Maturation-specific enhancements in lower extremity explosive strength following plyometric training in adolescent soccer players: A systematic review and meta-analysis.

Background: For adolescent soccer players, good sprinting and jumping abilities are crucial for their athletic performance. The application of plyometric training on boosting explosive strength in adolescent soccer players is contingent upon the maturation phase, which can mediate the training-induced adaptations. Purpose: This systematic review and meta-analysis aim to explore the maturation effect of plyometric training on the lower limb explosive power of adolescent soccer players, with vertical countermovement jump (CMJ) and 20-m sprint as the main outcome indicators. Methods: An extensive search of the literature was carried out on various databases including PubMed, Web of Science, Scopus, ProQuest, and the China National Knowledge Infrastructure (CNKI), covering the time period from the establishment of each database to February 6, 2023. The search was conducted using English keywords such as 'Plyometric,' 'Adolescent,' 'football,' and 'Explosive strength.' This study utilized the Cochrane risk of bias assessment tool to conduct a standardized quality evaluation of all the included literature. Additionally, the Review Manager 5.4 software was employed to perform data analysis on all the extracted data. Results: A total of 17 studies involving 681 adolescent soccer players aged 10 to 19 were included. Plyometric training significantly improved CMJ performance across different maturation stages, especially in the post-peak height velocity stage (POST-PHV) [MD = 4.35, 95 % CI (2.11, 6.59), P < 0.01, I2 = 60 %]. The pre-peak height velocity stage (PRE-PHV) showed the next best improvement [MD = 3.00, 95 % CI (1.63, 4.37)], while the middle-peak height velocity stage (MID-PHV) showed the least improvement [MD = 2.79, 95 % CI (1.16, 4.41), P < 0.01, I2 = 49 %]. However, improvements in 20 m sprint ability were only observed in the PRE-PHV [MD = -0.06, 95 % CI (-0.12, 0), P < 0.01, I2 = 0 %] and MID-PHV [MD = -0.18, 95 % CI (-0.27, -0.08), P < 0.01, I2 = 0 %] stages. Conclusion: Plyometric training serves as a potent strategy for boosting the lower limb explosive strength of adolescent soccer players, and the training effect is closely related to the players' biological maturity. Considering biological maturity is a key aspect that this study deems essential for the formulation of effective training programs for these adolescent players.

What the Eyes Don't See: An Objective Assessment of Players' Contribution to Team Success in Men's Rugby League.

Purpose: This study addresses the lack of objective player-based metrics in men's rugby league by introducing a comprehensive set of novel performance metrics designed to quantify a player's overall contribution to team success. Methods: Player match performance data were captured by Stats Perform for every National Rugby League season from 2018 until 2022; a total of five seasons. The dataset was divided into offensive and defensive variables and further split according to player position. Five machine learning algorithms (Principal Component Regression, Lasso Regression, Random Forest, Regression Tree, and Extreme Gradient Boost) were considered in the analysis, which ultimately generated Wins Created and Losses Created for offensive and defensive performance, respectively. These two metrics were combined to create a final metric of Net Wins Added. The validity of these player performance metrics against traditional objective and subjective measures of performance in rugby league were evaluated. Results: The metrics correctly predicted the winner of 80.9% of matches, as well as predicting the number of team wins per season with an RMSE of 1.9. The metrics displayed moderate agreement (Gwet AC1 = 0.505) when predicting team of the year award recipients. When predicting State of Origin selection, the metrics displayed moderate agreement for New South Wales (0.450) and substantial agreement for Queensland (0.652). Conclusion: The development and validation of these objective player performance metrics represent significant potential to enhance talent evaluation and player recruitment.

Systematic review and meta-analysis of Chinese coach leadership and athlete satisfaction and cohesion.

Introduction: This meta-analysis investigates the relationship between coach leadership behaviors and athlete satisfaction and group cohesion within the realm of Chinese sports. The study also explores player sex and player classification as potential moderating variables. The primary focus is on evaluating the impact of coaching behaviors, as measured by the Leadership Scale for Sports, on athlete satisfaction and group cohesion. Methods: Standard literature searches from China National Knowledge Infrastructure and Wanfang academic databases produced 26 studies encompassing a total of 319 effect sizes and a participant pool of 7,121 athletes across various sports. Results: Using the Comprehensive Meta-Analysis (CMA) to examine relevant data, results reveal a moderate and positive association between coach leadership and athlete satisfaction (ES = 0.412). Specifically, training and instruction (ES = 0.531), positive feedback (ES = 0.526), social support, and democratic decision-making exhibit positive effects, while autocratic behavior demonstrates a marginal positive effect. Similarly, a moderate positive relationship is identified between coach leadership and overall group cohesion (ES = 0.275), with training and instruction (ES = 0.396), social support (ES = 0.356), positive feedback, and democratic behavior positively influencing cohesion. Conversely, autocratic behavior has a small negative impact on cohesion. Furthermore, female athletes (ES = 0.603) and professional players (ES = 0.544) display stronger positive associations between coach leadership and satisfaction. Conclusion: These findings highlight the significance of diverse coaching behaviors aligned with player characteristics for fostering positive athlete satisfaction and group cohesion within the Chinese sports context, offering valuable guidance to Chinese coaches aiming to enhance their coaching strategies.

Player selection in football by integrated SWARA-VIKOR methods under fuzzy environment.

This study aims to provide an objective evaluation and selection of the most suitable players for the Turkish National Football Team by using multi-criteria decision-making methods, specifically Stepwise Weight Assessment Ratio Analysis (SWARA) and VIsekriterijumsko KOmpromisno Rangiranje (VIKOR) based on neutrosophic numbers. In the initial step of the study, the important criteria for player selection were determined, and a total of 21 and 26 criteria were identified for goalkeeper and players, respectively. Agility, reflexes and jumping ability are very important for goalkeeper whereas marking, passing ability, agility, dribbling, and footwork are the most important criteria for players. The performances of the players were evaluated due to these criteria and finally the Turkish National Football Team was established scientifically because of the best player selection. This decision-making process will be more beneficial in making more informed and effective decisions in the national team's player selection process. The success of the team can be improved by providing an objective and systematic player selection approach.

Morphologic changes in the posterior glenoid rim is independently associated with rotator cuff impingement in baseball players.

Background: The morphological changes in the posterior glenoid rim are unknown in relation to the area of rotator cuff tendons pinched within the glenohumeral joint in the throwing shoulders of baseball players. Therefore, this study aimed to clarify whether these changes are associated with the area of impingement in baseball players. Methods: Overall, 25 asymptomatic male college baseball players (average age19.8 years, 11.6 years of competing, and 50 shoulders) participated in this study. The area of impingement (AOI, mm2) and posterior glenohumeral distance (PGHD, mm) were measured using magnetic resonance imaging to quantitatively assess the impingement area of the rotator cuff tendon within the glenohumeral joint and the morphologic change in the posterior glenoid rim. These magnetic resonance imaging assessments were measured at 90° shoulder abduction with 90° and 100° external rotation. Multiple linear regression analysis was performed to determine whether AOI is predicted by PGHD. Findings: Multiple linear regression analysis showed that the PGHD was a predictor of the AOI at external rotation 90° (ß-coefficient = 0.738, R2 = 0.77, P < 0.001) and external rotation 100° position (ß-coefficient = 0.879, R2 = 0.76, P < 0.001). Interpretation: This study found that the area of impingement was associated with posterior glenohumeral distance. Therefore, these findings may indicate that complex shoulder joint morphologic changes result in a disabled throwing shoulder.

Kinematics characteristics of key point of interest during tennis serve among tennis players: a systematic review and meta-analysis.

The objective of this systematic review and meta-analysis was to provide an overview of kinematic parameters associated with key points of interest in the tennis serve. The research was conducted according to the PRISMA guideline without date restriction. Google scholar, Science Direct, PubMed/Medline, Mendeley, and Science.gov databases were scanned to find relevant studies. Only English peer-review original article focused on joint body angles at trophy position, racket low point and ball impact were retained. The review, quality appraisal, and data extraction from selected studies were performed independently by two reviewers. A meta-analysis was carried out on the most studied joint parameters. Among the 2,844 records identified, 27 articles were included. The wide variety of methods used required data homogenization for comparison purposes. Trunk inclination (25.0 ± 7.1°) and front knee flexion (64.5 ± 9.7°) were the most studied parameters for trophy position. Shoulder lateral rotation (130.1 ± 26.5°) was systematically evaluated for racket low point. At ball impact, shoulder elevation (110.7 ± 16.9°) and elbow flexion (30.1 ± 15.9°) were the most considered joint angles. The systematic review revealed that many kinematic parameters were not quantified at the various key points of interest. Knowledge of the kinematics is essential for understanding the gesture, implementing training methods, and improving the performance.

Bayes-xG: player and position correction on expected goals (xG) using Bayesian hierarchical approach.

This study employs Bayesian methodologies to explore the influence of player or positional factors in predicting the probability of a shot resulting in a goal, measured by the expected goals (xG) metric. Utilising publicly available data from StatsBomb, Bayesian hierarchical logistic regressions are constructed, analysing approximately 10,000 shots from the English Premier League (for the years of 2003 and 2015) to ascertain whether positional or player-level effects impact xG. The findings reveal positional effects in a basic model that includes only distance to goal and shot angle as predictors, highlighting that strikers and attacking midfielders exhibit a higher likelihood of scoring. However, these effects diminish when more informative predictors are introduced. Nevertheless, even with additional predictors, player-level effects persist, indicating that certain players possess notable positive or negative xG adjustments, influencing their likelihood of scoring a given chance. The study extends its analysis to data from Spain's La Liga ( ≈ 20 K shots from 1973 and 2004 to 2020) and Germany's Bundesliga ( ≈ 7.5 K shots from 2015), yielding comparable results. Additionally, the paper assesses the impact of prior distribution choices on outcomes, concluding that the priors employed in the models provide sound results but could be refined to enhance sampling efficiency for constructing more complex and extensive models feasibly.

Is Workload Associated With Oblique Injuries in Professional Baseball Players?

Background: Oblique strains have become a common injury among professional baseball players. The influence of player workload on oblique strains remains unknown. Purpose/Hypothesis: To determine whether workload is a risk factor for oblique strains in professional baseball players. We hypothesized that fewer days of rest, more innings pitched/fielded per game, and more batters faced/plate appearances per game would significantly increase a player's risk of sustaining an oblique strain. Study Design: Case-control study; Level of evidence, 3. Methods: All professional baseball players who sustained an oblique strain between 2011 and 2017 were identified using the Major League Baseball Health and Injury Tracking System. A separate dataset of player usage-days of rest per game, innings pitched or fielded per game, and batters faced or plate appearances per game-was used to determine the workload. We compared these usage variables between player games ≤2, ≤6, ≤12, and >12 weeks before a documented oblique strain with player games from a control group of players with no oblique strains. In a paired analysis, we compared acute (player games ≤2, ≤6, and ≤12 weeks preinjury) versus chronic (player games >12 weeks preinjury) workloads. Results: There were 311 oblique strains in pitchers and 392 oblique strains in position players during the study period. In pitchers, more innings pitched and more batters faced were associated with a subsequent oblique strain (P < .001 for all). In position players, fewer days of rest, more innings fielded, and more plate appearances were associated with a subsequent oblique strain (P < .001 for all). Pitchers who pitched ≥7 innings per game had a 2.4-fold (95% CI, 1.4-4.9) increased risk of subsequent oblique strain compared with those who pitched 1 inning per game. The percentage of position players with a subsequent oblique strain increased by 2.1-fold (95% CI, 1.3-3.5) with >4 plate appearances compared with 1 plate appearance per game. Conclusion: Our analysis demonstrated that workload was associated with an increased risk of sustaining an oblique injury in professional baseball players. High workload over time was more predictive of oblique strains compared to acute increases over chronic baseline workload.

Analysis of player speed and angle toward the ball in soccer.

The study analyzes how the magnitude and angle of the speed of soccer players change according to the distance to the ball and the phases of the game, namely the defensive and attacking phases. We observed how the role played in the team (goalkeeper, defender, midfielder, or forward) strongly determines the speed pattern of players. As a general trend, the speed's modulus is incremented as their position is closer to the ball, however, it is slightly decreased when arriving at it. Next, we studied how the angle of the speed with the direction to the ball is related to the distance to the ball and the game phases. We observed that, during the defensive phase, goalkeepers are the players that run more parallel to the ball, while forwards are the ones running more directly to the ball position. Importantly, this behavior changes dramatically during the attacking phase. Finally, we show how the proposed methodology can be used to analyze the speed-angle patterns of specific players to understand better how they move on the pitch according to the distance to the ball.

Evaluation of muscular and functional inter-limb asymmetries during mid-season in young male soccer athletes.

BACKGROUND: To identify inter-limb asymmetries through the knee's muscular and lower limb functional performance in young male soccer athletes. METHODS: Twenty male soccer athletes aged 17 to 19 from an under-20 team performed isokinetic tests at 60°/s., 120°/s., 180°/s., and 240°/s. To assess the knee extensors and flexors muscles and functional tests (hop tests and Y-balance test). RESULTS: There were no significant differences between the dominant limb (DL) and non-dominant limb (NDL) in the knee extensors and flexors peak torque and hamstrings (H)/quadriceps(Q) conventional ratio. Moreover, no angular velocities observed inter-limb asymmetries seen by values higher than 10% in the isokinetic parameters. However, the H/Q conventional ratio shows borderline values in low angular velocities (60°/s. and 120°/s.). No significant changes were observed in the functional test performance between the DL and NDL. Furthermore, we did not see inter-limb asymmetries in both hop and Y-balance tests. On the contrary, the anterior distance reached was lower than found in the literature, and the composite score of the Y-balance test demonstrated values below the normative (>94%). CONCLUSION: The data demonstrated that soccer athletes have muscular and functional inter-limb symmetry. However, they tend to have knee muscle imbalance in low velocities and dynamic balance deficits that might increase the risk of musculoskeletal injury.

Developing the Physical Performance in Youth Soccer: Short-Term Effect of Dynamic-Ecological versus Traditional Training Approach for Sub-Elite U13 Players-An Ecological Exploratory Cluster Randomised Trial.

Currently, research in youth soccer consists of methodological choices that can raise activity volumes and exercise intensity to promote proper training for youth soccer demands. Therefore, the present cluster randomised trial aims to evaluate the effects of the dynamic-ecological approach on the physical performance parameters compared with a traditional one in a group of sub-elite U13 players. Thirty-five male children (age 12.16 ± 0.55 years; weight 45.59 ± 7.15 kg; height 145.5 ± 4.2 cm; BMI 15.8 ± 2.1 kg·m-2) were recruited for this trial from two teams belonging to sub-elite soccer schools and randomly assigned to a dynamic-ecological approach (DEA) or a traditional training (TTG) group. The training program lasted six weeks and consisted of 18 training sessions of 90 min each (3 sessions per week). The sample was evaluated by the standing long jump (SLJ), hop test (HT), 10 m sprint (10 m), 10 × 5 m shuttle run test (SRT), and leg raise test (LR). The DEA group showed significantly higher results in the SLJ (p < 0.001), HT left leg (p < 0.001), 10 m sprint (p < 0.001), and SRT (p < 0.001). In conclusion, the dynamic-ecological approach provides higher performance adaptations. Therefore, this approach can be considered a suitable method to optimise pre-pubertal player training, mainly when no fitness or strength coach is available.

The Mental Game of Golf: Understanding Relationships Between Self-Efficacy, Fear of Failure, Competitive State Anxiety, and Flow.

Our purpose in this study was to investigate the relationship between self-efficacy, fear of failure, competitive state anxiety, and flow among elite golfers. We surveyed 375 elite golfers (N = 375; male = 187, female = 188) who were registered with the Korean Sports and Olympic Committee, and we analyzed their survey responses using descriptive statistics, confirmatory factor analysis, correlation analysis, and structural equation modelling. As expected, we found golf self-efficacy (GSE) to be significantly related to fear of failure (FOF). We also found FOF and competitive state anxiety (CSA) significantly related to flow. Finally, we verified a suspected hierarchical or mediating effect in these relationships such that we verified predictive relationships of flow as follows: GSE→FOF→CSA→Flow. These golfers' self-efficacy had a buffering effect of lowering their FOF and CSA in the pathway toward flow. A suggested implication of these findings is that to enhance a golfer's performance by minimizing interfering psychological factors, it is essential to boost their self-efficacy.

Assessing the individual relationships between physical test improvements and external load match parameters in male professional football players-a brief report.

Purpose: This study aimed to explore whether a meaningful improvement in physical performance following an in-season strength training intervention can be related to external load match parameters at an individual level in professional male football players. Methods: Eight male professional football players (25.4 ± 3.1 years, 184.1 ± 3.4 cm, 79.3 ± 2.2 kg) completed a 10-week strength intervention period in addition to football-specific training and matches. Commonly used physical and external load measures were assessed before and after intervention. Physical performance improvements had to exceed the measurement's typical error and the smallest worthwhile difference (SWD) to be considered meaningful. External load match parameters were assessed before and after the intervention period using SWD and non-overlap of all pairs (NAP) analysis. A Bayesian pairwise correlation analysis was performed to evaluate relationships between changes in physical performance and external load match parameters. Results: Three players displayed meaningful improvements in two to five physical performance measures. However, positive changes exceeding the SWD and positive effects in NAP results were observed for all players in external load match parameters. Kendall's tau correlation analysis showed evidence (base factor >3) for only one correlation (maximum speed - decelerations, τ = -0.62) between the changes in physical performance and external load measures, while the remaining comparisons exhibited no relation. Conclusions: The findings suggest that improvements in physical performance may not necessarily translate to improvements in external load match parameters. Further research, with larger sample sizes, is needed to understand potential mechanisms between acute and chronic physical performance changes and football external load parameters during training and matches.

The Impact of Praise on Cooperative Behavior in Three-Player Public Goods Games and Its Gender Differences.

Previous research has primarily focused on static factors influencing cooperative behavior in social dilemmas, with less attention given to dynamic factors within group social interactions, such as positive feedback received during interactions, i.e., praise. This study, through a between-subjects online experiment with a single-factor, two-level design (praise: public praise/no praise), investigates the impact of praise on cooperative behavior changes across two rounds of a three-player public goods problem. Results revealed the following: (1) A positive correlation between individuals' contributions across two rounds and a negative correlation with the number of correct answers in rule comprehension questions were evident; for men, a correlation between rule comprehension and first-round contributions was observed. (2) Multilevel model results showed that praise, role, and rule comprehension significantly positively affected contribution changes across two rounds; gender did not significantly affect contribution changes. Specifically, under public-praise conditions, contribution changes were greater. Publicly praised individuals showed positive or negative behavior changes, while those not praised in the same group showed positive changes. Men contributed significantly more in the first round than women, with no gender difference found in contribution changes. Rule comprehension positively predicted contribution changes, indicating that more correct answers led to greater positive changes in contributions. These results not only support the inferential social learning perspective, suggesting that through praise, individuals can infer external world perceptions and self-evaluations, affecting both the praised (positively or negatively) and positively influencing non-praised individuals in the same group, but also provide a theoretical basis and intervention strategies for team and organizational management in groups.

Beyond the Jump: A Scoping Review of External Training Load Metrics in Volleyball.

CONTEXT: Volleyball is a complex sport involving multifaceted movements and high-velocity actions, leading to diverse external training loads (ETLs) that have profound implications for player performance and injury risk. OBJECTIVE: To provide a comprehensive overview of the measurement of ETL in volleyball, identify gaps in current understanding, and offer valuable insights for stakeholders in the field. DATA SOURCES: The literature search was conducted across the following electronic databases: PubMed/Medline, Scopus, Web of Science, and SPORTDiscus. STUDY SELECTION: Studies were selected based on their relevance to the measurement of ETL in volleyball. STUDY DESIGN: A scoping review methodology was chosen to map and summarize the broad body of literature related to ETL measurement in volleyball. LEVEL OF EVIDENCE: Level 4. DATA EXTRACTION: Data related to ETL measurements in volleyball were extracted and analyzed from the selected studies, focusing on metrics utilized, player positions examined, and technologies employed. RESULTS: A total of 18 studies related to ETL in volleyball were identified and examined for this review. Despite the importance of sagittal plane movements in volleyball, the review identified a substantial research gap regarding ETL measurements beyond this plane, as well as a lack of focus on the unique demands of different player positions like the liberos. The use of technologies such as inertial measurement units was prevalent, but more comprehensive measurement methods are needed. CONCLUSION: There is a critical need for diversified ETL metrics in volleyball, extending beyond the conventional sagittal plane measurements. The findings highlight a substantial research gap in addressing the unique demands of different player positions, notably the liberos. This study underscores the importance of incorporating multiplanar movement data, player-specific roles, and advanced measurement technologies to develop more tailored training programs and injury prevention strategies.