Modeling Dynamical Positional Physical Data on Field Zones Occupied by Playing Positions in Elite-Level Futsal: A Comparison Between Running Velocities, Accelerations, and Decelerations.

ABSTRACT: Serrano, C, Felipe, JL, García-Unanue, J, Vicente Gimenez, J, Jiménez-Linares, L, Ibáñez, E, Hernando, E, Gallardo, L, and Sánchez-Sánchez, J. Modeling dynamical positional physical data on field zones occupied by playing positions in elite-level futsal: a comparison between running velocities, acceleration, and deceleration. J Strength Cond Res 37(1): 200-206, 2023-The aim of this study was to analyze the influence of playing positions on the physical demands and the specific court zones occupied during official futsal games. The total number of observations were 188, corresponding to 8 matches from the first division of the Spanish Futsal League during the 2019-2020 season. All dynamic motion representations were recorded using an 18 Hz device with ultra-wideband technology and local positioning system installed on the futsal pitch for each position. Python Data Analysis Library, Matplotlib, and Python programming language were applied as computational tools to generate visual analysis of figures to represent every physical demand analyzed. An analysis of variance test showed differences between playing positions, specifically, for winger position (p < 0.05). Based on eta-square coefficients, all variables showed large effects, except acceleration distance zone 1 (1-2 m·s-2). Accordingly, the visual representation of positional dynamic motion data showed differences in the physical demands and the court zone occupied by the different playing positions. This innovative visual analysis allows fitness coaches to associate the physical demands with court zones occupied by different playing positions, and it aids in the design of training drills associated with futsal competition requirements.

Characterisation of Goal Scoring Patterns during Open Play Related to Zone Pitch Division and Number of Players Involved in the 2018 FIFA World Cup.

The aim of this study was to characterise all the goal scoring patterns during open play (elaborate attacks versus counterattacks) related to zone pitch division and the number of players involved in the 2018 FIFA World Cup in Russia. An Iterative Dichotomiser 3 (ID3) decision tree algorithm was used to classify all the goal scoring patterns (94 goals in 64 matches). The results did not show statistical differences between the type of scoring goal during the 2018 FIFA World Cup (p > 0.05; ES = Moderate). According to the result of the patterns of how the goals were achieved, an ID3 algorithm decision tree with seven classification decision nodes was calculated. Consequently, this study may aid national team coaches for the next World Cup to establish notational analyses and spatial-temporal relations to understand how scoring patterns during open play are related to zone pitch division and the number of players involved.

A Hybrid Online Off-Policy Reinforcement Learning Agent Framework Supported by Transformers.

Reinforcement learning (RL) is a powerful technique that allows agents to learn optimal decision-making policies through interactions with an environment. However, traditional RL algorithms suffer from several limitations such as the need for large amounts of data and long-term credit assignment, i.e. the problem of determining which actions actually produce a certain reward. Recently, Transformers have shown their capacity to address these constraints in this area of learning in an offline setting. This paper proposes a framework that uses Transformers to enhance the training of online off-policy RL agents and address the challenges described above through self-attention. The proposal introduces a hybrid agent with a mixed policy that combines an online off-policy agent with an offline Transformer agent using the Decision Transformer architecture. By sequentially exchanging the experience replay buffer between the agents, the agent's learning training efficiency is improved in the first iterations and so is the training of Transformer-based RL agents in situations with limited data availability or unknown environments.

Arquitectura muscular en cuatro grupos de mujeres jóvenes / Muscle arquitecture in four groups of young women

La arquitectura muscular se define como la disposición geométrica de las fibras musculares, e influye significativamente en las características funcionales del músculo. Los objetivos de este estudio han sido analizar y comparar, en cuatro grupos de mujeres jóvenes, con distinto nivel de actividad física, la arquitectura de la musculatura extensora del miembro inferior, estudiando las diferencias entre músculos. Los grupos analizados fueron 12 jugadoras de voleibol de élite (ELITE), 12 jugadoras de voleibol de nivel medio (MED), la estudiantes de Educación Física (EST) y 12 mujeres sedentarias jóvenes (SED). Se obtuvieron valores del grosor muscular, los ángulos de pennación y la longitud de fascículos de los músculos vasto lateral (VL), gastrocnemio medial (OM) y gastrocnemio lateral (01), mediante ecografía, y se determinaron las características antropométricas de cada grupo. Las diferencias arquitectónicas entre músculos eran similares a las descritas en la bibliografía, y se correspondían con el tipo de acciones que desempefian. El VL presentaba un disefio orientado a la producción de fuerza a altas velocidades, debido a su grosor ya la longitud de sus fascículos. Se encontraron diferencias significativas en el grosor muscular y las longitudes de fascículos del grupo SED, comparado con los grupos MED y ELITE, lo que se relacionaría con la capacidad de las jugadores de voleibol para desarrollar niveles más altos de fuerza y velocidad debido a un mayor número de sarcómeros en paralelo y en serie. Las mayores longitudes de fascículos encontradas en el grupo ELITE estarían relacionadas con el tipo de entrenamiento que lleva a cabo, que incluye una gran cantidad de saltos y movimientos que producen alargamiento de los fascículos musculares mediante acción mecánica. Las correlaciones entre longitudes de fascículos y grosor muscular en los grupos ELITE y MED concuerdan con aquellas encontradas en deportes donde la fuerza explosiva y la velocidad son fundamentales para el rendimiento

Muscle architecture describes the geometric design of a muscle. It will have a great influence in tue force generating capacity and fue shortening velocity of skeletal muscle. The purposes of this study were to analyse and compare, in four groups of young women with different levels of physical activity, fue architectural characteristics of lower limb extensor muscles, and tue differences between muscles. Twelve elite female volleyball players (ELITE), 12 club level female volleyball players (MEDIO), 10 physical education students (EST) and 12 sedentary youngwomen (SED) volunteered for fue study. Muscle thickness, pennation angies and fascicle length of vastus lateralis (VL), gastrocnemius medialis (GM) and gastrocnemius lateralis (GL) were analysed by means of ultrasonography, and tue anthropometric characteristics of each group were determined. The differences among muscles were similar to those reported in the literature, and were related to fue functional use of each muscle. The VL muscle architecture was related to the development of great forces at high contraction velocities, because of its muscle thickness and fascicle length. There were signillcant differences in muscle thicknesses and fascicle lengths between SED and the groups of volleyball players (MED and ELITE). These differences would be related to the ability to develop higher levels of force and velocity, due to the greater number of in-parallel and in-series sarcomeres. The longer fascicle lengths found in fue ELITE group would have been caused by their specific training, mainly composed by jumps and explosive movements that led to forced stretching of muscle fascicles. The correlations between fascicle lengths and muscle thickness in ELITE and MED are similar to those found in sports where explosive strength and speed are essential for the performance

Fuerzas de reacción del suelo en pies cavos y planos / Ground reaction forces in high-arch and flat feet

El objetivo de este estudio se ha centrado en medir las fuerzas de reacción en diferentes movimientos (marcha, carrera, cambio de dirección y amortiguación de caída) en una muestra de sujetos sedentarios sanos con pies planos y cavos. Participaron en el estudio 15 mujeres jóvenes (edad: 19,4 +/- 1.3 afios; peso: 57,17 +/- 8,98 Kg); 8 con pies planos (P) y 7 con pies cavo s (C). Fueron sometidas a una batería de pruebas: marcha (velocidad = 1,6 mis), carrera (velocidad = 3 mis), amortiguación de caída (desde una altura de 0,75 m) y cambio de dirección. Se estudiaron las fuerzas verticales, anteroposteriores y mediolaterales, utilizando una plataforma de fuerzas piezoeléctrica. Aparecieron diferencias significativas (p<0,01) entre pies planos y cavos en la duración del apoyo en el cambio de dirección, siendo mayores en los planos (C = 0,30 +/- 0,04 s Y P = 0,37 +/- 0,04 s) y en el primer pico de fuerza de la amortiguación de la caída (p<0,05), con valores superiores en los cavos (C = 5,78 +/- 1,29 BWy P = 4,29 +/- 0,84 BW). El resto de variables estudiadas no mostraron diferencias significativas, aunque todos los picos de fuerza en los movimientos máximos fueron mayores en el grupo con pies cavos y los picos de impacto en marcha y carrera fueron ligeramente superiores en los pies planos. El grado de significación estadística no tiene por qué ser el límite que marque el mayor o menor riesgo de futura lesión asociada a las fuerzas de reacción. Pequefias y no significativas diferencias podrían marcar un incremento sustancial del riesgo. Cabe destacar los mayores valores registrados en los pies cavos, en los movimientos máximos, en los que existiría un mayor riesgo para ellos. Por otro lado las mínimas o nulas diferencias observadas en los patrones de movimiento podrían explicarse por adaptaciones que realiza el sujeto en el movimiento

The aim of this study was to measure the ground reaction force s in different movements (walking, running, changes of direction and landing), in a sample of sedentary subjects with high-arch feet or flat feet. Fifteen young women volunteered for the study (age: 19,40 +/- 1,29 years; weight: 57,17 +/- 8,98 Kg); 8 with flat feet (P) and 7 with high -arch feet (C). AlI of them carried out the following tests on a force platform: walking (speed = 1,6 mis), running (speed = 3 mis), drop landing (height = 0,75 m), and changes of direction. Vertical, horizontal and mediolateral ground reaction forces were collected using a piezoelectric force platform. There were significant differences (p < 0,01) between flat and high-arch feet in the contact time during the change of direction test, with greater contact times in subjects with flat feet (C = 0,30 +/- 0,04 s Y P = 0,37 +/- 0,04 s), and in the first peak vertical force during landing (p<0,05), with greater values in subjects with high-arch feet (C = 5,78 +/- 1,29 BW Y P = 4,29 +/- 0,84 BW). The other variables studied did not show significant differences between groups, although peak vertical force s for the maximum tests were greater in the high-arch feet group, and peak forces during walking and running were slightly greater for the flat feet group. The lack of significant differences does not have to be the limit to predict the risk of injury provoked by greater peak forces. Small and not significant differences might be enough to increase this risk. The higher force values found in the high-arch feet group during maximal tests show a higher risk of injury during these kinds of movements. The minimal differences found in the movement pattems between groups could be explained by individual adaptations during the tests

Medición directa de la potenciá con tests de salto en voleibol femenino / Direct measurement of power with jump tests in female volleyball

La potencia mecánica en los tests de salto se puede medir tanto de forma directa, mediante plataforma de fuerzas, comocalculada (forma indirecta) a partir de la altura del salto y de la masa corporal de los sujetos, mediante diferentes fórmulas (Lewis, Harman y Sayers). El objetivo de este trabajo ha sido evaluar la potencia de extensión de los miembros inferioresen tests de salto en un equipo de voleibol femenino de nivel medio (n = 13) de forma directa e indirecta. Por otro lado,discutir acerca de la idoneidad de unos métodos frente aotros. Para ello, los sujetos realizaron tres tipos de saltossobre una plataforma de fuerzas: abalakov (ABK), salto con contramovimiento (CMJ) y salto sin contramovimiento (SJ). Los picos de potencia obtenidos han sido, para ABK: plataforma 3536 +/- 6;31 W; Lewis 839 +/- 120 W y Harman 2834 +/-: 542 W; para CMJ: plataforma 2856 +/- 554 W; Lewis 760 +/- 110 W; Harman 2408 +/- 465 W y Sayers 2703 +/- 450 W y para SJ: plataforma 2878 +/- 538 W; Lewis 677 +/- 106 W; Harman 1996 +/- 428 W y Sayers 2310 +/- 459 W La plataforma de fuerzas es el método más preciso para medir la potencia mecánica en tests de salto. La fórmula de Lewis ha infraestimado el pico de potencia (p<0,01). La fórmula de Harman también lo ha infraestimado, aunque en menor medida (p<0,01). Con la fórmula de Sayers se han obtenido unos valores más aproximados a los de la plataforma de fuerzas, aunque también han sido significativamente diferentes (p<0,01). La conclusión que se desprende es que lo ideal sería evaluar la potencia de forma directa pero si no se dispusiera de instrumentos, con la fórmula de Sayers se podrían obtener unos valores muy cercanos

Mechanical power in jump tests can be directly measured by a force platform, or estimated (indirect way) from a subject's jump height and body mass, by means of different equations (Lewis, Harman and Sayers). The aim ofthis studywas to evaluate, directly and indirectly, peak power from lower extremities usingjump tests in a club level female volleyball team (n= 13). A secondarypurposewas to compare if one method is more suitable than the others. Subjects performed three different jump tests, on a force platform: Abalakov (ABK), countermovementjump (CMJ) and squatjump (SJ). Peak power in ABK was 3536 +/- 631 W (force platform); 839 +/- 120 W (Lewis) and 2834 +/- 542 W (Harman). Peak power in CMJwas 2856 +/- 554 W (force platform); 760 +/- 110 W (Lewis); 2408 +/- 465 W (Harman) and 2703 +/- 450 W (Sayers), and for the SJ, peak power was 2878 +/- 538 W (force platform); 677 +/- 106 W (Lewis); 1996 +/- 428 W (Harman) and 2310 +/- 459 W (Sayers). The force platform is the more accurate instrument to measure mechanical power in jump tests. The Lewis equation underestimated peak power (p<0,01). The Harman equation also underestimated peak power, but less than Lewis equation (p<0,01). The Sayers equation gave measures closer to those taken from the force platform, although they have been significantly different, as well (p<0,01). In conclusion, the betterwayto evaluate power would be directly, using a force platform. The Sayers equation seems to give power measures closer to those obtained by direct methods