The presence of the relative age effect (RAE) has been widely reported; however, its underlying causes have not yet been determined. With this in mind, the present study examined if anthropometry and performance were different amongst older and younger soccer players born in the same year. Eighty-eight young soccer players participated in the study (age 9.75 ± 0.30). Anthropometric measurements, physical tests (sprint, agility, endurance test, jump and hand dynamometry) and the estimation of the maturity status were carried out. Most players (65.9%) were born in the first half of the year. Older players were taller (P < 0.05), had longer legs (P < 0.01) and a larger fat-free mass (P < 0.05). Maturity offset was smaller in the older boys (P < 0.05); however, age at peak height velocity was similar. Older boys performed better in velocity and agility (P < 0.05) and particularly in the overall score of performance (P < 0.01). Stepwise regression analysis revealed that chronological age was the most important variable in the agility test and the overall score, after the skinfolds (negative effect). We report differences in anthropometry and physical performance amongst older and younger pre-pubertal soccer players. These differences may underlie the RAE.

The aims of the present study were, firstly, to determine the reliability and reproducibility of an agility T-test and Yo-Yo 10 m recovery test; and secondly, to analyse the physical characteristics measured by sprint, agility, strength and endurance field tests in wheelchair basketball (WB) players. 16 WB players (33.06 ± 7.36 years, 71.89 ± 21.71 kg and sitting body height 86.07 ± 6.82 cm) belonging to the national WB league participated in this study. Wheelchair sprint (5 and 20 m without ball, and 5 and 20 m with ball) agility (T-test and pick-up test) strength (handgrip and maximal pass) and endurance (Yo-Yo 10 m recovery test) were performed. T-test and Yo-Yo 10 m recovery test showed good reproducibility values (intraclass correlation coefficient, ICC = 0.74-0.94). The WB players’ results in 5 and 20 m sprints without a ball were 1.87 ± 0.21 s and 5.70 ± 0.43 s and with a ball 2.10 ± 0.30 s and 6.59 ± 0.61 s, being better than those reported in the literature. Regarding the pick-up test results (16.05 ± 0.52 s) and maximal pass (8.39 ± 1.77 m), players showed worse values than those obtained in elite players. The main contribution of the present study is the characterization of the physical performance profile of WB players using a field test battery. Furthermore, we demonstrated that the agility T-test and the aerobic Yo-Yo 10 m recovery test are reliable; consequently they may be appropriate instruments for measuring physical fitness in WB.

BackgroundSoccer is a form of exercise that induces inflammatory response, as well as an increase in free radicals potentially leading to muscle injury. Balanced nutritional intake provides important antioxidant vitamins, including vitamins A, C and E, which may assist in preventing exercise-related muscle damage. The purpose of the present study was to determine the effect of macro/micronutrient intake on markers of oxidative stress, muscle damage, inflammatory and immune response in female soccer players.MethodsTwenty-eight female players belonging to two soccer teams of the same professional soccer club participated in this study after being informed about the aims and procedures and after delivering written consent. Each team completed an 8-day dietary record and played one competition match the same week. Participants were divided into two groups: the REC group (who complied with recommended intakes) and the NO-REC group (who were not compliant). Laboratory blood tests were carried out to determine hematological, electrolytic and hormonal variables, as well as to monitor markers of cell damage and oxidative stress. Blood samples were obtained 24 h before, immediately after and 18 h after official soccer matches. Student t-test or Mann–Whitney U-test was used to compare both groups throughout the match.ResultsAt rest, we observed that the REC group had higher levels of total antioxidant status (TAS), glutathione peroxidase (GPx), and lower levels of creatine kinase (CK) and lactate dehydrogenase (LDH) in comparison to the NO-REC group. Immediately after the match, levels of TAS, GPx, superoxide dismutase (SOD), LDH and % lymphocytes were higher and the % of neutrophils were lower in the REC group compared to the NO-REC group. These differences were also maintained 18 h post-match, only for TAS and GPx.ConclusionsOur data reveal an association between nutritional intake and muscle damage, oxidative stress, immunity and inflammation markers. The benefit of the intake of specific nutrients may contribute to preventing the undesirable physiological effects provoked by soccer matches.

The aim of this study was to analyse the talent identification process of a professional soccer club. A preselection of players (n = 64) aged 9-10 years and a final selection (n = 21) were performed by the technical staff through the observation during training sessions and matches. Also, 34 age-matched players of an open soccer camp (CampP) acted as controls. All participants underwent anthropometric, maturity and performance measurements. Preselected outfield players (OFs) were older and leaner than CampP (P < 0.05). Besides, they performed better in velocity, agility, endurance and jump tests (P < 0.05). A discriminant analysis showed that velocity and agility were the most important parameters. Finally, selected OFs were older and displayed better agility and endurance compared to the nonselected OFs (P < 0.05). Goalkeepers (GKs) were taller and heavier and had more body fat than OFs; also, they performed worse in the physical tests (P < 0.05). Finally, selected GKs were older and taller, had a higher predicted height and advanced maturity and performed better in the handgrip (dynamometry) and jump tests (P < 0.05). Thus, the technical staff selected OFs with a particular anthropometry and best performance, particularly agility and endurance, while GKs had a different profile. Moreover, chronological age had an important role in the whole selection process.

Wheelchair basketball players are classified in four classes based on the International Wheelchair Basketball Federation (IWBF) system of competition. Thus, the aim of the study was to ascertain if the IWBF classification, the type of injury and the wheelchair experience were related to different performance field-based tests. Thirteen basketball players undertook anthropometric measurements and performance tests (hand dynamometry, 5 m and 20 m sprints, 5 m and 20 m sprints with a ball, a T-test, a Pick-up test, a modified 10 m Yo-Yo intermittent recovery test, a maximal pass and a medicine ball throw). The IWBF class was correlated (p<0.05) to the hand dynamometry (r= 0.84), the maximal pass (r=0.67) and the medicine ball throw (r= 0.67). Whereas the years of dependence on the wheelchair were correlated to the velocity (p<0.01): 5 m (r= −0.80) and 20 m (r= −0.77) and agility tests (r= −0.77, p<0.01). Also, the 20 m sprint with a ball (r= 0.68) and the T-test (r= −0.57) correlated (p<0.05) with the experience in playing wheelchair basketball. Therefore, in this team the correlations of the performance variables differed when they were related to the disability class, the years of dependence on the wheelchair and the experience in playing wheelchair basketball. These results should be taken into account by the technical staff and coaches of the teams when assessing performance of wheelchair basketball players.

This study investigated whether anthropometric characteristics, generic and specific sprinting, agility, strength, and endurance capacity could differentiate between First-Division and Third-Division wheelchair basketball (WB) players. A First-Division WB team (n = 8; age = 36.05 ± 8.25 years, sitting body height = 91.38 ± 4.24 cm, body mass = 79.80 ± 12.63 kg) and a Third-Division WB team (n = 11; age = 31.10 ± 6.37 years, sitting body height = 85.56 ± 6.48 cm, body mass = 71.18 ± 17.63 kg) participated in the study. Wheelchair sprint, agility, strength, and endurance tests were performed. The First-Division team was faster (8.7%) in 20 m without the ball, more agile (13-22%), stronger (18-33%), covered more distance (20%) in the endurance test, and presented higher values of rate of perceived exertion for the exercise load (48%) than the Third-Division team. Moreover, the individual 20-m sprint time values correlated inversely with the individual strength/power values (from r = -0.54 to -0.77, p ≤ 0.05, n = 19). Wheelchair basketball coaches should structure strength and conditioning training to improve sprint and agility and evaluate players accordingly, so that they can receive appropriate training stimuli to match the physiological demands of their competitive level.

Introduction: in soccer, agility is a relevant parameter that is defined as the ability to change the direction of the body rapidly and is a result of a combination of strength, speed, balance and coordination. Objective: to demonstrated the reliability and validity of the modified Barrow test in soccer players aged 10 to 14 years, analyze its relationship with age, maturation, experience and body size and test the effectiveness of the protocol for distinguishing performance changes during a 10-month competitive season. Methods: fifty-one adolescent Basque soccer players were enrolled. Age, maturation, experience, body size, vertical jump and 15-m sprint were measured. The reliability of the test was analyzed using replicate tests in a subgroup (n = 34). Another subgroup of 33 players (n =18, under-11, 10.4 ± 0.3 years; n = 15 under-13, 12.0 ± 0.8 years) was evaluated at the beginning and the end of the season. Results: the reliability of the test was good (change in mean = -0.5%, 95% CI -1.2 to 0.2, SD=0.14; coefficient of variation = 0.9%, 95% CI -0.7 to 1.5, SD=0.25). Chronological age and adiposity were significant predictors of agility performance (P<0.01). An improvement in performance was observed over a 10-month soccer season, with a significant group effect (P<0.01). Conclusion: the agility test demonstrated logic and validity, and proved to be a reliable and objective instrument for assessing adolescent soccer players.

El efecto relativo de la edad (RAE) ha sido ampliamente estudiado en futbol revelando una distribución de nacimientos sesgada que favorece a los jugadores nacidos en los primeros meses del año. También, se ha observado que el efecto es más relevante en los equipos de alto nivel. Con esto en mente, este estudio analiza el predominio del efecto relativo de la edad en diferentes equipos de un club de futbol profesional así como en los procesos de selección de este. Considerando todo el equipo, la distribución difiere significantemente de la distribución teórica esperada (p<.05). Se encontraron diferencias significativas entre los nacimientos observados y los esperados en las categorías alevines (masculino, x2 = 8.14, p<.05; femenino, x2 = 11.5, p<.01). Además, en la categoría femenina no hubo ninguna jugadora nacida entre septiembre y diciembre del año de selección. Sin embargo, no se encontraron diferencias significativas entre los resultados esperados y observados en categorías superiores a pesar de observarse una distribución sesgada. En conjunto, hubo una sobrerrepresentación de jugadores nacidos en los primeros meses del año en todo el equipo confirmando la presencia del RAE en el club. Por otra parte, al analizar el efecto en los procesos de selección confirmamos que este comenzaba antes de que los jugadores ingresasen en el club. Se observaron diferencias significativas en todas las fases de selección entre los jugadores seleccionados y no seleccionados (x2 = 18.10-7.80, p<.05). En consecuencia, podemos decir que el RAE comienza en la identificación temprana de los jugadores. Palabras clave: Fecha de nacimiento, RAE, fútbol, club profesional.Abstract: The presence of RAE has been widely reported and studied in soccer revealing skewed birth-date distributions favoring individuals born early in the selection year. Indeed, it has been documented that RAE is more relevant in high level teams. With this in mind, the present study examined the prevalence of the Relative Age Effect (RAE) in different age groups of a professional soccer club and in the selection processes of the same club. Considering the entire club, distribution differs significantly from the theoretical distribution expected (p<.05). Regarding different categories, there were significant differences between the observed and expected births in both alevin categories (male, x2 = 8.14, p<.05; female, x2 = 11.5, p<.01). Moreover, in womens alevin age group none of the players was born between September and December of the selection year. Nevertheless, they were not significant differences between the expected and observed results in higher categories but a comparatively biased distribution was observed. Overall, we found an over-representation of players born at the beginning of the year confirming the presence of the RAE in the club. When analyzing the effect of RAE in the talent identification process we observed that it begins before the players enter the club. Comparing the distributions of the not-selected players against the selected players significant differences were found in each of the selection phases (x2 = 18.10-7.80, p<.05). Thus, results revealed that the relative age effect acts in the early identification process of the players.Keywords: Birth date, RAE, soccer, professional club.