Electromyographic Data Research Articles

Effect of foot strike patterns and angles on the biomechanics of side-step cutting

ObjectivesThe study aimed to determine how foot strike patterns and cutting angles affect lower extremity (LE) kinematics, kinetics, and muscle activity during side-step cutting.MethodsTwenty male college sport athletes participated in this research. Three-dimensional motion analysis featuring ground reaction force (GRF) and electromyography (EMG) of the dominant leg was used. LE kinematics, kinetics, and EMG data parameters were obtained during a 45° and 90° side-step cutting involving rearfoot strikes (RFS) and forefoot strikes (FFS).ResultsThe significant foot strike pattern × angle interactions were observed for the ankle eversion range of motion (ROM) at the loading phase. Cutting of 90° had greater knee flexion ROM, knee valgus ROM, and knee varus moment compared to that of 45°. RFS cutting had greater knee flexion, hip flexion, knee valgus, knee varus moment, knee varus moment, and ankle eversion ROM. FFS cutting produced a lower vertical GRF, lateral GRF, and a loading rate. Both vastus medialis and vastus lateralis muscle activities were remarkably greater during cutting of 90° than 45°. At the loading phase, semitendinosus, biceps femoris, and the lateral head of gastrocnemius muscle activities during FFS cutting were considerably greater than those during RFS cutting.ConclusionThe FFS pattern can better protect the anterior cruciate ligament (ACL) and improve the flexibility of athletes by increasing the plantarflexion torque of the ankle. The injury risk also increases with the larger cutting angle. The EMG activities of semitendinosus and biceps femoris are vital for the stability of knee joint during side-step cutting, which helps reduce ACL stress during buffering.

Assessment of trunk and shoulder muscle asymmetries during two-armed kettlebell swings: implications for training optimization and injury prevention

IntroductionGreater side-to-side asymmetry can indicate impaired skill, reduced power production, and an increased risk of injury. Bilateral differences highlight the presence of asymmetries that should be assessed to understand their impact on both injury risk and performance enhancement.ObjectiveThis study aimed to assessment muscle activation and bilateral asymmetry in major trunk and shoulder muscles during a two-armed kettlebell swing exercise.MethodsTwenty-seven participants (age: 24.2 ± 2.6 years; body mass: 82.9 ± 7.7 kg; height: 176.9 ± 7.0 cm) were included in the study. Electromyographic (EMG) data were collected bilaterally from twelve muscles (six muscles per side: anterior deltoid [AD], posterior deltoid [PD], erector spinae longissimus [ESL], erector spinae iliocostalis [ESI], external oblique [EO], and rectus abdominis [RA]).ResultsResults indicated that asymmetry indices for the AD, ESL, ESI, and RA muscles during the upward propulsion phase fell within the determined threshold of 15%. However, the asymmetry indices for the PD and EO muscles exceeded this threshold by 3.36% and 2.62%, respectively. The findings suggest that trunk muscle asymmetries during the kettlebell swing are generally less pronounced than those of the shoulder muscles, particularly during the float phase.ConclusionThese results provide valuable insights into bilateral muscle asymmetry during a two-armed kettlebell swing, which can inform the development of targeted training programs. The methods and findings of this study may further contribute to understanding the effects of muscle balance, symmetry, and injury mechanisms in dynamic movements.

An Assist-as-Needed Control Strategy Based on a Subjective Intention Decline Model

In the rehabilitation training process for stroke patients, the level of excitement in the patient’s physiological state has a positive impact on the efficacy of the training. In order to improve patients’ initiative during training and prevent dependence on assistive systems, this study proposes an assist-as-needed control strategy based on a subjective intention decline model. The strategy primarily consists of two modules: a subjective intention decline control module and a limb movement assessment module. The subjective intention decline module collects surface electromyography (sEMG) data during patient training and optimizes support vector machine (SVM) using quantum particle swarm optimization (QPSO) algorithms to establish a subjective intention decline model. The limb movement assessment module collects information such as interaction force and position error during training and proposes a method for evaluating the motion state of the affected limb. This model combines traditional impedance control with a method for assessing limb movement and subjective status, automatically adjusting the level of assistive force on the affected limb in real time to enhance its active participation in tasks. Finally, we performed two verification experiments to assess the patient’s initiative in participating in the training. The experimental results show that the proposed method effectively reduced the average assist force by 65.66% for the traditional impedance control training system and effectively the average assist force by 35.2% for the control training system using only the assist force module based on force position information. At the same time, the accuracy of the subjective intention attenuation module established in the experiment to identify the fatigue level of the subjects reached 93.41%. Therefore, the proposed method effectively improves the initiative of trainers and also prevents patients from relying on the assist-as-needed control training system.

Comparison of synergy extrapolation and static optimization for estimating multiple unmeasured muscle activations during walking

BackgroundCalibrated electromyography (EMG)-driven musculoskeletal models can provide insight into internal quantities (e.g., muscle forces) that are difficult or impossible to measure experimentally. However, the need for EMG data from all involved muscles presents a significant barrier to the widespread application of EMG-driven modeling methods. Synergy extrapolation (SynX) is a computational method that can estimate a single missing EMG signal with reasonable accuracy during the EMG-driven model calibration process, yet its performance in estimating a larger number of missing EMG signals remains unknown.MethodsThis study assessed the accuracy with which SynX can use eight measured EMG signals to estimate muscle activations and forces associated with eight missing EMG signals in the same leg during walking while simultaneously performing EMG-driven model calibration. Experimental gait data collected from two individuals post-stroke, including 16 channels of EMG data per leg, were used to calibrate an EMG-driven musculoskeletal model, providing “gold standard” muscle activations and forces for evaluation purposes. SynX was then used to predict the muscle activations and forces associated with the eight missing EMG signals while simultaneously calibrating EMG-driven model parameter values. Due to its widespread use, static optimization (SO) applied to a scaled generic musculoskeletal model was also utilized to estimate the same muscle activations and forces. Estimation accuracy for SynX and SO was evaluated using root mean square errors (RMSE) to quantify amplitude errors and correlation coefficient r values to quantify shape similarity, each calculated with respect to “gold standard” muscle activations and forces.ResultsOn average, compared to SO, SynX with simultaneous model calibration produced significantly more accurate amplitude and shape estimates for unmeasured muscle activations (RMSE 0.08 vs. 0.15, r value 0.55 vs. 0.12) and forces (RMSE 101.3 N vs. 174.4 N, r value 0.53 vs. 0.07). SynX yielded calibrated Hill-type muscle–tendon model parameter values for all muscles and activation dynamics model parameter values for measured muscles that were similar to “gold standard” calibrated model parameter values.ConclusionsThese findings suggest that SynX could make it possible to calibrate EMG-driven musculoskeletal models for all important lower-extremity muscles with as few as eight carefully chosen EMG signals and eventually contribute to the design of personalized rehabilitation and surgical interventions for mobility impairments.

Correlations Between Mandibular Kinematics and Electromyography During the Masticatory Cycle: An Observational Study by Digital Analysis

The analysis of the masticatory cycle plays a fundamental role in studying the functions of the stomatognathic system and evaluating temporomandibular dysfunctions (TMD). The primary objective of this study is to investigate the complex interplay between mandibular kinematics and surface electromyography (sEMG) activity during the masticatory cycle using advanced 4D dentistry technology in 22 healthy subjects (without TMD). By employing electromyography, it becomes feasible to capture the electrical activity of the masticatory muscles throughout the chewing process. The BTS TMJOINT (© 2023 BTS Bioengineering, Garbagnate Milanese, MI, Italy) electromyograph was utilized in this study. Mandibular tracking, on the other hand, allows for recording the movements of the mandible during chewing and condylar slopes. This latest technology (ModJaw®, Tech in motion™, Villeurbanne, France) utilizes motion sensors placed on the jaw to accurately track three-dimensional movements, including jaw opening, closing, and lateral movements. Nowadays, in clinical gnathology, it is common practice to examine masticatory function by analyzing mandibular kinematics and muscle contraction as distinct entities. Similarly, the results obtained from these analyses are typically assessed independently. The investigation of a correlation between electromyography data and mandibular kinematics during the masticatory cycle could provide several advantages for clinicians in diagnosis and lead to a combined analysis of muscle activities and intraarticular dynamics. In conclusion, it can be inferred from the results obtained in the present study that the chewing cycle with a greater vertical movement results in increased masseter muscular activity, and condylar slopes are positively correlated to an increase in temporalis muscle activation. This comprehensive approach can provide valuable insights into the relationship between muscle activity and mandibular movement, enabling clinicians to gain a deeper understanding of the functional dynamics of the stomatognathic system.

Use of machine learning methods in diagnosis of carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is a common condition diagnosed using physical exams and electromyography (EMG) data. This study aimed to classify CTS severity using machine learning techniques. EMG data from 154 patients, including measurements of motor and sensory latency, velocity, and amplitude, were used to form a six-dimensional feature space. Classifiers such as DT, LDA, NB, SVM, k-NN, and ANN were applied, and the feature space was reduced using ANOVA, MRMR, Relieff, and PCA. The DT classifier with ANOVA feature selection showed the best performance for both full and reduced feature spaces.

Research on the association mechanism and evaluation model between EMG data and product aesthetic quality in product aesthetics evaluation

Product aesthetics play a crucial role in user satisfaction and product success. However, the feasibility and accuracy of using electromyographic (EMG) data for product aesthetic quality evaluation are unknown. Here, we analysed the correlations and associations between EMG physiological data and product aesthetic quality of 60 subjects by SPSS software and designed a product aesthetic quality evaluation model based on the multivariate logistic (M) algorithm to answer this question. It was found that the EMG data of the zygomatic and buccal muscles did not have significant correlations with product aesthetic quality, whereas five indicators in the EMG data of the frowning muscles had significant correlations relationships with product aesthetic quality. We also found that the overall accuracy of the product aesthetic quality evaluation model was 72.3%, which was able to better distinguish product aesthetic quality. This study demonstrates that product aesthetic quality can be evaluated using EMG data and that the product aesthetic quality evaluation model can provide an objective and accurate decision-making reference to help engineers and designers in product aesthetic quality evaluation and product design. This study lays the foundation for the future integrated multimodal physiology to conduct aesthetics quality evaluations with a high degree of accuracy.

The effect of squats on muscle activity in standing, kneeling, and half-kneeling positions: A cross-sectional study.

Kneeling and half-kneeling training are common positions used in physical therapy. however, research on lower extremity muscle activity is lacking compared to the ergonomic aspects and trunk muscle activity. The purpose of this study is to investigate the effects on lower extremity muscle activity during squats in kneeling and half-kneeling positions. The study was designed as a cross-sectional study with a single group of healthy adults. Participants were instructed to perform squats while assuming 3 positions (standing, kneeling, and half-kneeling). Surface electromyography data were recorded 3 times from the rectus femoris (RF), gluteus maximus (GMax), gluteus medius (GMed), and biceps femoris (BF) on the participant's dominant side, and the mean values were analyzed. The participants performed squats for 9 seconds, with 4 seconds of the descent phase, 1 second of the maintenance phase, and 4 seconds of the ascent phase. A metronome was used to ensure precise timing. The study included 30 participants (19 males and 11 females). The muscle activities of the RF, GMed, and BF showed statistically significant differences among the 3 positions, being highest in the half-kneeling position (HKP), followed by the standing position (SP) and kneeling position (KP). The muscle activity of the GMax was significantly higher in the HKP than in the SP and KP (P < .05). The co-contraction ratio was significantly higher with KP than with the SP and HKP (P < .05). In the SP and KP, there were statistically significant differences between the ascent and descent phases of the RF, GMax, GMed, and BF (P < .05). In the HKP, there were statistically significant differences between the ascent and descent phases of the RF, GMax, and GMed (P < .05). The results of this study indicate that squats in the HKP (especially during the ascent phase) require the highest muscle activity, whereas squats in the KP (especially during the descent phase) can be performed with the lowest muscle activity. It can be concluded that these findings could serve as selective indicators for squat exercises and in enhancing postural control, muscle strength, and lower extremity stabilization.

Differences in Emotion Expression, Suppression, and Cardiovascular Consequences Between Black and White Americans in the Midlife in the United States (MIDUS) Study.

Recent theoretical work suggests the expression of emotions may differ among Black and White Americans, such that Black Americans engage more frequently in expressive suppression to regulate emotions and avoid conflict. Prior work has linked expressive suppression usage with increases in cardiovascular disease risk, suggesting that racialized differences in expressive suppression usage may be one mechanism by which racism "gets under the skin" and creates heath disparities. To examine racialized differences in expressive suppression and blood pressure (a measure of cardiovascular disease risk), we used self-report and facial electromyography (fEMG) data from two cohorts of Black and White Americans from the Midlife in the United States (MIDUS) longitudinal study (MIDUS 2, n = 271, 34.7% Black, collected from 2004-2009; MIDUS Refresher 1, n = 114, 31.6% Black, collected from 2012-2016; total N = 385, 33.9% Black). Black Americans reported engaging in expressive suppression more frequently than White Americans (t(260.95) = 2.18, p = .002) and showed less corrugator fEMG activity during negative images(t(969) = 2.38, pFDR = .026). Less corrugator activity during negative images was associated with higher systolic blood pressure only for Black Americans (b = -4.63, t(375) = 2.67, p = .008). Overall, results are consistent with theoretical accounts that Black Americans engage more frequently in expressive suppression, which in turn is related to higher cardiovascular risk. Additional research is needed to further test this claim, particularly in real-world contexts and self-reports of in-the-moment usage of expressive suppression.

Shoulder-assist exoskeleton effects on balance and muscle activity during a block-laying task on a simulated mast climber

Interest in utilizing exoskeletons to mitigate the risks of musculoskeletal disorders (MSDs) among construction workers is growing, spurred by encouraging results in other industries. However, it is crucial to carefully examine their impact on workers' stability and balance before implementation. In this study, seven male participants lifted a 35-lb cinder block from a production table to a simulated wall at two heights—elbow and shoulder levels—using three different exoskeleton models on an unstable platform, where their balance and shoulder muscle activity were assessed. Balance-related parameters, included mean distance (MDIST), total excursion (EXCUR), and mean velocity (VEL) of the center of pressure, were derived from force plate data. Muscle activity in six shoulder and upper arm muscles was estimated using electromyography (EMG) data. The results indicated that wearing two of the exoskeletons significantly increased both total and medio-lateral (ML) MDIST compared to not wearing an exoskeleton. Wearing one of the exoskeletons significantly increased total and ML VEL and ML EXCUR. Although lifting level did not have a significant impact on the balance parameters, it did affect the muscle activity in most of the measured muscles. Moreover, only one exoskeleton significantly reduced the activity in a particular shoulder muscle compared to no exoskeleton use. In conclusion, the evaluated shoulder-assist exoskeletons showed limited benefits for preventing upper extremity MSDs and may negatively affect whole-body balance during a block-laying task on an unstable platform. These findings underscore the importance of comprehensive evaluations of balance and effectiveness prior to adopting exoskeletons in construction.

The human lower leg muscle pump functions as a flow diverter pump, maintaining low ambulatory venous pressures during locomotion

ObjectiveAmbulatory venous pressure (AVP) is the drop of pressure observed in the superficial veins of the lower leg during movement. This phenomenon has been linked to the function of the calf muscle pump (CMP) and the competence of venous valves. Nevertheless, the concept of the CMP function remains controversial. This study aimed to elucidate the association between lower leg muscles activity, changes in pressure in distinct venous segments, and lower extremity arterial blood supply in healthy subjects during various types and intensities of exercise. MethodsTwelve legs of nine healthy volunteers were enrolled in the study. Continuous pressure (intramuscular vein [IV] and three great saphenous vein [GSV] points) and surface electromyography data (gastrocnemius and anterior tibial [ATM] muscles) were recorded during treadmill walking, running, and plantar flexion exercises. The pressure gradient (ΔP, mmHg) between adjacent points of measurement was calculated. Minute unit power of muscle pump ejection and suction (NE, and NS, MPa/min) were calculated and compared with the arterial blood supply of the lower extremity (LBF, L/min). ResultsΔP demonstrated a consistent pattern of changes during walking and running. In GSV, the ΔP was observed to be directed from the thigh to the mid-calf (retrogradely) and from the ankle to the mid-calf (anterogradely) throughout the entire stride cycle. However, its value decreased with increasing stride cycle frequency. The dynamics of ΔP between the IV and GSV were as follows: It was directed from the IV to GSV during gastrocnemius contraction and was reversed during anterior tibial muscle contraction and gastrocnemius relaxation (swing phase). LBF, NE, and NS demonstrated similar exponential growth with increasing stride frequency during walking and running. ConclusionsDuring natural locomotion, the muscle pump acts as a flow diverter pump, redirecting the flow of blood from the superficial veins to the intramuscular veins via the perforating veins. During ambulation, the pressure in the superficial venous network depends upon the capacity of the muscle pump to provide output that matches the changes in arterial blood flow.

Is essential tremor a risk factor for carpal tunnel syndrome? A prospective study excluding the most common comorbid conditions

Aims: Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy of the upper extremity, resulting from compression of the median nerve. Tremor, a rhythmic and involuntary movement of any part of the body, is the most common movement disorder, affecting millions of people worldwide. There is limited research on the coexistence of CTS and ET (essential tremor). Methods: This prospective study included patients aged 18-65 who presented to the neurology outpatient clinic and were diagnosed with ET. Participants supplied informed consent, a sociodemographic form, and the Fahn-Tolosa-Marin Clinical Tremor Rating Scale (FTM TRS). Patients were evaluated for the presence and severity of CTS with electromyography (EMG). The EMG data were categorized as normal, mild, moderate, and severe CTS. Results: In the study, the average age of the 50 ET patients was 56.0 (35.0-64.0) years. The gender distribution comprised 22 (44.0%) males and 28 (56.0%) females. The following tremor locations were reported: 41 (82.0%) in both upper extremities, 3 (6.0%) in the right upper extremity, 2 (4.0%) in the left upper extremity, 1 (2.0%) in both upper extremities, head tremor, and voice, and 3 (6.0%) in both upper extremities and head tremor. A high prevalence of CTS was detected in ET patients (46%). Additionally, a positive correlation was found between CTS in ET patients, long disease duration, and female gender. No significant relationship was found between FTM TRS Part A, Part B, Part C, total scores, and median sensory and motor nerve amplitude and velocity values in ETS patients. Conclusion: CTS is more common in patients with ET. This suggests that ET may be a risk factor for CTS, independent of other factors. Early diagnosis and treatment of CTS in patients with ET is important to improve their quality of life.

Construction and validation of a nomogram model for predicting different sites of ankle pain in runners with chronic ankle instability

This study aimed to establish a risk prediction nomogram model for anterolateral, mediolateral, and posterolateral ankle pain in runners with chronic ankle instability (CAI) and analyse the potential risk factors for pain at different ankle sites. Thirty recreational runners with CAI who reported ankle pain in the anterolateral, mediolateral, or posterolateral regions were recruited for this study. Kinematic, kinetic, and electromyographic data during running were collected using motion capture system, 3-D force platform, and surface electromyography system. These data were used to generate a dynamic nomogram. The results showed that anterolateral ankle pain in runners with CAI may be caused by insufficient gastrocnemius muscle strength (OR 0.85, 95% CI 0.73–0.97), excessive ground reaction force (GRF, OR 2.64, 95% CI 1.25–6.22), and an increased percentage of ankle energy absorption (OR 9.11, 95% CI 1.50–77.79). Mediolateral ankle pain might be contributed by greater ankle inversion angle (OR 1.08, 95% CI 1.01–1.00) and GRF (OR 2.13, 95% CI 1.17–4.31). Moreover, posterolateral ankle pain was predicted by increased ankle adduction angle (OR 1.06, 95% CI 1.00–1.12), increased GRF (OR 2.16, 95% CI 1.07–4.80), and decreased dynamic stability (OR 0.20, 95% CI 0.05–0.68). To prevent ankle pain, runners with CAI should be encouraged to focus on improving the neuroreceptor sensitivity of the gastrocnemius muscles, and retraining their energy absorption patterns.

Mechanisms of gait speed changes in middle-aged adults: Simultaneous analysis of magnitude and temporal effects

BackgroundMiddle-aged adults represent the transition between younger and older adults, where some of the characteristic gait differences due to aging begins to surface. However, the gait characteristics of middle-aged adults across the whole gait cycle remains an understudied topic. As speed is a sensitive indicator of health, characterizing the effects of speed on the gait of middle-aged adults and differentiating it from the response of young adults will provide insights into the effects of aging on gait speed modulation mechanisms. Research questionWhat are the mechanisms of gait speed changes that are employed by middle-aged adults, and how are they different from younger adults? MethodsA cohort of healthy young and middle-aged adults completed 60 second trials at three different speeds. Joint kinematics, kinetics, and surface electromyography data were analyzed and compared between the speed levels and age groups. Statistical Parametric Mapping along with a nonlinear curve registration algorithm was used to simultaneously assess the changes in both magnitude and timing of different metrics. ResultsWhen compared to the younger cohort, the middle-aged cohort had significantly lower ankle range of motion, dorsiflexion moment during loading response and plantarflexion moment during push-off. At the knee joint, the middle-aged adults had significantly lower knee flexion moment during stance. At the hip joint, the middle-aged adults had lower extension moment during terminal stance. SignificanceTime-continuous analysis showed that primary differences due to age were related to decreased joint range of motion and joint moment production capability in the middle-aged adults. Faster walking appears a safe method for middle-aged adults to increase joint range of motion and joint moment expression. However, targeted interventions that focus on improving capability are likely also needed. Suggested targets being improving ankle and knee joint moment capability, and increased range of motion at all joints.

Data-Driven Stroke Classification Utilizing Electromyographic Muscle Features and Machine Learning Techniques

Background: Predicting a stroke in advance or through early detection of subtle prodromal symptoms is crucial for determining the prognosis of the remaining life. Electromyography (EMG) has the advantage of easy and quick collection of biological data in clinical settings; however, its application in data processing and utilization is somewhat limited. Thus, this study aims to verify how simple signal processing and feature extraction utilize EMG in machine learning (ML)-based prediction models. Methods: EMG data were collected from the legs of 120 healthy individuals and 120 stroke patients during gait. Four statistical features were extracted from 16 EMG signals and trained on seven ML-based models. The accuracy of the validation and test datasets was also examined. Results: The model with the best performance was Random Forest. Among the 16 EMG signals, the average and maximum values of the muscle activities involved in knee extension (i.e., vastus medialis and rectus femoris) contributed significantly to the predictions. Conclusion: The results of this study confirmed that the simple processing and feature extraction of EMG signals effectively contributed to the accuracy of ML-based models. Routine use of EMG data collected in clinical environments is expected to provide benefits in terms of stroke prevention and rehabilitation.

Effects of time-dependent acupuncture on back muscle endurance in women with chronic nonspecific low back pain: A randomized crossover trial.

Chronic nonspecific low back pain (CNLBP) is a leading cause of disability and remains a major burden for many public health systems. Acupuncture is a nonpharmacological treatment for CNLBP that can be effective in improving low back pain; nevertheless, its effect on improving back muscle endurance in patients with CNLBP and its duration of effect have not been studied. The goal of this study was to assess the impact of acupuncture on lower back muscle activity in CNLBP patients. This was a single-blind, randomized, crossover experimental study. Thirty female patients were randomized into Group A (15 patients) or Group B (15 patients). Patients in Group A were assigned to receive real acupuncture (RA) in the first phase and sham acupuncture (SA) in the second phase, while those in Group B received SA first and then RA, with a 1-week washout period between phases. Two-way repeated ANOVA was used to evaluate the effect of group and time on isokinetic parameters, Surface electromyography (sEMG) data, and blood data. Significant interaction effects were identified between group * time on the isokinetic parameters of the lumbar extensor muscles, sEMG values of the erector spinae, blood lactate levels, and blood ammonia levels (all p< 0.05). Compared with those of the SA group, the isokinetic parameters of the lumbar extensor muscles, sEMG values of the erector spinae, blood lactate levels, and blood ammonia levels of the RA group were significantly different (all p< 0.05). RA improves lumbar extensor endurance in patients with CNLBP and lasts approximately 9 minutes. RA can improve blood circulation to reduce blood lactic acid and blood ammonia produced during exercise.

Unveiling human biomechanics: insights into lower limb responses to disturbances that can trigger a fall.

Slip-related falls are a significant concern, particularly for vulnerable populations such as the elderly and individuals with gait disorders, necessitating effective preventive measures. This manuscript presents a biomechanical study of how the lower limbs react to perturbations that can trigger a slip-like fall, with the ultimate goal of identifying target specifications for developing a wearable robotic system for slip-like fall prevention. Our analysis provides a comprehensive understanding of the natural human biomechanical response to slip perturbations in both slipping and trailing legs, by innovatively collecting parameters from both the sagittal and frontal plane since both play pivotal roles in maintaining stability and preventing falls and thus provide new insights to fall prevention. We investigated various external factors, including gait speed, surface inclination, slipping foot, and perturbation intensity, while collecting diverse data sets encompassing kinematic, spatiotemporal parameters, electromyographic data, as well as torque, range of motion, rotations per minute, detection, and actuation times. The biomechanical response to slip-like perturbations by the hips, knees, and ankles of the slipping leg was characterized by extension, flexion, and plantarflexion moments, respectively. In the trailing leg, responses included hip flexion, knee extension, and ankle plantarflexion. Additionally, these responses were influenced by gait speed, surface inclination, and perturbation intensity. Our study identified target range of motion parameters of 85.19°, 106.34°, and 95.23° for the hips, knees, and ankles, respectively. Furthermore, rotations per minute values ranged from 17.85 to 51.10 for the hip, 21.73 to 63.80 for the knee, and 17.52 to 57.14 for the ankle joints. Finally, flexion/extension torque values were estimated as -3.05 to 3.22 Nm/kg for the hip, -1.70 to 2.34 Nm/kg for the knee, and -2.21 to 0.90 Nm/kg for the ankle joints. This study contributes valuable insights into the biomechanical aspects of slip-like fall prevention and informs the development of wearable robotic systems to enhance safety in vulnerable populations.

Digital Twin for Amputees: A Bidirectional Interaction Modeling and Prototype with Convolutional Neural Network

With over 2 million amputees in the U.S., they have been facing significant employment challenges. However, several physical prostheses still lack usability to be able for them to work in person. Therefore, this study explores an innovative application of digital twin approach, focusing on bidirectional interaction modeling and prototyping using convolutional neural networks (CNNs). We developed a simplified digital twin environment integrating electromyography (EMG) sensors and virtual reality (VR) to enable real-time interaction between the virtual and physical worlds. The CNN model, trained to classify hand movement from EMG data, achieved a test accuracy of 99%, demonstrating its effectiveness for practical applications. Our framework facilitates remote control of physical devices through VR gestures, potentially allowing amputees to perform meaningful work from home, thus overcoming physical limitations and fostering greater independence. This preliminary study underscores the possibility of digital twin technology to redefine workplace accessibility, offering amputees opportunities for potential employment.

Psychophysiological distinctions in emotional responding: sensitivity to perceiving loss of connection.

Emotion involves oneself in relation to a subject of attention; e.g., sadness is to be sad about something/someone. This study examined emotional responses to perceiving a loss of connection from oneself. Evidence suggests that Europeans tend to perceive salient objects in the foreground, while East Asians are more likely to perceive holistically, considering the interrelationships between the context and the object. We studied how this distinction affected European Americans' (EA) and Chinese Americans' (CA) sensitivity to perceiving the loss of connection. Both groups were exposed to loss by playing Cyberball, a ball-tossing video game, and then watched a film clip on grief. We hypothesized that EA would respond with increasing heart rate (HR) variance around the mean when perceiving loss. CA were predicted to show no difference from controls. We also hypothesized that EA would feel sadder, in terms of decreased HR and increased respiratory sinus arrhythmia (RSA), earlier during the film clip. In total, 53 subjects were recruited, of which 40 were EA (47.5% women, age 21.08 ± 1.94 years) and 13 were CA (61.5% women, age 21.05 ± 1.74 years); 25 subjects (19 EA, 6 CA) received 2 out of 48 balls tossed in Cyberball and the controls received 10. ECG, respiration, and facial electromyography (fEMG) data were acquired. The results during Cyberball showed that EA's HR variance relative to baseline (HR SDc/b) had an upward trend on perceiving loss. Contrary to prediction, CA also showed higher levels of HR variance relative to baseline. The ANOVA of HR SDc/b revealed that the interaction effect of two factors, time and condition, was statistically significant (p = 0.009). However, as predicted, EA in the experimental condition had decreased HR and increased RSA, a sign of withdrawal in sadness, 30 to 60 s into the sad clip. fEMG data at the corrugator muscle revealed that EA activated higher peak intensity 5.5 s earlier than CA (increased 1.571 vs. 0.844). This difference, however, was not statistically significant. The evidence suggests that increased exposure to loss automatically led to increased HR variance in both groups even when subjects were informed that players were computer-generated. However, the effect was stronger on EA to increase their arousal and sensitivity to grief thereafter.

Effects of victim's body posture and attacker's gender on slashing attacks: a biomechanical study.

Sharp force injury has been and will remain to be a major cause of violent death; however, scientific evaluations on the impact of body posture of the victim and gender of the perpetrator on sharp force injury have been scarce. The purpose of this study was to evaluate the biomechanical characteristics found in individuals (male and female) when using a Chinese kitchen knife to slash the neck of a dummy while it was in the standing and supine positions. This work offers a solid basis for forensic identifications, criminal investigations, and court trials. A total of 12 male and 12 female college students participated in this study. Kinematic, kinetic, and surface electromyography (sEMG) data were evaluated when slashing the neck of a dummy while it was in the standing and supine positions using a Chinese kitchen knife. When slashing the neck of a standing dummy, participants showed shorter contact time (19.5%) and slower shoulder velocities (30.9%) as well as higher hip velocity (26.0%) and increased root mean square (RMS) and integral electromyography (iEMG) for the anterior deltoid (51.3% and 51.2%, respectively) compared to those while the dummy was in the supine position (all p < 0.05), regardless of gender. When slashing a dummy's neck while it was in standing and supine positions, male participants showed higher shoulder, elbow, and wrist velocities (22.6%, 22.7%, and 24.4%, respectively) and higher slashing velocity (19.8%), slashing force (24.2%), and energy (46.2%) than female participants (all p < 0.05). In addition, male participants showed shorter contact time (17.8%), and the values of RMS and iEMG of the anterior deltoid, biceps brachii, extensor carpi radialis longus, and flexor carpi ulnaris were less than those of female participants (98.9%, 47.3%, 65.6%, and 33.4% for RMS and 115.1%, 59.4%, 80.1%, and 47.8% for iEMG, respectively). There was no difference in slashing speed, slashing force, and energy when using a Chinese kitchen knife to slash the dummy's neck while it was in different body postures (standing and supine), suggesting a similar level of injury severity. However, there were significant differences in slashing action patterns between the two body postures, with longer contact time, smaller hip velocity, greater shoulder velocity, and less muscle activation level of the deltoid exertion when slashing the dummy's neck in the supine position. Gender may have a greater effect on the severity of slashing, and the gender difference may be partly related to the body weight difference. The findings from this study may provide quantitative indicators and references for analyzing the motive behind the crime, as well as for case reconstruction, and for the court's conviction and sentencing processes.