long-range spatio-temporal dependencies within these signals, which limits classification performance. To address these challenges, we propose a lightweight deep learning framework that integrates adaptive spatial attention with multi-scale temporal feature extraction for end-to-end EEG and sEMG signal decoding. The architecture includes two core components: (1) an adaptive attention mechanism that dynamically reweights multi-channel time-series features based on spatial relevance, and (2) a multi-scale convolutional module that captures diverse temporal patterns through parallel convolutional filters. The proposed method achieves classification accuracies of 79.47% on the BCI-IV 2a EEG dataset (9 subjects, 22 channels) for motor intent decoding and 85.87% on the NinaPro DB2 sEMG dataset (40 subjects, 12 channels) for gesture recognition. Ablation studies confirm the effectiveness of each module, while comparative evaluations demonstrate that the proposed framework outperforms existing state-of-the-art methods across all tested scenarios. Together, these results demonstrate that our model not only achieves strong performance but also maintains a lightweight and resource-efficient design for EEG and sEMG decoding. Full article

Background/Objectives: The objective of this study was to compare muscular strength and neuromuscular activation characteristics between male gymnasts and physical education (PE) students during isometric shoulder extension and flexion tasks. Methods: Thirteen competitive male gymnasts (age: 19.59 ± 1.90 years; body mass: 66.54 ± 6.10 kg; height: 169.38 ± 6.28 cm; mean ± SD) and thirteen male physical education (PE) students (age: 20.96 ± 2.30 years; body mass: 74.00 ± 8.69 kg; height: 174.96 ± 4.93 cm) voluntarily participated in the study. Peak torque (PT), rate of torque development (RTD), RTD normalized to body mass (RTD/BM), and muscle activation assessed via surface electromyography (EMG), normalized to maximal EMG activity (EMG/EMGmax), were evaluated during bilateral isometric shoulder extension and flexion at a joint angle of 45°. Measurements were analyzed across the following time intervals: −50 to 0 ms (pre-tension), 0–30 ms, 0–50 ms, 0–100 ms, and 0–200 ms relative to contraction onset. Custom MATLAB R2024b scripts were used for data processing and visualization. One-way and two-way multivariate analyses of variance (MANOVAs) were conducted to test for group differences. Results: Gymnasts exhibit higher values of PT, PT/BM, RTD, and RTD/BM particularly within the early contraction phases (i.e., 0–50 ms and 0–100 ms) compared to PE students (p < 0.05 to <0.001; η² = 0.04–0.66). Additionally, EMG activity normalized to maximal activation (EMG/EMGmax) was significantly greater in gymnasts during both early and mid-to-late contraction phases (0–100 ms and 0–200 ms), (p < 0.05 to <0.001; η² = 0.04–0.48). Conclusions: These findings highlight gymnasts’ superior explosive neuromuscular capacity. Metrics like RTD, RTD/BM, and EMG offer valuable insights into rapid force production and neural activation, supporting performance monitoring, training optimization, and injury prevention across both athletic and general populations. Full article

Flexed and tensed arm (FTA) circumference is a fundamental anthropometric measurement for determining the mesomorphic component in somatotype. This study examined the impact of contralateral limb opposition (+OP) on arm circumference measurement and biceps brachii muscle activation. Fifty physically active men and women, mean (22.7 ± 2.9 years), participated in this study. FTA circumference measurements were taken with FTA + OP and without opposition FTA, following ISAK protocols. Additionally, biceps brachii muscle activation was assessed using surface electromyography (sEMG). Significant differences were identified in the flexed and tensed arm circumference (>1%) and in the mesomorphic component between the FTA and FTA + OP conditions (p < 0.001). In addition, contralateral limb opposition resulted in a significant average increase of 39.02% in biceps brachii muscle activation, with variations between 24.57% to 47.46% across the time intervals analyzed (p < 0.05). A moderate correlation was observed between the percentage difference in sEMG and arm circumference during the middle second of contraction (r = 0.418). However, during the first (r = 0.393), third (r = 0.376), and mean (r = 0.385) contraction periods, the correlation was considered weak. Contralateral limb opposition caused greater biceps brachii muscle activation, resulting in an increase in flexed and tensed arm circumference in physically active young adults. Full article

Objective: This study aims to investigate the effect of shot selection on the muscle coordination characteristics during basketball shooting. Methods: A three-dimensional motion capture system, force platform, and wireless surface electromyography (sEMG) were used to simultaneously collect shooting data from 14 elite basketball players. An inverse mapping model of sEMG signals and spinal α-motor neuron pool activity was developed based on the Debra muscle segment distribution theory. Non-negative matrix factorization (NMF) and K-means clustering were used to extract muscle coordination features. Results: (1) Significant differences in spinal segment activation timing and amplitude were observed between stationary and jump shots at different distances. In close-range stationary shots, the C5-S3 segments showed higher activation during the TP phase and lower activation during the RP phase. For mid-range shots, the C6-S3 segments exhibited greater activation during the TP phase. In long-range shots, the C7-S3 segments showed higher activation during the TP phase, whereas the L3-S3 segments showed lower activation during the RP phase (p < 0.01). (2) The spatiotemporal structure of muscle coordination modules differed significantly between stationary and jump shots. In terms of spatiotemporal structure, the second and third coordination groups showed stronger activation during the RP phase (p < 0.01). Significant differences in muscle activation levels were also observed between the coordination modules within each group in the spatial structure. Conclusion: Shot selection plays a significant role in shaping neuromuscular control strategies during basketball shooting. Targeted training should focus on addressing the athlete’s specific shooting weaknesses. For stationary shots, the emphasis should be on enhancing lower limb stability, while for jump shots, attention should be directed toward improving core stability and upper limb coordination. Full article

Manual wheelchair users are at high risk of upper limb overuse injuries due to repetitive propulsion mechanics. To address this, we developed a novel detachable push–pull dual-propulsion device that enables both forward and backward propulsion, aiming to reduce shoulder strain and promote balanced muscle engagement. This study presents a protocol to evaluate the device’s biomechanical impact and ergonomic effects, focusing on objective, quantitative analysis using a repeated-measures within-subject design. Thirty participants with spinal cord injury will perform standardized propulsion trials under two conditions: push and pull. Motion capture and surface electromyography (EMG) will assess upper limb kinematics and muscle activation. Each propulsion mode will be repeated over a 10-m track, and maximum voluntary contraction (MVC) data will be collected for EMG normalization. The protocol aims to provide objective evidence on the propulsion efficiency, muscle distribution, and ergonomic safety of the device. Findings will inform future assistive technology development and rehabilitation guidelines for manual wheelchair users. Full article