Search Results (5,294)

This study investigates occupant–seat interaction dynamics in high-speed train frontal collisions. A finite element model of a second-class double seat was developed and simulated using LS-DYNA R12.1 software with a Hybrid III dummy, applying trapezoidal and triangular acceleration pulses per European and American standards. The research analyzes the impact of front-row seatback recline angles (0°, 10°, 20°) and seatback-to-base connection stiffness (1000 N/mm to 0 N/mm) on head, neck, chest, and leg injury severity. Results show that a 10° recline provides optimal protection under fixed stiffness. When optimizing both parameters, a 0° recline with approximately 300 N/mm stiffness minimizes composite injury metrics (HIC₁₅, N_ij, CTI). However, reducing stiffness at non-zero recline angles increases neck injury risk due to tray table displacement toward the cervical region. These findings emphasize the critical importance of integrated seat design optimization for rail passenger passive safety and highlight the need to mitigate tray table hazards. Full article

Background and Objectives: Frail patients after open-heart surgery often experience worse treatment outcomes in improving physical performance and muscle strength. As the functional recovery of frail patients after open-heart surgery is slower, conventional rehabilitation is frequently insufficient to achieve treatment goals. Therefore, the inclusion of additional exercise interventions in cardiac rehabilitation is becoming more relevant. The aim of this study was to assess and compare the effectiveness of additional exercise interventions—multicomponent and computer-based programs—applied along with conventional cardiac rehabilitation in improving the functional capacity and strength of frail patients after open-heart surgery. Materials and Methods: The population of this single-center, three-arm, parallel-group, randomized controlled trial comprised 153 frail patients aged more than 65 years who underwent open-heart surgery. All patients were randomized into three groups: control (CG, n = 51), intervention 1 (IG-1, n = 51), and intervention 2 (IG-2, n = 51). All groups received conventional rehabilitation program six times/week, while the IG-1 additionally received the multicomponent dynamic training program 3 times/week, and the IG-2, the combined computer-based program 3 times/week. The primary outcome measure was change in the Short Physical Performance Battery (SPPB) score. Secondary outcome measures included the 6 min walk distance (6MWD), peak workload, grip strength, and leg press. Primary and secondary outcome measures were assessed before and after cardiac rehabilitation. Results: A total of 138 patients completed rehabilitation (46 in each group), and their data were included in the main analysis that followed a per-protocol approach. Although significant differences in the primary outcome—the SPPB score—were found in each group while performing within-group comparisons (p < 0.001), no significant pre-to-post rehabilitation differences were observed compared to all three groups (p = 0.939), and the effect sizes were small. Regarding secondary outcome measures, within-group comparison revealed significant differences in all parameters of all groups (p < 0.05), except for the grip strength of both hands in the IG-1. Between-group comparisons showed that the pre-to-post 6MWD difference between the CG and the IG-1 was significant (p = 0.014), but the effect size was small (ES = 0.240). Moreover, significant pre-and-post leg press 1RM differences (p < 0.001) were found between the CG and the IG-1 as well as between the CG and the IG-2 with the effect sizes being moderate (ES = 0.480) and large (ES = 0.613), respectively. Conclusions: Within-group comparison showed that all three rehabilitation programs are effective in improving almost all parameters of physical performance and muscle strength in frail patients after open-heart surgery. However, between-group comparisons indicated that computer-based interventions were more effective in improving leg press 1RM with a large effect size, while multicomponent training resulted in more effective gains in the 6MWD, although with a small effect size. These findings suggest that in clinical practice, computer-based exercise programs may be more suitable for patients with muscle weakness, while multicomponent exercise programs may be for those with reduced endurance. Full article

Cognitive tasks play a pivotal role in posture control among young adults. This study examined how concurrent cognitive tasks alter balance stability and sensory integration during single-leg stance by analyzing center-of-pressure trajectories and wavelet spectra to elucidate the neurobehavioral mechanisms underlying dual-task balance degradation. A cohort of 24 young adults completed both single postural control tasks and dual cognitive–postural tasks on a force plate. COP data and wavelet decomposition energy were computed and analyzed. The results revealed significant differences between the dual-task and single-task groups for Lxy, Ly, Vxy, and Vy (p < 0.05). Energy content analysis showed that the dual-task group had significantly different energy ratios across four frequency bands along the x-axis (p < 0.05). Our findings showed that dual-task conditions impair postural control in young adults, increasing anteroposterior sway and altering mediolateral energy patterns. This suggests a shift toward proprioceptive reliance during cognitive division, revealing cognitive–postural interference. These results support using dual-task assessments for fall risk evaluation and inform interventions for populations requiring cognitive–motor integration. Full article

Background/Objective: Understanding the training effect in high-level running is important for performance optimization and injury prevention. This includes awareness of how different running surface types (e.g., hard versus soft) may modify biomechanics. Recent studies have demonstrated that deep learning algorithms, such as convolutional neural networks (CNNs), can accurately classify human activity collected via body-worn sensors. To date, no study has assessed optimal signal type, sensor location, and model architecture to classify running surfaces. This study aimed to determine which combination of signal type, sensor location, and CNN architecture would yield the highest accuracy in classifying grass and asphalt surfaces using inertial measurement unit (IMU) sensors. Methods: Running data were collected from forty participants (27.4 years + 7.8 SD, 10.5 ± 7.3 SD years of running) with a full-body IMU system (head, sternum, pelvis, upper legs, lower legs, feet, and arms) on grass and asphalt outdoor surfaces. Performance (accuracy) for signal type (acceleration and angular velocity), sensor configuration (full body, lower body, pelvis, and feet), and CNN model architecture was tested for this specific task. Moreover, the effect of preprocessing steps (separating into running cycles and amplitude normalization) and two different data splitting protocols (leave-n-subject-out and subject-dependent split) was evaluated. Results: In general, acceleration signals improved classification results compared to angular velocity (3.8%). Moreover, the foot sensor configuration had the best performance-to-number of sensor ratio (95.5% accuracy). Finally, separating trials into gait cycles and not normalizing the raw signals improved accuracy by approximately 28%. Conclusion: This analysis sheds light on the important parameters to consider when developing machine learning classifiers in the human activity recognition field. A surface classification tool could provide useful quantitative feedback to athletes and coaches in terms of running technique effort on varied terrain surfaces, improve training personalization, prevent injuries, and improve performance. Full article

The aim of this study was to explore the prevalence of acute and overuse injuries, as well as risk factors, training load and well-being, in male and female youth padel players. Using a cross-sectional design, data were collected from 104 players (aged 15–20) via a web-based form. Players reported injuries, exposure and rating of perceived exertion (RPE), demographics (age and sex), and perceived well-being. Overuse injury severity was scored per body region (0–25), yielding a total possible score of 125. A total of six acute and 49 overuse injuries were recorded, corresponding to a prevalence of 0.53 injuries per player during a one-week recall period. Most injuries affected the knee, while the foot and lower leg had the highest severity scores (median = 44). Female players reported slightly higher stress levels (median 3) than males (median 2: p = 0.01), though no other well-being or training load differences were found. Injured players had significantly higher total wellness scores, indicating worse well-being, compared to non-injured players (median 10 vs. 9, p = 0.03). In conclusion, overuse injuries, particularly to the knee, were most common. Higher perceived stress and poorer wellness scores may be linked to injury risk, underlining the importance of monitoring well-being in youth padel athletes. Full article

Background: Postural control in healthy young adults involves complex neuromuscular processes; however, the kinematic and kinetic consequences of small, forward leg perturbations in a defined population are not fully described. This study aimed to characterize the kinematic and kinetic consequences of forward leg perturbations during quiet standing. Methods: This investigation used a quasi-experimental repeated-measures design. Sixteen healthy young women (20.1 ± 0.7 years), all right-leg dominant, were tested using the Gait Real-Time Analysis Interactive Laboratory (GRAIL) system. Forward treadmill perturbations were applied to each limb during quiet standing, and joint angles, ground reaction forces, and torques were measured across baseline, perturbation, and response phases. As the data were non-normally distributed, paired comparisons were conducted using the Wilcoxon test, with significance set at p < 0.05 (Bonferroni corrected) and effect sizes (r) reported. Results: Joint angles remained symmetrical between limbs (no significant differences after correction). In contrast, kinetic measures showed clear asymmetries: at baseline, the dominant limb produced greater knee torque (p = 0.0003, r = 0.73), ankle torque (p = 0.0003, r = 0.76), and medio-lateral GRF (p = 0.0003, r = 0.87). During perturbation, it again generated higher knee (p = 0.0036, r = 0.43) and ankle torques (p = 0.0003, r = 0.53), with larger medio-lateral GRF (p = 0.0003, r = 0.87). In the response phase, the dominant limb showed greater hip torque (p = 0.0033, r = 0.43) and a small dorsiflexion shift at the ankle (p = 0.0066, r = 0.41). Anterior–posterior GRF changes were minor and non-significant after correction. Conclusions: Induced forward leg movements caused limb-specific kinetic adjustments while maintaining overall kinematic symmetry. The dominant leg contributed more actively to balance recovery, highlighting its role in stabilizing posture under small perturbations. These findings are specific to the studied demographic and should not be generalized to males, older adults, left-dominant individuals, or clinical populations without further research. Full article

Introduction: Nowadays, there is evidence regarding a beneficial effect of heat on neuromuscular strength and muscle hypertrophy development. The aim of this study is to evaluate the effects of a 4-week passive sauna bathing program to extreme heat (100 ± 2 °C) as a support for a resistance strength training program on maximal strength and body composition. Methods: 30 young male subjects participated in the study. They were randomly assigned to a Hyperthermia group (HG, n = 14; age: 20.48 (19.12–22–30) years; weight: 76.30 (71.00–79.00) Kg; BMI: 23.92 (22.93–24.87) Kg/m²), or to a Normothermia group (NG, n = 15; age: 19.95 (19.10–21–94) years; weight: 61.70 (59.45–72.90) Kg; BMI: 21.56 (20.42–23.26) Kg/m²). All participants followed the same lower limb strength training program (2 exercises; 4 sets of 10 repetitions at 75% 1RM with progressive loading). Additionally, HG underwent two weekly sessions of exposure to extreme heat in a sauna (100 ± 2 °C and 24 ± 1% relative humidity, four sets of 10 min, 2 days per week). The intervention lasted for 4 weeks, followed by a 4-week deconditioning period. Maximum isometric knee flexion-extension strength, maximum counter-resistance strength, as well as body composition and anthropometric variables were assessed. Results: The HG group significantly increased body weight (p < 0.05) and muscle mass (p < 0.05), while their sum of six skinfolds (Σ6 skinfolds) significantly decreased (p < 0.05). Both groups improved their 1RM squat performance following the intervention program (p < 0.05; HG: r = 0.86; NG: r = 0.89). However, only the HG group continued to improve their squat 1RM after the deconditioning period (p < 0.001; r = 0.93), as well as their leg press 1RM (p < 0.01; r = 0.94). Maximal isometric strength increased only in the NG group at the end of the training program, with a significant increase in knee flexion torque (p < 0.05; r = 0.76). In contrast, the HG group showed significant increases in isometric strength after the deconditioning period in both knee extension (p < 0.05; r = 0.76) and knee flexion (p < 0.05; r = 0.75). Conclusions: A four-week period of passive sauna bathing at extreme heat appears to alter the chronology of strength responses. It also seems to induce favorable responses in terms of strength development and body composition. Full article

Background/Objectives: Total hip arthroplasty (THA) is a widely accepted and effective intervention for advanced degenerative hip disease. However, prosthetic dislocation remains one of the most common postoperative complications. This study aimed to evaluate the biomechanical consequences of implant positioning variations and their influence on prosthetic stability. Methods: A three-dimensional finite element model (FEM) of the pelvis and hip joint was developed using SolidWorks Professional 2025, based on CT imaging of an anatomically normal adult. Multiple implant configurations were simulated, varying acetabular cup inclination and anteversion angles, femoral stem depth, and femoral offset. Muscle force vectors replicating single-leg stance conditions were applied according to biomechanical reference data. The mechanical performance of each configuration was quantified using the safety factor (SF), defined as the ratio of allowable material stress to calculated stress in the model. Results: The configuration with 45° cup inclination, 15° anteversion, standard femoral offset, and optimal stem depth demonstrated the highest SF values (9–12), indicating a low risk of mechanical failure or dislocation. In contrast, malpositioned implants—particularly those with low or high anteversion, excessive offset, or shallow stem insertion—resulted in a marked decrease in SF values (2–5), especially in the anterosuperior and posterosuperior quadrants of the acetabular interface. Conclusions: The findings underscore the critical importance of precise implant alignment in THA. Even moderate deviations from optimal positioning can substantially compromise biomechanical stability and increase the risk of dislocation. These results support the need for individualized preoperative planning and the use of assistive technologies during surgery to enhance implant placement accuracy and improve clinical outcomes. Full article

Background/Objectives: There are very few publications on unplanned excisions of great saphenous vein leiomyosarcomas (GSV-LMS), and their impact on the prognosis of the disease is not well known. The objective of this study is to present a series of nine new leiomyosarcomas of the great saphena vein (LMS-GSV) cases, with the aim of increasing diagnostic awareness and proposing guidelines for therapeutic management. Methods: This is a prospective single-centre study of a series of nine GSV-LMS in thigh (stage IIIA AJCC), knee and proximal leg (IB, 1 II and 3 IIIA), and ankle (2 IIIB and 1 II). Eight patients were female, and the mean age was 72 years. All patients were surgically treated. Five (56%) were unplanned excisions. All these patients were reoperated on to attempt wide resection margins. In a patient, an infra-patellar amputation was performed. Another amputation was refused by another patient. Eight patients received adjuvant radiotherapy. Results: One patient died 8 years after amputation for a reason other than LMS. The patient who refused amputation has been alive, disease-free, for 28 months. The mean follow-up of surviving patients was 39 months (6–78 months). In these patients, there were no local recurrences or metastases. The mean functional outcome according to the MSTS score was 28.9 (range: 24–30). Conclusions: Unplanned excision of GSV-LMS can be prevented through clinical and imaging suspicion. Surgery and re-excision in case of inadequate previous margins and adjuvant radiotherapy lead to a good oncological and functional outcome. Full article

Background: Previous research has identified center of mass vertical oscillation and leg stiffness as the most common variables differentiating Natural and Groucho running techniques. The aim was to assess the inter-session reliability and inter-technique sensitivity of synchronized inertial measurement units and contact grids in quantifying kinematic and kinetic differences between Natural and Groucho running techniques. Methods: Eleven physically active and healthy males ran at a speed 50% higher than transition speed. Two sessions for Natural and two for Groucho running were performed, each lasting 1 min. Results: Most variables exhibited a similar inter-session reliability across running techniques, except contact time and center of mass vertical displacement, ranging from moderate to good (ICC = 0.538–0.897). A statistically significant difference between running techniques was found for all variables (p < 0.05), except for contact time and center of mass vertical oscillation (p > 0.05), likely due to inconsistency in reliability depending on the running technique, which may have covered the underlying differences. Conclusions: We can conclude that the combination of synchronized inertial measurement units and contact grids showed potentially acceptable reliability and sufficient sensitivity to recognize and differentiate between Natural and Groucho running techniques. The results may contribute to a broader understanding of the differences between these two running techniques and encourage the increased use of these devices within therapeutic, recreational, and sports running contexts. Full article

To address the ill-posedness of the Hessian matrix in monocular visual-inertial SLAM (Simultaneous Localization and Mapping) caused by unobservable depth of feature points, which leads to convergence difficulties and reduced robustness, this paper proposes a Pre-Dog-Leg feature optimization method based on an adaptive preconditioner. First, we propose a multi-candidate initialization method with robust characteristics. This method effectively circumvents erroneous depth initialization by introducing multiple depth assumptions and geometric consistency constraints. Second, we address the pathology of the Hessian matrix of the feature points by constructing a hybrid SPAI-Jacobi adaptive preconditioner. This preconditioner is capable of identifying matrix pathology and dynamically enabling preconditioning as a strategy. Finally, we construct a hybrid adaptive preconditioner for the traditional Dog-Leg numerical optimization method. To address the issue of degraded convergence performance when solving pathological problems, we map the pathological optimization problem from the original parameter space to a well-conditioned preconditioned space. The optimization equivalence is maintained by variable recovery. The experiments on the EuRoC dataset show that the method reduces the number of Hessian matrix conditionals by a factor of 7.9, effectively suppresses outliers, and significantly improves the overall convergence time. From the analysis of trajectory error, the absolute trajectory error is reduced by up to 16.48% relative to RVIO2 on the MH_01 sequence, 20.83% relative to VINS-mono on the MH_02 sequence, and up to 14.73% relative to VINS-mono and 34.0% relative to OpenVINS on the highly dynamic MH_05 sequence, indicating that the algorithm achieves higher localization accuracy and stronger system robustness. Full article

This study aimed to test the reliability of seven functional performance tests in amateur trail runners, including ankle mobility, balance, hopping, and countermovement jump (CMJ) tests. The sample consisted of 35 runners who were evaluated in two sessions separated by 7 to 14 days, which varied due to participants’ scheduling constraints. Relative reliability was assessed using the Intraclass Correlation Coefficient (ICC, which indicates consistency between repeated measures), the Standard Error of Measurement (SEM, which reflects measurement precision), and the Minimal Detectable Change (MDC, which represents the smallest real change beyond measurement error). The results show high reliability in almost all tests. The Lunge Test obtained an ICC of 0.990 and 0.983 for distance, and 0.941 and 0.958 for angular measurements in both legs. The Hop Tests showed moderate reliability with ICC above 0.7 In contrast, the Y Balance Test demonstrated lower reliability, with ICC values ranging from 0.554 to 0.732. The CMJ test showed good reliability, with an ICC ranging from 0.753 to 0.894, an SEM between 5.79% and 11.3%, and an MDC ranging from 15.54% to 31.44%, making it useful for assessing lower limb explosive strength. Both tests presented comparatively higher error values, which should be considered when interpreting individual changes. These findings support the use of these tests as valid and reliable tools for evaluating ankle dorsiflexion, balance, functional symmetry, and lower limb explosive strength in amateur trail runners, prior to training programs or injury prevention strategies, provided that standardized protocols and validated measuring instruments are used. Full article

This article aims to investigate the impact of sustainable assets on dynamic portfolio optimization under varying levels of investor risk aversion, particularly during turbulent market conditions. The analysis compares the performance of two portfolio types: (i) portfolios composed of non-sustainable assets such as fossil energy commodities and conventional equity indices, and (ii) mixed portfolios that combine non-sustainable and sustainable assets, including renewable energy, green bonds, and precious metals using advanced Deep Reinforcement Learning models (including TD3 and DDPG) based on risk and transaction cost- sensitive in portfolio optimization against the traditional Mean-Variance model. Results show that incorporating clean and sustainable assets significantly enhances portfolio returns and reduces volatility across all risk aversion profiles. Moreover, the Deep Reinforcing Learning optimization models outperform classical MV optimization, and the RTC-LSTM-TD3 optimization strategy outperforms all others. The RTC-LSTM-TD3 optimization achieves an annual return of 24.18% and a Sharpe ratio of 2.91 in mixed portfolios (sustainable and non-sustainable assets) under low risk aversion (λ = 0.005), compared to a return of only 8.73% and a Sharpe ratio of 0.67 in portfolios excluding sustainable assets. To the best of the authors’ knowledge, this is the first study that employs the DRL framework integrating risk sensitivity and transaction costs to evaluate the diversification benefits of sustainable assets. Findings offer important implications for portfolio managers to leverage the benefits of sustainable diversification, and for policymakers to encourage the integration of sustainable assets, while addressing fiduciary responsibilities. Full article

Background/Objectives: The sequelae from conditions affecting the proximal femur may cause instability, pain, leg length discrepancies and abnormal gait. Treatment options include arthrodesis and total hip arthroplasty, but both alternatives have limitations in young patients with severe deformities. Pelvic support osteotomy constitutes a viable option in these cases. The present study analyses the effectiveness and safety of the procedure. Methods: This was a retrospective observational study on patients with an unstable or stiff hip treated with a pelvic support osteotomy. Both the results obtained and the complications that occurred were subjected to a statistical analysis. In addition, a narrative literature review was carried out to elucidate the biomechanical rationale and the results of the technique. Results: This study included a total of 12 patients (8 male and 4 female) with a mean age of 13 years (range: 0–19). All cases were unilateral and the mean follow-up time was 6.9 years (range: 1–10). Preoperative leg length discrepancy was 8 cm (range: 5–10), and all patients presented with a marked Trendelenburg sign. The mean leg lengthening achieved was 8 cm (range: 8–10), following a mean external fixation time of 263 days (range: 180–360), which entails an external fixation index of 32.5 days per centimeter lengthened (range: 25–37). Mean leg length discrepancy fell to 0.9 cm (range: 0–3) and the Trendelenburg sign improved following treatment: it disappeared in three patients (25%), it became mild in seven (58%), and it improved to moderate in two (17%). Eight patients (66%) experienced some sort of complication over the course of treatment. Conclusions: Pelvic support osteotomies, combined with femoral lengthening, are a safe and effective option for managing severely damaged hips in children and adolescents. Full article

Objective: This study aimed to experimentally investigate the biomechanical and performance differences between the grab start (GS) and the kick start (KS) with each leg on the kickplate (KSR, KSL) in Bi-Finswimming (BFS). It focused on the effect of foot placement on the starting block, equipped with an adjustable, inclined rear kickplate (Omega, OSB11), to determine potential performance advantages and contribute evidence-based recommendations for optimizing start techniques in competitive BFS. Methods: Thirteen national-level finswimmers (seven males, six females; age: 17.7 ± 2.1 years) voluntarily participated. Each athlete performed two trials of three start techniques (GS, KSR, KSL) over three days in a randomized order. Four synchronized cameras recorded video data. Performance metrics (time to 5 m (T5), 15 m (T15), 25 m (T25), reaction time, block time (BT), flight time (FT), and entry characteristics) along with joint angles (hip, knee, ankle), were analyzed using Kinovea software (v. 2024.1). A two-way repeated measures ANOVA (start type × gender) was conducted to analyze performance metrics, and a paired-sample t-test assessed differences in joint angles. Also, correlations between dependent (type of start) and independent variables (start-examined variables) were examined through bivariate Pearson’s r analysis. Results: No significant gender differences were found (p > 0.05). Significant differences emerged between the starting techniques, with KS showing faster T5, T15, and T25 (p < 0.001, η²_p = 0.6; p < 0.001, η²_p = 0.5; p < 0.05, η²_p = 0.3, respectively). BT was significantly longer in GS compared to KS (p < 0.001, η²_p = 0.8), while FT was shorter in GS (p = 0.002, η²_p = 0.4). Faster T5, T15, and T25 were associated with increased flight distance and longer FT in KSL. Conclusions: The kick start generally outperforms the grab start, especially in block time, in Bi-Finswimming. These preliminary results suggest that it could be considered for future discussion regarding potential legalization by the World Underwater Federation, pending further research. Full article