Electromyography Research Articles

Dorsal Column Spinal Cord Stimulation Attenuates Brain-Spine Connectivity through Locomotion and Visuospatial-Specific Area Activation in Progressive Freezing of Gait

Introduction: Freezing of gait (FOG) is a clinical phenomenon with major life impairments and significant reduction in quality of life for affected patients. FOG is a feature of Parkinson’s Disease and a hallmark of primary progressive freezing of gait (PPGF), currently reclassified as Progressive Supranuclear Palsy-progressive gait freezing (PSP-PGF). The pathophysiology of FOG and particularly PGF, which is a rare degenerative disorder with a progressive natural history of gait decline, are poorly understood. Mechanistically, changes in oscillatory activity and synchronization in frontal cortical regions, the basal ganglia, and the midbrain locomotor region have been reported, indicating that dysrhythmic oscillations and coherence could play a causal role in the pathophysiology of FOG. DBS and SCS have been tested as therapeutic neuromodulation avenues for FOG with mixed outcomes. Methods: We analyzed gait and balance in three patients with PSP-PGF who received percutaneous thoracic spinal cord stimulation (SCS) and utilized magnetoencephalography (MEG), electroencephalography (EEG), and electromyography (EMG) to evaluate functional connectivity between the brain and spine. Results: Gait and balance did not worsen over a 13-month period. This observation was accompanied by decreased beta-band spectral power in the whole brain and particularly in the basal ganglia. This was accompanied by increased functional connectivity in and between the sensorimotor cortices, basal ganglia, temporal cortex, and cerebellum, and a surge in corticomuscular coherence when SCS was paired with visual cues Conclusion: Our results suggest synergistic activity between brain and spinal circuits upon SCS for FOG in PGF, which may have implications for future brain-spine interfaces and closed-loop neuromodulation for patients with FOG.

Hypercapnia impacts neural drive and timing of diaphragm neuromotor control.

The neuromotor control of the diaphragm muscle (DIAm) involves motor unit recruitment, sustained activity (incrementing and decrementing), and motor unit derecruitment, phases that may be modified to maintain ventilation across conditions. The primary goal of the present study was to investigate the effects of hypercapnia, which increases respiratory rate and tidal volume, on DIAm neuromotor control in awake rats. We recorded DIAm electromyography (EMG) using implanted chronic fine-wire electrodes in nine Sprague-Dawley rats during normocapnia and hypercapnia (7% CO2). The durations of motor unit recruitment/derecruitment were estimated by evaluating stationarity of DIAm EMG activity during normocapnia and hypercapnia; the motor unit recruitment/derecruitment durations were used to evaluate RMS EMG recruitment/derecruitment amplitudes. Overall, hypercapnia reduced the burst duration by ~40% and increased respiratory rate by ~50%. The change in the burst duration was primarily attributable to a 57% decrease in the peak-to-offset duration of the DIAm RMS EMG signal, suggesting a suppression of postinspiratory activity. Although neither the recruitment duration nor the onset-to-peak duration changed with hypercapnia, both the recruitment and peak amplitudes increased by 11% and 23% respectively. Therefore, although hypercapnia increases the number of motor units being recruited and their discharge rates, ventilation is primarily increased by increasing respiratory rate. Additionally, hypercapnia eliminated the decrementing sustained activity phase and consequently increased derecruitment amplitude by 171%. The results of the present study reveal that respiratory rate is increased chiefly by reducing the decrementing (i.e. "postinspiratory") phase of DIAm EMG activity.

Relationship Between Mandibular Position, Activation of the Masticatory Musculature and Free-Throw Accuracy in Female Basketball Players.

Current research relates jaw clenching to athletic performance, in terms of force and agility. However, the impact of jaw clenching on sports accuracy is unclear. To analyse the impact of jaw position and chewing type on free-throw accuracy and electromyographic (EMG) activity of masticatory muscles during free-throws. Cross-sectional study with 25 female basketball players aged 18-44. Each participant executed 18 free-throws under three different jaw conditions: mandibular rest, maximum intercuspation, and with interdental cotton rolls, in randomised order. Chewing type and jaw position were not associated with shooting accuracy (p = 0.106; p = 0.778). There was a positive correlation between EMG activity of the right masseter and free-throw accuracy at maximum intercuspation (rs = 0.402; p = 0.046). In contrast, negative correlations were found with other muscles when the occlusal vertical dimension was altered (rs = -0.619, p = 0.001; rs = -0.490; p = 0.013; rs = -0.534; p = 0.006). The chewing type affected the EMG of the left masseter in the altered occlusal vertical dimension (H = 6.969; p = 0.031). Significant differences in EMG recordings were observed across different mandibular positions during free-throws (p < 0.001). While jaw positioning and chewing type do not impact free-throw accuracy in amateur female basketball players, the EMG activity of masticatory muscles is linked to shooting performance. This highlights the need for further research on motor behaviour of masticatory muscles in precision sports, especially for athletes using intraoral devices.

Hybrid Functional Near-Infrared Spectroscopy System and Electromyography for Prosthetic Knee Control

The increasing number of individuals with limb loss worldwide highlights the need for advancements in prosthetic knee technology. To improve control and quality of life, integrating brain–computer communication with motor imagery offers a promising solution. This study introduces a hybrid system that combines electromyography (EMG) and functional near-infrared spectroscopy (fNIRS) to address these limitations and enhance the control of knee movements for individuals with above-knee amputations. The study involved an experiment with nine healthy male participants, consisting of two sessions: real execution and imagined execution using motor imagery. The OpenBCI Cyton board collected EMG signals corresponding to the desired movements, while fNIRS monitored brain activity in the prefrontal and motor cortices. The analysis of the simultaneous measurement of the muscular and hemodynamic responses demonstrated that combining these data sources significantly improved the classification accuracy compared to using each dataset alone. The results showed that integrating both the EMG and fNIRS data consistently achieved a higher classification accuracy. More specifically, the Support Vector Machine performed the best during the motor imagery tasks, with an average accuracy of 49.61%, while the Linear Discriminant Analysis excelled in the real execution tasks, achieving an average accuracy of 89.67%. This research validates the feasibility of using a hybrid approach with EMG and fNIRS to enable prosthetic knee control through motor imagery, representing a significant advancement potential in prosthetic technology.

Psychological interventions for the self-regulated enhancement of music performance: A systematic review

Psychological interventions to enhance musicians’ self-regulation are increasingly being recognized as essential for supporting them in their development and optimization of performance skills. The aim of this review was to provide a synthesis of such interventions and examine their effects on expert-rated music performance quality. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol, we initially identified 3,182 articles, of which we selected 89 studies. Using the theoretical framework of self-regulated learning, we present a comprehensive overview of experimental, quasi-experimental, and single-case studies published until April 2022 that tested how musicians can improve their performance through self-regulation strategies such as goal setting, imagery, attention focusing, relaxation, and self-evaluation. The results show mixed evidence with mostly positive or non-significant effects, indicating that expressive writing, external focus, feedback, combined electromyographic (EMG) and electroencephalographic (EEG) biofeedback, and imagery combined with physical practice can increase expert-rated music performance quality. The reported methodological quality, the applied performance task and evaluation, and potential mechanisms underlying the interventions should be considered when interpreting the results. We critically discuss possible improvements for future studies, as well as practical implications.

Exploring the Relationship between Masseter and Cervical Vestibular-Evoked Myogenic Potentials in Young Adults with Hearing Thresholds Less Than or Equal to 15 dB HL.

Cervical vestibular-evoked myogenic potentials (cVEMPs) and masseter vestibular-evoked myogenic potentials (mVEMPs) are considered to have a common saccular origin. While a few studies have examined both vestibular-evoked myogenic potentials (VEMPs) in individuals with brainstem disorders as part of a test battery, the relation between these two potentials has rarely been the subject of discussion. The present study explored the relation between mVEMPs and cVEMPs using electromyography (EMG)-scaled parameters in normal-hearing young adults. Within-subject study design. Twenty young adults between 18 and 39 years of age (11 males, 9 females) participated in the study. cVEMP and mVEMP were performed on all the participants at 95 dBnHL with 500 Hz tone burst stimuli. Various VEMP parameters were evaluated including P13 and N23 peak latencies, the amplitude of the P13-N23 complex, and the Interaural Amplitude Asymmetry Ratio in EMG-scaled and unscaled conditions. All participants exhibited a 100% response rate for cVEMP and mVEMP responses. There were no significant ears and gender effect for both cVEMP and mVEMP. No correlation was found between cVEMP and mVEMP. There was no significant difference found between P1 and N1 latency values of cVEMP and mVEMP; however, a significant variation was observed for peak-to-peak amplitude both in EMG-scaled and unscaled conditions between cVEMP and mVEMP. Minimal to no association between any parameters of cVEMPs and mVEMPs suggests no significant relationship between these two VEMPs.

Optogenetic activation of serotonergic neurons changes masticatory movement in freely moving mice.

The serotonergic system modulates the neural circuits involved in jaw movement; however, the role of serotonin (5-HT) neurons in masticatory movement remains unclear. Here, we investigated the effect of selective activation of 5-HT neurons in the dorsal raphe nucleus (DRN), or the raphe obscurus nucleus (ROb), on voluntary masticatory movement using transgenic mice expressing the channelrhodopsin-2 (ChR2) mutant (C128S) in central 5-HT neurons. During voluntary mastication, DRN blue light illumination increased masticatory frequency and decreased the root mean square peak amplitude of electromyography (EMG) in the masseter muscles. DRN blue light illumination also decreased EMG burst duration in the masseter and digastric muscles. These changes were blocked by a 5-HT2A receptor antagonist. Conversely, ROb blue light illumination during voluntary mastication did not affect masticatory frequency and EMG bursts in the masseter and digastric muscles. DRN or ROb blue light illumination during the resting state did not induce rhythmic jaw movement such as mastication but induced an increase in EMG activity in masseter and digastric muscles. These results suggest that both DRN and ROb 5-HT neurons may facilitate jaw movement. Furthermore, DRN 5-HT neuron may contribute to changes in masticatory patterns during the masticatory sequence.

Interleukin-12 modulates sleep–wake activity and improves performance in a memory task

Abstract Background Cytokines, known for their pro- and anti-inflammatory roles, are also key regulators of sleep–wake cycles. Classical pro-inflammatory cytokines, such as interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-α), are associated with increased sleep, particularly slow-wave sleep (SWS), while anti-inflammatory cytokines, like interleukin-10 (IL-10), generally reduce sleep duration. Given the essential role of sleep in memory consolidation, this study aimed to investigate whether interleukin-12 (IL-12), a pro-inflammatory cytokine, could increase sleep duration following a memory acquisition task and subsequently improve memory performance. Male Swiss mice were surgically implanted with electrodes for electrocorticogram (ECoG) and electromyogram (EMG) recordings to track their sleep–wake cycles. After a recovery period, baseline sleep–wake activity was recorded. The mice were then randomly assigned to two groups and treated with either IL-12 (0.5 µg, i.p.) or a phosphate-buffered saline (PBS, i.p.) control, administered immediately before the multiple-trial inhibitory avoidance (MTIA) task, a behavioral test used to assess memory performance. Following the memory acquisition session, sleep–wake activity was immediately recorded for a continuous 24-h period. Results Mice treated with IL-12 exhibited longer latency to cross into the dark compartment during the MTIA test, indicating improved memory retention compared to the control group. Interestingly, this improved performance was associated with prolonged wakefulness, particularly in the first three hours after task acquisition. Conclusion The study shows that IL-12 can improve memory retention through prolonged wake episodes rather than increased sleep. This finding challenges the conventional understanding that sleep is the primary state for memory consolidation, suggesting that under specific conditions, wakefulness may also play a key role in supporting memory processes. Further research is needed to explore the underlying mechanisms of IL-12's cognitive effects.

Comparisons of different electrical stimulation modalities for treating visceral pain in a rodent model of irritable bowel syndrome

The purpose of this study was to investigate the effects of different electrical stimulation methods (bilateral electroacupuncture (BEA), unilateral EA (UEA), transcutaneous electrical acustimulation (TEA, stimulation via surface electrodes placed at acupoints), and sacral nerve stimulation (SNS)) on visceral pain in a rodent model of irritable bowel syndrome (IBS). Ten-day-old male and female pups were treated with 0.2 ml of 0.5% acetic acid (AA) solution. Visceral sensitivity was assessed using an electromyogram (EMG) in response to graded colorectal distension. In the first experiment, bilateral EA at ST36 acupoint was performed with different parameters in male rats to determine the best stimulation parameters. In the second experiment, male rats were randomly assigned into the Sham, BEA, UEA, TEA, and SNS groups to determine the best stimulation method. Lastly, the AA-treated female rats were randomly assigned into the BEA and sham groups to investigate a potential treatment difference between the sexes. Two distinct sets of stimulation parameters were used: Set 1 (100 Hz, 0.5 ms pulse width, 0.1 s ON, 0.4 s OFF, 0.4–3.0 mA current) and Set 2 (25 Hz, 0.5 ms pulse width, 2 s ON, 3 s OFF, 0.4–3.0 mA current).Results (1) The parameter set of 100Hz was found to be most effective in reducing visceral pain. (2) Both acute UEA and TEA effectively relieved visceral pain, whereas acute SNS did not exhibit such an effect. (3) Acute BEA improved visceral pain in both male and female rats.Conclusions These findings suggest that transcutaneous ST36 stimulation is as effective as direct ST36 stimulation and unilateral ST36 stimulation is comparable to bilateral stimulation. Development of a novel therapy using unilateral transcutaneous ST36 stimulation is warranted.

Variable Resistance Training Combined With Static Traction Computer Vision Applied in Neck and Shoulder Rehabilitation Training for College Students

This study evaluates the effectiveness of static traction combined with variable resistance training in rehabilitating college students with neck and shoulder diseases. Ninety students were randomly assigned to receive either static traction alone or combined therapy. Visual analogue scale (VAS), neck disability index (NDI), cervical range of motion, electromyography (EMG), and soft tissue parameters were assessed pre- and post-treatment. Both groups showed improved VAS and NDI scores post-treatment, with greater enhancements in the combined therapy group. Cervical range of motion, EMG values, and soft tissue parameters also favored the combined therapy. Statistical analysis revealed significant differences (P&amp;lt;0.05) between groups. Static traction combined with variable resistance training effectively improves neck and shoulder function, reduces pain, and enhances rehabilitation outcomes compared to static traction alone. This approach shows promise for optimizing rehabilitation in college students with similar musculoskeletal conditions.

Fasciculation potentials are related to the prognosis of amyotrophic lateral sclerosis.

Some prognostic biomarkers of amyotrophic lateral sclerosis (ALS) have been described; however, they are inadequate for satisfactorily predicting individual patient outcomes. Fasciculation potentials (FPs) on electromyography (EMG) are useful for the early diagnosis of ALS, and complex FPs are associated with shorter survival in ALS. In this study, we investigated the relationship between the proportion of muscles with FPs, biochemical markers, and the prognosis of ALS. 89 Patients with ALS were retrospectively classified into three groups based on the interval from onset to death or tracheostomy (less than 1 year: fast progression; from 1 year to less than 3 years: average progression; 3 years or more: slow progression). We performed statistical analysis of the electrophysiological findings, including the percentage of examined muscles with FPs, and biochemical markers evaluated on admission. Patients with fast ALS progression had a higher percentage of muscles with FPs (93.1% vs. 37.9%, P<0.001) and lower uric acid (UA) levels (male: 4.19 mg/dl vs 5.55 mg/dl, P<0.001; female: 3.71 mg/dl vs 5.41 mg/dl, P<0.001) than patients with slow progression. Survival curves demonstrated a relationship between these factors and the survival time in patients with ALS. Furthermore, UA levels were correlated with the percentage of muscles with FPs. Our electrophysiological findings suggest that ALS presents with multisystem neurological manifestations, and these manifestations differed among the groups classified by disease progression. The percentage of muscles with FPs on EMG and serum UA levels were especially associated with the prognosis of ALS.

ACTIVE, ACTUATED, AND ASSISTIVE: A SCOPING REVIEW OF EXOSKELETONS FOR THE HANDS AND WRISTS

BACKGROUND: Assistive technology is often incorporated into rehabilitation and support for those impacted by upper limb impairments. When powered, these devices provide additional force to the joints of users with muscle weakness. Actuated devices allow dynamic movement compared to splints, therefore improving the ability to complete activities of daily living. However, these devices are not often prescribed and are underrepresented in research and clinical settings. OBJECTIVE: This review examines the current body of literature concerning devices designed to aid the hands and wrists in daily activities. Focusing on active, powered, and actuated devices, to gain a clearer understanding of the current limitations in their design and prescription. METHODOLOGY: The scoping review was conducted using the PRISMA-ScR guidelines. A systematic search was done on MEDLINE, EMBASE, Scopus, Web of Science, and NHS the Knowledge Network from inception to May 2023. Articles were included if the device was portable; supported the hands and wrist actively using an actuator; and could be used for assistive living during or post-rehabilitation period. FINDINGS: A total of 135 studies were included in the analysis of which 34 were clinical trials. The design and control methods of 121 devices were analyzed. Electrical stimulation and direct mechanical transmission were popular actuation methods. Electromyography (EMG) and joint movement detection were highly used control methods to translate user intentions to device actuation. A total of 226 validation methods were reported, of which 44% were clinically validated. Studies were often not conducted in operational environments with 69% at technology readiness levels ≤ 6, indicating that further development and testing is required. CONCLUSION: The existing literature on hand and wrist exoskeletons presents large variations in validation methods and technical requirements for user-specific characteristics. This suggests a need for well-defined testing protocols and refined reporting of device designs. This would improve the significance of clinical outcomes and new assistive technology. Layman's Abstract Assistive devices are often incorporated into rehabilitation and support for those impacted by upper limb impairments. When powered, these devices provide additional force for users with muscle weakness. Unlike splints, these devices do not constrict movement, therefore improving the ability to complete activities of daily living. However, these devices are rarely prescribed or presented in research and clinical settings. This review examines the current literature concerning powered devices that aid the hands and wrists to investigate who uses them, how they are designed and how they are validated. The scoping review was conducted using a validated guideline. A systematic search was done on 5 databases up to May 2023. Articles were included if the device was portable; supported the hands and wrist using motors; and could be used for everyday tasks. A total of 135 studies were included in the analysis, of which 34 were clinical trials. The design and method of device function of 121 devices were analysed. Muscle and joint movement detection were highly used to control device movement. A total of 226 validation methods were reported, of which 44% were clinically validated. Studies were often conducted in research and clinical environments (69%) rather than at home settings. In conclusion, existing literature on hand and wrist exoskeletons presents large variations in design, control methods and validation practices. This suggests a need for well-defined testing protocols. This would improve the significance of clinical outcomes of new assistive technology. Article PDF Link: https://jps.library.utoronto.ca/index.php/cpoj/article/view/43827/33279 How To Cite: Galbert A, Buis A. Active, actuated, and assistive: A scoping review of exoskeletons for the hands and wrists. Canadian Prosthetics &amp; Orthotics Journal. 2024; Volume 7, Issue 1, No.9. https://doi.org/10.33137/cpoj.v7i1.43827 Corresponding Author: Professor Arjan Buis, PhDDepartment of Biomedical Engineering, Faculty of Engineering, University of Strathclyde, Glasgow, Scotland.E-Mail: arjan.buis@strath.ac.ukORCID ID: https://orcid.org/0000-0003-3947-293X

BIOMECHANICAL ASSESSMENT OF SCAPULAR PLANE ELEVATION EXERCISE WITH DIFFERENT MODES OF RESISTANCE IN SUBJECTS WITH AND WITHOUT IMPINGEMENT SYNDROME.

Background: Strengthening the rotator cuff and scapular stabilizers is usually prescribed for subjects with shoulder pain and is done either using dumbbells or TheraBand. The resistance offered by elastic Theraband increases with increase in change from initial length and therefore the resistance offered by TheraBand, and dumbbell differs across the range of motion. Objectives: The purpose of the study is to evaluate the scapular kinematics and activity of prime mover (Anterior Deltoid) while using two different modes of resistance (TheraBand v/s dumbbell) in subjects with and without impingement syndrome. Methods: Twenty-two asymptomatic subjects and 12 subjects with impingement syndrome were included. 3D motion sensors were attached over the humerus, scapulae and trunk to capture movements of the shoulders as the subject performed scapular elevation without load, with yellow Theraband or 2 Kg Dumbbell. Simultaneous electromyography (EMG) activity of anterior Deltoid was measured and analyzed as percentage of maximum voluntary contraction. Results: During arm elevation, scapular Upward rotation was significantly greater at 90° with TheraBand® as compared to unloaded. It was also greater at 120° as compared to unloaded and dumbbell conditions (p&lt;0.001) during elevation and lowering phase. Scapula upward rotation was significantly lesser at 30° with TheraBand® as compared to other conditions. Conclusion: This study found significant downward rotation and anterior tilt of scapula with TheraBand during lowering phase of exercise as compared to dumbbell and unloaded. The alterations of kinematics may help therapists make informed decisions while making exercise prescriptions.

Characteristics, Relationships, and Differences in Muscle Activity and Impact Load Attenuation During Tennis Forehand Stroke with Different Grips

In forehand strokes with different grips in tennis, the forearm muscle activities, the distribution and attenuation of the impact loads, and the effects of the muscles on the impact load attenuation exhibited different characteristics. This study aimed to explore these characteristics by analyzing electromyography (EMG) and acceleration data, and comparing the differences between the Eastern and Western grips. Fourteen level II or above tennis players (ten males, aged 22.4 ± 3.6 years; four females, aged 19.8 ± 2.0 years) were recruited and instructed to perform forehand strokes using the Eastern and Western grips, respectively. The EMG of eight forearm muscles and the acceleration data at the ulnar and radial sides of the wrist and elbow were collected. The root mean square (RMS), the peaks of the impact load, the amplitude of impact load attenuation (AC), and the jerk value (Jerk) were calculated. The cross-correlation coefficients and time delays of EMG–EMG, EMG–AC, and EMG–jerk were obtained using the cross-correlation method. The results showed that in the Eastern grip group (group E), the RMS of the flexor carpi ulnaris (FCU) was significantly greater than that in the Western grip group (group W). In group E, the peaks of impact load, AC, and Jerk on the Y axis of the wrist ulnar side were all significantly higher than those in group W. The activity of the extensor digitorum commonis (EDC) had significantly different effects on the amplitude and rate of impact load attenuation at specific locations in different grips, especially at the elbow (p &lt; 0.05). The conclusion indicated that the FCU exhibited higher levels of EMG activity in the Eastern grip. This grip responded to greater impact loads with more substantial and rapid attenuation on the wrist ulnar side. Furthermore, the EDC appeared to contribute more to the amplitude of impact load attenuation in the Western grip and to have a more significant influence on the rate of impact load attenuation in the Eastern grip, especially at the elbow. These results suggest that tennis players and coaches should pay more attention to improving the strength of the EDC and FCU, which can improve sports performance and comfort, as well as prevent sports injuries.

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.

Biomechanical perspectives on college students’ psychological well-being and their impact on academic performance

Academic performance among college students is prejudiced by a complex interplay of psychological well-being, physical activity, and biomechanical health. While previous research has often focused on individual factors such as mental health or physical activity, there is a growing need for an integrative approach to understand how these elements interact and collectively impact academic performance. This study aims to explore these relationships among 126 students from four universities in China, using a comprehensive methodology that includes psychological assessments (GHQ-28, PSS, MHI), wearable activity trackers for physical activity and sleep monitoring, and biomechanical evaluations through motion capture and electromyography (EMG). The study adopts a multi-faceted analytical approach, including hierarchical regression, path analysis, and latent variable modelling. Hierarchical regression revealed that psychological factors alone explained 21.1% of the variance in GPA (R2 = 0.211), while adding biomechanical and physical activity factors increased the explanatory power to 35.0% (R2 = 0.350). Path analysis indicated that psychological well-being had a direct negative effect on academic performance (β = −0.41, p &lt; 0.001) and an indirect effect mediated through physical activity (indirect β = −0.089, p = 0.0021). Latent variable modelling demonstrated that psychological well-being, physical activity, and biomechanical health constructs collectively explained 52% of the variance in academic performance.

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.

Musculoskeletal mimics for lumbosacral radiculopathy. Part 1: Theoretical considerations.

The diagnosis of lumbosacral radiculopathy includes the exclusion of common musculoskeletal conditions that can cause similar symptoms. Neurology and physiatry physicians use history taking and physical examination findings to develop a differential diagnosis. Appropriate diagnostic testing is then utilized to narrow down this differential diagnosis to determine a working hypothesis of the cause of a patient's symptoms, leading to a treatment plan. There are stark limitations of patient symptoms and physical examination findings in making the diagnosis of lumbosacral radiculopathy and added value of a combination of symptoms and signs to distinguish patients with lumbosacral radiculopathy from patients with mimic disorders. Diagnostic tests have variable strengths and limitations in helping to confirm this diagnosis, contrasting the high sensitivity and lower specificity of magnetic resonance imaging (MRI) with the high specificity but lower sensitivity of electromyography (EMG). Further complexity is added to the task of making a diagnosis and setting a treatment plan by the fact that these disorders are common and interact with each other; they are present concomitantly in up to 25% of patients presenting for electrodiagnostic evaluation. A companion paper will review common musculoskeletal mimics of lumbosacral radiculopathy and provide tools to anchor testing for those conditions to the traditional neurological evaluation of lumbosacral radiculopathy.

Hip Flexor Muscle Activation During Common Rehabilitation and Strength Exercises.

Background/Objectives: The iliopsoas muscle plays an essential role in lumbopelvic and hip anterior stability, which is particularly important in the presence of limited osseous acetabular coverage anteriorly as in hip dysplasia and/or hip micro-instability. The purpose of this systematic review is to (1) describe iliopsoas activation levels during common rehabilitation exercises and (2) provide an evidence-based exercise progression for strengthening the iliopsoas based on electromyography (EMG) studies. Methods: In total, 109 healthy adult participants ranging from ages 20 to 40 were included in nine studies. PubMed, CINAHL, and Embase databases were systematically searched for EMG studies of the psoas, iliacus, or combined iliopsoas during specific exercise. The Modified Downs and Black Checklist was used to perform a risk of bias assessment. PROSPERO guidelines were followed. Results: Nine studies were included. Findings suggest that the iliopsoas is increasingly activated in ranges of hip flexion of 30-60°, particularly with leg lowering/raising exercises. Briefly, >60% MVIC activity of the iliopsoas was reported in the active straight leg raise (ASLR) in ranges around 60° of hip flexion, as well as with supine hip flexion and leg lifts. In total, 40-60% MVIC was found in exercises including the mid-range of the ASLR around 45° of hip flexion and lifting a straight trunk while in a hip flexed position. Conclusions: The findings suggest that exercises in increased hip flexion provide greater activation of the iliopsoas compared to exercises where the trunk is moving on the lower extremity. Iliopsoas activation can be incrementally progressed from closed to open kinetic chain exercises, and eventually to the addition of external loads. The proposed exercise program interprets the results and offers immediate translation into clinical practice.

Effects of Extrinsic and Intrinsic Motivation on Selective Activation of Shoulder Girdle Muscles During the Barbell Bench Press Exercise

Background/Objectives: This study aimed to investigate the effects of intrinsic and extrinsic motivation on selective muscle activation of the shoulder girdle during the barbell bench press. Specifically, this research focused on how attentional focus on individual muscles, such as the anterior deltoid (AD), pectoralis major (PM), and triceps brachii long (TBL), could influence their electromyographic (EMG) activity during the exercise. Methods: Twelve male participants, with at least five years of strength training experience, performed bench press exercises under two conditions: with extrinsic motivation (no specific focus on muscle activity) and with intrinsic motivation (internal focus on specific muscles). Surface electromyography (sEMG) was used to measure muscle activity during three sets of bench presses at 60% of one repetition maximum (1RM). Participants were instructed to focus on the activation of specific muscles in a randomized sequence. Results: The intrinsic motivation condition significantly increased muscle activation compared to extrinsic motivation. Electromyographic activity of the AD, PM, and TBL muscles was notably higher when participants focused their attention on these muscles. AD activation increased from 71.78 ± 11.13%MVC (extrinsic) to 88.03 ± 8.84%MVC (intrinsic) (p = 0.0019), while PM and TBL activation also demonstrated significant increases under intrinsic focus. Conclusions: The study concludes that intrinsic motivation, or an internal focus on specific muscle activation, can significantly enhance EMG activity in target muscles during the bench press exercise. This finding has important implications for resistance training and rehabilitation, where focused muscle activation can be utilized to improve training outcomes and muscle engagement.