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 Players' performance during worst-case scenarios in professional soccer matches: a systematic review
Reference: Biol Sport. 2021 Sep;39(3):695-713. doi: 10.5114/biolsport.2022.107022. Epub 2021 Aug 30.
Authors: Markel Rico-González, Rafael Oliveira, Luiz H Palucci Vieira, José Pino-Ortega, Filipe Manuel Clemente
Summary: Since the analysis of worst-case scenarios (WCS) has been increasing knowledge about match demands and possible impacts for the training process, it seems important to summarize the evidence to provide useful information for the soccer community. Thus, the purpose of this systematic review was to summarize the evidence about WCS in professional soccer. A systematic review of PubMed, SPORTDiscus, and FECYT (Web of Sciences, CCC, DIIDW, KJD, MEDLINE, RSCI, and SCIELO) was performed according to the guidelines for performing systematic reviews in sport science. From the 85 studies initially identified, 12 were fully reviewed, and their outcome measures were extracted and analyzed. There was an inverse relationship between the duration of WCS windows and running output during match play. Occurrences of WCS during soccer matches were also position-dependent across studies, at least, when analyzing performance with the total distance covered variable, although different outputs were identified between women and men players. Future research should consider analyzing the impact of contextual variables (match status, team formation, and match location) on peak match values and the weight of these moderators.
#2 Level of anxiety and results of psychomotor tests in young soccer players of different performance levels
Reference: Biol Sport. 2021 Sep;39(3):571-577. doi: 10.5114/biolsport.2022.106387. Epub 2021 Jul 23.
Authors: Dominika M Wilczyńska, Frank Abrahamsen, Agnieszka Popławska, Piotr Aschenbrenner, Marcin Dornowski
Summary: The aim of the current study is to determine how the level of state and trait anxiety differs between youth athletes of different performance levels and furthermore whether there are correlations between performance levels and psychomotor variables in the selected tasks. A sample of 97 boys, aged 11-12 years, practising soccer represented two groups: A - high performance level and B - lower performance level. Participants completed a state and trait anxiety inventory and performed selected psychomotor tests. The analyses demonstrated that the higher the levels of anxiety were, the shorter was the response time and more accurate were the responses in selected psychomotor tests. For the whole group, r = -0.224, p < 0.05, and for group B, r = -0.333, p < 0.05. Moreover, the findings showed a moderator effect of level (group A vs B) on reaction time, which was almost significant in state anxiety and significant in trait anxiety. For group B, trait anxiety was negatively related to reaction time (b = -0.002, SE = 0.001, t = -2.93, p = .004, 95% CI [-0.004, -0.001]). This means that the higher the trait anxiety was, the shorter was the reaction time in group B, but there was no significant effect in group A. The results of the study confirmed the negative correlation between the trait and state anxiety and reaction time. The higher the anxiety was, the shorter was the response time of child soccer players. Future research should determine whether athletes' performance levels do affect performance under stress and replicate the study with different samples such as girls and different sport disciplines.
#3 Training elite youth soccer players: area per player in small-sided games to replicate the match demands
Reference: Biol Sport. 2021 Sep;39(3):579-598. doi: 10.5114/biolsport.2022.106388. Epub 2021 Jul 28.
Authors: Andrea Riboli, Sigrid B H Olthof, Fabio Esposito, Giuseppe Coratella
Summary: The aim was to determine the area per player (ApP, m2 × player) in small- or large-sided games to replicate the official match demands in elite youth soccer players. Two hundred and twenty-eight players (U15 = 36, U16 = 48, U17 = 49, U18 = 37 and U19 = 58) were monitored during both training (12 183 individual samples) and matches (683 individual samples) across five seasons. Relative (m × min-1) total (TD), high-speed running (HSR), very high-speed running (VHSR), sprint and acceleration/deceleration (Acc/Dec) distance were collected. Between-category and between-position comparisons were performed. Area per player was moderately correlated (P < 0.05) with TD (r = 0.401), large (r = 0.621) with HSR, and very largely with VHSR (r = 0.744) and sprint (r = 0.723). An inverse small (r = -0.232; P = 0.039) correlation for Acc/Dec was found. The area per player to replicate the match demands was 158 ± 18, 182 ± 32, 197 ± 37, 212 ± 42 and 156 ± 25 m2 × player for TD, HSR, VHSR, sprint and Acc/Dec, respectively. Moderate to very large (ES: 0.79 to 4.66) differences in the area per player across metrics were observed, with sprint > VHSR > HSR > TD = Acc/Dec. Trivial to very large (ES: 0.01 to 2.67) between-category differences in area per player across the same metric were found, with U15 and U16 requiring a larger area per player than other age categories. These findings may help practitioners to recreate the desired external load outcomes with regards to positional match-play demands using specific area per player in small- or large-sided games in youth elite soccer players from U15 to U19.
#4 Effects of mental fatigue on technical performance in soccer players: A systematic review with a meta-analysis
Reference: Front Public Health. 2022 Jul 22;10:922630. doi: 10.3389/fpubh.2022.922630. eCollection 2022.
Authors: He Sun, Kim Geok Soh, Alireza Mohammadi, Xuanji Wang, Zuchang Bin, Zijian Zhao
Summary: Mental fatigue largely influences technical performance in soccer, including offensive and defensive skills. However, these effects on technical performance among the soccer players have not yet been aggregated to be assessed systematically. The purpose of the review was to evaluate the impact of mental fatigue on soccer players' overall technical skills. Drawing on Web of Science, PubMed, Scopus, and EBSCOhost (CENTRAL and SPORTDicus), an in-depth search was conducted. PICOS established the eligibility criteria to select the studies as follows: (i) population-healthy soccer players; (ii) intervention-involving any mental-fatigue-prompted protocol; (iii) comparison-control conditions (active or passive without inducing mental fatigue); (iv) outcomes-technical performance (offensive and defensive skill); and (v) study design-randomized controlled trials. A total of eight studies were qualified for inclusion in the systematic literature review. Overall, the results indicate that mental fatigue had significant effects on technical skills, including offensive and defensive skills. Specifically, there were significant effects on errors (ES = 0.977; p < 0.001), number of tackles (ES = -0.739; p = 0.005), and the percentage of successful tackles (ES = -0.628; p = 0.022), while there were no significant effects on the number of passes (ES = 0.240; p = 0.328), the percentage of accurate passing (ES = -0.008; p = 0.985), and the number of successful passes (ES = -0.322; p = 0.217). Overall, a significant effect of mental fatigue on the technical performance (e.g., tackles and errors) of soccer players was detected, while no significant effects on passing skills were detected. Future studies may consider investigating technical performance together with other important results (e.g., decision-making skills or internal load).
#5 Is the Rotatory Knee Stability Immediately Decreased Following a Competitive Soccer Match?
Reference: Front Bioeng Biotechnol. 2022 Jul 22;10:903131. doi: 10.3389/fbioe.2022.903131. eCollection 2022.
Authors: Alejandro Neira, Rony Silvestre, Aníbal Debandi, Daniel Darras, Iver Cristi-Sánchez, Ignacio Barra, Luis Peñailillo, Carlos De La Fuente
Summary: Fatigue induced by soccer playing increases physical efforts, which might alter the transverse knee stability, a known factor that promotes knee injuries, particularly anterior cruciate ligament injury. Thereby, primarily, we aimed to determine whether rotatory knee stability decreases immediately following a competitive soccer match in amateur players. Furthermore, we assessed the role of the preferred and non-preferred limbs to kick a ball in rotatory knee stability and the correlation between performance parameters and rotatory knee stability. We hypothesized that the knee stability decreases immediately after a competitive soccer match in amateur players. Eight healthy amateur soccer players (aged 27.2 ± 4.7 years and with body mass index of 23.8 ± 1.2 kg m-2) were included immediately before and after a competitive soccer match. The rotatory knee stability was assessed in the preferred and non-preferred limbs through the acceleration and jerk of the pivot shift maneuver and by the internal knee rotation of a pivoting landing task. Two-way repeated-measures ANOVA for factors time (before and after the soccer match) and limb (preferred and non-preferred) and multiple comparisons were performed using α = 5%. There was a statistical significance for the main factor time in the acceleration (5.04 vs. 6.90 ms-2, Δ = 1.86 ms-2, p = 0.020, η2 = 0.331) and jerk (18.46 vs. 32.10 ms-2, Δ = 13.64 ms-2, p = 0.004, η2 = 0.456) of the pivot shift maneuver. Rotatory stability decreases following a competitive soccer match in amateur soccer players under fatigue. Both the acceleration and jerk during the pivot shift maneuver is increased without significant internal knee rotation changes during the pivoting landing task.
#6 Pre-injury performance is most important for predicting the level of match participation after Achilles tendon ruptures in elite soccer players: a study using a machine learning classifier
Reference: Knee Surg Sports Traumatol Arthrosc. 2022 Aug 9;1-13. doi: 10.1007/s00167-022-07082-4.
Authors: Pedro Diniz, Mariana Abreu, Diogo Lacerda, António Martins, Hélder Pereira, Frederico Castelo Ferreira, Gino Mmj Kerkhoffs, Ana Fred
Summary: Achilles tendon ruptures (ATR) are career-threatening injuries in elite soccer players due to the decreased sports performance they commonly inflict. This study presents an exploratory data analysis of match participation before and after ATRs and an evaluation of the performance of a machine learning (ML) model based on pre-injury features to predict whether a player will return to a previous level of match participation. The website transfermarkt.com was mined, between January and March of 2021, for relevant entries regarding soccer players who suffered an ATR while playing in first or second leagues. The difference between average minutes played per match (MPM) 1 year before injury and between 1 and 2 years after the injury was used to identify patterns in match participation after injury. Clustering analysis was performed using k-means clustering. Predictions of post-injury match participation were made using the XGBoost classification algorithm. The performance of this model was evaluated using the area under the receiver operating characteristic curve (AUROC) and Brier score loss (BSL). Two hundred and nine players were included in the study. Data from 32,853 matches was analysed. Exploratory data analysis revealed that forwards, midfielders and defenders increased match participation during the first year after injury, with goalkeepers still improving at 2 years. Players were grouped into four clusters regarding the difference between MPMs 1 year before injury and between 1 and 2 years after the injury. These groups ranged between a severe decrease (n = 34; - 59 ± 13 MPM), moderate decrease (n = 75; - 25 ± 8 MPM), maintenance (n = 70; 0 ± 8 MPM), or increase (n = 30; 32 ± 13 MPM). Regarding the predictive model, the average AUROC after cross-validation was 0.81 ± 0.10, and the BSL was 0.12, with the most important features relating to pre-injury match participation. Most players take 1 year to reach peak match participation after an ATR. Good performance was attained using a ML classifier to predict the level of match participation following an ATR, with features related to pre-injury match participation displaying the highest importance.
#7 What are the significant turning demands of match play of an English Premier League soccer team?
Reference: J Sports Sci. 2022 Aug 9;1-10. doi: 10.1080/02640414.2022.2109355. Online ahead of print.
Authors: Thomas Dos'Santos, Ian Cowling, Matthew Challoner, Timothy Barry, Paul Caldbeck
Summary: This study aimed to compare the significant turning demands of English Premier League soccer match play relative to playing position using LiDAR technology. Turning data were collected from an English Premier League soccer team (2020-2021 season; 18 fixtures) using a Sportlight® LiDAR tracking system. Turns were tracked during match play, sub-categorised by entry speed (<3.0, 3.0-5.5, 5.5-7.0 and >7.0 m/s) and turning angle (Low: 20-59°; Medium: 60-119°; High: 120-180°). Turning metric frequencies were compared between playing positions (centre backs, full-backs, central midfielders, wide midfielders, and central forwards). On average, per match, central midfielders performed more total turns (~38 vs ~18-27), turns with entry speeds <3.0 (~15 vs ~7-10) and 3.0-5.5 m/s (~21 vs ~8-15) and low (~4 vs ~1-2), medium (~10 vs ~3-6) and high angled turns (~24 vs ~12-18) compared to all other playing positions (p ≤ 0.001, d = 0.96-2.74). Approximately, 90% of turns during matches were performed with entry speeds <5.5 m/s and ~63-70% were high angled turns. This study provides unique insights into the turning demands of English Premier League soccer matches , which can be used to inform position-specific physical preparation strategies, turning testing battery selection, agility drill construction, and rehabilitation and return to play standards.
#8 Effects of a Groin Pain Prevention Program in Male High School Soccer Players: A Cluster-Randomized Controlled Trial
Reference: Int J Sports Phys Ther. 2022 Aug 1;17(5):841-850. doi: 10.26603/001c.36631. eCollection 2022.
Authors: Kazuki Fujisaki, Kiyokazu Akasaka, Takahiro Otsudo, Hiroshi Hattori, Yuki Hasebe, Toby Hall
Summary: Groin pain is frequently reported by soccer players. A prevention program incorporating the Copenhagen adduction exercise (CAE) has been shown effective in decreasing adductor muscle injury in semi-professional soccer players. However, the effect of such programs on groin pain in high school soccer players is unknown. No reports have examined the effects of combining the CAE with other targeted exercises such as the Nordic hamstrings exercise (NHE). The purpose was to evaluate the preventative effects of exercise on groin pain in high school soccer players in three groups comprising NHE alone, combined NHE and CAE, and a control group. A cluster randomized controlled trial spanning 16 weeks was conducted on 202 high school soccer players from seven high schools in a Japanese under 18 Soccer League. Players were allocated to either group A (three schools, 66 players) receiving the CAE alone, or group B (two schools, 73 players) receiving the CAE and NHE, or control group C (two schools, 63 players) who performed their usual training. This study compared the number of injuries, injury rate, and severity of the injury of groin pain in these three groups. The number of players injured was less in group B (4 players) compared to C (18 players), and time-lost to soccer was less in groups A (6 players) and B (3 players) compared to group C (16 players). Injury rates were significantly lower in groups A and B, with the relative risk of injury compared to group C of 0.42 (95% CI 0.19% to 0.90%) in group A and 0.19 (95% CI 0.07 to 0.54) in group B. A 16-week program incorporating the CAE in training sessions in high school soccer players reduced the incidence of groin pain and which may be related to injury severity according to time -lost to soccer, however the combination of both the CAE and NHE may be more effective than the CAE alone.
#9 Towards More Sustainable Sports: Analyzing the Travel Behavior of Adolescent Soccer Players in Southern Norway
Reference: Int J Environ Res Public Health. 2022 Jul 30;19(15):9373. doi: 10.3390/ijerph19159373.
Authors: Aron Laxdal, Bjørn Tore Johansen, Elling Bere, Bård Erlend Solstad
Summary: Mitigating climate change is a global challenge demanding effort from all sectors, and sports are no exception. While transportation is one of the key issues regarding sustainable sports, the methods by which children and adolescents get to practice have not received much attention. The objectives of this study were, therefore, to present how adolescents in Southern Norway travel to soccer practice and assess how the mode of transportation is related to sex, socioeconomic status, age, ethnicity, and distance from home to practice. Cross-sectional data were collected from 558 adolescent soccer players (398 boys and 190 girls) representing 30 different clubs from settlements of varying rurality. While most of the participants lived within cycling distance from the field of practice, the majority opted for passive modes of transportation (55% passive vs. 45% active). A logistic regression analysis found that traveling distance and age were associated with active transportation habits, while sex, ethnicity, and socioeconomic status were not. Further research is needed to examine the main barriers to active travel for this already active population, as active transport represents an opportunity for sports to become more sustainable.
#10 Tell me how and where you play football and I'll tell you how much you have to run
Reference: Biol Sport. 2021 Sep;39(3):607-614. doi: 10.5114/biolsport.2022.106155. Epub 2021 Jul 28.
Authors: Julen Castellano, Ibai Errekagorri, Asier Los Arcos, David Casamichana, Andres Martín-Garcia, Filipe Manuel Clemente, Roberto López-Del Campo, Ricardo Resta, Ibon Echeazarra
Summary: The aim of this study was to describe the team accumulated physical response per minute considering only the effective playing time (EPT) attending to different contextual and strategic variables in the Spanish Football First Division (LaLiga Santander). A sample of 2,959 performances was included in the analysis, considering a 4-year period of analysis (from 2016-17 to 2019-20). The physical variables were: total distance covered with (DTminPOS) and without (DTminNOpos) possession of the ball, and distance covered at > 21 km·h-1 with possession (DT21minPOS) and without (DT21minNOpos). Two contextual variables, i.e. Place (Home/Away) and Score (Lost/Draw/Win), and two strategic variables, i.e. level of effective playing time (LevelETP) and level of possession of the ball (LevelPOS), were analysed. The teams ran more without possession of the ball than with possession; nevertheless, the teams that had less possession of the ball had higher values in the distance covered at > 21 km·h-1 with possession of the ball and vice versa. Furthermore, the strategic variables also had influence on the physical response (DT and DT21) of the teams,LevelETP and LevelPOS, although with interactive effects: longer playing time, less accumulated distance, and greater possession, greater accumulated distance in the defensive phase, both per min. The findings of this study may offer important practical implications to practitioners in order to assess physical performances of the players in matches, because it is crucial to integrate in the analysis the different contextual and strategic variables where the match has taken place to assess performances of the teams.
#11 Research on Video Target Detection and Tracking in Football Matches
Reference: Comput Intell Neurosci. 2022 Jul 31;2022:6951532. doi: 10.1155/2022/6951532. eCollection 2022.
Authors: Xiaoju Zou, Yuanling Huang, Nairun Zhou, Zuoming Fang
Summary: Computer vision is an interesting branch of artificial intelligence which is dedicated to how electronic devices can achieve the level of capabilities to perceive things just like ordinary human beings do. In order to solve the poor effect of video for the detection of target in football matches and the low accuracy of target tracking, this paper aims to make a deep exploration of the methods of video for the detection of target and tracking in football matches. The video moving for the detection of target method based on background model is used to extract the image in the background of the matching video which improves the light flow field. Secondly, the video differential image is acquired according to the difference of colors, the ghost target of the image in the video background model is scientifically determined, the ghost degree of the pixel points of the image is scientifically determined, and the flicker matrix of the target image is constructed. The number of pixels of the moving target is derived. A meanshift-based video target tracking algorithm is used in conjunction for the detection of target result to determine whether to track the target image until the overall video target tracking task is completed, move the central position of the target frame and background frame to the target position, select the best one to adapt to the target change, and determine whether to track the target image until the overall video target tracking task is completed. The simulation results suggest that the approach described in this study is capable of detecting and tracking moving objects, as well as improving target recognition and tracking accuracy.
#12 Exploring the Bedouin Syndrome in the Football Fan Culture: Addressing the Hooliganism Phenomena through Networks of Violent Behavior
Reference: Int J Environ Res Public Health. 2022 Aug 6;19(15):9711. doi: 10.3390/ijerph19159711.
Authors: Thyago Celso Cavalcante Nepomuceno, Victor Diogho Heuer de Carvalho, Lúcio Camara E Silva, Jadielson Alves de Moura, Ana Paula Cabral Seixas Costa
Summary: The Bedouin syndrome represents social interactions based on four premises: a friend of my friend is my friend, a friend of my enemy is my enemy, an enemy of my friend is my enemy, and an enemy of my enemy is my friend. These extensive associations exist in many social and economic relationships, such as market competition, neighborhood relations, political behavior, student gangs, organized crime, and the violent behavior of sports spectators (hooliganism) worldwide. This work tests the Bedouin syndrome hypothesis considering the violent behavior in the football fan culture. We construct relational networks of social affinities to represent the social interactions of organized fan bases (Torcidas organizadas) involved in hooligan violence in Pernambuco, Brazil. Contrary to prior expectations, the results evidence no statistical support for the Bedouin syndrome in 13 of the 15 analyzed clubs. There is weak statistical support in two interactions and strong statistical support in one interaction to state that a friend of my enemy is my friend (instead of an enemy). The only support for the Bedouin syndrome is circumstantial based on a prior assumption of an alliance. We propose a network development that can be more suitable to represent football fans' violent behavior. The results contribute to understanding the hooliganism social phenomenon in football-rooted cultures and their impact on public health, identifying potential determinants for organized violence by young spectators' and supporting police strategies by defining relevance scores for the most potential clashes and coalitions of gangs.
#13 How Do Male Football Players Meet Dietary Recommendations? A Systematic Literature Review
Reference: Int J Environ Res Public Health. 2022 Aug 3;19(15):9561. doi: 10.3390/ijerph19159561.
Authors: Karol Danielik, Anna Książek, Aleksandra Zagrodna, Małgorzata Słowińska-Lisowska
Summary: The aim of this review was to determine whether male football players meet dietary recommendations according to a UEFA expert group statement and to identify priority areas for dietetic intervention, including training periodization and field position. A database search of PubMed, Web of Science, EBSCO and Scopus was performed. To be included within the final review, articles were required to provide a dietary intake assessment of professional and semi-professional football players. A total of 17 studies met the full eligibility criteria. Several studies showed insufficient energy and carbohydrate intake compared to the recommendations. A majority of athletes consume adequate protein and fat intakes compared to the recommendations. In addition, several studies showed the insufficient intake of vitamins and minerals. This systematic review showed that football players do not meet the nutritional recommendations according to the UEFA expert group statement. Future research should be focused on how to apply nutritional recommendations specific for athletes in accordance with training periodization and positions on the field.
#14 "From everything to nothing in a split second": Elite youth players' experiences of release from professional football academies
Reference: Front Sports Act Living. 2022 Jul 22;4:941482. doi: 10.3389/fspor.2022.941482. eCollection 2022.
Authors: Thomas Ryan McGlinchey, Chris Saward, Laura Catherine Healy, Mustafa Sarkar
Summary: Previous research has assessed the affects release from football academies has on psychological distress and athletic identity of players. However, there has been no qualitative research exploring players' experiences of the release process. This study retrospectively explored players' lived experiences of being released from a professional football academy, having completed a scholarship (from ages 16-18). Four male football players (age 21.6 ± 1.5 years) who had experienced release from professional academies participated in in-depth semi-structured interviews. Data were analyzed using Interpretative Phenomenological Analysis. Four super-ordinate themes were interpreted from the data: Foreshadowing release-"left out in the cold", The process of release, Support during the process of release and New beginnings-"there's a bigger world than just playing football every day". Players reported that their contract meeting was a traumatic experience, and they experienced psychological difficulties in the longer-term following release. Factors that compounded the players' release were: a lack of aftercare being provided by the players' professional clubs for their wellbeing, and a disuse of social support, which hindered their transition out of full-time football. Context relevant recommendations are made to help improve the release process for elite youth football players.
#15 Analysis of Recovery Methods' Efficacy Applied up to 72 Hours Postmatch in Professional Football: A Systematic Review With Graded Recommendations
Reference: Int J Sports Physiol Perform. 2022 Aug 11;1-17. doi: 10.1123/ijspp.2022-0038. Online ahead of print.
Authors: Sérgio M Querido, Régis Radaelli, João Brito, João R Vaz, Sandro R Freitas
Summary: Sleep, nutrition, active recovery, cold-water immersion, and massage were recently reported as the most used postmatch recovery methods in professional football. However, the recommendations concerning the effect of these methods remain unclear. The purpose was t o systematically review the literature regarding the effectiveness of the most common recovery methods applied to male and female football players (or other team sports) 72 hours postmatches and to provide graded recommendations for their use. A systematic search of the literature was performed, and the level of evidence of randomized and nonrandomized studies was classified as 1 or 2, respectively, with additional ++, +, and - classification according to the quality of the study and risk of bias. Graded recommendations were provided regarding the effectiveness of recovery methods for physical, physiological, and perceptive variables. From the 3472 articles identified, 39 met the inclusion criteria for analysis. The studies' levels of evidence varied among methods (sleep: 2+ to 1++; nutrition: 2- to 1+; cold-water immersion: 2- to 1++; active recovery: 2- to 1+; and massage: 1- to 1+). Different graded recommendations were attributed, and none of them favored the effective use of recovery methods for physiological and physical parameters, whereas massage and cold-water immersion were recommended as beneficial for perceptive variables. Cold-water immersion and massage can be recommended to recover up to 72 hours postmatch at a perceptive level. However, there is a current need for high-quality research that identifies effective recovery strategies that enhance recovery at the physical and physiological levels.