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Talent identification in youth soccer is a complex decision-making process that requires selectors to judge an individual’s future potential. While there has been considerable research into the performance characteristics of talented players, investigators have limited consensus on the best approach to assess soccer skills. Most of the research explains why we should measure skill instead of how we go about assessing skill. Therefore, the current scoping review aimed to synthesize and analyse skill assessments in youth soccer. Four electronic databases (EBSCO, ProQuest, PubMed, and Scopus) were searched for relevant studies. Information regarding the sample characteristics and methodological design of the skill assessments were extracted, synthesised, and presented in a qualitative analysis. Overall, 226 skill assessments were used across the 93 included studies. Male players from different ages (U/7-U/23) and playing levels comprised most (89%) of the collective sample. The majority of assessments were performed in settings not representative of football match-play (68%), focused on offensive skills (99%), and included skill outcome measures (95%). The variability of assessments highlights some confusion about the best way to assess soccer skill, potentially limiting selectors ability to identify skilful players. Ultimately, this will impact the number of quality players within the talent pool.

Introduction: In youth soccer, for examining injury prevention and exercise performance, most of the interventional studies concerning corrective postural asymmetries have applied general intervention programs, ignoring the specific individual corrective needs of each youth player separately. The aim, therefore, of the present study was to examine the effect of 8 weeks of an individualized corrective exercise intervention program on musculoskeletal asymmetries in young soccer players. Materials and Methods: Eighty young male soccer players (age: 14.4 ± 1.2 years; body height: 166.3 ± 9.6 cm; body mass: 59.1 ± 11.5 kg) participated in the current laboratory-based study. A battery of postural and musculoskeletal asymmetry evaluations were initially performed. After the completion of the initial assessment, each player was provided with an individual musculoskeletal asymmetry corrective exercise intervention program which lasted for 8-weeks, with the aim of restoring muscular asymmetries. Following the application of the intervention program, a re-evaluation of their musculoskeletal asymmetries was performed. Results: There was a significant improvement in the primary angle of trunk rotation (r = −0.56, p < 0.001), hamstring flexibility (right: r = −0.55, p < 0.001; left: r = −0.48, p < 0.001), hip external rotation (right: r = −0.46, p < 0.001; left: r = −0.26, p = 0.020), hip internal rotation (right: r = −0.26, p = 0.021; left: r = −0.35, p = 0.002), the opened-eyes Stork Test (right: r = −0.33, p = 0.003: left: r = −0.33, p = 0.003), the closed-eyes Stork Test (right: r = −0.39, p < 0.001; left: r = −0.43, p < 0.001), the Thomas test [right: (χ2(3) = 52.281, p = 0.001, γ^ = −0.751; left: (χ2(3) = 45.832, p = 0.001, γ^= −0.696)] and of ankle prone passive dorsiflexion (flexed knees) (χ2(2) = 13.019, p = 0.005, V = 0.285). Conclusions: An 8-week individual corrective intervention exercise program may improve postural and musculoskeletal asymmetry status in young male soccer players.

El estudio de los factores psicológicos relacionados con el rendimiento deportivo tiene un importante recorrido en la literatura científica. Conocer si existen diferencias de género en deportistas, cuáles son estas, y en qué aspectos se manifiestan es una cuestión que podría ayudar a mejorar la labor de entrenadores y técnicos deportivos. El objetivo de este estudio es determinar si existen diferencias de género en el perfil psicológico de futbolistas juveniles relacionado con el rendimiento deportivo. Se utilizó un diseño descriptivo transversal. La muestra objeto de estudio estuvo formada por un total de 329 jugadores juveniles de fútbol (46.8% varones y 53,2% mujeres), con una edad media de 17.02 (±1.50) años. Para la evaluación de las características psicológicas se utilizó el Cuestionario Características Psicológicas Relacionadas con el Rendimiento Deportivo (CPRD). Los resultados de este estudio indican que existen diferencias estadísticamente significativas entre varones y mujeres en control de estrés (CE), influencia de la evaluación del rendimiento (IER) y en cohesión de equipo (CH), con un tamaño del efecto de .51, .31 y .40 respectivamente. Los jugadores manifiestan puntuaciones mayores que las jugadoras en CE, es decir, gestionan mejor el estrés propio de la competición, y en IER, es decir, los jugadores gestionan mejor que las jugadoras el impacto que supone la evaluación de su rendimiento, el que hacen los otros (entrenadores, compañeros, padres/madres, etc.) y el que se hace a sí mismo. Sin embargo, las jugadoras presentan mejores puntuaciones en CH, es decir, manifiestan una mayor tendencia a trabajar en grupo y fortalecer el equipo. The study of psychological factors related to sports performance has an important track record in thescientific literature. Knowing if there are differences between male and female athletes, what they are, and in what aspects they manifest is an issue that could help improve the work of coaches and sports technicians. The aim of this study is to determine if there are gender differences in the psychological profile of youth soccer players related to sports performance. A descriptive cross-sectional design was used. The sample under study was formed by a total of 329 youth soccer players (46.8% male and 53,2% female), with an average age of 17.02 (± 1.50) years. The Psychological Characteristics Questionnaire Related to Sports Performance (CPRD) was used to evaluate psychological characteristics. The results of this study indicate that there are statistically significant differences between male and female in stress control (CE), influence of performance evaluation (IER) and in team cohesion (CH), with an effect size of .51, .31 and .40 respectively. The male players show higher scores than the female players in CE, that is, they better manage the stress of the competition, and in IER, that is, the male players manage better than the female players the impact of evaluating their performance, the one that others do (coaches, partners, fathers / mothers, etc.) and the one thatmakes itself. However, female players have better CH scores, that is, they show a greater tendency to work in groups and strengthen the team. O estudo de fatores psicológicos relacionados ao desempenho esportivo tem um histórico importante na literatura científica. Saber se existem diferenças entre atletas masculinos e femininos, o que são e em que aspectos eles se manifestam é uma questão que pode ajudar a melhorar o trabalho de treinadores e técnicos esportivos. O objetivo deste estudo é determinar se existem diferenças de gênero no perfil psicológico de jovens jogadores de futebol relacionados ao desempenho esportivo. Foi utilizado um desenho descritivo de corte transversal. A amostra estudada foi composta por um total de 329 jogadores de futebol juvenil (46,8% masculino e 53,2% feminino), com idade média de 17,02 (± 1,50) anos. O Questionário de Características Psicológicas Relacionadas ao Desempenho Esportivo (CPRD) foi utilizado para avaliar as características psicológicas. Os resultados deste estudo indicam que existem diferenças estatisticamente significantes entre meninos e meninas no controle do estresse (EC), influência da avaliação de desempenho (IER) e na coesão da equipe (HC), com um tamanho de efeito de 0,51, 0,31 e 0,40, respetivamente. Os jogadores pequenos apresentam pontuações mais altas do que as jogadoras da CE, ou seja, administram melhor o estresse da competição, e no IER, ou seja, os jogadores pequenos gerenciam melhor do que as jogadoras o impacto de avaliar seu desempenho, o que os outros fazem (treinadores, parceiros, pais / mães, etc.) e o que se faz. No entanto, as jogadoras têm melhores pontuações no HC, ou seja,mostram maior tendência a trabalhar em grupo e fortalecer a equipe.

Considering that most professional academies seek to optimize the early detection and physical development of their younger players, the purpose of this study was to examine the anthropometric and physical fitness characteristics in a large cross-sectional sample of youth soccer players in Eastern Europe, starting from a very young age during their in-season period. Three hundred and thirteen soccer players (n = 313), grouped into eight age categories, participated in the study. On the basis of chronological age, the group categories were: 7 (n = 26), 8 (n = 41), 9 (n = 46), 10 (n = 48), 11 (n = 42), 12 (n = 47), 13 (n = 43), and 14 years old (n = 20). The players underwent an anthropometric evaluation, flexibility, handgrip strength, vertical jump performance, speed, and agility assessments. A one-way multivariate analysis of variance (MANOVA) indicated significant differences in the anthropometric and physical fitness variables based on chronological age (F = 13.40, p < 0.05, Wilk’s Λ = 0.08, partial η2 = 0.30). Concurrently, there were significant growth and physical fitness differences even in players born in the same chronological year. It is believed that the results have important practical implications, especially for those involved in youth soccer. Based on our results, coaches should contemplate speed and agility development in training sessions starting from a much younger age, as sprinting while changing directions has been considered an essential prerequisite in soccer.

The purpose of this study was to evaluate differences in multiple athletic performances, and to examine associations between athletic performance and Functional Movement Screen (FMS) in young soccer players. Forty-one soccer players were tested on peak height velocity (PHV), 5-, 10-, and 30-m sprint times, 505 change of direction (505 COD), Y-reactive agility tests, countermovement jump (CMJ), and squat jump (SJ) height. Significant main effects (P

Earlier research shows that wide regional variations exist in the success of athletes' talent development but is divided with respect to the role of urbanity: both low and high urbanity have been identified as settings that contribute to the presence of talent hotspots. In this article, we intend to provide more insight into the role of urbanity in talent development in Dutch football. We used public data on the regional background of male elite players (N = 825) and combined this with public data on municipal characteristics from Statistics Netherlands and other sources: urbanity, football participation, instructional resources and population composition effects (migration background and income of inhabitants). Linear regression analysis showed that football participation, the proportion of non-western migrants and median income predict "talent yield", i.e., the proportion of young people that reach an elite level in a municipality. Urbanity does not have an independent influence when the proportion of non-western migrants in the municipality is taken into account. The presence of instructional resources does not have an independent influence. The results suggest that characteristics of the built environment, such as indoor and outdoor play opportunities, may be less influential in talent development than previously assumed.

espanolObjetivo: Calcular el consumo maximo de oxigeno a traves de un test de campo submaximo (Yo-Yo de recuperacion intermitente I) y valorar la percepcion subjetiva del esfuerzo y la percepcion del grado de recuperacion entre jugadores y sus diferentes posiciones en el campo. Metodo: 32 jugadores de futbol masculino de 1a Division Andaluza Sub 15, realizaron el test de campo Yo-Yo de recuperacion intermitente I para calcular el consumo maximo de oxigeno, posteriormente se registro la percepcion de los esfuerzos y la frecuencia cardiaca. Resultados: Diferentes pruebas t comparando los datos obtenidos mostraron tan solo diferencias significativas en la frecuencia cardiaca tras recuperacion de 1’ entre centrocampistas vs delanteros, t(10)= 3.04, p Conclusion: Estos datos indican un mejor comportamiento cardiovascular en los centrocampistas, coincidiendo con lo datos existentes en la literatura. EnglishObjective: Calculate the maximum oxygen consumption during physical effort in a submaximal field test (Intermittent Recovery Yo-Yo I) and obtain subjective perception of effort and perception of degree of recovery between the different positions occupied by youth soccer’s on the field. Method: 32 male soccer players from the 1st Andalusian Division U15. The maximum oxygen consumption was calculated using the Intermittent Recovery Yo-Yo I field test, consequently efforts perception and heart rate was recorded. Results: Different t-test comparing the data obtained, only reflected significant differences between midfielders vs. forwards in heart rate after of 1’ recovery, t (10) = 3.04, p Conclusions: The data show a better cardiovascular performance in midfielders coincided with literature. portuguesObjetivo: Calcular o consumo maximo de oxigenio atraves de um teste de campo submaximo (Recuperacao intermitente Yo-Yo I) e avaliar a percepcao subjetiva do esforco e a percepcao do grau de recuperacao entre jogadores e suas diferentes posicoes em campo. Metodos: 32 jogadores de futebol do sexo masculino da 1a Divisao da Andaluzia Sub 15 realizaram o teste de campo Recuperacao intermitente Yo-Yo I para calcular o consumo maximo de oxigenio, posteriormente foram registradas a percepcao de esforcos e a frequencia cardiaca. Resultados: Diferentes testes t comparando os dados obtidos mostraram apenas diferencas significativas na frequencia cardiaca apos a recuperacao de 1' entre os medios e os avancados, t (10) = 3.04, p Conclusao: Esses dados indicam melhor comportamento cardiovascular em medios, coincidindo com o que existe na literatura.

This study aimed to analyze different predictive analytic techniques to forecast the risk of muscle strain injuries (MSI) in youth soccer based on training load data. Twenty-two young soccer players (age: 13.5 ± 0.3 years) were recruited, and an injury surveillance system was applied to record all MSI during the season. Anthropometric data, predicted age at peak height velocity, and skeletal age were collected. The session-RPE method was daily employed to quantify internal training/match load, and monotony, strain, and cumulative load over the weeks were calculated. A countermovement jump (CMJ) test was submitted before and after each training/match to quantify players’ neuromuscular fatigue. All these data were used to predict the risk of MSI through different data mining models: Logistic Regression (LR), Random Forest (RF), Support Vector Machine (SVM). Among them, SVM showed the best predictive ability (area under the curve = 0.84 ± 0.05). Then, Decision tree (DT) algorithm was employed to understand the interactions identified by the SVM model. The rules extracted by DT revealed how the risk of injury could change according to players’ maturity status, neuromuscular fatigue, anthropometric factors, higher workloads, and low recovery status. This approach allowed to identify MSI and the underlying risk factors.

The aim of the present study was to analyze the behavior of players in a standard small-sided game (SSG) according to the role played (offensive (OF), defensive (DF), and wildcard (W)) and its relationship with physical demands (PHYD), technical performance (TP), and internal load (RPE). A total of 24 young highly trained male soccer players (under 16: n = 12, under 19: n = 12) participated. During the SSG, the players alternated the three roles (OF, DF, and W). The duration of each repetition was 4 min with a passive rest of 3 min between them. Furthermore, it emphasized the high demand in all defensive parameters. In addition, DF roles showed higher values in PHYD and RPE, followed by the OF roles, and finally by the W roles. A complementary, positive moderate correlation was found between PHYD and RPE in the U16 dataset (r = 0.45, p &lt, 0.006). Very large positive correlations were also found between PHYD and RPE in the U19 and merged dataset (r = 0.78, p &lt, 0.001 and r = 0.46, p &lt, 0.63, respectively). This information could be useful for coaches in order to structure the roles in SSGs and control training load.

The U14, U15 and U16 infrastructure, which competes in the development leagues of a professional football team, was carried out with a total of 60 volunteer footballers with the participation of team players. 21 athletes from the U14, 19 from the U15 and 20 from the U16 age category participated in the study. In the study, height, body weight, vertical jump, 10m and 30m sprint and agility measurements of volunteer participants were made. Football players who born in the first half of the year and the second half of the year were compared, there was no significant difference between parameters. In the study, it was determined that the athletes born in the first months of the year show early physical development and have advantages in some performance parameters. Coaches should form the team by considering their biological maturation during the selection of their athletes for the team. The disadvantages of the relative age effect among athletes should be groups based on the birth months of the athletes and should try to prepare appropriate training programs for the groups.

Youth soccer performance is multifaceted, includes physical growth, biological maturation, and physical fitness, and is linked to the sporting environment to which the players are exposed. We aim to describe age-related associations in body physique, body composition, physical performance technical and tactical skills, psychological and club characteristics of male soccer players aged 12 to 14 years. A total of 157 male soccer players clustered into three age-cohorts (12, 13 and 14 years) were recruited from six soccer clubs. Anthropometric, body composition and body physique, biological maturation, physical performance, skill/game proficiency data, psychological characteristics, and clubs’ characteristics were collected. Group means were compared using analysis of variance and covariance. Fourteen years old players were significantly taller, heavier, leaner, faster, stronger, and technically more skilled than their younger peers (p &lt, 0.05). Differences in physical performance and technical skills (p &lt, 0.05) were found between age groups when adjusting for confounders of soccer training and biological maturation. No significant differences (p &gt, 0.05) between age groups were found in psychological domains. Our findings suggest that age, biological maturation, and training volume are key factors influencing young soccer players’ performance and development. Further, clubs’ conditions provide players with ample resources for their success in training and competition.

Several talent identification programs in elementary school have implemented motor diagnostics to introduce children to groups of sports, like game sports, or even to particular sports like soccer. However, as in most other sports, in youth soccer, the predictive value of such early testing is still unclear. This prospective study evaluated the midterm prognostic validity of generic motor performance tests. The sample consisted of male second-grade children, which had received a recommendation to participate in soccer. The talent screening campaign was a basic check comprising two anthropometric parameters, five physical fitness, and three motor competence diagnostics of the German Motor Test 6–18. The test data were collected from the participating elementary school classes of the years 2010 to 2014. The soccer competition performance of those children having completed the age of at least 15 years (n = 502) up to the end of the season 2019/2020 (2020, September 30) was recorded. This group of U17 players was then assigned individually to five different competition levels. The prognostic validity of the physical and physiological tests was determined using ANOVAs, odds ratios, and a regression path analysis. All diagnostic methods exhibited medium-to-high prognostic validity over the 8 year time span from the talent screening to the later soccer competitions in the adolescent age groups. For later success in soccer on the province level, the 6-min run (OR = 4.28), dynamic balance (OR = 4.04), and 20-m sprint (OR = 2.46), as well as the participation in the training center of the German Soccer Federation (OR = 5.67) and the diversity of club sport activities (OR = 3.56), were of particular importance.

Ramirez-Campillo, R, Alvarez, C, Gentil, P, Loturco, I, Sanchez-Sanchez, J, Izquierdo, M, Moran, J, Nakamura, FY, Chaabene, H, and Granacher, U. Sequencing effects of plyometric training applied before or after regular soccer training on measures of physical fitness in young players. J Strength Cond Res 34(7): 1959-1966, 2020-To compare the effects of short-term (i.e., 7 weeks) plyometric jump training applied before (PJT-B) or after (PJT-A) soccer practice on components of physical fitness in young soccer players, a single-blind randomized controlled trial was conducted. Postpubertal boys aged 17.0 ± 0.5 years were allocated to 3 groups: PJT-B (n = 12), PJT-A (n = 14), and control (CON; n = 12). The outcome measures included tests to evaluate 20-m speed, standing long jump (SLJ), squat jump (SJ), countermovement jump (CMJ), and drop jump (DJ), 20-m multistage shuttle run endurance (MSSRT), and Illinois change-of-direction speed (ICODT). Although the CON performed soccer-specific training, the PJT-A and PJT-B groups conducted the same soccer-specific sessions but replaced ∼11% of their time with plyometric training. The PJT-B group performed plyometric exercises after a warm-up program, and the PJT-A group conducted plyometric exercises ∼10 minutes after the completion of soccer training. Analyses of variance were used to detect differences between groups in all variables for pretraining and posttraining tests. Main effects of time (all p < 0.01; d = 0.19-0.79) and group × time interactions (all p ≤ 0.05; d = 0.17-0.76) were observed for all examined variables. Post hoc analyses revealed significant increases in the PJT-B group (SLJ: 9.4%, d = 1.7; CMJ: 11.2%, d = 0.75; 20-m MSSRT: 9.0%, d = 0.77) and the PJT-A group (SLJ: 3.1%, d = 0.7; CMJ: 4.9%, d = 0.27; 20-m MSSRT: 9.0%, d = 0.76). Post hoc analyses also revealed significant increases in the PJT-B group (20-m speed: -7.4%, d = 0.75; 20-cm DJ reactive strength index: 19.1%, d = 1.4; SJ: 6.3%, d = 0.44; ICODT results: -4.2%, d = 1.1). In general, our study revealed that plyometric training is effective in improving measures of physical fitness in young male soccer players when combined with regular soccer training. More specifically, larger training-induced effects on physical fitness were registered if plyometric training was conducted before soccer-specific training.

El fútbol es el deporte más practicado a nivel mundial. Esta popularidad se debe a que prácticamente cualquier persona lo puede jugar de manera amateur, pero a medida que se va profesionalizando se requiere la valoración de un perfil antropométrico que favorezca un rol determinado dentro del campo de juego. El objetivo del estudio fue comparar las características antropométricas de futbolistas chilenos juveniles sub 14, sub 15 y sub 16 de acuerdo con la posición de juego y la categoría. Se evaluaron a 180 futbolistas juveniles de sexo masculino con edades entre los 13 y 16 años, pertenecientes a las divisiones inferiores de los clubes: Audax Italiano, Cobresal y Magallanes de la Región Metropolitana de Chile. Los datos se consideraron estadísticamente significativos con p < .05. Se encontraron diferencias significativas en el peso, talla, sumatoria de 6 pliegues, kilogramos de piel, grasa, masa ósea, masa residual y en todas las longitudes corporales entre jugadores de distintas posiciones de juego. Asimismo, se encontraron diferencias estadísticas en el peso, talla, kilogramos de piel, grasa, masa ósea, músculo, masa residual y en todas las longitudes corporales menos en la radial-estiloidea entre jugadores de distintas categorías. Los resultados muestran la importancia de dividir a los futbolistas juveniles en un mayor número de roles posicionales al momento de definir las características antropométricas ideales según su ubicación en el terreno de juego. Las diferencias encontradas en la composición corporal entre categorías sugieren prestar atención al desarrollo madurativo al momento de promover a algún jugador a una división mayor. Soccer is the most practiced sport in the world. This popularity is since practically anyone can play it amateurishly, but as it becomes professionalized it requires the valuation of ananthropometric profile that favors a certain role within the playing field. The objective of the study was to compare the anthropometric characteristics of Chilean youth soccer players sub 14, sub 15 and sub 16 according to the game position and category. The number of individuals evaluated in this study was 180 male youth players in the sub 14 categories (n = 60), sub 15 (n = 58) and sub 16 (n = 62), belonging to the lower divisions of the soccer clubs: Audax Italiano (n = 62), Cobresal (n = 57) and Magallanes (n =61) from the Metropolitan Region. The sample was chosen for convenience and consists of the total of players belonging to these three categories and these three soccer teams. These players had an average training of 4 days a week with a duration of each practice session of 120 minutes, plus a match on weekends with a duration of 90 minutes. There were significant differences in all of them between different game positions. We can emphasize that the central defenses presented the greatest statistical differences in all the lengths corresponding to the lower limbs: iliospinal height (97.6 ± 3.6), trochanteric height (92.1 ± 3.3), trochanteric-tibial lateral length (45.2 ± 1.7), lateral tibial height (46.3 ± 1.8) and medial-malleolar medial tibial length (38.7 ± 2.0), whereas the archers had them in the lengths of the train superior: acromio-radial (33.0 ± 1.6), radial-styloid (27.8 ± 1.7) and styloid-dactyly medium (20.2 ± 1.0). It was also found that there are significant differences in weight among players of different categories, with those of sub 16 having the highest weight (65.7 ± 7.4) and those of sub 14 the lowest (58.7 ± 8.1). At the same time, it is shown how there are statistical differences in the size between the sub 14 division who obtained the lowest measurement on average and the other 2 series confronted, but not so between sub 15 and sub 16, the latter being those who had the highest stature on average. It is also shown as the percentage of fat mass, ranging between 24.2 % of the sub 15 division in its lower limit, and 25.2% of the sub 14 in its upper limit being all considered as "acceptable" and without statistical significance between any categories. Statistical differences were found between the sub 14 category and the sub 16 category in all body lengths except in the radial-styloid. It is also shown that there are significant differences between the sub 14 and sub 15 in the lengths: acromio-radial and trochanteric-lateral tibial and in the heights: ilio-spinal, trochanteric and lateral tibial. This is directly related to the lower average stature they present in the sub-division 14. In turn, no statistical significance was found at any length between sub-15 and sub-16 players. Likewise, statistical differences were found in the weight, height, and weight of: skin, fat, bone mass, muscle, residual mass and in all body lengths less than radial-styloid among players of different categories. The results show the importance of dividing the young players in a greater number of positional roles when defining the ideal anthropometric characteristics according to their location in the field of play. The differences found in the body composition between categories suggest paying attention to the development of maturity when promoting a player to a larger division.

This research is aimed at examining sensitivity of the speed evaluation tests while carrying the ball. The research included 76 male examinees, aged 17 years (+/- 6 months), who were divided into two qualitatively different subgroups. For determining the speed while carrying the ball, the tests of M type of carrying the ball between cones and slalom ball carrying with a pass were performed. The obtained results proved that the examinees from the group of more successful soccer players (Group 1) scored better on the applied tests when compared to the results of the group consisting of the soccer players from lower ranked clubs and who are not national team members (Group 2). High values of the result homogeneity in the two groups (for the Groups 1 and 2 it was 75% and 68.75% respectively) lead to the conclusion that this ability is essential characteristics of young soccer players. The coefficient of discrimination of 0.269 for the results of M type test and 0.197 for the results of the test of carrying the ball with a pass indicate that the results of the two tests provide possibility to qualitatively distinguish youth players. Therefore, it can be concluded that as a technical element, carrying the ball significantly affects the quality of players' performance.

Background Soccer is a high-intensity sport with a high injury rate. Among youth soccer players, lower extremity pain is a major problem that could be associated with trunk function. This study investigated the association between lower extremity pain and trunk pain among youth soccer players. Methods A cross-sectional study involving youth soccer players participating in the Miyagi Amateur Sports Association was conducted using a self-reported questionnaire. A multiple logistic regression analysis was used to examine the association between trunk pain and lower extremity pain. Covariates were sex, age, body mass index, height increase, number of days of training per week, practice time per day on weekdays or weekends, competition levels, frequency of participation in games, and previous injuries. Results The final study population comprised 1139 youth soccer players (age, 6–15 years; male, 94.2%). Lower extremity pain with concomitant trunk pain occurred in 61.8% (42/68). Trunk pain was significantly associated with lower extremity pain (adjusted odds ratio [OR], 6.82; 95% confidence interval [CI], 3.99–11.67). Back pain and hip pain were significantly associated with knee pain (adjusted OR [95% CI]: 7.63 [3.70–15.76] and 3.84 [1.89–7.83], respectively), ankle pain (adjusted OR [95% CI]: 9.03 [4.42–18.44] and 5.43 [2.77–10.62], respectively), and both knee and ankle pain (adjusted OR [95% CI]: 13.67 [6.01–31.09] and 5.98 [2.56–13.97], respectively). Conclusions Trunk pain was associated with lower extremity pain among youth soccer players. Clinicians and coaches should consider comorbidities while treating those players.

nderstanding the contribution of the energy systems in soccer has involved the use of time-motion studies. A number of tools have bein used (e.g., pen and paper methods, video, electronic tracking devices). Recently, global positioning technology (GPS) has been shown to be the most accurate tracking system. -In order to correctly determine the physiological requirements of football and the dosing of the workload, it is necissary to quantiff ii during an ofdcial match. [7, 8, 18] This is done by measuring different types of mobility, known as time-motion analysis. This analysis is widespread in all team sports as the most intensive use has been made in the last two decades [1, 8].

El objetivo fue determinar el perfil bioquimico de los equipos juveniles de futbol nacional y comparar los valores de nueve parametros bioquimicos entre tres equipos nacionales serbios (menores de 14, 15 y 16 anos de edad), asi como entre los jugadores de futbol y no atletas. Ochenta jovenes jugadores de futbol y treinta no atletas participaron en el estudio. Se midieron nueve parametros bioquimicos (glucosa, colesterol, trigliceridos, urea, creatinina, bilirrubina total, AST (SGOT), ALT (SGPT), hierro). Con el fin de determinar la significacion de las diferencias entre los grupos en un nivel multivariado se administro un analisis multivariado de varianza (MANOVA), y para poner a prueba las diferencias entre los grupos en un nivel univariado se aplico un analisis univariado de la varianza (ANOVA). Se encontraron diferencias estadisticamente significativas entre los grupos (jugadores de futbol hasta 14, 15 y 16 anos de edad) en un nivel multivariado de las variables bioquimicas (MANOVA, p= 0,00). ANOVA tambien revelo diferencias significativas en creatina (p= 0,00), la bilirrubina total (p= 0,00) y ALT (SGPT) (p= 0,02). Se encontraron diferencias estadisticamente significativas en las variables aplicadas entre los jugadores de futbol y no atletas a nivel multivariado (MANOVA p= 0,00). ANOVA tambien revelo diferencias significativas en glucosa, colesterol, trigliceridos, creatinina, bilirrubina total, ALT (SGPT) y hierro (p= 0,00) entre los jugadores de futbol y no atletas. Sin embargo no hubo diferencias estadisticamente significativas en otras variables (AST (SGOT) y urea). Se concluyo que a excepcion de la AST (SGOT) y urea no existe diferencia significativa en casi todas las variables (glucosa, colesterol, trigliceridos, etc.) entre los jugadores de futbol y no atletas. Desde un punto de vista practico, el medico debe tener en cuenta no solamente la edad, sino tambien la formacion de estado de los individuos en la evaluacion de sus analisis de sangre.

The aim of this study was to examine the influence of hormonal status, anthropometric profile, sexual maturity level, and physical performance on the technical abilities of 40 young male soccer players during small-sided games (SSGs). Anthropometric profiling, saliva sampling, sexual maturity assessment (Tanner scale), and physical performance tests (Yo-Yo and vertical jumps) were conducted two weeks prior to the SSGs. Salivary testosterone was determined by the enzyme-linked immunosorbent assay method. Technical performance was determined by the frequency of actions during SSGs. Principal component analyses identified four technical actions of importance: total number of passes, effectiveness, goal attempts, and total tackles. A multivariate canonical correlation analysis was then employed to verify the prediction of a multiple dependent variables set (composed of four technical actions) from an independent set of variables, composed of testosterone concentration, stage of pubic hair and genitalia development, vertical jumps and Yo-Yo performance. A moderate-to-large relationship between the technical performance set and the independent set was observed. The canonical correlation was 0.75 with a canonical R2 of 0.45. The highest structure coefficient in the technical performance set was observed for tackles (0.77), while testosterone presented the highest structure coefficient (0.75) for the variables of the independent set. The current data suggest that the selected independent set of variables might be useful in predicting SSG performance in young soccer players. Coaches should be aware that physical development plays a key role in technical performance to avoid decision-making mistakes during the selection of young players.

The purpose of this study was to compare the effects of Small-Sided Games (SSG) vs. Interval Training (IT) in soccer training on aerobic fitness and physical enjoyment in youth elite soccer players during the last 8 weeks of the season. Seventeen U-16 male soccer players (age = 15.5 +/- 0.6 years, and 8.5 years of experience) of a Spanish First Division club academy were randomized to 2 different groups for 6 weeks: SSG group (n = 9) and IT group (n = 8). In addition to the usual technical and tactical sessions and competitive games, the SSG group performed 11 sessions with different SSGs, whereas the IT group performed the same number of sessions of IT. Players were tested before and after the 6-week training intervention with a continuous maximal multistage running field test and the counter movement jump test (CMJ). At the end of the study, players answered the physical activity enjoyment scale (PACES). During the study, heart rate (HR) and session perceived effort (sRPE) were assessed. SSGs were as effective as IT in maintaining the aerobic fitness in elite young soccer players during the last weeks of the season. Players in the SSG group declared a greater physical enjoyment than IT (P = 0.006; ES = 1.86 +/- 1.07). Coaches could use SSG training during the last weeks of the season as an option without fear of losing aerobic fitness while promoting high physical enjoyment.

314 p., The aim of the present study was to determine anthropometric, physical and physiological characteristics of high level players, to analyze how these parameters change across time and to determine their relevance in the selection process of a professional soccer club. The study involves a longitudinal analysis during 4 competitive seasons of young soccer players of the Athletic Club of Bilbao that were evaluated annually on two occasions. Anthropometry, physical performance tests, salivary hormones concentration, chronological age and age at peak height velocity were measured. We observed that as players get older they grew and performed better. However, results indicate that changes in performance were significantly affected by growth and maturation. Thus, the patterns of physical growth and maturation of young players merit more detailed consideration. Besides, it seems clear that a large body size and a small amount of body fat are relevant anthropometric parameters involved in the selection process of high level soccer players. Moreover, we observed that anthropometrical and physical performance characteristics can differentiate between players that are selected from those that are not. Also, results demonstrate that these procedures may eliminate late maturer’s with potential and exclude players born late. Finally, it seems that technical staff of the club selects players with a large body size, advanced maturity, and particularly older chronological age and less body fat.

314 p. The aim of the present study was to determine anthropometric, physical and physiological characteristics of high level players, to analyze how these parameters change across time and to determine their relevance in the selection process of a professional soccer club. The study involves a longitudinal analysis during 4 competitive seasons of young soccer players of the Athletic Club of Bilbao that were evaluated annually on two occasions. Anthropometry, physical performance tests, salivary hormones concentration, chronological age and age at peak height velocity were measured. We observed that as players get older they grew and performed better. However, results indicate that changes in performance were significantly affected by growth and maturation. Thus, the patterns of physical growth and maturation of young players merit more detailed consideration. Besides, it seems clear that a large body size and a small amount of body fat are relevant anthropometric parameters involved in the selection process of high level soccer players. Moreover, we observed that anthropometrical and physical performance characteristics can differentiate between players that are selected from those that are not. Also, results demonstrate that these procedures may eliminate late maturer’s with potential and exclude players born late. Finally, it seems that technical staff of the club selects players with a large body size, advanced maturity, and particularly older chronological age and less body fat. La autora del trabajo recibió una beca predoctoral del Gobierno Vasco (BFI2010-35)

Background. The importance of aerobic performance in youth soccer is well established. The aim of the present study was to evaluate the contributions of chronological age (CA), skeletal age (SA), body size, and training to the longitudinal development of aerobic performance in youth male soccer players aged 10 to 18 years. Material and Methods. Players (n=83) were annually followed up during 5 years, resulting in an average of 4.4 observations per player. Decimal CA was calculated, and SA, stature, body weight, and aerobic performance were measured once per year. Fat-free mass (FFM) was estimated from age- and gender-specific anthropometric formulas, and annual volume training was recorded. After testing for multicollinearity, multilevel regression modeling was used to analyze the longitudinal data aligned by CA and SA (Model 1 and 2, respectively) and to develop aerobic performance scores. Results. The following equations provide estimations of the aerobic performance for young soccer players: ŷ(Model 1 [deviance from the null model =388.50; P