Search Results (63)

Objectives: The present study aimed to investigate changes in forearm muscle activity associated with short-term go-kart driving (680 m) and its potential effect on muscle activation patterns. Methods: Eleven male karting league drivers (mean age: 23.18 ± 1.40 years; body mass: 83.27 ± 10.98 kg; height: 182.73 ± 5.66 cm) volunteered to participate. Electromyographic (EMG) activity was recorded from four muscles: extensor carpi radialis (ECR), extensor carpi ulnaris (ECU), flexor carpi radialis (FCR), and flexor carpi ulnaris (FCU). Baseline EMG was measured before the intervention, followed by two consecutive kart-driving sessions on a 680 m closed track. Post-exercise EMG data were then collected. A repeated-measures analysis of covariance (ANCOVA) was used to analyze the effects of time (pre vs. post) while controlling for cumulative race time as a covariate. Results: A significant time effect with cumulative time as a covariate was observed, particularly in the ECR and ECU muscles on both the left and right sides. Notable findings include increases in maximum and mean activity of the left and right ECR (e.g., ECR right max: F = 51.57; p < 0.001; η² = 0.851) and ECU (e.g., ECU right max: F = 36.170; p < 0.001; η² = 0.801). Additionally, a significant increase was found in the maximum activation of the left FCR (F = 11.019; p = 0.009; η² = 0.550, which remained significant after controlling for total driving time. This heightened activation likely reflects an acute neuromuscular fatigue response to the demands of kart steering, rather than a long-term adaptation. Conclusions: The findings suggest that even short bouts of kart driving can induce measurable changes in neuromuscular activation of the forearm muscles, particularly in those involved in grip control and steering stability. This highlights the physical demands of karting and its potential impact on the upper limb muscle conditioning. 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

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

Work-related musculoskeletal disorders (WMSDs) are common in the agricultural industry due to repetitive tasks, like plant transplanting, which involve sustained bending, squatting, and awkward postures. This study uses wearable sensors to evaluate human biomechanics during simulated transplanting and assesses the potential of collaborative robot (cobot) assistance to reduce physical strain. Sixteen participants performed transplanting tasks under manual and cobot-assisted conditions. Kinematic and electromyographic (EMG) data were collected using Xsens motion capture and Trigno EMG systems. Cobot assistance significantly reduced the segment velocity and acceleration in key spinal regions (L5/S1, L1/T12, T1/C7), indicating lower dynamic spinal loading. It also altered muscle activation, decreasing biceps brachii use while increasing activation in stabilizing muscles such as the flexor carpi radialis, brachioradialis, and upper trapezius. Task duration decreased by 59.46%, suggesting improved efficiency. These findings highlight cobots’ potential to enhance ergonomic outcomes by encouraging controlled movements and reducing postural stress. However, the shift in muscle activation underscores the need for task-specific cobot tuning. This research supports the use of integrated IMU and EMG systems to inform cobot design and enable real-time biomechanical monitoring in labor-intensive settings. Full article

Trapeziometacarpal joint osteoarthritis (TMJ OA) is a progressive condition, particularly affecting postmenopausal women. Various surgical techniques have been proposed, but the optimal approach remains debated. This clinical study compares the clinical, functional, and radiological outcomes of two surgical treatments: suspension tenoplasty using the flexor carpi radialis tendon (Altissimi technique, AST) and a dual-mobility prosthesis. The main complications associated with these procedures include postoperative pain, De Quervain’s syndrome, radial nerve injuries, and prosthetic component mobilization. In prosthetic arthroplasty, the most common complication is component mobilization (8%), while in tenoplasty, postoperative pain is the most frequent (15%). A total of 36 patients were randomized into two groups: 18 patients underwent AST (Group A), and 18 received trapeziometacarpal joint arthroplasty (Group B). Functional outcomes were assessed using the Disabilities of the Arm, Shoulder and Hand (DASH), Visual Analogue Score (VAS), and Michigan Hand Outcomes Questionnaire (MHQ) at 3, 6, 12, and 24 months. Range of motion (ROM), Kapandji score, pulp pinch strength, hand grip strength (Jamar dynamometer), and radiological maintenance of the trapezial space (step-off measurement) were also evaluated. Both procedures resulted in significant pain reduction (VAS, p < 0.05) and functional improvement (DASH, MHQ, p < 0.05). ROM increased significantly in both groups. The Kapandji scores improved from 4.0 ± 1.1 to 9.2 ± 1.2 (Group A) and 4.3 ± 0.8 to 7.8 ± 1.4 (Group B) (p < 0.05). Group B grip strength results showed a greater increase in hand grip strength than Group A (p = 0.23). The radiographic step-off showed slight proximal migration of the first metacarpal in Group A, whereas Group B maintained joint height. No implant loosening or major complications were reported in either group. Both suspension tenoplasty and dual-mobility arthroplasty are effective in TMJ OA. AST ensures joint stability with minimal radiographic changes, whereas TJA provides superior grip strength and ROM recovery. The absence of major complications suggests that TJA is a safe alternative to AST, but its higher cost and potential for implant-related complications must be considered. Full article

Background: Distal intersection tenosynovitis (DIT) is a rare and recently described condition that affects the extensor pollicis longus (EPL), extensor carpi radialis brevis (ECRB), and longus (ECRL). Based on surgical observations, this study aimed to provide new insights into its physiopathology. Methods: This was a retrospective study of all patients who underwent surgery for DIT at our institution from 2015 to 2024. Five patients were included in the study. Results: Wrist joint issues clearly explained the occurrence of DIT in three cases. Tendon lesions were observed either on the extensor carpi radialis brevis or extensor pollicis longus. Conclusions: These additional data complement the existing literature, which primarily focuses on the anatomical mechanisms of DIT without fully explaining its causes. Our observations suggest that wrist joint or bone disorders may play a significant role in its occurrence. Lesions in different tendons suggest the involvement of distinct pathological mechanisms. Full article

Background: This study reported a case of zone VII multiple neglected extensor tendons reconstruction with a palmaris longus tendon autograft in a 15-year-old boy 3 months after the initial trauma. Case presentations: Preoperative examinations revealed complete damage of the extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), abductor pollicis longus (APL), and partial injury of the extensor pollicis brevis (EPB). The extensor tendons were reconstructed with a palmaris longus tendon autograft combined with graft tunnel reconstruction within the scar at the level of the damaged retinaculum. After the surgical treatment, short immobilization and early rehabilitation were applied, providing passive sliding of the reconstructed tendon supplemented with actively mediated extension. Results: Despite the neglectful nature of the injury, surgical treatment and early postoperative rehabilitation resulted in an excellent functional outcome. At the follow-up visit, 6 months postoperative, the patient presented a full range of motion of the radiocarpal joint and thumb without any limitations on hand function. Conclusions: (1) Palmaris longus tendon autograft is a viable option for the treatment of multiple zone VII extensor tendon damage. (2) The combination of early passive motion and actively mediated extension provides tendon gliding and results in good functional outcomes for a hand with zone VII extensor tendon injury. (3) Ultrasound examination can evaluate early results and detect complications, mainly tendon/graft adhesions, after extensor tendon reconstruction surgery. Full article

Extensive studies have demonstrated the advantages of augmented reality (AR) in improving efficiency, thereby fulfilling a quality role in industry. Yet, the corresponding physical strain on individuals poses a significant challenge. This study explores the effects of task difficulty (complex versus simple maintenance activities) and multimedia guidance (e.g., paper-based versus AR via HoloLens) on physical strain, body discomfort ratings, perceived exertion, and mental effort. A 2 × 2 mixed design was employed, involving a total of 28 participants with an average age of 32.12 ± 2.45 years. Physical strain was evaluated by measuring the normalized root mean square (RMS) of electromyography (EMG) indicators, expressed as a percentage of maximum voluntary contraction (%MVC) from six muscles (i.e., right flexor carpi radialis (RFCR), right middle deltoid (RMD), right upper trapezius (RUT), right cervical extensor (RCE), and right and left splenius (RSPL and LSPL) muscles. The results indicated that AR instruction, particularly in complex tasks, led to higher physical strain in the neck and shoulder muscles (RCE and RUT) compared with paper-based methods. However, AR significantly reduced strain in the RSPL, LSPL, RMD, and RFCR muscles during both simple and complex tasks. This study highlights that while AR can lower physical strain in certain muscle groups, it also introduces increased strain in the neck and shoulders, particularly during more demanding tasks. This study highlights the need for ergonomic considerations when designing and implementing AR technologies, especially for complex tasks that inherently demand more from the user, both physically and cognitively. Full article

Background: Lateral epicondylitis impacts 1–3% of the population. It affects nearly half of all tennis players, primarily due to repetitive forearm muscle use leading to pain at the lateral elbow, particularly at the extensor carpi radialis brevis tendon. While conservative treatments resolve most cases, 4–11% of patients with persistent pain require surgery. Tenotomy is the gold standard for repair, but the research comparing the benefits of specific types of tenotomies (open, arthroscopic, percutaneous, ultrasonically assisted, and Tenex forms) is lacking. Methods: PubMed and Embase searches were conducted for articles focused on four tenotomy techniques. The inclusion criteria allowed for the use of randomized controlled trials (RCTs), prospective cohort studies, and comparative observational studies, while the exclusion criteria excluded meta-analyses. Following the PRISMA guidelines, the initial search resulted in 2327 articles. Once the inclusion and exclusion criteria were applied, 1702 articles underwent abstract screening. Finally, 232 articles proceeded to full-text screening, resulting in 37 articles undergoing data extraction. Results: The primary outcomes included functional improvement, pain relief, overall performance, and postoperative disability. The secondary outcomes included patient-reported satisfaction, return-to-work timeframes, and procedural complications. Conclusions: The tenotomy outcomes were similar, regardless of the method, indicating that discussions with patients about their specific outcome preferences may help guide tenotomy method selection. Full article

For the first time, we used an in vitro vs. in vivo experimental design to reveal core pathways under nitrogen deficiency (ND) in an evergreen tree crop. These pathways were related to lignin biosynthesis, cell redox homeostasis, the defense response to fungus, the response to Karrikin, amino acid transmembrane transport, the extracellular region, the cellular protein catabolic process, and aspartic-type endopeptidase activity. In addition, the mitogen-activated protein kinase pathway and ATP synthase (ATP)-binding cassette transporters were significantly upregulated under nitrogen deficiency in vitro and in vivo. Most of the MAPK downstream genes were related to calcium signaling (818 genes) rather than hormone signaling (157 genes). Moreover, the hormone signaling pathway predominantly contained auxin- and abscisic acid-related genes, indicating the crucial role of these hormones in ND response. Overall, 45 transcription factors were upregulated in both experiments, 5 WRKYs, 3 NACs, 2 MYBs, 2 ERFs, HD-Zip, RLP12, bHLH25, RADIALIS-like, and others, suggesting their ND regulation is independent from the presence of a root system. Gene network reconstruction displayed that these transcription factors participate in response to fungus/chitin, suggesting that nitrogen response and pathogen response have common regulation. The upregulation of lignin biosynthesis genes, cytochrome genes, and strigalactone response genes was much more pronounced under in vitro ND as compared to in vivo ND. Several cell wall-related genes were closely associated with cytochromes, indicating their important role in flavanols biosynthesis in tea plant. These results clarify the signaling mechanisms and regulation of the response to nitrogen deficiency in evergreen tree crops. Full article

Background: The study aimed to evaluate the immediate effect of Heat-Compression-Therapy with Game Ready equipment (GR-HCT) on biomechanical properties at different treatment times. Reducing the duration of stimulation through HCT can help optimize recovery processes in sports. Methods: Twenty male MMA fighters (26.5 ± 4.5 years, BMI 24.75 ± 3.0, training experience: 10.3 ± 5.0 years) performed two experimental sessions: (a) 5 min heat-compression therapy (HCT) stimulation (GR-HCT-5); and (b) 10 min heat-compression therapy (GR-HCT-10). All registered parameters, tissue perfusion (PU), tissue temperature (°C), muscle tone (T-Hz) stiffness (S—N/m), elasticity (E—arb), pressure pain threshold (PPT—N/cm) and isometric muscle strength (Fmax—kgf), were measured at rest (r—2 min before GR-HCT stimulation) and 1 min after GR-HCT (p-post) for the flexor carpi radialis muscle (MFCR) and the brachioradialis muscle (MBR). Results: The Friedman’s test for MBR revealed significant differences between GR-HCT5min vs. GR-HCT10min for PU (p < 0.0001), S (p = 0.008), and for MBR and MFCR for °C (p < 0.0001). The pairwise comparisons for PU, S, and °C showed significant differences between rest vs. post values for 5 min as well as between rest vs. post values for 10 min. Further, there was a significant interaction effect (5 min-10 min × Rest-Post p < 0.0001) for PU for MFCR. The post hoc comparison for the interaction effect showed significantly higher PU for post- compared to premeasurement in 5 min PU and 10 min PU (p < 0.001). Further, there was a significant main effect of condition for Fmax both for MFCR and MBR (5 min vs. 10 min p < 0.001); The post hoc comparison for the main effect of condition showed a significantly higher Fmax for post- compared to premeasurement in 5 min and 10 min (p < 0.001). Further, there was a significant main effect of condition for pressure pain threshold [N/cm] both for MFCR and MBR and for T for MBR time of measurement rest vs. post (p < 0.001; p = 0.006; p < 0.001, respectively). The post hoc comparison for the interaction effect showed a significantly lower PPT for post vs. rest in 5 min (p < 0.001 only for MFCR) and in 10 min (p < 0.001). The delta values for PU (post-rest) and ΔTemp °C showed significant differences between the 5 min and 10 min conditions (MFCR; p < 0.0001); (MBR p < 0.001) and (MFCR p < 0.0001); (MBR p < 0.001). Conclusion: Our results show that GR-HCT significantly affects recovery of muscle biomechanical parameters, pain threshold, strength, tissue perfusion, and temperature. Our findings show that a 5 min effect can be sufficient when compared to a 10 min one which is a clue for designing effective recovery protocols. Full article

A novel combination of variations involving the extensor carpi radialis (ECR) muscle group was observed bilaterally in a 75-year-old female cadaver during routine dissection. An accessory tendon was observed arising from the extensor carpi radialis longus (ECRL) and traveling with the primary tendon through the second compartment of the extensor retinaculum. While the primary tendon inserted on the base of the second metacarpal, as is typical of ECRL, the accessory tendon inserted on the base of the third metacarpal. This insertion is typical of the extensor carpi radialis brevis (ECRB) muscle. Additionally, bilateral agenesis of the ECRB was reported. Thirty-two additional forearms were assessed for similar variations, with none being observed. This combination of variations adds to the literature regarding the ECR muscle group, while also being of interest to clinicians, specifically regarding tendon reconstructive procedures as well as accessing the distal radial artery via the anatomical snuffbox. Full article

Modular control of the muscle, which is called muscle synergy, simplifies control of the movement by the central nervous system. The purpose of this study was to explore the synergy in both the frequency and movement domains based on the non-negative Tucker decomposition (NTD) method. Surface electromyography (sEMG) data of 8 upper limb muscles in 10 healthy subjects under wrist flexion (WF) and wrist extension (WE) were recorded. NTD was selected for exploring the multi-domain muscle synergy from the sEMG data. The results showed two synergistic flexor pairs, Palmaris longus–Flexor Digitorum Superficialis (PL-FDS) and Extensor Carpi Radialis–Flexor Carpi Radialis (ECR-FCR), in the WF stage. Their spectral components are mainly in the respective bands 0–20 Hz and 25–50 Hz. And the spectral components of two extensor pairs, Extensor Digitorum–Extensor Carpi Ulnar (ED-ECU) and Extensor Carpi Radialis–Brachioradialis (ECR-B), are mainly in the respective bands 0–20 Hz and 7–45 Hz in the WE stage. Additionally, further analysis showed that the Biceps Brachii (BB) muscle was a shared muscle synergy module of the WE and WF stage, while the flexor muscles FCR, PL and FDS were the specific synergy modules of the WF stage, and the extensor muscles ED, ECU, ECR and B were the specific synergy modules of the WE stage. This study showed that NTD is a meaningful method to explore the multi-domain synergistic characteristics of multi-channel sEMG signals. The results can help us to better understand the frequency features of muscle synergy and shared and specific synergies, and expand the study perspective related to motor control in the nervous system. Full article

Background: Chronic lateral epicondylitis challenges the therapeutical approach; underlying mechanisms are incompletely understood; neuropathic pain and central and peripheral sensitization may explain the fact that botulinum toxin has been found to play a role in pain and function management. Methods: We searched the literature for MeSH terms: lateral epicondylitis or synonyms and botulinum toxin. Results: We found 14 papers containing trials on botulinum toxin injection into the tendon or into the extensor muscles (specifically, extensor carpi radialis brevis and extensor communis digitorum). We followed the administration pathways, doses, timing, and side effects. Conclusions: With a chronic course, the focus of the therapy shifts from the afflicted tendon to the inserting muscles, as muscle contracture may create a vicious loop to perpetuate and aggravate the disease. Doses, timing, and side effects are discussed. Full article

Physiologic hand tremors are a critical factor affecting the aim of air pistol shooters. However, the extent of the effect of hand tremors on shooting performance is unclear. In this study, we aim to explore the relationship between hand tremors and shooting performance scores as well as investigate potential links between muscle activation and hand tremors. In this study, 17 male air pistol shooters from China’s national team and the Air Pistol Sports Center were divided into two groups: the elite group and the sub-elite group. Each participant completed 40 shots during the experiment, with shooters’ hand tremors recorded using three-axis digital accelerometers affixed to their right hands. Muscle activation was recorded using surface electromyography on the right anterior deltoid, posterior deltoid, biceps brachii (short head), triceps brachii (long head), flexor carpi radialis, and extensor carpi radialis. Our analysis revealed weak correlations between shooting scores and hand tremor amplitude in multiple directions (middle-lateral, ML: r² = −0.22, p < 0.001; vertical, VT: r² = −0.25, p < 0.001), as well as between shooting scores and hand tremor complexity (ML: r² = −0.26, p < 0.001; VT: r² = −0.28, p < 0.001), across all participants. Notably, weak correlations between shooting scores and hand tremor amplitude (ML: r² = −0.27, p < 0.001; VT: r² = −0.33, p < 0.001) and complexity (ML: r² = −0.31, p < 0.001) were observed in the elite group but not in the sub-elite group. Moderate correlation were found between the biceps brachii (short head) RMS and hand tremor amplitude in the VT and ML directions (ML: r² = 0.49, p = 0.010; VT: r² = 0.44, p = 0.025) in all shooters, with a moderate correlation in the ML direction in elite shooters (ML: r² = 0.49, p = 0.034). Our results suggest that hand tremors in air pistol shooters are associated with the skill of the shooters, and muscle activation of the biceps brachii (long head) might be a factor affecting hand tremors. By balancing the agonist and antagonist muscles of the shoulder joint, shooters might potentially reduce hand tremors and improve their shooting scores. Full article