Science & medicine in football最新文献

Purpose: The aim of this study was to survey Major League Soccer stakeholders' attitudes and perspectives on the youth-to-senior transition with a particular interest in the league's evolving club structures, specifically the reserve team and youth academy entities. The survey assessed various stakeholders' views on clubs' organisational aims and structure, the capabilities of club entities to prepare players for the first team, and the transition process to the first team within MLS.

Methods: A total of 80 participants working in various 'player operation' roles for MLS clubs in the United States and Canada voluntarily completed the online survey.

Results: The predominant aim for both reserve teams and academies in MLS is to develop players for the first team. The organisational structure and governance of reserve teams are varied across the league, but an overarching feature is their function as a development team. When players are transitioning, communication between staff may or may not be clear and effective. Finally, for players within an MLS club's talent pathway, a variety of support strategies are made available during the transition into the first team, but psychological support in particular may be limited or unavailable.

Conclusion: Similar to European soccer, the aim of MLS reserve teams and youth academies is to develop first team players for the club. However, while players are transitioning into the first team, communication may or may not be clear and effective, and psychological support may be absent, which may impair player development initiatives.

There is concern that exposure to soccer headers may be associated with neurological sequelae. Training proper heading technique represents a coachable intervention that may reduce head acceleration exposure. The objective was to assess relationships between heading technique and head kinematics in female youth soccer players. Fourteen players (mean age = 14.4 years) wore instrumented mouthpieces during practices and games. Headers were reviewed by three raters to assign a technique score. Mixed models and LASSO regression evaluated associations of technique with peak linear acceleration (PLA), rotational acceleration (PRA), rotational velocity (PRV), and head impact power ratio (HIP Ratio) while adjusting for session type and ball delivery. Two hundred eighty-nine headers (n = 212 standing, n = 77 jumping) were analyzed. Technique score (p = 0.043) and the technique score - session type interaction (p = 0.004) were associated with PRA of standing headers, whereby each 10-unit increase in technique score was associated with an 8.6% decrease in PRA during games but a 5.1% increase in PRA during practices. Technique was not significantly associated with any other kinematic metrics; however, peak kinematics tended to decrease as technique score increased. LASSO regression identified back extension and shoulder/hip alignment as important predictors of peak kinematics. Additional research on heading technique and head acceleration is recommended.

The interest in sports performance analysis is rising and tracking data holds high potential for game analysis in team sports due to its accuracy and informative content. Together with machine learning approaches one can obtain deeper and more objective insights into the performance structure. In soccer, the analysis of the defense was neglected in comparison to the offense. Therefore, the aim of this study is to predict ball gains in defense using tracking data to identify tactical variables that drive defensive success. We evaluated tracking data of 153 games of German Bundesliga season 2020/21. With it, we derived player (defensive pressure, distance to the ball, & velocity) and team metrics (inter-line distances, numerical superiority, surface area, & spread) each containing a tactical idea. Afterwards, we trained supervised machine learning classifiers (logistic regression, XGBoost, & Random Forest Classifier) to predict successful (ball gain) vs. unsuccessful defensive plays (no ball gain). The expert-reduction-model (Random Forest Classifier with 16 features) showed the best and satisfying prediction performance (F1-Score (test) = 0.57). Analyzing the most important input features of this model, we are able to identify tactical principles of defensive play that appear to be related to gaining the ball: press the ball leading player, create numerical superiority in areas close to the ball (press short pass options), compact organization of defending team. Those principles are highly interesting for practitioners to gain valuable insights in the tactical behavior of soccer players that may be related to the success of defensive play.

Objectives: This study examines the training (age at club entry, hours in club practice, free play, other sports) and environmental characteristics (popularity, media coverage, school and parental support) influencing the development of female Swiss national team players in elite football over a three-decade period.

Methods: A retrospective questionnaire was completed by 84 participants, who were divided into three cohorts based on their first game with the Swiss national team (C1 = until 2000, n = 24; C2 = 2001-2010, n = 29; C3 = 2011-2022, n = 31). ANOVAs were employed to compare the cohorts regarding training and environmental variables.

Results: The findings demonstrate better perceived environmental conditions, stagnating volume of free play and other sports in childhood, decreasing age at club entry, and increasing club practice and total training volume across cohorts.

Conclusion: Practical implications highlight talent development avenues in unstructured settings during free time and in the micro-structure of club practice.

The concurrent validity and between-unit reliability of a foot-mounted inertial measurement unit (F-IMU) was investigated during linear and change of direction running drills. Sixteen individuals performed four repetitions of two drills (maximal acceleration and flying 10 m sprint) and five repetitions of a multi-directional movement protocol. Participants wore two F-IMUs (Playermaker) and 10 retro-reflective markers to allow for comparisons to the criterion system (Qualisys). Validity of the F-IMU derived velocity was assessed via root-mean-square error (RMSE), 95% limits of agreement (LoA) and mean difference with 95% confidence interval (CI). Between-unit reliability was assessed via intraclass correlation (ICC) with 90% CI and 95% LoA. The mean difference for instantaneous velocity for all participants and drills combined was -0.048 ± 0.581 m ∙ s^-1, the LoA were from -1.09 to -1.186 m ∙ s^-1 and RMSE was 0.583 m ∙ s^-1. The ICC ranged from 0.84 to 1, with LoA from -7.412 to 2.924 m ∙ s^-1. Differences were dependent on the reference speed, with the greatest absolute difference (-0.66 m ∙ s^-1) found at velocities above 7 m ∙ s^-1. Between-unit reliability of the F-IMU ranges from good to excellent for all locomotor characteristics. Playermaker has good agreement with 3D motion capture for velocity and good to excellent between-unit reliability.

The physical demands of elite sport are often monitored with the aim of making evidence-based decisions to enhance performance and reduce injury risk. However, there is limited evidence in rugby league of the monitoring practices and perspectives of practitioners. This study provides a cross-sectional view of practices and perspectives of rugby league practitioners engaged in monitoring the physical demands of training. Practitioners from the Super League, Championship and National Rugby League competitions completed an online survey. Questions related to the tools and measures used to monitor training, along with perceptions of monitoring effectiveness. 'Enhancing performance' was considered the most important factor for monitoring training demands with most practitioners using some form of time motion analysis (e.g., GPS) or accelerometers. Nearly all practitioners combined objective external measures of exercise intensity with subjective measures, of which RPE was most common. The monitoring parameters considered most useful were running metrics (high-speed running, total distance covered, and the number of accelerations). Findings suggest that current practices are mostly supported by evidence from research. There was a preference for internal load monitoring tools that are quick and simple, such as RPE. The extent to which training load was monitored was lesser in some Championship teams compared to those in the other competitions, which might be explained by discrepancies in funding and access to players.

Aims: The aim of this study was to investigate the associations between the early follicular (EF, i.e., menstruation), late follicular (LF), and middle luteal (ML) phases of the menstrual cycle and different factors that may influence football performance.

Methods: To this end, 11 eumenorrheic sub-elite female football players underwent field tests to assess sprint speed, lower extremity power, repeated sprint ability, velocity on change of direction, and technical skills at each cycle phase.

Results: Performance during the 15-m change of direction ability test, 15-m ball dribbling test, squat jump height, total sprint time [sum of 7 sprints] and decrement score [(mean sprint time/best sprint time × 100) - 100], maximum and mean heart rate, and perceived exertion did not significantly differ among menstrual cycle phases. Conversely, the linear sprint velocity over 10, 20, 30-m distances was decreased in EF vs LF (10-, 20- and 30-m) and in ML vs LF (10- and 20-m) (p < 0.05). The 40-m sprint velocity did not change in the different menstrual cycle phases.

Conclusion: Overall, our study suggests that sex hormone fluctuations during the menstrual cycle are not associated with vertical jump, velocity on change of direction, and repeated sprint ability, but may influence linear sprint velocity over short distances (10, 20, and 30 m).

There is a paucity of literature analyzing the impact of fatigue from actual competitive soccer match-play on measures of neuromuscular function and muscle damage markers in youth players. Aims The main purpose was to analyze the acute pre- and post-competitive soccer match-play changes in measures of landing mechanics, stretch-shortening cycle capability, physical performance, muscle damage, and match intensity. A secondary purpose was to explore whether the players' maturity status and chronological age were associated with post-soccer match-play responses. Methods Thirty-two male youth outfield soccer players from two chronological competition age groups (U14 and U16) were assessed pre-and post-competitive soccer match-play for 2D dynamic knee valgus at landing (DKV), leg stiffness, reactive strength index, 20 m sprint time, CMJ-Abalakov jump height, creatine kinase and urea activity and visual analogue scale for muscle soreness (VAS). Players' maturity status was also estimated using a previously validated regression equation. Results There were statistically significant (p < 0.05) post-competitive soccer match-play impairments in all measures of stretch-shortening cycle capability and muscle damage markers assessed irrespective of the age group. Likewise, significant post-match play alterations in landing mechanics (DKV of the dominant leg) and physical performance (sprint time and jump height) scores were documented for the U14 players. Significant interactions between maturity and landing mechanics and VAS responses to competitive soccer match-play were also found whereby more mature players demonstrated larger post-match changes. Conclusion The findings of this study suggest the existence of a negative influence of competitive match-play on neuromuscular function and muscle damage in youth soccer.

Objectives: This study aimed to examine the importance assigned to assessing and considering biological maturation in thematic areas of player development and provide an overview of current practices in German football academies regarding its consideration in training and competition.

Methods: An online survey was sent to 56 elite German football academies. A total of 46 responded to the questionnaire (82% response rate). Six participants provided incomplete information resulting in a total of 40 completed surveys in the period from March to May 2022.

Results: Only 20 of participants regularly carried out maturation assessments, despite 95% recognizing its importance for load management, 90% for player development, and 85% for injury prevention. There was no consistent approach to modifying training and competition formats based on maturity status, with a primary focus on gym-based sessions for load management.

Conclusion: The survey results highlight limited implementation of maturation assessment and training modification based on maturity status in German elite youth football academies. Despite recognizing the importance of load monitoring, reporting to parents, and long-term player development in considering biological maturation, practices are not widespread. The predominant use of the maturity offset method suggests an opportunity to improve accuracy by exploring alternative measurement methods and increasing assessment frequency. Moreover, a lack of established procedures for incorporating maturity status into training and competition exists, hindering comprehensive consideration of biological maturation and injury risk prevention. Further research is needed to understand the reasons for inconsistent approaches in maturation assessment and load modification during training and competition.

The aim of this study was to conduct a comprehensive scoping literature review to provide an overview of the current state of research within women's futsal. We searched four electronic databases (SPORTDiscus, PubMed, Scopus, and Web of Science) up to December 2023. Inclusion criteria comprised original research published in peer-reviewed journals, available in English, Spanish, or Portuguese. The focus was on studies investigating women in futsal, encompassing both players and those in leadership positions, regardless of their age or skill level. The analysis included the authorship (location), population characteristics (number of participants, level of play, and age), themes explored, and primary findings. A total of 692 records were found, but only 175 met the selection criteria. The results highlighted a recent attention in the scientific literature, with the first publications emerging in 2005 and a notable increase since 2016. Strength and Conditioning topics constituted the most frequently explored area, comprising 32% of the studies. Notably, no studies focusing on coaching or management aspects were identified. In terms of the participant population, most studies concentrated on high-level (33%) and senior (84%) players. Few studies have investigated practitioners with disabilities or women in other positions such as coaches or managers. Most of the studies were conducted by Brazilian researchers (60%), indicating the need for investigations in different socio-cultural contexts. The recent academic attention and the upcoming inaugural edition of the FIFA Futsal Women's World Cup^TM in 2025 reinforce the need for further studies on women's futsal. This review contributes by identifying the scientific gaps that can be explored by future investigations.