The aim of this study was to analyze the influence of different large-sided games on the physical and physiological variables in under-13 soccer players. The effects on heart rate (HR) and physical demands of different number of players (NP) (7, 9, and 11) together with the relative pitch area (RPA) (100, 200, and 300 m) during two 12-minute repetitions were analyzed in this study. The variables analyzed were mean, maximum and different intensity zones of HR; total distance (TD); work:rest ratio (W:R); player load (PL); 5 absolute and 3 relative speed categories. The results support the hypothesis that a change in pitch dimensions affects locomotor activity more than the NP does but also refute the hypothesis that the change in the NP has a greater effect on HR. To be more specific, an increase in the RPA per player (300/200/100 m2) was associated with higher values of the following variables: TD (2,250-2,314/2,003-2,148/1,766-1,845 m), W:R (0.5-0.6/0.4-0.5/0.3 arbitrary unit [AU]), PL (271-306/246-285/229-267 AU), %HRmean (85-88/85-89/81-83%), %HRmax (95-100/97-100/95-98%), and affected the percentage of time spent in both absolute (above 8 km·h(-1)) and relative speed (above 40% Vmax) categories (p ≤ 0.05, effect size: 0.31-0.85). These results may help youth soccer coaches to plan the progressive introduction of large-sided games so that task demands are adapted to the physiological and physical development of participants.

The aim of the study was to assess the relationship of external and internal training load (TL) indicators with the objective and subjective fatigue experienced by 15 semi-professional football players, over eight complete weeks of the competition period in the 2015–2016 season, which covered microcycles from 34th to 41st. The maximum heart rate (HRmax) and maximum speed (Vmax) of all the players were previously measured in specific tests. The TL was monitored via questionnaires on rating of perceived exertion (RPE), pulsometers and GPS devices, registering the variables: total distance (TD), player load 2D (PL2D), TD at >80% of the Vmax (TD80), TD in deceleration at < -2 m⋅sec-2 (TDD <-2), TD in acceleration >2 m⋅sec-2 (TDA >2), Edwards (ED), time spent at between 50 and 80% (50–80% HRmax), 80–90% (80–90% HRmax), and >90% of the HRmax (>90% HRmax), and RPE both respiratory/thoracic (RPEres) and leg/muscular (RPEmus). All the variables were analyzed taking into account both the absolute values accumulated over the week and the normalized values in relation to individual mean competition values. Neuromuscular fatigue was measured objectively using the countermovement jump test and subjectively via the Total Quality Recovery (TQR) scale questionnaire. Analytical correlation techniques were later applied within the general linear model. There is a correlation between the fatigue experienced by the player, assessed objectively and subjectively, and the load accumulated over the week, this being assessed in absolute and relative terms. Specifically, the load relative to competition correlated with the physical variables TD (-0.279), PL2D (-0.272), TDD < -2 (-0.294), TDA >2 (-0.309), and sRPEmus (-0.287). The variables related to heart rate produced a higher correlation with TQR. There is a correlation between objectively and subjectively assessed fatigue and the accumulated TL of a player over the week, with a higher sensitivity being shown when compared to the values related to the demands of competition. Monitoring load and assessing fatigue, we are closer to knowing what the prescription of an adequate dose of training should be in order for a player to be as fresh as possible and in top condition for a match. Normalizing training demands with respect to competition could be an appropriate strategy for individualizing player TL.

The aim of the present study is to analyse the influence of different large-sided games (LSGs) on the physical and physiological variables in under-12s (U12) and -13s (U13) soccer players. The effects of the combination of different number of players per team, 7, 9, and 11 (P7, P9, and P11, respectively) with three relative pitch areas, 100, 200, and 300 m2 (A100, A200, and A300, respectively), were analysed in this study. The variables analysed were: 1) global indicator such as total distance (TD); work:rest ratio (W:R); player-load (PL) and maximal speed (Vmax); 2) heart rate (HR) mean and time spent in different intensity zones of HR (<75%, 75–84%, 84–90% and >90%), and; 3) five absolute (<8, 8–13, 13–16 and >16 Km h-1) and three relative speed categories (<40%, 40–60% and >60% Vmax). The results support the theory that a change in format (player number and pitch dimensions) affects no similarly in the two players categories. Although it can seem that U13 players are more demanded in this kind of LSG, when the work load is assessed from a relative point of view, great pitch dimensions and/or high number of player per team are involved in the training task to the U12 players. The results of this study could alert to the coaches to avoid some types of LSGs for the U12 players such as: P11 played in A100, A200 or A300, P9 played in A200 or A300 and P7 played in A300 due to that U13>U12 in several physical and physiological variables (W:R, time spent in 84–90%HRmax, distance in 8–13 and 13–16 Km h-1 and time spent in 40–60%Vmax). These results may help youth soccer coaches to plan the progressive introduction of LSGs so that task demands are adapted to the physiological and physical development of participants.

The purpose of this study was to investigate the structure of interrelationships among external (eT) and internal (iT) training intensity metrics and how these vary depending on game format in soccer. The variables were collected from 16 semi-professional players in seven types of small, medium, large-sided, and simulated games (SG). The eT variables were (per min): peak velocity (Vmax), total distance (DTmin), distance covered at velocities less than 60% (D < 60%min), between 60 and 80% (D > 60%min), and more than 80% (D > 80%min) of the maximal velocity, player load (PLmin), and distance covered accelerating at more than 2 m•s-2 (Daccmin) and decelerating at less than −2 m•s-2 (Ddecmin). The iT variables were: Edwards arbitrary units (EDWmin) and time spent at more than 80% of the maximal heart rate (T > 80% HRmin). All game formats were represented by three principal components (PC), explaining from 66.9 to 76.0% of the variance. The structure of the interrelationships among variables involved similar distributions in the PCs that are related to energetic production systems, such as the strength/neuromuscular dimension (PLmin and/or Daccmin and Ddecmin, complemented by DTmin and D < 60%min), the endurance/cardiovascular dimension (EDWmin), and the velocity/locomotion dimension (Vmax, D > 60%min, or D > 80%min). A particular combination of external and internal intensity measures is required to describe the training load of game formats.

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Purpose: The objectives of the present study were (1) to analyze the internal and external load profile of training and competition carried out by semiprofessional football players during a 27-week period and (2) to examine the possible link between this type of periodization and players’ fitness status and their readiness to compete. Methods: Training and match data were obtained from 26 semiprofessional football players belonging to the reserve squad of a Spanish La Liga club during the 2018/19 season. For the purpose of this study, the distribution of external and internal load during a typical training microcycle, with 6 or 7 days between matches, was analyzed. Five types of sessions were considered: strength, duration, velocity, preofficial match, and official match. Results: The results showed a different internal and external load profile for each type of session, with the load being consistently higher during matches when compared with training sessions (28.9%–94% higher), showing significant differences in all the variables. There was a clear tapering strategy in the last days of the week to arrive with enough freshness to compete, shown by the decrease of the values in the 2 days before the match (15%–83% reduction, depending on the variable). Furthermore, the horizontal alternation of the load allowed the players to maintain their fitness level during the 27-week period. Conclusions: Our findings suggest that this weekly periodization approach could help achieve a double conditional target, allowing a short tapering strategy to face the match with enough freshness and serving as a strategy for maintaining or optimizing players’ physical performance during the season.

Título: Influencia de la longitud del campo en los comportamientos inter e intra -equipo en jóvenes jugadores de fútbol. Resumen: El comportamiento táctico puede verse afectado por los cambios en los formatos de juegos reducidos (SSG). El objetivo del presente estudio fue analizar la influencia de diferentes longitudes del terreno de juego en formatos SSG-de-7 jugadores en jóvenes futbolistas. 14 jugadores masculinos de fútbol en cada grupo de edad (13 y 14 años, U13 y U14, respectivamente) se dividieron en dos equipos de siete jugadores, quienes jugaron en cuatro SSGs de 7 minutos de duración, intercalados con 4 minutos de recuperación pasiva. La única modificación en el formato SSG fue longitud del terreno: 60 m (SSG60), 50 m (SSG50), 40 m (SSG40) y 30 m (SSG30), mientras que la anchura del campo de 40 m se mantuvo constante. Las variables utilizadas para caracterizar el comportamiento colectivo se agruparon en: a) variables intra-equipo, es decir, la longitud del equipo (L), ancho del equipo (W), el área efectiva de juego del equipo o convex hull (CH), y el strech index (SI); y b) las variables inter-equipo, es decir, la distancia entre los centroides (DC), la longitud de los dos equipos (L2), la anchura de los dos equipos (W2), envolvente convexa de los dos equipos (CH2), y el índice de estiramiento de los dos equipos (SI2). Los resultados revelan diferentes comportamientos intra e inter-equipo de acuerdo al formato de SSG y la edad del jugador. Las variables L, CH, SI, DC, L2, CH2, y SI2 aumentaron con el incremento en longitud del terreno, mientras que W y W2 mostraron sólo cambios mínimos. Las diferencias fueron mayores en el grupo U13, lo que sugiere que los jugadores más jóvenes fueron más propensos a variar su comportamiento colectivo en respuesta a los cambios de alargar el terreno de juego, inter-tarea, especilamente en los campos más largos (SSG50 y SSG60). Por el contrario, utilizando el análisis de la entropía, mayor imprevisibilidad de comportamiento del equipo se observó en el grupo U14, intra-tarea, en comparación con el grupo U13. En general, los resultados sugieren que las respuestas a la limitación de las tareas, tales como la modificación de la longitud del espacio y el espacio relativo de juego, son dependientes de la edad (experiencia, habilidad) y esto es algo que los entrenadores deben tener en cuenta al diseñar los SSGs para desarrollar comportameintos tácticos colectivos. Palabras clave: Constreñimiento de tareas; comportamiento táctico; dispositivos GPS; deportes de equipo; entrenamiento.Abstract: Tactical behavior could be affected by changes in small-sided game (SSG) formats. The aim of the present study was to analyze the influence of different pitch lengths during 7-a-side SSGs played by young football players. Fourteen male soccer players in each age group (13 and 14 years old, U13 and U14 teams) were divided in two teams of seven players who played four SSGs of 7 minutes, interspersed with 4 minutes of passive recovery. The only modification to the SSG format was pitch length: ...