Differences in strength and speed demands between 4v4 and 8v8 small-sided football games.

The aims of this study were (i) to characterise the acceleration demands of two different formats of small-sided game (SSG), i.e., 4v4 + goalkeepers (4v4 + GK) and 8v8 + goalkeepers (8v8 + GK); (ii) to analyse the correlation between performance in power-based tests and acceleration-based physical loading during the two different SSG formats and (iii) to analyse the neuromuscular-induced fatigue. Eighteen adult male footballers participated in the study (20.7 ± 1.0 years, 178 ± 5 cm and 71.4 ± 2.1 kg). Baseline measurements were obtained from countermovement jumps, 15 s repeated jumps and 5 and 15 m sprints. A total of 36 min was analysed for each SSG (4v4 + GK: two sets of 3 × 6 min, and 8v8 + GK: 2 × 18 min). Heart rate, blood lactate, perceived exertion and movement pattern (GPS) were analysed. Distances covered by very-high-intensity activities and very-high-speed running were lower in 4v4 + GK than in 8v8 + GK (effect sizes (ES) = -0.69 ± 0.67 and -1.04 ± 0.67, respectively; very likely), while accelerations and decelerations were higher in 4v4 + GK than in 8v8 + GK (ES = 1.13-1.52; almost certainly). Blood lactate concentrations were higher (ES = 1.40 ± 0.58; almost certainly) and players perceived themselves to be more tired (ES = 0.80-2.31; almost certainly) after 4v4 + GK than after 8v8 + GK. Sprint ability in 5 and 15 m tests decreased (ES = 0.87 ± 0.58 and 0.89 ± 0.58, respectively; almost certainly) only after 4v4 + GK. This SSG format appeared more demanding in relation to repetitions and fatigue development of muscle power-based actions than 8v8 + GK. It may therefore be logical to use the former type of SSG to target development of power-related football actions.

The relative age effects in young soccer players and it relations with the competitive level, specific position, morphological characteristics, physical fitness and technical skills / O efeito da idade relativa em jovens futebolistas e suas relações com o nível de competição, posição específica, características morfológicas, capacidade física e habilidades técnicas / El efecto de la edad relativa de los futbolistas jóveves y si relación con el nivel de competencia, puesto específico, la morfología, la capacidad física y habilidades técnicas

This study investigated the relative age effects (RAE) in young soccer players and it relations to morphological, technical and physical variables, in a sample of 267 male players from U17 and U19 categories. Our results showed significant differences by age quartiles in relation to the competition level (U17), field positions (U17 and U19) and the 30m sprint test (U19). In summary, no significant associations were identified on morphological characteristics, physical fitness and technical skills in relation to the RAE.

Este estudo investigou o efeito da idade relativa (EIR) em jovens futebolistas e suas relações com variáveis morfológicas, técnicas e físicas em uma amostra de 267 jogadores de categorias Sub17 e Sub19. Nossos resultados mostraram diferenças significativas em função dos quartis etários em relação ao nível de competição (Sub17), posição de campo (Sub17 e Sub19) e teste de velocidade de 30m (Sub19). Em geral, nenhuma associação significativa foi identificada nas características morfológicas, capacidades físicas e habilidades técnicas em relação ao EIR.

Este estudio investigó el efecto de la edad relativa (EIR) en futbolistas jóvenes y su relación con variables morfológicas, técnicas y físicas en una muestra de 267 jugadores de las categorías Sub17 y Sub19. Nuestros resultados mostraron diferencias significativas según cuartiles de edad en comparación con el nivel de competencia (Sub17), la posición de campo (Sub17 y Sub19) y la prueba de velocidad de 30 metros (U19). En general, no hay asociación significativa fue identificado en las habilidades morfológicas, físicas y habilidades técnicas en relación con el EIR.