On properties of one functional used in software constructions for solving differential games

Nonlinear differential game (DG) is investigated; relaxations of the game problem of guidance are investigated also. The variant of the program iterations method realized in the space of position functions and delivering in limit the value function of the minimax-maximin DG for special functionals of a trajectory is considered. For every game position, this limit function realizes the least size of the target set neighborhood for which, under proportional weakening of phase constraints, the player interested in a guidance yet guarantees its realization. Properties of above-mentioned functionals and limit function are investigated. In particular, sufficient conditions for realization of values of given function under fulfilment of finite iteration number are obtained.

Anthropometric Profile of FIVB Volleyball Girls' U18 World Championship Volleyball Players According to the Playing Position- World Championship 2017

Identifying the anthropometric characters of adolescent elite players may be useful in developing the recognition of volleyball talents and key physical abilities needed to perform at a high level. The purpose of this study was to describe anthropometric characteristics, including height, weight, body mass index (BMI), spike height, and block height in elite volleyball youth players participating in the 2017 FIVB Volleyball Girls' U18 World Championship. Also, comparisons of these parameters were evaluated based on individual game position (libero, setter, middle blocker, outside hitter, opposite), team continent, and team rank. The variables studied in this study were extracted from the list of players registered on the website of the International Volleyball Federation (FIVB) and included 240 players of 20 teams. The results of one-way ANOVA showed that players in the G1 group (rank 1 to 4) had higher height, weight, spike height, and block height than other groups (rank 5 to 20). Also, the middle blockers had the tallest height (185.9 cm), weight (71.4 kg), spike height (294.5 cm) and block height (282.7 cm). This study presents anthropometric data that show different levels of success for elite girls' volleyball players in the 2017 championship. This information should serve as a reference for average body height, weight, BMI, spike height, and block height for identifying athletic talents for various positions in volleyball.

Epidemiology of Injuries in First Division Spanish Women’s Soccer Players

The epidemiology of injuries in female soccer has been studied extensively in several national leagues. Even so, data on the first division Spanish league are limited. The objective of this study was to describe the epidemiology of the first division of the Spanish Women’s Soccer League and to analyze data in relation to game position, circumstance, or the moment of injury. Fifteen teams and 123 players participated in the study. Players’ characteristics and their injuries (location, type, diagnosis, circumstance, and moment) were collected. Injuries were described by their frequencies (number and percentage) and incidence rates (IR) with 95% confidence intervals (CIs). Lower limb injuries accounted for 86.8% of total injuries. Anterior cruciate ligament (ACL) and meniscus injuries occurred in totality in non-contact circumstance (0.35/1000 h; 95% CI, 0.18 to 0.62 and 0.23/1000 h; 95% CI, 0.10 to 0.45, respectively). Match injury IRs (19.02/1000 h; 95% CI, 14.89 to 23.97) were significantly higher than training (1.70/1000 h; 95% CI, 1.27 to 2.22). As a conclusion, structures such as the ACL or meniscus are most commonly injured in the non-contact circumstance in the first division of the Spanish Women’s Soccer League. In addition, match situations involve a greater risk of injury than training, increasing the risk to the ankle and knee injuries as the season progresses.

Anthropometric Profile and Physical Fitness Performance Comparison by Game Position in the Chile Women’s Senior National Football Team

The aim of this study was to explore the anthropometric profile and evaluate physical fitness variables of the members of the Chile women’s national football team based on their playing positions. Fifty football players participated in this study, which was carried out during the period of training for the France 2019 Women’s World Cup and the Japan 2020 Olympic Games. Body composition and physical condition (muscular strength, sprint, agility, and aerobic fitness) were assessed. The goalkeepers showed greater weight (p < 0.001), height (p = 0.002), and %Fat (p = 0.010) compared to the rest of the playing positions. There were also differences between positions in relative strength (RS) (p = 0.001), running speed at 10 and 30 m (T10 and T30, respectively), agility (AGI) (p < 0.001), and yo-yo test (MYYR1) (p < 0.001). RS, T10, T30, and countermovement jump (CMJ) were significantly correlated (p ≤ 0.05) with anthropometric variables (p ≤ 0.05). MYYR1 was also significantly correlated with anthropometric variables (p ≤ 0.05). In conclusion, goalkeepers show greater weight and height, as well as worse results in MYYR1, AGI, T10, T30, and RS compared to the rest of the players. Forwards present better performance in running speed and agility. Better performance in physical condition is associated with better body composition values (greater muscle mass and lower fat mass). Greater relative strength indicates greater performance in explosive actions. Therefore, to meet the demands of high competition, it is important to establish ideal profiles in anthropometry and physical condition variables based on the playing position.

Injury profile of a soccer player training center: An epidemiological study

Objective: To carry out an epidemiological analysis characterizing the type and location of the injury, severity based on recovery time, game position, and injury for hours of exposure. Methods: Data collection was carried out in the sub 15, sub 17, and sub 20 categories and verified records made by the medical team of the club, which was trained to use the F-MARC form (a form of the medical research center of the International Football Federation - FIFA) at the beginning of the season. To perform the data analysis, the GraphPad Prism software was used. All variables were analyzed using the Kolmogorov-Smirnov test. Results: In relation to the 129 athletes monitored during the season, 62 athletes presented some injury during the season, presenting 42.2 injuries for every 1000 hours of play, the Sub 15 category was the one with the highest incidence of injury, followed by the Sub17 and U20. The average time of leave after injury was 3.65 ± 4.2 weeks, the Defenders were the ones with the highest injury rate. There were 27 articular injuries (43.54%), 25 muscle injuries (40.32%), 9 bone injuries (15.41%), and one pathological injury (1.61%), and the most affected regions were ankle and knee. Conclusion: It is concluded that the moment of the game is the moment when the greatest number of injuries occurs, having a greater incidence in the athletes of the category Sub 15, the Defenders suffered more injuries and the Lower Limbs were more affected, mainly by articular traumas.

Evolution of Physical Fitness in Formative Female Basketball Players: A Case Study

Over the last few years, team sports increased the amount of physical demand and its importance. Therefore, work related to physical fitness and its assessment is essential to achieving success. However, there are few studies on this subject at the formative stage. The purpose of this study was then to analyze the physical fitness of an under-18 (U18) women’s team divided by game positions. In addition, physical fitness at different times of the season was characterized to identify differences and determine its evolution. To assess physical fitness, tests of aerobic and anaerobic capacities, lower body strength, centripetal force, agility and speed were carried out as designed in the SBAFIT battery. Each player was equipped with an inertial microtechnology device for the collection of data. This research is classified as empirical, with quasi-experimental methodology. The results showed significant differences in variables of the test of aerobic and anaerobic capacities, speed, agility (generic and specific), and centripetal force (right) based on game position and the moment of the season. The results also showed the importance of the specific physical aspect in relation to an optimal improvement in physical fitness, since training sessions and competition do not allow all players to improve equally or efficiently.

Video Analysis of Concussion Exposures in a National Collegiate Athletic Association Division I Football Team

Background: Research into improving player safety of sport-related concussion (SRC) in American football has been an ongoing endeavor. In an attempt to better understand the incidence of SRCs in American football, research has focused on the characteristics of SRC during gameplay. Determining SRC specifics and assessing them quantitatively can help identify high-risk scenarios and predict exposure risk. Purpose: To identify and assess the incidence of SRCs in a National Collegiate Athletic Association football team by comparing field location, player positions, collision partners, and player cues. Study Design: Descriptive epidemiology study. Methods: We used physician sideline reports of diagnosed concussions from a Division I football team from September 2010 to December 2018. Game videos were analyzed to identify the field location where the SRC occurred, collision partner, and player behavior postconcussion. The incidence of in-game SRCs by position was also assessed. We used the “words of estimative probability” model to categorize each concussion as certain, almost certain, probable, or even on the basis of our confidence in identifying them using game film. Results: This study examined 44 SRCs that occurred over 9 seasons. The SRC incidence was significantly higher in the middle defense (5-20 yards from the line of scrimmage) compared with all other field locations (relative risk, 2.46; 95% CI, 1.14-5.29; P < .05). In-game collision partners were most commonly defensive backs. The most common player cue was a hand to helmet/face mask. The positions with the highest SRC incidence by athlete-exposure, game position, and position play belonged to the defensive backs, wide receivers, and running backs. Conclusion: The middle defense had a significantly higher incidence of SRCs than all other field locations. We pose a new method to categorize concussions during video analysis by using words of estimative probability. Knowledge of SRC gameplay characteristics can potentially guide the medical staff and medical observer to better identify them.