Quantifying the Extent to Which Junior Performance Predicts Senior Performance in Olympic Sports: A Systematic Review and Meta-analysis.

BACKGROUND: To what extent does junior athletic performance predict senior athletic performance (i.e., in the highest, open-age category)? This question is the subject of a lively debate in the literature. Following traditional theories of giftedness and expertise, some researchers and practitioners have proposed that a high level of junior performance is a prerequisite for the development of a high level of later senior performance. Sceptics of this view hold that junior performance has limited predictive value for later senior performance, pointing to empirical evidence indicating that predictors (e.g., participation patterns) of junior performance and of senior performance differ. The straightforward way to resolve this controversy empirically is to test the correlation between junior and senior performance. OBJECTIVE: To provide robust and generalizable evidence on this issue, we performed a systematic review and meta-analysis of relevant studies. The aim was to quantify the overall correlation between junior and senior performance and then test whether correlations vary across junior age categories and subsamples (e.g., types of sports). METHODS: A systematic literature search was conducted in SPORTDiscus, Eric, ProQuest, PsychInfo, PubMed, Scopus, WorldCat, and Google Scholar from 27 January through 30 April 2022. We searched for original studies that recorded athletes' junior and senior performance longitudinally and included measures of association between junior and senior performance. Quality of evidence was evaluated using the Mixed Methods Appraisal Tool version for nonrandomized studies. RESULTS: The search yielded k = 129 effect sizes from N = 13,392 athletes from a wide range of Olympic sports, 62% male and 38% female, from 2006 to 2021. Four central findings emerged: (1) Overall, the meta-analytic pooled correlation between junior and senior performance was [Formula: see text] = 0.148. That is, junior performance explained only 2.2% of the reliable variance in senior performance. (2) The finding was robust across types of sports, sexes, wider or narrower performance ranges, national or international samples, and binary or continuous performance measures. (3) Effects varied across junior age categories: the younger the junior age category, the lower the correlation between junior and senior performance, with [Formula: see text] ranging from [Formula: see text] = - 0.052 to [Formula: see text] = 0.215. That is, across junior age categories, junior performance explained 0-4.6% of the reliable variance in senior performance. (4) The quality of primary studies was high. DISCUSSION: The results suggest that junior performance has very little, if any, predictive value for senior performance. The findings run counter to claims from traditional theories of both giftedness and expertise. From an applied perspective, talent selection typically begins around puberty or younger-age ranges where youth performance is uncorrelated or negatively correlated with later senior performance. The evidence presented here raises serious questions about the use of junior performance for talent selection purposes. A PRISMA-P protocol was registered at https://osf.io/gck4a/ .

Effects of Early Talent Promotion on Junior and Senior Performance: A Systematic Review and Meta-Analysis.

BACKGROUND: Does younger involvement in talent promotion programs (TPPs) facilitate the attainment of higher performance levels? This question is the subject of the present meta-analysis. Many national sport systems have established TPPs such as federations' junior squads (including under-age selection teams) and youth sport academies, and many are making expanding investments in TPPs. TPPs seek to select the most advanced youth high performers at young ages, around puberty or younger, and then strive to further accelerate their performance development. However, studies show 25-55% annual athlete turnover within TPPs. In this context, accelerated biological maturation (puberty, growth spurt), high relative age within one's birth year, and intensified sport-specific childhood/adolescent practice may boost rapid junior performance, but the effects diminish or are reversed by adulthood. Moreover, expanded opportunity costs and risks (time demands, injury, burnout) imposed on young TPP participants may impair their long-term development and even prematurely terminate their career. OBJECTIVE: We aimed to provide robust and generalizable evidence on the effects of early talent promotion on junior and senior performance through a systematic review and meta-analysis. METHODS: A systematic literature search was conducted 18/03-03/04/2023 in SPORTDiscus, ProQuest, PsycINFO, PubMed, Scopus, WorldCat, and Google Scholar. We searched for original studies that compared athletes across defined higher and lower performance levels within defined types of sports, age categories, and sexes, regarding their age at commencement of TPP involvement and reported effect sizes or data needed to compute effects sizes. Mean meta-analytic Cohen's d ¯ was computed separately for junior and senior athletes. Quality of evidence was evaluated using the mixed-methods appraisal tool. RESULTS: The search yielded k = 51 effect sizes from N = 6233 athletes from a wide range of countries and sports, 82% male and 18% female, from 2009 to 2022. The central finding is that effects on short-term junior performance versus long-term senior performance are opposite, whereby higher-performing junior athletes began TPP involvement at younger ages than lower-performing junior athletes, d ¯ = - 0.53. In contrast, higher-performing senior athletes began TPP involvement at older ages than lower-performing senior athletes, d ¯ = 0.56. The findings are robust across different TPPs (federation's junior squad/selection team, youth academy), individual and team sports, and performance levels compared (international, national, regional). The quality of primary studies was high. DISCUSSION: The findings are consistent with recent meta-analytic evidence that participation patterns predicting early junior success versus long-term senior success are opposite (starting age, main-sport and other-sports practice amounts, age to reach performance 'milestones'). We discuss theoretical and practical implications of potential selection and 'treatment' effects of TPPs. CONCLUSIONS: Consistent across different populations, early TPP involvement is positively correlated with short-term junior performance but is negatively correlated with long-term senior performance.

Participation patterns in talent development in youth sports.

There has been a longstanding debate about the question: What amounts of what types of youth sport activities optimally facilitate later athletic excellence? This article provides a review of relevant research. We first evaluate popular conceptualizations of participation patterns-early specialization, deliberate practice, and deliberate play. Then, we review the available evidence on associations between performance and individual participation variables. The review reveals conceptual, definitional, and empirical flaws of the conceptions of early specialization, deliberate practice, and deliberate play. These approaches thus possess limited usefulness for empirical research. A review of studies considering individual, clearly defined participation variables provides a differentiated pattern of findings: Predictors of rapid junior performance and of long-term senior performance are opposite. Higher-performing juniors, compared to lower-performing peers, started playing their main sport, began involvement in talent promotion programs, and reached developmental performance milestones at younger ages, while accumulating larger amounts of coach-led main-sport practice, but less other-sports practice. In contrast, senior world-class athletes, compared to less-accomplished national-class peers, started playing their main sport, began involvement in talent promotion programs, and achieved performance milestones at older ages, while accumulating less coach-led main-sport practice, but more other-sports practice. We discuss implications for theory, practice, and future research.

Quantifying the Extent to Which Successful Juniors and Successful Seniors are Two Disparate Populations: A Systematic Review and Synthesis of Findings.

BACKGROUND: To what extent does the pathway to senior elite success build on junior elite success? Evidence from longitudinal studies investigating athletes' junior-to-senior performance development is mixed; prospective studies have reported percentages of juniors who achieved an equivalent competition level at senior age (e.g., international championships at both times) ranging from 0 to 68%. Likewise, retrospective studies have reported percentages of senior athletes who had achieved an equivalent competition level at junior age ranging from 2 to 100%. However, samples have been heterogeneous in terms of junior age categories, competition levels, sex, sports, and sample sizes. OBJECTIVE: This study aimed to establish more robust and generalizable findings via a systematic review and synthesis of findings. We considered three competition levels-competing at a national championship level, competing at an international championship level, and winning international medals-and addressed three questions: (1) How many junior athletes reach an equivalent competition level when they are senior athletes? (2) How many senior athletes reached an equivalent competition level when they were junior athletes? The answers to these questions provide an answer to Question (3): To what extent are successful juniors and successful seniors one identical population or two disparate populations? METHODS: We conducted a systematic literature search in SPORTDiscus, ERIC, ProQuest, PsychInfo, PubMed, Scopus, WorldCat, and Google Scholar until 15 March 2022. Percentages of juniors who achieved an equivalent competition level at senior age (prospective studies) and of senior athletes who had achieved an equivalent competition level at junior age (retrospective studies) were aggregated across studies to establish these percentages for all athletes, separately for prospective and retrospective studies, junior age categories, and competition levels. Quality of evidence was evaluated using the Mixed Methods Appraisal Tool (MMAT) version for descriptive quantitative studies. RESULTS: Prospective studies included 110 samples with 38,383 junior athletes. Retrospective studies included 79 samples with 22,961 senior athletes. The following findings emerged: (1) Few elite juniors later achieved an equivalent competition level at senior age, and few elite seniors had previously achieved an equivalent competition level at junior age. For example, 89.2% of international-level U17/18 juniors failed to reach international level as seniors and 82.0% of international-level seniors had not reached international level as U17/18 juniors. (2) Successful juniors and successful seniors are largely two disparate populations. For example, international-level U17/18 juniors and international-level seniors were 7.2% identical and 92.8% disparate. (3) Percentages of athletes achieving equivalent junior and senior competition levels were the smallest among the highest competition levels and the youngest junior age categories. (4) The quality of evidence was generally high. DISCUSSION: The findings question the tenets of traditional theories of giftedness and expertise as well as current practices of talent selection and talent promotion. A PRISMA-P protocol was registered at https://osf.io/gck4a/ .

In-season head-coach changes have positive short- and long-term effects on team perfor-mance in men's soccer-evidence from the Premier League, Bundesliga, and La Liga.

The study investigated effects of in-season head-coach changes (HCC) on the subsequent team performance in men's English, German, and Spanish premier soccer leagues. A pre-post matched-controls design involved 149 HCC-teams and 3,960 games in 2010-19. Analyses (paired t-test, repeated-measurement ANOVA) revealed five central findings. 1. An HCC was preceded by a spell of under-performance, with a particular performance collapse in the two last pre-HCC rounds. 2. Performance showed an instant, strong improvement in the first post-HCC game. 3. The performance remained increased up to 16 post-HCC rounds. 4. Post-HCC performance also exceeded teams' initial baseline performance earlier before the HCC. Accordingly, the summed performance through 8, 12, and 16 post-HCC rounds exceeded the performance through 8, 12, and 16 pre-HCC rounds (0.92 < Cohen's d < 1.17). 5. HCC-teams' pre-post performance development differed from matched non-HCC control teams. In sum, the present evidence suggests positive short, medium, and long-term HCC effects at the highest professional soccer level. Theoretical hypotheses discussed in the literature - the "common-sense," "ritual-scapegoating," "vicious-circle," and "mean-reversion" hypotheses - are partly inconsistent with the present evidence. However, the evidence is fully consistent with a new hypothesis introduced here: the hypothesis of relief from a coach's performance-suppressing factor (RCPSF).

Predictors of Junior Versus Senior Elite Performance are Opposite: A Systematic Review and Meta-Analysis of Participation Patterns.

BACKGROUND: Does early specialization facilitate later athletic excellence, or is early diversification better? This is a longstanding theoretical controversy in sports science and medicine. Evidence from studies investigating athletes' starting age, childhood/adolescent progress, and amounts of coach-led practice and peer-led play in their main sport and in other sports has been mixed. Each participation variable was positively correlated with performance in some studies but uncorrelated or negatively correlated with performance in others. However, samples were heterogeneous in age, sports, and performance levels. OBJECTIVE: This study aimed to establish robust, generalizable findings through a systematic review and meta-analysis. We investigated three questions: (1) did higher- and lower-performing athletes differ in childhood/adolescent progress, starting age, or amounts of main-sport or other-sports practice or play; (2) do effects differ between junior and adult athletes, compared performance levels, or types of sports; and (3) are effect sizes from different predictors associated with one another? METHODS: We conducted a systematic literature search in SPORTDiscus, ERIC, ProQuest, PsycINFO, PubMed, Scopus, WorldCat, and Google Scholar until 28 February 2021. Selection criteria included original research studies comparing higher- versus lower-performing athletes regarding one or more of our predictor variables within defined age categories, sports, and sex, and reporting effect sizes or data needed to compute effects sizes. Mean meta-analytic Cohen's d was calculated for each predictor. Quality of evidence was evaluated using GRADE. RESULTS: In total, 71 study reports met all eligibility criteria and included 262 international athlete samples, 685 effect sizes, and a total sample size of 9241 athletes from local to Olympic competition level and from diverse sports. The following findings emerged. (1) Compared with their national-class counterparts, adult world-class athletes had more childhood/adolescent multi-sport coach-led practice, a later main-sport start, less main-sport practice, and slower initial progress (|0.23|< [Formula: see text]<|0.50|; all p < 0.001). (2) The opposite was true for predictors of junior-age performance: higher-performing juniors had an earlier main-sport start, more main-sport practice, less other-sports practice, and faster initial progress (|0.23|< [Formula: see text]< |0.61|; all p < 0.001). (3) Main-sport or other-sports peer-led play had negligible effects (all p > 0.05). (4) Results were robust across types of sports. (5) Effect sizes from different predictors were associated with one another (|0.64|< r <|0.79|). A GRADE assessment revealed a low quality of evidence for peer-led play but a moderate to high quality of evidence for all other predictors. DISCUSSION: Excess childhood/adolescent specialized practice may hinder athletes' long-term development through overuse injury, burnout, suboptimal athlete-sport match, and limiting long-term learning capital. By contrast, adult world-class athletes' childhood/adolescent multi-sport practice with reduced main-sport practice implied a relatively resource-preserving, cost-reducing, and risk-buffering pattern that yielded greater long-term sustainability and practice efficiency.

What Makes a Champion? Early Multidisciplinary Practice, Not Early Specialization, Predicts World-Class Performance.

What explains the acquisition of exceptional human performance? Does a focus on intensive specialized practice facilitate excellence, or is a multidisciplinary practice background better? We investigated this question in sports. Our meta-analysis involved 51 international study reports with 477 effect sizes from 6,096 athletes, including 772 of the world's top performers. Predictor variables included starting age, age of reaching defined performance milestones, and amounts of coach-led practice and youth-led play (e.g., pickup games) in the athlete's respective main sport and in other sports. Analyses revealed that (a) adult world-class athletes engaged in more childhood/adolescent multisport practice, started their main sport later, accumulated less main-sport practice, and initially progressed more slowly than did national-class athletes; (b) higher performing youth athletes started playing their main sport earlier, engaged in more main-sport practice but less other-sports practice, and had faster initial progress than did lower performing youth athletes; and (c) youth-led play in any sport had negligible effects on both youth and adult performance. We illustrate parallels from science: Nobel laureates had multidisciplinary study/working experience and slower early progress than did national-level award winners. The findings suggest that variable, multidisciplinary practice experiences are associated with gradual initial discipline-specific progress but greater sustainability of long-term development of excellence.

Age of Early Specialization, Competitive Volume, Injury, and Sleep Habits in Youth Sport: A Preliminary Study of US Youth Basketball.

BACKGROUND: Concerns for youth sports in the United States often focus on early sport specialization, overemphasis on competition, injuries, and burnout. Little research has addressed relationships among the preceding and other concerns, including time away from organized sport, sleep, and perceptions of physical and psychological well-being. HYPOTHESIS: There is an association between reported competitive gameplay volume and specialization, injury, and fatigue among elite youth basketball players. STUDY DESIGN: Cross-sectional study; convenience sample. LEVEL OF EVIDENCE: Level 4. METHODS: An anonymous questionnaire was administered to a convenience sample of youth basketball players between 13 and 18 years of age from across the United States. Participants were queried about multiple factors, including the extent of their participation in organized basketball and other sports, time away from organized basketball, injury, sleep, and feelings of exhaustion related to basketball participation. RESULTS: A total of 772 participants (145 girls, 627 boys) completed a survey. All participants played for a select or elite club basketball team and/or a high school basketball team. Overall, 49% played more than 50 games within the past year. A total of 73% were specialized in basketball, 58% prior to age 14 years, and 35% prior to age 11 years. In all, 70% reported less than 1 month away from organized basketball within the past year, and 28% reported no time away. A total of 54% reported sleeping less than the recommended 8 hours each night during the school year. Within the prior year, 55% reported feeling physically exhausted and 45% reported feeling mentally exhausted from basketball. Regression analysis did not find any significant relationships between early specialization prior to age 14 years and basketball-related injury or feelings of mental or physical exhaustion. CONCLUSION: In this select group of youth basketball players, the majority specialized in basketball prior to age 14 years and reported a large number of competitive events with little time away from organized basketball. CLINICAL RELEVANCE: The results from a sample of highly competitive youth basketball players indicate issues that warrant further attention and research regarding the potential impact of specialization, frequent competitions, lack of time away from organized sport, and perceptions of well-being in young athletes.

Non-linear association of efficiency of practice of adult elite athletes with their youth multi-sport practice.

We explored associations of elite athletes' multi-year efficiency of practice and improvement of performance with their current and earlier participation patterns. Participants were 80 adult German track-and-field national-squad athletes. Performance improvement was measured as development of athletes' highest track-and-field championship level and placing from 19 to 25 years (t1-t2). Practice efficiency was defined as performance improvement per amount of coach-led athletics practice from t1 to t2. Participation variables included amounts of coach-led practice and peer-led play in athletics and other sports through t1 and t1-t2. Analyses involved an advanced machine learning procedure, XGBoost, allowing non-linear, multivariate exploration. We computed two models, one for performance improvement ("good" discriminative performance, AUC = 0.82) and one for practice efficiency ("fair", AUC = 0.73). Four central findings emerged: 1. Childhood/adolescent coach-led multi-sport practice was a critical discriminator of adult practice efficiency and performance improvement. 2. Associations were non-linear, displaying a saturation pattern. 3. The likelihood of achieving high adult practice efficiency was greatest when combining ~1,000-2,500 track-and-field practice hours until t1 with ~1,250 other-sports practice hours until t1. 4. Peer-led engagement in any sport had negligible effects. Childhood/adolescent multi-sport coach-led practice apparently facilitated long-term sustainability of athletes' development of adult practice efficiency and performance improvement in athletics.

Retirement of professional soccer players - A systematic review from social sciences perspectives.

Retiring professional athletes face multifaceted changes and potential issues of adjustment, occupational development, and well-being, which raises concerns around the world. The study systematically reviewed the available research investigating professional soccer players' sport retirement from social sciences perspectives. The literature search in electronic databases and a "snowballing" procedure yielded 17 eligible studies investigating > 2,200 retired professional soccer players. The review followed the PRISMA statement. Nine studies focused on an early transition phase to retirement period; four studies investigated later periods of ten years or longer after retirement. Around half of the players reported involuntary retirement, often associated with declining performance and/or injury. Studies suggest issues of adjustment and mental health during early years after retirement, while psychological issues had apparently declined around 1-2 decades after retirement. However, available studies had notable limitations including lack of evidenced representative samples, report of measures' reliability, and control for confounders. Furthermore, while theoretical models emphasise a holistic perspective, quantitative research often took a narrow rather than holistic perspective. In summary, available knowledge is fraught with some uncertainty regarding reliability and representativeness of the population of retired professional soccer players. We offer future directions to advance the development of a theory of sport retirement.

Correction: The path to international medals: A supervised machine learning approach to explore the impact of coach-led sport-specific and non-specific practice.

[This corrects the article DOI: 10.1371/journal.pone.0239378.].

The path to international medals: A supervised machine learning approach to explore the impact of coach-led sport-specific and non-specific practice.

Research investigating the nature and scope of developmental participation patterns leading to international senior-level success is mainly explorative up to date. One of the criticisms of earlier research was its typical multiple testing for many individual participation variables using bivariate, linear analyses. Here, we applied state-of-the-art supervised machine learning to investigate potential non-linear and multivariate effects of coach-led practice in the athlete's respective main sport and in other sports on the achievement of international medals. Participants were matched pairs (sport, sex, age) of adult international medallists and non-medallists (n = 166). Comparison of several non-ensemble and tree-based ensemble binary classification algorithms identified "eXtreme gradient boosting" as the best-performing algorithm for our classification problem. The model showed fair discrimination power between the international medallists and non-medallists. The results indicate that coach-led other-sports practice until age 14 years was the most important feature. Furthermore, both main-sport and other-sports practice were non-linearly related to international success. The amount of main-sport practice displayed a parabolic pattern while the amount of other-sports practice displayed a saturation pattern. The findings question excess involvement in specialised coach-led main-sport practice at an early age and call for childhood/adolescent engagement in coach-led practice in various sports. In data analyses, combining traditional statistics with advanced supervised machine learning may improve both testing of the robustness of findings and new discovery of patterns among multivariate relationships of variables, and thereby of new hypotheses.

Childhood practice and play as determinants of adolescent intrinsic and extrinsic motivation among elite youth athletes.

The study empirically tested the postulate of the Developmental Model of Sport Participation (DMSP; Côté, J., Baker, J., & Abernethy, B. (2007). Practice and play in the development of sport expertise. In R. Eklund & G. Tenenbaum (Eds.), Handbook of sport psychology (pp. 184-202). Hoboken, NJ: Wiley) that diversified childhood self-led sport play will beneficially affect future, adolescent intrinsic motivation. Participants were 178 elite youth athletes (age 15.3 ± 1.5 years) from several game and non-game sports; 117 were members of the federal state or national junior squad in their respective sport. A questionnaire measured current (adolescent) intrinsic and extrinsic motivation of the youth athletes using the Sport Motivation Scale (Pelletier, L. G., Fortier, M. S., Vallerand, R. J., Tuson, K. M., Brière, N. M., & Blais, M. R. (1995). Towards a new measure of intrinsic motivation, extrinsic motivation, and amotivation in sports: The sport motivation scale (SMS). Journal of Sport & Exercise Psychology, 17, 35-53) and their earlier volume of childhood engagement (through 12 years) in coach-led practice and self-led play in their respective main sport and other sports. Analyses revealed that adolescent intrinsic motivation was not significantly correlated with earlier childhood self-led sport activities, self-led play in particular, or childhood sports diversification. Furthermore, considering all different types of childhood sport activities together in multiple regression analyses, they did not provide meaningful explanatory power regarding adolescent intrinsic or extrinsic motivation. In summary, the results did not provide support for the postulate of the DMSP among elite youth athletes. The findings suggest that future research may seek to enable more robust empirical substantiation of the DMSP postulate.

"Macro-structure" of developmental participation histories and "micro-structure" of practice of German female world-class and national-class football players.

The study examined the "micro-structure" of football practice and the "macro-structure" of participation history of female professional football players. Participants were 29 German 1st league (Bundesliga) players, 14 of whom played on the senior national team (Olympic Champion in 2016). A questionnaire recorded the players' positions, proportions of physical conditioning, drill-type skill exercises and playing forms within coach-led football practice, and the volume of coach-led practice and peer-led play, in both football and other sports, from childhood to adulthood. Analyses revealed that most athletes played various attacker and defender positions during development. National team players differed from their Bundesliga peers by less physical conditioning and greater proportions of playing forms within football practice. National team players also accumulated less total football practice until age 18 years, but more peer-led football and coach-led practice in other sports compared to their Bundesliga counterparts. Based on these variables, a binary logistic regression classified 93% of the national team and Bundesliga players correctly. Conclusion: A combination of long-term coach-led football practice involving a relatively large proportion of playing forms with considerable childhood/adolescent peer-led football play and coach-led practice in other sports may have facilitated adult performance among German female world-class football players.

The NBA and Youth Basketball: Recommendations for Promoting a Healthy and Positive Experience.

Participation in sports offers both short-term and long-term physical and psychosocial benefits for children and adolescents. However, an overemphasis on competitive success in youth sports may limit the benefits of participation, and could increase the risk of injury, burnout, and disengagement from physical activity. The National Basketball Association and USA Basketball recently assembled a group of leading experts to share their applied research and practices to address these issues. This review includes the group's analysis of the existing body of research regarding youth sports participation and the related health, performance, and psychosocial outcomes. Based upon this, age-specific recommendations for basketball participation are provided that aim to promote a healthy and positive experience for youth basketball players.

Sport-specific and non-specific practice of strong and weak responders in junior and senior elite athletics - A matched-pairs analysis.

Elite track and field athletes with greater and lesser multi-year performance improvement were compared regarding their developmental sport-specific and non-specific, organised (coach-led) and non-organised (peer-led) sporting activities. Athlete pairs were matched on gender, discipline and baseline performance in competitions (at 13/19 years). Their unequal subsequent performance development during junior (13-17 years; n = 138) and senior (19-23+ years; n = 80) age ranges defined "strong responders" and "weak responders". Analyses revealed that junior-age strong responders accumulated more organised practice in athletics than weak responders, while the amounts of all other types of activities were indifferent. Senior-age strong responders did not accumulate a greater total sum of all kinds of sport activities or greater amounts of organised practice in athletics or non-organised involvement in athletics or other sports than weak responders. But they engaged in more organised practice and competitions in other sports over more years (9 vs. 2 years) and specialised in athletics at a later age than weak responders (16 vs. 11 years). The results were also robust among senior international medallists vs. national medallists. The findings are reflected relative to the hypotheses of "multiple sampling and functional matching", "learning transfer as preparation for future learning" and "authenticity of variable learning experiences".