Search Results (104)

Background: Primitive reflex (PR) assessments based on the Institute for Neuro-Physiological Psychology (INPP) framework are increasingly used in developmental and athletic populations. However, the reproducibility of these observer-based assessments remains insufficiently documented. This study investigated the intra- and inter-rater reliability of subjective PR assessments and examined the potential influence of evaluator expertise in elite youth football athletes. Methods: Sixty-nine male youth football players from an elite academy (age: 18 ± 2 years) participated in this study. PR assessments included the Moro reflex, asymmetrical tonic neck reflex, symmetrical tonic neck reflex, and tonic labyrinthine reflex, evaluated using standardized INPP procedures (0–4 ordinal scoring scale). Intra-rater reliability was assessed by an experienced examiner across three testing sessions performed over six months. Inter-rater reliability was evaluated using standardized video recordings independently scored by two novice raters. Relative reliability was assessed using intraclass correlation coefficients (ICCs) with corresponding 95% confidence intervals (95% CIs), while absolute reliability was quantified using the standard error of measurement (SEM) and the minimal detectable change at the 95% confidence level (MDC95). Results: Good to excellent intra-rater relative reliability (ICC = 0.86–0.98; 95% CI = [0.81–0.99]) was observed, with SEM values of 0.1–0.6 and MDC95 values of 0.3–1.7 points. Moderate to excellent video-based inter-rater reliability was found (ICC = 0.69–0.99; 95% CI [0.56–0.99]), with SEM values of 0.1–0.7 and MDC95 values of 0.3–2.0 points. Pairwise comparisons among raters showed moderate to excellent relative reliability (ICC = 0.57–0.99; 95% CI [0.35–0.99]), with SEM values of 0.1–0.5 and MDC95 values of 0.2–1.3 points. Conclusions: Subjective PR assessments performed using the INPP framework demonstrated good to excellent intra-rater relative reliability and moderate to excellent video-based inter-rater relative reliability, together with generally low absolute measurement error in elite youth football athletes. These findings provide preliminary psychometric support for the use of standardized PR assessments in research and applied sport settings. Full article

Background: Anthropometric analysis has become a key tool for analyzing body composition to assess, monitor, and track structural changes in soccer players. Objective: The objective of this study was to analyze the scientific literature on body composition and anthropometry in soccer using a bibliometric analysis. Material and Methods: The following databases were consulted: Scopus, Web of Science (WoS), PubMed (Medline), SportDiscus, and the ScienceDirect publishing platform. The study included documents published between 1990 and 2025. Data was selected following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines statement flowchart and subsequently analyzed using Bibliometrix and R software to identify keywords, frequency of occurrence, journal analysis, countries, and other bibliometric indicators. Results: A total of 384 documents met the inclusion criteria. Spain, Italy, Brazil and Portugal stand out as the countries with the highest output. These countries are associated with the most representative authors, led by Suarez-Arrones, L; Nikolaidis, PT; and Campa, F., who are in turn associated with the most representative concepts: “Male”, “Adolescent” and “Athletic performance”. The most prevalent concepts are population-based: “Adolescent” and “Young adult”. The top three organizations in terms of contributing to the scientific study of body composition and anthropometry were the University of the Basque Country, Pablo de Olavide University, and the University of Coimbra. It can be observed that most of the literature has focused on youth (29.16% of the total documents), followed by elite players (22.91%) and professionals (14.84%), where the focus is on those aged 14 to 19 years and playing at highly competitive levels, seeking peak performance. Conclusions: Methodological heterogeneity in evaluation protocols constitutes the main structural shortcoming in this field: 32.29% of studies do not specify their protocols, which compromises the comparability of the results. The widespread adoption of international standards, such as the International Society for the Advancement of Kinanthropometry (ISAK) methodology, along with a requirement to indicate the instrument used and the evaluator’s certification level, is a priority for improving the quality of scientific communication in future research. Full article

Background: Team sports often involve high-intensity unilateral actions that can lead to neuromuscular asymmetries, increasing injury risk and reducing performance, particularly in young female athletes. Methods: This study quantified and compared inter-limb asymmetries in single-leg countermovement jumps (slCMJ) across sexes and sports in 96 youth elite athletes (16.42 ± 1.03 years; 1.83 ± 0.09 m; 74.36 ± 8.69 kg) from basketball, handball, and volleyball. Using a force plate, asymmetries were assessed, and statistical analyses (t-test, ANOVA) identified differences. Results: Females showed greater asymmetry in jump height (9.64 ± 6.43% vs. 6.48 ± 4.87%, p = 0.01, d = 0.59), whereas males exhibited higher asymmetry in time to take-off (10.32 ± 7.5% vs. 6.4 ± 4.7%, p = 0.003, d = 0.63). Volleyball players displayed the lowest asymmetry in jump height (7.05 ± 4.9%) compared to basketball (8.73 ± 7.2%) and handball (11.88 ± 9.7%, p = 0.05), and in relative maximum power (4.63 ± 3.7%) compared to basketball (7.75 ± 5.3%, p = 0.04) and handball (6.51 ± 4.7%). Conclusions: These findings highlight sex- and sport-specific neuromuscular asymmetry patterns, emphasizing their relevance for injury prevention and performance strategies. However, asymmetries are highly variable, influenced by multiple factors. Full article

The aim of this study was to analyze the effects of different small-sided game (SSG) formats on internal load, perceived enjoyment, and technical-tactical performance in elite youth water polo players. Twenty male athletes (U16, n = 10; U18, n = 10) performed in three 4 vs. 4 SSG formats with different time of ball possessions and size of field areas. Technical-tactical variables were assessed using the Team Sport Assessment Procedure (TSAP), while internal load and enjoyment were measured through session-RPE (s-RPE) and a 7-point enjoyment Likert scale (ENJ). Data were analyzed using linear mixed-effects models and Spearman correlations. SSG format significantly influenced internal load, with higher RPE values (F = 6.878; p = 0.004) and s-RPE (F = 6.27; p = 0.006) observed in larger formats of the SSG. Technical-tactical indices were also affected, with significant differences found for volume of play (VP) (F = 17.041; p < 0.001) and performance score (PS) (F = 18.574; p < 0.001), showing higher values in the smallest format (SSG1). Enjoyment differed between categories (F = 13.136; p = 0.003), with higher scores in U16 players. No significant correlations were found between final RPE and TSAP indices (p > 0.05). These findings suggest that SSGs are effective tools for simultaneously developing physical and technical-tactical skills. Coaches should manipulate task constraints to balance training intensity and skill development, while also enhancing player motivation and engagement. Full article

While much of the current research on early specialization focuses on physical outcomes, training models, and policy implications, little is known about how athletes themselves make sense of their developmental experiences. This study aims to examine how ice hockey players perceive and experience early specialization within competitive youth sport contexts, with the goal of generating a nuanced, inductively grounded understanding of athlete development from the athlete perspective. A qualitative study design was used where eight current and former ice hockey players with experience of early specialization participated. Data were collected using semi-structured interviews and analyzed using qualitative conventional content analysis. Three overarching themes emerged, highlighting experiences of loneliness, pressure, and elevated expectations within elite sport environments, alongside the vital importance of support networks and team community: ‘Thrown into adulthood with premature expectations’, ‘Balancing Support and Pressure in Athlete Development’, and ‘The Struggle Between Dream and Reality’. Players described feeling pressured, isolated, and prematurely professionalized, often at the expense of personal development. The findings highlight the psychological and structural challenges of early specialization in elite ice hockey. While support systems played a crucial role, they also contributed to performance anxiety and external expectations. These insights underscore the need for youth sport systems that prioritize long-term athlete well-being over short-term success. Full article

Background: Preseason screening is widely used in handball to identify athletes at increased risk of injury, yet the prognostic value of different screening approaches remains unclear. The aim of this study was to systematically review the evidence on preseason screening tests and physical assessments in relation to subsequent injury outcomes in handball players. Methods: A systematic review was conducted according to PRISMA guidelines. PubMed, MEDLINE, CINAHL, and Scopus were searched on 14 March 2026. The first 100 results from Google Scholar were also screened, and backward citation searching was performed. Eligible studies included handball players and examined preseason or baseline screening, functional, musculoskeletal, or physical performance assessments in relation to prospectively recorded injury outcomes. Two independent reviewers performed study selection, data extraction, and risk-of-bias assessment using the QUIPS tool. Due to substantial heterogeneity in screening tools, injury outcomes, and follow-up procedures, meta-analysis was not performed. Results: Eight studies were included. Most were prospective cohorts involving adolescent, youth elite, or elite adult handball players. Shoulder-specific screening variables, particularly external rotation strength, strength imbalances, total rotational motion, and selected rotational adaptations, showed more consistent associations with subsequent shoulder-related outcomes. In contrast, broader movement-screening tools, including the Functional Movement Screen, the 9+ screening battery, and the upper quarter Y-Balance Test, generally showed limited associations with overall injury outcomes. Conclusions: Shoulder-specific preseason assessments may be more closely associated with subsequent shoulder-related outcomes than broader movement-screening tools, although the available evidence remains limited, heterogeneous, and derived exclusively from observational studies. Full article

This study examined long-term neuromuscular and multidirectional speed development in elite youth badminton players and evaluated whether developmental stage influences adaptation trajectories during systematic training. Thirty athletes were monitored over 16 months with repeated assessments at five time points and stratified into Younger (8–14 years) and Older (15–22 years) developmental groups. A comprehensive test battery assessed explosive strength, reactive strength, musculotendinous stiffness, and badminton-specific multidirectional speed. Data acquisition was performed using a multi-sensor approach, including force-platform-based jump analysis, accelerometry-based systems, and electronic timing gates, enabling the objective, high-resolution, and repeatable monitoring of neuromuscular performance. Significant time effects were observed across all sensor-derived performance variables (p < 0.001), indicating robust improvements in speed, power, and neuromuscular efficiency. Adaptation trajectories were predominantly linear, with no evidence of performance plateauing. Although older athletes maintained higher absolute performance levels, Time × Group interactions were largely absent, demonstrating parallel improvement rates across developmental stages rather than a catch-up effect in younger players. Linear mixed models confirmed equivalent improvement slopes despite baseline differences, and adjustment for body mass attenuated but did not eliminate age-group differences in jump performance. Exploratory analyses revealed substantial inter-individual variability, identifying responder phenotypes independent of age. These findings indicate that systematically progressed training supports sustained, linear neuromuscular adaptation across youth badminton development and highlight the importance of long-term, individualized monitoring over age-based expectations of accelerated responsiveness. Full article

Soccer goalkeeper diving saves demand precise inter-segmental coordination to intercept shots under uncertainty, yet preparatory postures and kinematic adaptations between declared (D) and undeclared (ND) conditions remain underexplored in youth athletes. This study analyzed lower-limb kinematics and Continuous Relative Phase (CRP) in 10 elite youth male goalkeepers (14.3 ± 0.3 years) performing dives in different conditions using inertial sensors (Xsens MVN Awinda, 60 Hz) on a natural grass pitch. Data were time-normalized across the dive cycle and analyzed using Statistical Parametric Mapping 1D ANOVA to compare kinematic and coordination differences between conditions and preferred side. ND high dives showed significantly shorter total duration (1.02 ± 0.13 s vs. 1.09 ± 0.12 s) and take-off (0.19 ± 0.05 s vs. 0.21 ± 0.05 s) compared to the D condition. Pronounced laterality emerged in hip internal/external rotation (ipsilateral: 0–100%), with CRP alterations only in the ipsilateral ankle-hip/knee during preferred-side low dives (13–74%, p < 0.001), indicating tighter segmental coupling and reduced phase lag between joints from mid-stance to push-off. D condition appeared to favor mediolateral CoM shifts for reach optimization, while ND emphasized anteroposterior readiness. These findings highlight CRP’s sensitivity to coordination under uncertainty and reveal laterality effects in preferred-side low dives. Full article

Early adolescent sport dropout is commonly explained through individual psychological factors such as declining motivation, burnout, or identity conflict. While valuable, these accounts often assume parental logistical and financial support as a stable background condition. This conceptual article introduces the Utilitarian Shift as a novel, family-level structural mechanism that helps explain why sport dropout peaks during early adolescence. Drawing on Social Exchange Theory, sociological perspectives on family investment, and developmental psychology, the framework conceptualizes dropout as emerging from a developmentally timed recalibration of parental investment. During childhood, parental support is largely sustained by custodial and broad developmental incentives; however, as adolescents gain functional independence and perceived developmental returns decline, continued investment becomes conditional rather than assumed. At the same time, sport system demands intensify through specialization pressures, rising costs, and selection mechanisms such as the Relative Age Effect. The convergence of declining perceived returns and escalating costs prompts rational parental withdrawal of logistical and financial support, thereby dismantling the material infrastructure required for sustained participation. Importantly, this withdrawal precedes and reshapes adolescents’ capacity to enact motivation, agency, and resilience, rather than merely responding to disengagement. The article situates early adolescent sport dropout as a relational and structurally mediated process, shifting analytic attention away from athlete-centered deficit models toward dynamic parental decision-making within marketized youth sport systems. Practically, the framework highlights the need for sport organizations and governing bodies to redesign participation pathways and value propositions that sustain parental engagement during early adolescence, even in the absence of elite performance trajectories. Full article

Monitoring adolescent team-sport athletes may benefit from combining performance and molecular markers, but empirical evidence supporting this approach in youth team sports remains limited. Objective: Our study investigated molecular and physiological adaptations to seasonal training in elite U18 ice hockey players, focusing on aerobic capacity, salivary cortisol, serum irisin, and cell-free DNA (cfDNA) dynamics. Methods: National-level U18 players were enrolled in our study (n = 23 for cross-sectional analysis, n = 12 longitudinal) during the pre- and early-competition season. Aerobic performance was assessed via graded treadmill VO₂max testing, and the biochemical markers quantified using ELISA-based assays. Results: From pre- to early-season (paired n = 12), VO₂max increased by 10.6% (g = +1.00, p = 0.003) and irisin by 14.7% (g = +0.83, p = 0.010). cfDNA decreased by 60.8% (g = −0.54, p = 0.070; moderate effect, not statistically clear), while cortisol remained stable (+11.3%; p = 0.667). Inter-individual variability increased for VO₂max and irisin and decreased by 82% for cfDNA. Exploratory cross-sectional positional analysis indicated higher irisin levels in forwards and elevated cfDNA in defensemen, although differences did not reach statistical significance. Conclusions: These preliminary findings provide cohort-size limited longitudinal evidence of chronic irisin elevation in ice hockey players and highlight the possibility of combining VO₂max + irisin + cfDNA to assist individualized load/recovery in elite youth ice hockey. Full article

Hip and groin injuries are common in elite football, and reduced isometric adductor strength has been identified as a key risk factor. Therefore, reliable and valid field-based methods for assessing hip adduction strength are essential for effective monitoring and injury prevention. This study aimed to evaluate the intra-rater reliability and construct validity of a hand-held dynamometer (HHD) compared with the ForceFrame (FFS) during the adductor squeeze test in elite youth football players. Thirty-eight male academy athletes completed two testing sessions four weeks apart, performing maximal isometric adductor squeezes using both devices. Relative reliability was assessed using intraclass correlation coefficients (ICC), and construct validity was evaluated using paired t-tests, Bland–Altman analysis, and linear regression. The HHD demonstrated excellent intra-rater reliability (ICC = 0.90, 95% CI: 0.82–0.95) and the FFS showed good reliability (ICC = 0.85, 95% CI: 0.71–0.92). Paired t-tests revealed no significant differences between devices, and regression analysis confirmed no proportional bias, indicating strong agreement and construct validity. These findings demonstrate that the HHD provides valid and reliable measurements of isometric hip adduction strength and may serve as a practical, portable, and cost-effective alternative to fixed dynamometry for field-based strength assessment, rehabilitation monitoring, and injury-prevention screening in elite football environments. Full article

Body composition, bone mineral density, and cardiopulmonary exercise testing (CPET) are commonly used to assess aerobic fitness in athletes, but their interrelationships remain unclear. This study compared these parameters by sex and examined their associations in elite athletes. Our study included 145 youth water polo players (age: 15.7 ± 1.6 years; male: 75). Body composition was measured by DEXA, and treadmill CPET was performed using a sport-specific protocol. We analysed the correlations between the following factors by multivariate linear regression: lean body mass (LBM, LBM_index); body fat mass (BFM); percent body fat (PBF); bone mineral content (BMC); lumbar, femoral, and radial bone mineral density (LBMD, FNBMD, FTBMD, RBMD); exercise time; absolute and relative maximal oxygen uptake (VO_2absmax, VO_2relmax); maximal ventilation (VE_max). Exercise time was found to be negatively correlated with BFM, while VO_2relmax was found to be negatively correlated with BFM and PBF. VO_2absmax was found to be positively correlated with BFM, LBM, BMC, FNBMD, and RBMD. VE_max was found to be positively correlated with LBM and LBM_index. In males, VO_2absmax and VE_max were found to be positively correlated with LBMD and FTBMD. Correlations between bone density and CPET proved to be stronger in males. Our results indicate that body composition and bone density parameters influence CPET parameters, and their complex evaluation can support personalized diagnostics and athletes’ health. Full article

The purpose of this systematic review and meta-analysis (PROSPERO ID: CRD42024575181) was to quantify the relationships between dispositional and situational achievement goal involvement and sport confidence. A secondary purpose was to examine potential moderators of these relationships. Published studies reporting sufficient data, including one achievement goal measure from the dichotomous framework and one measure of sport confidence in an athlete sample, were included. Information sources included EBSCOhost databases, Web of Science databases, and relevant meta-analyses. The random-effects correlational coefficient (r) served as the summary statistic. Thirty-six studies yielding 37 independent samples, published between 1988 and 2026, which met all inclusion criteria, representing a total of 10,461 participants from youth to elite sports across four continents. Meta-analyzed random-effects correlations between task climate (k = 15, r = 0.33 [95% CI 0.23, 0.43]), ego climate (k = 13, r = −0.08 [95% CI −0.16, −0.00]), task orientation (k = 26, r = 0.27 [95% CI 0.21, 0.32]), ego orientation (k = 26, r = 0.11 [95% CI 0.06, 0.17]), and sport confidence ranged from small and negative to medium and positive in magnitude. Mixed-effects moderator analyses revealed significant differences (p < 0.05) for task climate when comparing state (r = 0.24) versus trait (r = 0.41) sport confidence measures, for task orientation scale (TEOSQ r = 0.31 vs. POSQ r = 0.18) in relation to sport confidence, and for study quality (lowest r = 0.35, medium r = 0.18, highest r = 0.24) in the task orientation–sport confidence relationship. However, nearly all prediction intervals for the examined relationships crossed zero, with the exception of a few TEOSQ- and POSQ-based moderator analyses. Thus, researchers and practitioners are cautioned that relationships between dispositional achievement goals, motivational climate perceptions, and sport confidence might be minimal or vary based on the dispositional achievement goal measure. Full article

Background: Monitoring training load and recovery is essential for performance optimization and injury prevention in youth football. However, predicting subjective recovery in preadolescent athletes remains challenging due to biological variability and the multidimensional nature of training responses. This exploratory study examined whether supervised machine learning (ML) models could predict Total Quality of Recovery (TQR) using integrated external load, internal load, anthropometric and maturational variables collected over one competitive microcycle. Methods: Forty male sub-elite U11 and U13 football players (age 10.3 ± 0.7 years; height 1.43 ± 0.08 m; body mass 38.6 ± 6.2 kg; BMI 18.7 ± 2.1 kg/m²) completed a microcycle comprising four training sessions (MD-4 to MD-1) and one official match (MD). A total of 158 performance-related variables were extracted, including external load (GPS-derived metrics), internal load (RPE and sRPE), heart rate indicators (U13 only), anthropometric and maturational measures, and tactical–cognitive indices (FUT-SAT). After preprocessing and aggregation at the player level, five supervised ML algorithms—K-Nearest Neighbors (KNN), Support Vector Machine (SVM), Decision Tree (DT), Random Forest (RF), and Gradient Boosting (GB)—were trained using a 70/30 train–test split and 5-fold cross-validation to classify TQR into Low, Moderate, and High categories. Results: Tree-based models (DT, GB) demonstrated the highest predictive performance, whereas linear and distance-based approaches (SVM, KNN) showed lower discriminative ability. Anthropometric and maturational factors emerged as the most influential predictors of TQR, with external and internal load contributing modestly. Predictive accuracy was moderate, reflecting the developmental variability characteristics of this age group. Conclusions: Using combined physiological, mechanical, and maturational data, these ML-based monitoring systems can simulate subjective recovery in young football players, offering potential as decision-support tools in youth sub-elite football and encouraging a more holistic and individualized approach to training and recovery management. Full article

Background: Despite many young players showing strong potential, only a small fraction succeeds in the critical transition from youth to elite senior football. This scoping review synthesizes research on the junior-to-senior transition in men’s football, identifying main topics related with barriers and facilitators in the transition. Methods: Searches were performed in four databases (PubMed, Scopus, SPORTDiscus, and Web of Science) according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA, 2020) guidelines, using the following keywords: “football*” OR football AND talent* OR “talent identification” OR “talent development” OR expert* OR gift* AND “junior-to-senior” OR “transition career” or “athlete career transition” OR “transition phase”. Original articles in English focused on the junior-to-senior process in male footballers were included. Results: From 5307 titles, 35 studies met eligibility criteria. The most examined themes were psychosocial factors, including social support, stressors, and resilience. The reviewed studies identified organizational structure and effective club communication as facilitators and emphasized the importance of physical attributes to meet senior-level demands. Conclusions: Overall, the junior-to-senior transition is multifaceted, shaped by psychosocial, organizational, and physical factors. Despite robust research, gaps remain; future longitudinal and interdisciplinary studies should inform evidence-based strategies for optimizing player development and retention. Full article