Latest research in football - week 30 - 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 Is ball-possession style more physically demanding than counter-attacking? The influence of playing style on match performance in professional soccer

Reference: Front Psychol. 2023 Jul 7;14:1197039. doi: 10.3389/fpsyg.2023.1197039. eCollection 2023.

Authors: Leon Forcher, Leander Forcher, Hagen Wäsche, Darko Jekauc, Alexander Woll, Timo Gross, Stefan Altmann

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Summary: In soccer, the offensive style of play describes characteristic behavioral features of the players at team level during the offensive phase of matches. This study aimed to investigate the effect of offensive playing style (i.e., while in ball possession) on physical and technical match performance during offensive play as well as success-related factors. The sample consisted of official tracking and event data of 153 matches of the 2020/21 German Bundesliga season. For every team in every match an offensive playing style coefficient was calculated to locate teams on a continuum between ball possession and counter-attacking style. This calculation contains 11 technical and physical performance parameters and has already been validated. In addition, dependent physical (e.g., sprinting distance), technical (e.g., passes), and success-related (e.g., goals) variables were examined. A separate linear mixed model was calculated for each dependent variable. While teams with lower playing style coefficient values (= counter-attacking style) covered more high-intensity (p ≤ 0.01; R2 = 0.13) and sprinting distances per second in possession (p ≤ 0.01; R2 = 0.14), teams with higher playing style coefficient values (= ball possession style) were physically more demanded over a whole match (e.g., more accelerations (p ≤ 0.01; R2 = 0.69), decelerations (p ≤ 0.01; R2 = 0.69), high-intensity (p ≤ 0.01; R2 = 0.36), sprint distance (p = 0.03; R2 = 0.08)). Furthermore, teams with higher playing style coefficient values played more horizontal passes (p ≤ 0.01; R2 = 0.73) and revealed better passing success rates (p ≤ 0.01; R2 = 0.17). In contrast, teams with lower playing style coefficient values played more long passes (p < 0.01; R2 = 0.58). The influence of the playing style coefficient on success-related variables was smaller (p ≤ 0.36; R2 = 0.10-0.13). Concluding, offensive playing style affects physical and technical match performance, but has limited influence on success. Hence, coaches can use the findings to optimize training contents to prepare players for the physical demands of a match.



#2 Building Bridges Instead of Putting Up Walls: Connecting the "Teams" to Improve Soccer Players' Support

Reference: Sports Med. 2023 Jul 22. doi: 10.1007/s40279-023-01887-0. Online ahead of print.

Authors: João Renato Silva, Martin Buchheit, Karim Hader, Hugo Sarmento, José Afonso

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Summary: The increase in the economic value of soccer occurred in parallel with an increase in competing demands. Therefore, clubs and federations evolved to greater specialization (e.g., state-of-the-art facilities and high-profile expertise staff) to support players' performance and health. Currently, player preparation is far from exclusively club or national team centered, and the lack of control in each player's environment can be more prevalent than expected. For example, an elite group of professional players faces disruptions in the season club-oriented planification due to involvement in national teams. Moreover, as elite players' financial resources grow, it is common for them to employ specialized personal staff (e.g., strength and conditioning, nutritionist, and sports psychologist) to assist in their preparation, resulting in complex three-fold relationships (i.e., club, player's staff, national team). Although efforts have been made to improve communication with and transition from the club to the national team supervision, this new reality (club-players' staff) may generate serious compound role-related problems and difficulties in monitoring load and training adaptation and having a unified message. Therefore, efforts must be implemented to ensure a more informed management of the players' performance environment, where the existence and impact of these various personal staff are considered to avoid a long-term non-zero sum for all intervening parties. If left unchecked, current professional thinking may collide or overlap, potentially triggering conflict escalation and impairing athletic performance or health, especially if effective communication routes are not adequately established. Moreover, diluted personal responsibility regarding performance may ensue, resulting in decreased productivity from all involved, which may cause more harm than benefits for the player's overall health and performance. This emerging reality calls for developing a joint working framework (i.e., between the player's personalized support team and the clubs' team) and better managing of a player-centered process.



#3 A 3-min weighted vests re-warmups induce sprint performance enhancements at the start of the second half of a soccer match-play

Reference: Front Physiol. 2023 Jul 6;14:1173991. doi: 10.3389/fphys.2023.1173991. eCollection 2023.

Authors: Mohamed Amine Ltifi, Olfa Turki, Ghazi Racil, Alin Larion, Mohamed Souhaiel Chelly, Helmi Ben Saad, Riadh Khalifa, Karim Chamari, Johnny Padulo

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Summary: This study aimed to investigate the effect of re-warm-up (RWUP) activities consisting of three sets of 15-m sprints with weighted vests on 20-m sprint performance after the break. Using a randomized, and counterbalanced cross-over design, twenty U15 elite soccer players performed four RWUP trials which consisted of 15-min of passive rest (control: CONT), 3 × 15-m sprint (RW0%), sprinting with a vest-loaded at 5% of body-mass (BM) (RW5%), sprinting with a 10% BM vest (RW10%). The 3-min RWUP protocols started 10-min after the commencement of the 15-min between-halves break and concluded 2-min before its end. During each testing session, the participant's RPE scores, and 20-m sprint performance were registered before the first half, and at the end of the break of the simulated match-play. Significant time effects [F (1.72) = 54.37, d = 1.88, p < 0.001; F (1.72) = 9.07, d = 0.77, p = 0.003], and condition effects [F (3.72) = 11.81, d = 1.53, p < 0.001; F (3.72) = 7.36, d = 1.21, p = 0.003] were observed for RPE scores and 20-m sprint performance, respectively. Significant condition-by-time interactions were found for RPE scores (p < 0.003, d = 0.54), and 20-m sprint performance (p < 0.002, d = 0.70). Contrast analysis showed significantly higher RPE scores (p < 0.001, d = 1.55), and improved 20-m sprint performance (p = 0.0004, d = 1.19) in the RW10% condition compared to all other conditions. Sprinting for 3-min with a 10% body-mass vest resulted in the highest RPE scores and the most substantial enhancements in 20-m sprint performance. Young elite soccer players should incorporate 10% body-mass weighted vests in their re-warm-ups to boost post-break sprint performance.



#4 Adductor longus and brevis lesion in an amateur soccer player: platelet rich plasma and multifractioned hyaluronic acid injections to enhance clinical recovery

Reference: J Sports Med Phys Fitness. 2023 Jul 24. doi: 10.23736/S0022-4707.23.14938-3. Online ahead of print.

Authors: Silvana Giannini, Sebastiano Vasta, Arrigo Giombini, Chiara Fossati, Ugo Riba, Giuseppe Massazza, Rocco Papalia, Fabio Pigozzi

Summary: Groin pain is a common issue in athletes, with a particularly high incidence in male soccer players. Adductor muscles are the most involved site of the groin, accounting for up to one-fourth of muscle injuries of that region. Physical therapy and rehabilitation programs for adductor-related groin pain using active exercises are effective in getting athletes back to sport. However, the return-to-play time varies according to the injury severity. Minor lesions can recover in 1-2 weeks, while severer injuries require 8-12 weeks. To enhance tendon healing and shorten the return to play time, intrandentinous injections of Platelet Rich Plasma (PRP) have been proposed. An increasing body of evidence in literature have shown efficacy of platelet rich plasma in aiding the healing process in tendinopathies. Similarly, more recent evidences have proven hyaluronic (HA) acid to have anti-inflammatory, proliferative, repairing, and analgesic effects. This case report presents the clinical application of combined PRP and a multifractioned (a mixture of different molecular weights) HA in a 24-year-old athlete suffering from a hip adductor rupture.



#5 Effects of Resistance Training of Upper Limb and Trunk Muscles on Soccer Instep Kick Kinematics

Reference: J Appl Biomech. 2023 Jul 24;1-10. doi: 10.1123/jab.2022-0323. Online ahead of print.

Authors: Miguel Arcanjo de Assis, Thiago Ribeiro Teles Santos, Sergio Teixeira Fonseca, André Gustavo Pereira de Andrade, Priscila Albuquerque Araújo, Thales Rezende de Souza, Renan Alves Resende, Juliana Melo Ocarino

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Summary: The upper body and trunk muscles are crucial to perform soccer kicks. Resistance training targeting these muscles may modify the pattern adopted during kicking. This study aimed to investigate the effect of resistance training of the arm and anterior trunk muscles on instep kicking kinematics. Twenty-six male participants were randomly allocated into a training group or control group. The training group underwent resistance training of arm and trunk muscles and practiced the instep kick for 8 weeks. The control group only practiced kicking during the same period. The trunk, hip, and knee kinematics were assessed during the instep kick before and after the intervention. Kinematics were analyzed according to their data distribution with statistical parametric or nonparametric mapping. The effect of the training on the 1-repetition maximum test was analyzed using a repeated-measures multivariate analysis of variance. The training group showed greater hip extension after the training during the backswing phase (Hedge g effect size of 0.316-0.321) and increased 1-repetition maximum for all exercises. There were no other differences. The present study documented the nonlocal effect of strengthening training in which arm and trunk muscle training resulted in changes in hip kinematics during the backswing phase of the instep kick.



#6 Morphological Characteristics of Elite International Soccer Referees: Somatotype and Bioelectrical Impedance Vector Analysis

Reference: J Funct Morphol Kinesiol. 2023 Jul 24;8(3):100. doi: 10.3390/jfmk8030100.

Authors: Pascal Izzicupo, Cristian Petri, Sofia Serafini, Giorgio Galanti, Gabriele Mascherini

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Summary: This study aimed to assess the physical characteristics of elite international soccer referees, compare them with other referee populations in the literature, and establish reference tolerance ellipses for the bioelectrical impedance vector analysis (BIVA) point graph. Forty-one elite international soccer referees (age 38.8 ± 3.6 years) participated in the study. The participants underwent body composition assessments, including dual-energy X-ray absorptiometry, BIVA, and somatotype. The Somatotype Attitudinal Distance (SAD), the two-sample Hotelling's T2 test and the Mahalanobis test were used to determine somatotype and bioelectrical vector differences with the literature. The average somatotype of the referees was a balanced mesomorph (2.8, 6.5, 2.8). Elite international referees significantly differed from other samples in the literature (SAD = 2.1, 2.6, 2.9 with respect to Zimbabwean, Brazilian, and South African referees, respectively). The bioelectrical vector was significantly different from the general population (T2 ≤ 76.6; F = 38.8; D = 1.44; p < 0.001) and athletes (T2 ≤ 25.3; F = 12.6; D = 0.8; p < 0.001). Somatotype values and tolerance ellipses from this study may be useful as a reference for developing training programs and improving the selection process of referees in soccer.



#7 Mental toughness among national soccer officials: A comparative analysis

Reference: J Public Health Afr. 2022 Dec 7;13(Suppl 2):2423. doi: 10.4081/jphia.2022.2423.

Authors: Mahabir Nath, Vikas Singh, Anshuman Mishra

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Summary: Few studies have looked at the psychological mechanisms that govern soccer officials' performance to this point. The main goal of the study is to identify age-related changes in mental toughness among officials. Sixty active national officials were chosen at random from the All-India Football Federation's national officials' roster (AIFF). Group A is 25-30 years old, with a mean and SD of 27.4±3.39 (lower age group); Group B is 31-35 years old, with a mean and SD of 31.8±1.28 (middle age group); and Group C is 36-40 years old, with a mean and SD of 37.6±1.98 (higher age group). The Psychological Performance Inventory (PPI), developed by James E. Loehr in 1982, was chosen as the research's test item. This instrument evaluates seven aspects of mental toughness, including selfconfidence, negative energy control, attention control, visualisation and imagery control, motivation, positive energy control, and attitude control. One-way analysis of variance (ANOVA), with a significance threshold of 0.05, was used as the statistical approach to assess the study's hypothesis. The finding of the research paper shows no significant difference among various groups.



#8 Pilot Study: The Relationship between Foot Posture and Movement Quality in Non-Professional Male Football Players

Reference: Life (Basel). 2023 Jul 17;13(7):1574. doi: 10.3390/life13071574.

Authors: José Algaba-Del-Castillo, Aurora Castro-Méndez, Ana Juana Pérez-Belloso, José Gabriel Garrido-Barragán, Alberto Aguilar Sánchez, Manuel Coheña-Jiménez

Summary: This study focusses on establishing the relationship between quality of movement (based on the functional movement screen, or FMS) and foot posture (based on the foot posture index, or FPI-6). We hypothesised that a poor FMS test score may be derived from the foot position in the space measured by FPI-6. A quasi-experimental and cross-sectional study was designed to analyse foot posture in 30 healthy football players, using the foot posture index and the functional movement screen. No significant relationships were found between movement quality and foot posture. Poor movement quality is present in more than half of all foot positions, supination, pronation, and neutral. Good quality seems to be more associated with a neutral foot position (23.3%) and supinated (16.6%) than a pronated foot position (6.6%). This study found no relationship between the two tests; therefore, we cannot demonstrate that foot posture is relevant in the quality of the movement of the football players studied.



#9 Maturity-Associated Polygenic Profiles of under 12-16-Compared to under 17-23-Year-Old Male English Academy Football Players

Reference: Genes (Basel). 2023 Jul 12;14(7):1431. doi: 10.3390/genes14071431.

Authors: Alexander B T McAuley, Ian Varley, Adam J Herbert, Bruce Suraci, Joseph Baker, Kathryn Johnston, Adam L Kelly

Summary: The purpose of this study was to examine polygenic profiles previously associated with maturity timing in male academy football players across different age phases. Thus, 159 male football players from four English academies (U12-16, n = 86, aged 13.58 ± 1.58 years; U17-23, n = 73, aged 18.07 ± 1.69 years) and 240 male European controls were examined. Polygenic profiles comprised 39 single nucleotide polymorphisms and were analysed using unweighted and weighted total genotype scores (TGSs; TWGSs). There were significant differences in polygenic profiles between groups, whereby U17-23 players had more genetic variants associated with later maturity compared to U12-16 players (TGS, p = 0.010; TWGS, p = 0.024) and controls (TGS, p = 0.038; TWGS, p = 0.020). More specifically, U17-23 players had over two-times the odds of possessing >36 later-maturing alleles than <30 compared to U12-16 players (odds ratio (OR) = 2.84) and controls (OR = 2.08). These results suggest there was a greater proportion of relatively later-maturing players as maturation plateaus towards adulthood, which may be explained by the 'underdog hypothesis'. This study provides the first known molecular evidence that supports the notion that a maturity selection bias exists within male academy football.



#10 Dropping Out or Continuing Playing-A Case Study of Adolescent's Motives for Participation in Football

Reference: Sports (Basel). 2023 Jul 3;11(7):128. doi: 10.3390/sports11070128.

Authors: Jostein Bergin, Pål Lagestad

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Summary: The purpose of this study was to investigate dropout and continuation motives among boys in youth football. Semi-structured interviews were conducted with all players from a former football team, consisting of 13 young people who were 17 years old when the in-depth interviews were conducted. Short interviews with the same players five years earlier (at the age of 12) were also included as part of the data. This strategy was used to gain a longitudinal perspective and a better insight into the participants' experience of organized football. Including in-depth data from all players at a football team-both players that dropped out and continued playing football, and also including some short interviews data from a longitudinal perspective, this study bring new findings into the discussion about sport participation. When the in-depth interviews were conducted, six of the participants had dropped out of football, while seven were still active. The results show that social factors, ambition, other interests and differences in skill and physical development, were all reasons for dropout from this team. Among those who continued playing football, the social aspect of football, their love for the sport, competitive instinct and the training benefits the sport provided, were reasons they continued playing. Furthermore, the findings showed that those who reported the lowest ambitions at the age of twelve, had dropped out of football, while the one with the highest ambitions had continued playing football. Our findings indicate that ambition can be a crucial factor in relation to participation in football, and also that the social aspect of football is an important motivational factor that coaches and parents should be aware of.



#11 Retracted: Research on Video Target Detection and Tracking in Football Matches

Reference: Comput Intell Neurosci. 2023 Jul 19;2023:9801425. doi: 10.1155/2023/9801425. eCollection 2023.

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#12 Commotio Cordis Returns…When We Least Expected It: Cardiac Arrest in A Professional Football Player

Reference: Am J Cardiol. 2023 Jul 24;S0002-9149(23)00396-X. doi: 10.1016/j.amjcard.2023.06.027.

Authors: Barry J Maron, N A Mark Estes

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Summary: For the first time in 52 years, an American professional football player (Damar Hamlin) collapsed in cardiac arrest during a game, viewed in real-time on national television. The cause of this profound event was commotio cordis, that is, blunt non-penetrating chest blow-initiated ventricular fibrillation triggered by physical contact not considered unusual for football. The athlete survived because of timely cardiopulmonary resuscitation and defibrillation provided by first responders organized by the National Football League. Commotio cordis, albeit rare, was most prominently identified initially in competitive and also recreational sports participants. More recently it became apparent that similar events could occur in almost any circumstance involving a chest blow, such as during everyday activities around the home and with innocent play. The determinant of a commotio cordis event is a blow over the heart in a narrow vulnerable electrical window during dispersion of repolarization. Survival from these events has increased substantially to >60% due to enhanced recognition and prompt resuscitation/defibrillation. In conclusion, in this commentary, we take a timely opportunity to describe in detail the relevant demographics, mechanism/pathophysiology, and clinical course of commotio cordis.



#13 Protective guidelines and mitigation strategies for hot conditions in professional football: starting 11 Hot Tips for consideration

Reference: BMJ Open Sport Exerc Med. 2023 Jul 21;9(3):e001608. doi: 10.1136/bmjsem-2023-001608. eCollection 2023.

Authors: Vincent Gouttebarge, Rob Duffield, Steve den Hollander, Ron Maughan

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Summary: Elevated heat, humidity and solar load combined with low air movement independently and additively impair performance, increase the perception of effort and the risk of heat-related illnesses. For the specific context of professional football, the Fédération Internationale de Football Association (FIFA) heat guidelines are often used as the default policy. Still, these seem less protective than guidelines in other sports or from countries traditionally exposed to extreme hot conditions. Following several high-profile international and continental competitions played in hot conditions (eg, 2014 FIFA World Cup Brazil), a series of cross-sectional studies showed that national team players and their managers unanimously mentioned that the hot and humid conditions during these matches made it difficult as a team to perform. Such a concern is likely to be relevant for the upcoming 2026 FIFA World Cup that will be held in the traditional June-July window across 16 host cities in Canada, Mexico and USA. Therefore, to better protect players' health and performance during training and match play in hot conditions, we present our starting 11 Hot Tips that should be considered and facilitated by governing bodies, competition organisers, clubs, staff members and players.



#14 Disagreement between talent scouts: Implications for improved talent assessment in youth football

Reference: J Sports Sci. 2023 Jul 25;1-8. doi: 10.1080/02640414.2023.2239614. Online ahead of print.

Authors: Dennis Lüdin, Lars Donath, Michael Romann

Summary: Reliable talent identification and selection (TID) processes are prerequisites to accurately select young athletes with the most potential for talent development programmes. Knowledge about the agreement between scouts who play a key role in the initial TID in football is lacking. Therefore, the aim of the present study was to evaluate the agreement within four groups of a total of n = 83 talent scouts during rank assessment of under-11 male youth football players (n = 24, age = 11.0 ± 0.3 years) and to describe scouts' underlying approach to assess talent. Krippendorff's α estimates indicated disagreement of scouts' rankings within all groups of scouts (αA = 0.09, αB = 0.03, αC = 0.05, αD = 0.02). Scouts reported relying mainly on their overall impression when forming their final prediction about a player. Reportings of a consistent, structured approach were less prevalent. Taken together, results indicated that different approaches to TID may be associated with disagreement on selection decisions. In order to overcome disagreement in TID, football organisations are encouraged to establish a more structured process. Future research on the elaboration and benefit of ranking guidelines incorporating decomposed and independently evaluated sub-predictors is recommended to improve the reliability of TID.



#15 Leadership in Finnish elite football: associations between players' self-assessed leadership roles and player-assessed head coach leadership behavior by player gender and age

Reference: Sci Med Footb. 2023 Jul 25;1-7. doi: 10.1080/24733938.2023.2237483. Online ahead of print.

Authors: Sakari Holopainen, Mihály Szeróvay, Niilo Konttinen, Marja Kokkonen

Summary: We investigated the associations between Finnish top tier footballers' self-assessed leadership roles (task, motivational, social, external) and player-assessed head coach leadership behavior (supportiveness/emotional composure, negative activation) and leadership role in both practices and games. We also explored the player age- and gender-related differences. Online survey data were anonymously collected from 53 male and 91 female footballers. One player did not identify as male or female, and one chose not to answer the question. Spearman rank-order correlations revealed that players' self-assessed leadership roles correlated positively with their evaluation of their head coach's supportiveness/emotional composure and negatively with negative activation during practices and games. Independent samples T-tests showed that male footballers rated their head coaches lower on negative activation during games and practices and themselves higher on external leadership than female players. The youngest age group, aged 17-20, rated themselves also lower on external leadership than the three older groups.



#16 Analysis of microbiota profile and nutritional status in male professional football players

Reference: J Sports Med Phys Fitness. 2023 Jul 24. doi: 10.23736/S0022-4707.23.15103-6. Online ahead of print.

Authors: Emre B Kenger, Fatih Eren, Tugce Ozlu, Fatma E Gunes

Summary: The interest in the effect of gut microbiota on athlete health has increased in recent years. Available data indicate a relationship between gut microbiota composition and physical activity, suggesting that changes in the microbiota may contribute to the host's physical performance. Studies show that leaky gut syndrome is highly correlated with upper respiratory infections and gastrointestinal disorders in endurance sports. This study aims to reveal the relationship between microbiota profiles, and the nutritional status of football players who perform endurance exercises. Twenty male professional football players playing in one of the Turkish Football Federation Second League clubs participated in the study. Fecal samples were collected and stored at -86 °C, and the fecal microbiota was analyzed through 16s rRNA gene sequencing. The body composition of the football players was measured using a bioelectrical impedance analyzer. In addition, the 3-day food intake of the participants was recorded with the help of a dietitian. In the microbiota of football players, four phyla, 10 genera, and four species with densities above 1% were found. Body fat percentage was observed to be negatively correlated with the species of Faecalibacterium prausnitzii and Bacteroides vulgatus and the genus of Faecalibacterium (P<0.05). Considering the nutritional status, the fat intake was found to be positively correlated with Actinobacteria and Blautia coccoides; energy and fiber intake with Prevotella and Prevotella copri (P<0.05). In addition, there was a negative correlation between carbohydrate intake and Faecalibacterium (P<0.05). Our study is the first to reveal the microbiota profile of professional Turkish football players. It was found that football players' nutritional status and anthropometric measurements of are significantly related to phylum, genus and species ranks in the microbiota. These results support the bidirectional interaction between microbiota and sports. The relationship between microbiota and sports health/performance is thought to be further clarified with future studies.



#17 How the 12th Man Influences Football Matches: The Role of Fans and Referees in Home Advantage Phenomenon

Reference: Percept Mot Skills. 2023 Jul 24;315125231191683. doi: 10.1177/00315125231191683.

Authors: Ali Işın, Miguel Ángel Gómez Ruano

Summary: Home advantage and referee bias are two sport factors that have been widely studied in the football (i.e., soccer) context. However, the mediating effect of spectators on these factors is not well understood, especially in the Turkish Super League. We examined (a) how variables of home advantage, referee bias, and spectator presence interacted to affect the outcome of past football matches; (b) how these variables have changed over time in the Turkish Super League; (c) and whether home advantage and referee bias differ in matches with spectators and ghost matches (without spectators). We analyzed regular season matches played in the Turkish Super League between the 2014-2015 and 2021-2022 seasons. We found that home teams had a significant advantage over away teams in matches with spectators (p < .001) and in ghost matches (p < .05 and p < .001), with small to medium effect sizes (d = .09 and .34, respectively). Regarding referee bias, away teams received more yellow cards and fewer penalties than home teams in matches with spectators (p < .001; d = -.10), and away teams received fewer yellow cards than home teams in ghost matches (p > .05; d = .05). There was no statistically significant difference between home and away teams on number of red cards in either type of match (p > .05). Thus, our data reveal that home teams have an edge over away teams with and without spectators, but this advantage is reduced during ghost matches (without spectators). We also revealed weak evidence of referee bias in favor of home teams, but only for some variables and only when spectators were present.



#18 Clustering U-14 Portuguese regional team football players by lower limb strength, power, dynamic balance, speed and change of direction: understanding the field position factor

Reference: PeerJ. 2023 Jul 19;11:e15609. doi: 10.7717/peerj.15609. eCollection 2023.

Authors: Tatiana Sampaio, Daniel Marinho, José Eduardo Teixeira, João Oliveira, Jorge Morais

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Summary: The aim of this study was to cluster U-14 Portuguese regional team football players based on variables related to lower limb strength and power, dynamic balance, linear sprint, and change of direction. The sample consisted of 22 young male soccer players (13.83 ± 0.44 years). A set of variables related to lower limb strength and power, dynamic balance, linear sprint, and change of direction was measured. Overall, a non-significant field position was observed. The countermovement jump (p < 0.001, η2 = 0.73), squat jump (p < 0.001), and 30 m linear sprint (p = 0.001) were the main variables responsible for establishing the clusters. Cluster 1 was characterized by a high slalom, i.e., it took longer to complete the test (speed and change of direction) and a low composite score in the dynamic balance. Cluster 2 was characterized by high squat jump, countermovement jump, and reactive strength ratio (lower limb strength and power). Cluster 3 was characterized by low squat jump and countermovement jump (lower limb strength and power), and a high 30 m sprint, i.e., it took longer to complete the test (speed and change of direction). Based on the results of the territorial map, the clusters consisted of: (i) cluster 1: two forwards, one midfielder, and five defenders; (ii) cluster 2: three forwards, two midfielders, and two defenders, and; (iii) cluster 3: four midfielders and three defenders. Players from different field positions composed the three clusters. There was no cluster composed exclusively of players of the same field position. The development of individualized and specific enrichment training programs should consider a cluster analysis, as the positional effect can be overlooked.


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