Search Results (349)

Topological indices provide numerical descriptions of graph structure and support graph analysis in cheminformatics, network design, and graph mining. This study presents a reproducible computational framework that combines controlled cyclic-graph generation, structure-preserving transformations, exact computation of six classical topological indices, and multi-output graph neural network regression. The framework evaluates the Wiener, Merrifield–Simmons, Hosoya, first Zagreb, second Zagreb, and Randi’c indices for unicyclic and bicyclic graphs. It represents each graph using sparse connectivity and node-level features that encode degree, cycle membership, pendant connectivity, leaf status, and normalized eccentricity. A graph isomorphism network (GIN) jointly predicts the six indices and is compared with graph convolutional networks (GCNs), graph attention networks (GATs), and descriptor-based regression baselines. The controlled benchmark shows that nonlinear descriptor-based models achieve the lowest aggregate errors because the supplied graph-level descriptors contain strong prior information about graph size, degree structure, branching, and cycle complexity. Although GIN does not achieve the highest overall accuracy, it provides the strongest graph-native performance by learning directly from sparse connectivity and node-level features without requiring a fixed handcrafted graph-level descriptor vector. The proposed surrogate does not replace exact evaluation for isolated small graphs, where exact computation remains more appropriate. Instead, its practical value emerges through repeated evaluations of larger, more complex graph instances. To examine this setting, a computational stress experiment evaluates sparse multicyclic graphs under increasing cyclomatic complexity and measures exact computation time, timeout frequency, prediction accuracy, and the amortized break-even point. The results indicate that surrogate prediction becomes beneficial when combinatorial index computation becomes sufficiently expensive, and the trained model is reused across many structurally related graph queries. An external experiment on circulant graphs also demonstrates that the framework can extend beyond the original graph generators by modifying only the graph-construction stage. Full article

The purpose of this narrative review was to provide a conceptual and applied framework that distinguishes resistance training methods, strategies, and systems and clarifies how these constructs organize established training variables within contemporary recommendations for exercise prescription. The historical, conceptual, and theoretical synthesis was not restricted by publication date and included seminal studies and previous evidence syntheses. In addition, a focused descriptive mapping of primary experimental studies published between January 2021 and April 2026 was conducted using PubMed, Scopus, and Web of Science. This mapping comprised 40 studies assessing acute responses or chronic adaptations to methods including drop sets, rest–pause, pyramidal loading, eccentric training, blood flow restriction, cluster sets, and velocity-based training. Several studies reported no statistically significant between-method differences in selected strength or hypertrophy outcomes; however, their generally small samples and the absence of equivalence or non-inferiority analyses preclude conclusions of true equivalence. Individual studies also reported context-specific differences in session efficiency, fatigue distribution, movement velocity, regional hypertrophy, and contraction-specific adaptations. Given the heterogeneity of the mapped studies and the absence of formal risk-of-bias or certainty-of-evidence assessments, these observations should be interpreted as descriptive and exploratory rather than as evidence of general comparative superiority. Taken together with the broader historical and synthesized literature, the findings suggest that resistance training adaptations are primarily governed by foundational prescription variables, including load, volume, frequency, effort, density, and exercise selection. The principal contribution of this review is therefore to clarify how methods, strategies, and systems can be selected and organized according to specific goals, individual characteristics, and practical constraints. Full article

Smartphone-based augmented reality (AR) may help dentists visualize an implant axis during treatment or training. Before a virtual overlay can be displayed, however, the application must first recognize the real target reliably. This in vitro study tested how five lighting conditions affected recognition of a two-colored, 3D-printed polylactic acid (PLA) dental model by a Unity/Vuforia smartphone application. The application ran on a Samsung Galaxy S22. A GoPro HERO10 recorded the smartphone display at 240 frames per second, and the videos were evaluated frame by frame. Red, green, blue, daylight-like light-emitting diode (LED) and halogen illumination were tested at a central and an eccentric model position, with ten repetitions per condition and position. The model was not recognized under red or blue illumination within the predefined observation interval. Recognition was successful in all repetitions under green, daylight-like and halogen illumination. Recognition speed differed among these successful conditions, and the eccentric position delayed recognition under daylight-like and halogen illumination. A supplementary region-of-interest analysis also showed lighting-dependent differences in image brightness and contrast. These findings indicate that lighting should be standardized and documented when smartphone-based dental AR systems are developed and tested. Full article

This study examined whether barbell velocity can accurately predict relative load during a free-weight parallel squat performed with a deliberate pause between the eccentric and concentric phases in elite Portuguese rugby players. A repeated-measures design was used, in which 25 athletes completed an incremental loading protocol up to their one-repetition maximum (1-RM) on two occasions separated by four weeks. The relationship between mean propulsive velocity (MPV) and %1-RM was analyzed using polynomial regression, and a second-order prediction equation was developed. The model showed a very strong association between MPV and %1-RM (R² = 0.95) with a standard error of estimate of 6.27 %1-RM, indicating good practical accuracy. Test–retest analyses demonstrated high stability of the load–velocity relationship (mean velocity difference: −0.01 ± 0.02 m·s⁻¹). Compared with values reported in other athletic populations, first-division rugby players displayed distinct load–velocity profiles across the full loading spectrum, underscoring the influence of execution technique and population characteristics on load–velocity behavior. These findings support the use of individualized velocity-based prescriptions rather than generalized equations. In conclusion, this study provides a technique- and population-specific prediction equation for the paused parallel back squat, offering a novel and practical tool for regulating training intensity in elite rugby players. Full article

We present a computational proof of concept, inspired by a recent patent developed by Nikolai Suchkov and Siegfried Wahl (European Patent Office EP4179957A1), of a virtual multi-eccentric Hartmann–Shack (HS) aberrometer for simultaneous measurement of peripheral ocular aberrations. The simulated system records nine wavefronts distributed within a region of approximately 20° around the fovea and is evaluated under ideal and realistic conditions, including speckle and illumination inhomogeneities in HS sensor images. Aberrations are quantified by two approaches: a traditional centroid-based method and a custom-made ResNet convolutional neural network (CNN) trained on simulated HS images. Results show that speckle markedly degrades traditional reconstructions for eccentric points, whereas the CNN (trained with speckled data) exhibits greater robustness and accuracy across all nine wavefronts. This model serves as a proof of concept toward a physical multi-eccentric aberrometer that acquires nine wavefronts in a single shot, thereby eliminating sequential point-by-point acquisition, reducing measurement time, and limiting motion-induced variability between measurements. The approach has potential applications in evaluating ocular treatments and in longitudinal studies of ametropias where peripheral aberrations are implicated. Full article

Background and Objectives: The back squat is widely used in resistance training, performance enhancement, and rehabilitation, and barbell position and squat depth are key modifiable variables that may influence neuromuscular demand. This study investigated the effects of barbell position and squat depth on trunk and lower-extremity muscle activation during the back squat. Materials and Methods: Twenty-two adult men with at least 2 years of back-squat experience performed high-bar and low-bar back squats to knee-flexion angles of 50°, 90°, and 130° using a standardized external load corresponding to 80% of each participant’s habitual one-repetition maximum (1RM). Conditions were presented in randomized order. Surface electromyography was used to record the rectus femoris, vastus medialis, vastus lateralis, gluteus maximus, semitendinosus, biceps femoris, rectus abdominis, and erector spinae. Electromyographic activity was analyzed separately for eccentric and concentric phases and normalized to maximal voluntary isometric contraction (%MVIC). Results: Increasing squat depth most consistently increased quadriceps and erector spinae activation, indicating greater knee extensor and trunk extensor demand at deeper positions. Rectus abdominis activation showed a depth-related effect during the concentric phase, with only isolated pairwise differences during the eccentric phase, whereas gluteus maximus activation showed limited modulation. Barbell position produced selective phase- and depth-dependent responses: the low-bar squat showed greater hamstring and erector spinae activation in specific comparisons, whereas the high-bar squat showed greater knee-extensor activation at selected depths, most clearly in the rectus femoris. Conclusions: Barbell position and squat depth modify relative neuromuscular demand during the back squat and may be used to adjust the emphasis on knee extensor, trunk stabilizer, and posterior-chain demands rather than to target a single muscle group in isolation. Full article

This study compared the effects of variable-resistance compound training versus constant-resistance compound training on lower-limb explosive power in judo athletes, aiming to identify an effective and safe training method. Methods: Sixteen judo athletes were randomized into VRT (n = 8) or RT (n = 8) groups for a 6-week, twice-weekly intervention. Outcomes included rate of force development (RFD), counter movement jump (CMJ), squat jump (SJ), eccentric utilization ratio (EUR), reactive strength index (RSI), squat 1RM, muscle architecture, and Special Judo Fitness Test (SJFT). After 6 weeks of training intervention, the time × group interaction effects were significant between the variable-resistance compound training group and the constant-resistance compound training group in the following parameters: CMJ (p < 0.01, η² = 0.605), SJ (p < 0.01, η² = 0.391), EUR (p < 0.01, η² = 0.308), RSI (p < 0.01, η² = 0.306), RFD (p < 0.01, η² = 0.401), squat 1RM (p < 0.01, η² = 0.328), SJFT index (p < 0.01, η² = 0.537), femoral rectus feather angle (p < 0.05, η² = 0.380), femoral rectus thickness (p < 0.05, η² = 0.288), femoral rectus cross-sectional area (p < 0.01, η² = 0.868), gastrocnemius feather angle (p < 0.05, η² = 0.274), and gastrocnemius thickness (p < 0.05, η² = 0.390). No significant group effects were observed for any of the parameters (p > 0.05). Conclusion: Both variable-resistance training (VRT) and constant-resistance training (CRT) are effective in enhancing lower-body power in judo athletes; both training methods can be regarded as effective options for developing lower-body power in judo athletes, although VRT may offer a slight advantage in specific performance domains. Full article

Ocular ductions deform the optic disc and peripapillary blood vessels, and deformations can be interpreted as mechanical strain. We used confocal scanning laser ophthalmoscopy (cSLO) to map strain in disc and peripapillary retinal vessels associated with the cardiac pulse and determine if such strain is influenced by gaze direction. Sets of 13 infrared cSLO images were obtained sequentially for each eye using a Heidelberg Spectralis scanner in cinematic mode over a 3 sec interval in adults. Imaging was repeated in central, and horizontally (30° adduction/abduction) and vertically eccentric gazes (10° supraduction/infraduction). Retinal vessels, optic disc, and fovea were segmented using custom-trained, deep learning-based models. Frame to frame vascular displacements were automatically determined using optical flow analysis, allowing computation of equivalent strain. A total of 25 eyes of 13 subjects of mean age 39 ± 18 (standard deviation, range: 25 to 81) years were included. Average equivalent strain over 3 sec ranging from 0.27% to 0.36% exceeded the 0.16% noise threshold across all gazes and regions, indicating measurable pulse-induced deformation. After adjustment for age and axial length, pulsatile maximum and minimum strain were influenced slightly by gaze direction, maximally for supraduction, whereas mean strain did not vary significantly with gaze. The cardiac pulse induces measurable deformation of retinal vessels that can be quantified as equivalent strain in the image plane using optical flow-derived displacement fields. However, the interaction of pulse strain with gaze direction is unlikely to be a significant confound for investigations of strains associated with eye movements. Full article

Background and Objectives: Persistent quadriceps weakness, muscle atrophy, and functional deficits are common following anterior cruciate ligament (ACL) reconstruction and may compromise return to sport and increase the risk of reinjury. Eccentric-oriented strength training has been widely used to enhance muscle strength and hypertrophy in various musculoskeletal conditions; however, its specific application within ACL rehabilitation remains insufficiently explored. The aim of this scoping review was to map the existing evidence on the use of eccentric-oriented strength training in ACL rehabilitation, identify gaps in the current literature, and provide suggestions for future research. Materials and Methods: A scoping review search was conducted in PubMed, Scopus, Web of Science, and PEDro from inception to February 2026 using the following keywords and Boolean operators: (“anterior cruciate ligament”, “ACL”, “anterior cruciate ligament reconstruction”, “ACLR”) AND (“eccentric training”, “eccentric exercise”, “eccentric loading”, “flywheel training”, “isoinertial training”). Eligible studies included studies that investigated eccentric exercises as part of ACL rehabilitation and reported outcomes related to muscle strength, muscle morphology, functional performance, or return to sport. Data were extracted and synthesized descriptively in accordance with the PRISMA-ScR extension for Scoping Reviews guidelines. Methodological quality and risk of bias were evaluated using the PEDro scale (RCTs) and the ROBINS-I tool (non-randomized studies). Results: Fifteen studies met the inclusion criteria. The included literature primarily examined isokinetic eccentric exercise, eccentric cycling, early progressive eccentric resistance training, Nordic hamstring exercise, eccentric ergometry, and flywheel strength training. Most studies reported improvements in quadriceps strength and muscle morphology, with additional benefits observed in functional performance measures (i.e., hop tests), gait mechanics, and limb symmetry. Evidence was unevenly distributed across rehabilitation phases, with relatively few studies focusing on the mid-phase of ACL rehabilitation. Conclusions: Eccentric-oriented strength training represents a promising but underexplored component of ACL rehabilitation. However, the existing literature lacks standardized protocols, comprehensive outcome measures, and phase-specific guidance, particularly during the mid and late stages of rehabilitation. Further high-quality studies are needed to clarify the optimal timing, dosage, and integration of eccentric training across rehabilitation phases. Full article

Objective: To examine lower-body stretch–shortening cycle (SSC) indicators across chronological age categories and playing positions in elite male youth soccer players. Methods: In a cross-sectional design, 984 male players from Slovakia (U15–U19) completed Squat Jumps (SJ), Countermovement Jumps (CMJ), and Drop Jumps (DJ) using the OptoJump photocell system. Outcomes included Eccentric Utilization Ratio (EUR), Reactive Strength Index (RSI), DJ Ground Contact Time (DJ GCT), and Jump Heights (JH). Differences were tested using factorial ANCOVA (age category × playing position) adjusted for height and weight, followed by Tukey-adjusted post hoc comparisons (p < 0.05). Results: Significant age-category main effects were observed for DJ RSI, DJ JH, CMJ JH, SJ JH, and DJ GCT. The largest effects were for DJ JH, CMJ JH, and SJ JH (ηp² = 0.096–0.112), whereas the DJ GCT effect was statistically significant but small (ηp² = 0.013). EUR showed no significant differences across age categories (p = 0.586). Positional differences were limited overall and mainly evident in selected U19 outcomes, particularly jump-height variables and DJ GCT. Conclusions: Lower-body SSC performance increased across chronological age categories, with the largest separation in jump-height and reactive strength outcomes. These differences likely reflect a combination of maturation, training exposure, and selection rather than chronological age alone. EUR remained stable across age categories and playing positions, although the JH-based ratio has limited sensitivity in the present test configuration. Positional separation emerged mainly at U19, supporting broad SSC development across earlier youth categories and position-sensitive interpretation in the oldest cohort. Full article

The bowling performance of cricket fast bowlers is highly dependent on lower limb power and stiffness. French Contrast Training (FCT) and Velocity-Based Training (VBT) are effective ways to improve rate of force development and peak power. The objective of this study was to investigate the effects of VBT-optimized FCT on the lower limb explosive power and bowling performance of cricket fast bowlers. Twenty adult male medium-fast bowlers volunteered for this study and were evenly divided into an experimental group (EG) and a control group (CG). The EG underwent an 8-week VBT-based FCT program, while the CG completed 8 weeks of traditional resistance training combined with traditional plyometric training. Before and after the intervention, subjects were tested on their Bulgarian split squat load–velocity profile, general lower limb power (countermovement jump height, squat jump height, Eccentric Utilization Ratio, and Reactive Strength Index), and bowling performance metrics (front foot contact time, peak force, impulse, front knee angle at ball release, and ball release speed). The results demonstrated that the EG showing significant advantage over the CG on movement velocity during the Bulgarian split squat at loads 20% 1RM, 40% 1RM, and 60% 1RM (p = 0.008, 0.011, 0.008, ${\eta }_p^2$ = 0.337, 0.313, 0.324). General lower limb power in the EG also improved significantly, with CMJ height, EUR, and RSI showing significant inter-group superiority compared to the CG (p < 0.001, = 0.019, 0.004, ${\eta }_p^2$ = 0.659, 0.281, 0.399). Regarding bowling performance, the EG demonstrated highly significant advantages in front foot contact impulse, front knee angle at ball release, and ball release speed (p < 0.001, ${\eta }_p^2$ = 0.572, 0.590, 0.704). In conclusion, the 8-week VBT-FCT program is more effective than the traditional resistance and plyometric training program of the same duration in enhancing lower limb power and bowling performance for medium-fast cricket bowlers. Full article

Objectives: This study investigated bilateral strength asymmetry, the bilateral asymmetry index, and the bilateral deficit ratio during one-repetition maximum leg press testing performed under bilateral, unilateral, and split-load conditions and examined their associations with isokinetic knee and hip strength asymmetries. Methods: 31 resistance-trained males completed 1RM leg press tests in all loading modes, followed by isokinetic knee flexion/extension and hip extension assessments at 60°·s⁻¹. Results: The repeated measure ANOVA showed that split-load leg press had a significantly greater bilateral deficit ratio (14.29 ± 7.71%) compared to the bilateral condition (5.16 ± 9.60%, p < 0.001). Isokinetic testing showed significant inter-limb differences for knee flexion and extension but not hip extension. The bilateral strength asymmetry varied across tasks (5.17 ± 4.44% in leg press to 17.84 ± 12.40% in eccentric hip extension), while bilateral asymmetry index remained consistently lower. Bilateral strength asymmetry differed significantly across leg press conditions, whereas the bilateral asymmetry index did not. Knee flexion bilateral asymmetry index correlated with dominant and non-dominant hamstring to quadriceps ratios (respectively, r = 0.61; r = 0.37) and cross-limb flexor–extensor ratios (r = 0.42). No significant relationships were found for hip extension asymmetry. Conclusions: Split-load leg press might be used to test lower limb bilateral deficit, because it provides easily detectable deficit values. Unilateral leg press might be used to detect lateral strength differences, since it provides relation to isokinetic strength of knee flexors and extensors. Full article

Background: Sprinting places exceptionally large mechanical demands on the knee flexors, particularly during the late swing phase when the hamstrings are actively lengthened under load. Therefore, coaches and practitioners try to increase the hamstrings’ capacity to absorb energy by various resistance training exercises with high (supramaximal) eccentric intensity. However, it is unclear whether the load parameters are equivalent to maximum sprints. Consequently, the aim of this short study was to compare peak knee power values derived from aggregated previously published datasets of maximum sprints and strenuous hamstring exercises, rather than from a single directly controlled experimental comparison. Methods: Previously published inverse dynamic analyses of sprints, explosive Razor Curls, decelerated Nordic Hamstring Exercise and eccentric isokinetic hamstring tests were aggregated and compared. Results: The combined data showed that both absolute and relative peak knee power were 8 to 14 times higher during sprinting at 10 m/s—primarily due to 6- to 14-fold higher knee extension angular velocities. Conclusions: Peak knee power during maximum sprints was not replicated by the analyzed hamstring exercise conditions, even if they were very explosive and strenuous. Full article

On behalf of the Strength and Conditioning Society (SCS), we are pleased to present the abstracts submitted for the SCS 8th Annual Meeting. The event was held at the Norwegian School of Sport Sciences in Oslo, Norway, on 8–10 October 2025, and comprised several invited sessions held by international and national speakers on a variety of topics related to biochemistry and exercise physiology, strength and conditioning practices and their application to health, injury prevention, and sports performance. These included strength training in high-performance sports, sport science and training–competition load management in elite environments, biochemistry and exercise physiology and prescription, nutrition and biomechanics, among others. The conference also included practical workshops held by renowned academics and practitioners on eccentric training, change of direction ability, and strength and power training in professional team sports, combat sports, and ergospirometry and exercise prescription in specific populations. Finally, the event disseminated up-to-date strength and conditioning research by providing practitioners and researchers with the opportunity to present their most recent findings. All abstracts presented at the SCS 8th Annual Meeting can be found in this Conference Report. Full article

Background: Targeted training interventions, including neuromuscular warm-up protocols, eccentric resistance training, and dynamic stretching exercises, with limited and heterogeneous evidence on recovery strategies, have shown potential benefits for muscle performance and reductions in injury risk. Objective: To synthesize and structure contemporary evidence on exercise-based interventions spanning the pre-activity warm-up through post-activity recovery, emphasizing performance outcomes, injury-related effects, reported dose–response patterns, and implementation characteristics. Methods: This systematic review with structured qualitative synthesis was based on a systematic database search and eligibility screening process (n = 40 studies). Studies evaluating exercise-based interventions targeting injury prevention and/or performance in athletes were included. Data extraction included study design, population characteristics, intervention components, outcomes, and risk-of-bias assessments, which were summarized using comparative tables and descriptive analyses. Due to heterogeneity, results were synthesized qualitatively without meta-analysis. Results: Neuromuscular warm-ups (e.g., FIFA 11+) were frequently linked to reduced reported lower-extremity injury risk, alongside improvements in sprint, jump, and balance performance. Eccentric hamstring training was linked in several studies to lower reported hamstring injury rates and increased eccentric strength and fascicle length, while dynamic warm-ups may acutely improve sprint and jump performance. Evidence regarding recovery modalities was heterogeneous, supporting a cautious and individualized emphasis on sleep, nutrition, and hydration. However, heterogeneity in study designs, outcome measures, and populations limits the comparability and generalizability of the findings. Conclusions: Exercise-based interventions, including neuromuscular warm-ups, eccentric strengthening, dynamic stretching, and progressive load and recovery strategies, may support performance enhancement and injury-risk reduction in youth and adult athletes when appropriately implemented, although interpretation is limited by study heterogeneity. Full article