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'Tomorrow, Thursday, at 3pm, a football match will take place on the Plaine de Plainpalais, between 11 English from Lausanne and Geneva'. This brief notice, published in January 1869 in Le Journal de Genève, may be one of the earliest mentions in the area's press of a new ball game – football. Although the chronology of association football's 'cultural transfer' to Switzerland and the conditions that facilitated the game's introduction to the country are well-documented, the game's adoption by the local population remains under-researched. Based on extensive empirical research combining original archive materials and articles from contemporary generalist and sports newspapers, the present study explored the factors that led young men in Geneva and Lausanne to embrace a foreign game. It also examined two less-well studied aspects of the game's early history in Europe: the difficulty of finding places to play football in urban areas and the profiles of football's first leaders. The results extend previous research on the creation of the first football clubs (association or rugby) outside Great Britain and on the history of associations in Switzerland. [ABSTRACT FROM AUTHOR]

Highlights Female soccer players have been identified as presenting with low energy availability (LEA), though the prevalence of LEA may be overestimated given inaccuracies associated with self‐reporting dietary intakes. Accordingly, we aimed to quantify total daily energy expenditure (TDEE) via the doubly labelled water (DLW) method, energy intake (EI) and energy availability (EA). Adolescent female soccer players (n = 45; 16 ± 1 years) completed a 9–10 day ‘training camp’ representing their national team. Absolute and relative TDEE was 2683 ± 324 and 60 ± 7 kcal kg−1 fat free mass (FFM), respectively. Mean daily EI was lower (P < 0.01) when players self‐reported using the remote food photography method (RFPM) (2047 ± 383 kcal day−1) over a 3‐day period versus DLW derived EI estimates accounting for body mass (BM) changes (2545 ± 518 kcal day−1) over 7–8 days, representing a mean daily Δ of 499 ± 526 kcal day−1 and 22% error when using the RFPM. Estimated EA was different (P < 0.01) between methods (DLW: 48 ± 14 kcal kg−1 FFM, range: 22–82; RFPM: 37 ± 8 kcal kg−1 FFM, range: 22–54), such that prevalence of LEA (<30 kcal kg−1 FFM) was lower in DLW compared with RFPM (5% vs. 15%, respectively). Data demonstrate the potential to significantly underestimate EI when using self‐report methods. This approach can therefore cause a misrepresentation and an over‐prevalence of LEA, which is the underlying aetiology of ‘relative energy deficiency in sport’ (REDs). What is the central question of this study? Do self‐reported dietary intakes (via remote food photography method, RFPM) overestimate low energy availability (LEA) prevalence in female soccer players compared with energy intake evaluation from the doubly labelled water (DLW) method? What is the main finding and its importance? Estimated energy availability is greater with the DLW method compared with RFPM, such that the prevalence of LEA is greater when self‐reporting dietary intakes. Accordingly, data demonstrate the potential to misrepresent the prevalence of LEA, an underlying factor in the aetiology of ‘relative energy deficiency in sport’ (REDs). What is the central question of this study?Do self‐reported dietary intakes (via remote food photography method, RFPM) overestimate low energy availability (LEA) prevalence in female soccer players compared with energy intake evaluation from the doubly labelled water (DLW) method?What is the main finding and its importance?Estimated energy availability is greater with the DLW method compared with RFPM, such that the prevalence of LEA is greater when self‐reporting dietary intakes. Accordingly, data demonstrate the potential to misrepresent the prevalence of LEA, an underlying factor in the aetiology of ‘relative energy deficiency in sport’ (REDs). [ABSTRACT FROM AUTHOR]

Soccer biomechanics is a field that applies principles of mechanics to improve performance and reduce the risk of injury for soccer players. The purpose of this research is to perform a mapping review of the existing knowledge in the current literature, identify leading researchers and institutions, and explore emerging research topics. After conducting a mini literature review, a bibliometric analysis was carried out using the VOSviewer software. The data imported into VOSviewer was obtained from the Scopus database and included 951 records. The analysis performed included: (a) performance analysis to calculate the number of records per year and the authors with the most citations; (b) science mapping analysis (co-authorship, co-citation, and bibliographic coupling); and (c) clustering analysis through the co-occurrence analysis of author keywords. Our findings highlight a significant growth in research publications on soccer biomechanics over the past few decades, with a notable increase in the number of articles published in high-impact journals. Additionally, the clustering analysis resulted in seven clusters, with each cluster providing valuable insights into different aspects of soccer biomechanics, which clearly reflects the multifaceted nature of the field. [ABSTRACT FROM AUTHOR]

This research aims to evaluate the effectiveness of corner kicks, analyze the goal patterns resulting from corner kicks, and develop a model for the implementation of optimal corner kick strategies. The study used a descriptive retrospective design, and the data consisted of 455.898 corner kicks from matches played by 768 teams in 33 different leagues and an international tournament (UEFA). Six different models based on logistic regression were developed and analyzed. The results showed that more goals were scored from certain zones (1c, 2b, and 2c) inside the penalty area than from others (p < 0.001). According to logistic regression, zones 1c and 2c increased the probability of scoring a goal by 1.12 and 1.08 times, respectively, compared to other regions. In addition, it is noticeable that the probability of scoring from the zones varies considerably depending on the type of kick. Further results showed that there were no statistically significant differences between goals scored from in-swing and out-swing corners, but significant differences were found for the other types of corners. Finally, 3.1% of all corners resulted in goals, and 69% of those goals resulted in a draw or the team taking the lead in the match. For these reasons, it is important to develop new corner-kick strategies in order to score goals and win matches. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the positional dynamics in soccer small-sided games (SSGs) with either greater length (SSGlength) or width (SSGwidth) with official games. Twenty four Brazilian U-20 national-level players participated in six SSGs training sessions with two different SSG configurations: SSGlength (4v4, 40 m length and 26 m width) and SSGwidth (4v4, 26 m length and 40 m width). Positional dynamics variables were monitored and compared to official games. Linear mixed regression model was fitted using the situations as fixed effect, and, when appropriate, player and/or group as random effects. When compared to SSGlength and SSGwidth, official games showed a greater Relative Team Length, LPWratio, Spacial Exploration Index (SEI), and Strech Index, with a large or very large effect size. The SSGlength elicited higher values of Relative Team Width, LPWratio, and SEI when compared to SSGwidth. No significant differences were found between SSGlength and SSGwidth for Relative Team Length (small effect size), and SI (small effect size). Both group and player as random effects showed low variances. We concluded that the tactical behaviours during the 4v4 SSG differed substantially from the competitive tactical behaviour during the official games. In addition, changing the orientation of the playing field did not make the positional dynamics of the SSGs more similar to the official games. [ABSTRACT FROM AUTHOR]

Purpose: The aim of our study was to examine the effect of 16 weeks of strength training on anthropometric characteristics and jump height in semi-professional male players after a pre-season period. Methods: A parallel two-group, longitudinal (pre, post) design was used with physical tests performed before (preintervention) and after (postintervention) the 16-week intervention period. The soccer players were assigned and matched into two groups, an experimental group (EG) and a control group (CG), based on the team of which they were a part. Results: A two-way ANOVA was performed with group and time as factors. The results of a two-way ANOVA revealed no time×group interaction for body composition or jump height. Nevertheless, a paired measures t -test of weight, fat mass, lean mass, and countermovement jump (CMJ) test metrics (pre-post) and group (CG and EG) showed an improvement in all measures (p < 0.01). Discussion: The 16-week intervention program resulted in an improvement in the EG both at the level of body composition and in CMJ performance. Conclusions: Despite the benefits of the 16-week intervention program, a combination of training methods that includes power, agility-coordination, speed, and strength can enhance such improvements. It is important to take this strength-specific capacity into account in training, due to the importance outlined in the sport of soccer both for its transfer to both linear and COD sprints and specific strength skills and mainly to vertical jump. [ABSTRACT FROM AUTHOR]

It has recently been identified that the assessment of peak periods of activity better considers the stochastic nature of match-play and the influence that contextual factors have on these peak periods. Limited research exists attempting to link the tactical and physical aspects of performance, especially in female players. Therefore, the current study aimed to assess post-goal locomotor patterns and positional differences on peak match demands in elite female soccer players. Using 10 Hz global positioning system units, a total of 133 player match observations were recorded from 14 matches played by an elite Scottish women's professional soccer team. The total distance (TD), high-speed running distance (>18 km/h) (HSRD) and PlayerLoad™ (PL) were assessed for 1, 3 and 5-minute peak periods using a rolling epoch approach. Playing position and post-goal activity were used as modulating factors. Linear mixed models established a main effect for playing position for the HSRD at peak 1-minute (p <.001), 3-minute (p <.001) and 5-minute (p <.001) epochs. There were also main effects for the playing position for TD at peak 1-minute (p =.001) and PL at peak-3minute (p =.002). Team-level data showed a main effect for condition (score vs. concede) for 3-minute TD data and main effects for time (pre vs. post) for 1,3 and 5-minute epochs for PL data. The average and peak values were shown to differ across playing positions for all variables. Likewise, potentially indicative of tactical adjustments significant differences were observed at both a team and player level following scoring or conceding a goal. [ABSTRACT FROM AUTHOR]

This paper considers how player acceleration changes in soccer relative to age. A plot of average maximum acceleration versus age is produced. The construction of the plot is based on methods from functional data analysis and the availability of tracking data from the 2019 season of the Chinese Super League. For an individual player, we calculate his maximum acceleration for each single match of the 2019 season. Since the players' maximum accelerations are observed only on a single season instead of their entire careers, we treat them as incomplete functional data, called functional snippets. The average maximum acceleration, i.e., the mean function of the functional snippets rather than full curves is estimated by a local linear smoothing method. The most important observation is that the shape of the acceleration curve closely resembles curves of soccer performance versus age. This observation has implications for predicting future performance since acceleration is more easily and more accurately measured than performance. [ABSTRACT FROM AUTHOR]

This study determined the contributors to soccer technical skills in grassroots youth soccer players using a machine learning approach. One hundred and sixty-two boys aged 7 to 14 (mean ± SD = 10.5 ± 2.1) years, who were regularly engaged in grassroots soccer undertook assessments of anthropometry and maturity offset (the time from age at peak height velocity (APHV)), fundamental movement skills (FMS), perceived physical competence, and physical fitness and technical soccer skill using the University of Ghent dribbling test. Coaches rated player's overall soccer skills for their age. Statistical analysis was undertaken, using machine learning models to predict technical skills from the other variables. A stepwise recursive feature elimination with a 5-fold cross-validation method was used to eliminate the worst-performing features and both L1 and L2 regularisation were evaluated during the process. Five models (linear, ridge, lasso, random forest, and boosted trees) were then used in a heuristic approach using a small subset of suitable algorithms to achieve a reasonable level of accuracy within a reasonable time frame to make predictions and compare them to a test set to understand the predictive capabilities of the models. Results from the machine learning analysis indicated that the total FMS score (0 to 50) was the most important feature in predicting technical soccer skills followed by coach rating of child skills for their age, years of playing experience and APHV. Using a random forest, technical skills could be predicted with 99% accuracy in boys who play grassroots soccer, with FMS being the most important contributor. [ABSTRACT FROM AUTHOR]

The benefits of an external focus in motor learning have been well-established in adults, but findings in studies with children have been far more variable. Recent research also suggests that a holistic focus of attention may also enhance motor learning relative to an internal focus, but few studies have tested this strategy with children. Therefore, this study aimed to determine the effect of an internal (IF), external (EF), holistic focus (HF) and no focus control condition on the learning of a soccer shooting task in male children. Male participants (N = 60) between the ages of 9 and 11 completed 60 acquisition trials shooting at a low target at a distance of 7 m while focusing on an assigned cue. After 48 h, participants returned for a 10-trial retention test and a 10-trial transfer test shooting from a distance of 8 m. Results showed that the EF group was more accurate than control throughout acquisition (p =.027). In retention, all focus groups were more accurate than control (p 's <.001), and an EF trended toward being more accurate than in IF (p =.059). In transfer, all focus groups were more accurate than control (p 's <.001), and EF was more accurate than HF (p =.009). To our surprise, a clear benefit of an EF and HF relative to an IF was not observed. Future work should consider whether this may be due to the nature of the cues selected, or if there are other constraints that may influence when children do or do not benefit from an EF and HF. [ABSTRACT FROM AUTHOR]

This study assessed the between-day reliability of change of direction (COD) biomechanics and speed in youth soccer players using inertial measurement units (IMUs) and high-speed video. A soccer-specific COD test including a 180° pivot turn was performed in both directions by 15 elite female (age: 15.3 ± 0.6 years; height 162.6 ± 5.5 cm; body mass: 56.7 ± 7.1 kg) and 22 elite male (age: 15.4 ± 0.5 years; height 169 ± 5.9 cm; body mass: 58.5 ± 8.5 kg) youth soccer players in two consecutive days. The reliability of the variables was quantified by using intra-class correlation coefficient (ICC) analysis with limits of agreement (LoA) and Bland–Altman plots. Based on the results, neither peak resultant acceleration (PRA) nor peak angular velocity (PAV) during final foot contact was sufficiently reliable for 180° pivot turn biomechanics (poor reliability, < 0.5), but the reliability of players' running time to turn and total time was between acceptable to good (0.9>; > 0.7). However, when analyzing females and males separately, the PRA and angular velocity ICC's for females had poor to acceptable reliability, when turning left, and were statistically different from males (Z -score > 1.96). Acceptable to good reliability with reasonable (max 15% difference) LoA implies that speed measures in different phases of COD could reliably reproduce individual differences in 180° pivot turn COD speed. Sex-related differences in repeatability of acceleration and angular velocity call for more comprehensive research in the future. PAV and PRA would not be recommended for the purpose of analyzing individual repeatability of specific steps of COD movement. [ABSTRACT FROM AUTHOR]

The aims of this study were (i) to compare the sprint times between linear-sprint (LS) and curved-sprint (CS) tests of different radii, and (ii) to examine the relationships between sprint times in these tests in soccer players. Nineteen elite youth male soccer players (age, 18.6 ± 0.6 years) completed an LS test and three CS tests with different radii both from the left and the right side (11.15-m radius = CSwide, 9.15-m radius = CSmedium and 7.15-m radius = CSnarrow), each with a distance of 17 m. Differences in sprint times were examined using analysis of variance with Bonferroni-corrected pairwise comparisons and Cohen's d effect sizes (ES). Relationships between sprint times were determined by Pearson's product-moment correlations (r). Significantly lower sprint times were evident for LS compared to all three CS tests (p <.001, MD = 0.08–0.16 s, ES = 0.83–1.49), for CSwide compared to CSnarrow (p =.02, MD = 0.04 s, ES = 0.47) and for CSmedium compared to CSnarrow (p <.001, MD = 0.07 s, ES = 0.82). Very large correlations (p <.001, r = 0.75–0.80) were found between sprint times in LS and the three CS tests. Very large to nearly perfect correlations (p <.001, r = 0.79–0.91) were found within the three CS tests. Practitioners should be aware that sprint times are lower in LS compared to CS of different radii and that CS times are higher at narrower angles compared to wider angles. Given the high correlations within three CS tests, the application of only one CS (e.g., CSmedium) during a test battery may be sufficient if using different CS is not possible. Results of the correlation analysis also suggest that LS contributes to CS performance, however, to slightly different extents depending on the radius of the CS. Consequently, both LS and CS drills might be incorporated into sprint training practices of elite youth soccer players. [ABSTRACT FROM AUTHOR]

Objectives: To explore the differences in training and match load in English Premier League (EPL) 1st team and U23 players. Identifying differences in relative and absolute physical outputs in relation to Maximal Aerobic Speed (MAS) and Maximal Sprint Speed (MSS) and how this informs monitoring and training prescription. Methods: Two groups of full-time professional football players (1st team, n = 24 and U23 squad, n = 27) participated in this study. Training and match data were categorised into weekly blocks from Monday to Sunday. Each player's weekly total was then averaged to provide a squad average for each metric examined. Results: Match analysis identified significantly higher distance covered above 120% MAS and distance between 120% MAS and 85% MSS (p =.04, effect size [ES] = 0.64; p <.01, ES = 1.13) for the 1st team. Distance above 85% MSS was significantly higher for the U23's (p <.01, ES = 2.92). Training and match data during one-match weeks displayed significantly higher differences in all high-speed variables for 1st team players compared to U23 players (p ≤.05, ES = 0.82–1.78). Analysis of training and match data during a two-match week displayed no significant differences for all physical variables (p >.05). Conclusions: Practitioners should consider the utilisation of individual relative thresholds to identify differences between physical performance variables during training and matches for 1st team and U23 players. Utilising these comparisons to inform training design, could maximise players physical development and potential for successful transition. Importantly, these findings relate to only one EPL club and therefore practitioners should assess their own players' relative training and game outputs. [ABSTRACT FROM AUTHOR]

It is often suggested by fans, the media, and football commentators that English players are over-valued and receive higher salaries than those of comparable players from different countries. This study examines whether the suggestion can be empirically substantiated. Using a unique database covering all of the European elite leagues, we show that there is an English player value premium of around 40% and a wage premium of 25%. Exploring the reasons for this phenomenon in a regression setting, we find that the excess valuation and salary differential can be partly justified by several factors. First, and most importantly, there is a higher value attributed and wages paid to players in the English Premier League (EPL); second, that English players are more likely to play as strikers than in other positions in EPL clubs; third, that their performance in some positions is somewhat better than the average of players from other nations; fourth, that there are fewer of them in the top European leagues, leading to a shortage in supply. There is, however, evidence that the higher valuation of English attackers and the higher salaries of English attackers and of English midfielders evades explanation by any of these groups of variables. [ABSTRACT FROM AUTHOR]

Featured Application: Wind-tunnel tests of 3D-printed soccer balls with various surface features are used to create an equation that predicts the critical Reynolds number. Eight balls were manufactured with a 3D printer to resemble various types of 32-panel soccer balls. One ball was completely smooth, whereas the other seven possessed various dimple patterns on their surface panels. Seam width and seam depth were also varied. Wind-tunnel experiments were performed to extract aerodynamic coefficients, and also to determine the critical Reynolds number for each manufactured ball. A new surface roughness parameter is introduced, and a fitting formula is presented, which allows for the prediction of the critical Reynolds number if the new parameter is known. [ABSTRACT FROM AUTHOR]

Important decisions surrounding talent identification (TID), talent development (TD) and (de)selection within elite youth soccer are often grounded in the subjective opinions of coaches. These opinions often stem from coaches' observations of player performance, which have been shown to be susceptible to several biases. Additionally, previous research has failed to establish specific criteria on which such opinions are based, aside from a coach's own intuition and practical experience. This study aimed to create a communal language and aligned criteria for the specific purpose of evaluating players' performances. Semi-structured interviews were undertaken with nine experienced coaches (13.6 ± 10.8 years) from a professional UK soccer academy to identify coaches' perceptions of key position-specific soccer actions, performed during differing moments of the game, for evaluating individual match performance. Thematic analysis of the interview data permitted the extraction of several themes, posited to encompass the position-specific soccer actions highlighted by the coaches. Themes for outfield positions included attacking skills; defending skills; movements to receive, create or exploit space; receiving and releasing skills; support play; end product; press, recover to the ball, man or space; and tactical understanding. Goalkeeper themes included tactical understanding, positioning relative to the ball, danger, teammates and opponents, play forward, support play, choice of action and range of distribution. This study highlights an applied approach of creating a shared mental model for appraising player performances, which can facilitate discussion and knowledge exchange between coaches and practitioners, with the intention of improving decision-making around TID, TD and (de)selection decisions. [ABSTRACT FROM AUTHOR]

Soccer is described as a high-intensity, multidirectional sport requiring athletes to possess a high level of physical conditioning to compete at the elite level. Strength, linear sprint and change of direction (COD) abilities are key physical characteristics in soccer-specific performance, with research suggesting athletes who possess greater relative lower-body strength are superior in sprint and COD ability. The purpose of this study was to investigate the relationship between relative lower-body strength with linear sprint and COD ability among elite youth female soccer athletes in Western Australia. Forty-four (U13, n = 11; U14, n = 12; U15, n = 11; U19, n = 10) athletes completed an isometric mid-thigh pull (IMTP), 30 m sprint and 505 COD test. Results demonstrated a significant moderate correlation between relative IMTP (IMTPr) performance and 10 m (r = −0.315, p = 0.037) and 30 m (r = −0.0347, p = 0.021) sprint time, however, there was no significant correlation between IMTPr performance and COD deficit (r = −0.227, p = 0.168). This study suggests that relative lower-body strength is moderately related to greater sprint performance but not COD ability in elite youth female soccer athletes. Overall, relative lower-body strength appears to be advantageous to linear sprint performance in elite youth female soccer athletes, and therefore the inclusion of appropriate and targeted strength training in the physical preparation and long-term athlete development of this demographic may be recommended. [ABSTRACT FROM AUTHOR]

Purpose: The present study investigates to what extend de-contextualized practice is necessary to acquire technical skills in developmental soccer training. Typically, open play is considered beneficial for acquiring tactical skills, whereas specific drills are used to support the development of technical skills like passing and shooting. Therefore, a field-based study was designed to investigate the effectiveness of a Nonlinear Pedagogy (NP) approach in contrast to a classical Deliberate Practice approach to improve passing performance in young developmental soccer players. Method: Forty young male players (age 10 ± 1 years) were randomly assigned to three groups (PLAY, PRACTICE, and CONTROL). The PRACTICE group performed classical passing drills, whereas the PLAY group underwent a NP training regime. Passing skill was assessed before and after a 5-week training program using a standardized passing test according to the German Football Association. Additional retention testing was performed 5 weeks later. Results: The results indicated that, although the test design showed no specificity to the learning environment of the PLAY group, both groups improved passing skills after training, but the PLAY group displayed better results during retention testing (PRACTICE: p = 0.004, d = 0.48; PLAY: p = 0.001, d = 0.53) compared to the PRACTICE group. These findings are suggestive of general transfer learning in dynamic learning environments. Conclusion: The findings indicate that even when there is an emphasis on "technical skill" enhancement, more effective improvement in young development players may be observed through dynamic learning environments. Consequently, this study encourages coaches to design training regimes that afford players to train as they play. [ABSTRACT FROM AUTHOR]

The interest in tactical analysis in soccer has increased in the latest years, especially with the growing availability of player tracking data. With it, the defending team's compact organization, which is considered by practitioners to be an important factor in defense, was repeatedly examined. However, the connection between this defensive principle of play and the defending success remains unclear. Therefore, this study aims to investigate the relation of the principle of playing defensive compact organization to the success of the defense. Based on tracking and event data of 153 games of the German Bundesliga (season 2020/21), the compactness (surface area, spread of the team, and of defending subgroups) and the organization (distances between formation lines) of the defending team was compared between successful and unsuccessful defensive plays. There were almost no differences in the compactness of the whole team, and the organizational measures between successful and unsuccessful defensive plays. The defending subgroup of five defenders closest to the ball showed a higher compactness (smaller surface area and smaller spread) in successful defensive plays compared to unsuccessful ones (−0.08 ≤ d ≤ −0.16). Our results indicate that the compactness of players in areas close to the ball seems crucial for defensive success. However, the compact organization of the entire team does not seem important to regain the ball in defense. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to assess running load trends (total distance (TD), high-intensity distance (HID; > 5.5ms−1) and sprinting distance (SprD; > 7ms−1)) in the English Premier League (EPL) between the 2014/2015 and 2018/2019 seasons using a semi-automated optical tracking system. Methods: A total of 1634 games across 5 seasons (2014/2015–2018/2019) were analysed for team and positional TD, HID and SprD. All matches were tracked using TRACAB® Gen-4 HD motion cameras. Data were analysed to identify significant team and positional differences for each metric. Results: Small to moderate increases were seen in team running load for TD (p = 0.02; effect size (ES): 0.21), HID (p < 0.001; ES: 0.88) and SprD (p < 0.001; ES: 0.67) between 2014/2015 and 2018/2019. Positional analysis showed significant increases in TD for all except for defensive midfielders (DM), attacking midfielders (AM) and wide midfielders (WM) (p < 0.001–0.009; ES: 0.14–0.36); HID for all positions excluding goalkeepers (GK) (p < 0.001–0.007; ES: 0.2–0.54) and SprD for all positions except for GK, central midfielders (CM) and AM, (p < 0.001–0.020; ES: 0.19–0.39). Trivial to small differences were seen in season-to-season comparisons for TD (p < 0.001–0.023; ES: −0.16–0.52), HID (p < 0.001–0.033; ES: 0.10–0.38) and SprD (p < 0.001–0.025; ES: 0.13–0.27) for both team and positional differences. Conclusion: Small to moderate increases in team TD, HID and SprD occurred in the EPL between 2014/2015 and 2018/2019, with trivial to small changes in season-to-season variations. Actual changes in running load over time appear to be dependent on playing position. Running load trends should be updated regularly and practitioners should be aware of the variability within their team, and programme accordingly. [ABSTRACT FROM AUTHOR]

The purpose of this research was to prove the effectiveness of a soccer training program during a macrocycle (preparation and competition season) on the body composition and physical performances of young players. The research was conducted with a sample of 24 soccer players in two age groups: U15 (n=12) and U17 (n=12). The initial testing took place prior to the start of the preseason, whereas the final testing was performed after four months of training. The results prove that the soccer training program for the U15 age range causes important significant differences in the isokinetic force: peak torque flexion and peak torque extension. No significant changes were seen in body composition (body height/mass and muscle and fat mass) or vertical jump (Squat Jump - SJ, Counter-Movement Jump - CMJ, Maximal Counter-Movement Jump - CMJmax). The results also prove that the U17 soccer training program causes important statistical differences in muscle mass, fat mass, SJ, CMJ, CMJmax, and peak torque flexion, but there were no statistically significant changes in peak torque extension or body height/mass of the U17 soccer players. This research shows that the sensitive phase for relevant improvements in explosive force occurs after the age of 15 years, a period that is characterized by the dramatic development of muscle mass. [ABSTRACT FROM AUTHOR]

This study aimed to (a) detail the interlimb asymmetries during multi-directional jumping, change of direction and for ankle dorsiflexion range of motion and (b) determine how asymmetries and performance in multi-directional jumping and ankle dorsiflexion predict performance during change of direction tests. Twenty-two male semi-professional players completed a testing session which consisted of unilateral ankle dorsiflexion range of motion, vertical and horizontal unilateral and lateral countermovement jumps and left and right leg 90° (COD90L&R) and 180° (COD180L&R) change of direction tests. No significant differences between limbs were observed for any of the variables (P > 0.05), though vertical countermovement jump (11.1% ± 9.1%) and dorsiflexion range of motion (10.5% ± 10.3%) imbalances were greater than those during lateral (2.7% ± 2.2%) and horizontal (2.2% ± 1.9%) countermovement jumps, and 90° (3.6% ± 3.1%) and 180° change of direction (2.9% ± 3.6%). Subjects presented 3.4 ± 1.4 real asymmetries (i.e., one greater than the coefficient of variation) across the tests, with all subjects having at least one real asymmetry. Stepwise linear regression models explained a reasonable amount of variance in change of direction180R (70%), COD90L (57%), COD90R (39%), COD180L (23%) using the countermovement jump and dorsiflexion range of motion variables (P < 0.05). The current findings indicate that semi-professional soccer players have real bilateral asymmetries (particularly in countermovement jump and dorsiflexion range of motion), which practitioners should be cognizant of. Given the prediction value, change of direction performance can be predicted using performance and asymmetries during multi-directional jumping and ankle dorsiflexion. [ABSTRACT FROM AUTHOR]

Objectives: The purpose of the present study was to examine the direct and indirect effects of coach transformational leadership (TL) on the current lives of socio-economically disadvantaged individuals within a sport-based education programme. Design: Cross-sectional. Methods: 159 participants completed questionnaires on the perceptions of their lead coaches' TL, perceived basic need satisfaction (autonomy, competence, relatedness) in relation to programme attendance, and feelings of resilience and life-satisfaction in their current life. Results: PROCESS analysis revealed that all differentiated TL behaviours (but high-performance expectations) had a positive indirect effect on outcomes (resilience and life-satisfaction) via competence and a negative indirect effect on outcomes via relatedness. High-performance expectations demonstrated a direct effect on life satisfaction. Conclusion: The results demonstrate how distinct coach transformational behaviours impact differently on the lives of disadvantaged individuals within a sports-based education programme. The differentiated conceptualisation of TL revealed nuanced results, furthering our understanding of how each TL interacts with the three basic psychological needs. Finally, our results demonstrate the significance competence may hold in transferring the effect of different transformational behaviours onto the everyday lives of disadvantaged individuals. [ABSTRACT FROM AUTHOR]

Elite soccer players consistently report using several recovery methods after practices and games. However, it is unclear how their subsequent performance could be enhanced using broad protocols. The aim of this study was to compare the effectiveness of two different comprehensive recovery protocols in physiological, neuromuscular, and perceptual outcomes. Eighteen Mexican National Team players (19.56 ± 0.62 years) were recruited. Using a randomized parallel group design, players followed one of two recovery protocols: (a) carbohydrate and protein shake, foam roller, cold-water immersion, and tart cherry juice concentrate (n = 9) or (b) carbohydrate and protein shake, stretching, and intermittent cold-water immersion (n = 9) following the completion of an unofficial game and the day after. Muscular creatine kinase, countermovement jump, hamstring maximal voluntary contraction, perceived recovery, and muscle soreness were assessed before, immediately after, and 20-44-68 h post-game. Significant effects (set at ρ≤0.05) of time were present in both interventions. Muscular creatine kinase was normalized entirely at 68 h post-game, while neuromuscular and perceptual outcomes were homogenized at 44 h. No statistically significant effects between protocols were found. Still, the interaction effects showed changes only in the group using protocol (a) at post-game and 20 h after in neuromuscular and muscle soreness. There were large correlations between muscular creatine kinase and accelerations, decelerations, sprints, and high-speed running distances. In conclusion, the interventions are equally effective for improving physiological, neuromuscular, and perceptual outcomes. Thus, elite soccer players may benefit from different combinations of methods after practices or games to obtain positive effects on recovery after them. [ABSTRACT FROM AUTHOR]

The success of a soccer player is not entirely pre-destined by their physical ability, talent, and motivation. There are certain decisions along the way that greatly affect the arc of their career: which skills to develop, and which club to sign a contract with. In this paper, we identify the optimal strategic choices toward multiple potential aims a soccer player can have and we seek the knowledge of what made the greatest soccer players in terms of those decisions. Our two main data sources are Transfermarkt and Sofifa from which we collect data for the period between 2007 and 2021 with 29,231 players. We perform time series analysis on skill features of soccer players, and network analysis of the players' acquaintance graph, i.e., a graph that indicates whether two given players have ever been teammates before. Finally, we create key performance indicators to check the differences in certain features, i.e., individual player skills and connectivity attributes, between top-tier and the rest of the players, and use dynamic time warping for validation. The outcome of this work is a recommendation tool that helps players to find what needs to be improved in order to achieve their desired goals. The source code and the career advisor tool for soccer players that we have implemented are available online. [ABSTRACT FROM AUTHOR]

Soccer players need to make many decisions throughout a match in order to maximize their team's chances of winning. Unfortunately, these decisions are challenging to measure and evaluate due to the low-scoring, complex, and highly dynamic nature of soccer. This article proposes an end-to-end deep reinforcement learning framework that receives raw tracking data for each situation in a game, and yields optimal ball destination location on the full surface of the pitch. Using the proposed approach, soccer players and coaches are able to analyze the actual behavior in their historical games, obtain the optimal behavior and plan for future games, and evaluate the outcome of the optimal decisions prior to deployment in a match. Concisely, the results of our optimization model propose more short passes (Tiki-Taka playing style) in all phases of a ball possession, and higher propensity of low distance shots (i.e. shots in attack phase). Such a modification will let the typical teams to increase their likelihood of possession ending in a goal by 0.025. [ABSTRACT FROM AUTHOR]

In this pioneering work, we reflect on transfers in women's football. For this purpose, we collected all transfers from the two seasons with the most records in Portugal (the 2019/2020 and 2020/2021 seasons). The four dimensions associated with individual and prestige characteristics conducive to changing clubs, as well as 14 variables, were tested. For treating the problem of the endogeneity of some variables, we used a probit model with instrumental variables. The results obtained showed that high values of "goals per match" increase the probability of a player having an international transfer. Other determinants, such as the position of the transferring club or the player's field position, are also discussed in detail. [ABSTRACT FROM AUTHOR]

The aim of this paper was to describe the interactive effects of contextual and tactical dimensions on the creation of goal-scoring opportunities (GSO) in youth elite Spanish soccer, according to the type of possession. A total of 1730 team possessions from 24 qualifying matches of the official Spanish LaLiga Promises U12 and U13 soccer-7 tournaments were analyzed. For the analysis, team possessions were grouped into recoveries and restarts, according to the type of possession start. The study evaluated ten contextual and tactical dimensions by observational methodology. For recoveries, the multilevel binary regression models revealed significant effects of dimensions such as match status, initial field zone, initial penetration, type of attack, number of dribbles and number of passes on the creation of GSO. However, for restarts, only dimensions such as initial penetration, number of dribbles and possession width presented significant effects on the creation of GSO. In conclusion, the effects of different contextual and tactical dimensions in youth soccer teams seem to depend on whether the start of the team possession is a transition or a restart, regardless of the age category. These findings are useful for soccer coaches and analysts, which can help them understand the key dimensions in the design of training sessions in youth soccer teams. [ABSTRACT FROM AUTHOR]

This study quantified and compared the weekly locomotor activity and subjective load between elite and development loan youth soccer players registered to a primary club. Development loan players were loaned to a lower-league club and trained part-time with their loan club whilst being available for development fixtures and training with the primary club. Data were collected in 16 squad players and 4 development loan players at loan clubs across a 41 week competitive phase of the 2018/2019 season. Analysis was completed on total distance (m), PlayerLoadTM (au), low intensity running (<14.4 km·h−1, m), running (19.8–24.98 km·h−1, m), sprinting (>24.98 km·h−1, m), accelerations (>2 m·s−2 count) and decelerations (<−2 m·s−2, count). Point estimates for the development loan players consistently showed lower weekly values than squad players for all variables ranging from 5.2% (weekly sRPE) to 16.8% (weekly sprint distance covered). Differences, however, were not found to be statistically significant (p ≥ 0.07). Variance ranged from 23.6% (weekly distance) to 37.7% (weekly high-intensity accelerations). Although the goals of a development loan are likely to be multifactorial, this is the first study to quantify and compare locomotor activities and subjective loading of players within the development loan environment. [ABSTRACT FROM AUTHOR]

Differences exist between top-tier soccer leagues (e.g. anthropometry and match demands), which may influence strength and conditioning (S&C) practice. Thus, the aim of this study was to investigate whether current S&C practice in men's and women's (first team and academy) squads differed between global regions. A total of 170 participants, involved in the delivery of S&C support at their soccer club (based on South America (SA), the USA, the UK, or other European countries (EUR)), completed a survey examining their S&C methods. The survey comprised six sections: (i) academic qualifications and S&C coaching experience; and their preferred methods for (ii) physical testing; (iii) strength and power development; (iv) plyometric training; (v) speed development; and (vi) periodization. Coaches in EUR conducted fewer formal S&C sessions, placed less importance on free-weight resistance training (RT), and performed less speed and plyometric training compared to coaches in other global regions (all p < 0.05). While coaches working with UK squads devoted more time to physical development than those in EUR, they regarded bodyweight training as the most important RT modality in comparison to USA and SA, who prioritized free-weight RT. Finally, SA academy players are introduced to formal S&C later (∼14 years old) than those in the UK (∼12 years old, p = 0.002). However, it is reasonable to suggest that the S&C practice of coaches in the USA and SA align better with scientific guidelines for strength and power development in soccer, with emphasis on free-weight RT alongside regular sprint and plyometric training, compared to coaches in the UK and EUR. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine the effects of short sprint-distance training (SST) compared with long sprint-distance training (LST), matched for the total session training volume, on short-, medium- and long-distance sprint performance and agility in young soccer players. Eighteen U19 male players (age: 17.1 ± 0.7 years; height: 178.0 ± 6.3 cm, body mass: 69.4 ± 6.6 kg) were randomly assigned to SST (n = 9) or LST (n = 9) group. The intervention programs were performed 2 times a week over 6 weeks. Before and after training period, 5 m, 10 m, 20 m, 30 m and 40 m sprint, and agility were assessed. Within-group analysis showed significant improvements (p ≤ 0.001) in 5 m, 10 m, 20 m, 30 m and 40 m sprint from pretest to posttest in SST (9.2%, 6.6%, 5.3%, 2.9%, and 2.5%, respectively) and LST (10.5%, 8.5%, 6.5%, 5.1%, and 4.7%, respectively). Players in both SST and LST also showed significant enhancements in agility from pretest to posttest. In the between-groups analysis, there were no differences between the sprint training groups (SST vs. LST) in any variable (p > 0.05). In conclusion, the findings of this study indicate that both sprint training distances used seem to be effective to improve soccer-specific performance measures. However, due to the better percentage changes obtained by LST group in all fitness variables, this method could be considered as preferred method. [ABSTRACT FROM AUTHOR]

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This study explored academy football coaches' perceptions and experiences of managing individual differences in the maturity timing of male adolescent football players in an English Premier League academy. Using a longitudinal mixed method design, 98 under 12–16 players were assessed for maturity status, growth velocities, and match performance grade. Interviews with nine respective coaches were conducted in parallel. The qualitative and quantitative data were combined to generate a contextualised richer understanding and four archetypal case studies. Findings showed coaches perceive various advantages and disadvantages to players maturing either ahead or in the delay of their peers and had different expectations of performance based upon a players maturity status; biological maturity status and timing had large implications for selection and release decisions. This study highlights the challenges of developing, managing and selecting adolescent players in elite male youth football. Biological maturation confounds talent identification and development, and academy environments need to monitor maturity status and educate coaches and selectors on the complexities and intricacies of individual differences in maturity timing. [ABSTRACT FROM AUTHOR]

For male soccer players, the anthropometric profile and physical performance is already known but in women it is not well documented, the knowledge of these differences can qualify the training. Therefore, the aim of this study was two-fold: (i) to compare the anthropometric profile and physical fitness of Brazilian professional female and male soccer players; and (ii) analyze the relationships between anthropometric and physical fitness measures per sex. A cross-sectional study including 92 professional soccer players 44 women and 48 men was conducted. After one week of the end of the pre-season, the players from four different teams were assessed to anthropometric profile assessments and physical performance tests (e.g., jumping, linear sprint, change-of-direction and aerobic based test). Comparisons, correlation, and effect size analysis were performed between groups. Apart from the age and change-of-direction test, all other anthropometric and physical performance variables were significant different between women and men. Men were significantly faster than women in the 20 m linear sprint test (8.87%; p <.001; d = 2.382). The sum of skinfolds was correlated with some physical performance variables; however, body mass and body height were corrected with physical performance only for female soccer players. Thus, men performed better than women for most physical tests and presents differences in the anthropometric profile. Finally, coaches should consider that the anthropometric and performance profile are correlated differently between female and male soccer players. Thus, coaches should consider gender-specific parameters to create goals about the anthropometric and physical performance profile of players. [ABSTRACT FROM AUTHOR]

The current study aimed to analyse the effects of an in-season break period (2-week) on specific performance in amateur young female soccer players. Twelve female soccer players completed four assessment sessions, two before (BD-d1 and BD-d2) and two after (AD-d1 and AD-d2) a 2-week in-season break detraining period (both separated by 24 h). In each session, players completed a repeated sprint ability test (repeated sprint ability = 8 sprints of 30 m with 25 s of recovery), a countermovement jump test and locomotor performance in small-sided games (small-sided games = 3 sets of 5 min in a 5 vs. 5). Players exhibited a significant decrease in mean of repeated sprint ability (mean time of 8 sprints, p = 0.000, effect size = 2.04) and countermovement jump (p = 0.009, effect size = 1.39) performance between BD-d1 and AD-d1. The percentage of change between BD-d1 and BD-d2 from AD-d1 and AD-d2 shows significant differences (p = 0.05, effect size = 1.12) in best of repeated sprint ability (best time of 8 sprints) but not (p = 0.517, effect size = 0.31) in mean of repeated sprint ability. Significantly less high-intensity acceleration was performed in BD-d2 and AD-d2 from BD-d1 (p = 0.003, effect size = 3.21 and p = 0.002, effect size = 3.25, respectively). Only a 2-week in-season break inactivity was sufficient to decrease mean of repeated sprint ability and countermovement jump performance but not the best of repeated sprint ability. Therefore, it is necessary to apply specific training strategies to prevent decreases in performance in female soccer players in specific periods of the season. [ABSTRACT FROM AUTHOR]

The tactical formation is considered an important factor in soccer, however, changes in tactical formation during matches (in-game) and the distinction between offensive and defensive formations has rarely been considered in previous studies analyzing match performance. Therefore, objectives of this study were to investigate the following research questions: (i) How frequently do in-game formation changes occur? (ii) What contextual factors are associated with these changes? (iii) How often do defensive and offensive formations differ? The sample consisted of 81 matches (n = 162 single team cases) of the 2020/2021 German Bundesliga season. For each case, the starting formations (i.e. defensive and offensive) and in-game formation changes were recorded by observation of video data. For each in-game formation change, the contextual variables "point in time," "substitutions," and "goals" were recorded. In-game formation changes were found in 29.6% of the cases studied. Most in-game formation changes were discovered for the second half (95.2%), when the own team substituted at least one player (76.2%), and when the opposing team was leading the match (69.0%). In 25.3% of the investigated cases, the offensive and defensive formations of a team differed. Concluding, in-game formation changes are a relatively common phenomenon and, therefore, must be considered in the methodology of future research on tactical formation in soccer. The same applies to the distinction between offensive and defensive formation. Furthermore, coaches can use the findings to anticipate possible opposing team in-game formation changes earlier (e.g. in the second half, when the own team is leading and the opponent is substituting a player). [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the training effect of small-sided games played using large and small area per player on speed and endurance in college soccer players. Twenty male NCAA division 1 soccer players were randomly assigned to one of two experimental groups: small-sided games using a large area per player (n = 10), or small-sided games using a small area per player (n = 10). During the 4-week intervention, both groups performed three sets of 4–8 min of 5 versus 5 small-sided games using either a large (300 m2) or small (75 m2) area per player. Pre- and post-training, players completed linear sprint (20- and 40-m), repeated sprint, and aerobic endurance tests. Following the intervention, both groups exhibited improvements in 20-m, 40-m, and maximum sprinting speed (all p < 0.05, g = 0.04–0.29). No differences or interaction effects in repeat-sprint ability were found for either group (p > 0.05). A decline in maximal aerobic speed occurred in the small area per player group (p = 0.010, g = 0.60) whilst no change was reported for the large area per player group. Following the intervention, anaerobic speed reserve was lower for the large area per player group versus the small area per player group (p = 0.013; g = −0.23). No further between-group differences were reported at either time-point. These results suggest that small-sided games played with a small area per player may not be adequate to maintain aerobic fitness. [ABSTRACT FROM AUTHOR]

Purpose: To examine the recovery kinetics of exercise-induced muscle damage (EIMD), neuromuscular fatigue, and performance following small-sided games (SSGs) of different densities in soccer. Methods: Ten male players randomly completed 3 trials: a control trial (no SSGs), 4v4 SSGs (62.5 m2/player), and 8v8 SSGs (284.4 m2/player). External and internal load were monitored using GPS technology, heart-rate monitors, and rating of perceived exertion. Delayed-onset muscle soreness (DOMS), creatine kinase (CK), isokinetic strength, countermovement jump (CMJ), and sprint were determined at baseline, as well as at 24, 48, and 72 hours post-SSGs. Neuromuscular fatigue was assessed at baseline and at 1, 2, and 3 hours post-SSGs. Results: DOMS increased (P <.05) in 4v4 for 72 hours and in 8v8 for 24 hours with that of knee flexors being more pronounced than that of extensors. CK increased (P <.05) in 4v4 for 72 hours and in 8v8 for 24 hours. Neuromuscular fatigue increased (P <.05) in 4v4 for 2 hours and in 8v8 for 3 hours. Strength declined (P <.05) in 4v4 for 48 hours and in 8v8 for 72 hours. CMJ decreased (P <.05) in 4v4 for 24 hours and in 8v8 for 48 hours. Sprint decreased (P <.05) for 48 hours in 4v4 and for 72 hours in 8v8. Conclusions: SSGs are associated with a prolonged rise of EIMD and induce short-term neuromuscular fatigue and slow recovery kinetics of strength, jump, and sprinting performance. The time for complete recovery is longer for SSGs of lower density. [ABSTRACT FROM AUTHOR]

Soccer biomechanics is a field that applies principles of mechanics to improve performance and reduce the risk of injury for soccer players. The purpose of this research is to perform a mapping review of the existing knowledge in the current literature, identify leading researchers and institutions, and explore emerging research topics. After conducting a mini literature review, a bibliometric analysis was carried out using the VOSviewer software. The data imported into VOSviewer was obtained from the Scopus database and included 951 records. The analysis performed included: (a) performance analysis to calculate the number of records per year and the authors with the most citations; (b) science mapping analysis (co-authorship, co-citation, and bibliographic coupling); and (c) clustering analysis through the co-occurrence analysis of author keywords. Our findings highlight a significant growth in research publications on soccer biomechanics over the past few decades, with a notable increase in the number of articles published in high-impact journals. Additionally, the clustering analysis resulted in seven clusters, with each cluster providing valuable insights into different aspects of soccer biomechanics, which clearly reflects the multifaceted nature of the field.

Referees in sport are required to have specific perceptual-cognitive skills in order to make correct and consistent decisions. The current article explores those skills and describes the literature regarding perceptual-cognitive skills and decision making of referees in association football. First, we describe the importance of perceptual-cognitive skills in sports including pattern recall and recognition, postural cue usage, and the ability to understand situational probabilities and anticipate future events. Second, we discuss the state of the art on perceptual-cognitive skills in officiating including the concept of accurate versus adequate decision making, talent development in refereeing, training opportunities, embodied officiating, and the use of video technology. Finally, we discuss several directions for future research using representative decision-making task designs, considering contextual and psychological information, implementing training studies, and applying a multifactorial and longitudinal approach.

The purpose of this study was to examine the effects of short sprint-distance training (SST) compared with long sprint-distance training (LST), matched for the total session training volume, on short-, medium- and long-distance sprint performance and agility in young soccer players. Eighteen U19 male players (age: 17.1±0.7 years; height: 178.0±6.3 cm, body mass: 69.4±6.6 kg) were randomly assigned to SST ( n = 9) or LST ( n = 9) group. The intervention programs were performed 2 times a week over 6 weeks. Before and after training period, 5 m, 10 m, 20 m, 30 m and 40 m sprint, and agility were assessed. Within-group analysis showed significant improvements ( p ≤ 0.001) in 5 m, 10 m, 20 m, 30 m and 40 m sprint from pretest to posttest in SST (9.2%, 6.6%, 5.3%, 2.9%, and 2.5%, respectively) and LST (10.5%, 8.5%, 6.5%, 5.1%, and 4.7%, respectively). Players in both SST and LST also showed significant enhancements in agility from pretest to posttest. In the between-groups analysis, there were no differences between the sprint training groups (SST vs. LST) in any variable ( p > 0.05). In conclusion, the findings of this study indicate that both sprint training distances used seem to be effective to improve soccer-specific performance measures. However, due to the better percentage changes obtained by LST group in all fitness variables, this method could be considered as preferred method.

Abstract In the last decades, numerous post-mortem case series have documented chronic traumatic encephalopathy (CTE) in former contact-sport athletes, though reports of CTE pathology in former soccer players are scarce. This study presents a clinicopathological case of a former professional soccer player with young-onset dementia. The patient experienced early onset progressive cognitive decline and developed dementia in his mid-50 s, after playing soccer for 12 years at a professional level. While the clinical picture mimicked Alzheimer’s disease, amyloid PET imaging did not provide evidence of elevated beta-amyloid plaque density. After he died in his mid-60 s, brain autopsy showed severe phosphorylated tau (p-tau) abnormalities fulfilling the neuropathological criteria for high-stage CTE, as well as astrocytic and oligodendroglial tau pathology in terms of tufted astrocytes, thorn-shaped astrocytes, and coiled bodies. Additionally, there were TAR DNA-binding protein 43 (TDP-43) positive cytoplasmic inclusions in the frontal lobe and hippocampus, and Amyloid Precursor Protein (APP) positivity in the axons of the white matter. A systematic review of the literature revealed only 13 other soccer players with postmortem diagnosis of CTE. Our report illustrates the complex clinicopathological correlation of CTE and the need for disease-specific biomarkers.

Williams and Hodges (2005) stated five myths that soccer coaches held when organizing their athletes' practice. However, their arguments were based, majorly, in laboratory studies which limit their validity. Here, we performed a systematic review to verify the validity of their claims and map the current scenario of how coaches can manipulate factors of practice (augmented information, focus of attention, demonstration, and practice schedule) to support learning and performance in soccer. The results, in terms of each category or the myths presented, are, in most cases, not unanimous and much more must be performed to support, or criticize, coaches' practice. We provide an encompassing view that provides general ideas for practice and future research. [ABSTRACT FROM AUTHOR]

Heart rate variability (HRV) has become a popular method for monitoring readiness, recovery, and other training-derived parameters to optimize physical performance. This systematic review aimed to examine the impact of training interventions on HRV fluctuations in competitive soccer players. The EBSCO, Web of Sciences (WOS), and Cochrane databases were used for the search. After identifying 293 studies, 13 were included in a qualitative analysis and 6 in a quantitative analysis. Training had a small and nonsignificant effect on HRV in competitive soccer players (Effect Size (ES) = 0.143, Standard Error (SE) =.108, p =.186, 95% confidence interval (CI) [−0.69, 0.355]). Soccer-focused training resulted in higher HRV scores than combined training (Q(2) = 38.13, p =.05). Higher ES were found for frequency domain parameters (p =.047; d = 0.059), night assessment (p =.016; d = 0.453), and soccer-focused training (p =.006; d = 0.366). HRV was also found to have a greater impact on females (p =.027; d = 0.275) and/or professional soccer players (p =.007; d = 0.302). Soccer training had a minimal and nonsignificant effect on HRV. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the structure of relationships between measures of training load and assess whether these can be modified through non-linear transformations. Ratings of perceived exertion (RPE) and seven external load measures (total distance covered, PlayerLoad, low-intensity running distance, high-speed running distance, sprinting distance, accelerations, and decelerations) were collected from 20 academy soccer players (age = 17.4 ± 1.3 years, stature = 178.0 ± 8.1 cm, body-mass = 71.8 ± 7.2 kg), with 3220 recordings taken across a 47-week season. To control for the effects of session duration, sessions were categorised as short (≤60 min) or long (>60 min). All RPE and sessional RPE-training load (sRPE-TL; RPE multiplied by session duration) were analysed in their raw form and through raising to a series of exponentials. The underlying structure of the data was investigated using principal component analysis. Two components were retained for each analysis and varimax rotation was performed. The first rotated component (RC) was best represented as a measure of volume (RCvolume) with high loadings for RPE and sRPE-TL, whilst the second RC was best represented as a measure of intensity (RCintensity). Non-linear transformations had little effect on loading of modified measures for long sessions for sRPE-TL (RCvolume: 0.87–0.8; RCintensity: 0.27–0.13), and for RPE (RCvolume: 0.76–0.79; RCintensity: 0.17–0.10). For short sessions, the loading became more equal between intensity and volume for sRPE-TL (RCvolume: 0.88–0.41; RCintensity: 0.32–0.36) and more aligned to intensity (RCintensity: 0.52–0.61) compared with volume (RCvolume: 0.44–0.23) for RPE. The present study demonstrates that RPE and sRPE-TL predominantly reflect measures of training volume, however, they can be modified to better reflect intensity for training sessions <60 min in duration. [ABSTRACT FROM AUTHOR]

Background: The range values of different training and match intensity measures obtained to define benchmarks in female soccer players are needed. Usually, cohort studies analyse only one team with a relatively small sample size, which brings forth the need for a systematic review to generalise training and match intensity evidence. Objectives: This review aimed to identify and summarise studies that have examined external and internal training or match intensity monitoring to provide range values for the main measures in female soccer players. Methods: A systematic review of EBSCO, PubMed, Scielo, Scopus, SPORTDiscus and Web of Science databases was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Results: From the 2853 studies searched, 44 were analysed in which the following range intervals were found for training: rated perceived exertion (RPE, 1–7 AU), session-RPE (s-RPE, 51–721 AU), total distance (2347–6646 m) and distance >19.4 km·h−1 (9–543 m). For matches, the range values were s-RPE (240–893 AU), total distance (5480–10581 m), distance ≥14 km·h−1 (543–2520 m), ≥ 18 km·h−1 (96–1680 m), number of accelerations (49–240) and deceleration (21–85) and player load (848–1096 AU). Conclusions: This study provides range values of s-RPE, RPE, TRIMP, total distance and distance >19.4 km·h−1 regarding training; range intervals of s-RPE, heart rate average and maximum, total distance, distance ≥ 14 km·h−1, ≥ 18 km·h−1, ACC and DEC (> 2 ms−2) regarding matches for professional female players that can be used by coaches, practitioners or researchers to achieve similar training and competitive levels. [ABSTRACT FROM AUTHOR]

The number of investigations that specifically address the influence of formation on soccer performance has increased in recent years. Since there is no overview that summarizes these effects, this systematic review aims to synthesize the available literature on the effects of tactical formation on physical and technical match performance. According to the PRISMA 2020 guidelines, a systematic search was performed (Databases: PubMed and Web of Science). Studies were included, if they reported any physical (e.g., sprinting distance) or technical (e.g., number of passes) match performance parameters and compared at least two different formations. The study outcomes were synthesized descriptively. The effect of formation on physical performance was investigated in ten studies while three studies investigated the effect on technical performance (11 studies included). The studies revealed that formation has an effect on the physical and technical match performance of soccer players both in a team and at a positional level. On a team level, smaller differences were observed for formations that are similar in the number of players in each playing position (i.e., 4-5-1, 4-2-3-1). Furthermore, physical match performance was higher in formations with three defenders (e.g., 3-5-2) in comparison to formations with four defenders (e.g., 4-4-2). On a positional level, all positions were affected in a similar way by formation. Therefore, formation affects the physical and technical match performance of soccer players and if the playing position is also considered, the results become even more meaningful. The studies were very heterogeneous regarding their methodology (i.e., parameters, sample size). The findings can help coaches to design their training programs and to prepare the players for a specific positional role depending on the tactical formation. [ABSTRACT FROM AUTHOR]