Talent identification and selection in soccer is typically based on subjective evaluations of experienced coaches. Recently, there has been a trend to complement these subjective assessments with objective tests. However, there is currently no comprehensive overview of the prognostic relevance of objective measurements in youth soccer. Therefore, the primary purpose of the current study was to systematically review published empirical studies related to the prognostic relevance of physiological (e.g. endurance and speed) and physical characteristics (i.e. height and weight). Of 6876 initially identified studies, nine articles were included. In those studies, endurance (nine studies), change of direction (seven), height (seven), and weight (seven) received the most meaningful consideration within the literature. In regard to physiological predictors, between 16 and 29 effect sizes were tested for endurance, sprint, and change of direction, and about half of them were found to be significant with small to moderate effects (0.37 ≤ Mdn(d) ≤ 0.57). In addition, while only investigated in two studies all tested effect sizes for repeated sprint ability were found to be significant. Despite their frequent consideration in the literature, low numbers of significant effect sizes (≤ 26%) and magnitude (0.23 ≤ Mdn(d) ≤ 0.29) were found for the physical predictors height and weight. Overall, results appear to be dependent on the respective study design and, in particular, moderator variables (i.e. soccer development stage, performance level T1/T2, prognostic period, and sample size). Consequently, additional research seems warranted to more comprehensively investigate the predictive relevance of the individual characteristics using more homogeneous study designs.
Within the multidimensional nature of soccer talent, recently there has been an increasing interest in psychological characteristics. The aim of this present research was to systematically review the predictive value of psychological talent predictors and provide better comprehension of the researchers’ methodological approaches and the empirical evidence for individual factors (i.e., psychomotor, perceptual-cognitive and personality-related). Results highlighted heterogeneous study designs (e.g., participants, measurement methods, statistical analyses) which may limit the comparability of studies’ findings. Analyzing the number of included studies, psychomotor (n = 10) and personality-related factors (n = 8) received more consideration within the literature than perceptual-cognitive factors (n = 4). In regard to empirical evidence, dribbling (0.47 ≤ d ≤ 1.24), ball control (0.57 ≤ d ≤ 1.28) and decision-making (d = 0.81) demonstrated good predictive values as well as the achievement motives hope for success (0.27 ≤ d ≤ 0.74) and fear of failure (0.21 ≤ d ≤ 0.30). In conclusion, there is growing acceptance of the need for more complex statistical analyses to predict future superior performance based on measures of current talent. New research addresses the necessity for large-scale studies that employ multidisciplinary test batteries to assess youth athletes at different age groups prospectively.
Objectives This study aimed to develop a valid video-based diagnostic instrument that assesses decision-making with a sport-specific motor response. Methods A total of 86 German youth academy players (16.7 ± 0.9 years) viewed game situations projected on a large video screen and were required to make a decision by dribbling and passing to one of three targets (representing different decision options). The test included 48 clips separated into two categories: build-up (bu) and offensive decisions (off). Criterion-related validity was tested based on age (i.e., U16, U17, and U19), playing status (i.e., minutes played in official matches of the current season) and in a prospective approach relating to future youth national team status (i.e., selected or nonselected). Finally, it was investigated whether decision-making competence was influenced by playing position (i.e., defenders vs. midfielders vs. forwards). Results Instrumental reliability demonstrated satisfactory values for SCbu (r = 0.72), and lower for SCoff (r = 0.56). Results showed the diagnostic instrument is suitable for discriminating between playing status (SCbu: Φ = 0.22, p < 0.01; SCoff: Φ = 0.14, p < 0.05) and between younger (U16) and older players (U17 > U16 in SCbu: Φ = 0.24 and SCoff: Φ = 0.39, p < 0.01; U19 > U16 in SCbu: Φ = 0.41 and SCoff: Φ = 0.46, p < 0.01); however, there was no difference between U17 and U19 players. Furthermore, the predictive value of the test indicates that future youth national team players make better decisions with respect to the build-up category (SCbu: Φ = 0.20; p < 0.05), whereas playing position did not significantly influence decision-making competence. Conclusion Results indicate the video-based decision-making diagnostic instrument can discriminate decision-making competence within a high-performance youth group. The outcomes associated with national youth team participation demonstrate the predictive value of the diagnostic instrument. This study provides initial evidence to suggest a new video-based diagnostic instrument with a soccer-specific motor response can be used within a talent identification process to assist with assessment of decision-making performance.
Recent studies have provided empirical evidence on the prognostic relevance of objective performance diagnostics in the soccer talent identification and development process. However, little is known about the prognostic validity of coaches' subjective evaluations of performance. This study evaluated objective and subjective assessments within a nationwide talent development program and addressed motor, perceptual skill, and personality-related performance factors. Male players (N = 13,869; Mage = 12.59 ± 1.07 years) from the age groups U12 to U15 of the German soccer talent development program participated in this study. Participants completed an objective motor diagnostic (sprint, agility, dribbling, ball control, juggling) and were subjectively rated by their coaches (kicking skills, endurance, individual tactical skills, psychosocial skills). All nine predictors were assessed with sufficient psychometric properties (α ≥ 0.72; except dribbling and ball control: α ≥ 0.53). Players' success three seasons later was operationalized by achieving professional youth academy level or not (success rate, 9%). Independent-samples t-tests analyzed univariate mean group comparisons between future selected and non-selected players. Logistic regression models examined the multivariate prognostic validity of all assessments by predicting success with subjective (model 1), objective (model 2), and both groups of predictors (model 3). Confirming the univariate prognostic validity, future selected outperformed non-selected players regarding all predictors (each p < 0.001, except for agility in U15: p < 0.01). Tactical skills, kicking skills, and sprint were of highest predictive value (d ≥ 0.61 in each age group). Multivariate results provided empirical evidence for the subjective (7% ≤ Nagelkerke's R2 ≤ 11%; each p < 0.001) and objective (8% ≤ Nagelkerke's R2 ≤ 13%; each p < 0.001) assessments' prognostic validity. However, model 3 revealed the best statistical explanatory power in each age group (0.15 ≤ Nagelkerke's R2 ≤ 0.20; p < 0.001). In this combined assessment model, sprint, tactical skills, and dribbling were found to be the most predictive variables. In conclusion, this study reinforces the call for multidimensional diagnostics integrating objective and subjective assessments. Future research is needed to address the demands for longitudinal analyses of subjective ratings, the integration of biological maturation, and empirical evidence for female soccer.
The influence of biological maturity status (BMS) on talent identification and development within elite youth soccer is critically debated. During adolescence, maturity-related performance differences within the same age group may cause greater chances of being selected for early maturing players. Therefore, coaches need to consider players' BMS. While standard methods for assessing BMS in adolescents are expensive and time-consuming imaging techniques (i.e., X-ray and MRI), there also exist more pragmatic procedures. This study aimed to evaluate commonly used methods to assess BMS within a highly selected sample of youth soccer players. A total of N = 63 elite male soccer players (U12 and U14) within the German Soccer Association's talent promotion program completed a test battery assessing BMS outcomes. Utilizing MRI diagnostics, players' skeletal age (SAMRI) was determined by radiologists and served as the reference method. Further commonly used methods included skeletal age measured by an ultrasound device (SAUS), the maturity offset (MOMIR), and the percentage of adult height (PAHKR). The relation of these alternative BMS outcomes to SAMRI was examined using different perspectives: performing bivariate correlation analyses (1), modeling BMS as a latent variable (BMSlat) based on the multiple alternative diagnostics (2), and investigating individual differences in agreement (3). (1) Correlations of SAMRI and the further BMS variables ranked from r = 0.80 to r = 0.84 for the total sample and were lower for U12 (0.56 ≤ r ≤ 0.66), and U14 (0.61 ≤ r ≤ 0.74) (2). The latent structural equation modeling (SEM) (R2 = 51%) revealed a significant influence on BMSlat for MOMIR (β = 0.51, p <0.05). The additional contribution of PAHKR (β = 0.27, p = 0.06) and SAUS (β = −0.03, p = 0.90) was rather small (3). The investigation of individual differences between the reference method and alternative diagnostics indicated a significant bias for MOMIR (p <0.01). The results support the use of economical and time-efficient methods for assessing BMS within elite youth soccer. Bivariate correlation analyses as well as the multivariate latent variable approach highlight the measures' usefulness. However, the observed individual level differences for some of the utilized procedures led to the recommendation for practitioners to use at least two alternative assessment methods in order to receive more reliable information about players' BMS within the talent promotion process.
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