The importance of considering information related to athletes’ biological maturation within talent identification and development processes is frequently emphasized by both sport scientists and practitioners. Although there is evidence for the use of objective diagnostics for assessing biological maturation, little is known about its subjective determinations by coaches. Such approaches are particularly relevant when scientific support is limited. Therefore, the current study aimed to compare a practical subjective approach (coaches’ eye) to assess biological maturity timing (BMT) with objective reference diagnostics (MRI). For this purpose, data were collected from 63 male elite soccer players of the U12 and U14 age group who were part of the German talent promotion program. Players’ BMT (i.e., skeletal – chronological age) was assessed by MRI and a subjective rating of two coaches. Data analyses revealed high-rank correlations (rs = .55; p
Long-term sports participation and performance development are major issues in popular sports and talent development programs. This study aimed to provide longitudinal trends in youth female long jump performance development, participation, and relative age effects (RAEs), as longitudinal data for female athletes are missing. 51′894 season’s best results of female long jump athletes (n = 16′189) were acquired from the Swiss Athletics online database and analyzed within a range of 6–22 years of age. To examine longitudinal performance development and RAEs, data from athletes who participated in at least three seasons were selected (n = 41′253) and analyzed. Performance development was analyzed using age groups (AGs) and exact chronological age (CA) at competition. Differences between performances of birth quarters were analyzed using 83% confidence intervals (CIs) and smallest worthwhile change. Odds ratios (ORs) with 95% CI were used to quantify RAEs. With the traditional classification into age groups (AG), performances of athletes born between January and March (Q1) were significantly better than those born between October and December (Q4) from U8 to U17. Using exact CA resulted in similar performances in Q1 and Q4 until the U20 age category. The peak of participation was reached in the U12 category, and then decreased until the U23 category with a substantial drop at U17. Significant RAEs were observed from U8 to U19 and at U22. RAEs continuously decreased from U8 (large effect) to U14 (small effect). The present results show that differences in performance arise from the comparison of athletes in AGs. Thus, going beyond AGs and using exact CA, Q4 athletes could benefit from a realistic performance comparison, which promotes fair performance evaluation, un-biased talent development, realistic feedback, and long-term participation.
OBJECTIVES: To provide normative data and establish percentile curves for long-course (50m pool length) swimming events and to compare progression of race times longitudinally for the various swimming strokes and race distances. DESIGN: Descriptive approach with longitudinal tracking of performance data. METHODS: A total of 2,884,783 race results were collected from which 169,194 annual best times from early junior to elite age were extracted. To account for drop-outs during adolescence, only swimmers still competing at age of peak performance (21-26years) were included and analyzed retrospectively. Percentiles were established with z-scores around the median and the Lambda-Mu-Sigma (LMS) method applied to account for potential skewness. A two-way analysis of variance (ANOVA) with repeated measure and between-subject factor was applied to compare race times across the various events and age groups. RESULTS: Percentile curves were established based on longitudinal tracking of race times specific to sex, swimming stroke, and race distance. Comparing performance progression, race times of freestyle sprint events showed an early plateau with no further significant improvement (p>0.05) after late junior age (15-17years). However, the longer the race distance, the later the race times plateaued (p
OBJECTIVE: To establish reference data on required competition age regarding performance levels for both sexes, all swimming strokes, and race distances and to determine the effect of competition age on swimming performance in the context of other common age metrics. In total, 36,687,573 race times of 588,938 swimmers (age 14.2 +/- 6.3 years) were analyzed. FINA (Federation Internationale de Natation) points were calculated to compare race times between swimming strokes and race distances. The sum of all years of race participation determined competition age. RESULTS: Across all events, swimmers reach top-elite level, i.e. > 900 FINA points, after approximately 8 years of competition participation. Multiple-linear regression analysis explained up to 40% of variance in the performance level and competition age showed a stable effect on all race distances for both sexes (beta = 0.19 to 0.33). Increased race distance from 50 to 1500 m, decreased effects of chronological age (beta = 0.48 to - 0.13) and increased relative age effects (beta = 0.02 to 0.11). Reference data from the present study should be used to establish guidelines and set realistic goals for years of competition participation required to reach certain performance levels. Future studies need to analyze effects of transitions between various swimming strokes and race distances on peak performance.
PURPOSE: To explore reasonable application purposes and potential confounders of the Swiss-Ski Power Test (SSPT) that is, since 2004, annually performed by all youth competitive alpine skiers of the under-16-years age category in Switzerland. METHODS: Preseason SSPT results (8 individual tests on anaerobic and aerobic capacity, muscle strength, and speed and coordination) of 144 skiers (57 female and 87 male) age 14.5 (0.7) years were analyzed along with anthropometry and biological age. Skiing performance was quantified as the actual performance points according to the Swiss national ranking. After the SSPT tests, skiers were prospectively monitored over 12 months using the Oslo Trauma Research Center questionnaire. Data were analyzed using multivariate analysis of variance, Pearson correlations, and multiple linear/binary logistic regression models. RESULTS: Biological maturation and SSPT results differed between sexes and age (P < .05). For males, SSPT results in the subdisciplines Swiss Cross, 1-leg 5-hop, and standing long jump were correlated to maturity offset, while for females only the obstacle run was related. High box jump and Swiss Cross scores were associated with skiing performance (P < .05). However, none of the SSPT subdisciplines was related to traumatic and overuse injuries (P < .05). CONCLUSIONS: The SSPT is a broadly implementable and cost-effective field test providing a general fitness profile of youth skiers. Around the growth spurt, differences in biological maturation should be considered. While SSPT results showed association with skiing performance, the test in its current form is limited for identifying injury-relevant physical deficiencies. Consequently, more specific tests may be required.
Bone maturity is an indicator for estimating the biological maturity of an individual. During adolescence, individuals show heterogeneous growth rates, and thus, differences in biological maturity should be considered in talent identification and development. Radiography of the left hand and wrist is considered the gold standard of biological maturity estimation. The use of ultrasound imaging (US) may be advantageous; however, its validity and reliability are under discussion. The aims of this scoping review are (1) to summarize the different methods for estimating biological maturity by US imaging in adolescents, (2) to obtain an overview of the level of validity and reliability of the methods, and (3) to point out the practicability and usefulness of ultrasound imaging in the field of youth sports. The search included articles published up to November 2022. The inclusion criteria stipulated that participants had to fall within the age range of 8 to 23 years and be free of bone disease and fractures in the region of interest. Nine body regions were investigated, while the hand and wrist were most commonly analyzed. US assessment methods were usually based on the estimation of a bone maturity stage, rather than a decimal bone age. Furthermore, 70% of the assessments were evaluated as applicable, 10% expressed restraint about implementation, and 20% were evaluated as not applicable. When tested, inter- and intra-rater reliability was high to excellent. Despite the absence of ionization, low costs, fast assessment, and accessibility, none of the US assessments could be referred to as a gold standard. If further development succeeds, its application has the potential to incorporate biological age into selection processes. This would allow for more equal opportunities in talent selection and thus make talent development fairer and more efficient.
In football, annual age-group categorization leads to relative age effects (RAEs) in talent development. Given such trends, relative age may also associate with market values. This study analyzed the relationship between RAEs and market values of youth players.; Age category, birthdate, and market values of 11,738 youth male football players were obtained from the "transfermarkt.de" database, which delivers a good proxy for real market values. RAEs were calculated using odds ratios (OR) with 95% confidence intervals (95%CI).; Significant RAEs were found across all age-groups (; p; < 0.05). The largest RAEs occurred in U18 players (Q1 [relatively older] v Q4 [relatively younger] OR = 3.1) ORs decreased with age category, i.e., U19 (2.7), U20 (2.6), U21 (2.4), U22 (2.2), and U23 (1.8). At U19s, Q1 players were associated with significantly higher market values than Q4 players. However, by U21, U22, and U23 RAEs were inversed, with correspondingly higher market values for Q4 players apparent. While large typical RAEs for all playing positions was observed in younger age categories (U18-U20), inversed RAEs were only evident for defenders (small-medium) and for strikers (medium-large) in U21-U23 (not goalkeepers and midfielders).; Assuming an equal distribution of football talent exists across annual cohorts, results indicate the selection and market value of young professional players is dynamic. Findings suggest a potential biased selection, and undervaluing of Q4 players in younger age groups, as their representation and market value increased over time. By contrast, the changing representations and market values of Q1 players suggest initial overvaluing in performance and monetary terms. Therefore, this inefficient talent selection and the accompanying waste of money should be improved.
Objectives To provide normative data and establish percentile curves for long-course (50 m pool length) swimming events and to compare progression of race times longitudinally for the various swimming strokes and race distances. Design Descriptive approach with longitudinal tracking of performance data. Methods A total of 2,884,783 race results were collected from which 169,194 annual best times from early junior to elite age were extracted. To account for drop-outs during adolescence, only swimmers still competing at age of peak performance (21–26 years) were included and analyzed retrospectively. Percentiles were established with z-scores around the median and the Lambda-Mu-Sigma (LMS) method applied to account for potential skewness. A two-way analysis of variance (ANOVA) with repeated measure and between-subject factor was applied to compare race times across the various events and age groups. Results Percentile curves were established based on longitudinal tracking of race times specific to sex, swimming stroke, and race distance. Comparing performance progression, race times of freestyle sprint events showed an early plateau with no further significant improvement (p > 0.05) after late junior age (15–17 years). However, the longer the race distance, the later the race times plateaued (p
The aim of the study was to investigate the effect of start and turn performances on race times in top-elite female swimmers and provide benchmarks for all performance levels, all swimming strokes, and all race distances of the European Short-Course Championships (EC). The individual races (n = 798) of all female competitors (age: 20.6 ± 3.9 years, FINA points: 792 ± 78) were videomonitored for subsequent analysis of start and turn performances. Benchmarks were established across all competitors of each event based on the 10th, 25th, 50th, 75th, and 90th percentiles. Start and turn performances contributed up to 27.43% and 56.37% to total race time, respectively. Mechanistic analysis revealed that the fastest swimmers had the lowest contribution of the acyclic phases to race time. Therefore, relative to their faster race times, these swimmers were even faster during starts and turns. Multiple linear regression analysis showed large effects of turn performance on 50, 100, 200, 400, and 800 m race times (β = 0.616, 0.813, 0.988, 1.004, and 1.011, respectively), while the effect of start performance continuously decreased the longer the race distance. As turn performance may be the distinguishing factor in modern short-course races, benchmarks should be used to set goals and establish training guidelines depending on the targeted race time.
Zielsetzung Umfassende Evaluation der Durchführbarkeit und Wertigkeit der Magnetresonanztomographie (MRT) zur Skelettalterbestimmung von gesunden männlichen Jugendlichen. Material und Methoden Im Rahmen dieser Querschnittsstudie wurden im November 2019 N = 63 männliche Fußballspieler ohne chronische Vorerkrankungen im Alter von 10 – 13 Jahren (Mittelwert: 12,35 ± 1,1 Jahre) an einem 3 Tesla MRT untersucht. Es erfolgte die Akquisition dreier nativer Sequenzen: (1) Coronare T1-gewichtete TSE, (2) Coronare PD-gewichtete TSE und (3) T1-gewichtete 3D VIBE. Anschließend wurden die MRTs von drei verblindeten Radiologen mit unterschiedlichen Erfahrungslevels unabhängig ausgewertet: (1) Kinderradiologe, (2) > 20 und (3)
To investigate the freestyle swimming sprint start performance before and after 6 weeks of maximal strength compared with vertical jump training. With a between-group repeated-measure design, 21 junior swimmers (12 female and 9 male) competing in national and international championships performed 2 weekly sessions of either maximal strength (heavy-loaded back squat and deadlift exercise) or vertical jump training (unloaded box jumps) for 6 weeks during the precompetition phase of the seasonal main event. Session ratings of perceived exertion were used to compare the load of both training programs. Before and after the training period, sprint start performance was investigated on a starting block equipped with force plates synchronized to a 2-dimensional motion capture system. Total training load did not differ between the 2 groups. Sprint start performance and most kinematic and kinetic parameters remained unaffected. In pooled data of the U17 swimmers, however, 5-m, 15-m, and 25-m split times were improved with maximal strength (p = 0.02, 0.03, and 0.01), but not with vertical jump training (p = 0.12, 0.16, and 0.28). Although there was no global effect, focus on the subgroup of U17 swimmers showed an improved sprint start performance with 2 sessions of maximal strength training integrated into a 16-hour training week. Although outcomes of the conditioning program seemed to be affected by the training history and performance level of the athletes involved, strength and conditioning coaches are encouraged to introduce maximal strength training at a young age.
The aim of the present study was to investigate prospectively the role of biological maturity status, anthropometric percentiles, and core flexion to extension strength ratios in the context of traumatic and overuse injury risk identification in youth ski racing. In this study, 72 elite youth ski racers (45 males, 27 females) were prospectively observed from the age of 10 to 14 years. Anthropometric parameters, biological maturity status, and core flexion to extension strength ratios were assessed twice per year. Type and severity of traumatic and overuse injuries were prospectively recorded during the 4 years. Generalized estimating equations were used to model the binary outcome (0: no injury; 1: ≥1 injury). Factors tested on association with injury risk were sex, relative age quarter, age, maturity group, puberty status, core flexion to extension strength ratio, height percentile group, and weight percentile group. In total, 104 traumatic injuries and 39 overuse injuries were recorded. Age (odds ratio (OR) = 3.36) and weight percentile group (OR = 0.38) were significant risk factors for traumatic injuries (tendency: pubertal status). No significant risk factor for overuse injuries was identified (tendency: maturity group, puberty status, height percentile group). Future studies should focus on identifying risk factors for overuse injuries; growth rates might be of importance.
Modern talent identification (TID) and talent development (TD) models should include biologicaldevelopment. This requires practicable methods for the consideration of biological age (BA) andrelative age (RA). Until 2008, most Swiss sports federations selected young athletes on the basis ofcurrent competition results rather than development potential. This meant that many of these talentselection processes failed to integrate important indicators when assessing young talent. Because ofthese shortcomings, a new standardised national talent selection instrument for all Swiss sportsfederations was developed. In addition to having six major assessment criteria, the instrument includesbiological development, which is subdivided into BA, RA, and relative age effects (RAEs).However, in the current sports system, the participants are categorised into annual age groups toreduce the developmental differences during childhood and adolescence. In this regard, anunfortunate problem remains because of the potential for RA and BA differences among individualswithin an annual age cohort. This means that in many TID processes, the athletes do not have equalopportunities, the resources are used inefficiently, and potential talent is lost.This thesis summarizes the last eight years of research in RA and BA. Questions arose about theprevalence and evolution of RAEs at the various development stages and selection levels. Furthermore,gaps exist in the research on RAEs in female athletes. The number of extant studies was limited, andthe data were inconsistent. Therefore, this cumulative habilitation aims to show: (1) the prevalence ofRAEs by sport type, competition level, and gender; (2) the underlying mechanisms in RAEs; and (3) thepossible approaches for considering BA and RA in the selection process.Studies on RA and BA have shown that even a small age difference of a few months could exert asignificant effect on talent selection and TD. The current sports system, which uses chronological age4categories, results in the selection of a disproportionate number of biologically and/or chronologicallyolder athletes. This phenomenon has been observed throughout the Swiss TD program, particularlywith regard to male athletes. RAEs also influence the selection of female athletes; therefore, theseeffects must be taken into account. Comparisons of sports have shown that high physical demands andhigh performance density (many selection levels) strengthen RAEs.Differences in BA are the principal cause of RAEs. This can lead to performance differences, which,along with parental influence, can trigger selection and self-selection processes. The most importantenvironmental factors are the popularity (i.e. number of participants and economic factors),requirement profiles, and selection levels of the sports. The athletes who are selected benefit fromgreater support, better training, access to higher competition levels, higher involvement, and positivefeedback, which have a positive influence on performance. This leads to an upward spiral for athletesat higher BAs and RAs and a negative spiral for those at lower BAs and RAs (the “vicious circle”). ”False”talent is encouraged, and ”true” talent is lost. Thus, many athletes with the potential for success inadulthood are overlooked. The suggested solutions to counteract the differences in RA and BA are: (1)the implementation of corrective adjustments to reduce RAEs and (2) low-dose hand–wrist imaging orcoaches’ subjective evaluations to account for BA. TID programmes must seek to reduce the risk ofRAEs by raising awareness, monitoring the athletes’ BAs, and avoiding early selection or deselection.If selection is necessary because of a lack of resources, RA and BA considerations should be integratedinto a long-term multidisciplinary approach. With the implementation of these measures, TID can bemore equitable, and the available resources can be used more efficiently.
Objectives: (1) Generate accurate estimates of the relationship between decimal age (i.e., chronologicaland relative) with swimming performance based on longitudinal data. (2) Determine whether correctiveadjustment procedures can remove Relative Age Effects (RAEs) from junior/youth swimming.Design: Longitudinal and repeated years of cross-sectional performance data were examined.Methods: (1) Participants were 553 male 100 m Freestyle swimmers (10–18 years) who participatedin ≥five annual events between 1999–2017. Growth curve modelling quantified the relationship betweenage and swimming performance, permitting corrective adjustment calculations. (2) Participants wereN = 2141 male 100 m Freestyle swimmers (13–16 years) who swam at state/national events in 2015–2017.Relative age distributions for ‘All’, ‘Top 50%’, ‘25%’ and ‘10%’ of swimming times were examined basedon raw and correctively adjusted swim times. Chi-square, Cramer’s V and Odds Ratios (OR) determinedwhether relative age (quartile) inequalities existed according to age-groups, selection level and correc-tively adjusted swim times.Results: Based on raw swim times, for ‘All’ swimmers RAEs was evident at 13 and 14 years-old anddissipated thereafter. But, RAE effect sizes substantially increased with selection level, with large-mediumeffects between 13–15 years-old (e.g., 15 years — Top 50% Q1 v Q4 OR = 2.28; Top 10% = 6.02). However,when correctively adjusted swim times were examined, RAEs were predominantly absent across age-group and selection levels.Conclusions: With accurate longitudinal reference data, corrective adjustment procedures effectivelyremoved RAEs from 100 m Freestyle swimming performance, suggesting the potential to improve swim-ming participation experience and performance evaluation.
