Performance in table tennis is known to be affected by both mental and physical fatigue. However, accurately predicting a player's fatigue state remains challenging, particularly when using non-intrusive measurement protocols. This study proposes a methodology for detecting fatigue based on the analysis of players' movement patterns following controlled fatigue induction in young elite table tennis players. Player movements were recorded using an instrumented racket equipped with an accelerometer and pressure sensors. Mental and physical fatigue were induced using established protocols and were validated through significant changes in reference markers, including the Rating of Perceived Exertion for mental fatigue (p < 0.05) and Maximum Voluntary Contraction for physical fatigue (p < 0.05). The resulting labelled datasets were used to train supervised machine learning models for both binary fatigue detection and multiclass fatigue classification. Among the evaluated models, K-Nearest Neighbors and Random Forest achieved the best performance, with recognition rates of approximately 84% for binary classification and 82% for multiclass classification. These results demonstrate that combining formal fatigue induction with instrumented movement analysis enables the creation of reliable datasets for predicting players' fatigue states from their gestures.

This study investigated the alignment between external training load metrics and coach-prescribed development goals in an elite youth basketball setting. External training load data from training drills were collected over two years from 25 elite male youth basketball players in a full-time residential academy. At the start of each term, coaches developed and assigned individual developmental goals (IDGs) for each player. Using inductive thematic analysis, these IDGs were retrospectively grouped into four overarching development goal categories (defensive, offensive, skill, and physical) and 16 specific goal types (e.g.,cutting, shooting, and load tolerance). Separately, external load metrics were recorded during all on-court training sessions using Catapult Vector S7 devices. To align IDGs with external load metrics, two multinomial logistic regression models were developed to classify (1) development goal category and (2) specific goal type (SGT) using per-minute external load metrics. Both models achieved 66% classification accuracy (Kappa=0.60). Key predictors, such as high-intensity deceleration counts, vertical PlayerLoad, and high-speed running distances, were retained in both models following stepwise selection. Model performance was strong, with large reductions in AIC (ΔAIC=1224.1 and 2540.7, respectively), demonstrating that coach-assigned IDGs were associated with distinct external load profiles. Additionally, accumulated training time differed significantly across specific goal types, reflecting systematic variation in emphasis across the season. These findings demonstrate that external training load metrics reflect the structure of coach-assigned development goals, offering a data-driven framework to evaluate alignment between training design and physical demands in youth basketball.

The aim of this study was to guide the selection of load variables assessed within an elite-level academy player monitoring program through the application of a conceptual framework based upon previous literature and expert opinion. The variables identified by the framework were then subjected to a principal component analysis (PCA) to help verify the consistency of metrics retained across different age groups, the amount of variance described, and differences between absolute and relative load measures. Training and match data recorded by 145 elite youth soccer players from Under 15 to Under 19 squads were assessed across 2 full competitive seasons. The conceptual framework identified 16 metrics for the absolute PCA and 14 for the relative PCA. The results identified 3 to 4 components that contained distinct themes that were consistent across the different age groups assessed and aligned closely with the constructs of load identified through the conceptual framework. The variance of load described by different components (13.8%-29.3%) was similar across each age group. These findings indicate that a myriad of factors is required to describe the variance in load experienced by elite youth soccer players and supports the inclusion of both external and internal loads. The general themes identified by the conceptual framework and retained by the PCA can aid practitioners to identify variables that should be incorporated in youth soccer players load monitoring.

The purpose of this study was to compare the differences in physical fitness between different ranked and age youth basketball players. 382 youth basketball players (U18: n = 190; U17: n = 192) participated in the study. Players` sprint, vertical jump, standing long jumps, sit-ups, sit-and-reach and shuttle run were tested before National Tournament Camp. And players were divided into the top 50% and bottom 50% based on team ranking in the tournament table. Independent T test with effect size was used for analysis. Overall, physical fitness profiles were largely similar between U17 and U18 players. U17 players were significantly faster than the U18 players in sprint and shuttle run (p < 0.05, d=-0.60 to -0.87), and their vertical jump was significantly lower than that of U18 players (p < 0.05, d=-0.31). Regarding different rankings, the U17 top ranking players were significantly faster than the bottom ranking players in sprinting speed (p < 0.05, d=-0.29) and had a significantly higher vertical jump height (p < 0.05, d = 0.36) than the bottom ranking players. Besides, all physical abilities were significantly different between positions (p < 0.05) except for sit-and-reach (p > 0.05). These findings indicate that physical fitness characteristics are broadly comparable between elite U17 and U18 basketball players, suggesting that major physical development may have largely stabilized by late adolescence. Positional demands appear to exert a stronger influence on fitness profiles than chronological age or team ranking at this stage.

Introduction and purpose: Overtraining syndrome (OTS) might occur in athletes experiencing extreme physical and mental stress over a longer period of time without adequate recovery (Meeusen et al., 2013). A decrease in sports performance and chronic fatigue are the most frequent symptoms (Carrard et al., 2021; Meeusen et al., 2013). Reliable diagnostic and monitoring tools are lacking but are strongly needed due to the high prevalence of OTS of 5 to 64 % (depending on definition and sample) and its potential reducing risk of injury (Meeusen et al., 2013). We aimed to develop novel sex-specific, non-invasive and multiparametric recovery monitoring models. Methods: Seventy-three youth and young adult elite athletes (51 females, age 19.7 ± 4.0 years) from mainly team and speed/power-oriented sports, e.g., handball and athletics, participated. Weekly measurements were conducted over 16 weeks to assess the athletes’ recovery state, resulting in 663 measurement timepoints. Forty parameters – including sleep, training load, occupational load, social load, menstrual cycle, heart rate and heart rate variability (HRV), core body temperature, grip strength, and single and double leg jump performance – served as predictors of the athletes’ subjective rating of recovery and stress (Short Recovery and Stress Scale, SRSS, Kellmann &amp; Kölling, 2020). Lasso, Ridge, and Elastic Net regularized regression was applied for automated parameter selection, training, and cross-validation of the binomial prediction models. Results: For the female athletes’ model AUC = 0.819 was calculated (sensitivity = 79.8%, specificity = 72.9%). Thereby, the parameters social load, single and double leg jump performance, sleep quality, training load, grip strength, and occupational load were ranked within the top ten highest predictive parameters (Figure 1). The male athletes’ model demonstrated similar predictive performance with AUC = 0.797 (sensitivity = 74.3%, specificity = 71.4%). Thereby, grip strength, HRV, single leg jump performance, and social load were among the top ten most predictive parameters. Discussion: A broad and novel combination of non-invasive parameters was analysed to capture a holistic picture of the athletes’ recovery and stress state. The resulting sex-specific models showed good predictive performance. The development of sex-specific recovery monitoring prediction models seemed crucial due to the observed differences in parameter importance. Conclusion: This study provides a deeper understanding of the relevance of specific parameters for recovery and stress monitoring in female and male youth and young adult elite athletes.

A Comment on "Evaluating the Reliability and Seasonal Sensitivity of a Fitness-Testing Battery in Elite Youth Soccer".

This study examined the acute effects of four structured warm-up protocols "FIFA 11+", PEP, HarmoKnee, and a "dynamic warm-up" on phase-specific countermovement jump (CMJ) performance and neuromuscular activation patterns in elite youth soccer players. Nineteen male athletes (15.1 ± 0.1 years) completed each protocol in a randomized crossover design, with CMJ analysis focusing on the eccentric, concentric, and landing phases. Kinematic (knee joint angles), kinetic (peak vertical ground reaction forces), and electromyographic (EMG) measurements of the vastus lateralis (VL) and semitendinosus (ST) activation were synchronized during CMJ execution. FIFA 11 + demonstrated superior acute effects across all CMJ phases: during the eccentric braking phase, eliciting greater knee flexion angles (p < 0.05) and higher VL pre-activation. The concentric propulsion phase showed a 12.6% greater peak force (1434.63 ± 175.86 N vs. 1340.31 ± 135.99 N after dynamic warm-up, p = 0.001) and 11.2% higher jump height (35.95 ± 1.89 cm vs. 31.92 ± 1.64 cm, p = 0.011); during landing, there was a 24.9% greater impact force absorption (4331.99 ± 128.73 N vs. 3468.05 ± 96.19 N, p < 0.001) with more balanced ST activation. EMG analysis revealed FIFA 11 + protocol induced significantly higher muscle activation than other protocols throughout all CMJ phases (VL: 21-28% increase; ST: 18-25% increase; both p < 0.01), particularly during the eccentric-concentric transition phase (0.20 ± 0.03 s vs. 0.28 ± 0.04 s after dynamic warm-up). These phase-specific enhancements suggest that the FIFA 11 + protocol enhances the neuromuscular system for rapid force production and absorption more effectively than other warm-up routines. The findings support the use of structured neuromuscular warm-ups for optimizing acute performance, although future longitudinal studies should examine their cumulative effects on injury prevention.

This study aimed to investigate the effectiveness of a single session of high-pressure intermittent pneumatic compression (IPC) on post-match recovery in international level youth soccer players, using neuromuscular, biochemical, and perceptual markers. Forty-two observations (across 6 matches) of 23 elite U19 soccer players (age: 17.45 ± 0.72 years; height: 1.82 ± 0.06m; body mass: 74.95 ± 6.45kg) participated in this randomized, placebo-controlled trial. Following competitive matches, participants were assigned to receive either 30min of high-pressure IPC (200 mmHg) or a placebo intervention (hydrant cream). Recovery status was assessed pre-match, and at 30min, 24- and 48-hours post-match using countermovement jump height, low-frequency fatigue of the knee extensors (Myocene®), creatine kinase (CK) concentrations, and self-reported fatigue and soreness. Linear mixed models were used to examine the effects of time, group, and time x group interaction. Covariates such as perceived exertion, GPS metrics, and sleep metrics were included when appropriate. No significant time x group interactions were found for any of the variables under analysis (p = 0.089 to 0.834). Significant main effects of time were detected in CK, perceived fatigue and soreness (p < 0.001), confirming match-induced fatigue, but without group differences. Exploratory analyses revealed that internal and external load, as well as total sleep time influenced recovery markers, particularly CK and perceptual responses. A single session of high-pressure IPC does not seem to enhance post-match recovery in elite youth soccer players compared to a placebo, on neuromuscular, biochemical, and subjective markers. ClinicalTrials.gov code NCT06636942 (date of registration: 02/10/2024).

Somatotype has been linked to physical performance in youth athletes, but its independent contribution to power development, particularly in relation to biological maturity, remains underexplored. This study examined whether somatotype and age independently influence neuromuscular performance in elite youth football players and whether these effects persist after normalization for body mass. A total of 106 elite male academy players aged 15 to 18 years were classified as mesomorphic or ectomorphic using the Heath-Carter method. Performance tests included vertical jumps from a squat position and with countermovement, lower-limb peak power (estimated via a validated field equation), and an index estimating stretch-shortening cycle efficiency. Relative power (W·kg-1) was also calculated to account for body-mass dependence. Analyses included multivariate and variance testing, to explore independent effects of somatotype and age. Mesomorphic players produced significantly higher power output than ectomorphic players; older athletes also exhibited greater power. No interaction was observed between somatotype and age group. However, when normalized to body mass, between-group differences were no longer significant, indicating that the apparent mesomorphic advantage reflected greater mass rather than superior neuromuscular efficiency. No significant somatotype effect was observed for the Elasticity Index (P=0.098). Logistic regression correctly classified 72.6% of somatotypes, but specificity for ectomorphs was very low (11.5%), indicating that power-based profiling is ineffective for identifying ectomorphic players. Somatotype and age independently influence power performance in elite youth football players. Nevertheless, relative power analysis demonstrated that morphological differences primarily underlie these effects. Power metrics alone lack diagnostic validity for morphological classification and should complement, rather than replace, anthropometric assessment.

ABSTRACT Elite youth sport increasingly demands year-round participation, yet family-level impacts remain under-researched. This study examined the impact of elite club volleyball on key areas of family functioning among 446 parents nationwide. Nearly all athletes (96%) specialized in volleyball, with 90% starting before age 14. Most families (88%) reported substantial time demands and 62% spent over $5,000 annually. While parent-athlete relationships strengthened (81%), spousal relationships (12%) and sibling activities (41%) were negatively affected. Higher parental stress correlated with perceived excessive club expectations and negative family outcomes. Financial burden predicted relationship strain independently of stress. Findings reveal that elite club volleyball restructures family systems, strengthening some relationships while straining others. Critical gaps remain in coach education programs. As youth sport continues to evolve, coach education programs should be intentional about broadening the scope of their curriculum to address the challenges of today’s elite youth sport parent.

This study compares the physical demands between two age categories (U18 and U21) during different types of sided games (small, medium, and large) based on relative pitch area (RPA). Thirty-seven elite youth soccer players from two late-stage academy teams participated in small-sided games (SSGs) over 9 weeks. Distances covered at different speed intensities (total distance, high-speed running distance, and sprinting distance) and the number of accelerations and decelerations were analyzed. Multilevel analyses revealed significant differences in physical performance between age categories. The U21 team covered significantly more high-speed running and sprinting distances, while the U18 team performed more accelerations and decelerations. Large-sided games resulted in the greatest total distance, high-speed running and sprinting, while small-sided games produced the most accelerations and decelerations. The findings suggest age-related differences in physical performance, particularly in medium- and large-sided games, with older players covering greater distances at higher speeds. These differences may be due to biological maturation and could also be influenced by tactical behavior. This study contributes to understanding the physical performance variations among elite late-stage academy soccer players, emphasizing the impact of age category and game format. Insights into manipulating RPA are crucial for coaches to optimize training sessions and facilitate the physical transition between late-stage academy teams.

The February 2026 Children’s orthopaedics Roundup 360 looks at: Fixation techniques for tibialis anterior tendon transfers for clubfoot; Posterior tibial slope in adolescents with anterior cruciate ligament tears; Perfusion MRI for predicting avascular necrosis for surgical hip reduction in developmental dysplasia of the hip; Outcomes following extra-articular subtalar fusion for children with cerebral palsy; A Frailty Index for predicting complications and mortality following adolescent spinal surgery; Apophyseal injuries in elite youth football academies; Should we be removing plates following varus derotation osteotomy to minimize fracture risk?; Confidence and surgical volume during paediatric orthopaedic training in the UK.

Olthof, SBH, Ferrandis, J, de Dios, V, and Riboli, A. Pitch size, player numbers, and playing rules: how small-sided game constraints shape the training demands in male academy soccer. J Strength Cond Res XX(X): 000-000, 2026-Small-sided games (SSGs) are part of daily soccer practice and usually manipulated in pitch size, player number, and playing rules. The aim of this study was to identify constraints that significantly affect the physical demands in SSGs in youth elite soccer players. Training sessions from an under-18 Spanish academy team were monitored, including 87 SSGs. Small-sided games were labelled for area per player (ApP), number of players, type of game, playing duration, goal size, use of floater players and goalkeepers, and number of touches. Relative physical demands were measured as total distance (TD), high-speed running (HSR), sprint distance (SD), and acceleration (ACC) and deceleration (DEC) distance. A linear mixed-effects model analysis was performed estimating the effects of SSG constraints (α set at 0.05). Greater ApP consistently increased TD, HSR, SD, ACC, and DEC. By contrast, increasing the number of players and longer playing duration reduced TD, HSR, ACC, and DEC. In addition, specific playing rules, such as the use of floater players, limited touches, and small goals primarily affected ACC and DEC. These findings highlight the important role of ApPs in shaping physical demands, while also showing that team size, playing duration, and specific playing rules contribute to the physical demands of SSGs. Understanding the magnitude and direction of these manipulations allows coaches to design SSGs more effectively to meet training objectives.

Attempting to suppress unwanted thoughts is generally characterized by the opposite outcomes of what is desired in motor task performance, resulting in a counterintentional error. The study examined the impacts of priming negative cues on elite athletes' performance in Stroop rifle shooting task, guided by ironic processes of mental control theory (Wegner, 1994). Ten elite youth biathletes performed the task under two conditions: Low-Cue Frequency (LCF) and High-Cue Frequency (HCF) using a quasi-experimental within-subject design. Using multiple psychophysiological measures, the study assessed ironic errors, non-ironic errors, target hits, and reaction times (RTs) at the incongruent stimuli. Across both conditions, repeated negative priming cues did not lead to ironic shooting errors or delays in target responses-contradicting Wegner's (1994) assumption about ironic errors. Bayesian analysis revealed moderate and anecdotal evidence in support of the null model (BF01) for target hit rates and RTs towards target hits, respectively. Heart rate (HR) and heart rate variability (HRV) also showed no significant variations across conditions. Findings suggest that negative instructions, regardless of frequency, do not disrupt elite biathletes' shooting performance. Directives like "do not shoot [specific color]" fail to induce ironic errors, highlighting elite biathletes' resilience to such cues in maintaining consistent shooting performance.

With the growing demands and expectations associated with professionalised youth sport environments, there is an increasing need for psychosocial development initiatives to support young athletes and their healthy progression. The aim of this study was to extend and investigate the application of the 5Cs framework, a prominent psychoeducational approach in sport psychology, to a youth tennis Talent Development Environment (TDE). Using a collective case study design, five athletes, their parents and two coaches (n = 12) participated in a season-long multimodal 5Cs intervention programme at a British Regional Player Development Centre (RPDC). The 30-week programme was delivered by an embedded sport psychology practitioner (SPP) and incorporated a blocked educational curriculum supported by a range of athletes, coach and parent development strategies. Post-intervention semi-structured interviews were conducted with all participants, with reflexive thematic analysis leading to three overarching themes. Findings highlighted the positive influence of the programme, with perceptions of the framework's effectiveness associated with its specificity to tennis and individual athlete needs, the collaboration of all stakeholders across the TDE and the use of developmentally accessible and innovative strategies enabling evidence of athlete improvements. Researchers, practitioners and sport organisations are encouraged to consider these impact factors in terms of supporting the development, performance and well-being of athletes and their families in competitive youth sport contexts.

The study investigated the relationship between external and internal training load measures in 25 male elite youth soccer players (age: 16.6 ± 0.9 years, VO2max: 59 ± 4 ml/min/kg) over 3 months. External load (i.e., total distance, high metabolic power distance, high-speed running) was quantified using a local positioning system and related to subjective (RPE, sleep quality, drive (energy level)), biochemical (creatine kinase (CK), lactate dehydrogenase (LDH), C-reactive protein (CRP), urea, cortisol, transferrin), and neuromuscular (CMJ) markers. Single day workload (1DL), exponential 7-day workload (7DL), and the acute: chronic workload ratio (ACWR) were calculated. 1DL parameters were correlated (Spearman’s rho) with RPE (range r = 0.24 to 0.43, p < 0.01) and 1DL distance was negatively related to drive (r = − 0.28, p < 0.001). LDH correlated positively with training load across all calculation methods (up to r = 0.27, p < 0.01). CK exhibited positive correlations to ACWR training load (r = 0.23 to 0.27, p < 0.05), while transferrin (ACWR) and CRP (1DL) showed negative associations to training load (r = − 0.21 to − 0.28, p < 0.05). CMJ eccentric mean force was negatively correlated with all ACWR training load variables (r = − 0.22 to − 0.25, p < 0.01). In summary, subjective measures showed stronger and more consistent associations with training load than biomarkers or neuromuscular testing. Practitioners may confidently use well-structured questionnaires for load monitoring in elite youth soccer.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-31487-z.

Through 19 in-depth interviews with youth academy coaches at different levels, this study investigates the acceptance of mobile devices among elite youth football coaches in Germany, focusing on the integration of smartphones and tablets for on-pitch use. While mobile devices provide opportunities for live tracking, video feedback, and performance monitoring, their adoption remains influenced by traditional coaching norms and organizational limitations. Using the Technology Acceptance Model (TAM), this research explores coaches’ perceptions of usefulness and ease of use, examining factors such as subjective norms, structural barriers, and resource availability. Findings reveal that while many coaches recognize the value of technology for individualized player development, the devices are typically viewed as supplementary to traditional methods. Social expectations, resource constraints, and device-specific challenges continue to shape coaches’ willingness to integrate mobile tools, highlighting the need for targeted support to enhance the effective use of technology in youth coaching.

Background and Objectives: This study compared the effects of two posterior-chain strength training strategies on eccentric hamstring strength, jump and sprint performance, and hamstring injury incidence in elite youth soccer players. Materials and Methods: Twenty-three players were randomly allocated to either a Nordic Hamstring Exercise Group (NHEG; n = 11) or a Deadlift + Leg Curl Slides Group (D + LCSG; n = 12). Both groups completed a 9-week in-season resistance training program consisting of one strength-oriented session (MD-4) and one power-oriented session (MD-2) per week, in addition to regular soccer training. Pre- and post-intervention assessments included eccentric hamstring strength (NordBord), countermovement jump (CMJ), and 10 m and 30 m linear sprint performance. Results: Eccentric hamstring strength increased significantly only in the NHEG (p ≤ 0.05), though this improvement did not transfer to enhancements in jump or sprint performance (p > 0.05). No significant changes were observed in the D + LCSG for any variable (p > 0.05), and no between-group differences were found across all performance outcomes. During the 12-week monitoring period, one hamstring injury was recorded, occurring in the NHEG. Conclusions: These findings suggest that, while the NHE elicited greater exercise-specific eccentric strength gains, neither posterior-chain strategy produced improvements in sprint or jump performance. However, given the small sample size and low number of injury events, these trends cannot be attributed with certainty to the implemented protocols, and both programs reported a low incidence of hamstring injuries per 1000 h of exposure with no statistically protective effect associated with the use of the NHE.

The purpose of this cross-sectional study was to evaluate associations among injury, quality of life (QOL), and mental health among elite youth soccer athletes. Study materials were sent to Elite Clubs National League (ECNL) clubs through an online survey link. Soccer athletes were invited to participate in May and June of 2024 by their respective clubs. Six hundred sixty-eight ECNL soccer athletes (ages 13-19 years) completed the study. Injury history and risk factors were assessed using a demographic survey. Outcomes including QOL (Pediatric Quality of Life Inventory), anxiety (General Anxiety Disorder-7), and depression (Patient Health Questionnaire-9) were compared between athletes by injury status (uninjured, recovered, injured) using Tukey-adjusted pairwise comparisons of estimated marginal means. Two hundred ninety-five (44.2%) respondents reported an injury in the prior 6 months, of whom 224 (33.5%) had recovered, and 71 (10.6%) were currently injured. Uninjured athletes reported significantly lower symptoms of anxiety (5.0, 95% CI [4.5-5.5]) than currently injured (6.6 [5.5-7.7], P = 0.008) and recovered athletes (6.0 [5.3-6.6], P < 0.001). Currently injured athletes reported higher levels of depression (6.9 [5.8-8.1]) than recovered (5.2 [4.5-5.8], P = 0.01) and uninjured athletes (4.6 [4.0-5.1], P < 0.001), while the difference between recovered and uninjured athletes was not statistically significant (P = 0.19). Uninjured athletes also demonstrated significantly higher total QOL (81 [80-82]) than recovered (79 [77-80], P = 0.021) and currently injured (73 [70-76], P < 0.001) athletes. Injured youth soccer athletes report worse mental health and QOL than uninjured athletes, even after return to play. Stakeholders in youth sports should consider that negative psychosocial impacts of injury may persist beyond physical impacts.

To assess total, weekly, and session rating of perceived exertion (sRPE) training load (TL), identify factors influencing sRPE-TL, and analyze interplayer, individual relative-to-team, and intraplayer variability in elite youth female footballers. All outfield players (age 13.7 [0.5]y) from the U14 (under 14 y of age) team of a Spanish Women's First Division academy were monitored over a 19-week competitive period. Players reported sRPE after each training session and match. TL was calculated as sRPE × session duration. Individual- and team-level analyses were performed. Players completed 95% (4%) of sessions. Total and weekly team sRPE-TL averaged 19,717 (1708) and 1200 (104)AU (arbitrary units), respectively. Playing position had no significant effect (P > .05), whereas training day significantly influenced session TL (P < .001), with matches showing substantially lower TL than training sessions (Cohen d: 2.85-4.34). Interplayer variability was small to moderate (coefficient of variation 7%-14%). Differences between individual and team means ranged from -26% to +25%, trivial to very large. Intraplayer variability was moderate to very large (coefficient of variation 10%-53%), with session-level variability classified as very large for all players. The interaction between individual-team difference and intraplayer variability was analyzed. Despite consistent team-level TL, marked individual differences emerged. Two individual TL profiles were identified: (1) mean-aligned versus mean-divergent and (2) stable versus unstable. Combining both dimensions enhances individual TL profiling and supports tailored training strategies. These findings emphasize the need to move beyond team averages to ensure appropriate monitoring and individualized development in elite youth female football.