This study aimed to examine the associations between lower-body explosive strength (squat jump—SJ, and countermovement jump—CMJ), speed (10- and 35-m linear sprints), and agility (t-test) capacities, after controlling for crucial predictors such as chronological age (CA) and body composition. The sample was composed of 164 adolescent male football players from under 19, under 17, and under 15 age groups. Body fat percentage (BF%) was significantly and positively related to body mass, speed, and agility. In contrast, BF% was a significant negative predictor of lower-body explosive strength. Sprint and t-test times were significantly and negatively correlated with lower-body explosive strength. After controlling for CA and body composition, SJ was the most significant predictor, accounting for 36 to 37% of the variance observed in the 35 m linear sprint and the t-test performance. Our main results suggest that lower-body explosive strength, particularly in the SJ, is a significant predictor of male adolescent male football players’ speed and agility capacities. Conversely, detrimental relationships between BF% and these outcomes were observed. Sports agents should consider lower-body explosive strength development as part of the youth football training process, particularly to improve maximal sprint and change of direction times, which are crucial to game performance.

Large-sided games (LSG) are commonly used in the training contexts for providing either technical/tactical or locomotor/physiological stimuli. Despite natural similarities with the official match, the locomotor profile seems to be different, which must be considered by the coaches to identify compensatory strategies for achieving the ideal dose of training. The aim of this study was two-fold: (1) to investigate the locomotor demands imposed by LSGs and the official matches; and (2) to compare the effect of different pitch sizes’ LSG conditions in the locomotor demands. This study followed an observational design. Sixteen professional football players from the same team (26.3 ± 3.0 years old) were included. The study was conducted over four weeks. The same GK + 10 × 10 + GK play format with different pitch sizes (i.e., area per player ranging between 195 m2 to 291 m2) was analyzed. Three official matches were also collected in which the 10 most demanding minutes were considered for further comparisons. Only the same players who participated in matches were considered in comparison with the LSG. The data were obtained using a 10-Hz global positioning system technology. Total distance (TD) and mechanical work (MW) scores increased 20% and 23%, respectively, between the smallest and biggest pitch sizes (p < 0.001). There was a significant difference in locomotor intensity metrics between opponents from different positions on the table (p = 0.001). The biggest LSG (i.e., 291 m2 per player) was the only one that required similar levels of locomotor intensity as required in the official full match. The present study demonstrates that LSG pitch size variation requires different locomotor intensities. Bigger pitch sizes cause an increase in TD and MW. In addition, considering the position on the table, the level of opponents induces different TD covered. Finally, the largest LSG simulates the official match more accurately.

The integration of methods to quantify the physical demands [e.g., Rating Perceived Exertion (RPE)] in small-sided games (SSGs) in younger soccer players, has been scarcely studied. In addition, few studies have been addressing the impact of balanced vs. unbalanced SSGs, in particular in youth players’ RPE. This study aimed to investigate differences between balanced and unbalanced format games in young soccer players’ RPE, controlling for different playing field sizes. The sample comprised 10 field players and 2 goalkeepers (Gk) being 13,55±0,51 years-old. The players performed 6 randomized different situations, following an identical methodology across the training days: (1) 4Vs.4+Gk (2) 4Vs.5+Gk, and (3) 4Vs.6+Gk. All situations were performed in 30x25m and 40x30m. The game situations lasted 5 minutes of practice and another 5 minutes of rest. After the execution of all game situations, participants were asked individually about their self-perceived effort, using the OMNI effort scale. In unbalanced format games when the difference in the number of players increases, RPE is lower. This tendency seems to be more evident in smaller compared to bigger playing field areas. The difference in RPE scores considering different dimensions of playing space seems not to be linear. Balanced soccer SSGs promote higher RPE than unbalanced soccer SSG. More studies on the topic are required considering different playing field areas as well as different players' backgrounds.  Resumen. La integración de métodos para cuantificar las demandas físicas [por ejemplo, Calificación del Esfuerzo Percibido (CEP)] en juegos reducidos (JR) en jugadores de fútbol más jóvenes, ha sido poco estudiada. Además, pocos estudios han abordado el impacto de los JR equilibrados frente a los no equilibrados, en particular en el CEP de los jugadores juveniles. Este estudio tuvo como objetivo investigar las diferencias entre los juegos de formato equilibrado y desequilibrado en el CEP de los jugadores de fútbol jóvenes, controlando los diferentes tamaños del campo de juego. La muestra estuvo compuesta por 10 jugadores de campo y 2 porteros (P) con 13,55 ± 0,51 años. Los jugadores realizaron 6 situaciones diferentes aleatorias, siguiendo una metodología idéntica a lo largo de los días de entrenamiento: (1) 4Vs.4 + P (2) 4Vs.5 + P, y (3) 4Vs.6 + P. Todas las situaciones se realizaron en 30x25m y 40x30m. Las situaciones de juego duraron 5 minutos de práctica y otros 5 minutos de descanso. Después de la ejecución de todas las situaciones del juego, se preguntó a los participantes individualmente sobre su esfuerzo autopercibido, utilizando la escala de esfuerzo OMNI. En los juegos de formato desequilibrado, cuando aumenta la diferencia en el número de jugadores, el CEP es menor. Esta tendencia parece ser más evidente en las áreas de juego más pequeñas que en las más grandes. La diferencia en las puntuaciones de CEP considerando las diferentes dimensiones del espacio de juego parece no ser lineal. Los JR de fútbol equilibrado promueven un CEP más alto que el JR de fútbol desequilibrado. Se requieren más estudios sobre el tema considerando las diferentes áreas del campo de juego, así como los antecedentes de los diferentes jugadores.