Análisis descriptivo y comparativo de los goles conseguidos tras saques de esquina en la liga española 1ª división: temporadas 2015 y 2019 / Descriptive and comparative analysis of the goals achieved after corner kicks in the Spanish league 1st division: 2015 and 2019 seasons / Análise descritiva e comparativa dos gols marcados após escanteios na 1ª divisão do liga espanhola: temporadas de 2015 e 2019

El objetivo del estudio fue describir de manera exhaustiva la manera de obtener goles tras saque de esquina para analizar la existencia de diferencias, entre las temporadas 2014/15 y 2018/19 en la Liga de Primera División española. El estudio pretendió analizar la incidencia real de esta acción del juego e identificar qué variables están asociadas a la eficacia de la acción al analizar todos los saques de esquina que acaban en gol en dichas temporadas. Para ello se construyó una herramienta de registro en la que se incluyeron criterios contextuales y criterios relacionados con el desarrollo de la acción de gol. Como conclusión, los resultados evidencian una estimación de la tendencia hacia un predominio de los saques de esquina directos o de primera acción (2014/15) hacia saques de esquina de segundas acciones (2018/19). Se observó un incremento del número de jugadores que actúan y una pérdida del predominio del remate de cabeza como acción finalizadora. (AU)

The objectives of the study were to exhaustively describe the way of scoring goals after corner kicks in order to analyze the existence of differences, between the 2014/15 (n = 112) and 2018/19 (n = 90) seasons, in the Liga de Spanish First Division. The study aimed to analyze the real incidence of this game action and identify which variables are associated with the effectiveness of the action by analyzing all the SDE actions thatend in a goal in those seasons. As a main conclusion, the results could show a certain evolution of the predominance of direct or first-action corner kicks (2014/15) towards second or third-action corner kicks (2018/19). Increased the number of players involved in the action and a loss of the dominance of the header as a finishing action, probably related to the change in trend from direct corner kicks (2014/15) towardssecond-action corner kicks or rebounds (2018/19). (AU)

Os objetivos do estudo foram descrever exaustivamente a forma de marcar golos após pontapés de canto, de forma a analisar a existência de diferenças, entre as épocas 2014/15 (n=112) e 2018/19 (n=90), na primeira Liga Espanhola. O estudo teve como objetivo analisar a real incidência dessa ação no jogo e identificar quais variáveis que estão associadas à efetividade da ação analisando todas as ações da SDE que terminam em golos nessas temporadas. Como principal conclusão, os resultados puderam evidenciar uma certa evolução da predominância dos pontapés de canto diretos ou de primeira ação (2014/15) para os pontapés de canto de segunda ação (2018/19). Verificou-se ainda um aumento do número de jogadores envolvidos na ação e perdado domínio do cabeceamento como ação de finalização, provavelmente relacionado à mudança na tendência do canto direto (2014/15) para cantos ou ressaltos de segunda ação (2018/19). (AU)

Robust polarization state generation for long-range quantum key distribution.

We present a new compact and robust polarization state transmitter designed to execute the BB84 quantum key distribution protocol. Our transmitter prepares polarization states using a single commercial-off-the-shelf phase modulator. Our scheme does not require global biasing to compensate thermal and mechanical drifts, as both of the system's two time-demultiplexed polarization modes share a single optical path. Furthermore, the transmitter's optical path entails a double-pass through the phase modulation device for each polarization mode, allowing multiple phase rotations to be impinged on each light pulse. We present a proof-of-concept prototype of this transmitter topology and demonstrate a mean intrinsic quantum bit error rate below 0.2% over a 5 hour measurement.

Muscle strength and anaerobic performance in football players with cerebral palsy.

BACKGROUND: This is the first study that quantified the anaerobic performance in football players with cerebral palsy (CP). OBJECTIVE: This study aimed to examine anaerobic fitness in a population of football players with CP using vertical jumping (VJ) and Wingate tests. METHODS: Twelve players (age 26.8 ± 4.8 yr, body mass 66.2 ± 4.8 kg, height 173.7 ± 6.4 cm, body mass index 22.2 ± 1.9 kg m(-2)) from the Spanish National Football Team with CP which had 9.4 ± 3.7 years of playing experience performed the VJ and Wingate anaerobic tests. RESULTS: Vertical jump height was 20.0 ± 1.2 cm for squat jump (HSJ) and 23.9 ± 5.4 cm for countermovement jump (HCMJ). Wingate test peak power (PPOW) was 490.6 ± 125.8 W (7.35 ± 1.53 W kg(-1)). HCMJ was largely (r = -0.631, p = 0.028) and very-largely (r = -0.710, p = 0.01) associated with PPOW (W kg(-1)) and mean power output (MPOW) (W kg(-1)), respectively. Squat jump test peak power (W) showed a large association (r = -0.656, p = 0.021) with MPOW (W and W kg(-1)). The CMJ height resulted 19.5% higher than SJ. CONCLUSIONS: Results showed low VJ and anaerobic capacity of football players with CP compared to national players without CP and the general population. In football players with CP the difference (19.5%) between VJ with or without countermovement (CMJ-SJ) was higher than reported for national players without CP. Further studies examining the effect of football practice on neuromuscular performance in subjects with CP are warranted.

Effects of different agility training programs among first-grade elementary school students.

The aim of the study was to determine which agility training program (low, moderate or high contextual interference) was more effective in first-grade primary school students to provide reliable information to physical education teachers for designing more effective agility programs. A total of 57 first-grade elementary school students participated in the present study. They were randomized into three groups to compare the effects of three different agility training programs based on contextual interference: low contextual interference (N = 19), moderate contextual interference (N = 19), and high contextual interference (N = 19). Contextual interference refers to the relative amount of interference created when integrating two or more tasks into a particular aspect of a training session. Significant improvements in agility were found in the low (p < 0.01, ES = 1.79) and moderate (p < 0.05, ES = 0.61) contextual interference groups after a 4-week training period. These improvements were higher in the low contextual interference group. The high contextual interference group showed no improvements (p > 0.05, ES = 0.28) after the intervention program. Our results suggested that the low contextual interference program is still more effective than the moderate contextual interference program in this group of primary school students.

Correlation between agility and sprinting according to student age.

The purposes of the study were to assess sprinting and agility performance characteristics and to determine the relationship between these two motor skills in elementary education students. Sprinting and agility performance were assessed in 176 children (88 boys and 88 girls) divided into three groups: Group 1 (G1, N = 98; 48 boys and 50 girls), from the first year of elementary education; Group 2 (G2, N = 38; 15 boys and 23 girls), from the second year of elementary education; Group 3 (G3, N = 40; 25 boys and 15 girls), from the third year of elementary education. Significant differences (p < 0.001) were found in agility ability among the groups and between G1-G3 and G2-G3 in the 5 and 15 m sprint. Regarding gender of the students of the same age, significant differences (p < 0.001) between boys and girls in group G1 and G2 were obtained in the 5 and 15 m sprint. The correlation between agility and acceleration was significant but moderate (0.3 < r < 0.7) in all groups (G1, G2, and G3), in most cases. When the gender factor was included, the results were heterogeneous. Assessing this correlation according to age and gender produced heterogeneous results. For this reason, we think that both are independent qualities and that age and gender are two factors that influence the correlation results.

Influence of opposition on ball velocity in the handball jump throw.

The purpose of the present study was to investigate the influence of different degrees of opposition on ball velocity in the jump throw in elite, amateur and adolescent team handball players. Thus, one hundred and nineteen elite, amateur and under 18 team handball players performed jump throws under three different conditions: 1) without opposition, 2) with the opposition of the goalkeeper and 3) with the opposition of the goalkeeper and a defensive player. The degree of opposition was found to have a negative effect on ball velocity in all three groups (p < 0.001). Furthermore, the level of competition had a positive effect on ball velocity (p < 0.001). However, no interaction was found between the level of competition and the degree of opposition on ball velocity (p = 0.178). The findings of this study indicate that an increase of external stimuli probably influences throwing kinematics and thereby maximal ball velocity. However, experience does not seem to be a factor that can reduce the influence of these external stimuli. Key pointsThe degree of opposition had a negative effect upon ball throwing velocity in elite, amateur and adolescent handball players in the jump throw.It indicated that an increase of external stimuli influences the execution of throwing.Experience does not seem to be a factor that can reduce the influence of these external stimuli.

Biomecánica del vendaje funcional preventivo de tobillo (II) / Biomechanics of prophylactic ankle taping (II)

El uso del vendaje inelástico como método preventivo de los esguinces de tobillo está muy extendido entre los deportistas con riesgo de lesionarse durante la práctica deportiva, sobre todo en aquellos deportes en los que se realizan grandes saltos y cambios continuos de dirección a la máxima velocidad en los que las situaciones competitivas propician el contacto inevitable entre jugadores. Sin embargo siempre se han cuestionado sus efectos sobre el rendimiento deportivo y sobre la capacidad de amortiguar los impactos contra el suelo.En este estudio se pretende analizar los posibles efectos del vendaje preventivo inelástico sobre las fuerzas de reacción durante las fintas, así como las posibles consecuencias que la limitación de movimientos puede tener sobre el rendimiento deportivo en cuanto a la velocidad de ejecución de la finta y de un circuito de obstáculos. Además, se pretende analizar las posibles diferencias en función del grado de fatiga que alcanza el vendaje tras un entrenamiento de 30 minutos.Se registraron las fuerzas de reacción de una finta incluida en un circuito de obstáculos, realizada a la máxima velocidad, con una plataforma de fuerzas dinamométrica (125 Hz) en tres situaciones: con vendaje antes y después del entrenamiento y sin vendaje.Los resultados del estudio no reflejan cambios significativos en los picos de fuerza ni en los impulsos mecánicos en ninguna de las tres situaciones estudiadas. Tampoco se han encontrado cambios significativos en la localización temporal de los picos de fuerza, lo que indica que el vendaje no afecta a la capacidad de amortiguación de los impactos. El vendaje no ha modificado de forma significativa la distancia entre los instantes de máxima supinación y los picos de fuerza. Aunque el rendimiento de los sujetos no se ha modificado significativamente ni en el circuito ni en la finta, los mejores tiempos del circuito se han registrado con el vendaje nuevo mientras que los mejores tiempos de finta se han registrado con el vendaje fatigado, por lo que es posible que una excesiva restricción pueda peljudicar al rendimiento

The wear of taping like a preventive method of ankle sprains is widespread among sports subjects with a potential risk of injury during the sports practice, primarily in those sports were highjumps and continuous cutting movements are developed at the maximum speed and the contact among players can't be avoided. However, there are many doubts about the taping effects on performance and on landing forces absorption capability.The aim of the present study was to analyse taping effects on the absorption oflanding impacts during a feint on healthy subjects and to analyse the changes on sports speed performance developing a feint and developing a multiple cutting movement circuit.Reaction forces of a feint, included in a cutting movements circuit developed at the maximum speed, were registered with a dynamometric platform (125 Hz) with taping (before and after training) and without taping.The study results showed no significant changes on landing force peaks and on mechanic impulses. Significant changes were not found on the temporary location of the landing force peaks, so taping has no effects on the absorption of landing impacts capability. Taping did not significantly change the distance between maximum supination and the force peaks instants.Although the speed performance was no significantly affected, neither the feint speed nor the circuit speed, the best scores on the circuit were developed with the tape before the training and the best scores on the feint were developed without the taping, so is possible that an excessive restriction can affect the speed performance