Latest research in football - week 22 - 2022

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 Motion characteristics of under 15, under 17 and under 19 Italian youth women football (soccer) matches

Reference: J Sports Med Phys Fitness.  2022 Jun 10.  doi: 10.23736/S0022-4707.22.13923-X.

Authors: Enrico Mordillo, Matteo Zago

Summary: Despite the constant development of women's football, few studies to date addressed the physical requirements of youth female soccer players in regional (specific) contexts. This research characterized the activity profiles of élite Italian U15, U17 and U19 female games.  Sixty players (U15, n=18; U17, n=20; U19, n=22) from a high-level club in North-East Italy were involved. Players were equipped with a 10-Hz GPS device. Forty-six games were monitored (9 vs. 9 for U15, 11 vs. 11 for U17-U19) and the following dependent variables were extracted: total distance, equivalent distance, normalized distance (m/min) in six speed and metabolic power ranges. Total high-speed (>14.1 km/h) and total high-power (>18 W) distances were computed based on thresholds parametrized to the young female athlete. A multivariate General Linear Model was fit to analyze the effect of age category, match periods and their interaction. Some game parameters increased with age, especially from U15 to U17. Among them: total distance (5.5 km, 7.8 km, and 8.8 km for U15, U17, U19), distance at very-high (18-22 km/h) and maximum (>22 km/h) speed, distance at high power (18-31.5 W). Normalized distance was ~90 m/min and comparable among age groups. A reduction of very-high (31.5-49.5 W) and maximum power (>49.5 W) distance was observed in U15 matches, and of high-power distance in U17 and U19. These findings quantify the physical demands of Italian youth female match-play. These data support evidence-based training planning, set a reference for players approaching higher playing standards, and could back up informed redesign of playing formats.



#2 Efficacy of Electromyographic Biofeedback in Muscle Recovery after Meniscectomy in Soccer Players

Reference: Sensors (Basel). 2022 May 26;22(11):4024. doi: 10.3390/s22114024.

Authors: Verónica Morales-Sánchez, Coral Falcó, Antonio Hernández-Mendo, Rafael E Reigal

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Summary: Electromyographic biofeedback (EMG-BF) is a therapeutic technique that has been used successfully in the rehabilitation of injuries. Although it has been applied to athletes, its use in this field is not very widespread. The objective of this study is to analyze its effectiveness in the recovery of electromyographic activity of the quadriceps after meniscectomy, evaluated through isometric contraction of the vastus lateralis. The sample comprised ten professional footballers in the Spanish League (2nd Division A) who had previously suffered a meniscus injury in their knee and had undergone a meniscectomy. The intervention consisted of EMG-BF treatment lasting between 6 and 10 sessions. The electromyographic signal was recorded using a Thought Technology ProComp Infiniti 8-channel biofeedback unit with a sampling rate of 2048 samples/second. For each session, a within-subject ABA design of 6 or 10 trials per session was used, with three pre- and three post-measures, which determined the gain for each session. The results indicated (1) improvements in all cases, (2) EMG-BF was effective, (3) the working model was statistically significant with an explained variance of between 67% and 75%, and (4) the generalizability analysis showed that the results are reliable and generalizable. The results indicate that EMG-BF is effective in neuromuscular rehabilitation after this type of intervention.



#3 Investigating the Knuckleball Effect in Soccer Using a Smart Ball and Training Machine

Reference: Sensors (Basel). 2022 May 24;22(11):3984.  doi: 10.3390/s22113984.

Authors: David Eager, Karlos Ishac, Shilei Zhou, Imam Hossain

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Summary: The term knuckleball in sporting jargon is used to describe a ball that has been launched with minimal spin, resulting in a trajectory that is erratic and unpredictable. This phenomenon was first observed in baseball (where the term originated) and has since been observed in other sports. While knuckleball has long fascinated the scientific community, the bulk of research has primarily focused on knuckleball as it occurs in baseball. Following the changes in the design of the soccer ball after the 2006 World Cup, knuckleball and ball aerodynamics were exploited by soccer players. This research examined the properties of a knuckleball in the sport of soccer. We designed and evaluated a system that could reproduce the knuckleball effect on soccer balls based on previous theories and characteristics outlined in our literature review. Our system is comprised of the Adidas miCoach Smart Ball, a companion smart phone app for data collection, a ball-launching machine with programmable functions, and a video-based tracking system and Tracker motion analysis software. The results from the testing showed that our system was successfully able to produce knuckleball behaviour on the football in a highly consistent manner. This verified the dynamic models of knuckleball that we outline. While a small portion of the data showed some lateral deviations (zig-zag trajectory), this erratic and unpredictable trajectory was much smaller in magnitude when compared to examples seen in professional games. The sensor data from the miCoach app and trajectory data from the Tracker motion analysis software, showed that the knuckleballs were consistently reproduced in-line with theoretical dynamics.



#4 Consequences of the SARS-CoV-2 Infection on Anaerobic Performances in Young Elite Soccer Players

Reference: Int J Environ Res Public Health. 2022 May 25;19(11):6418. doi: 10.3390/ijerph19116418.

Authors: Marc Dauty, Jérôme Grondin, Pauline Daley, Bastien Louguet, Pierre Menu, Alban Fouasson-Chailloux

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Summary: The COVID-19 pandemic required local confinement measures reducing sport practice with possible consequences on the athletes' performances. Furthermore, anaerobic detraining was underestimated and poorly known in adolescents. This article aimed to assess the effects of SARS-CoV-2 infection and 1-month COVID-19 confinement on jump testing in young elite soccer players despite a 1-month multimodal training program followed by a 1-month soccer retraining period. Thirty-one elite soccer players aged 14 were included; 16 were infected by the SARS-CoV-2 and compared with 15 non-infected elite soccer players before and after 1 month of COVID-19 confinement, and after 1 month of a soccer retraining period. Squat jumps (SJ), countermovement jumps with (CMJs) and without arm swinging (CMJ) and multiple consecutive jumps (stiffness) were used to explore the anaerobic performances. Analysis of variance for repeated measures was used to compare the positive and negative SARS-CoV-2 groups, taking into account the confinement period (low training) and the retraining soccer period. The jump tests were not altered in the positive SARS-CoV-2 group compared to the negative SARS-CoV-2 group after confinement (SJ: 31.6 ± 5.6 vs. 32.7 ± 3.7; CMJ: 34.1 ± 6.9 vs. 34.2 ± 2.6; CMJs: 38.6 ± 6.8 vs. 40.3 ± 3.9; stiffness: 28.5 ± 4.3 vs. 29.1 ± 3.7) and at 1 month of this period (SJ: 33.8 ± 5.5 vs. 36.2 ± 4.6; CMJ: 34.7 ± 5.5 vs. 36.4 ± 3.5; CMJs: 40.4 ± 6.7 vs. 42.7 ± 5.5; stiffness: 32.6 ± 4.7 vs. 34.0 ± 4.3). The SARS-CoV-2 infection had no consequence on anaerobic performances assessed by jump tests in adolescent soccer players. The adolescents' growth could explain the absence of alteration of jump performances during the COVID-19 confinement. These results can be useful to manage the recovery of the anaerobic fitness after SARS-CoV-2 infection occurring in adolescent athletes.



#5 Visual tracking assessment in a soccer-specific virtual environment: A web-based study

Reference: PLoS One. 2022 Jun 9;17(6):e0269643. doi: 10.1371/journal.pone.0269643. eCollection 2022.

Authors: Alexandre Vu, Anthony Sorel, Charles Faure, Antoine Aurousseau, Benoit Bideau, Richard Kulpa

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Summary: The ability to track teammates and opponents is an essential quality to achieve a high level of performance in soccer. The visual tracking ability is usually assessed in the laboratory with non-sport specific scenarios, leading in two major concerns. First, the methods used probably only partially reflects the actual ability to track players on the field. Second, it is unclear whether the situational features manipulated to stimulate visual tracking ability match those that make it difficult to track real players. In this study, participants had to track multiple players on a virtual soccer field. The virtual players moved according to either real or pseudo-random trajectories. The experiment was conducted online using a web application. Regarding the first concern, the visual tracking performance of players in soccer, other team sports, and non-team sports was compared to see if differences between groups varied with the use of soccer-specific or pseudo-random movements. Contrary to our assumption, the ANOVA did not reveal a greater tracking performance difference between soccer players and the two other groups when facing stimuli featuring movements from actual soccer games compared to stimuli featuring pseudo-random ones. Directing virtual players with real-world trajectories did not appear to be sufficient to allow soccer players to use soccer-specific knowledge in their visual tracking activity. Regarding the second concern, an original exploratory analysis based on Hierarchical Clustering on Principal Components was conducted to compare the situational features associated with hard-to-track virtual players in soccer-specific or pseudo-random movements. It revealed differences in the situational feature sets associated with hard-to-track players based on movement type. Essentially with soccer-specific movements, how the virtual players were distributed in space appeared to have a significant influence on visual tracking performance. These results highlight the need to consider real-world scenarios to understand what makes tracking multiple players difficult.



#6 Multiple Players Tracking in Virtual Reality: Influence of Soccer Specific Trajectories and Relationship With Gaze Activity

Reference: Front Psychol. 2022 May 20;13:901438. doi: 10.3389/fpsyg.2022.901438. eCollection 2022.

Authors: Alexandre Vu, Anthony Sorel, Annabelle Limballe, Benoit Bideau, Richard Kulpa

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Summary: The perceptual-cognitive ability to track multiple moving objects and its contribution to team sports performance has traditionally been studied in the laboratory under non-sports specific conditions. It is thus questionable whether the measured visual tracking performance and the underlying gaze activity reflected the actual ability of team sports players to track teammates and opponents on a real field. Using a Virtual Reality-based visual tracking task, the ability of participants to track multiple moving virtual players as they would do on a soccer field was observed to pursue two objectives. (i) See the influence of different scenario types (soccer-specific trajectories versus pseudo-random trajectories) on the visual tracking performance of soccer (n = 15) compared to non-soccer players (n = 16). (ii) Observe the influence of spatial features of the simulated situations on gaze activity between soccer players and non-soccer players. (i) The linear mixed model regression revealed a significant main effect of the group but no interaction effect between group and the type of trajectories, suggesting that the visual tracking ability of soccer players did not benefit from their specific knowledge when they faced scenarios with real game trajectories. (ii) Virtual players' spatial dispersion and crowding affected the participants' gaze activity and their visual tracking performance. Furthermore, the gaze activity of soccer players differed in some aspects from the gaze activity of non-soccer players. Assumptions are formulated as to the implication of these results in the difference in visual tracking performance between soccer players and non-soccer players. Overall, using soccer-specific trajectories might not be enough to replicate the representativeness of the field conditions in the study of visual tracking performance. Multitasking constraints should be considered along with motor-cognitive dual-tasks in future research to develop the representativeness of visual exploration conditions.



#7 The incidence and severity of COVID-19 in adult professional soccer players in Russia

Reference: PLoS One. 2022 Jun 6;17(6):e0265019. doi: 10.1371/journal.pone.0265019. eCollection 2022.

Authors: Eduard Bezuglov, Vladimir Khaitin, Artemii Lazarev, Evgeniy Achkasov, Larisa Romanova, Mikhail Butovskiy, Vladimir Khokhlov, Maxim Tsyplenko, Alexander Linskiy, Petr Chetverikov, Magomedtagir Sugaipov, Arseniy Petrov, Oleg Talibov, Zbigniew Waśkiewicz

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Summary: There are little data on the incidence, and clinical course of COVID-19 among professional soccer players, and the studies examining putative complications of COVID-19 infections are probabilistic. On February 28, the WHO raised the COVID-19 threat assessment to its highest level. The COVID-19 outbreak became a significant challenge for world health. Around 30 million people got infected with COVID-19 since the beginning of this year. More than 900.000 decease. Thus, examining the incidence of COVID-19 and various aspects of its clinical course in a group of adult professional soccer players would be of great practical interest. The incidence, clinical practice, and severity of COVID-19 infection, as well as the duration of treatment and return to play was studied based on a survey of team physicians and medical records assessment in the group of adult professional soccer players representing the clubs of the Russian Premier-League (RPL) during the period of championship resumption from 01.04.2020 until 20.09.2020. COVID-19 infection was detected in 103 soccer players during COVID-19 screening. This number comprises 14.5% of all soccer players on the rosters of RPL soccer teams and is subjected to regular COVID-19 testing. The asymptomatic course was observed in 43.7% of cases (n = 45). These players were isolated, and their clinical condition was monitored closely. In 56.3% of patients (n = 58), fatigue, headache, fever, and anosmia were the most common symptoms. COVID-19 infection was commonly diagnosed among adult professional soccer players in Russia. However, most cases had a mild course and did not impair return to regular exercise. Only two players were hospitalized with lung lesions and returned to regular sports.



#8 Players at home: Physical activity and quality of life in 12-17 years-old football (soccer) players during the Covid-19 lockdown

Reference: Int J Sports Sci Coach. 2022 Jun;17(3):626-636. doi: 10.1177/17479541211041703.

Authors: Matteo Zago, Nicola Lovecchio, Manuela Galli

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Summary: Aggressive preventive actions were required to face the Covid-19 outbreak. However, from March 2020 on, many healthy youth football players have seen their sporting activities disrupted by the restrictions on outdoor exercise.This study describes physical activity and quality of life during April 2020 lockdown of young people participating in organized football. 1163 young football players aged 12-17 years (185 girls) completed a web-based questionnaire including the Youth Physical Activity and the Youth Quality of Life-Short Form Questionnaires; information on lifestyle and football-specific activity were also collected. Differences according to sex, urban/rural context and élite/non-élite club level were tested using a 2 ×× 2 ×× 2 MANOVA (age considered as a covariate). We found that: (i) on average, exposure to football accounted for 3.2 hours/week, was higher in élite clubs and changed in nature, being mainly performed individually; 19% of participants practiced football <1 hour/week; (ii) only 56% of the participants reported 7 or more hours/week of moderate-to-vigorous physical activity, which decreased with age and changed according to the geographical context; (iii) perceived quality of life was lower in youth playing for non-elite clubs and in older girls; (iv) coaches, rather that official initiatives, were the primary source of football exercises practiced at home. A status of limited physical activity emerged; this might lead to deconditioning and susceptibility to injuries when football could restart. Governing bodies, football Associations and clubs could exploit these results to take informed decisions and support evidence-based interventions during and after the Covid-19 pandemic.



#9 Automated soccer head impact exposure tracking using video and deep learning

Reference: Sci Rep. 2022 Jun 3;12(1):9282. doi: 10.1038/s41598-022-13220-2.

Authors: Ahmad Rezaei, Lyndia C Wu

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Summary: Head impacts are highly prevalent in sports and there is a pressing need to investigate the potential link between head impact exposure and brain injury risk. Wearable impact sensors and manual video analysis have been utilized to collect impact exposure data. However, wearable sensors suffer from high deployment cost and limited accuracy, while manual video analysis is a long and resource-intensive task. Here we develop and apply DeepImpact, a computer vision algorithm to automatically detect soccer headers using soccer game videos. Our data-driven pipeline uses two deep learning networks including an object detection algorithm and temporal shift module to extract visual and temporal features of video segments and classify the segments as header or nonheader events. The networks were trained and validated using a large-scale professional-level soccer video dataset, with labeled ground truth header events. The algorithm achieved 95.3% sensitivity and 96.0% precision in cross-validation, and 92.9% sensitivity and 21.1% precision in an independent test that included videos of five professional soccer games. Video segments identified as headers in the test data set correspond to 3.5 min of total film time, which can be reviewed through additional manual video verification to eliminate false positives. DeepImpact streamlines the process of manual video analysis and can help to collect large-scale soccer head impact exposure datasets for brain injury research. The fully video-based solution is a low-cost alternative for head impact exposure monitoring and may also be expanded to other sports in future work.



#10 Fatigue and Recovery Time Course After Female Soccer Matches: A Systematic Review And Meta-analysis

Reference: Sports Med Open. 2022 Jun 3;8(1):72. doi: 10.1186/s40798-022-00466-3.

Authors: Karine Naves Oliveira Goulart, Cândido Celso Coimbra, Helton Oliveira Campos, Lucas Rios Drummond, Pedro Henrique Madureira Ogando, Georgia Brown, Bruno Pena Couto, Rob Duffield, Samuel Penna Wanner

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Summary: This study aimed to analyze the extent of fatigue responses after female soccer matches and the ensuing recovery time course of performance, physiological, and perceptual responses. Three databases (PubMed, Web of Science, and SPORTDiscus) were searched in October 2020 and updated in November 2021. Studies were included when participants were female soccer players, regardless of their ability level. Further, the intervention was an official soccer match with performance, physiological, or perceptual parameters collected pre- and post-match (immediately, 12 h, 24 h, 48 h, or 72 h-post). A total of 26 studies (n = 465 players) were included for meta-analysis. Most performance parameters showed some immediate post-match reduction (effect size [ES] = - 0.72 to - 1.80), apart from countermovement jump (CMJ; ES = - 0.04). Reduced CMJ performance occurred at 12 h (ES = - 0.38) and 24 h (ES = - 0.42) and sprint at 48 h post-match (ES = - 0.75). Inflammatory and immunological parameters responded acutely with moderate-to-large increases (ES = 0.58-2.75) immediately post-match. Creatine kinase and lactate dehydrogenase alterations persisted at 72 h post-match (ES = 3.79 and 7.46, respectively). Small-to-moderate effects were observed for increased cortisol (ES = 0.75) and reduced testosterone/cortisol ratio (ES = -0.47) immediately post-match, while negligible to small effects existed for testosterone (ES = 0.14) and estradiol (ES = 0.34). Large effects were observed for perceptual variables, with increased fatigue (ES = 1.79) and reduced vigor (ES = - 0.97) at 12 h post-match, while muscle soreness was increased immediately post (ES = 1.63) and at 24 h post-match (ES = 1.00). Acute fatigue exists following female soccer matches, and the performance, physiological, and perceptual parameters showed distinctive recovery timelines. Importantly, physical performance was recovered at 72 h post-match, whereas muscle damage markers were still increased at this time point. These timelines should be considered when planning training and match schedules. However, some caution should be advised given the small number of studies available on this population.



#11 Influence of the Covid 19 pandemic on changes in aerobic fitness and injury incidence in elite male soccer players

Reference: J Sports Med Phys Fitness. 2022 Jun 10. doi: 10.23736/S0022-4707.22.13929-0. Online ahead of print.

Authors: Viswanath B Unnithan, Barry Drust, Colin Brow, Andisheh Bakhshi, Liam Mason, Matthew Weston

Summary: The SARS-COV2 agent initiated a global pandemic. The initial response to the pandemic was severe disruption to the public and private sector including sports. The resultant was that soccer clubs had to prescribe that the players trained in isolation for a prolonged period of time in an attempt to maintain fitness. The aim of the present study was to evaluate the impact of a 10-week period of training in isolation on aerobic fitness, body composition and injury incidence on the return to pre-season team-training in a group of elite, male soccer players. Twenty-two professional soccer players (age: 25.2 ± 4.4 years) who played for an English Championship first team participated in this study. A weekly training programme was sent to each player at the start of each week. Prior to the start of the isolated training period, all players underwent a maximal aerobic speed test (MAS) and body mass index data (BMI) were obtained. These measurements were repeated on the return to team training. There was a significant (p<0.05) increase in MAS pre-post isolated training (Pre: 4.71 ± 0.15 vs Post: 4.92 ± 0.17 m/s), no change in BMI (Pre: 24.3 ± 1.3 vs Post: 24.1 ± 1.1 kg/m2) and a low non-contact, soft tissue muscle incidence on the return to team training. The evidence from this study suggests that a more prolonged preseason schedule can enhance aerobic conditioning and mitigate the injury risk on the return to competitive match-play in elite soccer players.



#12 Football fans' emotional attachment to their clubs as a predictor of weight loss in a prevention programme for men with obesity

Reference: Clin Obes. 2022 Jun 10;e12540. doi: 10.1111/cob.12540.

Authors: Benjamin Pietsch, Reiner Hanewinkel, Matthis Morgenstern

Summary: Data about which factors in lifestyle interventions facilitate weight loss (WL) success in men is still scarce. The Football Fans in Training (FFIT) programme in Germany attracts men with overweight and facilitates meaningful weight reduction. The goal of this study was to evaluate the possible impact of the fans' emotional attachment to their favourite football clubs on achieving at least 5% WL among the male-only participants. All 791 FFIT intervention participants of 2017 and 2018 were included in the study. We performed two separate logistic regression analyses: (a) baseline values of several participant characteristics as predictors of a 5% WL and (b) change scores of participants' health behaviour characteristics from the course start to end as predictors of the 5% WL. In addition, both models included the Emotional Attachment to a Sports Team (EAST). Analyses were based on the intention-to-treat principle. Higher EAST at baseline was associated with WL success, as was higher WL self-efficacy, lower score in vegetable intake and higher score in food high on carbohydrates. In the second analysis, EAST, an increase in fruit intake, vegetable intake, whole-grain intake and steps per day, as well as a reduction of fatty food intake, were associated with 5% WL success. The predictors are mostly explorative and limited to correlations. The results indicate that EAST was an independent predictor of WL success in the participating football fans. This understanding might be used for tailoring future interventions in sports or similar settings.



#13 Association between Selected Screening Tests and Knee Alignment in Single-Leg Tasks among Young Football Players

Reference: Int J Environ Res Public Health. 2022 May 31;19(11):6719. doi: 10.3390/ijerph19116719.

Authors: Bartosz Wilczyński, Łukasz Radzimiński, Agnieszka Sobierajska-Rek, Katarzyna Zorena

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Summary: This study aimed to examine the relationship between knee valgus in the frontal plane projection angle (FPPA) during single-leg squat (SLS), single-leg landing (SLL), and other selected clinical tests in young athletes. Forty-three young healthy elite football players (age: 13.2 (1.7) years) that were regularly training in a local sports club participated in the study. The FPPA was assessed using 2D video analysis. The screening tests included the passive single-leg raise (PSLR), hip external and internal rotation (hip ER and IR), sit and reach test, weight-bearing lunge test (WBLT), modified star excursion balance test (mSEBT), countermovement jump (CMJ), single-leg hop for distance (SLHD), and age peak height velocity (APHV). There was a significant positive relationship between the knee valgus angles in the SLS test and the sit and reach test (r = 0.34) and a negative relationship with the hip ER ROM (r = -0.34) (p &lt; 0.05). The knee valgus angles in the SLL were negatively associated with the hip IR (r = -0.32) and ER ROM (r = -0.34) and positive associated with the WBLT (r = 0.35) and sit and reach test (r = 0.33) (p &lt; 0.05). Linear regression analysis showed that the results of the hip ER ROM and sit and reach tests were independent predictors of the FPPA in the SLS test (r2 = 0.11, p = 0.03 and r2 = 0.12, p = 0.02, respectively). The conducted study showed that individuals with more hip range of motion, more spine flexion extensibility, and less ankle dorsiflexion ROM may be more likely to experience high degrees of knee valgus in FPPA.



#14 Evaluation of an Experience of Academic Happiness through Football at University

Reference: Int J Environ Res Public Health. 2022 May 28;19(11):6608. doi: 10.3390/ijerph19116608.

Authors: David Almorza-Gomar, Rafael Ravina-Ripoll, Cristina Raluca Gh Popescu, Araceli Galiano-Coronil

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Summary: The main objective of the university sport in Spain is the comprehensive training of the students. It sets out in the various state regulations in this respect. There is training in values within the comprehensive training that sporting activity should provide through Fair Play. This article aims to describe and evaluate an experience of training in values for the university students carried out by the Sports Department of the University of Cadiz, located in Cádiz, Andalusia, Spain. The methodology consisted of making selected changes to the game rules in football competitions. The experience has lasted ten years. The result of the experience has been very positive, obtaining, among other substantial achievements, a reduction of more than 75% in the percentage of cards (yellow and red) shown during matches and a reduction in referee cautions, a decrease in violent behavior, self-exclusion of players with violent behavior by the teams themselves, and an increase in fair play sporting behavior. Due to this experience, the Sports Department of the University of Cadiz has received numerous national and international awards. However, the leading award has been to take part positively, through sport, in the education and happiness of its students.



#15 Observation on the Effect of MRI Image Scanning on Knee Pain in Football Injury

Reference: Scanning. 2022 May 25;2022:7348978. doi: 10.1155/2022/7348978. eCollection 2022.

Author: Weidong Yu

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Summary: The aim was to study the effect of football injury on knee pain based on MRI image scanning, in this paper, a total of 31 knee injuries of 29 male professional football players from December 2012 to April 2015 were used as the experimental group. The players were 23.6 ± 3.5 years old and received professional football training time 15.3 ± 3.6 years; 31 outpatients of the same age group with acute knee joint acute injury were randomly selected as the control group; both groups were imaged with a 1.5 TMR scanner and knee joint standard array coil imaging, and 2 senior radiation surgeons evaluate knee cartilage, meniscus, ligaments, tendons, bone marrow, infrapatellar fat pad, and joint effusions. Pearson's chi-squared test and nonparametric test for two independent samples were used for statistical testing of the evaluation results. The experimental results showed that there were significant differences in the incidence of articular cartilage, lateral collateral ligament, tendon or ligament injury, multiligament or tendon injury, and bone marrow edema between the two groups (P < 0.05). There was no significant difference in the incidence of medial collateral ligament injury, infrapatellar fat pad edema, and joint effusion. MRI shows that knee injuries in male professional football players often involve ligaments or tendons, mostly multiligament or tendon injuries. The lesions of articular cartilage and meniscus are more common and serious, and bone marrow edema is also more common in football injuries. MRI has high diagnostic accuracy for various clinical knee injuries, and it belongs to a noninvasive examination method. It can not only reflect the pathological changes and changes of the knee joints of patients but also provide information for the formulation of clinical programs and the judgment of prognosis, for timely, accurate, and comprehensive imaging reference.



#16 Machine Learning for Understanding and Predicting Injuries in Football

Reference: Sports Med Open. 2022 Jun 7;8(1):73. doi: 10.1186/s40798-022-00465-4.

Authors: Aritra Majumdar, Rashid Bakirov, Dan Hodges, Suzanne Scott, Tim Rees

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Summary: Attempts to better understand the relationship between training and competition load and injury in football are essential for helping to understand adaptation to training programmes, assessing fatigue and recovery, and minimising the risk of injury and illness. To this end, technological advancements have enabled the collection of multiple points of data for use in analysis and injury prediction. The full breadth of available data has, however, only recently begun to be explored using suitable statistical methods. Advances in automatic and interactive data analysis with the help of machine learning are now being used to better establish the intricacies of the player load and injury relationship. In this article, we examine this recent research, describing the analyses and algorithms used, reporting the key findings, and comparing model fit. To date, the vast array of variables used in analysis as proxy indicators of player load, alongside differences in approach to key aspects of data treatment-such as response to data imbalance, model fitting, and a lack of multi-season data-limit a systematic evaluation of findings and the drawing of a unified conclusion. If, however, the limitations of current studies can be addressed, machine learning has much to offer the field and could in future provide solutions to the training load and injury paradox through enhanced and systematic analysis of athlete data.



#17 Social and Cultural Constraints on Football Player Development in Stockholm: Influencing Skill, Learning, and Wellbeing

Reference: Front Sports Act Living. 2022 May 20;4:832111. doi: 10.3389/fspor.2022.832111. eCollection 2022.

Authors: James Vaughan, Clifford J Mallett, Paul Potrac, Carl Woods, Mark O'Sullivan, Keith Davids

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Summary: In this paper, we consider how youth sport and (talent) development environments have adapted to, and are constrained by, social and cultural forces. Empirical evidence from an 18-month ethnographic case study highlights how social and cultural constraints influence the skill development and psychological wellbeing of young football players. We utilized novel ways of knowing (i.e., epistemologies) coupled to ecological frameworks (e.g., the theory of ecological dynamics and the skilled intentionality framework). A transdisciplinary inquiry was used to demonstrate that the values which athletes embody in sports are constrained by the character of the social institutions (sport club, governing body) and the social order (culture) in which they live. The constraining character of an athlete (talent) development environment is captured using ethnographic methods that illuminate a sociocultural value-directedness toward individual competition. The discussion highlights how an emphasis on individual competition overshadows opportunities (e.g., shared, and nested affordances) for collective collaboration in football. Conceptually, we argue that these findings characterize how a dominating sociocultural constraint may negatively influence the skill development, in game performance, and psychological wellbeing (via performance anxiety) of young football players in Stockholm. Viewing cultures and performance environments as embedded complex adaptive systems, with human development as ecological, it becomes clear that microenvironments and embedded relations underpinning athlete development in high performance sports organizations are deeply susceptible to broad cultural trends toward neoliberalism and competitive individualism. Weaving transdisciplinary lines of inquiry, it is clarified how a value directedness toward individual competition may overshadow collective collaboration, not only amplifying socio-cognitive related issues (anxiety, depression, emotional disturbances) but simultaneously limiting perceptual learning, skill development, team coordination and performance at all levels in a sport organization.



#18 Genetic associations with technical capabilities in English academy football players: a preliminary study

Reference: J Sports Med Phys Fitness. 2022 Jun 6. doi: 10.23736/S0022-4707.22.13945-9. Online ahead of print.

Authors: Alexander B McAULEY, David C Hughes, Loukia G Tsaprouni, Ian Varley, Bruce Suraci, Joseph Baker, Adam J Herbert, Adam L Kelly

Summary: Technical capabilities have significant discriminative and prognostic power in youth football. Although, many factors influence technical performance, no research has explored the genetic contribution. As such, the purpose of this study was to examine the association of several single nucleotide polymorphisms (SNPs) with technical assessments in youth football players. Fifty-three male under-13 to under-18 outfield football players from two Category 3 English academies were genotyped for eight SNPs. Objective and subjective technical performance scores in dribbling, passing, and shooting were collated. Simple linear regression was used to analyse individual SNP associations each variable, whereas both unweighted and weighted total genotype scores (TGSs; TWGSs) were computed to measure the combined influence of all SNPs. In isolation, the ADBR2 (rs1042714) C allele, BDNF (rs6265) C/C genotype, DBH (rs1611115) C/C genotype, and DRD1 (rs4532) C allele were associated with superior (8-10%) objective dribbling and/or shooting performance. The TGSs and/or TWGSs were significantly correlated with each technical assessment (except subjective passing), explaining up to 36% and 40% of the variance in the objective and subjective assessments, respectively. The results of this study suggest inter-individual genetic variation may influence the technical capabilities of youth football players and proposes several candidate SNPs that warrant further investigation.



#19 A Study on the Optimization and Improvement of the Construction of the Campus Football Development Model by a Factor Analysis Method under the Background of "Healthy China"

Reference: J Environ Public Health. 2022 May 26;2022:3260571. doi: 10.1155/2022/3260571. eCollection 2022.

Authors: Zhen Wang, Bin Tan, Binquan Yi

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Summary: In order to enrich campus sport life and promote the development of campus ball game, this paper uses the analysis method to analyze the development mode of campus football and evaluates the relevant factors combined with the development status, characteristics, and future trend of campus football. Factor analysis is a comprehensive analysis method, which can realize multifactor comprehensive analysis and qualitative and quantitative analysis of campus football. At the same time, analyze the relationship between various factors and find a scheme conducive to the development of campus football. The results show that both comprehensive method factors and single method factors are positive, indicating that the two models have a significant positive impact on the development model of students' football. However, the influence degree of the comprehensive method (0.314) is the largest, followed by the single method factor (0.128), and the sig. values of the two variable factors are <0.05, so the comprehensive method is the main mode of campus football development. Therefore, the factor analysis method proposed in this paper is conducive to the selection of campus football development model and provides support for the development of campus football.



#20 COVID-19 Diffusion Before Awareness: The Role of Football Match Attendance in Italy

Reference: J Sports Econom. 2022 Jun;23(5):503-523. doi: 10.1177/15270025211067786.

Authors: Vincenzo Alfano

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Summary: Anecdotal evidence suggests that football matches may have played a role in the spread of COVID-19 all over Europe. Nevertheless, from a scientific point of view, the impact of football matches on the spread of COVID-19 remains unclear. In this paper we study, via a quantitative analysis, the case of Italy, a country badly affected by COVID, and one where attending football matches is very popular. We consider the impact of matches played in January and February 2020 on the dynamic of the pandemic in March and April the same year. Our results, which consider all levels of Italian professional football, and the highest level of amateur football, show that matches played in January and February had an impact on the evolution of the pandemic in March and April. These results suggest that great care must be taken before considering re-opening stadia.



#21 Prognostic factors of muscle injury in elite football players: A media-based, retrospective 5-year analysis

Reference: Phys Ther Sport. 2022 May 27;55:305-308. doi: 10.1016/j.ptsp.2022.05.009. Online ahead of print.

Authors: Jan Wilke, Sarah Tenberg, David Groneberg

Summary: Motor function has been demonstrated to be weakly predictive for the occurrence of muscle injury in team sports. This study examined the value of non-motor prognostic factors in elite football (soccer). 1148 players of 38 German and English first-division football clubs. Binary logistic regression examining the association of prognostic factors (age, height, weight, BMI, playing position, market value, history of injury, number of played matches and minutes) and time-loss muscle injuries sustained during five consecutive seasons (2014/2015 to 2018/2019). A total of 1722 muscle injuries were observed in 619 players. History of general musculoskeletal injury (OR 5.3, 95% CI 3.8-7.5), playing position (OR 2.4-2.5), market value (OR 2.3, 95% CI 1.7-3.1), and history of muscle injury (OR 1.6, 95% CI 1.1-2.2) were associated with muscle injury. Sub-analyses revealed location-specific patterns. Playing position was not predictive for adductor injury and, except for one weak association (defender vs. goalkeeper: OR 1.05, 95%CI 0.42-2.62), the same applied to the calf. Contrary to other locations, thigh re-injury was not predicted by previous muscle injury. Non-motor factors display significant associations with injury risk in elite football players. Conditioning coaches may use this information to improve primary and secondary prevention, while scouting departments may benefit during recruitment.



#22 Differential Ratings of Perceived Exertion: Relationships With External Intensity and Load in Elite Men's Football

Reference: Int J Sports Physiol Perform. 2022 Jun 3;1-10. doi: 10.1123/ijspp.2021-0550. Online ahead of print.

Authors: Kobe C Houtmeyers, Pieter Robberechts, Arne Jaspers, Shaun J McLaren, Michel S Brink, Jos Vanrenterghem, Jesse J Davis, Werner F Helsen

Summary: The aim was to examine the utility of differential ratings of perceived exertion (dRPE) for monitoring internal intensity and load in association football. Data were collected from 2 elite senior male football teams during 1 season (N = 55). External intensity and load data (duration × intensity) were collected during each training and match session using electronic performance and tracking systems. After each session, players rated their perceived breathlessness and leg-muscle exertion. Descriptive statistics were calculated to quantify how often players rated the 2 types of rating of perceived exertion differently (dRPEDIFF). In addition, the association between dRPEDIFF and external intensity and load was examined. First, the associations between single external variables and dRPEDIFF were analyzed using a mixed-effects logistic regression model. Second, the link between dRPEDIFF and session types with distinctive external profiles was examined using the Pearson chi-square test of independence. On average, players rated their session perceived breathlessness and leg-muscle exertion differently in 22% of the sessions (range: 0%-64%). Confidence limits for the effect of single external variables on dRPEDIFF spanned across largely positive and negative values for all variables, indicating no conclusive findings. The analysis based on session type indicated that players differentiated more often in matches and intense training sessions, but there was no pattern in the direction of differentiation. The findings of this study provide no evidence supporting the utility of dRPE for monitoring internal intensity and load in football.



#23 Effects of Low vs Moderate Dose of Recreational Football on Cardiovascular Risk Factors

Reference: Eur J Sport Sci. 2022 Jun 6;1-19. doi: 10.1080/17461391.2022.2086488. Online ahead of print.

Authors: Roberto Modena, Franco M Impellizzeri, Alessandro Fornasiero, Federico Schena

Summary: This study aimed to compare the effectiveness of recreational football performed once (LOW) vs. twice (MOD) a week on cardiovascular risk factors in healthy, sedentary men. Body composition, resting blood pressure, blood lipid profile and maximal oxygen consumption (VO2max) were measured at baseline, after a 12-week control and training period, using an interrupted time series study (study 1, n=18: n=8, LOW and n=10, MOD) nested in a randomised parallel trial (study 2, n=34: n=18 LOW and n=16 MOD). After the intervention in the study 1, LDL-Cholesterol (-12.3 mg•dL-1 [-22.7 to -2.0]) and VO2max (4.5 ml•kg-¹•min-¹ [1.2 to 7.8 ]) changed in LOW whereas differences were found in weight (-2.1 kg [-3.7 to -0.4]), BMI (-0.7 kg•m-2 [-1.2 to -0.1]), total cholesterol (-22.2 mg•dL-1 [-36.0 to -8.4]), no-HDL-cholesterol (-17.5 mg•dL-1 [-30.5 to -4.5]), LDL-cholesterol (-14.9 mg•dL-1 [-23.6 to -6.2]) and VO2max (5.7 ml•kg-¹•min-¹ [2.8 to 8.6]) in MOD. Study 2 showed no evidence of differences between groups. Our results therefore, suggest positive health effects of recreational football even when performed at low frequency as it can happen in real context.


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