Latest research in football - week 5 - 2021

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 Implementing High-speed Running and Sprinting Training in Professional Soccer

Reference: Int J Sports Med. 2020 Dec 8. doi: 10.1055/a-1302-7968. Online ahead of print. 

Authors: Marco Beato, Barry Drust, Antonio Dello Iacono

Summary: High-speed running and sprinting training play an important role in the development of physical capabilities, sport-specific performance and injury prevention among soccer players. This commentary aims to summarize the current evidence regarding high-speed running and sprinting training in professional soccer and to inform its implementation in research and applied settings. It is structured into four sections: 1) Evidence-based high-speed running and sprinting conditioning methodologies; 2) Monitoring of high-speed running and sprinting performance in soccer 3) Recommendations for effective implementation of high-speed running and sprinting training in applied soccer settings; 4) Limitations and future directions. The contemporary literature provides preliminary methodological guidelines for coaches and practitioners. The recommended methods to ensure high-speed running and sprinting exposure for both conditioning purposes and injury prevention strategies among soccer players are: high-intensity running training, field-based drills and ball-drills in the form of medium- and large-sided games. Global navigation satellite systems are valid and reliable technologies for high-speed running and sprinting monitoring practice. Future research is required to refine, and advance training practices aimed at optimizing individual high-speed running and sprinting training responses and associated long-term effects. 



#2 The association between perceptual-cognitive processes and response time in decision making in young soccer players

Reference: J Sports Sci. 2020 Dec 7;1-10. doi: 10.1080/02640414.2020.1851901. 

Authors: Felippe da Silva Leite Cardoso, José Afonso Neves, André Roca, Israel Teoldo

Summary: In soccer, it is relevant to understand the roles of Systems 1 (intuitive) and 2 (deliberative) in perceptual-cognitive processes and how they influence response time when making decisions. The aim of this study was to analyse how response time in decision making managed by Systems 1 and 2 is associated to the perceptual-cognitive processes of young soccer players. Ninety young soccer players participated. Perceptual-cognitive processes were assessed through visual search strategies, cognitive effort, and verbal reports. Participants wore a mobile-eye tracking system while viewing 11-a-side match play video-based soccer simulations. Response time in decision making was used to create two sub-groups: faster and slower decision-makers. Results indicated that players with faster response time in decision making employed more fixations of shorter duration, displayed less cognitive effort, as well as a greater number of thought processes associated with planning. These results reinforce that there are differences in the way of using the perceptive-cognitive processes from the priority system in the decision-making process. It is concluded that faster decision making, managed by System 1, implies greater ability to employ visual search strategies and to process information, thus enabling increased cognitive efficiency. 



#3 Long-term Stress Distribution Patterns Across the Ankle Joint in Soccer Players: A Computed Tomography Osteoabsorptiometry Study 

Reference: Orthop J Sports Med. 2020 Nov 19;8(11):2325967120963085. doi: 10.1177/2325967120963085. eCollection 2020 Nov. 

Authors: Junki Shiota, Daisuke Momma, Takayoshi Yamaguchi, Norimasa Iwasaki

Summary: The distribution pattern of subchondral bone density is considered to accurately reflect the stress distribution over a joint under long-term physiologic loading. The biomechanical characteristics of the surface of the ankle joint in soccer players can be determined by measuring this distribution pattern under long-term loading. The purpose was to evaluate the distribution of subchondral bone density across the ankle joint in soccer players and to determine the effects of soccer activities, including kicking motion, on the ankle joint surface under long-term loading conditions by computed tomography (CT) osteoabsorptiometry (CTOAM). CT imaging data were obtained from both ankles of 10 soccer players (soccer group) and 10 nonathletic volunteers (control group). The distribution patterns of subchondral bone density across the articular surface of the ankle joints were assessed by CTOAM. Quantitative analysis was performed of the locations and percentages of high-density areas on the articular surface. Stress distribution patterns over the ankle joint differed between the soccer players and controls. In the soccer players, the high-density areas were found in the anterior part of the distal tibia and proximal talus as well as the distal fibula. The percentages of high-density areas were greater in the soccer players compared with controls (P < .0001). Stress distribution over the articular surface of the ankle joint was affected by soccer activities. A high stress concentration was seen in soccer players in the anterior part of the tibia and talus and in the fibula; such excessive stress may lead to anterior impingement. 



#4 The financial and performance cost of injuries to teams in Australian professional soccer

Reference: J Sci Med Sport. 2020 Nov 26;S1440-2440(20)30813-6. doi: 10.1016/j.jsams.2020.11.004. 

Authors: Donna Lu, Alan McCall, Mark Jones, Jeff Steinweg, Les Gelis, Job Fransen, Rob Duffield

Summary: The aim was to determine the relationship between injury incidence, player-salary cost and team performance in the professional Australian soccer league. Injury incidence, player-salary cost and team performance data were collected from the 10-club A-League competition (n=27 matches/season) over 6 seasons from 2012/13. Player-salary cost of injury was calculated from the salary cap, injury-induced missed matches and player exposure, and trends were reported from Poisson regressions. Team performance was determined from ranking, points, goals (scored, conceded and difference) and match outcome (win, loss or draw) per season and analysed via a mixed-effects Poisson models to estimate association with injury. Nine-hundred-and-sixteen injuries resulted in 3148 missed matches. Injury incidence remained stable apart from a decrease in 2015/16 (p=0.01). Missed matches were significantly higher in season 2013/14 (55.1 [50.7-59.9]; p<0.01) and 2014/15 (71.4 [66.4-76.8]; p<0.001) compared to 2012/13, without differences between other seasons. Player-salary cost ranged between AUD$187,990-AUD$332,680/team, peaking in 2014/15 (p<0.01). Multi-collinearity was detected for team performance variables except for matches lost. Teams who finished the season with greater positive goal differences were associated with 1% less injuries (p=0.003). Similarly, more missed matches were associated with 1% less league points and losses (p<0.001). Player-salary costs remained stable, concomitant with stable injury rates and missed matches. Despite injury being associated with goals difference, points and match losses; the magnitude of these relationships are small and team performance is more complex than injury occurrence alone. Injury prevention remains necessary for reducing injury-induced player-salary costs; however, additional services are required to improve team performance. 



#5 A Novel Method to Categorize Stretch-Shortening Cycle Performance Across Maturity in Youth Soccer Players

Reference: J Strength Cond Res. 2020 Dec 3. doi: 10.1519/JSC.0000000000003900. Online ahead of print. 

Authors: Jason S Pedley, Rhodri S Lloyd, Paul J Read, Isabel S Moore, Gregory D Myer, Jon L Oliver

Summary: This study used a novel method to categorize stretch-shortening cycle (SSC) function during a drop jump (DJ) using the force-time curve. This method was then used to determine the effect of maturity status upon SSC function and effect of SSC function on DJ performance. Prepeak, circa-peak, and postpeak height velocity male youth soccer players completed a preseason 30-cm DJ onto a force plate. Stretch-shortening cycle function was categorized as poor (impact peak and not spring-like), moderate (impact peak and spring-like), or good (no impact peak and spring-like). Interactions between SSC function and maturity status, and SSC function and kinetic variables were explored. Youth soccer players displaying good SSC function were older and more mature than those with poor SSC function; however, 9.9% of post peak height velocity still displayed poor SSC function. Players with good SSC function recorded significantly shorter ground contact times, reduced time between peak landing and takeoff force, reduced center of mass displacement, and significantly greater takeoff forces than players with moderate and poor SSC function (all p < 0.05). SSC function during a standardized DJ improves with maturation, but a portion of mature players still demonstrate poor SSC function. Good SSC function was associated with improved DJ outcome measures except jump height. Tailored training interventions based on SSC competency may be required to optimally enhance SSC function. 



#6 Inspiratory Muscle Training Improves Aerobic Capacity in Amateur Indoor Football Players

Reference: Int J Sports Med. 2020 Dec 11. doi: 10.1055/a-1255-3256. 

Authors: Matheus Martins de Sousa, Matheus Dos Santos Pimentel, Isabela de Andrade Sobreira, Rondineli de Jesus Barros, Audrey Borghi-Silva, Flavia Mazzoli-Rocha

Summary: Inspiratory muscle training represents a recommended clinical practice to improve physical performance of healthy individuals, athletes, and those with chronic diseases. This study aimed to evaluate whether high- and low-intensity inspiratory muscle training interferes with the aerobic capacity of indoor soccer players. Volunteers were equally and randomly divided into CON (control group, no inspiratory muscle training); HIG (high-intensity group, inspiratory muscle training at 80% of maximal inspiratory pressure, 3 sets of 12 repetitions); and LIG (low-intensity group, inspiratory muscle training at 50% of maximal inspiratory pressure, 2 sets of 20 repetitions). Before and after inspiratory muscle training, maximal inspiratory and expiratory pressures, the incremental shuttle run test, and the 3-min step test were evaluated. Both inspiratory muscle training protocols improved maximal inspiratory and expiratory pressures, and indirect maximal oxygen consumption and distance traveled in the shuttle test compared to CON. However, only HIG achieved significant increases of indirect oxygen consumption and frequency of step rise in the 3-min step test (p<0.05). Inspiratory muscle training is an important tool to enhance maximal inspiratory pressure and exercise tolerance with potential benefits on submaximal aerobic capacity. However, high-intensity inspiratory muscle training improved aerobic capacity in amateur indoor soccer players in both submaximal tests. 



#7 Association Between Proteomic Blood Biomarkers and DTI/NODDI Metrics in Adolescent Football Players: A Pilot Study

Reference: Front Neurol. 2020 Nov 16;11:581781. doi: 10.3389/fneur.2020.581781. eCollection 2020. 

Authors: Keisuke Kawata, Jesse A Steinfeldt, Megan E Huibregtse, Madeleine K Nowak, Jonathan T Macy, Kyle Kercher, Devin J Rettke, Andrea Shin, Zhongxue Chen, Keisuke Ejima, Sharlene D Newman, Hu Cheng 

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Summary: While neuroimaging and blood biomarker have been two of the most active areas of research in the neurotrauma community, these fields rarely intersect to delineate subconcussive brain injury. The aim of the study was to examine the association between diffusion MRI techniques [diffusion tensor imaging (DTI) and neurite orientation/dispersion density imaging (NODDI)] and brain-injury blood biomarker levels [tau, neurofilament-light (NfL), glial-fibrillary-acidic-protein (GFAP)] in high-school football players at their baseline, aiming to detect cumulative neuronal damage from prior seasons. Twenty-five football players were enrolled in the study. MRI measures and blood samples were obtained during preseason data collection. The whole-brain, tract-based spatial statistics was conducted for six diffusion metrics: fractional anisotropy (FA), mean diffusivity (MD), axial/radial diffusivity (AD, RD), neurite density index (NDI), and orientation dispersion index (ODI). Five players were ineligible for MRIs, and three serum samples were excluded due to hemolysis, resulting in 17 completed set of diffusion metrics and blood biomarker levels for association analysis. Our permutation-based regression model revealed that serum tau levels were significantly associated with MD and NDI in various axonal tracts; specifically, elevated serum tau levels correlated to elevated MD (p = 0.0044) and reduced NDI (p = 0.016) in the corpus callosum and surrounding white matter tracts (e.g., longitudinal fasciculus). Additionally, there was a negative association between NfL and ODI in the focal area of the longitudinal fasciculus. Our data suggest that high school football players may develop axonal microstructural abnormality in the corpus callosum and surrounding white matter tracts, such as longitudinal fasciculus. A future study is warranted to determine the longitudinal multimodal relationship in response to repetitive exposure to sports-related head impacts. 



#8 The Influence of Basic Psychological Needs and Passion in Promoting Elite Young Football Players' Development

Reference: Front Psychol. 2020 Nov 16;11:570584. doi: 10.3389/fpsyg.2020.570584. eCollection 2020. 

Authors: José L Chamorro, Rubén Moreno, Tomás García-Calvo, Miquel Torregrossa

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Summary: Motivational variables and cognitive skills have been identified as important in an athlete's development. The aim of this study is to explore the influence of each basic psychological needs satisfaction on player's development regarding reflection and concentration disruption with the mediation of types of passion in Spanish young elite football players. A total of 487 elite U18 male football players (Mage = 17.43, SD = 0.71) completed measures of basic psychological needs satisfaction, passion for football, reflective thinking, and concentration disruption. Measurement models were defined using exploratory structural equation models. The results provide support for the model, where each psychological needs satisfaction prompted reflection and had a negative influence on concentration disruption with the mediation of harmonious passion. In addition, obsessive passion mediated the positive relationship between competence satisfaction and concentration disruption. Finally, competence and relatedness satisfaction influenced the development of reflection directly and positively and, exclusively, relatedness satisfaction had a negative influence in a direct way on concentration disruption. In sum, our results highlight that (a) the environment of young footballers through psychological needs satisfaction has a positive (i.e., reflection) or negative (i.e., concentration disruption) influence on the field, but only with the mediation of harmonious passion, (b) in a competitive environment, the perception of competence can have a positive influence on concentration disruption, but only with the development of obsessive passion as a mediator, and (c) relatedness satisfaction plays a key role in distinguishing between reflection and concentration disruption. 



#9 Outbreak of community-acquired Staphylococcus aureus skin infections in an Australian professional football team

Reference: J Sci Med Sport. 2020 Nov 20;S1440-2440(20)30815-X. doi: 10.1016/j.jsams.2020.11.006.

Authors: Ramon Z Shaban, Cecilia Li, Matthew V N O'Sullivan, Jen Kok, Kathy Dempsey, Marc Ramsperger, Mitchell Brown, Shizar Nahidi, Cristina Sotomayor-Castillo

Summary: Skin and soft tissue infections commonly affect athletes and can lead to cluster outbreaks if not managed appropriately. We report the findings of an investigation into an outbreak of community-acquired Staphylococcus aureus infection in an Australian professional football team. Nose, axilla, groin and throat swab were collected from 47 participants. MRSA and MSSA isolates underwent antibiotic susceptibility testing, binary typing and whole genome sequencing. Infection control practitioners (ICPs) investigated the training grounds for risk factors in the transmission of S. aureus. Almost half of the participants (n=23, 48.9%) were found to be colonised with MSSA. An outbreak cluster of MRSA ST5 closely related to the fusidic acid-resistant New Zealand NZAK3 clone was identified in a group of four players. MSSA ST15 and MSSA ST291 strains were found to have colonised and spread between two and five players, respectively. All participants were advised to undergo decolonisation treatment consisting of 4% chlorhexidine body wash and mupirocin nasal ointment for ten days. The ICP team identified several unhygienic practices within the club's shared facilities that may have played a role in the transmission of S. aureus. We report for the first time a community-associated S. aureus outbreak involving the highly successful fusidic acid-resistant MRSA ST5 clone in a professional football club associated with inadequate hygiene procedures. Management and prevention of S. aureus relies heavily on hygiene education and adherence to personal and environmental hygiene practices and policies. 



#10 Illness and infection in elite full-contact football-code sports: A systematic review

Reference: J Sci Med Sport. 2020 Nov 10;S1440-2440(20)30810-0. doi: 10.1016/j.jsams.2020.11.001. 

Authors: Lucy Chesson, Sarah Whitehead, Kirsten Flanagan, Kevin Deighton, Jamie Matu, Susan H Backhouse, Ben Jones

Summary: Full-contact football-code team sports offer a unique environment for illness risk. During training and match-play, players are exposed to high-intensity collisions which may result in skin-on-skin abrasions and transfer of bodily fluids. Understanding the incidence of all illnesses and infections and what impact they cause to time-loss from training and competition is important to improve athlete care within these sports. This review aimed to systematically report, quantify and compare the type, incidence, prevalence and count of illnesses across full-contact football-code team sports. A systematic search of Cochrane Library, MEDLINE, SPORTDiscus, PsycINFO and CINAHL electronic databases was performed from inception to October 2019; keywords relating to illness, athletes and epidemiology were used. Studies were excluded if they did not quantify illness or infection, involve elite athletes, investigate full-contact football-code sports or were review articles. Twenty-eight studies met the eligibility criteria. Five different football-codes were reported: American football (n=10), Australian rules football (n=3), rugby league (n=2), rugby sevens (n=3) and rugby union (n=9). One multi-sport study included both American football and rugby union. Full-contact football-code athletes are most commonly affected by respiratory system illnesses. There is a distinct lack of consensus of illness monitoring methodology. Full-contact football-code team sport athletes are most commonly affected by respiratory system illnesses. Due to various monitoring methodologies, illness incidence could only be compared between studies that used matching incidence exposure measures. High-quality illness surveillance data collection is an essential component to undertake effective and targeted illness prevention in athletes. 



#11 Factors influencing optimum countermovement jump performance and movement strategy in Championship professional football players: implications for player profiling

Reference: Res Sports Med. 2020 Dec 10;1-11. doi: 10.1080/15438627.2020.1860049. Online ahead of print. 

Authors: Andy Mitchell, Craig Holding, Matt Greig

Summary: Single leg countermovement jump (CMJ) is a common profiling test influenced by sport, age, sex and playing level. Controlling for these confounding variables, outfield players from an English Championship squad (n = 36) were retrospectively categorized as best (n = 10) or worst (n = 10), based on mean single leg CMJ height and flight time:contraction time ratio. Movement strategy was quantified as force-time history metrics differentiating eccentric and concentric phases. Jump height revealed that best performers elicited greater rate of force development in both phases (P ≤ 0.033), with concentric impulse the strongest predictor of performance. Time ratio also differentiated best performers as utilizing a shallower (P = 0.002) countermovement, with concentric rate of force development the strongest predictor of good performance. Successful jump height performance can mask ineffectual eccentric and stretch shortening cycle neuromuscular characteristics. Time ratio is therefore advocated as the key performance indicator, with movement strategy prioritized over gross outcome measures. 



#12 Effects of football versus aerobic exercise training on muscle architecture in healthy men adults: a study protocol of a two-armed randomized controlled trial 

Reference: Trials. 2020 Dec 9;21(1):1007. doi: 10.1186/s13063-020-04797-y. 

Authors: Guevar Alkhateeb, Lars Donath

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Summary: Sports and exercise training can attenuate age-related declines in physical function. As people age, they suffer a progressive deterioration of overall muscle structure and function, such as muscle diameter, strength, mass, and power. Therefore, supporting older adults-aged 50 years and above-to continue being physically active is a very important factor. Several forms of exercise (strength, agility, endurance, balance, and flexibility) are recommended. In this regard, football has been repeatedly shown to be an integrative approach to promote measures of strength, endurance, and agility. However, there has been no previous randomized controlled trial that comparatively investigates the effects of football training versus traditional aerobic exercise training on muscle architecture and patella tendon properties in healthy community dwellers. The study protocol is designed to examine whether football differentially affects muscle thickness, muscle length, fascicle length, pennation angle, patella tendon length, and thickness compared to a workload matched traditional aerobic exercise training regimen. The study sample consists of 60 untrained but healthy men (50-60 years old), who will be randomly assigned (strata: age, activate) to two groups: football group (n = 30) and aerobic group (n = 30). The intervention will take place within 12 consecutive weeks, two times a week for 60 min each session. The football group will perform recreational football training as a large-sided game, whereas the aerobic group undergoes a running exercise. Both groups have the same external workload ranging between moderate and high exercise intensity. The outcome measure will be collected before and after the intervention period. Findings of this study will provide insight into the effects of 24 sessions of both football and aerobic training program on the selected groups of men adults, including detecting their effects on the thigh muscle architecture. 



#13 Financial Performance Analysis in European Football Clubs

Reference: Entropy (Basel). 2020 Sep 21;22(9):1056. doi: 10.3390/e22091056. 

Authors: David Alaminos, Ignacio Esteban, Manuel A Fernández-Gámez

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Summary: The financial performance of football clubs has become an essential element to ensure the solvency and viability of the club over time. For this, both the theory and the practical and regulatory evidence show the need to study financial factors, as well as sports and corporate factors to analyze the possible flow of income and for good management of the club's accounts, respectively. Through these factors, the present study analyzes the financial performance of European football clubs using neural networks as a methodology, where the popular multilayer perceptron and the novel quantum neural network are applied. The results show the financial performance of the club is determined by liquidity, leverage, and sporting performance. Additionally, the quantum network as the most accurate variant. These conclusions can be useful for football clubs and interest groups, as well as for regulatory bodies that try to make the best recommendations and conditions for the football industry. 



#14 Spatial and Temporal Entropies in the Spanish Football League: A Network Science Perspective

Reference: Entropy (Basel). 2020 Feb 2;22(2):172. doi: 10.3390/e22020172. 

Authors: Johann H Martínez, David Garrido, José L Herrera-Diestra, Javier Busquets, Ricardo Sevilla-Escoboza, Javier M Buldú

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Summary: We quantified the spatial and temporal entropy related to football teams and their players by means of a pass-based interaction. First, we calculated the spatial entropy associated to the positions of all passes made by a football team during a match, obtaining a spatial entropy ranking of Spanish teams during the 2017/2018 season. Second, we investigated how the player's average location in the field is related to the amount of entropy of his passes. Next, we constructed the temporal passing networks of each team and computed the deviation of their network parameters along the match. For each network parameter, we obtained the permutation entropy and the statistical complexity of its temporal fluctuations. Finally, we investigated how the permutation entropy (and statistical complexity) of the network parameters was related to the total number of passes made by a football team. Our results show that (i) spatial entropy changes according to the position of players in the field, and (ii) the organization of passing networks change during a match and its evolution can be captured measuring the permutation entropy and statistical complexity of the network parameters, allowing to identify what parameters evolve more randomly. 


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