Kinship and similarity drive coordination of breeding-group choice in male spotted hyenas.

When and where animals reproduce influences the social, demographic and genetic properties of the groups and populations they live in. We examined the extent to which male spotted hyenas (Crocuta crocuta) coordinate their breeding-group choice. We tested whether their propensity to settle in the same group is shaped by passive processes driven by similarities in their socio-ecological background and genotype or by an adaptive process driven by kin selection. We compared the choices of 148 pairs of same-cohort males that varied in similarity and kinship. We found strong support for both processes. Coordination was highest (70% of pairs) for littermates, who share most cumulative similarity, lower (36%) among peers born in the same group to different mothers, and lowest (7%) among strangers originating from different groups and mothers. Consistent with the kin selection hypothesis, the propensity to choose the same group was density dependent for full siblings and close kin, but not distant kin. Coordination increased as the number of breeding females and male competitors in social groups increased, i.e. when costs of kin competition over mates decreased and benefits of kin cooperation increased. Our results contrast with the traditional view that breeding-group choice and dispersal are predominantly solitary processes.

The adolescent motor performance development of elite female soccer players: A study of prognostic relevance for future success in adulthood using multilevel modelling.

Considering the scarce empirical evidence regarding talent predictors in female youth soccer, the present study aimed to investigate the long-term prognostic validity of elite female soccer players' adolescent motor performance for future success in adulthood. Additionally, the three-year development of highly talented girls' motor performance and the predictive value of this motor development for reaching a professional adult performance level (APL) was analysed. Overall, N = 737 female players participated in nationwide motor diagnostics (sprinting, agility, dribbling, ball control, shooting) within the German Soccer Association's talent identification and development programme at least twice between the age groups Under-12 (U12) and U15. Based on their APL at least four years later, participants were assigned to a professional (first German division, 6.2%) or non-professional group (lower divisions, 93.8%). Multilevel regression analyses revealed a general prognostic relevance for the investigated parameters with respect to players' APL. In addition, there was a non-linear improvement in participants' motor performance across all variables from U12 to U15. However, non-significant interactions between APL and these improvements indicate motor performance development itself cannot adequately predict players' future success in adulthood. Findings provide insightful information that can help coaches foster optimal support for young female soccer players' development.

Promotion of physical activity-related health competence in physical education: study protocol for the GEKOS cluster randomized controlled trial.

BACKGROUND: One central goal of physical education in many countries is to empower students to be physically active throughout their lifespan. Physical activity-related health competence (PAHCO) encompasses physical, cognitive, and motivational elements associated with the individuals' ability to be physically active in a health-enhancing way. To date, there is a lack of empirical evidence concerning effective programs and methods to promote PAHCO in physical education. The purpose of this study is to examine to what extent a health and physical fitness-related program that includes learning tasks integrating theoretical and practical elements promotes students' PAHCO in physical education. DESIGN/METHODS: This study is a cluster randomized controlled trial that compares two physical education intervention programs on health and physical fitness (IG-run, IG-game play) with regular physical education lessons (CG-run, CG-game play) in secondary schools in Germany. Forty-eight physical education classes (ninth grade) were recruited and randomly allocated to the four study groups. The intervention programs include six physical education lessons on health and physical fitness and only differ in the type of physical activity that is executed (running and jumping vs. small-sided games). The students' PAHCO is examined both pre- and post-intervention and after 8-12 weeks of follow-up. We also determine various process variables during the intervention period to analyze the intervention fidelity. DISCUSSION: The results of this study provide evidence on whether a combination of theoretical and practical elements in physical education can enhance students' PAHCO. Beyond that, our process analyses will allow differentiated insights into the mechanism of how the intervention programs work. TRIAL REGISTRATION: German Clinical Trials Register (DRKS), DRKS-ID: DRKS00016349 . Retrospectively registered on 10 January 2019.

The Effectiveness of Autonomy Support Interventions With Physical Education Teachers and Youth Sport Coaches: A Systematic Review.

Researchers consider motivation a key determinant of physical activity. In physical education (PE) and youth sport, the more children and adolescents evaluate their teachers and coaches to be autonomy supportive, as opposed to controlling, the more self-determined they are in their motivation. Therefore, it appears valuable to help PE teachers and youth sport coaches optimize their interactions with the individuals they work with. This study was designed to systematically review the literature related to autonomy support interventions with PE teachers and youth sport coaches. After relevant databases were searched and duplicates were removed, 1,523 potentially pertinent articles were found. These were subsequently screened based on specific inclusion criteria. This systematic review process helped identify 21 studies that were included for further analyses. Overall, the interventions were frequently successful in enhancing PE teachers' and youth sport coaches' behavior. Additional research appears justified to foster self-determined motivation among children and adolescence.

Prognostic relevance of motor talent predictors in early adolescence: A group- and individual-based evaluation considering different levels of achievement in youth football.

In the debate about the usefulness of motor diagnostics in the talent identification process, the prognostic validity for tests conducted in early adolescence is of critical interest. Using a group- and individual-based statistical approach, this prospective cohort study evaluated a nationwide assessment of speed abilities and technical skills regarding its relevance for future achievement levels. The sample consisted of 22,843 U12-players belonging to the top 4% in German football. The U12-results in five tests served as predictors for players' selection levels in U16-U19 (youth national team, regional association, youth academy, not selected). Group-mean differences proved the prognostic relevance for all predictors. Low individual selection probabilities demonstrated limited predictive values, while excellent test results proved their particular prognostic relevance. Players scoring percentile ranks (PRs) ≥ 99 had a 12 times higher chance to become youth national team players than players scoring PR < 99. Simulating increasing score cut-off values not only enhanced specificity (correctly identified non-talents) but also led to lower sensitivity (loss of talents). Extending the current research, these different approaches revealed the ambiguity of the diagnostics' prognostic relevance, representing both the usefulness and several pitfalls of nationwide diagnostics. Therefore, the present diagnostics can support but not substitute for coaches' subjective decisions for talent identification, and multidisciplinary designs are required.

Psychometric properties of the motor diagnostics in the German football talent identification and development programme.

The utilisation of motor performance tests for talent identification in youth sports is discussed intensively in talent research. This article examines the reliability, differential stability and validity of the motor diagnostics conducted nationwide by the German football talent identification and development programme and provides reference values for a standardised interpretation of the diagnostics results. Highly selected players (the top 4% of their age groups, U12-U15) took part in the diagnostics at 17 measurement points between spring 2004 and spring 2012 (N = 68,158). The heterogeneous test battery measured speed abilities and football-specific technical skills (sprint, agility, dribbling, ball control, shooting, juggling). For all measurement points, the overall score and the speed tests showed high internal consistency, high test-retest reliability and satisfying differential stability. The diagnostics demonstrated satisfying factorial-related validity with plausible and stable loadings on the two empirical factors "speed" and "technical skills". The score, and the technical skills dribbling and juggling, differentiated the most among players of different performance levels and thus showed the highest criterion-related validity. Satisfactory psychometric properties for the diagnostics are an important prerequisite for a scientifically sound rating of players' actual motor performance and for the future examination of the prognostic validity for success in adulthood.

Links between environmental features and developmental outcomes of elite youth athletes: A cross-sectional study within the German talent pathway.

From a holistic perspective, the talent development environment (TDE) influences not only the athletic development but also the development of personal skills as well as the wellbeing of elite youth athletes. Alongside research on the effects of broader environmental features on athlete-related talent development (TD) outcomes, the importance of the closer social climate (i.e., teammates, coaches, support staff) is also emphasized. Therefore, the purpose of this study was to examine the relationship between environmental features, the social climate and athlete-related TD outcomes (I). Additionally, an exploratory analysis was conducted to investigate the role of motivational climate and psychological safety in the relationship between environmental features and athlete-related TD outcomes (II). To this end, 345 German elite youth athletes completed an online survey assessing their perceptions of environmental features, coach-created motivational climate, and psychological safety as well as wellbeing, performance satisfaction, and life skills development. The results revealed that environmental features (especially long-term development focus, effective coach-athlete communication, and the social network), motivational climate and psychological safety were all significantly associated with the outcome variables. These findings underline the significance of environmental features for athlete-related TD outcomes of young talented athletes in German elite youth sports. However, the results indicated that motivational climate and psychological safety did not have significant indirect effects on the relationship between TDE features and athlete-related TD outcomes. Thus, it remains to be questioned if and what other processes influence this relationship.

Selection-Dependent Differences in Youth Elite Basketball Players' Relative Age, Maturation-Related Characteristics, and Motor Performance.

Purpose: The aim of the present study was to investigate the influence of players' relative age, maturation-related characteristics, and motor performance tests on two different stages of talent selection (regional and national level) in youth elite basketball. Methods: Relative age, maturation-related variables (height, weight, maturity offset, maturity timing) and motor performance (Countermovement jump, Standing long jump, Modified agility T-test, Linear sprint 20 m) of N = 68 male youth basketball players (Mage = 14.39 ± 0.28 years) were assessed during the initial selection tournament for the German U15 national team. Pre-selection biases regarding relative age and maturity timing on the regional level were investigated utilizing one-sample t-tests. Differences in relative age, maturation-related characteristics and motor performance between players selected (n = 27) and non-selected (n = 41) for the youth national team were examined via independent samples' t-tests and logistic regression analyses. Results: Strong pre-selection biases toward early-born and early-maturing players were confirmed on the regional level. Significant advantages in height and weight and higher values in maturity offset and maturity timing were found for selected players. Among the motor variables, only Countermovement jump performance was significantly better in selected players. When controlling for relative age and biological maturation regression models including motor performance variables did not significantly discriminate players' selection status. Conclusion: Coaches working in national, but also preceding selection stages (regional and club level) should raise their awareness to relative age and biological maturation when evaluating players' potential and current (motor) performance.

Data analytics in the football industry: a survey investigating operational frameworks and practices in professional clubs and national federations from around the world.

The use of data and analytics in professional football organisations has grown steadily over the last decade. Nevertheless, how and whether these advances in sports analytics address the needs of professional football remain unexplored. Practitioners from national federations qualified for the FIFA World Cup Qatar 2022™ and professional football clubs from an international community of practitioners took part in a survey exploring the characteristics of their data analytics infrastructure, their role, and their value for elaborating player monitoring and positional data. Respondents from 29 national federations and 32 professional clubs completed the survey, with response rates of 90.6% and 77.1%, respectively. Summary information highlighted the underemployment of staff with expertise in applied data analytics across organisations. Perceptions regarding analytical capabilities and data governance framework were heterogenous, particularly in the case of national federations. Only a third of national federation respondents (~30%) perceived information on positional data from international sports data analytics providers to be sufficiently clear. The general resourcing limitations, the overall lack of expertise in data analytics methods, and the absence of operational taxonomies for reference performance metrics pose constraints to meaningful knowledge translations from raw data in professional football organisations.

Do you have a good all-around view? Evaluation of a decision-making skills diagnostic tool using 360° videos and head-mounted displays in elite youth soccer.

Elite youth players' decision-making skills are considered important predictors of adult performance in soccer. The presentation of 360° videos in head-mounted displays offers new potential for the diagnostic of these skills in talent development programs. This study evaluated a new diagnostic tool using soccer-specific 360° videos for assessing decision-making skills in youth academy (YA) players. The evaluation consisted of players' subjective feedback as well as the analysis of diagnostic and prognostic validity. It was hypothesized that high-level YA players achieve better diagnostic results than regional-level players, and U19 outperform U17 players. Moreover, YA players' diagnostic results should be positively associated with future adult performance level. During the 2018/19 season, N = 48 youth players participated in the diagnostic procedures (split-half reliability r = .78). Participants were shown 54 videos which terminated when the central midfielder received a teammate's pass. Participants were then asked how to best continue playing. The subjective evaluation explored YA players' experiences with the diagnostic tool via quantitative ratings (e.g., "How exciting was the task?", "How involved did you feel in the game situation?") and additional interviews. Diagnostic validity was examined in a balanced cross-sectional 2 × 2-design (performance level x age group) and prognostic validity in a 3-year prospective design. Sensitivity and case-by-case analyses completed the evaluation. The YA players provided positive quantitative ratings regarding their experienced immersion into the environment. Players' qualitative feedback indicated general acceptance of the diagnostic tool as well as it offered recommendations for improvements. Confirming the diagnostic validity, ANOVA revealed significant main effects for performance level (p < .001, η2 = .29) and age group (p < .01, η2 = .14). Contributing to the prognostic validity, the diagnostic results discriminated between YA players achieving a higher and a lower adult performance level ("League 1-4" vs. "League 5 or below") in adulthood (p < .05; d = 0.80). A ROC curve and the AUC showed that the correct assignment to the adult performance levels is possible with a 71% probability. YA players with a high decision-making accuracy had a six times higher chance of playing in "League 1-4". The results demonstrated empirical evidence for the new diagnostic tool in terms of YA players' acceptance and validity coefficients exceeding effect sizes of former studies. The technology provides opportunities to test soccer-specific situations demanding an all-around view that were not testable in former experimental settings. Further technological advancements will enable the realization of improvements recommended by the players. Nonetheless, case-by-case analyses suggest caution in using such a diagnostic as a selection tool in talent development programs.

Scaling-up RADseq methods for large datasets of non-invasive samples: Lessons for library construction and data preprocessing.

Genetic non-invasive sampling (gNIS) is a critical tool for population genetics studies, supporting conservation efforts while imposing minimal impacts on wildlife. However, gNIS often presents variable levels of DNA degradation and non-endogenous contamination, which can incur considerable processing costs. Furthermore, the use of restriction-site-associated DNA sequencing methods (RADseq) for assessing thousands of genetic markers introduces the challenge of obtaining large sets of shared loci with similar coverage across multiple individuals. Here, we present an approach to handling large-scale gNIS-based datasets using data from the spotted hyena population inhabiting the Ngorongoro Crater in Tanzania. We generated 3RADseq data for more than a thousand individuals, mostly from faecal mucus samples collected non-invasively and varying in DNA degradation and contamination level. Using small-scale sequencing, we screened samples for endogenous DNA content, removed highly contaminated samples, confirmed overlap fragment length between libraries, and balanced individual representation in a sequencing pool. We evaluated the impact of (1) DNA degradation and contamination of non-invasive samples, (2) PCR duplicates and (3) different SNP filters on genotype accuracy based on Mendelian error estimated for parent-offspring trio datasets. Our results showed that when balanced for sequencing depth, contaminated samples presented similar genotype error rates to those of non-contaminated samples. We also showed that PCR duplicates and different SNP filters impact genotype accuracy. In summary, we showed the potential of using gNIS for large-scale genetic monitoring based on SNPs and demonstrated how to improve control over library preparation by using a weighted re-pooling strategy that considers the endogenous DNA content.

Value of Magnetic Resonance Imaging for Skeletal Bone Age Assessment in Healthy Male Children.

BACKGROUND: Skeletal bone age assessment for medical reasons is usually performed by conventional x-ray with use of ionizing radiation. Few pilot studies have shown the possible use of magnetic resonance imaging (MRI). PURPOSE: To comprehensively evaluate feasibility and value of MRI for skeletal bone age (SBA) assessment in healthy male children. MATERIALS AND METHODS: In this prospective cross-sectional study, 63 male soccer athletes with mean age of 12.35 ± 1.1 years were examined. All participants underwent 3.0 Tesla MRI with coronal T1-weighted turbo spin echo (TSE), coronal proton density (PD)-weighted turbo spin echo (TSE), and T1-weighted three-dimensional (3D) volume interpolated breath-hold examination (VIBE) sequence. Subsequently, SBA was assessed by 3 independent blinded radiologists with different levels of experience using the common Greulich-Pyle (GP) atlas and the Tanner-Whitehouse (TW2) method. RESULTS: In a mean total acquisition time of 5:04 ± 0:47 min, MR image quality was sufficient in all cases. MRI appraisal was significantly faster ( P < 0.0001) by GP with mean duration of 1:22 ± 0:08 min vs. 7:39 ± 0:28 min by TW. SBA assessment by GP resulted in mean age of 12.8 ± 1.2 years, by TW 13.0 ± 1.4 years. Interrater reliabilities were excellent for both GP (ICC = 0.912 (95% confidence interval [CI] = 0.868-0.944) and TW (ICC = 0.988 (95% CI = 0.980-0.992) and showed statistical significance ( P < 0.001). Subdivided, for GP, ICCs were 0.822 (95% CI = 0.680-0.907) and 0.843 (95% CI = 0.713-0.919) in Under 12 and Under 14 group. For TW, ICCs were 0.978 (95% CI = 0.958-0.989) in Under 12 and 0.979 (95% CI = 0.961-0.989) in Under 14 group. CONCLUSION: MRI is a clinically feasible, rapidly evaluable method to assess skeletal bone age of healthy male children. Using the Greulich-Pyle (GP) atlas or the Tanner-Whitehouse (TW2) method, reliable results are obtained independent of the radiologist's experience level.

Sex roles and sex ratios in animals.

In species with separate sexes, females and males often differ in their morphology, physiology and behaviour. Such sex-specific traits are functionally linked to variation in reproductive competition, mate choice and parental care, which have all been linked to sex roles. At the 150th anniversary of Darwin's theory on sexual selection, the question of why patterns of sex roles vary within and across species remains a key topic in behavioural and evolutionary ecology. New theoretical, experimental and comparative evidence suggests that variation in the adult sex ratio (ASR) is a key driver of variation in sex roles. Here, we first define and discuss the historical emergence of the sex role concept, including recent criticisms and rebuttals. Second, we review the various sex ratios with a focus on ASR, and explore its theoretical links to sex roles. Third, we explore the causes, and especially the consequences, of biased ASRs, focusing on the results of correlational and experimental studies of the effect of ASR variation on mate choice, sexual conflict, parental care and mating systems, social behaviour, hormone physiology and fitness. We present evidence that animals in diverse societies are sensitive to variation in local ASR, even on short timescales, and propose explanations for conflicting results. We conclude with an overview of open questions in this field integrating demography, life history and behaviour.

The impact of a pathogenic bacterium on a social carnivore population.

1. The long-term ecological impact of pathogens on group-living, large mammal populations is largely unknown. We evaluated the impact of a pathogenic bacterium, Streptococcus equi ruminatorum, and other key ecological factors on the dynamics of the spotted hyena Crocuta crocuta population in the Ngorongoro Crater, Tanzania. 2. We compared key demographic parameters during two years when external signs of bacterial infection were prevalent ('outbreak') and periods of five years before and after the outbreak when such signs were absent or rare. We also tested for density dependence and calculated the basic reproductive rate R(0) of the bacterium. 3. During the five pre-outbreak years, the mean annual hyena mortality rate was 0.088, and annual population growth was relatively high (13.6%). During the outbreak, mortality increased by 78% to a rate of 0.156, resulting in an annual population decline of 4.3%. After the outbreak, population size increased moderately (5.1%) during the first three post-outbreak years before resuming a growth similar to pre-outbreak levels (13.9%). We found no evidence that these demographic changes were driven by density dependence or other ecological factors. 4. Most hyenas showed signs of infection when prey abundance in their territory was low. During the outbreak, mortality increased among adult males and yearlings, but not among adult females - the socially dominant group members. These results suggest that infection and mortality were modulated by factors linked to low social status and poor nutrition. During the outbreak, we estimated R(0) for the bacterium to be 2.7, indicating relatively fast transmission. 5. Our results suggest that the short-term 'top-down' impact of S. equi ruminatorum during the outbreak was driven by 'bottom-up' effects on nutritionally disadvantaged age-sex classes, whereas the longer-term post-outbreak reduction in population growth was caused by poor survival of juveniles during the outbreak and subsequent poor recruitment of breeding females. These results suggest synergistic effects of 'bottom-up' and 'top-down' processes on host population dynamics.

Performance Differences in Male Youth Basketball Players According to Selection Status and Playing Position: An Evaluation of the Basketball Learning and Performance Assessment Instrument.

The Basketball Learning and Performance Assessment Instrument (BALPAI) has been initially developed and evaluated to assess the performance of students or youth basketball players on the entry level. As it is currently the only observational instrument that allows an overall assessment of players' in-game performance, it might represent a valuable tool for talent identification and development purposes. To investigate this potential field of application, this study aimed to evaluate the BALPAI regarding reliability and diagnostic validity when assessing youth basketball players within a competitive setting. The study sample comprised N = 54 male youth players (M age = 14.36 ± 0.33 years) of five regional selection teams (Point Guards, PG: n = 19; Shooting Guards and Small Forwards, SG/SF: n = 21; and Power Forwards and Centers, PF/C: n = 14) that competed at the annual U15 national selection tournament of the German Basketball Federation (n = 24 selected; n = 30 non-selected). A total of 1997 ball-bound actions from five games were evaluated with BALPAI. The inter-rater reliability was assessed for technical execution, decision making, and final efficacy. The diagnostic validity of the instrument was examined via mean group comparisons of the players' offensive game involvement and performance regarding both selection-dependent and position-dependent differences. The inter-rater reliability was confirmed for all performance-related components (κ adj ≥ 0.51) while diagnostic validity was established only for specific the BALPAI variables. The selection-dependent analysis demonstrated higher offensive game involvement of selected players in all categories (p < 0.05, 0.27 ≤ Φ ≤ 0.40) as well as better performance in shooting and receiving (p < 0.05, 0.23 ≤ Φ ≤ 0.24). Within the positional groups, the strongest effects were demonstrated among PG (p < 0.05, 0.46 ≤ Φ ≤ 0.60). The position-dependent analysis revealed that PG are more involved in total ball-bound actions (p < 0.05; 0.34 ≤ Φ ≤ 0.53), passing (p < 0.001; 0.55 ≤ Φ ≤ 0.67), and dribbling (p < 0.05, 0.45 ≤ Φ ≤ 0.69) compared to players in other positions. Further differences between players according to selection status and playing position were not detected. The results of this evaluation indicate that the instrument, in its current form, is not yet applicable in competitive youth basketball. The findings highlight the importance of optimizing BALPAI for reliable and valid performance assessments in this context. Future studies should investigate the application of stricter and position-specific criteria to use the observational tool for talent identification and development purposes.

The effectiveness of 3D multiple object tracking training on decision-making in soccer.

BACKGROUND: Soccer requires athletes to make quick decisions in dynamic environments. Several off-court technology-based interventions have been developed to train these perceptual cognitive skills. However, the evidence for training transfer using technologies to athletic performance has been sparse. Previous research found 3-dimensional multiple object tracking (3D MOT) training to cause a significant increase in quality of passing decision-making. Limitations to the research warrant further investigation of this association. PURPOSE: To re-examine the effectiveness of 3D MOT on training decision-making. METHODS: Thirty-one NCAA Division III soccer players (female n = 16) were randomized to 3D MOT training or a control task. The experimental group received 10 training sessions over a span of 4 weeks. RESULTS: The manipulation check indicated a significant training effect in 3D MOT performance for the intervention but not the control group (F(1,29) = 21.46, p < .001, np2 = .43). Non-significant changes with small effect sizes (np2 = .01-.03) in decision-making and measures of near-transfer were found. CONCLUSION: The findings challenge the association between 3D MOT training and increased quality of decision-making in soccer.

Patterns and consequences of age-linked change in local relatedness in animal societies.

The ultimate payoff of behaviours depends not only on their direct impact on an individual, but also on the impact on their relatives. Local relatedness-the average relatedness of an individual to their social environment-therefore has profound effects on social and life history evolution. Recent work has begun to show that local relatedness has the potential to change systematically over an individual's lifetime, a process called kinship dynamics. However, it is unclear how general these kinship dynamics are, whether they are predictable in real systems and their effects on behaviour and life history evolution. In this study, we combine modelling with data from real systems to explore the extent and impact of kinship dynamics. We use data from seven group-living mammals with diverse social and mating systems to demonstrate not only that kinship dynamics occur in animal systems, but also that the direction and magnitude of kinship dynamics can be accurately predicted using a simple model. We use a theoretical model to demonstrate that kinship dynamics can profoundly affect lifetime patterns of behaviour and can drive sex differences in helping and harming behaviour across the lifespan in social species. Taken together, this work demonstrates that kinship dynamics are likely to be a fundamental dimension of social evolution, especially when considering age-linked changes and sex differences in behaviour and life history.

Genetic variance in fitness indicates rapid contemporary adaptive evolution in wild animals.

The rate of adaptive evolution, the contribution of selection to genetic changes that increase mean fitness, is determined by the additive genetic variance in individual relative fitness. To date, there are few robust estimates of this parameter for natural populations, and it is therefore unclear whether adaptive evolution can play a meaningful role in short-term population dynamics. We developed and applied quantitative genetic methods to long-term datasets from 19 wild bird and mammal populations and found that, while estimates vary between populations, additive genetic variance in relative fitness is often substantial and, on average, twice that of previous estimates. We show that these rates of contemporary adaptive evolution can affect population dynamics and hence that natural selection has the potential to partly mitigate effects of current environmental change.

Decision-Making Skills in Youth Basketball Players: Diagnostic and External Validation of a Video-Based Assessment.

Decision-making is a central skill of basketball players intending to excel individually and contribute to their teams' success. The assessment of such skills is particularly challenging in complex team sports. To address this challenge, this study aimed to conceptualize a reliable and valid video-based decision-making assessment in youth basketball. The study sample comprised youth basketball players of the German U16 national team (n = 17; MAge = 16.01 ± 0.25 years) and students of a sports class (n = 17; MAge = 15.73 ± 0.35 years). Diagnostic validity was tested by determination of the performance levels according to response accuracy as well as response time in the assessment. External validity was examined by investigation of the correlation between the diagnostic results of the elite athletes and their real game performance data associated with passing skills. Logistic regression analysis revealed that the diagnostic results discriminate between performance levels (χ2(2) = 20.39, p < 0.001, Nagelkerke's R2 = 0.60). Multiple regression analysis demonstrated a positive relationship between the diagnostic results and assists (F(2,10) = 4.82, p < 0.05; R2 = 0.49) as well as turnovers per game (F(2,10) = 5.23, p < 0.05; R2 = 0.51). However, no relationship was detected regarding the assist-turnover ratio. Further, response time discriminated within the elite athletes' performance data but not between performance levels while for response accuracy the opposite is the case. The results confirm the diagnostic and external validity of the assessment and indicate its applicability to investigate decision-making skills in youth basketball.

Perceptual-Motor and Perceptual-Cognitive Skill Acquisition in Soccer: A Systematic Review on the Influence of Practice Design and Coaching Behavior.

Facilitating players' skill acquisition is a major challenge within sport coaches' work which should be supported by evidence-based recommendations outlining the most effective practice and coaching methods. This systematic review aimed at accumulating empirical knowledge on the influence of practice design and coaching behavior on perceptual-motor and perceptual-cognitive skill acquisition in soccer. A systematic search was carried out according to the PRISMA guidelines across the databases SPORTDiscus, PsycInfo, MEDLINE, and Web of Science to identify soccer-specific intervention studies conducted in applied experimental settings (search date: 22nd November 2020). The systematic search yielded 8,295 distinct hits which underwent an independent screening process. Finally, 34 eligible articles, comprising of 35 individual studies, were identified and reviewed regarding their theoretical frameworks, methodological approaches and quality, as well as the interventions' effectiveness. These studies were classified into the following two groups: Eighteen studies investigated the theory-driven instructional approaches Differential Learning, Teaching Games for Understanding, and Non-linear Pedagogy. Another seventeen studies, most of them not grounded within a theoretical framework, examined specific aspects of practice task design or coaches' instructions. The Downs and Black checklist and the Template for Intervention Description and Replication were applied to assess the quality in reporting, risk of bias, and the quality of interventions' description. Based on these assessments, the included research was of moderate quality, however, with large differences across individual studies. The quantitative synthesis of results revealed empirical support for the effectiveness of coaching methodologies aiming at encouraging players' self-exploration within representative scenarios to promote technical and tactical skills. Nevertheless, "traditional" repetition-based approaches also achieved improvements with respect to players' technical outcomes, yet, their impact on match-play performance remains widely unexplored. In the light of the large methodological heterogeneity of the included studies (e.g., outcomes or control groups' practice activities), the presented results need to be interpreted by taking the respective intervention characteristics into account. Overall, the current evidence needs to be extended by theory-driven, high-quality studies within controlled experimental designs to allow more consolidated and evidence-based recommendations for coaches' work.