Aim to investigate internal and external load in three different game formats (8 v 8, 5 v 5, 3 v 3 with 80 m2 per player) of small-sided games (SSG) in Chinese elite youth football players. Twenty-nine elite male football players (age: 18.3 ± 0.5 years (mean ± SD), height: 175 ± 6 cm, weight: 65.5 ± 6.3 kg) participated in randomized order in the three formats. Each session consisted of 20 min: 3 v 3 on a 24 × 20-m pitch, 5 v 5 on a 32 × 25-m pitch, or 8 v 8 on a 40 × 32-m pitch all equalling 80 m2 per player. Each player was recorded once in each format. Using GPS-units and heart rate belts and blood lactate measured the two kinds of load. 8-10% higher total distance (P < 0.01) was observed in 8 v 8 and 5 v 5 compared with 3 v 3 (1627 ± 240 and 1595 ± 243 m vs. 1477 ± 179 m, ES = 0.55-0.71). Higher distance (P < 0.001) was covered with high speed running (HSR: > 14 km/h) in 8 v 8 and 5 v 5 than 3 v 3 (154 ± 94 m and 133 ± 59 m vs. 77 ± 35, ES = 1.09-1.15), whereas very high speed running distance (> 21 km/h) was higher (P < 0.01) in 8 v 8 than 5 v 5 and 3 v 3 (15.2 ± 19.5 vs. 5.3 ± 6.7 and 1.0 ± 0.4 m, ES = 0.69-1.03) and in 5 v 5 than 3 v 3. No difference was found between game formats in the number of intense accelerations nor intense decelerations. Blood lactate (3.5 ± 2.3 vs. 2.8 ± 1.9 vs. 2.4 ± 1.5 mmol · L-1, P = 0.201) and mean heart rate (155 ± 21 vs. 160 ± 11 vs. 157 ± 17 bpm, P = 0.254) was not different between 8v8, 5v5 and 3v3 game formats. Distance covered in total and in highest speed zones was higher in SSG formats with more players, which, however, did not lead to differences in internal load measured by heart rate and blood lactate.

The purpose of this study was to compare the external load in competitive (official) and non-competitive matches (friendly, training and modified-sided games) in professional soccer players. Time-motion data for 10 elite male soccer players (age = 20.1 ± 2.1 years; body height = 178.8 ± 5.9; body mass = 71.4 ± 7.3; % body fat = 11.0 ± 1.1 and VO2max = 55.96 ± 3.3) from a professional Spanish first division team were recorded during official (n = 12), friendly (n = 7) and training (n = 6) matches and a 5 vs. 5 + goalkeepers modified-sided game (n = 3). GPS devices were used to monitor players\' external loads: total distance covered, distance covered at different speeds (<13.9 km·h-1, >14, >18, >21 and >25 km·h-1), peak speed (km·h-1), and the number of accelerations and decelerations (1.5-2.5 m·s-2, 2.5-4 m·s-2 and 4-8 m·s-2). One-way analysis of variance of the magnitude-based inference was used to determine differences between matches. Data indicated that official matches scored statistically higher peak speeds (ES = 1.40-2.20). In modified-sided games more total distance was covered at <13.9 km·h-1 and >14 km·h-1 than in regular matches (ES = 0.72-2.21), but lower distances were covered at >21 km·h-1 and >25 km·h-1 than in official and friendly matches (ES = 0.51-2.53) and at >25 km·h-1 than in training matches (ES = 0.92). Likewise, the modified-side games showed a greater number of accelerations and decelerations than other types of matches (ES = 1.46-2.51). This work shows that friendly and training matches, in conjunction with modified-side games, are suitable tools to prepare soccer players for official matches.

School-based programmes have shown promising results in the reduction of aggressive behaviour, but the effectiveness of physical activity modalities among adolescents remains to be determined. The aim of this study was to determine the effects of a school-based soccer programme on physical fitness and aggression in adolescent students. One hundred and five high school students were randomized to a small-sided soccer training group (SG) or a control group (CG). In addition to the regular physical education classes performed as part of a curriculum, the SG completed eight months of small-sided soccer training twice a week after school. Aerobic fitness (YYIR1), vertical jump (VJ), backward overhead medicine ball throw (BOMBT), and Buss and Perry\'s aggression questionnaire were evaluated before and after eight months of training. Greater improvements were observed in the SG than in the CG in the BOMBT (%diff=4.3, ŋp 2=.308) and YYIR1 tests (%diff=2.2, ŋp 2=.159), and physical aggression subscale (%diff=-12.1, ŋp 2=.144). Extra, school-based recreational soccer for adolescents was accompanied by a significant improvement in physical fitness, compared to physical education classes only. Moreover, the implementation of recreational soccer into regular physical education classes seems to be a potentially appropriate stimulus for reducing aggression in high-school students.

This study examined the effects of induced mental and muscular fatigue on soccer players\' physical activity profile and collective behavior during small-sided games (SSG). Ten youth soccer players performed a 5vs5 SSG under three conditions: a) control, playing without any previous activity; b) muscular fatigue, playing after performing a repeated change-of-direction task; c) mental fatigue, playing after completing a 30 min Stroop color-word task. Players\' positional data was used to compute time-motion and tactical-related variables. The muscular fatigue condition resulted in lower distances covered in high speeds (∼27%, 0.3; ±0.5) than the control condition. From the tactical perspective, the muscular fatigue condition resulted in lower distance between dyads and players spent ∼7% more time synchronized in longitudinal displacements than the control condition (0.3; ±0.3). Additionally, players spent ∼14% more time synchronized with muscular fatigue than with mental fatigue (0.7; ±0.3). The mental fatigue condition resulted in a very likely more predictable pattern in the distance between dyads than in muscular fatigue condition (0.4; ±0.2). Also, the mental fatigue possibly decreased the teams\' stretch index when compared with control (0.2; ±0.3) and likely increased compared with muscular fatigue (0.5; ±0.5). The better levels of longitudinal synchronization after muscular fatigue, might suggest the usage of tactical-related tasks after intense exercise bouts. The lower physical performance and time spent longitudinally synchronized after mental fatigue, should alert to consider this variable before matches or training activities that aim to improve collective behavior.