Neuromuscular junction dysfunction in a subset of Charcot-Marie Tooth and related peripheral neuropathies mouse models.

Analysis of anticipatory postural adjustment characteristics in preschool children with different motor development profiles.

Relationship between forearm flexor-pronator muscles activity and medial elbow joint gapping distance during repetitive baseball pitching.

Brachiation-based movement as a theoretical framework for addressing technology-related postural dysfunction: An evolutionary and neuromuscular perspective.

Respiratory and muscular systems must integrate ventilation, oxygen delivery, and muscle activation to meet exercise demands. While decades of research have provided understanding of how these systems function individually, the principles regulating their dynamic coupling as a network remain unexplored. Our goal was to investigate how respiratory dynamics synchronize and integrate as a network with the activity of muscles during exercise, and assess how it responds to fatigue. Nine adults performed two graded cycling tests until exhaustion, starting at 0 W with 25 W·min-1 increments. Continuous synchronous recordings included electromyography (EMG) from right and left vastus lateralis and erector spinae, and respiration waveform via chest belt. Respiratory-muscular coupling was measured using the amplitude-amplitude cross-frequency coupling (ACFC) method. First, breathing rate was extracted from the respiration waveform. Second, EMG signals were decomposed into ten frequency bands [F1-F10], representing distinct neuromuscular processes. Last, cross-correlation coefficients (C) were computed as the ACFC outcome. We uncover novel network maps of respiratory-muscular dynamic interactions. We find that respiratory-muscular networks exhibit a complex hierarchical structure which depends on the role muscles play during exercise. Further, cross-correlations significantly increase with fatigue accumulation during exercise, indicating stronger integration between breathing and muscle activation under rising metabolic demand. This network-level adaptation shows that physiological responses to exercise arise not only from isolated systems, but also from their dynamic interactions as an integrated network. The network physiology approach utilized here contributes to the development of a new class of network-based markers to quantify multisystem interactions underlying human function during exercise.

Symptomatic lumbar spinal stenosis (sLSS) is associated with sagittal imbalance and degeneration of paraspinal muscles. While morphological changes are well documented, the functional relationships between electromyographic paraspinal fatigability, endurance, and global imbalance remain unclear. This study aimed to examine these relationships in preoperative patients with sLSS. In this cross-sectional study, 109 preoperative patients with sLSS underwent magnetic resonance imaging, EOS radiography, and a modified Biering-Sørensen test with bilateral surface electromyography (EMG) of the longissimus, iliocostalis and multifidus muscles. Paraspinal muscle fatigability was defined by three EMG-based indices: slope of median frequency (MDF) decline (Hz/s), normalized slope (%/s), and absolute MDF decrease (Hz). Endurance was defined as the duration of the modified Biering-Sørensen test. Global spinal imbalance was quantified using the Full Balance Integrated (FBI) score. Associations between fatigability, endurance, and FBI were assessed using Pearson correlation and stepwise multiple regression analyses. Valid EMG data were available for 90 of the 109 patients who performed the modified Biering-Sørensen test. Greater absolute MDF decreases (but not MDF slopes) were significantly associated with lower FBI scores (r = -0.38, p < 0.001). Longer endurance times correlated with both lower FBI scores (r = -0.41, p < 0.001) and greater absolute MDF decreases (r = 0.40, p < 0.001). Regression analysis revealed that absolute MDF decrease (β = -0.3, p = 0.004), endurance time (β = -0.1, p = 0.005), and age (β = 0.31, p < 0.001) independently predicted FBI, explaining 35% of its variance. Mediation analysis confirmed that the association between absolute MDF decrease and FBI was predominantly direct (71%) and only partially mediated through endurance time. In preoperative patients with sLSS, both reduced paraspinal endurance and lower absolute MDF decrease were independently associated with greater global spinal imbalance. The association between absolute MDF decrease and imbalance was only partially mediated through endurance time, indicating that these two measures capture complementary aspects of paraspinal muscle function. Since lower absolute MDF decrease coincided with shorter endurance times, reduced electromyographic fatigability in this population likely reflects diminished physiological reserve rather than enhanced neuromuscular efficiency.

High joint forces can contribute to the pathogenesis of patellofemoral pain in adolescents. Minimalist shoes may reduce patellofemoral joint forces during running compared with commonly worn motion-control shoes. Patellofemoral joint, lateral patella, and quadriceps forces will be lower, while gastrocnemius forces will be higher when adolescents run in minimalist shoes compared with motion control shoes. Cross-sectional study; Level of evidence, 2. This within-session 2-period randomized crossover study was conducted from March 2023 to September 2024. A total of 51 physically active adolescents aged between 12 and 19 years (mean age, 16.9 ± 2 years) (23 female adolescents [45%]) with patellofemoral pain were recruited from the general population. Kinematic, kinetic, and electromyography (EMG) data were collected during overground running in minimalist and motion-control shoes, with testing randomized within the same session. Patellofemoral joint force was measured during the stance phase of running using an EMG-informed neuromusculoskeletal model. The primary outcome was the resultant patellofemoral joint force (N). Secondary outcomes included lateral patellar force (defined as the peak force acting on the patella in the frontal plane) and quadriceps and gastrocnemius muscle forces (N). All outcomes were analyzed at peak using paired t tests. Compared with the motion control shoes, running in the minimalist shoes reduced peak resultant patellofemoral joint force by 7.5% (mean difference [MD], 363.2 N [95% CI, 666.8-59.5]; P = .02), reduced peak lateral patellar force by 7.8% (MD, 202.7 N [95% CI, 379-26.4]), and increased peak gastrocnemius muscle forces by 26.6% (MD, 449.3 N [95% CI, 298.6-560]). The minimalist shoe did not meaningfully alter quadriceps muscle forces compared with the motion-control shoe. As hypothesized, running in minimalist shoes reduced peak resultant patellofemoral joint and lateral patellar forces compared with running in motion-control shoes, while gastrocnemius forces were increased. Running in minimalist shoes did not meaningfully alter quadriceps muscle forces compared with motion-control shoes.

Waking-hours sedentary behaviour and its PA-independent associations with muscle strength, specific force, activation capacity, and fatigability in older adults.

A hybrid admittance control strategy for fluid-driven origami actuators in lower limb exoskeleton

This study evaluated the effects of passive back-support exoskeletons (BSEs) on biomechanical load and postural stability during simulated manual timber felling at three cutting heights. Twenty healthy adult male participants performed timber felling tasks under four BSE conditions (two rigid, one soft, and no BSE). During the tasks, electromyographic (EMG) activity, trunk angle, postural sway, and perceived exertion were measured. Results showed that rigid BSEs reduced trunk flexion and low back EMG activity at the middle cutting height, where trunk flexion was greatest. No significant changes were observed at low or high cutting heights, likely due to insufficient exoskeleton engagement. BSE use shifted postural control strategies rather than providing a uniform stabilizing effect. Additionally, BSEs lowered perceived exertion for the whole body and low back. These findings suggest that BSEs may help reduce low back loading at the middle cutting height during manual timber felling, but further field testing is warranted.

Enhancing fear of re-injury classification after ACL reconstruction by integrating biomechanical and electromyography data using multimodal machine learning methods.

This study aimed to test the causal role of sensorimotor experience in the development of facial mimicry. We systematically manipulated 4-month-old infants' experience with their own facial actions, and measured the effect on their sensorimotor cortex activation and facial mimicry when they observed others' facial actions. Infants in the mirror condition received two weeks of daily sensorimotor experience with their own facial actions via a toy mirror, while infants in the control condition played with the same toy without the mirror for the same amount of time. Before and after this experience, we measured infants' facial mimicry using electromyography (EMG) and their sensorimotor cortex activation using electroencephalography (EEG) while they observed videos of other infants' facial actions. As predicted, infants in the mirror condition showed a greater increase in sensorimotor cortex activation during the observation of other infants' facial actions than infants in the control condition. However, this greater neural activation did not translate into a greater increase in facial mimicry in the mirror group. These findings suggest that although the neural processing of others' facial actions was enhanced as a result of the sensorimotor training, longer training periods may be necessary for this to lead to greater facial mimicry. SUMMARY: We investigated the role of sensorimotor experience in infant facial mimicry by assigning infants to either a mirror or control condition Infants in the mirror condition received two weeks of daily mirror exposure Mirror training enhanced sensorimotor cortex activity during the observation of facial actions No corresponding increase in facial mimicry was observed.

Adolescent idiopathic scoliosis (AIS) features structural spinal deformity and impaired postural control, which may be associated with altered vestibular function and multisensory integration. Neuromodulatory approaches such as noisy galvanic vestibular stimulation (nGVS) and high-definition transcranial direct current stimulation (HD-tDCS) have shown promise in enhancing balance in healthy and older populations. However, whether peripheral and cortical vestibular neuromodulation exert distinct or combined effects on postural control in AIS remains unknown. This study aimed to compare the immediate post-stimulation effects of peripheral (nGVS), central (HD-tDCS), and combined (nGVS + HD-tDCS) vestibular modulation on postural control in AIS and explore their neuromuscular and cortical correlates. Forty adolescents with AIS were randomly assigned to sham, nGVS, HD-tDCS (anodal CP6), or nGVS+tDCS groups. Center of pressure (COP), surface electromyography (EMG) for bilateral gastrocnemius (GM), tibialis anterior (TA), and erector spinae (ES), and functional near-infrared spectroscopy (fNIRS) for bilateral inferior parietal lobule (IPL), superior parietal lobule (SPL), supplementary motor area (SMA), and primary motor cortex (M1) were simultaneously recorded during an eyes-closed foam-standing Romberg task to evaluate behavior, muscular and cortical responses before and after a single-session neuromodulation intervention. Active interventions (nGVS, HD-tDCS, and combined nGVS + HD-tDCS) significantly reduced COP path length and sway area versus sham, with the combined nGVS + HD-tDCS demonstrating the greatest reduction in path length. EMG analysis showed reduced gastrocnemius exertion following nGVS (right side) and combined stimulation (both sides). fNIRS revealed no hemodynamic changes after nGVS, while HD-tDCS increased activation in the right IPL, and enhanced functional connectivity (FC) between the right IPL and right SMA. Combined nGVS + HD-tDCS further amplified right IPL and right SPL activity, and strengthened connectivity within bilateral SMA and between the right IPL and right SMA. nGVS, HD-tDCS, and their combination improve postural control in AIS through distinct neuromodulation mechanisms. Combined stimulation was associated with the largest improvement in COP path length and broader cortical network modulation. Trial registration Registered at Chinese Clinical Trial Registry (ChiCTR2500110347) on July 25, 2025.

This study investigated the acute physiological responses to a novel combined resistance training (CB) protocol-integrating isometric pre-exhaustion with low-load, high-velocity, short-arc isotonic contractions-and compared them with low-intensity slow training (LST) and high-load (HL) training. Forty-eight healthy men were randomly assigned to one of three groups: LST (50% one-repetition maximum [1RM], slow tempo), HL (80% 1RM, normal tempo), or CB (40% 1RM; a 20-s isometric contraction followed by eight high-velocity, short-arc repetitions). Surface electromyography (EMG) and near-infrared spectroscopy (NIRS) of the vastus lateralis, alongside serum IGF-1 concentrations, were assessed during and following three leg-press sets. Despite utilizing a 40% 1RM load, the CB protocol elicited mean EMG amplitudes significantly greater than LST during the final set (p = 0.009, g = 1.23). NIRS analysis demonstrated a significantly lower change in tissue oxygen saturation (ΔStO2) in the CB group compared to HL from the initial set (p = 0.001; g = 1.19), highlighting rapid intramuscular hypoxia. Furthermore, third-set integrated EMG was significantly higher in CB than in both HL (p = 0.002, g = 1.13) and LST (p < 0.001, g = 1.63). Serum IGF-1 concentrations exhibited a significant post-exercise elevation across all groups (main effect of time: p < 0.001, ηp2 = 0.712). By concurrently demanding high neural drive and inducing profound metabolic stress, the time-efficient CB protocol provides a robust physiological stimulus despite minimal mechanical loading. This approach serves as a practical, joint-friendly alternative for populations necessitating reduced mechanical stress. UMIN-CTR (UMIN000060486).

To compare the immediate effects of two neurodynamic mobilization techniques (flossing vs. tensioning) on the sciatic nerve and hamstring muscle tissues, using different stretching intensities. Twenty physically active volunteers performed a randomized, study comprising seven conditions (six stretching + control). Interventions included static stretching (SS), neurodynamic tensioning (TENS), and neurodynamic flossing (FLOS), applied at 100% (pain threshold) or 90% maximal range of motion, using 5 × 60-s sets. Shear wave elastography (SWE) was used to assess sciatic nerve and biceps femoris stiffness before and immediately after the interventions. Measurements included flexibility tests (passive knee extension (PKE), stand and reach (SR), slump), and hamstring strength (MVIC) alongside with electromyography (EMG). SWE of the sciatic nerve showed a significant condition × time interaction (p < 0.001), with a significant decrease only after flossing at maximal intensity (FLOS100); The biceps femoris (BF) shear wave velocity (SWV) decreased over time (p = 0.004) independently of the condition. Flexibility outcomes significantly improved after all stretching interventions (p < 0.001). Nevertheless, FLOS100 produced significantly greater improvements in sciatic nerve mobility than SS at maximal intensity (p = 0.017). MVIC significantly decreased from PRE to POST (p = 0.009) across all conditions, with no condition × time interaction (p = 0.991). The EMG activity remained unchanged for BF muscle while semitendinosus (ST) EMG showed a significant decrease over time (p = 0.017). Neurodynamic flossing at maximal intensity reduced sciatic nerve stiffness and mobility in asymptomatic individuals. These neural adaptations suggest flossing should be prioritized for neural tissue, while all stretching techniques similarly affect muscle stiffness.

Damage to the corticospinal tract after stroke and spinal cord injury (SCI) often results in persistent upper extremity (UE) impairment. Transcutaneous spinal stimulation (TSS) and robotic technologies have been explored as approaches to facilitate motor training; however, their combined effects on UE sensorimotor recovery remain poorly understood. The purpose of this study was to examine the effects of TSS combined with UE robotic training in individuals with chronic stroke or SCI. Five participants with stroke and six with SCI completed a 14-week, sham controlled, single blind crossover study consisting of four total weeks of assessments (one week each pre and post for both training phases), four weeks of UE training with sham TSS, a two-week washout period, and four weeks of UE training with active TSS. Each one-hour session (three days/week) included robotic exoskeleton-assisted UE movements and hand grip training, performed concurrently with sham or active TSS. Assessments included electrophysiological measurements and standardized rehabilitation outcomes. Descriptive analysis revealed meaningful individual improvements masked by group-level heterogeneity. In the stroke group, three participants showed grip strength improvement (assessed without stimulation) after the active phase (+ 9.4 Newtons [N] to + 23.9N), with two-to-four-fold increases in forearm muscle activation. Mean Fugl-Meyer overall UE scores improved from 89 to 94.2. In the SCI group, two participants showed grip strength gains. One participant exhibited a six-fold immediate force increase (1.0N to 6.2N) during stimulation. Another participant achieved improved grip strength without stimulation (23.9N to 36.8N) and a three-fold increase in electromyography (EMG) activity from the flexor carpi radialis and first dorsal interosseous muscles, alongside partial pin-prick sensory recovery and self-reported restoration of previously affected perspiration during the active TSS phase. Varied outcomes in participants confirm that therapeutic effects of combined TSS and robotic UE training are highly individualized. Three critical elements must be blended for the best outcomes of this combinatorial approach: residual UE function, a curated stimulation paradigm, and tailored UE training that provides appropriate challenge, intensity, and salience. The results suggest TSS with UE robotic training hold key potential when considered in the context of the physiological and functional profile of each participant.

People with movement disabilities face difficulties in independent mobility. The main objective of this study was to develop and evaluate a real-time electro-myography (EMG) based wheelchair control framework with upper arm or neck muscles and to investigate feasibility for assistive mobility applications. A feature optimisation framework was employed to extract the most significant features for movement recognition. The proposed model was trained and tested in both offline and real-time control. Feasibility was assessed through classification accuracy, repeatability measures, response latency and preliminary validation involving two individuals with disabilities. With subject-independent methodology, wheelchair activation with upper arm muscles achieved an accuracy of 95% in real time, whereas for neck muscles, it was 98.6% in able-bodied participants. For neck muscles, two participants with disabilities, namely a transhumeral amputee and a mobility-impaired participant because of poliomyelitis were evaluated and achieved an accuracy of 100%. The average system response latency for upper arm movements was found to be 430 ms for able-bodied participants, whereas for neck muscles, it was 360 ms for able-bodied participants and 400 ms for participants with disabilities. The proposed framework demonstrated the feasibility of real-time EMG-based wheelchair control in a controlled environment. However, further studies involving larger and more diverse participant cohorts are needed to evaluate its generalisability and broader clinical applicability.

Although effort alters the neural commands driving ballistic contractions, its impact on endpoint accuracy remains poorly understood. Here, we examined how effort-related changes in trajectory fluctuations and inconsistency (trajectory dynamics) and muscle activation affect the accuracy of ballistic goal-directed contractions. Eighteen healthy young adults (26.4 ± 6.4years; 9 women) performed ballistic isometric index finger abductions for 40 trials at each of the seven randomly assigned force levels (2, 5, 15, 30, 50, 70, 85% of maximum voluntary contraction; MVC). We quantified endpoint accuracy (bias error, absolute error), force trajectory dynamics, and first dorsal interosseous (FDI) muscle activity across different frequency bands. Bias error showed effort-dependent reversal of accuracy, with overshooting at low force levels, maximum accuracy at 30% MVC, and undershooting at high effort levels. Absolute force error decreased with effort, reflecting a 2/3rd power-law trend, indicating an improvement in accuracy with increasing force level regardless of the direction. Trajectory fluctuations and muscle activity changed with effort level, whereas an increase in 8-13Hz electromyography (EMG) power predicted reductions in bias error from 2-30% MVC. These findings demonstrate an effort-dependent effect on endpoint accuracy and identify trajectory dynamics and muscle activation characteristics that explain endpoint accuracy changes in targeted ballistic contractions.

Severe maxillary atrophy complicates implant rehabilitation due to limited bone support and sinus pneumatization. The All-on-4 protocol provides predictable results, while zygomatic implants may offer a graftless alternative. This study compared conventional All-on-4 with a modified protocol using 2 zygomatic and 2 conventional implants. Twenty-four patients with edentulous atrophic maxillae were assigned to 2 groups according to anatomical suitability and treatment planning. The control group (n=12) received 4 conventional implants, and the study group (n=12) received 2 zygomatic plus 2 anterior implants. Outcomes included electromyographic (EMG) assessment of masseter and temporalis activity, as well as implant stability. Both treatment modalities exhibited positive clinical and functional results throughout the follow-up duration. Implant stability values grew progressively in both groups, with no statistically significant difference observed between them. Electromyographic assessment indicated enhancement in muscle activity post-rehabilitation in both treatment cohorts, with no statistically significant differences in the majority of examined parameters. Within the limitations of this study, rehabilitation of the atrophied maxilla using 2 zygomatic implants combined with 2 conventional implants demonstrated acceptable clinical and functional outcomes during the evaluated follow-up period. ClinicalTrials.gov Identifier: NCT05108324.

BackgroundDistal myopathies (DMs) comprise a heterogeneous group of hereditary muscle diseases characterized by predominant distal muscle weakness and atrophy overlapping with hereditary neuropathies, leading to diagnostic delays or misclassification.ResultsWe conducted a retrospective analysis of 125 patients from 103 families with DMs revealed at a federal genetics referral center in Russia from 2010 to 2025, representing the largest Russian DM cohort. Causative variants were identified in 20 genes, most commonly in the GNE (30.1%), DYSF (13.6%), and TTN (9.7%) genes. Although distal muscle involvement predominated, lower limb muscle magnetic resonance imaging (MRI) showed proximal involvement in 93.4% (71/76) of cases regardless of disease stage. Across the cohort, gracilis, rectus femoris, and tibialis posterior were relatively spared. Referral misdiagnosis as hereditary neuropathy occurred in 32.8% (41/125) of cases. To characterize diagnostic pitfalls, we compared patients initially referred with neuropathy to those referred with DM. We demonstrated that group differences were evident solely in the needle electromyography (EMG) reports, while clinical features and lower limb muscle MRI data were broadly comparable. We analyzed the probable causes of EMG misinterpretations, which most commonly included severe spontaneous activity being mistaken for active denervation, high-amplitude motor unit potentials being misclassified as neurogenic, and, in some cases, the wrong choice of muscle for the study.ConclusionAccording to our data, one-third of patients with DM were initially referred for suspected neuropathy. In many cases, misclassification was likely due to pitfalls in EMG interpretation, highlighting the need for careful EMG analysis in patients with myopathies.