Scanning is an important perceptual skill that enables football players to gather information about opponents, teammates and the environment in real-time. This study investigated scanning before and during ball possession and its effect on the success of the subsequent action in U19 female footballers. Sixty-one elite and grassroots players (age: 16.7 ± 1.4) were recruited and analysed during 4v4 small-sided games. A total of 2010 game situations were video recorded for subsequent manual tagging. Multilevel logistic regression models revealed that elite players performed significantly more scans prior to first ball contact than their grassroots counterparts, but the number of scans performed during ball possession did not differ between competition levels. Furthermore, scans before and during ball possession positively influenced player's performance, whereas opponent pressure negatively influenced the success of subsequent actions, regardless of competition level. Differentiating between various subsequent actions revealed that scans before ball possession had a positive effect on the success of dribblings and passes, whereas scans during ball possession only had a positive effect on dribblings. Our results underline the importance of scanning in youth female football. These findings should be considered by coaches in the long-term development of players to increase the level of performance at elite age.
In this study, we tested the hypothesis that augmented feedback (AF) training can improve both perceptual-cognitive and/or motor skills specific to soccer.; Three groups of young elite players (U14-U15 categories) performed a test consisting in passing the ball as accurately and as quickly as possible towards a visual target moving briefly across a large screen located at 6 meters from the player. The performed task required players to correctly perceive the target, anticipate its future location and to adequately adjust the pass direction and power. The control group (CON) performed normal soccer training and was compared with two visuomotor training groups (AF and No-Feedback NF) that followed the same training regime but integrated series of 32 passes three times per week over a seventeen-day period into their normal soccer training. Objective measurements of the passing performance were provided using a high-technology system (COGNIFOOT) prior to, during and after training. During training, only players of the AF-group received visuo-auditory feedback immediately after each trial informing them about the accuracy of their passes.; The results show that only players of the AF-group significantly improved passing accuracy, reactiveness, and global passing performance (+22 %) whereas the NF-group only improved passing accuracy. None of these parameters was improved in the CON-group. The objectively measured changes in passing performance were compared to the more subjectively judged passing performance provided by coaches and players. Coaches' judgments were more reliable than players' judgments and exhibited a training group effect comparable to the ones objectively measured by COGNIFOOT.; This study provides evidence that the training of cognitive motor performance in soccer players highly benefits from the use of augmented feedback.
Consideration of maturity is recommended in the talent identification and development process. Skeletal age (SA), prediction of age of peak height velocity (APHV) and an estimation of biological maturation by coaches’ eye of 121 soccer players were compared. The SA of soccer players was 13.9 ± 1.1 years, and did not differ significantly from chronological age (CA). Agreement between the SA-CA classifications and APHV was 65.5%. Spearman rank-order correlation (rs) between maturity classifications was moderate, kappa (k) was 0.25. Agreement between SA-CA classifications and coaches’ eye was 73.9%. The rs between maturity classifications was strong, k was 0.48, which was better than the widely used APHV assessment. Therefore, estimations of experienced coaches seem to be an acceptable alternative method for classifying maturity in youth athletes.
Physical performance is highly dependent on maturity. Therefore, consideration of maturity is recommended in the talent identification process. To date, skeletal age (SA) is assessed using X-ray scans. However, X-rays are associated with a tenfold higher radiation compared to dual energy X-ray absorptiometry (DXA). The aim of the study was to validate SA assessments in male soccer players with the DXA-technique. Paired X-ray and DXA scans of the left hand of 63 Swiss U-15 national soccer players were performed. SA assessments were performed twice by two blinded raters using Tanner and Whitehouse’s reference technique. Intra-, and interrater reliability as well as agreement between both techniques were tested. Intra-, and interrater reliabilities were excellent. Bland-Altman plots showed that SA assessments between X-ray and DXA differed by -0.2 years and 95% limits of agreement were ±0.6 years. Therefore, DXA offered a replicable method for assessing SA and maturity in youth soccer players.
Background: The second-to-fourth digit-length ratio (2D:4D) may be a correlate of prenatal sex steroids, and it has been linked to sporting prowess. The aim of the study was to validate dual-energy X-ray-absorptiometry (DXA) as a technique to assess 2D:4D in soccer players under 15 years of age (U-15). Methods: Paired X-ray and DXA scans of the left hands of 63 male U-15 elite soccer players (age: 14.0 ± 0.3 years) were performed, and 2D:4D was then compared between the two techniques. The 2D:4D measurements were performed twice by two blinded raters. Intrarater and interrater reliability, as well as agreement between the X-ray and the DXA assessments, were tested. Results: Intrarater reliabilities of both raters using X-ray with intraclass correlation coefficients (ICCs) of 0.97 and 0.90 were excellent. Using DXA, the ICCs were 0.90 and 0.91 thus also showing excellent reliability. Interrater reliabilities were excellent using both the X-ray (ICC of 0.94) and the DXA (ICC of 0.90), assessments respectively. Bland-Altman plots demonstrated that the 2D:4D ratios of the two raters did not differ significantly between the X-ray and the DXA assessments. The standard errors of estimate were 0.01 for both techniques. The 95% limits of agreement of ±0.018 (±2.0%) and ±0.023 (±2.6%), respectively, were within the acceptable tolerance of 5%, and showed very good agreement. Conclusion: DXA offered a replicable technique for assessing 2D:4D in youth soccer players. Therefore, the DXA technique seems to be an alternative method for evaluating 2D:4D in youth sports.
Introduction Biological maturation (BM) of young athletes is implicit in models of talent identification, selection, and development.In several elite team sports proportionally more players were detected who are advanced (early) in BM and proportionally fewer players who are delayed (late) in BM (Malina, et al. 2012). The aims of the present study were twofold: firstly, to assess the biological maturation of elite under-15 (U-15) soccer players and secondly, to determine if coaches are able to classify BM of soccer players compared to a categorization by X-ray. Method Subjects: 119 male Swiss soccer players (age: 14.0±0.3 years; weight: 53.0±8.7 kg; height: 164.9±8.4 cm) of the U-15 national team. Measurements: X-rays of the left wrist-hand were performed to evaluate BM. Bone age assessment was calculated blinded by a trained observer according to the reference method of Tanner &Whitehouse (1975). Players were classified as late, on time (normal) or early maturing on the basis of the difference between skeletal age (SA) and chronological age (CA). On time was defined as an SA within 1.0 year of CA. Early maturing was defined as an SA in advance of CA by more than 1.0 year. Late maturing was defined as an SA younger than CA by more than 1.0 year. Additionally three coaches observed the players during a training session and did a visual subjective assessment applying the same maturity categories (late, normal, early developed). Statistics: Cohen unweighted kappa coefficients were calculated to evaluate the concordance of maturity classifications using IBM SPSS. The level of significance was set at p
Relative age effects (RAEs) refer to age differences among athletes in the same selection year. This study analyzed birth date distributions of 301,428 female athletes (aged 10-20 yr.) in Swiss Youth sports and the subgroup (n = 1,177) of the National Talent Development Program (TDP) in individual sports. Comparisons showed significant RAEs in the distribution of athletes' birth dates in alpine skiing, tennis, athletics, fencing, and snowboarding. Significant "reverse" RAEs with an overrepresentation of athletes at the end of the year were found in table tennis. In the TDP, significant RAEs were found in alpine skiing and tennis. No RAEs were detected in athletics. In table tennis, fencing, and snowboarding, "reverse" RAEs were found. Clearly, RAEs are complex and vary across individual sports for females.
Previous research has shown that young male soccer players who are born early in a cohort are overrepresented on elite soccer teams. Selection advantages such as this have been termed 'relative age effects' (RAEs). Few studies have examined RAEs in elite women's youth soccer. Therefore, the aim of this study is to investigate the occurrence of RAEs in the Fédération Internationale de Football Association (FIFA) U-17 Women's World Cup competition and their link to playing positions. In the entire cohort of 672 players, we found significant RAEs in the geographical zones of Europe and North and Central America, no RAEs in the zones of Asia, Oceania, and South America, and significant inverse RAEs in the zone of Africa. Additionally, significant RAEs were found for goalkeepers and defenders from Europe and North and Central America. Inverse RAEs occurred for African goalkeepers, defenders, and strikers. Goalkeepers of all zones were significantly taller than players of all other playing positions. The results of this study show that remarkable RAEs do exist at elite women's youth soccer. Similar to men's soccer, there is a bias toward the inclusion of relatively older players, and a link between RAEs and playing positions.
Abstract Relative age effects (RAEs) refer to age differences between children in the same selection year. The present study investigated the prevalence of RAEs and their link to playing positions in Swiss junior soccer. Swiss male junior soccer players (n50,581) representing 11% of the age-matched population members of extra-curricular soccer teams were evaluated to determine the influence of RAEs on Swiss junior soccer. Subgroups were the national talent development programme (n2880), and U-15 to U-21 national teams (n630). While no RAEs were found for the self-selected extracurricular soccer teams or for the U-20 teams (P0.05), significant RAEs were found for talent development and the national U-15 to U-19 and U-21 teams (PB0.01). Additionally, defenders born early in the year were significantly overrepresented compared with goalkeepers, midfielders and strikers (PB0.05). In Switzerland, RAEs apparently have substantial influence on the talent identification process for U-15 to U-18 teams, significantly influencing the selection of players in talent development teams already at an early age, but do not influence self-selected participation in extracurricular soccer. Additionally, the RAE bias may be a predictor of playing positions in national teams. To minimise RAEs in Swiss soccer, systematic education for all coaches regarding RAEs should be established, in addition to a slotting system with rotating calendar cut-off dates.
Abstract The high performance unit within the Swiss Federal Institute of Sports Magglingen (SFISM) is chartered with supporting talented athletes via its collective inputs to students, athletes, coaches and national sporting federations. This is achieved by drawing upon the multi-disciplinary expertise of practitioners in the areas of sports medicine, recovery and rehabilitation, training science, sports psychology, nutrition, endurance and power physiology, strength and conditioning, and data management. This critical mass of specialists provides opportunities to collaborate “broadly” across a specific talent theme (e.g. on what basis should we select future sporting talent?), as well as the provision of sufficient content expertise to provide “deeper” knowledge and insights related to these interdisciplinary discussions (e.g. how can we account for biological maturity?). Therefore, this paper presents an example of the “broad” interdisciplinary work undertaken by SFISM to improve talent selection, and the complementary “deep” work used to investigate biological maturation as one component of this process. New and ongoing projects will continue to harness the collective potential of the multidisciplinary experts to better understand the processes of talent identification, selection, and development at the broadest and deepest levels. Our collective ability to support Switzerland’s best and brightest talent will require us to maximise the considerable expertise of the many stakeholders which influence and impact on development.
Abstract Relative age effects (RAEs) refer to age differences in the same selection year. In this study, 6,229 female soccer players representing the entire Swiss female soccer population were evaluated to determine the prevalence of RAEs in Swiss women’s soccer. Significant RAEs existed in the self-selected extracurricular (n = 2987) soccer teams and the subgroup of talent development teams (n = 450) in the 10 to14 age category. No significant RAEs were found for players 15 years of age or older (n = 3242) and the subgroup of all national teams (n = 239). Additionally, significantly stronger RAEs were observed in defenders and goalkeepers compared to midfielders in national teams. Our findings show that in Switzerland, RAEs apparently influence the self selection and talent selection processes of women’s soccer in the 10 to 14 age category. However, in contrast to male soccer we found no RAEs in elite women’s soccer teams.
Trotz grundsätzlich erfolgreicher Arbeit im Schweizer Nachwuchsleistungssport entschied sich Swiss Olympic, die Talentauswahl national zu steuern und ein sportartübergreifendes Talentselektionsinstrument für die Sportverbände zu entwickeln. Auf Grundlage von wissenschaftlichen Erkenntnissen, Tra...inerwissen und unter Beachtung der Praxistauglichkeit wurden die Beurteilungskriterien und -methoden für die prognostische, integrative, systematische Trainereinschätzung (PISTE) definiert. 2009 begann die Implementierung. Mittlerweile wird das Talentselektionsinstrument landesweit in 90 Prozent der im Nachwuchsleistungssport aktiven Sportverbände angewendet.
Abstract Several studies (on an inclined platform or with special shoes) have reported improved jump performance when the ankle was in a dorsiflexion (DF) position. The present study aims to test whether shoes inducing moderate DF modify vertical jump performance and energy cost. Twenty-one young, healthy female subjects (30 +/- 6 yr, 58 +/- 6 kg, O2max 45 +/- 3 mLxkg-1xmin-1, mean +/- SD) participated in the study. Jump performance was tested with subjects either wearing 4 degrees DF or standard (S) shoes. The jump tests (performed on a force platform) consisted of squat jump (SJ), countermovement jump (CMJ), and continuous jumps (CJ) during 15 seconds. Measured parameters were jump height, speed at take off, and maximal and average power. Oxygen uptake was measured on a treadmill while subjects ran at 95% of the anaerobic threshold during a 7-minute steady-state period. As compared with S shoes, DF shoes significantly improved the height of SJ (31 +/- 4 cm vs. 34 +/- 4 cm, p = 0.0001), CMJ (32 +/- 4 cm vs. 34 +/- 4 cm, p = 0.0004), and CJ (17.5 +/- 4.2 cm vs. 22.0 +/- 6.0 cm, p = 0.0001). Speed at take off was also significantly higher. Mean power significantly increased in SJ and CJ but not in CMJ. Oxygen uptake was not different between conditions (p = 0.40). Dorsiflexion shoes induce a significant increase in jump performance. These results are in accordance with the concept that a DF of the ankle may induce an increase of the length and strength of the triceps surae (higher torque). However, wearing DF shoes did not require more energy during running. Dorsiflexion shoes could be used to increase jump performance in several sports such as volleyball in which jump height is essential.
Abstract The aim of the present study was to compare electromyographic activity during fitness exercises, walking, and running among 3 different dorsiflexion shoes (+2 degrees , +4 degrees , and +10 degrees ) and standard shoes (-4 degrees ). The 3 different dorsiflexion shoes tested in this study have a curvature placed in the middle of the sole. This design was specially projected to decrease the metatarsus flexion. Electromyographic activity of 9 lower limb muscles was measured on 12 healthy female subjects during 5 fitness exercises (unload squat, side and front step, submaximal ballistic plantar flexion, and lunge exercise), and during running (10 km x h(-1)) and walking (4.5 km x h(-1)) on a treadmill. EMG signal was analyzed with the root mean square (RMS) and integrated EMG. All RMS data measured during these exercises were expressed as percentages of maximum voluntary isometric contraction. The results show that dorsiflexion affects muscle recruitment and reorganizes the motor pattern. The general tendency was that the tibialis anterior activity increased with dorsiflexion. However, an optimal dorsiflexion existed for various exercises. It is concluded that shoes with moderate dorsiflexion can activate lower limb muscles differently compared with both standard shoes and shoes with large dorsiflexion during submaximal exercises and locomotion.
