As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases.
Following studies were retrieved for this week:
#1 Blood Biomarkers Variations across the Pre-Season and Interactions with Training Load: A Study in Professional Soccer Players
Reference: J Clin Med. 2021 Nov 27;10(23):5576. doi: 10.3390/jcm10235576.
Authors: Filipe Manuel Clemente, Francisco Tomás González-Fernández, Halil Ibrahim Ceylan, Rui Silva, Saeid Younesi, Yung-Sheng Chen, Georgian Badicu, Paweł Wolański, Eugenia Murawska-Ciałowicz
Summary: Pre-season training in soccer can induce changes in biological markers in the circulation. However, relationships between chosen hematological and biochemical blood parameters and training load have not been measured. Analyze the blood measures changes and their relationships with training loads changes after pre-season training. Twenty-five professional soccer players were assessed by training load measures (derived from rate of perceived exertion- known as RPE) during the pre-season period. Additionally, blood samples were collected for hematological and biochemical analyses. For hematological parameters, significant increases were found for platelets (PLT) (dif: 6.42; p = 0.006; d = -0.36), while significant decreases were found for absolute neutrophils count (ANC) (dif: -3.98; p = 0.006; d = 0.11), and absolute monocytes count (AMC) (dif: -16.98; p = 0.001; d = 0.78) after the pre-season period. For biochemical parameters, there were significant increases in creatinine (dif: 5.15; p = 0.001; d = -0.46), alkaline phosphatase (ALP) (dif: 12.55; p = 0.001; d = -0.84), C-reactive protein (CRP) (dif: 15.15; p = 0.001; d = -0.67), cortisol (dif: 2.85; p = 0.001; d = -0.28), and testosterone (dif: 5.38; p = 0.001; d = -0.52), whereas there were significant decreases in calcium (dif: -1.31; p = 0.007; d =0.49) and calcium corrected (dif: -2.18; p = 0.015; d = 0.82) after the pre-season period. Moreover, the Hooper Index (dif: 13.22; p = 0.01; d = 0.78), and all derived RPE measures increased after pre-season period. Moderate-to-very large positive and negative correlations (r range: 0.50-0.73) were found between the training load and hematological measures percentage of changes. Moderate-to-large positive and negative correlations (r range: 0.50-0.60) were found between training load and biochemical measures percentage of changes. The results indicated heavy physical loads during the pre-season, leading to a decrease in immune functions. Given the significant relationships between blood and training load measures, monitoring hematological and biochemical measures allow coaches to minimize injury risk, overreaching, and overtraining.
#2 In-Season Internal Load and Wellness Variations in Professional Women Soccer Players: Comparisons between Playing Positions and Status
Reference: Int J Environ Res Public Health. 2021 Dec 5;18(23):12817. doi: 10.3390/ijerph182312817.
Authors: Renato Fernandes, João Paulo Brito, Luiz H Palucci Vieira, Alexandre Duarte Martins, Filipe Manuel Clemente, Hadi Nobari, Victor Machado Reis, Rafael Oliveira
Summary: The internal intensity monitoring in soccer has been used more in recent years in men's football; however, in women's soccer, the existing literature is still scarce. The aims of this study were threefold: (a) to describe the weekly variations of training monotony, training strain and acute: chronic workload ratio through session Rated Perceived Exertion (s-RPE); (b) to describe weekly variations of Hooper Index [stress, fatigue, Delayed Onset Muscle Soreness (DOMS) and sleep]; and (c) to compare those variations between playing positions and player status. Nineteen players (24.1 ± 2.7 years) from a Portuguese BPI League professional team participated in this study. All variables were collected in a 10-week in-season period with three training sessions and one match per week during the 2019/20 season. Considering the overall team, the results showed that there were some associations between Hooper Index categories and s-RPE like stress or fatigue (0.693, p < 0.01), stress or DOMS (0.593, p < 0.01), stress or s-RPE (-0.516, p < 0.05) and fatigue or DOMS (0.688, p < 0.01). There were no differences between all parameters in playing positions or player status. In conclusion, the study revealed that higher levels of fatigue and DOMS occur concurrently with better nights of sleep. Moreover, any in-season variations concerning internal load and perceived wellness seems independent of position or status in outfield players. The data also showed that the higher the players' reported stress, the lower the observed s-RPE, thus possibly indicating a mutual interference of experienced stress levels on the assimilation of training intensity by elite women soccer players.
#3 The effect of bio-banding on academy soccer player passing networks: Implications of relative pitch size
Reference: PLoS One. 2021 Dec 16;16(12):e0260867. doi: 10.1371/journal.pone.0260867. eCollection 2021.
Authors: Christopher Towlson, Grant Abt, Steve Barrett, Sean Cumming, Frances Hunter, Ally Hamilton, Alex Lowthorpe, Bruno Goncalves, Martin Corsie, Paul Swinton
Summary: The primary aims of this study were to examine the effects of bio-banding players on passing networks created during 4v4 small-sided games (SSGs), while also examining the interaction of pitch size using passing network analysis compared to a coach-based scoring system of player performance. Using a repeated measures design, 32 players from two English Championship soccer clubs contested mixed maturity and bio-banded SSGs. Each week, a different pitch size was used: Week 1) small (36.1 m2 per player); week 2) medium (72.0 m2 per player); week 3) large (108.8 m2 per player); and week 4) expansive (144.50 m2 per player). All players contested 12 maturity (mis)matched and 12 mixed maturity SSGs. Technical-tactical outcome measures were collected automatically using a foot-mounted device containing an inertial measurement unit (IMU) and the Game Technical Scoring Chart (GTSC) was used to subjectively quantify the technical performance of players. Passing data collected from the IMUs were used to construct passing networks. Mixed effect models were used with statistical inferences made using generalized likelihood ratio tests, accompanied by Cohen's local f2 to quantify the effect magnitude of each independent variable (game type, pitch size and maturation). Consistent trends were identified with mean values for all passing network and coach-based scoring metrics indicating better performance and more effective collective behaviours for early compared with late maturation players. Network metrics established differences (f2 = 0.00 to 0.05) primarily for early maturation players indicating that they became more integral to passing and team dynamics when playing in a mixed-maturation team. However, coach-based scoring was unable to identify differences across bio-banding game types (f2 = 0.00 to 0.02). Pitch size had the largest effect on metrics captured at the team level (f2 = 0.24 to 0.27) with smaller pitch areas leading to increased technical actions. The results of this study suggest that the use of passing networks may provide additional insight into the effects of interventions such as bio-banding and that the number of early-maturing players should be considered when using mixed-maturity playing formats to help to minimize late-maturing players over-relying on their early-maturing counterparts during match-play.
#4 Characteristics of select and non-select U15 male soccer players
Reference: Biol Sport. 2021 Oct;38(4):535-544. doi: 10.5114/biolsport.2021.101126. Epub 2020 Dec 30.
Authors: Jan M Konarski, Magdalena Krzykała, Mateusz Skrzypczak, Monika Nowakowska, Manuel J Coelho-E-Silva, Sean P Cumming, Robert M Malina
Summary: Baseline characteristics of 31 healthy male U15 soccer players who were classified as select or non-select at the end of the season were compared. Players were 14.4 ± 0.54 years (13.6-15.3 years) at baseline; characteristics included body size, proportions and composition, estimated maturity status, several functional capacities, and coach classifications of potential in the sport. Decisions regarding selection or non-selection were made about two months after baseline. Select and non-select U15 soccer players differed significantly in estimated maturity status, body size, proportions and estimated muscle mass, functional tests related to speed, power and strength, and coach evaluation of potential, specifically tactical skills on offense and skills associated with creativity and decision making. When age and biological maturity status were statistically controlled, select and non-select players differed significantly only on the vertical jump, grip strength, and coach ratings of tactical skills on offense and of creativity and decision making. Results of stepwise discriminant analysis highlighted the importance of coach evaluation of tactical skills associated with offense, and of power and strength in distinguishing select from non-select players. The results highlight the advantages of advanced biological maturity status among adolescent male soccer players and also the importance of coach perceptions of talent. The latter implies a need for further study of the basis of coach perceptions, specifically how they are influenced by and perhaps interact with player characteristics at different ages, and how the perceptions influence playing time and player behaviors and interactions.
#5 The prevalence and practices of caffeine use as an ergogenic aid in English professional soccer
Reference: Biol Sport. 2021 Oct;38(4):525-534. doi: 10.5114/biolsport.2021.101125. Epub 2021 Jan 14.
Authors: Jason Tallis, Neil Clarke, Rhys Morris, Darren Richardson, Matthew Ellis, Emma Eyre, Michael Duncan, Mark Noon
Summary: The ergogenic properties of caffeine are well established, with evidence supporting beneficial effects for physical and technical elements of performance required for successful soccer match play. Despite this, recommended caffeine practices for professional soccer have not been established. Therefore, the present study aimed to evaluate the use and behaviours surrounding caffeine use in elite English soccer clubs. Representatives of 36 clubs from the top four tiers of English professional football (40%) completed an online survey that sought to determine if, when, how and why caffeine was prescribed to players as a means of improving sports performance. Of the clubs sampled, 97% indicated that caffeine is provided to players as a means of improving performance. Caffeine is most commonly administered prior to (> 94%) and during a game (> 48%), with frequency uninfluenced by time of matches. There was a broad range and lack of consistency in the timing, dose and mode of caffeine administration, but doses were typically low. Evidence from the present study indicate a translational gap between science and practice, highlighting a need for future work to better understand how caffeine consumption can be optimised with respect to the specific demands and constraints in professional soccer.
#6 Relationship between objective and subjective hydration measures on sprint performance among soccer players during actual matches in hot and humid environment
Reference: J Sports Med Phys Fitness. 2021 Dec 21. doi: 10.23736/S0022-4707.21.13413-9. Online ahead of print.
Authors: Man Y Lee, Teng K Khong, Norazmi Ramliy, Ashril Yusof
Summary: Studies that investigate the effect of hydration on soccer performance in the heat are mostly carried out in a laboratory-controlled environment or simulated setting. Generally, on site, hydration is measured subjectively. Hence, the relationships between objective and subjective hydration measures during actual soccer matches in natural hot and humid environment with performance remain unclear. Forty-two soccer players (age: 27.34 ± 3.62 years; BMI: 23.80 ± 2.70 kg / m2; temperature: 30.8 ± 1.92 º C; humidity: 82 ± 1.4 %) hydration status were assessed using urine specific gravity (USG) and bodyweight (BW) as the objective measures, meanwhile, thirst was measured subjectively using a thirst scale. For performance evaluation, 20 and 50 m sprint time were measured before and after match. The results showed a significant relationship between USG and sprint time (r = 1.00 (CI 0.98 - 0.99); p < 0.05), and as expected, USG at post-match was significantly higher than pre-match (p < 0.05) indicating dehydration. In line, changes (between post and pre-match) in BW also showed positive relationship with changes in sprint time (r = 0.99 (CI 0.98 - 0.99); p < 0.05). Not to our expectation, the self-reported thirst level was not found to be correlated with USG and sprint time. Objective measures better reflect hydration status and predict sprint performance compared to subjective measure when playing in hot and humid environment. Players need to monitor their hydration status to maintain their sprint performances.
#7 Perceptual-Motor and Perceptual-Cognitive Skill Acquisition in Soccer: A Systematic Review on the Influence of Practice Design and Coaching Behavior
Reference: Front Psychol. 2021 Dec 2;12:772201. doi: 10.3389/fpsyg.2021.772201. eCollection 2021.
Authors: Fynn Bergmann, Rob Gray, Svenja Wachsmuth, Oliver Höner
Summary: Facilitating players' skill acquisition is a major challenge within sport coaches' work which should be supported by evidence-based recommendations outlining the most effective practice and coaching methods. This systematic review aimed at accumulating empirical knowledge on the influence of practice design and coaching behavior on perceptual-motor and perceptual-cognitive skill acquisition in soccer. A systematic search was carried out according to the PRISMA guidelines across the databases SPORTDiscus, PsycInfo, MEDLINE, and Web of Science to identify soccer-specific intervention studies conducted in applied experimental settings (search date: 22nd November 2020). The systematic search yielded 8,295 distinct hits which underwent an independent screening process. Finally, 34 eligible articles, comprising of 35 individual studies, were identified and reviewed regarding their theoretical frameworks, methodological approaches and quality, as well as the interventions' effectiveness. These studies were classified into the following two groups: Eighteen studies investigated the theory-driven instructional approaches Differential Learning, Teaching Games for Understanding, and Non-linear Pedagogy. Another seventeen studies, most of them not grounded within a theoretical framework, examined specific aspects of practice task design or coaches' instructions. The Downs and Black checklist and the Template for Intervention Description and Replication were applied to assess the quality in reporting, risk of bias, and the quality of interventions' description. Based on these assessments, the included research was of moderate quality, however, with large differences across individual studies. The quantitative synthesis of results revealed empirical support for the effectiveness of coaching methodologies aiming at encouraging players' self-exploration within representative scenarios to promote technical and tactical skills. Nevertheless, "traditional" repetition-based approaches also achieved improvements with respect to players' technical outcomes, yet, their impact on match-play performance remains widely unexplored. In the light of the large methodological heterogeneity of the included studies (e.g., outcomes or control groups' practice activities), the presented results need to be interpreted by taking the respective intervention characteristics into account. Overall, the current evidence needs to be extended by theory-driven, high-quality studies within controlled experimental designs to allow more consolidated and evidence-based recommendations for coaches' work.
#8 Associations between 24-h heart rate variability and aerobic fitness in high-level female soccer players
Reference: Scand J Med Sci Sports. 2021 Dec 19. doi: 10.1111/sms.14116. Online ahead of print.
Authors: Júlio A Costa, João Brito, Fábio Y Nakamura, Hélder Dores, António Rebelo
Download link: https://onlinelibrary.wiley.com/doi/epdf/10.1111/sms.14116
Summary: The aim of this study was to investigate the changes in 24-h heart rate variability and aerobic fitness, and their associations, in female soccer players during the preseason period. Sixteen players were assessed (24-h HRV and Yo-Yo Intermittent Recovery Test, level 1 [YYIR1]) before and after 4 weeks of preseason. The relationship between R-R24h length and high-frequency oscillations (HF24h) was analyzed by a quadratic regression model (revealing or not saturation of vagal activity) assessed 48-h before (PRE-preseason) and 48-h after (POST-preseason) the preseason period. Additionally, the mean HF24h was calculated from the linear portion of the R-R interval versus the HF24h regression curve (HF index). The average of the corresponding R-R24h values was defined as the R-R index. In PRE-preseason, seven players had a saturated HF24h, while in POST-preseason, five new cases of saturated HF24h were observed. The mean R-R24h, HF24h, R-R index, and HF index lengths significantly increased after preseason (p < 0.001). Significant differences were found in YYIR1 PRE- compared with POST-preseason (930 ± 286 m [individual range: 400-1240 m] versus 1265 ± 252 m [640-1640 m], respectively; p < 0.001). Additionally, the relative changes in HF24h and HF index were largely correlated with improvements in the distance covered during the YYIR1 (r = 0.68 and r = 0.56; respectively). Enhanced vagal activity after 4-week preseason period of soccer training increased the occurrence of vagal saturation in high-level female soccer players. Additionally, the increases in HF24h and HF index were significantly correlated with aerobic fitness change.
#9 Impact of COVID-19 lockdown on match activity and physical performance in professional football referees
Reference: Biol Sport. 2021 Oct;38(4):761-765. doi: 10.5114/biolsport.2021.109451. Epub 2021 Oct 27.
Authors: Victor Moreno-Perez, María Luisa Martín-Sánchez, Juan Del Coso, Jose Luis Felipe, Javier Courel-Ibañez, Javier Sánchez-Sánchez
Summary: The aim was to investigate the effect of COVID-19 lockdown on match-play metrics in professional football referees during official matches of the Spanish professional leagues. Forty-two professional football referees from the First (n = 20) and Second Division (n = 22) were monitored during 564 official games using Global Positioning System (GPS) technology. Data of matches before lockdown were compared to matches after resumption of the competition. Compared to pre-lockdown, in the referees of the First Division there was a decrease in the total running distance and the distance covered at all speed thresholds > 6 km · h-1 after lockdown (P < .05). In the Second Division referees, the post-lockdown measurement only showed a decrease in the running distance at 21-24 km · h-1 (P < .05), with no changes in the other speed thresholds. The post-lockdown measurement showed an increased distance covered at < 6 km · h-1 and the number of accelerations for both First and Second Division referees (P < .05). Referees' match activity was reduced due to the COVID-19 lockdown, while the effect on running parameters was more pronounced in First Division referees.
#10 Professional football in times of COVID-19: did the home advantage effect disappear in European domestic leagues?
Reference: Biol Sport. 2021 Oct;38(4):693-701. doi: 10.5114/biolsport.2021.104920. Epub 2021 Mar 30.
Authors: Carlos H Almeida, Werlayne S Leite
Summary: This study aimed to examine how the home advantage (HA) and home teams' performances changed in European football leagues (German Bundesliga, Spanish La Liga, English Premier League, Portuguese Primeira Liga and Italian Serie A) with the measures imposed by legal authorities to deal with the COVID-19 pandemic (no audience, five substitutions and "cooling breaks"). The HA (Pollard's rescaled method) and home performance-related statistics of matches contested before (n = 491) and after (n = 491) the 2019-2020 season break were calculated and compared, for each league and for all five, using the paired t-test or the Wilcoxon signed-rank test. Overall, the HA did not significantly decrease in European leagues (from 16.4% to 11.6%; trivial effect size [ES]); however, a one-sample t-test revealed that the HA after the COVID-19 break was significantly greater than 0% (small ES). While the HA completely disappeared in the Bundesliga (large ES), its effects remained stable in La Liga (small ES), Premier League and Primeira Liga (trivial ES), and even increased in Serie A (medium ES) after the return. Home teams' performances in these leagues were influenced to different extents by the COVID-19 situation, especially by playing behind closed doors. Altogether, significant decreases were observed for total shots, tackles (medium ES), shots on target and pass success (small ES). Therefore, the role of crowd support seems to vary depending on the context characteristics in which football is played. Also, the augmented "information transfer" from coaches to players during COVID-19 matches might have masked the crowd effects on the HA.
#11 Organising football matches with spectators during the COVID-19 pandemic: What can we learn from the Amir Cup Football Final of Qatar 2020? A call for action
Reference: Biol Sport. 2021 Oct;38(4):677-681. doi: 10.5114/biolsport.2021.103568. Epub 2021 Feb 28.
Authors: Ismail Dergaa, Amit Varma, Montassar Tabben, Rubena Ali Malik, Sanaulla Sheik, Sakthikumar Vedasalam, Ahmed Khellil Abbassi, Jassim Almulla, Mokhtar Chaabane, Karim Chamari
Summary: The COVID-19 pandemic is a potential threat to professional sporting events when they eventually return to their usual calendar with spectators' capacity of football stadiums usually exceeding 40,000 seats for important events. Hence, a strategy for safe return to sporting events is needed in the COVID-19 pandemic to pave the way towards a new normalcy. We reviewed the guidelines and policies implemented in organising the Amir Cup Football Final of Qatar, which hosted about 20,000 fans. The authors evaluated the publicly available information on the official websites of the various organizations involved and highlight the importance and usefulness of the Covid-19 Rapid Antigen Assay-Kit as a tool for screening sports spectators as well as the importance of a rigorous spectator pathway, including their accurate traceability thanks to a specific mobile phone application. Despite the surging of COVID-19 all over the world, a big football event with around 20,000 spectators in the same stadium has been hosted under strongly controlled preventative measures. These preventative measures show that it is possible to organize a major football match held outdoors, with the presence of thousands of supporters. This article is a call for action for the organisers of such events where the supporters' health status is traceable to provide the scientific community with actual data of post-event infection rates. Therefore, it is suggested to consider using procedures like the ones described in the present article as a potential model in the process of organizing big sporting events with spectators in times of COVID-19.
#12 The Effects of Match Congestion on Physical Performance in Football Referees
Reference: Int J Sports Med. 2021 Dec 20. doi: 10.1055/a-1594-2739. Online ahead of print.
Authors: Víctor Moreno-Perez, Javier Courel-Ibáñez, Juan Del Coso, Javier Sánchez-Sánchez
Summary: We examined the changes in performance during congested (two matches within a 7-day interval) and non-congested (one match within≥7-day interval) fixtures in 17 elite football (soccer) referees during 181 official matches. External demands comprised 20 GPS-based metrics. Internal load was assessed by heart rate and rating of perceived exertion. Compared to non-congested fixtures, referees decreased their running distance at 21-24 km·h-1 (p=0.027, effect size [ES]=0.41) and > 24 km·h-1 (p=0.037, ES=0.28), the number of sprints (p=0.012, ES=0.29), and distance sprinting (p=0.022, ES=0.29) in congested matches. Most play metrics were lower in congested versus non-congested fixtures with low-to-moderate ES. During the 2nd half of non-congested fixtures, referees covered larger distances at low-speed running (p=0.025, ES=0.47). Match congestion due to officiating two matches less than a week apart caused a notable decrease in match running activity in professional football referees, especially at above 21 km·h-1. These data reiterate the need for specific conditioning and post-match recovery strategies in high-level referees to ensure optimal judgment performance favouring the quality of the competition. Governing bodies should take these outcomes into account when designating referees for a match.
#13 Bridge Over Troubled Water: Shared Understanding Bridges Individual and Collective Resources in Developing Team Resilience in Professional Football
Reference: Front Sports Act Living. 2021 Dec 1;3:705945. doi: 10.3389/fspor.2021.705945. eCollection 2021.
Authors: Ole Erik Grinde
Summary: This study explored how coaches facilitate coordinated activities through shared understanding in the processes of team resilience development. Constructs of shared information that underpin synchronised actions and behaviour in a team are investigated through individual experiences with a dialogic "we" perspective of appropriating and handling challenging situations. Interactional key elements underpin coordinated task actions within the team. Experiences of both players and coaches are investigated through semi-structured interviews and complementary texts such as an observation log and coach-meeting reports, originating as part of an action research process in the team environment. The interaction model is developed in the exploratory journey during the season with the team. The model suggests key strategic elements that help to bridge shared appropriation of information to strengthen role interactions between team members handling challenging situations. Coaching practise, which connects the interaction model to different team resources of coordinating activities in the development process, still needs to be explored from different contextual perspectives and environments, within the development of team resilience.
#14 Football is becoming more predictable; network analysis of 88 thousand matches in 11 major leagues
Reference: R Soc Open Sci. 2021 Dec 15;8(12):210617. doi: 10.1098/rsos.210617. eCollection 2021 Dec.
Authors: Victor Martins Maimone, Taha Yasseri
Summary: In recent years, excessive monetization of football and professionalism among the players have been argued to have affected the quality of the match in different ways. On the one hand, playing football has become a high-income profession and the players are highly motivated; on the other hand, stronger teams have higher incomes and therefore afford better players leading to an even stronger appearance in tournaments that can make the game more imbalanced and hence predictable. To quantify and document this observation, in this work, we take a minimalist network science approach to measure the predictability of football over 26 years in major European leagues. We show that over time, the games in major leagues have indeed become more predictable. We provide further support for this observation by showing that inequality between teams has increased and the home-field advantage has been vanishing ubiquitously. We do not include any direct analysis on the effects of monetization on football's predictability or therefore, lack of excitement; however, we propose several hypotheses which could be tested in future analyses.
#15 Factors Associated with Hip and Groin Pain in Elite Youth Football Players: A Cohort Study
Reference: Sports Med Open. 2021 Dec 19;7(1):97. doi: 10.1186/s40798-021-00392-w.
Authors: Jacob Schoffl, Katherine Dooley, Peter Miller, Jess Miller, Suzanne J Snodgrass
Summary: Despite hip and groin pain being commonly reported in elite youth football players, little evidence on risk factors exists. Risk factors in adult football players include reduced hip adductor strength and hip adductor/abductor strength ratios, and lower Copenhagen Hip and Groin Outcome Score (HAGOS) subscale scores. It is unknown if these factors are also predictive of pain development in youth football players. The aim was to identify whether preseason hip adductor and abductor strength and HAGOS subscale scores of male and female elite youth football players are associated with in-season or historical (lifetime) hip and groin pain. Preseason hip adductor and abductor strength testing and the HAGOS were undertaken by 105 elite male (n = 58) and female (n = 47) football players aged 11-15 years. Medical staff documented both players' self-reported historical and in-season hip and groin pain. Univariate and multivariate logistic regression models were undertaken with main outcome measures in-season hip and groin pain and historical hip and groin pain and independent variables of hip muscle strength, hip muscle torque and HAGOS subscale scores. Twenty-three players (21.9%) self-reported in-season hip and groin pain, while 19 players (18.1%) self-reported historical hip and groin pain. Pre-season hip adductor and abductor variables and HAGOS subscale scores failed to predict in-season hip and groin pain. However, a higher body mass index (odds ratio [OR] = 1.32; 95% CI 1.01, 1.73, p = .043) and being male (OR 5.71; 95% CI 1.65, 19.7) were associated with having in-season hip and groin pain (R2 = 0.211). There was also an association between historical hip and groin pain (R2 = 0.579) and both HAGOS subscale Quality of Life (odds ratio [OR] = 0.84; 95% CI 0.77, 0.91, p < .001) and mean abductor torque (OR = 11.85; 95% CI 1.52, 91.97; p = .018). Pre-season hip adductor and abductor strength and HAGOS subscale scores did not predict subsequent in-season hip and groin pain in elite youth football players. However, pre-season higher hip abductor strength and lower HAGOS scores were retrospectively associated with historical hip and groin pain.
#16 In-play forecasting in football using event and positional data
Reference: Sci Rep. 2021 Dec 17;11(1):24139. doi: 10.1038/s41598-021-03157-3.
Authors: Maximilian Klemp, Fabian Wunderlich, Daniel Memmert
Summary: Two highly relevant aspects of football, namely forecasting of results and performance analysis by means of performance indicators, are combined in the present study by analysing the value of in-play information in terms of event and positional data in forecasting the further course of football matches. Event and positional data from 50 matches, including more than 300 million datapoints were used to extract a total of 18 performance indicators. Moreover, goals from more than 30,000 additional matches have been analysed. Results suggest that surprisingly goals do not possess any relevant informative value on the further course of a match, if controlling for pre-game market expectation by means of betting odds. Performance indicators based on event and positional data have been shown to possess more informative value than goals, but still are not sufficient to reveal significant predictive value in-play. The present results are relevant to match analysts and bookmakers who should not overestimate the value of in-play information when explaining match performance or compiling in-play betting odds. Moreover, the framework presented in the present study has methodological implications for performance analysis in football, as it suggests that researchers should increasingly segment matches by scoreline and control carefully for general team strength.
#17 Analysis of more than 20,000 injuries in European professional football by using a citizen science-based approach: An opportunity for epidemiological research?
Reference: J Sci Med Sport. 2021 Nov 18;S1440-2440(21)00515-6. doi: 10.1016/j.jsams.2021.11.038.
Authors: Tim Hoenig, Pascal Edouard, Matthias Krause, Deeksha Malhan, Angela Relógio, Astrid Junge, Karsten Hollander
Summary: It has been claimed that analyses of large datasets from publicly accessible, open-collaborated ("citizen science-based") online databases may provide additional insight into the epidemiology of injuries in professional football. However, this approach comes with major limitations, raising critical questions about the current trend of utilizing citizen science-based data. Therefore, we aimed to determine if citizen science-based health data from a popular online database on professional football players can be used for epidemiological research, i.e. in providing results comparable to other data sources used in previously published studies.Transfermarkt.com (Transfermarkt; Hamburg; Germany) is a publicly accessible online database on various data of professional football players. All information provided in the section "injury history" of football players from the top five European leagues over a period of ten seasons (2009/10-2018/19) was analyzed. Frequency, characteristics, and incidence of injuries were reported according to seasons and countries, and results compared with three previously published databases (a scientific injury surveillance, a media-based study, and an insurance database). Overall, 21,598 injuries of 11,507 players were analyzed from the Transfermarkt.com database. Incidence was 0.63 injuries per player-season (95% confidence interval 0.62 to 0.64) but significant differences between subgroups (countries, years) were found. In comparison to other databases, citizen science-based data was associated with lower injury incidences and higher proportions of severe injuries. With few exceptions (e.g., severe injuries), the use of citizen science-based health data on professional football players cannot be recommended at present for epidemiological research.
#18 Effects of Three Different Combined Training Interventions on Jump, Change of Direction, Power Performance, and Inter-Limb Asymmetry in Male Youth Soccer Players
Reference: Sports (Basel). 2021 Nov 24;9(12):158. doi: 10.3390/sports9120158.
Authors: Alejandro Moreno-Azze, José Luis Arjol-Serrano, David Falcón-Miguel, Chris Bishop, Oliver Gonzalo-Skok
Summary: This study compared the effects of performing different unilateral combined training interventions on diverse vertical and horizontal jumping performance parameters, change of direction, concentric and eccentric mean power, and their associated inter-limb asymmetries in young soccer players. Forty-seven young male soccer players (age: 15.5 ± 0.9 years) were distributed into three groups. Two groups performed the same training volume with both legs, beginning with the weaker leg (Stronger Volume Weaker leg group (SVW), n = 14) or with the stronger leg (Stronger Volume Stronger leg group, (SVS), n = 15). The third group executed double the volume with the weaker leg and also commenced with such leg (Double Volume Weaker leg group (DVW), n = 16) during a 10-week period. Pre- and post-intervention tests included a single-leg hop, single-leg lateral hop, triple hop, bilateral and unilateral countermovement jumps, a change of direction speed test, concentric and eccentric mean power during the lateral squat test, and their corresponding asymmetries. Single-leg hop weaker leg, triple hop weaker leg, and bilateral countermovement jump improvements were achieved in the SVW (ES: 0.29 to 0.46) and DVW (ES: 0.55 to 0.73) groups. Between-groups analysis showed better results in single-leg hop in the SVW and DVW compared to group SVS. The DVW group achieved better improvements in countermovement jump in comparison to groups SVS and SVW. Groups that started with the weaker leg seemed to achieve a greater volume of significant changes than when starting with the stronger leg. Performing a double volume on the weaker limb does not guarantee further improved performance compared to other groups.
#19 Contextual Variation in External and Internal Workloads across the Competitive Season of a Collegiate Women's Soccer Team
Reference: Sports (Basel). 2021 Dec 8;9(12):165. doi: 10.3390/sports9120165.
Authors: Lauren E Rentz, William Guy Hornsby, Wesley J Gawel, Bobby G Rawls, Jad Ramadan, Scott M Galster
Summary: As sports technology has continued to develop, monitoring athlete workloads, performance, and recovery has demonstrated boundless benefits for athlete and team success. Specifically, technologies such as global positioning systems (GPS) and heart rate (HR) monitors have granted the opportunity to delve deeper into performance contributors, and how variations may exist based upon context. A team of NCAA Division I women's soccer athletes were monitored during games throughout one competitive season. Individual athlete, positional groups, and team external and internal workloads were explored for differences based upon game location, opponent ranking, game result, and the final score differential. Game location and opponent ranking were found to have no effect on team-wide absolute or relative external workloads, whereas game result and score differential did. Internal workloads across the team tended to only vary by game half, independent of game context; however, the HR of defenders was determined to be higher during losses as compared to wins (p = 0.0256). Notably, the games that resulted in losses also represented the games with the fewest number of substitutions. These findings suggest high value in monitoring performance and workloads that are characteristic of varying, often multifaceted, contexts. It is hoped that this information can lead to more informed approaches to vital game-time and coaching decisions.
#20 The Effectiveness of Virtual Reality on Anxiety and Performance in Female Soccer Players
Reference: Sports (Basel). 2021 Dec 13;9(12):167. doi: 10.3390/sports9120167.
Authors: Kaitlyn Harrison, Emily Potts, Adam C King, Robyn Braun-Trocchio
Summary: With the increased use of technology, relaxation interventions are finding their way into technology devices like virtual reality head-mounted displays (VR HMDs). However, there is a lack of evidence on the efficacy of VR relaxation interventions to reduce anxiety in athletes and how that is portrayed in their movement patterns. The purpose of the current study was to examine how a VR relaxation intervention affected perceived anxiety levels and penalty kick performance of female soccer players. Thirteen female soccer players took five penalty kicks in baseline, stress-induced, and VR relaxation conditions. Perceived levels of anxiety, self-confidence, mental effort, heart rate (HR), accelerometry of the lumbar spine and thigh, and performance in each condition was obtained. Results indicated that the VR intervention significantly reduced cognitive anxiety and somatic anxiety from baseline (p = 0.002; p = 0.001) and stress (p < 0.001; p < 0.001) with large effect sizes (Kendall's W = 0.72; 0.83). VR significantly increased self-confidence from baseline (p = 0.002) and stress (p = 0.001) with a large effect size (Kendall's W = 0.71). Additionally, all participants felt that VR helped them relax. Mental effort was significantly higher in the stress condition compared to that in baseline (p = 0.007) with moderate effect size (Kendall's W = 0.39). Peak acceleration and performance were not significantly influenced by stress or VR. This study serves as an initial step to evaluate VR relaxation interventions on performance in female soccer players.
#21 The impact of COVID-19 lockdown on professional soccer players' body composition and physical fitness
Reference: Biol Sport. 2021 Oct;38(4):733-740. doi: 10.5114/biolsport.2021.109452. Epub 2021 Oct 4.
Authors: Koulla Parpa, Marcos Michaelides
Summary: During the COVID-19 lockdown, professional soccer players ceased their regular team training sessions and were provided with exercise programs to follow independently. This investigation assessed the impact of a 7-week COVID-19 lockdown and home-based individual physical training on professional soccer players' body composition and physical fitness. The study consisted of nineteen division 1 elite soccer players (age 27.68 ± 5.99 years, height 178.47 ± 5.44 cm) and compared the anthropometric and physical fitness parameters obtained post-transition period to those obtained post-COVID-19 lockdown. The statistical analysis indicated that body fat percentage was significantly higher after the lockdown period [t(18) = -5.59, p < 0.01, d = 0.56]. Furthermore, VO2max [t(17) = -11.54, p < 0.01, d = 0.57] and running time [t(17) = 3.94, p < 0.01, d = 0.76] values were significantly higher after the COVID-19 lockdown than those obtained after the transition period. In addition, significantly higher level of performance was demonstrated on squat jump [t(18) = -4.10, p < 0.01, d = 0.30], countermovement jump [t(18) = -7.43, p < 0.01, d = 1.11] and sit and reach tests [t(19) = -5.33, p < 0.01, d = 0.32]. Concurrently, lower body strength was indicated to be significantly greater (p < 0.01) following the COVID-19 lockdown. The training protocol provided during the confinement, due to the COVID-19 outbreak, was effective in keeping physical fitness at a significantly higher level compared to the transition period. Coaches and trainers are encouraged to examine the effectiveness of this protocol, as it may help them develop effective periodization programs during the transition period. This protocol may aid in the development of effective periodization programs that require minimal equipment and can be followed in similar situations.
#22 Combining small-sided soccer games and running-based methods: A systematic review
Reference: Biol Sport. 2021 Oct;38(4):617-627. doi: 10.5114/biolsport.2021.102932. Epub 2021 Feb 11.
Authors: Filipe Manuel Clemente, Hugo Sarmento
Summary: Small-sided games (SSGs) are often used in soccer to produce acute physiological and physical responses, while a tactical/technical stimulus is also employed. However, due to some limitations of SSGs, researchers have been testing this method combined with running-based training methods. This systematic review was conducted to assess the effects of combined SSG and running-based methods on soccer players' acute responses and adaptations after training interventions. A systematic review of Web of Science, PubMed, Cochrane Library, Scopus, and SPORTDiscus databases was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The database search initially identified 782 titles. From those, five articles were deemed eligible for the systematic review. The five included studies presented data from training load, reporting inconsistent greater values in combined SSG and running-based methods when compared to SSG-only formats. Considering the adaptations, studies comparing combined SSG and running-based methods with SSG-only methods revealed inconsistent differences in terms of the effects on aerobic performance and sprinting. Combining SSG and running-based methods can increase the acute mechanical load and high-intense running stimuli in players when compared to interventions that use only SSGs. However, the adaptations promoted by both methods are similar, and the differences are unclear. The order of combination (SSG and running-based method) does not seem to impact players' adaptations; however, the frequency of sessions did have a meaningful impact.
#23 Maturity Has a Greater Association than Relative Age with Physical Performance in English Male Academy Soccer Players
Reference: Sports (Basel). 2021 Dec 20;9(12):171. doi: 10.3390/sports9120171.
Authors: John M Radnor, Jacob Staines, James Bevan, Sean P Cumming, Adam L Kelly, Rhodri S Lloyd, Jon L Oliver
Summary: This study aimed to: (1) examine differences in physical performance across birth-quartiles and maturity-status, and (2) determine the relationships among relative age, maturation and physical performance in young male soccer players. The sample included 199 males aged between 8.1 and 18.9 years, from two professional soccer academies in the English Football League. Data were collected for height, weight, self-reported biological parent heights, 30 m sprint time and countermovement jump (CMJ) height. Relative age was conveyed as a decimal, while maturity status was determined as the percentage of predicted adult height (PAH). There were no significant differences in any measure between birth quartiles, however early maturers outperformed on-time and later maturers in most performance measures. Pearson-product-moment correlations revealed that maturation was inversely associated with 30 m sprint time in U12 to U16 (r = -0.370-0.738; p < 0.05), but only positively associated with CMJ performance in U12 (r = 0.497; p < 0.05). In contrast, relative age was unrelated to sprint performance and only significantly associated with superior CMJ performance in U16. This study indicates that maturity has a greater association with sprint performance than relative age in English male academy soccer players. Practitioners should monitor and assess biological maturation in young soccer players to attempt to control for the influence on physical performance, and avoid biasing selection on absolute performance rather than identifying the most talented player.
#24 Training Management of the Elite Adolescent Soccer Player throughout Maturation
Reference: Sports (Basel). 2021 Dec 17;9(12):170. doi: 10.3390/sports9120170.
Authors: Alistair J McBurnie, Thomas Dos'Santos, David Johnson, Edward Leng
Summary: Professional soccer clubs invest significantly into the development of their academy prospects with the hopes of producing elite players. Talented youngsters in elite development systems are exposed to high amounts of sports-specific practise with the aims of developing the foundational skills underpinning the capabilities needed to excel in the game. Yet large disparities in maturation status, growth-related issues, and highly-specialised sport practise predisposes these elite youth soccer players to an increased injury risk. However, practitioners may scaffold a performance monitoring and injury surveillance framework over an academy to facilitate data-informed training decisions that may not only mitigate this inherent injury risk, but also enhance athletic performance. Constant communication between members of the multi-disciplinary team enables context to build around an individual's training status and risk profile, and ensures that a progressive, varied, and bespoke training programme is provided at all stages of development to maximise athletic potential.
#25 Short-term effects of on-field combined core strength and small-sided games training on physical performance in young soccer players
Reference: Biol Sport. 2021 Oct;38(4):609-616. doi: 10.5114/biolsport.2021.102865. Epub 2021 Feb 11.
Authors: Ersan Arslan, Yusuf Soylu, Filipe Manuel Clemente, Tahir Hazir, Ayse Kin Isler, Bulent Kilit
Summary: This study aimed to compare the effects of 6-weeks combined core strength and small-sided games training (SSGcore) vs. small-sided games (SSG) training on the physical performance of young soccer players. Thirty-eight amateur soccer players (age: 16.50 ± 0.51 years) were randomly assigned to either a SSGcore (n = 20) or a SSG group (n = 18). The SSGcore group performed upper and lower body core strength exercises combined with SSG including 2-, 3- and 4-a-sided soccer games third a week. The SSG group performed only the SSG periodization. Baseline and after the 6-week training period the Yo-Yo Intermittent Recovery Test level 1 (YYIRTL-1), 5-20-m sprint test, countermovement jump (CMJ), squat jump (SJ), triple-hop distance (THD), zigzag agility with ball (ZAWB) and without ball (ZAWOB), three corner run test (TCRT) and Y-balance test. The SSGcore group demonstrated meaningful improvements in 20 m sprint time (SSGcore: -9.1%, d = 1.42; SSG: -4.4%, d = 0.76), CMJ (SSGcore: 11.4%, d = 2.67; SSG: -7.7%, d = 1.43), SJ (SSGcore: 12.0%, d = 2.14; SSG: 5.7%, d = 1.28), THD (SSGcore: 5.0%, d = 1.39; SSG: 2.7%, d = 0.52) and TCRT (SSGcore: -3.7%, d = 0.69; SSG: -1.9%, d = 0.38). Furthermore, the SSGcore group demonstrated meaningfully higher improvement responses in both leg balance score (d = ranging from 2.11 to 2.75) compared with SSG group. These results suggest that the inclusion of core strength training to a SSG periodization is greatly effective to improve speed and strength-based conditioning in young soccer players.
#26 Impact of elite soccer coaching change on team performance according to coach- and club-related variables
Reference: Biol Sport. 2021 Oct;38(4):603-608. doi: 10.5114/biolsport.2021.101600. Epub 2021 Jan 14.
Authors: Miguel A Gómez, Carlos Lago-Peñas, María-Teresa Gómez, Sergio Jimenez, Anthony S Leicht
Summary: A coaching change is an extreme, but frequently occurring phenomenon in elite soccer with its impact on team success debatable. The aim of the current study was twofold: (i) to compare team's performance when coached by new and old coaches; and (ii) to investigate the impact of a coaching change on team's performance according to coach- and club-related factors. All in-season coaching changes from the 2010-11 to 2017-18 seasons within the Spanish, French, English, German and Italian professional leagues were examined. Team performance was assessed as points awarded from match outcome over 1-20 matches prior to and following the coaching change. Four independent variables (coach's experience, team's budget, whether the coach had been an elite former player or not, and whether the coach was a novice or not) were included into linear regression modelling. The main results showed that team's short-term performance was improved significantly with a change to a new coach with this impact declining in the longer term (> 10 matches). Specifically, the number of points (1.15-1.32 vs. 0.37-1.03, p < 0.05) and the moving average of points (1.19-1.31 vs. 0.37-1.04, p < 0.05) awarded per match were significantly greater after the coaching change. Further, the winning effect due to the new coach was independent of coach-related factors such as coaching experience or the new coach being a former elite player. A critical organisational decision to change coaches may provide an essential stimulus for future team success in elite soccer.
#27 Fitness improvements of young soccer players after high volume or small sided games interventions
Reference: Biol Sport. 2021 Oct;38(4):573-578. doi: 10.5114/biolsport.2021.100361. Epub 2020 Dec 31.
Authors: Karel Hůlka, Matej Strniště
Summary: The main goal was to determine anaerobic and aerobic improvement of young soccer players after six-week high volume (HVT) or small sided games (SSG) training intervention. One hundred and one highly trained youth soccer players (16.2 ± 1.3 years) were divided into SSG (n = 51) and HVT groups (n = 50) and according to age into an under sixteen subgroup (U16), under seventeen subgroup (U17), and under nineteen subgroup (U19). The performance was assessed by Yo-Yo intermittent test, Repeated sprint ability test (RSA), and K-test before and after both training interventions. For U16 the SSG group recorded significant improvements in the K-test (0.64 ± 0.56 s; p = .04) and RSA (0.15 ± 0.43 s; p = .01). For U19 the SSG group recorded the same improvements, in the K-test (0.43 ± 0.57 s; p = .007), RSA (0.21 ± 0.22 s; p = .048), and Yo-Yo test (127.25 ± 17.87; p = .049). HVT improved aerobic performance when the Yo-Yo test was significantly better after intervention at U17 (199.00 ± 111.83 m; p = .030), U19 (88.40 ± 66.38 m; p = .049). In total, the HVT group spent 621 min (56.45 ± 5.01 min) of aerobic training and the Small sided game group spent 291 min (26.45 ± 8.61 min) of small sided games focused on aerobic performance. This study showed that both SSG and HVT training interventions were effective for aerobic improvement for the U19 category, but not for younger players. SSG was identified to be more appropriate to fitness development of soccer players.
#28 Accumulative Weekly External and Internal Load Relative to Match Load in Elite Male Youth Soccer Players
Reference: Pediatr Exerc Sci. 2021 Dec 21;1-6. doi: 10.1123/pes.2021-0048. Online ahead of print.
Authors: Vicente de Dios-Álvarez, Pello Alkain, Julen Castellano, Ezequiel Rey
Summary: The aim of this study was 2-fold: (1) to assess and compare the external and internal load of elite young soccer players during competitive microcycles and (2) to describe the training/match ratios (TMr) in elite male youth soccer players. Twenty-one youth soccer players were monitored using a 10-Hz global positioning system. Total distance covered, running distance (RD), high-speed RD, sprint distance, number of accelerations and decelerations, player load, and rated perceived exertion were recorded during training sessions and matches. The TMr was calculated for each load measure. All variables were also normalized dividing the load per minute of activity. The RD, high-speed running, and sprint distance were higher 3 days before the match and 2 days before match compared with the rest of the training sessions. However, accelerations, decelerations, and player load were higher 4 days before match than other sessions. Besides this, the TMr of RD, high-speed running, and sprint distance were associated with lower values than the TMr of total distance covered, accelerations, decelerations, and player load. The match constituted the highest load during competitive microcycle. The present data support the idea that youth soccer coaches and practitioners must consider relative training load according to match demands to better manage and evaluate player periodization.
#29 Influence of contextual factors on physical demands and technical-tactical actions regarding playing position in professional soccer players
Reference: BMC Sports Sci Med Rehabil. 2021 Dec 16;13(1):157. doi: 10.1186/s13102-021-00386-x.
Authors: Adrián Díez, Demetrio Lozano, Jose Luis Arjol-Serrano, Elena Mainer-Pardos, Daniel Castillo, Marcelino Torrontegui-Duarte, Hadi Nobari, Diego Jaén-Carrillo, Miguel Lampre
Summary: The aim of this study was to analyse the physical demands and technical-tactical actions for each playing position according to game location and final outcome in professional soccer players. A convenience sample was obtained from twenty-one professional male soccer players, belonged to same soccer team of the Spanish Second Division. Players' physical demands were monitored during each match using a portable 18 Hz GPS unit and 600 Hz triaxial accelerometer. These analysed demands were total distance, moderate speed running distance (>14.4 km·h-1), high-speed running distance (>19.8. km·h-1), sprint distance (>25.0 km·h-1), number of accelerations between 2 and 4 m·s-2 and above 4 m·s-2, and number of decelerations between 2 and 4 m·s-2 and above 4 m·s-2. The data related to technical-tactical actions were obtained from WyScout®, a computerized multiple-camera tracking system based on the OPTA® track analysis tool. The obtained indicators were general, defensive and offensive. For all players, higher total distance (p = 0.045; effect size [ES] = 0.24, small effect) was covered and greater deceleration 2-4 m·ss-2 (p = 0.001; ES = 0.68, medium effect) was performed when the team plays at home and lose and for all players, playing at home and winning demanded higher defensive volume (p =0.014; ES = - 1.49, large effect) and nº interceptions (p =0.031; ES = - 1.40, large effect) in comparison to playing at home and losing. The physical demands and technical-tactical actions vary when contextual game factors (i.e., match location and final outcome) are considered. We can confirm that, although the training of physical demands does not influence the final result of the match, the training of technical tactical actions could help to achieve an optimal performance of the team to win matches.
#30 The Potentiating Response to Accentuated Eccentric Loading in Professional Football Players
Reference: Sports (Basel). 2021 Nov 26;9(12):160. doi: 10.3390/sports9120160.
Authors: Mark Steven Godwin, Tim Fearnett, Mark Ashton Newman
Summary: The purpose of this study was to assess the acute effect of Accentuated Eccentric Loading (AEL) on countermovement jump (CMJ) height, peak power output (PPO) and peak velocity in male professional footballers using loads of 20% or 40% of body mass (AEL20 or AEL40, respectively). Twenty-three male professional football players (age 24 ± 4.5 years, range 18-34 years; body mass 80.21 ± 8.4 kg; height 178.26 ± 7.62 cm) took part in a randomised, cross-over design to test the potentiating responses of two AEL conditions (AEL20 and AEL40) versus a body weight control group (CON). Mean loads for the two conditions were 15.84 ± 1.70 kg (AEL20) and 31.67 ± 3.40 kg (AEL40). There was no significant difference between the three conditions for jump height (p = 0.507, η2G = 0.022). There were significant differences in peak power between the groups (p = 0.001, η2G = 0.154). Post hoc analysis with Bonferroni adjustment showed significantly higher peak power for both AEL conditions compared to the control group, but no significant differences between AEL conditions (CON vs. AEL20, p = 0.029, 95% CI -1016.735, -41.815, Cohen's d = -0.56; CON vs. AEL40, p = 0.001, 95% CI -1244.995, -270.075, Cohen's d = -0.81; AEL20 vs. AEL40, p = 0.75, 95% CI -715.720, 259.201, Cohen's d = -0.24). There was no significant difference between the three conditions for peak velocity (p = 0.269, η2G = 0.046). AEL using either 20% or 40% of body mass may be used to increase peak power in the countermovement jump in well-trained professional football players.
#31 T-Pattern Detection and Analysis of Football Players' Tactical and Technical Defensive Behaviour Interactions: Insights for Training and Coaching Team Coordination
Reference: Front Psychol. 2021 Dec 6;12:798201. doi: 10.3389/fpsyg.2021.798201. eCollection 2021.
Authors: Tiago Fernandes, Oleguer Camerino, Marta Castañer
Summary: This article aims to study the coordination of the defenders' tactical and technical behaviour of successful teams to recover the ball according to contextual variables. A total of 15,369 (480.28 ± 112.37) events and 49 to 12,398 different patterns in 32 games of the 2014 FIFA World Cup's play-offs were detected and analysed. Results evidenced a T-pattern of the first defender pressuring the ball carrier and his teammates concentrating at the same zone to cover him or space, leading to ball recovery. Field zones, first defender tactical and technical behaviours, and ball carrier first touch constituted opportunities for defenders to coordinate themselves. Moreover, the third defender had a predominant role in his teammates' temporisation and covering zone behaviours. In the draw, first half, second-tier quality of opponent and play-offs excluding third place and final matches, the ball regularly shifted from upper to lower field zones in short periods, resulting in ball recovery or shot on goal conceded. Defenders performed behaviours farther from the ball carrier, and player-marking were most recurrent to an effective defence. This study's findings could help coaches give specific tips to players regarding interpersonal coordination in defence and set strategies to make tactical behaviour emerge globally.