Search Results (124)

Background/Objectives: This study aims to investigate the effects of caffeinated chewing gum on maximal strength, muscular power, and neural drive to the prime movers during bench press and back squat in resistance-trained men. Methods: Sixteen resistance-trained males participated in a double-blind, randomized trial, chewing either caffeinated gum (4 mg/kg) or placebo gum on two separate occasions, seven days apart. After chewing for 5 min, participants performed a maximal strength test followed by muscular power assessments at 25%, 50%, 75%, and 90% of their one-repetition maximum (1RM), completing with 3, 2, 1, and 1 repetition (s), respectively, for bench press and back squat. Surface electromyography data were recorded for each repetition. Results: Caffeinated gum did not significantly improve one-repetition maximum (1RM) for bench press (p > 0.05), but increased mean frequency (MF) and median frequency (MDF) in anterior deltoid, pectoralis major, and biceps brachii (all p < 0.05) compared to placebo. For back squat, 1RM increased with caffeinated gum, along with higher MF and MDF in vastus medialis (all p < 0.05). Caffeinated gum also improved mean and peak velocities, and mean and peak power outputs at 25–75% 1RM during the bench press (all p < 0.05), along with elevated MDF in pectoralis major and biceps brachii (all p < 0.05). Similar improvements were seen in mean and peak velocities during the back squat at 25–90% 1RM (all p < 0.05), along with higher MF and MDF in vastus medialis and increased normalized root mean square activity in gluteus maximus (all p < 0.05). Conclusions: Caffeinated chewing gum (4 mg/kg) enhanced muscular power (25–75% 1RM) in the bench press and improved maximal strength and muscular power (25–90% 1RM) in the back squat by increasing muscle recruitment in resistance-trained men. Full article

Introduction: We developed a computed tomography (CT)-based tool designed for automated segmentation of deltoid muscles, enabling quantification of radiomic features and muscle fatty infiltration. Prior to use in a clinical setting, this machine learning (ML)-based segmentation algorithm requires rigorous validation. The aim of this study is to conduct shoulder expert validation of a novel deltoid ML auto-segmentation and quantification tool. Materials and Methods: A SwinUnetR-based ML model trained on labeled CT scans is validated by three expert shoulder surgeons for 32 unique patients. The validation evaluates the quality of the auto-segmented deltoid images. Specifically, each of the three surgeons reviewed the auto-segmented masks relative to CT images, rated masks for clinical acceptance, and performed a correction on the ML-generated deltoid mask if the ML mask did not completely contain the full deltoid muscle, or if the ML mask included any tissue other than the deltoid. Non-inferiority of the ML model was assessed by comparing ML-generated to surgeon-corrected deltoid masks versus the inter-surgeon variation in metrics, such as volume and fatty infiltration. Results: The results of our expert shoulder surgeon validation demonstrates that 97% of ML-generated deltoid masks were clinically acceptable. Only two of the ML-generated deltoid masks required major corrections and only one was deemed clinically unacceptable. These corrections had little impact on the deltoid measurements, as the median error in the volume and fatty infiltration measurements was <1% between the ML-generated deltoid masks and the surgeon-corrected deltoid masks. The non-inferiority analysis demonstrates no significant difference between the ML-generated to surgeon-corrected masks relative to inter-surgeon variations. Conclusions: Shoulder expert validation of this CT image analysis tool demonstrates clinically acceptable performance for deltoid auto-segmentation, with no significant differences observed between deltoid image-based measurements derived from the ML generated masks and those corrected by surgeons. These findings suggest that this CT image analysis tool has potential to reliably quantify deltoid muscle size, shape, and quality. Incorporating these CT image-based measurements into the pre-operative planning process may facilitate more personalized treatment decision making, and help orthopedic surgeons make more evidence-based clinical decisions. Full article

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

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

The Inverted Swallow (IS) is a rare isometric upper-body skill in artistic gymnastics. Athletes use Preconditioning Strengthening Exercises (PSEs) to develop the strength necessary to hold the IS at competition rings. However, the specific muscle excitation and synergies typical of the IS and its PSEs remain unexplored. Thus, this study analyzed muscle excitations and synergies during the IS and its five common PSEs. Muscle excitation was recorded from the pectoralis major, latissimus dorsi, triceps brachii, infraspinatus, trapezius, serratus anterior, biceps brachii and posterior deltoid muscles in six elite calisthenics athletes (age: 24.5 ± 3.0 years; height: 168.6 ± 5.8 cm; body mass: 65.0 ± 4.7 kg). Non-Negative Matrix Factorization was used to extract synergies. The results showed a predominant role of the posterior deltoid and triceps brachii during the IS. Significant differences were observed in the muscle excitation of the triceps brachii between the IS and its PSEs (p ≤ 0.001; W = 0.765), and in the posterior deltoid (p = 0.002; W = 0.629). Muscle synergy patterns also differed in simultaneous muscle activation between the IS and its PSEs. These findings provide the first detailed evidence of the characteristics of the IS element, providing insights for optimizing strength training and gymnastics performance. Full article

Fire extinguisher inspectors face ergonomic risk factors and are exposed to several musculoskeletal disorders (MSDs). The aim of this study was to design and evaluate a mobile lift device to reduce the risk of musculoskeletal injuries among fire extinguisher inspectors. This was followed by a quasi-experimental trial among 28 workers, using surface electromyography (EMG), in which muscle activity with percentage of maximum voluntary contraction (MVC), postural analysis using the Rapid Entire Body Assessment (REBA), perceived exertion, and perceived ease of use among workers were evaluated during the fire extinguisher inspection process employing a manual fire extinguisher and using a mobile lift device. The results of the EMG measurement of the muscle activity in the biceps brachii, triceps brachii, middle deltoid, and upper trapezius were obtained using the MVC parameter. The MVC parameter was employed to normalize the EMG signals, allowing for a standardized comparison of muscle activation levels across different tasks and conditions. The results showed a significant positive effect on the muscle activity of the middle deltoid and biceps brachii; the posture risk level and rating for perceived exertion with the mobile lift device were generally lower than those of manual lifting (p < 0.001). With the mobile lift device, there was significant reduction in the muscle activity of the triceps brachii and upper trapezius (p < 0.05). Accordingly, mobile lift devices were found to be useful due to the reduced muscle effort, and postural risks were reduced when using the mobile lift device. Further studies are needed for modifications to the lift assist device based on ergonomic measures of muscle activity and user tests by adjusting the task to suit the capabilities of workers. Full article

Background/Objectives: Clinicians have employed various therapeutic exercises to enhance the function and strength of the subscapularis muscle (SSC). However, few studies have investigated the most effective exercise for selectively activating the SSC while minimizing compensation from surrounding shoulder musculatures. Methods: Forty healthy participants without any shoulder complex conditions participated in this study. Individuals with a history of shoulder pain or musculoskeletal or neurological conditions affecting shoulder internal rotation were excluded. Participants performed three exercises: (1) Belly Press, (2) Lift Off, and (3) Prone Wiper, in a randomized order generated using Microsoft Excel. Ultrasound was then performed to assess the SSC and infraspinatus (IS) muscle thickness. Surface electromyography was used to record anterior deltoid (AD), pectoralis major (PM), and posterior deltoid (PD) muscle activity. Radiographic imaging was employed to evaluate the path of the instantaneous center of rotation (PICR). Data were analyzed using a one-way repeated-measures analysis of variance (ANOVA), followed by Bonferroni adjustment. Results: A significant reduction in IS thickness and PICR was observed only following the Belly Press (p < 0.05). Electromyographic activity of AD, PM, and PD increased significantly across all exercises (p < 0.05). These results demonstrate that the Belly Press most effectively allows the SSC to generate force while maintaining a stable center of rotation during shoulder movement. Conclusions: The Belly Press was most effective in selectively activating the SSC while minimizing surrounding shoulder rotator muscle activity and reducing PICR. This finding may help clinicians identify and treat patients with shoulder internal rotation injuries. Full article

Ultrasound-guided botulinum toxin type A (BoNT-A) injections play a critical role in the management of upper limb spasticity. This is the second part of ‘The Elias University Hospital Approach: A Visual Guide to Ultrasound-Guided Botulinum Toxin Injection in Spasticity’ and it focuses on the proximal upper limb muscles, complementing the first part, which addressed the distal upper limb muscles. This guide provides a detailed analysis of ultrasound anatomy, clinical relevance, and injection strategies for the latissimus dorsi, teres major, subscapularis, pectoralis major, pectoralis minor, deltoid, triceps brachii, biceps brachii, brachialis, and brachioradialis. Using the Elias University Hospital (EUH) model, it presents a structured approach to BoNT-A administration, ensuring precision, safety, and optimal outcomes in spasticity management. To enhance clinical application, this guide incorporates a wide array of high-quality ultrasound images and dynamic videos, offering a comprehensive and practical understanding of scanning techniques, anatomical structures, and injection procedures. This second part of the series serves as an essential reference for clinicians, aligning with the first installment to provide a complete and systematic approach to ultrasound-guided BoNT-A therapy for upper limb spasticity. Full article

Background: Vaccine hesitancy (VH) is a significant public health challenge, especially during the COVID-19 pandemic. Despite extensive research on the psychological and socio-political determinants of VH, its psychophysiological mechanisms remain unexplored. Grounded in the Somatic Marker Hypothesis, this study aims to investigate the neurophysiological and affective processes underlying VH. Methods: Two experiments will assess sensorimotor resonance and affective processes in VH. In the first experiment, motor-evoked potentials (MEPs) will be recorded from the deltoid and extensor carpi radialis muscles while participants view images of people receiving COVID-19 and influenza vaccines, as well as blood injections (Block 1), and images of vial containing the same substances (Block 2). Facial electromyographic (EMG) activity will measure disgust and fear responses. In the second experiment, skin conductance response (SCR) will be recorded during a virtual reality-based fear conditioning and extinction paradigm. Expected Outcomes: We hypothesize that vaccine-hesitant individuals will exhibit altered sensorimotor resonance, higher affective responses to vaccination stimuli, and impaired fear extinction learning. Psychological traits such as disgust sensitivity, paranoia, anxiety, and dogmatism are expected to be associated with VH. Conclusions: By identifying the psychophysiological mechanisms of VH, this study will contribute to developing effective vaccine promotion strategies to address future public health emergencies. Full article

Background/Objectives: The combination of a hemagglutinin antigen (HA)-based inactivated influenza vaccine (IIV; Fluarix^® Tetra; GlaxoSmithKline) with a nucleoprotein (NP)-based vaccine, such as OVX836, should increase the efficacy of influenza vaccines since it leverages two complementary immunological mechanisms: HA antibodies targeting the virus envelope and neutralizing it, and an NP cell-mediated immune (CMI) response destroying infected cells. Methods: This was a randomized, double-blind, Phase 2a study (ClinicalTrials.gov NCT05284799) including three groups of 60 healthy subjects (18–55 years old) receiving either IIV + placebo, IIV + OVX836 (480 µg), or OVX836 + placebo intramuscularly and concomitantly into the same deltoid muscle. The endpoints were reactogenicity, safety, and immunogenicity (hemagglutination inhibition assay [HAI], anti-NP immunoglobulin G [IgG], and NP-specific cell-mediated immunity [CMI]). Results: The co-administration of IIV + OVX836 was safe and well-tolerated. The HAI response was strong and similar in the two IIV groups with no interference of OVX836. The humoral anti-NP IgG and NP-specific CMI responses to OVX836 were strong in the two OVX836 groups, and no major interference of IIV was observed. Conclusions: This study supports further clinical development of OVX836 as a combined IIV/OVX836 seasonal vaccine capable of inducing robust and complementary HAI and CMI NP-specific responses. Full article

Both for design issues and for the study, analysis, and understanding of the interaction of workers with exoskeletons, the study of adverse effects provides criteria to improve the design of more efficient exoskeletons with better ergonomics and long-term usability. In this work, a scoping review was carried out on adverse effects due to the prolonged use of upper-limb exoskeletons, which have been evidenced in the scientific literature. The causes of the effects are described in terms of their impacts on the physiological, psychological, and technological aspects that affect the user. A scoping review of articles of the last ten years on negative effects of upper-extremity exoskeletons for industrial tasks was carried out following the guidelines of the PRISMA^® methodology with three phases: formulation of questions, definition of scopes and exhaustive search in SCOPUS, Web of Science, Science Direct, Taylor & Francis, and PubMed. The selection was made by two review authors with a Cohen’s Kappa coefficient of 0.9530, indicating high agreement. The effectiveness of upper-limb exoskeletons depends on the environment and the task, so an adaptable ergonomic design, field validations, and standards are required to ensure their functionality and acceptance. Use of exoskeletons mainly activates the posterior deltoid and latissimus dorsi and reduces the activity of muscles such as the trapezius, pectoralis major, anterior and middle deltoids, biceps brachii, brachioradialis, and flexor carpi radialis. Full article

Objectives: This study aimed to compare the acute responses of the muscular activity of primary movers during bench press execution under asymmetric loads (25%, 50%, and 75%). Methods: The study included 30 resistance-trained males (n = 25, age = 22.73 ± 3.44 years, height= 1.77 ± 0.06 m, body mass= 76.77 ± 9.28 kg) and females (n = 5, age = 22.5 ± 1.19 years, height = 1.63 ± 0.04 m, body mass = 56.78 ± 2.90 kg). We assessed the two portions of the dominant pectoralis major, triceps brachii, anterior deltoid, and both external oblique peak activities (sEMG) during concentric and eccentric phases. We performed a repeated-measures design to establish the differences between muscle activity, barbell center of mass acceleration, and OMNI-Perceived Exertion Scale for Resistance Exercise (OMNI-RES) in a bench press under seven different conditions. Results: The linear mixed model showed a significant fixed effect for exercise condition for muscles (p < 0.001) in the concentric and eccentric phases. We found significantly higher clavicularis (d = 0.54; d = 1.15) and sternalis (d = 0.38; d = 0.86) pectoralis major activation of the dominant side under high (50% and 75%), non-dominant-side, de-loaded conditions in the eccentric phase (p < 0.001), with large effects. Contralateral core muscles (external oblique) of the dominant and non-dominant sides were significantly (p < 0.001) highly activated under all asymmetric conditions in the concentric phase (from d = 0.89 to d = 2.30). Conclusions: The asymmetric load bench press provoked a higher pectoralis major activation on the loaded side when de-loading the other side. The contralateral external oblique doubles the muscle activity in the most asymmetric conditions. Full article

This study investigated kinetic and physiological load characteristics of Self-Manual Resistance Training (SMRT) lat pulldown. SMRT lat pulldown is a training method in which practitioner generates resistance manually using their own muscular force by gripping a towel with both hands and pulling it outward in a horizontal direction. We analyzed shoulder and elbow joint moments in frontal plane (2D) and muscle activity levels of latissimus dorsi (LD), posterior deltoid (PD), biceps brachii (BB), and triceps brachii (TB) during 10 maximal-effort repetitions of SMRT lat pulldown in 11 resistance-trained men. For comparison, we also measured muscle activity levels during a machine lat pulldown for 10 reps at 75% 1 RM load in same participants. Peak shoulder adduction and elbow extension moments during SMRT lat pulldown were both approximately 70% MVC. Mean rectified EMG of LD was significantly greater during machine lat pulldown than SMRT lat pulldown, whereas that of PD was significantly greater during SMRT than machine version. Mean rectified EMG of TB was high during SMRT, and that of BB was high in machine version. SMRT lat pulldown appears to produce relatively large shoulder adduction and elbow extension moments, increasing PD and TB activation and limiting LD activation. Full article

Background/Objectives: This study aimed to analyze the psychophysiological effects of functional neurology intervention on dysfunction in vestibular saccadic stimuli, focusing on its impact on muscle performance, psychophysiological arousal, and pain perception. Methods: Seventy-five healthy volunteer participants were randomly divided into two groups: an experimental group that received functional neurology treatment and a control group that did not. Both groups underwent the same evaluations at four distinct time points. Key measurements included pressure pain threshold (PPT), hand strength, critical flicker fusion threshold (CFFT), blood oxygen saturation, heart rate, and the number of saccadic stimuli tolerated until dysfunction in an indicator muscle (anterior deltoid). The functional neurology intervention involved proprioceptive reflexes, trigger point desensitization, and systemic approaches to rectify neuromuscular dysfunctions. Results: The results showed that the functional neurology intervention significantly increased the number of saccadic stimuli tolerated, from 3.6 ± 3.3 to 26.1 ± 8.7, indicating an improvement in neuromuscular endurance. Additionally, PPT readings exhibited an upward trend from baseline to post-intervention, with the final reading averaging at 10.2 ± 5.3 kgf, and hand strength measurements showed a modest but significant increase post-intervention. Notably, CFFT and blood oxygen saturation levels remained relatively stable, suggesting that the intervention’s primary impact was on neuromuscular performance and pain perception rather than on cognitive arousal or systemic oxygenation. Heart rate data indicated a decrease post-intervention, implying potential improvements in autonomic nervous system function. In contrast, the control group did not present significant changes in any of the psychophysiological parameters evaluated. These findings underscore the potential of targeted functional neurology treatments to enhance physical performance and provide valuable therapeutic benefits for neuromuscular and cognitive dysfunctions. Conclusions: Functional neurology interventions can effectively improve muscle endurance, pain management, and overall neuromuscular health, highlighting its relevance as a therapeutic modality in sports performance optimization and rehabilitation contexts. Full article

Background and Objectives: Scapular muscles are crucial in controlling scapular movement, ensuring proper alignment, and preventing injuries during shoulder joint motion. The shoulder abduction angle is one of the most important factors when performing exercises to improve scapular movement control. The Pilates reformer arm work (AW) movement can be performed with different shoulder abduction angles. Therefore, this study analyzed the differences in scapular muscle activation depending on the shoulder abduction angle during the AW movement. Materials and Methods: Twenty-six healthy adult males performed the AW movement under four shoulder abduction angle conditions (0°, 90°, 135°, 160°). When performing the AW in the four conditions, surface electromyography analyzed the muscle activation of the upper trapezius (UT), middle trapezius (MT), lower trapezius (LT), serratus anterior (SA), posterior deltoid (PD), and levator scapulae (LS), and the muscle activation ratios of the UT/LT, LS/LT, UT/SA, and LS/SA. Results: The UT, LT, and SA muscle activation increased proportionally with the increasing shoulder abduction angle (p < 0.001). The LT showed the highest muscle activity at the shoulder abduction angle of 135° (p < 0.001). The MT and PD showed the highest muscle activities at the shoulder abduction angle of 90° (p < 0.001). The muscle activity ratios of the UT/LT and LS/LT were the lowest at the shoulder abduction angles of 90° and 135° (p < 0.001). The muscle activity ratio between the UT/SA and LS/SA was the lowest at the 135° and 160° shoulder abduction angles (p < 0.001). Conclusions: Our findings highlight the impact of the shoulder abduction angle on scapular muscle activation, suggesting that different angles may be used to engage specific muscles during Pilates reformer arm work exercises selectively. This insight can guide exercise interventions for individuals aiming to improve their scapular control and stability. Full article