Latest research in football - week 38 -2023

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 Significant Changes in Resting Metabolic Rate Over a Competitive Match Week Are Accompanied by an Absence of Nutritional Periodization in Male Professional Soccer Players

Reference: Int J Sport Nutr Exerc Metab. 2023 Sep 21;1-11.  doi: 10.1123/ijsnem.2023-0069. Online ahead of print.

Authors: Jennie L Carter, David J Lee, Craig G Perrin, Mayur K Ranchordas, Matthew Cole

Summary: Resting metabolic rate (RMR) is an important component of total daily energy expenditure; however, it is currently not understood how it varies across a typical competitive match week in professional soccer players. For the first time, we aimed to assess RMR throughout an in-season competitive week in professional soccer players. Additionally, we aimed to assess energy and carbohydrate intake across the same week. Twenty-four professional soccer players from an English Premier League club (age: 18 ± 1.6 years) completed the study. RMR was assessed each morning of a typical competitive match week (match day [MD] -3, -2, -1, +1, +2, and + 3), and dietary intake (including MD) was assessed daily via the remote food photography method and 24-hr recall. Daily training load was quantified using Global Positioning System, daily muscle soreness ratings were recorded, and body composition was assessed via dual-energy X-ray absorptiometry. There was a significant (p = .0004) increase in mean RMR of ∼261 kcal/day on MD + 1, compared with MD - 1. Additionally, volume of oxygen consumed significantly increased at MD + 1 (p = .0002) versus MD - 1. There were no significant differences in daily energy or carbohydrate intake across the competitive week (p > .05), with inadequate carbohydrate intakes on MD - 1 (∼3.9 g/kg body mass), MD (∼4.2 g/kg body mass), and MD + 1 (∼3.6 g/kg body mass) in relation to current recommendations. We report, for the first time, that RMR is significantly increased following a competitive match in professional soccer players. In addition, we confirm previous findings to reinforce that players exhibit inadequate nutrition periodization practices, which may impair physical performance and recovery.



#2 Elite North American soccer performance in thermally challenging environments: An explorative approach to tracking outcomes

Reference: J Sports Sci. 2023 Sep 21;1-8. doi: 10.1080/02640414.2023.2259262. Online ahead of print.

Authors: Garrison Draper, Greg Atkinson, Paul Chesterton, Matthew Portas, Matthew Wright

Summary: The physiologic challenges related to performances in hot conditions calls for dedicated consideration when planning athlete training, although complete amelioration of the effects of heat may not be possible. We aimed to quantify within-subject correlations between different measures of environmental temperature and performance changes over multiple elite soccer competitions. Thirty-seven elite male soccer players (age: 26 ± 3.4 years, height: 171 ± 2 cm, body mass: 78 ± 7.1 kg) competed in North America over four seasons (range: 3 to 98 matches). Players wore global positioning system devices during games and reported differential-RPE immediately post game. Temperatures at kick-off, week average temperature, the difference between game-day and week average (DiffTemp), and heat index at kick-off were obtained. Within-player correlations were calculated using general linear models to quantify associations between fluctuations in temperature measures and physical and perceived outputs. Correlations between total distance and the various temperature measures were trivial to small (range: -0.08 to 0.13, p=<0.001-0.02). Small negative correlations were found between all temperature measures except DiffTemp and high-speed running (HSR) (range: -0.17 to -0.14, p=<0.001). Most correlations between differential-RPE and temperature measures were trivial to small and not significant (r = 0.06 to 0.18 p = 0.03-0.92) although breathlessness-RPE and heat index showed a small significant association (P = 0.018). Decrements in HSR appear to be associated with increased environmental temperature, however, these associations are small in magnitude.



#3 Improved physical performance of elite soccer players based on GPS results after 4 days of carbohydrate loading followed by 3 days of low carbohydrate diet

Reference: J Int Soc Sports Nutr. 2023 Dec;20(1):2258837. doi: 10.1080/15502783.2023.2258837. Epub 2023 Sep 20.

Authors: Abdolreza Kazemi, Ghazi Racil, Amir Hossein Ahmadi Hekmatikar, Mohadeseh Behnam Moghadam, Parisa Karami, Menno Henselmans

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Summary: Carbohydrate loading is an established sports nutrition strategy for endur- 16 ance exercise performance. We tested if carbohydrate loading could improve the performance of 17 elite soccer players under ecologically valid circumstances using Global Positioning System (GPS) data. Twenty-two adult Iran Premier league soccer players were divided into a carbohydrate-loading group (CLG) and Control group (CG). The carbohydrate loading group restricted carbohydrate intake for three days to 1.5 g/kg/d while increasing exercise intensity. From days four to seven, exercise intensity was decreased and carbohydrate intake was considerably increased up to 7.5 g/kg/d on the day of the match, during which performance was analyzed using GPS data. The control group performed the same exercise training but maintained their habitual carbohydrate intake of 5-6 g/kg/d. The data were analyzed using a univariate ANCOVA with baseline data from a pre-intervention match as the control variable. The carbohydrate loading team scored significantly higher on running distance, maximum speed and the number of top and repeated sprints; the carbohydrate loading group scored significantly lower on player load, metabolic power and running imbalance compared to the control team during their match. Our findings suggest carbohydrate loading enabled elite soccer players to achieve greater running outputs with greater metabolic efficiency and lower fatigue compared to their habitual diets.



#4 Imaging-detected sports injuries and imaging-guided interventions in athletes during the 2022 FIFA football (soccer) World Cup

Reference: Skeletal Radiol. 2023 Sep 16. doi: 10.1007/s00256-023-04451-z. Online ahead of print.

Authors: Marcelo Bordalo, Andreas Serner, Eduardo Yamashiro, Emad Al-Musa, Mohamed Abdelatif Djadoun, Khalid Al-Khelaifi, Yorck Olaf Schumacher, Abdulaziz Jaham Al-Kuwari, Andrew Massey, Pieter D'Hooghe, Marco Cardinale

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Summary: The aim was to describe imaging-detected musculoskeletal injuries and image-guided interventional procedures during the 2022 FIFA football (soccer) World Cup. Retrospective analysis of all radiologic examinations performed in a central medical facility for athletes was performed by two board certified musculoskeletal radiologists. Data on muscle, tendon, ligament, cartilage, and bone injuries were collected according to imaging modality and body part. A total of 143 radiology examinations in 94 athletes were evaluated at the central medical facility. Magnetic resonance imaging (MRI) was the most utilized modality (67%), followed by radiography (12%), ultrasonography (9%), and computed tomography (4%). Image-guided interventions corresponded to 8% of all radiological examinations. There were 112 injuries described, affecting muscles and tendons (42%), ligaments (25%), cartilage (21%), and bone (12%). Most injured body parts were thigh (27%), foot and ankle (23%), knee (23%), and hip/groin (8%). Most injured players were within the age range of 24-35 years old (71%). Imaging was utilized in 11% of players who participated in the 2022 FIFA World Cup in Qatar. MRI was the most utilized modality, and acute muscle tears were the most diagnosed type of injury. Diagnostic imaging played an important role in diagnosing sports-related injuries during the 2022 FIFA World Cup.




#5 FIFA football nurse - A task sharing approach in sports and exercise medicine practice in grassroots women's football in low- and middle- income settings. A study protocol for a cluster randomised controlled trial

Reference: PLoS One. 2023 Sep 21;18(9):e0278428. doi: 10.1371/journal.pone.0278428. eCollection 2023.

Authors: Nonhlanhla Sharon Mkumbuzi, Andrew Massey, Samuel Kiwanuka Lubega, Ben Sorowen, Enock Madalitso Chisati

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Summary: Football (soccer) is a very popular team sport among African women and girls, with player numbers continuing to rise at all levels of the sport. Whereas the participation in football and associated injuries are on the rise, there are not enough sports and exercise medicine (SEM) personnel to attend to these women football players. While Africa may not currently have enough SEM trained medical doctors and/or physiotherapists, it has relatively higher numbers of other healthcare workers; for example, nurses, who lead healthcare services provision from community to tertiary levels. The primary objective of this study will be to compare sports medicine practices; injury prevention behaviours; injury risk parameters; incidence and prevalence of injuries and illnesses in teams with and without a Football Nurse during one competitive season in Malawi's Women's football league. This study will be a cluster randomised control trial will recruit 24 teams from the Women's Football League in Malawi, which will be randomised to either the intervention group or the control group. A cohort of 12 nurses will receive training in basic football medicine; after which they will be attached to a total of 12 women's football teams (intervention group) during one competitive season. The Football Nurses will be directly report to a physiotherapist or doctor in their district to whom they will refer serious injuries for investigations, or further management. The teams with Football Nurses will be compared to other teams that will not have Football Nurses. We expect to develop a low cost, sustainable and context relevant solution to manage the treatment gap of football injuries/illnesses in underserved communities such as women's football. Trial registration number: Pan African Clinical Trial Registry (PACTR202205481965514).



#6 The assessment of the match performance of association football referees: Identification of key variables

Reference: PLoS One. 2023 Sep 21;18(9):e0291917. doi: 10.1371/journal.pone.0291917. eCollection 2023.

Authors: Vítor Carvalho, Pedro T Esteves, Célia Nunes, Werner F Helsen, Bruno Travassos

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Summary: The purpose of this study was to understand the contribution of each performance indicator to evaluate match performance of football referees. Thirty-four elite Referee Match Observers (RMOs) from the Portuguese FA participated voluntarily in the study. From the official assessment sheet of each game, the referee's game score was categorized in two groups according to referee's game score: i) Referees with a Low Score (LFS) and ii) Referees with High Score (HFS). A multivariable binary logistic regression model was used to assess the relationship between the Performance Indicators (PIs) of the dimensions i) game difficulty and game intervention and ii) disciplinary actions and game management in relation to the referee's match assessment score. The model proposed revealed that only the PIs negative application of the laws of the game and referee teamwork, from the dimension disciplinary actions and game management, significantly defined the final game referee's assessment score. This study suggests that the PIs scored by the RMOs contributed in a different way to the referee's game score. The model explains 60.4% of the referee's game score based on the variables referee teamwork and negative application of the laws of the game.



#7 Bonitation assessment of intensively used football turf depending on the date and area of observation

Reference: Sci Rep. 2023 Sep 20;13(1):15580. doi: 10.1038/s41598-023-42562-8.

Authors: Karol Wolski, Łukasz Sobol, Henryk Bujak

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Summary: This article aimed to evaluate the visual and functional characteristics of intensively used football turf over 10 years, depending on the different areas of the game. The research was conducted on the football turf of the AZS Environmental Club in Wrocław (N: 51° 7' 31'' E:17° 4' 14''). High variability of the evaluated parameters was observed regarding seasonality, year of observation, and the area of play. It has been shown that the goal area and penalty box areas have the lowest functional value, which are vital areas of the game from the point of view of gaining an advantage in the game. Also, these places are more susceptible to creating sites without plants (requiring additional overseeding) due to the potential of hollowing and goalkeeper interventions ending with the body landing on the ground. The middle area was characterized by the highest overall aspect, color, and turf density values. In the vast majority of cases, there was a downward trend in the turfs' functional value with the turf's age, which is an essential finding in the context of the use of intensively used, athletic natural grass surfaces.



#8 Can the Copenhagen Adduction Exercise Prevent Groin Injuries in Soccer Players? A Critically Appraised Topic

Reference: J Sport Rehabil. 2023 Sep 21;1-4. doi: 10.1123/jsr.2023-0088. Online ahead of print.

Authors: Marcos Quintana-Cepedal, Omar de la Calle, Hugo Olmedillas

Summary: Injuries that affect the groin region are among the most common in football players. To prevent this condition, studies have focused on strengthening the adductors, hip flexors, or abdominal muscles. Recent investigations have used an eccentric-biased exercise (Copenhagen Adduction Exercise [CAE]) that promotes functional and architectural adaptations in the muscle tissue, though its effect on injury risk reduction is unknown. Can the Copenhagen Adduction Exercise prevent groin injuries in soccer players, was the research question. The literature was searched for studies investigating the potential groin injury risk reduction effect of the CAE. (1) Three studies met the inclusion criteria and were used for this appraisal; (2) one study observed a significantly lower injury rate ratio favoring the group that used the CAE program; and (3) 2 studies found similar or higher injury rates in the intervention groups, not supporting the inclusion of the CAE as a preventative tool. There is conflicting evidence that usage of the CAE is superior to not performing adductor strengthening exercises in mitigating the risk of sustaining groin injuries. Given the evidence supporting these findings, it is advisable to exercise caution when contemplating the incorporation of the CAE into training regimens aimed at preventing groin injuries.



#9 Dental injuries in Swiss soccer supporters: A comparative study of regular fans, ultras, and hooligans for public health strategies

Reference: Clin Exp Dent Res. 2023 Sep 21. doi: 10.1002/cre2.783. Online ahead of print.

Authors: Clarissa Schneider, Michelle Simonek, Florin Eggmann, Andreas Filippi

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Summary: Violence among soccer supporters continues to pose a significant public health concern in many parts of the world. In Switzerland, hooliganism is largely uninvestigated. This study aimed to examine incidents of violence and associated dental injuries among different groups of soccer supporters, as well as assess the impact of intoxicants on their behavior, using survey data from regular fans, ultras, and hooligans in the Swiss Football League. A cross-sectional survey using a standardized questionnaire was conducted among distinct factions of soccer supporters in the Swiss Football League in 2022. A total of 165 participants self-identified as belonging to one of three subgroups: "regular fan," "ultra," or "hooligan." Data were gathered on physical altercations, dental injuries, possession of mouthguards, intoxicant use, and medical assistance. Descriptive statistics, logistic regression models, and significance tests were used for data analysis (α = .05). Hooligans had a higher frequency of dental injuries resulting from fights than ultras and regular fans. Hooligans with 11-20 fights per soccer season had a 9.6 times higher probability of dental trauma than those with 0-5 fights (p = .048). Possession of a mouthguard was associated with a lower risk of dental injuries for hooligans but an increased risk for ultras. Additionally, hooligans were found to differ significantly from other groups in their consumption of amphetamines and cocaine (p < .001). The study found a strong link between physical altercations and dental injuries among soccer supporters. To promote better prevention, there is a necessity for enhanced educational initiatives facilitated by dentists to amplify the dissemination of mouthguards. Furthermore, it is crucial to raise awareness regarding their proper fitting to minimize the occurrence of combat-related dental injuries. Health authorities and other stakeholders should take a comprehensive approach to addressing some of the root causes of violent behavior, which include alcohol abuse and illicit substance consumption.



#10 Daytime sleepiness in Chinese professional, semi professional and students soccer players in the Shanghai lockdown

Reference: BMC Sports Sci Med Rehabil. 2023 Sep 22;15(1):119. doi: 10.1186/s13102-023-00730-3.

Authors: Songhui You, Antonio Cicchella

Summary: April-May 2021 Shanghai city was under strict lockdown. Soccer players suffered from the restrictions, being unable to train and have a social life. The aim of this study was to compare differences in daytime sleepiness between genders and qualification levels in a cohort university Chinese soccer player under 0 Covid policy restrictions in the urban area of Shanghai. 491 questionnaires of Epworth Sleepiness Scales (ESS) were compiled online by male and female Soccer Students (SS), Semi-Professional players (SP) and Professional Players (PP) during the ongoing restriction measures post Shanghai lockdown. ANOVA was performed for players levels and gender. Significant differences were found between the 3 levels and between males and females. PP showed a very low score in the ESS (5,97) well below the threshold of 8 for daytime sleepiness, while SS and SP showed an ESS score above the threshold. Female showed higher scores in comparison to males. Differences between males and females reflect the confinement conditions in the ESS items, showing more difference in the item of ESS which are related with indoor situations. This study shows the first data on sleepiness in Chinese soccer players of different level of qualification immediately post lockdown condition. Professional male's players sleepiness was lower, than females, SS and SP after the exceptional lockdown measures. The reasons can reside in the more ordered lifestyle of PP in comparison to SS and SP, which mitigated the effects of the lockdown. Our results suggest that measures to improve sleep in females' soccer player should be adopted if these exceptional conditions will happen again.



#11 The relationship of player load and anaerobic performance in different football playing strategies

Reference: Physical Education of Students, 2023;27(4):190–200.

Authors: Erol M, Kapelman AE, Kızılet A. 

Summary: The purpose of the present study is to determine the effect of player load on the anaerobic performance of soccer players. Eighty Turkish Super League U21 players (age:19.56±1.3 years, height: 180.3±2.1cm, weight: 75.9±3.7kg) were involved in this study. The players completed eight different 11v11 training games. While one team practiced the ball possession and “defense as a team” strategy, the other team implemented the counterattacking strategy. The formation was kept as “4-4-2”. The games were played as 2x20-min training matches. Maximum heart rate, player load, ratings of perceived exertion, high running speed, and sprint performances were analyzed. Pearson’s correlation analysis was used in determining the level of correlation between quantitative variables. Linear regression analyses were carried out to examine the effect of player load on anaerobic performance components in different strategies and positions. Compared to tactical strategy, player load values were found to be different from all positions. It was observed that maximum hearth rate, ratings of perceived exertion, high running speed, and sprint data were correlated with player load data (p<0.05). Given the results achieved from the regression analysis, it was determined that an increase in player load data caused an increment in these data. In conclusion, it was observed that player load data affect position-specific anaerobic performance in football. It is thought that the use of the data related to player load, acceleration, and deceleration in the training planning in accordance with the positions of players and the team strategies will increase the performance of the athlete.



#12 Individual Locating of Soccer Players from a Single Moving View

Reference: Sensors (Basel). 2023 Sep 16;23(18):7938. doi: 10.3390/s23187938.

Authors: Adrien Maglo, Astrid Orcesi, Julien Denize, Quoc Cuong Pham

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Summary: Positional data in team sports is key in evaluating the players' individual and collective performances. When the sole source of data is a broadcast-like video of the game, an efficient video tracking method is required to generate this data. This article describes a framework that extracts individual soccer player positions on the field. It is based on two main components. As in broadcast-like videos of team sport games, the camera view moves to follow the action and a sport field registration method estimates the homography between the pitch and the frame space. Our method estimates the positions of key points sampled on the pitch thanks to an encoder-decoder architecture. The attention mechanisms of the encoder, based on a vision transformer, captures characteristic pitch features globally in the frames. A multiple person tracker generates tracklets in the frame space by associating, with bipartite matching, the player detections between the current and the previous frames thanks to Intersection-Over-Union and distance criteria. Tracklets are then iteratively merged with appearance criteria thanks to a re-identification model. This model is fine-tuned in a self-supervised way on the player thumbnails of the video sample to specifically recognize the fine identification details of each player. The player positions in the frames projected by the homographies allow the obtaining of the real position of the players on the pitch at every moment of the video. We experimentally evaluate our sport field registration method and our 2D player tracker on public datasets. We demonstrate that they both outperform previous works for most metrics. Our 2D player tracker was also awarded first place at the SoccerNet tracking challenge in 2022 and 2023.



#13 Preliminary Baseline Vestibular Ocular Motor Screening Scores in Pediatric Soccer Athletes

Reference: J Sport Rehabil. 2023 Sep 27:1-7. doi: 10.1123/jsr.2022-0327. Online ahead of print.

Authors: Morgan Anderson, Christopher P Tomczyk, Aaron J Zynda, Alyssa Pollard-McGrandy, Megan C Loftin, Tracey Covassin

Summary: The utility of baseline vestibular and ocular motor screening (VOMS) in high school and collegiate athletes is demonstrated throughout the literature; however, baseline VOMS data at the youth level are limited. In addition, with the recent adoption of the change scoring method, there is a need to document baseline VOMS total and change scores in a pediatric population. To document baseline VOMS total and change scores and to document the internal consistency of the VOMS in pediatric soccer athletes. We hypothesized that the VOMS would demonstrate strong internal consistency in pediatric soccer athletes. Pediatric soccer athletes (N = 110; range = 5-12 y) completed the VOMS at baseline. Descriptive statistics summarized demographic information, VOMS total scores, and VOMS change scores. Cronbach α assessed internal consistency for VOMS total scores and change scores. Twenty-one (19.1%) participants had at least one total score above clinical cutoffs (≥2 on any VOMS component and ≥5 cm on average near point convergence). Forty (36.4%) participants had at least one change score above clinical cutoffs (≥1 on any VOMS component and ≥3 cm on average near point convergence). The internal consistency was strong for total scores with all VOMS components included (Cronbach α = .80) and change scores (Cronbach α = .89). Although results suggest VOMS items measure distinct components of the vestibular and ocular motor systems, caution should be taken when interpreting VOMS total and change scores in pediatric athletes, as overreporting symptoms is common, thereby impacting the false-positive rate.



#14 Street soccer and homelessness: Exploring social identities, health, and well-being

Reference: Psychol Sport Exerc. 2023 Sep 3:70:102529. doi: 10.1016/j.psychsport.2023.102529. Online ahead of print.

Authors: Joseph J O'Rourke, Andrea Bundon, Guy Faulkner, Tegan Cruwys, Mark R Beauchamp

Summary: Membership in social and physical activity groups has the potential to help people with a range of physical and mental health challenges. The purpose of this study was to examine the experiences of members of a unique physical activity group: people who were formerly or currently homeless participating in a street soccer program in Western Canada. Ten participants in the Vancouver Street Soccer League (VSSL) were interviewed about the extent to which this program fostered a sense of community, social connectivity, and quality of life among people with experience of homelessness. Interviews were augmented with a Social Identity Mapping activity and observations from the first author who took part in weekly practice with the VSSL for over a year. The data were analysed using thematic analysis, in which four themes were developed to reflect the findings. These included (1) Coming together through soccer, (2) Dynamics motivating continued involvement in the league, (3) Leaders and leadership: Social influence in the league, and (4) The league and health outcomes. The findings provide insight into how a street soccer program which fostered shared social identity, psychological safety, friendly competition, and social support contributed to the well-being of people impacted by homelessness, various traumas, and marginalisation.



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