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.
Turn sections represent the second largest part of total race time in 1500 m freestyle races and may substantially affect race results. Therefore, the aim of the study was to investigate individual race strategies and compare the effect of start, swim, and turn performances between short-course and long-course races. Video footages were collected from all 16 male finalists at the 2018 short and 2019 long-course World swimming championships (age 23.06 ± 2.3 years, FINA points 941 ± 42) for subsequently analysis of start, turn, and swim performance.; The larger number of turns in short-course races resulted in significantly faster race times (p = 0.004), but slower mean turn times compared to long-course races (p
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.
The aims of the study were to assess the robustness and non-reactiveness of wearable near-infrared spectroscopy (NIRS) technology to monitor exercise intensity during a real race scenario, and to compare oxygenation between muscle groups important for cross-country skiing (XCS). In a single-case study, one former elite XCS (age: 39 years, peak oxygen uptake: 65.6 mL/kg/min) was equipped with four NIRS devices, a high-precision global navigation satellite system (GNSS), and a heart rate (HR) monitor during the Vasaloppet long-distance XCS race. All data were normalized to peak values measured during incremental laboratory roller skiing tests two weeks before the race. HR reflected changes in terrain and intensity, but showed a constant decrease of 0.098 beats per minute from start to finish. Triceps brachii (TRI) muscle oxygen saturation (SmO; 2; ) showed an interchangeable pattern with HR and seems to be less affected by drift across the competition (0.027% drop per minute). Additionally, TRI and vastus lateralis (VL) SmO; 2; revealed specific loading and unloading pattern of XCS in uphill and downhill sections, while rectus abdominus (RA) SmO; 2; (0.111% drop per minute) reflected fatigue patterns occurring during the race. In conclusion, the present preliminary study shows that NIRS provides a robust and non-reactive method to monitor exercise intensity and fatigue mechanisms when applied in an outdoor real race scenario. As local exercise intensity differed between muscle groups and central exercise intensity (i.e., HR) during whole-body endurance exercise such as XCS, NIRS data measured at various major muscle groups may be used for a more detailed analysis of kinetics of muscle activation and compare involvement of upper body and leg muscles. As TRI SmO; 2; seemed to be unaffected by central fatigue mechanisms, it may provide an alternative method to HR and GNSS data to monitor exercise intensity.
The aim of the study was to investigate key performance indicators for the individual pool-based disciplines of competitive lifesaving regarding strength, flexibility, sprint and endurance swimming performance, anthropometric characteristics, and technical skills specific to competitive lifesaving. Data were collected from Swiss national team members (seven males: age 19 ± 2 yrs, body mass 77 ± 11 kg, body height 177 ± 7 cm and seven females age 21 ± 5 yrs, body mass 64 ± 6 kg, body height 171 ± 4 cm) competing at the 2019 European lifesaving championships. Potential key performance indicators were assessed with race times derived from the 2019 long-course season using Spearman's correlation coefficient. Large and significant correlations showed that sprint, i.e., 50 m freestyle performance (; r; ≥ 0.770), was related to race time of all pool-based disciplines, rather than endurance swimming performance. Additionally, significant correlations revealed upper body strength, i.e., bench press (; r; ≥ -0.644) and pull (; r; ≥ -0.697), and leg strength (; r; ≥ -0.627) as key performance indicators. Importance of the lifesaving-specific skills, anthropometric characteristics, and core strength varied between the disciplines. Flexibility was not significantly related to race times of competitive lifesaving. The present study showed that sprint swimming performance, upper body, and leg strength are particularly important for competitive lifesaving. As other physical and technical requirements varied between the pool-based disciplines, coaches may use the present key performance indicators to establish training guidelines and conditioning programs as well as prioritize skill acquisition in training to specifically prepare athletes for their main disciplines.
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.
