Search Results (210)

This study, inspired by the impact resistance of the pistol shrimp’s predatory claw, investigates the design and optimization of bionic energy absorption structures. Four types of bionic hierarchical porous metamaterial lattice structures with a negative Poisson’s ratio were developed based on the microstructure of the pistol shrimp’s fixed claw. These structures were validated through finite element models and quasi-static compression tests. Results showed that each structure exhibited distinct advantages and shortcomings in specific evaluation indices. To address these limitations, four new bionic structures were designed by coupling the characteristics of the original structures. The coupled structures demonstrated a superior balance across various performance indicators, with the EOS (Eight pillars Orthogonal with Side connectors on square frame) structure showing the most promising results. To further enhance the EOS structure, a parametric study was conducted on the distance d from the edge line to the curve vertex and the length-to-width ratio y of the negative Poisson’s ratio structure beam. A fifth-order polynomial surrogate model was constructed to predict the Specific Energy Absorption (SEA), Crush Force Efficiency (CFE), and Undulation of Load-Carrying fluctuation (ULC) of the EOS structure. A multi-objective genetic algorithm was employed to optimize these three key performance indicators, achieving improvements of 1.98% in SEA, 2.42% in CFE, and 2.05% in ULC. This study provides a theoretical basis for the development of high-performance biomimetic energy absorption structures and demonstrates the effectiveness of coupling design with optimization algorithms to enhance structural performance. Full article

Objective: Head-to-head evidence comparing closed-kinetic-chain (CKC) and open-kinetic-chain (OKC) training on balance in middle-aged women with knee osteoarthritis (KOA) is limited. Purpose: To compare 10-week hip abduction/external rotation-focused CKC versus OKC on static and dynamic balance. Methods: Twenty-two women with KOA were randomized to CKC (n = 11) or OKC (n = 11) and trained twice weekly for 10 weeks. The primary outcome was the center of pressure (COP) during single-leg stance (AP/ML range, excursion, velocity, and RMS); the secondary outcome was the Y-Balance Test (YBT) composite score. Results: CKC produced significant within-group reductions across all COP variables and significant YBT increases for both affected and unaffected limbs (p < 0.05). OKC showed only small changes in select COP indices and no meaningful change in YBT. Post-intervention between-group comparisons consistently favored CKC for AP/ML and total COP excursion/velocity and for the YBT composite score (p < 0.05). Conclusions: Under weight-bearing conditions, a hip-focused CKC program that promotes multi-joint coordination and co-contraction yields broader and more consistent improvements in postural stability and dynamic balance than OKC in middle-aged women with KOA. These findings support prioritizing CKC when rehabilitation aims include gait and functional stability. Full article

Background and Objectives: Chronic ankle instability (CAI), a prevalent injury among female volleyball players, can negatively affect functional performance and increase the risk of further injury. The aim of this study was to compare functional movement quality, dynamic balance, vertical jumping performance, hip muscle strength, and risk of injury between adolescent female volleyball players with unilateral CAI and those without CAI. Materials and Methods: This cross-sectional study included 46 adolescent female volleyball players, divided into CAI (n = 23) and control (n = 23) groups based on predefined criteria. Functional movement quality was assessed using the Functional Movement Screen (FMS), and dynamic balance was evaluated with the Y-Balance Test (YBT). Maximal isometric strength of the hip muscles (flexors, extensors, abductors, adductors, and internal and external rotators) was measured using hand-held dynamometry, and vertical jumping performance was assessed using countermovement jump tests. Injury risk was classified based on established cut-off values for the FMS-composite and YBT-anterior reach asymmetry scores. Results: The CAI group demonstrated significantly lower FMS-composite scores (p = 0.007), reduced anterior reach on the YBT (p = 0.004), and decreased strength in the hip flexors (p = 0.007) and hip adductors (p = 0.044), supported by moderate effect sizes. No significant group differences were observed in the other YBT directions, vertical jump tests, or the other hip muscles (p > 0.05). A greater proportion of athletes in the CAI group were classified as high risk for injury based on both FMS-composite (p = 0.022) and YBT-anterior reach asymmetry (p = 0.001) cut-off values, supported by moderate and relatively strong effect sizes, respectively. Conclusions: Adolescent female volleyball players with unilateral CAI showed impaired movement quality, balance deficits, hip muscle weakness, and increased injury risk. These results highlight the importance of targeted interventions and broader investigations into CAI in adolescent athletes. Full article

To address the inefficiencies of traditional numerical simulations and the high cost of experimental validation in the aerodynamic–stealth integrated design of S-shaped inlets for aero-engines, this study proposes a novel parameter prediction model based on a fuzzy C-means (FCM) clustering and nonlinear dynamic adaptive particle swarm optimization-enhanced radial basis function neural network (NDAPSO-RBFNN). The FCM algorithm is applied to reduce the feature dimensionality of aerodynamic parameters and determine the optimal hidden layer structure of the RBF network using clustering validity indices. Meanwhile, the NDAPSO algorithm introduces a three-stage adaptive inertia weight mechanism to balance global exploration and local exploitation effectively. Simulation results demonstrate that the proposed model significantly improves training efficiency and generalization capability. Specifically, the model achieves a root mean square error (RMSE) of $3.81\times {10}^{-8}$ on the training set and $8.26\times {10}^{-8}$ on the test set, demonstrating robust predictive accuracy. Furthermore, $98.3\%$ of the predicted values fall within the $y=x\pm 3\beta$ confidence interval ($\beta =1.2\times {10}^{-7}$). Compared with traditional PSO-RBF models, the number of iterations of NDAPSO-RBF network is lower, the single prediction time of NDAPSO-RBF network is shorter, and the number of calls to the standard deviation of the NDAPSO-RBF network is lower. These results indicate that the proposed model not only provides a reliable and efficient surrogate modeling method for complex inlet flow fields but also offers a promising approach for real-time multi-objective aerodynamic–stealth optimization in aerospace applications. Full article

Aim of the Study: To determine whether adding a lateral extra-articular tenodesis (LET) to primary anterior cruciate ligament reconstruction (ACLR) lowers graft-failure risk and improves functional recovery in competitive athletes with high-grade pivot-shift. Methods: Multicentre retrospective cohort with 1:1 propensity-score matching (age, sex, sport, graft, centre). Competitive athletes with pivot-shift grade ≥ 2 who underwent primary ACLR with hamstring or bone–patellar tendon–bone (BPTB) autografts (2018–2024) were eligible. The primary outcome was graft failure within 24 months (composite of revision ACLR, symptomatic rotatory laxity with pivot-shift ≥ 2 plus KT-1000 > 5 mm, or MRI-confirmed rupture). Time-to-event was summarised with Kaplan–Meier (KM) curves and log-rank tests. Secondary outcomes included residual rotatory laxity and functional performance (single-leg hop, side hop, Y-Balance) analysed as the proportion achieving Limb Symmetry Index ≥ 90% at 6 and 24 months and as continuous LSI means. Two-sided α = 0.05; secondary outcomes were prespecified without multiplicity adjustment. Results: Of 1368 ACL reconstructions screened, 97 eligible athletes were identified; 92 were analysed after matching (46 isolated ACLR; 46 ACLR + LET; mean follow-up 30.0 ± 4.2 months). KM survival at 24 months was 95.7% after ACLR + LET versus 82.6% after isolated ACLR (log-rank p = 0.046). The absolute risk reduction was 13.0% (Number Needed to Treat 8; 95% CI 4→∞). In graft-type subgroups, failures were 6/32 vs. 1/30 for hamstring and 2/14 vs. 1/16 for BPTB (ACLR vs. ACLR + LET, respectively); there was no evidence of interaction (Breslow–Day p = 0.56). At 6 months, a higher proportion of ACLR + LET athletes achieved LSI ≥ 90% across tests—single-leg hop 77.8% vs. 40.9% (p = 0.0005), side hop 62.2% vs. 34.9% (p = 0.012), Y-Balance 84.4% vs. 59.1% (p = 0.010), with a larger mean LSI (between-group differences +8.2 to +9.1, all p < 0.001). By 24 months, threshold attainment largely converged (all p ≥ 0.06), while mean LSI differences persisted but were smaller (+3.9 to +4.9, all p ≤ 0.001). Conclusion: In competitive athletes with high-grade pivot-shift undergoing accelerated, criteria-based rehabilitation, adding LET to primary ACLR was associated with lower graft-failure risk and earlier functional symmetry, with consistent effects across hamstring and BPTB autografts. Given the observational design, causal inference is limited; confirmation in randomized and longer-term studies is warranted. Full article

Background/Objectives: Maintaining proper posture and preventing musculoskeletal pain are essential for the healthy development of young football players. Contemporary concepts of postural control emphasize the importance of the lumbopelvic-hip complex and the activation of deep trunk muscles. This study aimed to evaluate the effects of a structured core stabilization training program on postural parameters and pain reduction in young football players. Methods: A total of 182 male football players, aged 9–15 years, were enrolled and allocated to either the intervention or control group. The 12-week intervention consisted of exercises targeting both local and global trunk stabilizers. Assessments included measurements of spinal curvatures, trunk rotation angles, lower limb loading symmetry, and postural stability using the TMX-127 digital inclinometer (Saunders Group Inc., Chaska, MN, USA) and the Baseline scoliometer (Fabrication Enterprises, Inc. New York, USA). Pain intensity was measured using the Visual Analogue Scale (VAS). Repeated-measures statistical analyses were performed with a significance level set at p ≤ 0.05. Results: The intervention group showed significant improvements in trunk rotational parameters, with reductions in ATR values at C7/Th1 (−0.54°) and L5/S1 (−0.49°). SATR values decreased by −0.28° between the second and third assessments. Symmetry of lower limb loading under eyes-open conditions improved significantly (p < 0.00195). No significant changes were observed in dynamic balance, as assessed by the Y-Balance Test (p > 0.05). Pain intensity decreased from 3.33 to 2.55 on the VAS, reflecting a reduction of 0.78 points. Conclusions: Systematic core stabilization training enhances postural quality and reduces the occurrence and severity of musculoskeletal pain in young football players, with lasting effects—except for postural control under conditions of reduced visual input. This type of training represents an effective physioprophylactic strategy, supporting postural control and lowering the risk of injuries. To maintain these benefits, continued training that incorporates balance and proprioceptive exercises is recommended. Full article

Objectives: The primary objective was to investigate and compare the effects of three paired-pulse repetitive trans-spinal magnetic stimulation (PP-rTSMS) protocols on balance control and corticospinal network function. Methods: PP-rTSMS (800 pulses, frequency 100 Hz, intensity 70% of the resting motor threshold) was applied over the eighth thoracic vertebra (Th8) in twenty-seven young healthy individuals. Each proband received three verum sessions (using a verum coil with handle oriented (i) cranially, (ii) caudally, and (iii) laterally) and (iv) one sham session (using a sham coil) in a randomised order. Balance ability (Y Balance Test) and corticospinal network functions (motor evoked potentials (MEPs), cortical silent periods (SCPs)) were tested immediately (i) prior to and (ii) after each interventional session. Results: Each verum session induced a significant improvement in balance ability (cranially (F_1,26 = 8.009; p = 0.009; η² = 0.236), caudally (F_1,26 = 4.846; p = 0.037; η² = 0.157), and laterally (F_1,26 = 23,804; p ≤ 0.001; η² = 0.478) oriented grip) as compared to the sham session. In addition, the laterally oriented coil grip was associated with significantly greater balance benefits than both the cranial (F_1,26 = 10.173; p = 0.004; η² = 0.281) and caudal (F_1,26 = 14.058; p ≤ 0.001; η² = 0.351) grip orientations. No significant intervention-induced effects were detected on corticospinal network functions. Conclusions: Our data show that PP-rTSMS effectively supports balance control and that coil orientation significantly influences these effects. Further studies should test variations of this promising approach on healthy and disabled cohorts. Full article

Background/Objectives: Diabetic retinopathy is a leading cause of vision impairment worldwide, and the development of reliable automated classification systems is crucial for early diagnosis and clinical decision-making. This study presents a comprehensive comparative evaluation of two state-of-the-art deep learning families for the task of classifying diabetic retinopathy using retinal fundus images. Methods: The models were trained and tested in both binary and multi-class settings. The experimental design involved partitioning the data into training (70%), validation (20%), and testing (10%) sets. Model performance was assessed using standard metrics, including precision, sensitivity, specificity, F1-score, and the area under the receiver operating characteristic curve. Results: In binary classification, the ResNeXt101-64x4d model and RegNetY32GT model demonstrated outstanding performance, each achieving high sensitivity and precision. For multi-class classification, ResNeXt101-32x8d exhibited strong performance in early stages, while RegNetY16GT showed better balance across all stages, particularly in advanced diabetic retinopathy cases. To enhance transparency, SHapley Additive exPlanations were employed to visualize the pixel-level contributions for each model’s predictions. Conclusions: The findings suggest that while ResNeXt models are effective in detecting early signs, RegNet models offer more consistent performance in distinguishing between multiple stages of diabetic retinopathy severity. This dual approach combining quantitative evaluation and model interpretability supports the development of more robust and clinically trustworthy decision support systems for diabetic retinopathy screening. Full article

Background and Objectives: Although the use of allografts in revision anterior cruciate ligament reconstruction is associated with theoretical advantages, it has historically led to poorer clinical results and lower survival rates. However, the heterogeneity of the available literature makes it difficult to elucidate the effectiveness of allographs, as most of the studies published do not make any reference to some of the key aspects related to the processing of the allograft employed. The present study analyzed the clinical results and the survival of allografts in patients undergoing revision anterior cruciate ligament reconstruction with a well-characterized, single type of allograft. Materials and Methods: This was a retrospective observational study analyzing a series of patients undergoing revision anterior cruciate ligament reconstruction with an Achilles tendon allograft with a bone block (FlexiGraft, LifeNet Health), subjected to low-dose irradiation at dry ice temperatures. Preoperative and follow-up clinical variables (IKDC, pain, hop test, and YBT scores) were recorded. Survival was analyzed using the Kaplan–Meier methodology. Results: A total of 39 patients (34 male, 5 female) were included in the study. The mean patient age was 37.3 years and mean postoperative follow-up was 78.7 months. Forty-one percent of patients were competitive athletes, and all of the patients in the sample exhibited preoperative instability. The mean allograft thickness was 9.2 mm. During surgery, 51.3% of patients required meniscus repair and 20.5% had to be treated for chondral defects. At the last follow-up visit, 92.3% of the subjects presented with IKDC grade A and 7.7% with IKDC grade B. The mean subjective IKDC score was 0.79 and mean pain intensity was 1.15 according to the VAS scale. Limb symmetry, as measured by the various hop tests and the Y balance test, were within the safety range, with 74.4% of patients succeeding in returning to their previous level of sport. Ten-year survival was estimated at 97.4%. Conclusions: Allografts obtained and processed following the current regulations governing patient selection and graft harvesting, which are additionally processed without recourse to chemical procedures and sterilized at less than 2 MRad in dry ice conditions, represent an effective and safe alternative in revision anterior cruciate ligament reconstruction. Full article

This study investigated the effects of a single-night sleep extension protocol on physical performance and cognitive function in physically active university students across different times of day. Using a within-subjects, counterbalanced crossover design, 24 physically active university students (17 males, 7 females; age: 22.7 ± 1.6 years) completed performance assessments under normal-sleep and sleep-extension conditions. Participants’ sleep was monitored via wrist actigraphy, and a comprehensive assessment battery comprising vertical jumps, Y-Balance tests, medicine-ball throws, 5 m shuttle-run tests, reaction-time tests, and digit-cancellation tests was administered at baseline (8 PM), morning (8 AM), and afternoon (4 PM). Sleep extension increased total sleep time by approximately 55 min (531.3 ± 56.8 min vs. 476.5 ± 64.2 min; p < 0.001, d = 0.91). Significant improvements were observed in 5 m shuttle-run performance at 8 AM (best distance: 102.8 ± 11.9 m vs. 93.3 ± 8.5 m, p < 0.001, d = 0.93; fatigue index: 13.1 ± 8.3% vs. 21.2 ± 9.5%, p < 0.001, d = 0.90), squat-jump heights (28.2 ± 8.0 cm vs. 26.3 ± 7.2 cm, p = 0.005, d = 0.25), simple reaction time (252.8 ± 55.3 ms vs. 296.4 ± 75.2 ms, p < 0.001, d = 0.66), and digit-cancellation performance (67.6 ± 12.6 vs. 63.0 ± 10.0 targets, p = 0.006, d = 0.40). Sleep extension significantly enhances both physical and cognitive performance in physically active individuals, with effects more pronounced during morning hours, partially attenuating typical circadian performance decline and establishing sleep extension as an effective, non-pharmacological strategy for optimizing performance capabilities. Full article

Objectives: To identify cognitive domains predictive of dynamic balance performance in older adults and inform targeted cognitive-motor interventions aimed at improving balance and reducing fall risk. Methods: This cross-sectional study used hierarchical multiple regression to analyze relationships between cognitive domains and dynamic balance among 62 community-dwelling older adults (≥65 years). Balance was assessed using the Y Balance Test (YBT) and Timed Up and Go Test (TUG), while cognitive function was measured using the Mini-Mental State Examination (global cognition), Stroop Test (inhibition), N-back Test (working memory), and Deary–Liewald Reaction Time Test (processing speed). Statistical analyses were conducted using SPSS, version 28, with significance set at p < 0.05. Results: Although all cognitive domains correlated with dynamic balance, regression analyses indicated that only global cognition and inhibition were significant predictors. Specifically, global cognition significantly predicted both TUG and YBT performance, whereas inhibition uniquely predicted YBT performance (all p < 0.05). Conclusions: Our findings suggest global cognition and inhibition are key cognitive predictors of dynamic balance in older adults. Assessing these domains could identify individuals at risk of impaired balance, facilitating the design of targeted, personalized cognitive-motor interventions. Future research should investigate cognitively enriched exercise programs, including digital therapeutics and wearable technologies, to effectively target these cognitive domains, enhance balance outcomes, and promote sustained physical activity adherence in aging populations. Full article

Injury prevention and performance enhancement are key objectives in sports training. The FIFA 11+ program, originally developed to reduce injury risks, has gained attention for its potential benefits in improving physical performance and dynamic balance. This study aimed to examine the impact of an 8-week FIFA 11+ training program on vertical jump, Illinois Agility, and Y-Balance Test (YBT) performances in adult male handball players. Twenty-five players from two senior national male handball teams were recruited and randomly assigned to an experimental group (n = 13) or a control group (n = 11). Assessments were conducted before and after the intervention, including the countermovement jump (CMJ), the Illinois Agility Test (IAT), and the Y-Balance Test (YBT), which measured anterior (AT), posteromedial (PM), and posterolateral (PL) reach directions as well as a composite score (CS). The FIFA 11+ group showed significant improvements after the eight-week program, with increased CMJ (p = 0.013) and reduced IAT time (p < 0.001). Dynamic balance, as measured by the YBT, improved significantly in both lower limbs (p = 0.022–0.001), with enhanced postural stability across multiple directions (F = 6.92–20.23, p = 0.022–0.001, ηp² = 0.366–0.628, power = 0.68–0.98). In contrast, the control group exhibited minimal or no significant changes. While the results suggest that the FIFA 11+ program can improve specific performance outcomes in this population, the relatively small sample size and focus on a single sport and age group warrant caution in generalizing these findings. Further studies involving larger and more diverse cohorts are recommended. Full article

Background/Objectives: Dominant leg use in badminton may contribute to lower limb asymmetry, potentially affecting performance and injury risk. This study investigated the effects of a 12-week integrated neuromuscular training (NMT) program on sports performance. Methods: Twenty-four well-trained male badminton players (age: 13.5 ± 1.15 years) were randomly assigned to groups based on maturation status (pre-peak height velocity [pre-PHV] and post-peak height velocity [post-PHV]; n = 12 each). All participants completed two NMT sessions weekly. Pre- and post-training assessments included a 20 m sprint, countermovement jump (CMJ), agility t-text, hexagon test, and Y-balance test. Results: Both groups improved significantly across most tests. The post-PHV group (ES: 0.70–1.35) showed greater improvements in sprinting, CMJ, and agility, while the pre-PHV group (ES: 0.39–1.23) improved more in balance and asymmetry. Conclusions: These results underscore the need for age- and maturity-specific training strategies to optimize performance and address asymmetries in youth athletes. Full article

In volleyball, successful offensive performance is influenced not only by physical muscle function but also by injury status. The purpose of this study was to analyze the relationship between muscle function—including strength, balance, and symmetry—and injury history in relation to offensive performance (OP) and ultimately sought to find factors required to improve OP. The final analysis included 60 players in attacking positions (36 in the symmetry group and 24 in the asymmetry group). Muscle strength was assessed using isokinetic testing for shoulder and knee extension. Balance was evaluated using the Upper Quarter Y-Balance Test (UQ-YBT) and the Lower Quarter Y-Balance Test (LQ-YBT). The asymmetry index (AI, ≥10%) was calculated by comparing the dominant and non-dominant sides. The results showed that the asymmetry group had a higher injury rate and lower offensive performance (OP) than the symmetry group (p < 0.05). In multiple regression analysis, no significant predictors were found on the non-dominant side, whereas significant variables were identified only on the dominant side. The key variables influencing OP were shoulder and knee extension strength, UQ-YBT scores, and the AI of knee extension. A 13.8% improvement in shoulder extension strength on the dominant side increased the likelihood of enhanced offensive performance (OP) by 2.54 times. A 10.5% improvement in the asymmetry index (AI) of knee extension was associated with a 1.52-fold increase in OP (p < 0.05). Shoulder and knee flexion did not significantly affect OP in any of the tests (p > 0.05). In conclusion, offensive performance in volleyball is associated with the greater shoulder and knee extension strength of the dominant side, as well as positive changes in UQ-YBT scores and the AI of knee extension. Full article

Early detection of modifiable motor deficits is essential for safe, long-term athletic development, yet most field screens provide only binary risk scores. We therefore designed a practical and interpretable profiling system that classifies youth athletes into one of four functional categories—Functionally Weak, Strength-Deficient, Stability-Deficient, or No Clear Dysfunction—using three common assessments: Functional Movement Screen, hand-held dynamometry, and Y-Balance Test. A total of 46 youth athletes aged 11–16 years participated in the study, including 37 male soccer players (13.3 ± 1.6 y) in the development cohort and 9 handball players (5 male, 4 female; 12.8 ± 0.7 y) in the external validation group. Expert rules based on FMS quartiles and ≤−0.5 SD Z-scores for strength or balance generated the reference labels. The random forest model achieved 81% cross-validated accuracy (with balanced performance across classes) and 89% accuracy on the external handball group, exceeding the performance of the decision tree model. SHAP analysis confirmed that model predictions were driven by domain relevant variables rather than demographics. An accompanying web-based application automatically generates personalized reports, visualizations, and targeted training recommendations, making the system directly usable by coaches and clinicians. Rather than merely predicting injury, this field-ready framework delivers actionable, profile-based guidance to support informed decision making in athlete development. Further validation in larger, sport-diverse cohorts is needed to assess its generalizability and long-term value in practice. Full article