The associations of early specialization, sports volume, and maturity status with musculoskeletal injury in elite youth football players.

Background: Youth football in schools has experienced rapid growth in China. Despite the increase of players engaging in more frequent, intensive, and organized sports training at their early ages, the controversy over early specialization (ES) still exists. This study aims to: a) investigate the training situation of players in the Chinese School Football Programme and b) examine the associations of early specialization, sports volume, and maturity status with musculoskeletal injury. Methods: A cross-sectional survey was used. Players who participated in the National School Football Winter Camp were invited to fill out a questionnaire that included the data of maturity, ES, sports volume, and injury history (n = 88 boys and n = 90 girls). Results: The results have shown that 80.3% of the athletes were classified as ES, while 19.7% of them were classified as non-ES. Almost all athletes (96%) participated in a sport for more than 8 months in a year. Most athletes (75.8%) spent more than twice of the time on organized sports than leisure activities. 30.3% of the athletes trained on average more hours per week than the number of their ages. Binomial logistic regression models reflected the significant differences in the odds ratios (OR) of reporting a history of injury among athletes with different levels of specialization (p = 0.024) and the OR of reporting a history of leg injury among players with different weekly sports volumes (p = 0.038). Significant differences were also shown in the OR of players reporting foot injuries between players with different maturity states (p = 0.046), and the Chi-squared test showed significant differences in the OR of reporting acute injuries between players with different levels of specialization (p = 0.048) and weekly activity (p = 0.022). No significant differences were found between the remaining variables. Conclusion: Most school football elite players follow the ES pathway even though ES increases the risk of injury, especially acute injury. Pre-pubertal and early pubertal players have a higher incidence of foot injuries. Players who train more hours per week than their ages have more leg injuries and acute injuries. Therefore, priority protection and intervention should be carried out for populations with a high risk of injury.

What Is the Most Sensitive Test to Identify Fatigue through the Analysis of Neuromuscular Status in Male Elite Futsal Players?

The present study aimed to determine which of the neuromuscular status (NMS) monitoring tests (1: Counter-movement jump, CMJ; 2: back squat with additional load) is the most sensitive and effective for evaluating the state of fatigue in futsal players during the preseason. Seventeen professional futsal players were recruited for this study (age: 23.07 ± 6.76 years; height: 1.75 ± 0.06 m; body mass: 75.47 ± 7.47 kg; playing experience in elite: 5.38 ± 2.03 years). All of them were evaluated during the preseason phase in two tests (CMJ and back squat with additional load) before and after each training session (pre- vs. post-test). A jump platform was used to extract jump height during CMJ, while a linear position transducer was used to extract mean velocity (MV) and mean propulsive velocity (MPV) during the back squat exercise. Significant differences were obtained for intra-subject analysis for MV and MPV in loaded back squat exercise (p < 0.001), finding lower values during the post-test. In conclusion, the monitoring of NMS through the back squat provides greater sensitivity and objectivity in comparison with CMJ, due to a more direct neuromuscular extrapolation to the physical demands of futsal.

Students' Physical Activity Profiles According to Children's Age and Parental Educational Level.

The aim of this study was to identify different profiles of physical activity (PA) behaviors according to the school student's age stage and their parents' or guardians education level. Seven hundred twenty-seven students and parents of different educational stages were invited to take part in this study. The participants included, Preschool (1 to 5 years old), Primary School (6 to 11 years old), Secondary School (12 to 15 years old), and High School (16 to 18 years old). A questionnaire to assess the educational level of parents (low, intermediate, and high) and their child's PA level and sedentary behaviors across various age stages was administered. The results showed a number of different physical activity profiles for preschool (4), primary (6), secondary (7) and high school (2) students. Primary and secondary school children's behavioral profiles were reported to differ significantly between both physical activity levels and sedentary behaviors, while preschool students' behavioral profiles only differed between sedentary behaviors. Higher parental education was most prevalent in clusters with significantly higher levels of PA in primary and secondary students, while there were equivocal trends for parental education level influencing behavioral profiles of high school students. These findings suggest there is some association between the behavioral profiles of student's physical activity and sedentary behavior, and parental education level, most noticeably during the early to middle age stages.

In Search for Volleyball Entertainment: Impact of New Game Rules on Score and Time-Related Variables.

The aim of this research was to analyse the impact of various game structures on score and time-related variables in elite volleyball. A total of 114 male matches and 76 female matches (38 matches for each tournament) were analysed in under-23 world championships. An observational design was implemented to measure match duration, points scored per match and set, set point differences, tournament phase, match balance, and set tendencies in various game structures (set to 21, to 25 or to 15 points) in male and female categories. Standardised differences in mean values showed that a 15-point set game structure led to shortest matches and smallest time variability in match duration, the largest number of points per match, and greatest equality in terms of set score differences in both the male and the female category. The use of various game structures in training may be useful to coaches and conditioning specialists when planning training schemes and sessions, by introducing different game structures to manage volume and intensity in training more effectively. These results may also be useful to local and/or national volleyball federations willing to attract new young players, to promote learning and to render volleyball a fun activity, by implementing S15 at initial stages. In addition, they could be useful to international federations or committees, so as to attract larger audiences and sponsors interested in more appealing matches with high levels of competitiveness and entertainment.

Validación herramienta observacional para el análisis de rachas de lanzamiento en baloncesto / Validation of an observation al instrument for shooting streaks in basketball

El objetivo de esta investigación fue diseñar y validar una herramienta de observación ad-hoc para el análisis de las rachas de lanzamiento en el baloncesto profesional. Para dicho proceso de validación se han desarrollado 5 fases: Fase 1) Identificación, selección y categorización de posibles variables a incluir en la herramienta; Fase 2) Realización de una observación piloto para afinar o incluir nuevas variables; Fase 3) Calculo V de Aiken para analizar la validez de contenido mediante criterio experto; Fase 4) Calculo de validez interna del instrumento criterio de entrenadores superiores; Fase 5) Análisis de la validez intra-observador e inter-observador mediante el índice de correlación de Pearson, coeficiente de correlación intraclase e índice Kappa de Cohen. Podemos afirmar que el instrumento diseñado es válido y fiable para el análisis de las rachas de lanzamiento en el baloncesto profesional masculino (AU)

The purpose of this research is to design and validate an ad-hoc observational instrument to analyze shooting streaks in professional basketball. The instrument and its validation was developed in five steps. In the first step a preliminary list of candidates variables was made. In the second step a pilot observation was done to refine or include new variables. In the third and fourth steps the content validity was established and calculated by means of the Aiken’s V method respectively. In the fifth step inter and intra observer reliability were tested by using the Pearson’s correlation coefficient, the intraclass correlation coefficient and the Cohen’s Kappa coefficient. The instrument designed has been proved to be valid and reliable for the analysis of shooting streaks in men’s professional basketball (AU)

Las preferencias participativas del profesorado de educación física en su actividad profesional / The physical education teachers’ participative preferences in their professional activit

Los entornos colaborativos han sido promocionados como la mejor solución a los problemas que la actividad docente puede presentar independientemente de las preferencias personales de los profesores. El objetivo del estudio es desarrollar una escala de preferencias de interacción social en el entorno laboral para los profesores de educación física, partiendo de la Escala GR de Ruiz et al. (2010), así como evaluar su equivalencia de medida en profesores con diferentes años de experiencia docente y entre hombres y mujeres, utilizando el análisis factorial confirmatorio multigrupo. En este estudio participaron 1413 profesores españoles. La escala final quedó constituida por las 4 cuatro dimensiones originarias: Cooperación, Competición, Individualismo y Afiliación que explicaron un 66.43% de la varianza y presentaron valores elevados de consistencia interna. Por otro lado, los resultados indican una equivalencia factorial estricta. Los profesores con más años de experiencia prefieren escenarios de trabajo más individualistas y cooperativos que aquellos con menor experiencia y los hombres tienen preferencias más individualistas y competitivas, mientras que las mujeres tienen mayor orientación cooperativa

Nowadays the collaborative learning environments have been promoted by the physical education teachers as the best way for decreasing teaching problems independently of teachers’ personal achievements. The aim of the present study was to develop a scale for physical education teachers about social interactions preferences in the workplace environment. Based on the scale GR developed by Ruiz et al. (2010), the multisample confirmatory factor analysis was used to assess the equivalence measure between years of experience and gender. The participants were 1413 Spanish physical education teachers. The final scale was composed of the 4 initial dimensions: cooperation, competition, individualization, and affiliation. The four dimensions accounted for 66.43% of the total variance, and showed high values of internal consistency. Also, the results pointed out a strict factorial invariance. Finally, the results showed that the more experienced teachers prefer individualized and competitive workplace environments than the less experienced ones, and on the other hand, men’s teachers were more individualistic and competitive compared with women’s teachers whom prefer cooperative orientations in the workplace environment

Do faster swimmers spend longer underwater than slower swimmers at World Championships?

The main objectives of the present research were (1) to examine the relationships between the distances travelled underwater during the start and turn segments with swimming race performance at the elite level and (2) to determine if the individualised-distance start and turn parameters affect the overall race performance. The race parameters of the 100 and 200 m events during 2013 World Championships were measured by an innovative image-processing system (InThePool(®) 2.0). Overall, 100 m race times were largely related to faster start velocities in men's breaststroke and freestyle events. Conversely, overall, 200 m race times were largely related to longer starting distances in the women's butterfly events, to longer turn distances in men's and women's backstroke and women's butterfly events and to shorter turn distances in women's freestyle events. Changes on the start or turn velocities could represent moderate time improvements in most of the 100 m events, whereas modifications on the start or turn distances (especially in the last turn) could provide elite swimmers with time improvements of practical importance on the 200 m events. The evaluation of races by individualised-distance parameters should be provided to elite swimmers in order to decide the most appropriate race segment configuration for each event.