The present study aimed to determine the effects of the number of players on the playing style of junior high school students in small-sided games (SSG). The participants were 40 young male soccer players (age: 12.73 ± 0.63 years). The number of SSG players was set at 3 vs. 3 + 2 goalkeepers (GKs), 4 vs. 4 + 2 GKs, and 5 vs. 5 + 2 GKs, and the attacking play was measured using notational analysis. Statistical analysis was performed by unpaired t-test and χ² test. 3 vs. 3 had more passes to the GK than 4 vs. 4. Additionally, the occurrence rate of “dribbling” in the process leading to shooting was higher than 5 vs. 5. 4 vs. 4 had a higher occurrence rate of “forward direction” passing than 3 vs. 3. 5 vs. 5 had a higher number of passes and consecutive passes than 3 vs. 3 and 4 vs. 4. Also, the occurrence rate of “one-touch” in the process of shooting was higher than in 3 vs. 3. These results propose that 3 vs. 3 is characterized by individual goal scoring and GK’s participation in the attack, 4 vs. 4 is characterized by forward passing, and 5 vs. 5 is characterized by goal scoring with passing as a team.

The aim of this study was to investigate the effect of field length on physiological and external load in the same field area during small-sided games (SSGs) of soccer. Three field dimensions were used for SSGs: (1) wide field (wide; 20 × 30 m), (2) normal field (normal; 30 × 20 m), and (3) long field (long; 40 × 15 m). Eight college soccer players (average age: 21 ± 1 yr; height: 171.5 ± 2.9 cm; body mass: 66.9 ± 2.0 kg) were monitored using a heart rate monitor and a 18.18 Hz GPS device. Total distance, distance covered in four speed categories, maximum heart rate, and spend time in four heart rate zone categories were included in the analysis. Moreover, %Sprint. Vmax — defined as the peak sprinting speed during SSGs relative to the individual maximum sprinting speed measured in the prior 60 m sprint test—was included in the assessment. Statistically significant differences in total distance and %Sprint. Vmax were observed under the long condition; however, no significant differences were observed in the remaining measures. Study findings supported that for the same field area per player, extending field length increased total distance and sprinting speed during SSGs.

This study aimed to determine the effects of scoring patterns and time goal differences on wins and losses in recent years in rugby union.

We used data from 223 test matches and 318 matches from the Kanto University Rugby League Division 1, Kanto University Rugby Intercollegiate A Group, and Kansai University Rugby League A to compare the ratio of scoring methods and examine the influence of goal difference on wins and losses in time periods using logistic regression analysis.

The results revealed that tries and conversion goals were the most important scoring methods in university rugby and penalty goals in test matches. Considering close matches in university rugby, we found that the early and late stages of the match and early stages of the second half were the most critical periods. Regarding close matches in test matches, we found that making the most of scoring opportunities throughout the match was important. We found clear evidence that in both university rugby and test matches a one-sided game was expected to develop when the final goal difference was 8 points or more, whereas goal difference at any time did not affect the game’s outcome.

It should be acknowledged that several factors (including physical and psychological ones) are involved in sports injuries and conditioning. However, most reports related to the conditions of the athletes, consider their physical and psychological aspects separately. This prospective cohort study aimed to assess whether physical and psychological factors synergistically increase the risk of injury among Japanese footballers by examining field-based measurements and online surveys. A total of 94 footballers were followed up during the football season. Eight factors comprising four physical (current injury, pain awareness, functional movements, and ankle instability) and four psychological factors (catastrophic thoughts about pain, sleepiness awareness, sleep disorder, as well as anxiety and depression) were examined. An increased risk of injury was observed when the physical injury was associated with emotional reactions, defined as psychological factors. This study confirms the findings of previous reports focusing on psychological factors and shows that encouraging collegiate athletes to seek treatment for such concerns can be extremely effective. It is, therefore, important to adopt programs that communicate the importance of collaborative and interdisciplinary treatment approaches to collegiate athletes, sports physicians, and administrative staff to provide comprehensive treatment for collegiate athletes.

This study aimed to develop regression equations to estimate running velocity of maximal oxygen uptake (vVO₂max) and onset of blood lactate accumulation (vOBLA) from a 3200-m run time using a soccer pitch. Forty-four Japanese male junior youth soccer players from a team in the Japan Professional Football League First Division (J1 League) participated in this experiment. In the laboratory, vVO₂max and vOBLA were measured using an incremental load test, while the 3200-m run time was measured on the soccer pitch. Structural equation modeling was applied to analyze the sequential causal structure and latent growth curve models of aerobic running capability development during soccer training. A regression equation (1) utilized the 3200-m run time (s) as the independent variable (x) and vVO₂max (km/h) as the dependent variable (y), resulting in the equation y=-0.02461x+36.60 (r²=0.564). The regression equation (2) utilized the 3200-m run time (s) as the independent variable (x) and vOBLA (km/h) as the dependent variable (y), resulting in the equation y=-0.01833x+29.30 (r²=0.541). The coefficient of determination (r²) for the regression equations exceeded 0.5. We successfully developed to estimate vVO₂max and vOBLA from a 3200-m run time in Japanese male junior youth soccer players.

At the beginning of the 2023 season, the Japanese Professional Football League (J-League) changed the speed criterion of sprinting from > 24 km/h to > 25 km/h (SP24 and SP25). This study aimed to determine the interchangeability of the SP24 and SP25 in a professional football match using 10- Hz positioning information from a global navigation satellite system. Of the 70 match files that were randomly selected, 66 satisfied the inclusion criteria for the final study. SP24 and SP25 were defined as running for > 1 s with a speed of at least 24 and 25 km/h, respectively. The number of instances of SP25 was significantly lesser than that of SP24 (p < 0.01), and the relative deviation was -25.68 ± 20.74 %. The lower and upper agreement limits were -5.32 and 1.64 n/match, respectively. A significant relationship was observed between the deviation and average value (r = -0.681, p < 0.01). Additionally, SP25 was significantly shorter in time and distance than was SP24 (p < 0.001). Our findings suggest that the SP profiles from the 2023 season (SP25) were not interchangeable with those from previous seasons of the J-League (SP24).

The details about relative age effect in Japanese male professional soccer players are not readily at hand. This study clarifies the recent trend of relative age effect in Japanese male professional soccer players using data from 2011 season to 2020 season. Our study had two analytical perspectives: In analysis 1, we examined the relative age effect in all Japanese male professional soccer players in each season from 2011 to 2020; in analysis 2, we studied the relative age effect in Japanese male professional soccer players who newly registered in the league in each season from 2012 to 2020. There were significant differences in the proportion of Q1 (April–June) –Q4 (January–March) of every season in analysis 1, and Q1/Q4 were 2.0- 2.3. Effect sizes (ω) were 0.23–0.29. There were significant differences in the proportion of Q1–Q4 of every season except for the 2013 season in analysis 2 and Q1/Q4 were 1.6–3.2. Effect sizes (ω) were 0.22–0.46. In conclusion, relative age effect in Japanese male professional players is continuously present in recent years and is equally present in young soccer players who recently registered for the first time. The strength of the relative age effects does not demonstrably change from the 2011 to the 2020 season because effect size did not consistently increase or decrease.

Currently, the most commonly used goalkeeping ability metric for goalkeepers is Save percentage (SV%); however, SV% is not an effective evaluation index of goalkeeping ability because it does not account for goalkeeping-related difficulty. Recently, a regression equation was constructed to predict the probability of goalkeeping failure; with this equation, it has been possible to quantify goalkeeping-related difficulty. The purpose of the present study was to develop a new goalkeeping ability index for goalkeepers, which would take into account the degree of goalkeeping-related difficulty using a logistic regression model for predicting the probability of goalkeeping failure. To this end, we propose two new evaluation metrics: Saving Indicator (SVI) and Saving Score (SVS). Using SVI, SVS, and SV%, we evaluated the performance of goalkeepers who competed in the 2018 FIFA World Cup in Russia. Comparison of the three evaluation indexes revealed that both SVI and SVS considered the degree of goalkeeping-related difficulty but SV% did not. In future research, it will be necessary to evaluate an entire football tournament and season using SVI and SVS and to consider in detail the characteristics of each new goalkeeping evaluation index and how to specifically apply them.