Tensiomyography (TMG) is a relatively new technique to assess the muscles mechanical properties in response to a single electrical stimulus. The purpose of the present study was to assess the acute effect of a foam roller (FR) in the rectus femoris muscle using TMG. Seventeen male professional soccer players (age 21.4 ± 3.8 years, height 180.5 ± 7.7 cm, and mass 73.6 ± 10.7 kg) performed 4 sets of with a duration of 15 s using the foam roller (FR) on the dominant leg with 2 min of rest at 30 beats per minute. TMG measurements were performed at rest after the second and fourth sets for both the dominant and non-dominant leg (control). The TMG parameters analysed included stiffness (Dm), and contraction time (Tc). Substantial differences were not found between the legs at rest. For the non-dominant leg, substantial differences in Dm were found after the second and the fourth sets. For the dominant leg, substantial differences in Dm were not observed after the FR was applied. No differences in Tc were found for any of the measurements. Our results suggest that the use of a foam roller in slowly executed small sets maintains the muscle stiffness and the contraction time of the RF.

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Martínez-Cabrera, FI, Núñez-Sánchez, FJ, Losada, J, Otero-Esquina, C, Sánchez, H, and De Hoyo, M. Use of individual relative thresholds to assess acceleration in young soccer players according to initial speed. J Strength Cond Res 35(4): 1110–1118, 2021—The aims of the current study were (a) to analyze the characteristics of acceleration efforts using individual relative thresholds according to the initial speed during official matches in elite young soccer players according to player position and (b) to compare the differences between absolute and relative thresholds in assessing high-intensity acceleration. Player acceleration profiles were assessed using an individual relative threshold based on their acceleration capacity at different initial speeds (standing, 6, 10.8, and 15 km·h−1), and the number of accelerations (>75% of the maximal acceleration) performed during soccer matches was divided into 3 categories attending to the initial speed. (S1 = 0–7 km·h−1; S2 = 7.1–14 km·h−1; and S3 = ≥14.1 km·h−1). Within-group analyses showed that the number of accelerations performed in each category was higher when the effort started from a static or walking position than at moderate- or high-intensity running (S1 > S2 > S3; very likely to almost certain). Between-group analyses revealed substantial differences between some playing positions according to initial speed. In S1 and S3, central defenders had the lowest number of accelerations (likely to almost certain), whereas midfielders had the greatest number of high-intensity accelerations in S1 and S2. There were also substantial differences between the other playing positions (possibly to almost certain). Regarding relative and absolute thresholds (>3 m·s−2), the results showed that absolute threshold overestimated the number of high-intensity accelerations compared with the individual relative threshold in S1 and underestimated the results in S2 and S3 (almost certain). The use of an individual relative threshold to measure acceleration demands allows to distinguish between the numbers of accelerations in function of the initial speed and playing positions. In addition, the absolute acceleration threshold could overestimate or underestimate the acceleration demands in young soccer players as a function of the initial speed. Then, the absolute acceleration thresholds should be taken with caution in the assessment of acceleration activities.

Abstract. The aim of the present study was to analyze the number and the % of maximum accelerations, and the distance covered among different soccer players’ positions, classifying them with GPS technology according to an individual threshold based on the maximum acceleration capacity. 20 players were observed during four matches (n=80). All players undertook a maximal running speed test to determine the maximal acceleration. Players’ activities during the matches were classified into four individual acceleration thresholds: acceleration starting from 0 to 13 km·h-1 and never reaching 18 km·h-1 (A1); acceleration starting from 0 to 13 km·h-1 and reaching 18 km·h-1 (A2); acceleration starting from 13 to 18 km·h-1 (A3); and acceleration starting above 18 km·h-1 (A4). During A1, Full-Backs performed a higher number of accelerations compared to other playing positions and reached a ~95% of the maximum acceleration. During A2, Full-Backs and Wide Midfielder performed a higher number of accelerations than Central Defenders and Forwards, and Central Midfielders reached an estimated intensity of 95% of the maximum acceleration. During A3, CM performed the highest number of accelerations compared to the rest of the groups, while F reached an estimated intensity of 78% of their maximum acceleration. This individualized threshold could help coaches assess players’ physical performance and improve it, or to avoid injuries.Resumen. El objetivo del presente estudio fue analizar el número, % de la aceleración máxima y la distancia recorrida por las diferentes posiciones de juego, clasificándolos según un umbral individual para cada jugador basado en la máxima capacidad de aceleraración usando la tecnología GPS. Un total de 20 jugadores fueron evaluados durante 4 partidos (n=80). Todos los participantes realizaron un sprint a la máxima velocidad de carrera para determinar su capacidad máxima de aceleración. La actividad de los jugadores durante los partidos fue dividida en 4 categorías individuales de aceleración: A1, aceleración de 0 a 13 km·h-1 y sin llegar a 18 km·h-1; A2, aceleración desde 0 hasta 13 km·h-1 y alcanzando 18 km·h-1; A3, aceleración que inicia desde los 13 km·h-1 hasta los 18 km·h-1; A4, aceleración que comienza a una velocidad >18 km·h-1. En A1, los defensas laterales realizaron un mayor número de aceleraciones en comparación con las otras demarcaciones de juego y logrando una intensidad ~ 95% de su aceleración máxima. En A2, los defensas laterales y centrocampistas laterales realizaron un mayor número de aceleraciones que los defensas centrales y delanteros, consiguiendo los centrocampistas una intensidad aproximada del 95% de su máxima aceleración. En A3, los centrocampistas realizaron una cantidad superior de aceleraciones que el resto de grupos, mientras que los delanteros lograron una intensidad aproximada del 78% de su máxima aceleración. Estos umbrales individualizados podrían ser de gran utilidad para permitir evaluar a los técnicos de forma más precisa el rendimiento físico de los jugadores, permitiéndoles con ello mejorar su rendimiento y prevenir lesiones en futbolistas.

En los últimos años hemos visto una tendencia hacia un cambio en los conceptos y metodologías de entrenamiento de fútbol. El paradigma tradicional ha dado paso a nuevas propuestas que entienden el juego desde un plano holístico. Esta ruptura ha supuesto la aparición de nuevas formas de concebir el entrenamiento, emergiendo métodos de entrenamiento que se acercan a la especificidad del deporte. A día de hoy, contamos con diversos métodos de trabajo, entre los cuales podríamos citar el microciclo estructurado y la periodización táctica como lo que mayor interés y repercusión han suscitado debido a su utilización por entrenadores de éxito. En este sentido, la periodización táctica se fundamenta en la concepción del modelo de juego como elemento fundamental de donde parten los diferentes patrones de juego que deben ser reproducidos posteriormente en el entrenamiento. Debido a la falta de propuesta prácticas que manifiesten pautas claras para el desarrollo de un modelo de juego, en este trabajo trataremos de llevar a cabo un diseño propio a partir de i) un análisis conceptual sobre el modelo de juego, ii) identificación de los elementos que este debe de contener y iii) desarrollo práctico de cada uno de los elementos que sirva como hoja de ruta para aquellos profesionales que quieran profundizar en esta forma de concebir el entrenamiento en fútbol.Abstract. In recent years, we have identified a trend towards a change in the concepts and methodologies of soccer training. The traditional paradigm has given way to new proposals that understand the game from a holistic perspective. This break has led to the emergence of new ways of conceiving training. These training methods are close to each sport’s specificity. One of the methods that has raised more interest, due to its repercussions in professional soccer thanks to successful coaches, is the Tactical Periodization. This idea is based on the conception of game model as a fundamental element from which different game patterns grow, each of them needing to be reproduced later in the training. On account of a lack of practical proposals showing clear guidelines for the development of a game model, we try to present a personal design starting from i) a conceptual analysis of the game model, ii) the identification of the elements that this model needs to show, and iii) a practical development of each element, which serves as route map for those professionals who wish to delve into this training approach in soccer.