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 Heart Rate Variability in Professional and Semiprofessional Soccer: A Scoping Review
Reference: Scand J Med Sci Sports. 2024 Jun;34(6):e14673. doi: 10.1111/sms.14673.
Authors: Mauro Mirto, Luca Filipas, Marco Altini, Roberto Codella, Andrea Meloni
Summary: In modern soccer, fitness and fatigue monitoring tools tend to be focused on noninvasive, time-efficient and player-friendly measures. Heart rate variability (HRV) has been suggested as an effective method for monitoring training response and readiness to perform. However, there is still a lack of consensus on HRV monitoring when it comes to soccer. Thus, this scoping review aims to map existing evidence on HRV in professional and semiprofessional soccer settings, and to identify knowledge gaps to inform future research directions. A search of databases (PubMed, Scopus, Web of Science, Google Scholar) according to the PRISMA-ScR statement was employed. Studies were screened for eligibility on inclusion criteria: (1) HRV was among the topics discussed in the article; (2) adult professional or semiprofessional soccer players were involved in the study; (3) both male and female participants; (4) no geographical area exclusion; (5) articles published in English; and (6) article full text available. The search of the selected databases revealed 8456 records. The titles and abstracts of all articles were retrieved for screening of eligibility, leaving 30 articles for further consideration. Following screening against set criteria, a total of 25 studies were included in this review, the sample size of which ranged from 6 to 124 participants. The participants in the included studies were professional and semiprofessional soccer players, interviewed clubs staff, and practitioners. Along with other monitoring strategies, morning vagally mediated HRV analysis via (ultra)short-term orthostatic measurements may be an efficient way to assess training adaptations and readiness to perform in professional and semiprofessional soccer players. Further research is required to make definitive recommendations.
2 Examining tactical sprint actions and distribution among playing positions attending to match status in soccer: Implications for specific training
Reference: PLoS One. 2024 Jun 10;19(6):e0301925. doi: 10.1371/journal.pone.0301925. eCollection 2024.
Authors: David Lobo-Triviño, Tomás García-Calvo, David Manzano-Rodríguez, Fabio Nevado, Marcos Chena, Juan Ángel Piñero-Madrona, Emilio Martín-Ardila, Javier Raya-González
Download link: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0301925
Summary: The study aimed to analyze the tactical sprint actions performed by Spanish professional soccer players, considering their playing positions and the match status at the time of each action. Thirty-two Spanish male professional soccer players from a LaLiga Spanish Second Division (LaLiga SmarthBank) team participated in this study. Actions above 85% of the players‘ maximum velocity during 42 official matches were collected by an optical tracking system ChyronHego® and were synchronized using Mediacoach software (LaLiga, Madrid, Spain). Then, actios were analyzed trough an observation instrument designed to assess the type of tactical action performed by players. Central defenders (CD) and wide defenders (WD) were mainly involved in recovery runs. Central midfielders (CM) also frequently performed recovery runs and pressing actions. Wide midfielders (WM) were often engaged in runs in behind/penetrate actions, while forwards (F) had a diverse range of sprint actions, including pressing, runs in behind/penetrate, and breaking into the box. It was observed that F performed fewer chase actions than expected. On the other hand, CD, WD, and CM engaged in a greater number of recovery run actions than expected. CD also performed more close down/interception actions than expected, while CM, WM, and F performed fewer close down/interception actions than expected. When their team was losing, WM performed more recovery run actions than expected. CM made more runs with the ball when their team was winning CD showed a higher frequency of breaks into the box when their team was winning. These findings provide valuable information regarding the tactical aspects of sprinting in soccer, facilitating the design of specific training tasks that not only address the physical demands associated with each playing position but also considering the tactical context in which sprints occur.
3 Comparing locomotor intensity indicators in soccer training and competition across contextual factors: a study of replaced coaches in a Portuguese professional 1st league team
Reference: Front Sports Act Living. 2024 May 24:6:1391784. doi: 10.3389/fspor.2024.1391784. eCollection 2024.
Authors: Honorato Sousa, Filipe Manuel Clemente, Hugo Sarmento, Élvio R Gouveia, Rabiu Muazu Musa
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11157433/pdf/fspor-06-1391784.pdf
Summary: This study aims to examine, for each head coach (HC) replaced, the association between training intensity and physical performances obtained in games. Furthermore, the study investigated how contextual factors influence locomotor and mechanical performance association. External load variables were collected using Global Positioning System (GPS) devices across the 4 weeks and 4 games before and after the replacement in a professional adult male soccer team. Six different HC records were analysed (48.8 ± 7.4 years of age; 11.2 ± 3.9 years as an HC) during a three-season span (2020/21-2022/2023). There were marked differences within player variability across the two coaching regimes. Game loads didn’t reflect training-related performance, with differences ranging from -71.4% to -9.9%. Players under the outgoing coaches have greater coverage of meters per minute. Meters per minute, distance covered over 18 km/h and high-speed running (all in training) are found to be significant variables influenced by contextual factors. Within-subject and time, training loads did not reflect game-related loads/performances, with starters showing higher deficits (ranging from -79.0 to -14.5). The study suggests that changes in soccer HC can affect players‘ training intensity and game performance, influenced by various contextual factors and not directly correlated. This type of information might be very suitable to improve training load periodization and programming. For further research avenues, could be the study of the variation of the psychological states of the players at the time of the dismissal and hiring of the HCs, associating them with the physiological performance at the same moments.
4 Predicting sports performance of elite female football players through smart wearable measurement platform
Reference: Prog Brain Res. 2024:286:1-31. doi: 10.1016/bs.pbr.2024.04.002. Epub 2024 May 11.
Authors: Chia-Kai Chang, Yu-Lun Chen, Chi-Hung Juan
Summary: Recent development of information technology and wearable devices has led to the analysis of multidimensional sports information and the enhancement of athletes‘ sports performance convenient and potentially more efficient. In this study, we present a novel data platform tailored for capturing athletes‘ cognitive, physiological, and body composition data. This platform incorporates diverse visualization modes, enabling athletes and coaches to access data seamlessly. Fourteen elite female football players (average age=20.6±1.3years; 3 forwards, 5 midfielders, 4 defenders, and 2 goalkeepers) were recruited from National Taiwan Normal University, Taiwan, as the primary observational group, and 12 female university students without regular sport/exercise habits (average age=21.6±1.3years) were recruited as control group. Through multidimensional data analysis, we identified significant differences in limb muscle mass and several cognitive function scores (e.g., reaction times of attention and working memory) between elite female football varsity team and general female university students. Furthermore, 1-month heart rate data obtained from wearable devices revealed a significant negative correlation between average heart rate median and cognitive function scores. Overall, this study demonstrates the potential of this platform as an efficient multidimensional data collection and analysis platform. Therefore, valuable insights between cognitive functions, physiological signals and body composition can be obtained via this multidimensional platform for facilitating sports performance.
5 Validity of a motor-cognitive dual-task agility test in elite youth football players
Reference: Eur J Sport Sci. 2024 Jun 14. doi: 10.1002/ejsc.12153. Online ahead of print.
Authors: David Friebe, Johanna Sieland, Hendrik Both, Florian Giesche, Christian Haser, Thorben Hülsdünker, Florian Pfab, Lutz Vogt, Winfried Banzer
Summary: Agility, as the ability to react rapidly to unforeseen events, is an essential component of football performance. However, existing agility diagnostics often do not reflect the complex motor-cognitive interaction required on the field. Therefore, this study evaluates the criterion and ecological validity of a newly developed motor-cognitive dual-task agility approach in elite youth football players and compare it to a traditional reactive agility test. Twenty-one male youth elite football players (age:17.4 ±0 .6; BMI:23.2 ± 1.8) performed two agility tests (reactive agility, reactive agility with integrated multiple-object-tracking (Dual-Task Agility)) on the SKILLCOURT system. Performance was correlated to motor (sprint, jump), cognitive (executive functions, attention, reaction speed) and football specific tests (Loughborough soccer passing test (LSPT)) as well as indirect game metrics (coaches‘ rating, playing time). Reactive agility performance showed moderate correlations to attention and choice reaction times (r = 0.48-0.63), as well as to the LSPT (r = 0.51). The dual-task agility test revealed moderate relationships with attention and reaction speed (r = 0.47-0.58), executive functions (r = 0.45-0.63), as well as the game metrics (r = 0.51-0.61). Finally, the dual-task agility test significantly differentiated players based on their coaches‘ rating and playing time using a median split (p < 0.05; d = 0.8-1.28). Motor-cognitive agility performance in elite youth football players seems to be primarily determined by cognitive functions. The integration of multiple object tracking into reactive agility testing seems to be an ecologically valid approach for performance diagnostics in youth football.
6 Economic impact of muscle injury rate and hamstring strain injuries in professional football clubs. Evidence from LaLiga
Reference: PLoS One. 2024 Jun 13;19(6):e0301498. doi: 10.1371/journal.pone.0301498. eCollection 2024.
Authors: Laura Nieto Torrejón, Antonio Martínez-Serrano, José M Villalón, Pedro E Alcaraz
Download link: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0301498
Summary: The aims of this study were: 1) to describe the total muscular injuries, and specifically HSIs, and their corresponding missed matches; 2) to analyse their economic impact; and 3) to estimate the loss of incomes due to TV rights, in first division clubs from LaLigaTM depending on the expected and actual ranking position during the 2018/2019 season. To do that, a cross-sectional study for season 18/19 and for all players of the 20 Spanish professional football clubs was performed. The economic impact of injuries was estimated considering the missed matches and salary cost of all players and the audio-visual income loss was estimated considering the Spanish Royal Decree of Law (RDL 5/2015). The high number of muscular (270) and hamstring injuries (57) implies a high cost for professional first division football clubs, specifically € 365,811 per month for the former and € 47,388 per month for the latter. In addition, reaching a worse than expected position in LaLigaTM ranking involved a loss of 45,2 million € in TV rights incomes. The high cost of muscle injuries in first division teams justifies the need for multidisciplinary teams that are capable of reducing the number of injuries as well as recovery times.
7 Effect of peak intensity periods on temporary fatigue and recovery kinetics in professional male football
Reference: J Sports Sci. 2024 Jun 12:1-7. doi: 10.1080/02640414.2024.2364135. Online ahead of print.
Authors: E N Leifsson, P Krustrup, M Mohr, M B Randers
Summary: We analysed peak 1-, 2- and 5-min periods and the associated 5-min recovery period in matches from three consecutive seasons in the Danish Superliga. A semi-automatic multicamera system was used to collect high-speed running distance (≥5.5 m/s; HSRD), sprint distance (≥7.0 m/s; SpD) and distance covered during intense acceleration (≥3 m/s2; AccD). Analysis included 479 players and 6042 to 9671 match observations using rolling average. Distances covered per minute during the peak periods were significantly higher than match averages: HSRD (207-772%), SpD (447-1793%), and AccD (383-1096%). Distances covered per min were lower during 1-min recovery periods than match average for HSRD following peak 1-, 2- and 5-min period (29%, 6%, 3%, 2%, 2%; 35%, 11%, 0%, 2%, 3%; and 45%, 29%, 13%, 8%, 4%; p < 0.05, respectively), and for SpD (20%, 3%, 7%, 3% (4% higher in the 5th min); 24%, 12%, 3%, 0%, 7%; and 39%, 29%, 18%, 17%, 12%; p < 0.05, respectively). Opposite, AccD increased in the following 1-min recovery periods following peak 1-, 2- and 5-min periods (68%, 89%, 94%, 88%, 90%; 47%, 86%, 93%, 90%, 88%; 23%, 56%, 76%, 85%, 87%; p < 0.05) compared to match averages. Intensity was higher during shorter periods, whereas performance decrements were largest after longer peak periods for HSRD and SpD, whereas no decrement was observed in AccD.
8 Heading in football: a systematic review of descriptors, definitions, and reporting methods used in heading incidence studies
Reference: Sci Med Footb. 2024 Jun 10:1-18. doi: 10.1080/24733938.2024.2362191. Online ahead of print.
Authors: Kerry Peek, Andrew Ross, Thor Einar Andersen, Tim Meyer, Sara Dahlen, Julia Georgieva, Paula R Williamson, Mike Clarke, Andreas Serner
Summary: The primary objective of this systematic review was to describe the number and type of heading descriptors used in all published studies which report on heading incidence in football. The secondary objective was to detail the data collection and reporting methods used in the included studies to present heading incidence data. Eligible studies were identified through searches of five electronic databases: Ovid MEDLINE, CINAHL, EMBASE, SPORTDiscus, and Web of Science, using a combination of free-text keywords (inception to 12th September 2023). Manual searching of reference lists and retrieved systematic reviews was also performed. A descriptive overview and synthesis of the results is presented. From 1620 potentially eligible studies, 71 studies were included, with the following key findings: 1) only 61% of studies defined a header with even fewer (23%) providing an operational definition of a header within the methods; 2) important study and player demographic data including year and country were often not reported; 3) reported heading descriptors and their coding options varied greatly; 4) visual identification of headers was essential when inertial measurement units were used to collect heading incidence data; and 5) there was a lack of standardisation in the reporting methods used in heading incidence studies making comparison between studies challenging. To address these findings, the development of a standardised, internationally supported, operational definition of a header and related heading descriptors should be prioritised. Further recommendations include the development of minimum reporting criteria for heading incidence research.
9 Survey of sun protection behaviors and barriers among spectators at an outdoor football game
Reference: Arch Dermatol Res. 2024 Jun 8;316(7):370. doi: 10.1007/s00403-024-03067-0.
Authors: Ryan Murphy, Camille Moeckel, Jill Stachowski, Amy Longenecker, Elizabeth M Billingsley, Charlene Lam
Download link: https://link.springer.com/content/pdf/10.1007/s00403-024-03067-0.pdf
10 Fat-free mass predictive equation using multifrequency bioelectrical impedance data in adolescent soccer athletes: development and cross-validation
Reference: Nutrition. 2024 May 11:125:112484. doi: 10.1016/j.nut.2024.112484. Online ahead of print.
Authors: Marcus Vinicius de Oliveira Cattem, Gabriela Morgado de Oliveira Coelho, Josely Correa Koury
Summary: This study aimed to develop and cross-validate a fat-free mass (FFM) predictive equation using multifrequency bioelectrical impedance analysis (BIA) data in adolescent soccer athletes. Male adolescent soccer athletes (n = 149; 13-19 y old) were randomly sorted using Excel and independently selected for development group (n = 100) or cross-validation group (n = 49). The FFM reference values were determined using dual-energy X-ray absorptiometry. Single-frequency BIA was used to plot tolerance ellipses. Multifrequency-BIA raw data were used as independent variables in regression models. Student’s independent t-test was used to compare development and cross-validation groups. Stepwise multiple regression was used to develop the FFM predictive equation. Bland-Altman plots, Lin’s concordance correlation coefficient, according to McBride criteria, precision, accuracy, and standard error of estimate (SEE) were calculated to evaluate the concordance and reliability of estimates. Bioelectrical impedance vector analysis was plotted to assess hydration status. No differences (P > 0.05) were observed between development and validation groups in chronological age, anthropometric data, bioelectrical impedance data, and FFM values obtained using dual-energy X-ray absorptiometry. Bioelectrical impedance vector analysis tolerance showed that all participants presented adequate hydration status compared to the reference population. The new FFM predictive equation developed and validated: FFM (kg) = -7.064 + 0.592 × chronological age (y) + 0.554 × weight (kg) + 0.365 × height²/resistance (cm²/Ω), presented R² = 0.95; SEE = 1.76 kg; concordance correlation coefficient = 0.95, accuracy = 0.98, and strength of concordance = 0.99. The present study developed and cross-validated an FFM predictive equation based on multifrequency bioelectrical data providing substantial FFM accuracy for male adolescent soccer athletes.
11 The Relationship Between Individually Assessed High-Intensity Accelerations, High-Intensity Decelerations, Sprints, and Technical Performances During Soccer Matches: A Full Season Analysis
Reference: Res Q Exerc Sport. 2024 Jun 21:1-8. doi: 10.1080/02701367.2024.2353713. Online ahead of print.
Authors: Hugo Silva, Fábio Yuzo Nakamura, Gibson Praça, João Ribeiro, Rui Marcelino
Summary: This longitudinal study analyzed the relationship between players‘ physical (sprint distances, number of high-intensity accelerations and decelerations assessed with individual and relative thresholds) and technical (retrieved from SofaScore platform) performances during competition. Twenty elite players were monitored across a full season. Physical performances were monitored with GNSS devices, retrieving time (s), velocity (km.h-1) and distance (m). Sprint distances were calculated as > 80% of the match peak speed registered across the season. High-intensity accelerations and decelerations were calculated as >75% of the peak values registered across the season. Pearson (r) correlations (with 95% confidence intervals) were calculated to assess the relationship among different physical performance variables and between the physical and technical performance variables. Sprint distances correlated with the number of ball touches (r = -0.36 [-0.49, -0.23], p < .001), accurate passes (r = -0.45 [-0.56, -0.32], p < .001), and dribble attempts (r = 0.30 [0.16, 0.43], p < .001). If players touched the ball more frequently and pass the ball more accurately, they covered shorter sprint distances. However, if players attempted more dribbles, they covered longer sprint distances. Practitioners can develop tactical strategies considering the relationship between sprint distances and technical variables such as ball touches, accurate passes, and dribble attempts.
12 Things to keep in mind when selecting physical assessments in youth soccer: Correlations between test performances, interlimb asymmetries, and effects of maturation
Reference: PLoS ONE, 19(6): e0305570. https://doi.org/10.1371/journal.
pone.0305570
Authors: Francisco Javier Robles-Palazón, John J McMahon, Francisco Ayala, Paul Comfort
Download link: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0305570
Summary: A range of field-based tests have been proposed for inclusion in physical performance assessment batteries. However, there are obvious time and human resources constraints in applied settings. The knowledge of potential relationships between tests on performance, asymmetries, as well as maturation-induced changes, may help select the most informative and least time-consuming testing battery. The purposes of this study were: (1) to determine correlations in performance between different field-based tests, in interlimb asymmetry between those unilateral tests, and between asymmetry scores and test performances, and (2) to determine the influence of players‘ maturity status on test performances and asymmetries. A total of 309 male youth soccer players completed a nine-test battery including y-balance test, drop vertical jump, countermovement jump, single leg countermovement jump, standing long jump, single leg hop for distance, Illinois agility test, 10 m sprint, and 20 m sprint. The results revealed moderate-to-very large relationships between jump, sprint, and agility performances (r = 0.43-0.94), but weak-to-moderate correlations between these tests and balance scores (r ≤ 0.38). No relevant relationship (r ≤ 0.32) for asymmetries detected through different unilateral tests was found, nor between asymmetries and performance scores (r < 0.29). While maturity status clearly influenced players‘ performance, a limited impact on asymmetries was evident. Despite the mentioned relationships, the low shared variance between tests indicates that they should not be used interchangeably, and coaches should select those with the greatest specificity for the sport. Asymmetries do not influence performance, but their prevalence and unchanging nature with maturation can be seen as an opportunity for the identification of highly asymmetrical players and the application of interventions to improve the weaker limb, irrespective of the athlete’s stage of development. To this end, the single leg countermovement jump might be viewed as an appropriate test in male youth soccer.
13 Mental rotation abilities of gymnasts and soccer players: a comparison of egocentric and object-based transformations. An exploratory and preliminary study
Reference: Front Psychol. 2024 Jun 5:15:1355381. doi: 10.3389/fpsyg.2024.1355381. eCollection 2024.
Authors: Thomas Jürgen Klotzbier, Nadja Schott
Summary: The experience obtained from motor expertise may contribute to and enhance the development of particular visuo-spatial abilities. This exploratory and preliminary study compares the response times of a mental rotation task with egocentric and object-based transformation instructions between soccer players of varying performance levels and gymnasts. Fifty-six male participants were grouped based on their sports experience. Soccer-specific novices (SS-N: n = 19; age = 15.9 ± 0.87), soccer-specific experts (SS-E: n = 17; age = 16.4 ± 0.70), gymnastic-specific experts (GS-E: n = 10; age = 16.6 ± 1.71), and gymnastic-specific novices (GS-N: n = 10; age = 16.0 ± 1.63) were recruited to perform a perceptual task (recognition of soccer-specific poses) and mental rotation tasks with different stimuli (soccer-specific poses, cubes, line-drawings of hands, letters). During the perceptual task with instructions on egocentric transformation and soccer-specific poses, we observed that gymnasts had longer response times than soccer players. Our findings also suggest that experts correctly identified most of the poses in terms of accuracy. In the mental rotation task with object-based transformation, gymnasts processed all stimuli, even the soccer-specific poses, more accurately than both soccer groups.
Conclusion: Our results suggest that gymnasts‘ motor expertise plays a role in their performance on mental rotation tasks involving both egocentric and object-based transformations, regardless of the stimuli presented.
14 Epidemiology of Non-Contact Muscle Injuries in the Italian Male Elite Under-19 Football (Soccer) Championship
Reference: Sports Med Open. 2024 Jun 21;10(1):75. doi: 10.1186/s40798-024-00738-0.
Authors: Massimo Magistrali, Luca Stefanini, Michele Abate, Giulio Biancalana, Andrea Stegagno, et al.
Summary: While extensive research exists on muscle injuries among adult football players, a notable gap persists in studies concerning younger footballers. The aim of the current study is to provide epidemiological data on the characteristics of time-loss muscle injuries in young football players participating in the Italian Under-19 male elite Championship („Primavera 1“). Conducted as a multicentre, prospective, observational cohort study, this research gathered injury data from the 2022-23 season across 14 of the 18 Clubs in the first Italian Under-19 championship. The cohort comprised 391 players with a mean age (± standard deviation) of 18.0 ± 0.4 years. A total of 479 injuries were reported, resulting in 14,231 days of activity lost. Of these, muscle injuries were 209 (44%), accounting for 4,519 (32%) days lost. Overall muscle injuries incidence was 1.82/1000 hours, with a mean injury burden of 39.4 days lost/1000 hours. Almost all muscle injuries (206 out of 209: 98.5%) occurred in hamstrings, quadriceps, adductors, calf and iliopsoas. Hamstrings injuries were the most burdensome (18.8 days lost/1000 hours) accounting for nearly half of all days lost due to muscle injuries. Incidence and burden of adductors injuries (0.25 injuries and 4.1 days lost/1000 hours, respectively) were found to be comparable to calf injuries (0.24 injuries and 4.7 days lost/1000 hours, respectively). Iliopsoas injuries accounted for a noteworthy portion of the total, with an injury incidence of 0.16/1000 hours and a burden of 3.3 days lost/1000 hours. Injuries with myo-tendinous or myo-aponeurotic involvement demonstrated delayed return-to-football compared to those without such involvement (35.6 vs. 18.5 days, p < 0.0001). The study highlighted a peculiar distribution of non-contact muscle injuries among elite young football players. While hamstring injuries were confirmed as the most burdensome, incidence and burden of adductors and calf injuries were found to be similar. A significant incidence and burden of iliopsoas injuries were observed. These findings suggest potential implementations for targeted injury prevention strategies in the Italian male elite Under-19 football Championship.
15 Effect of maturity status on force-velocity relationships in a ballistic lower limb test in high-level soccer players
Reference: J Sports Sci. 2024 Jun 20:1-11. doi: 10.1080/02640414.2024.2366743. Online ahead of print.
Authors: Paul Galantine, Denis Bertin, Pascale Duché, Arnaud Hays
Summary: This study aimed to investigate the effect of maturity status on force-velocity relationships in a ballistic lower limb (BLL) test in high-level soccer adolescents and young adults. The population was 61 adolescents (13.0-17.9 years) and 23 young adults (18.0-26.2 years). Subjects completed the BLL test on a ballistic ergometer equipped with two force plates and a linear encoder. Following Samozino’s method, maximal power output (Pmax), force (F0) and velocity (v0) were determined. An allometric model was applied to Pmax and F0 with body mass (BM) and fat-free mass (FFM). Significant effects of maturity status were found for absolute Pmax, F0, relative Pmax to BM and FFM, relative F0 to FFM and F0 allometrically scaled to BM and FFM (p = 0.02 to p < 0.001; η𝜂 = 0.10 to η𝜂 = 0.49). There was no significant effect for Pmax allometrically scaled to BM and FFM, F0 relative to BM and v0. Body dimensions explain group differences in Pmax whereas for F0, qualitative factors explain the differences between the groups. As maturity status and body dimensions influence Pmax, these factors should be considered when assessing explosive short efforts. This could help to better identify potential athletic talent and adapt training content.
16 Locomotor and Physiological Demands of Small-Sided Soccer Games in Wildcard and Regular Players: Effects of Goalkeepers and Type of Wildcard
Reference: Sports Health. 2024 Jun 20:19417381241257175. doi: 10.1177/19417381241257175. Online ahead of print.
Authors: Alejandro Rodríguez-Fernández, Filipe M Clemente, Rodrigo Ramírez-Campillo, Javier Sánchez-Sánchez
Summary: Small-sided games (SSGs) are frequent training drills in soccer. This study investigated whether type of game (ie, with/without goalkeepers) and wildcard ( without vs internal vs external wildcard) impact the physiological (heartrate [HR]) and locomotor (total distance [TD] covered) demands in regular and wildcard players and to evaluate between-player and within-player variability. The hypothesis was that demands are influenced by wildcard and game type, with higher demand (distance covered at high intensities and sprint speed) in regular players and with higher variability in SSG with wildcard players. Twenty-four soccer players completed 6 SSG as 3 versus 3 without (NG) or with (GK) goalkeepers, and with internal (NG+IW and GK+IW) and external (NG+EW and GK+EW) wildcard. Average HR (HRavg), rate of perceived exertion, and locomotor demands (TD, medium [MID = 7.0-13.9 km h-1], high [HID = 14.0-20.9 km h-1] and sprint [SPD >21.0 km h-1] distance and peak speed [PS]) were registered. The inclusion of GK and internal wildcard led to decreased HRavg and TD in regular players. Wildcard players positioned internally exhibited higher TD, PS, and lower HRavg than externally positioned wildcards. Regular players demonstrated higher TD, PS, MID, HID, HRavg and time spent in Z3 (>90% HRmax) compared with wildcard players in SSG played with external wildcard. Regular and wildcard players displayed great between- and within-player variability in high-intensity metrics. Specific game type and wildcard inclusion impact the physiological and locomotor demands in SSG, with variations observed between regular and wildcard players. This study provides comprehensive information on the physiological and locomotor demands of SSG depending on the inclusion and position of goalkeepers and wildcards, which can be useful for strength and conditioning coaches when designing specific training tasks, individualizing training load and applying return-to-play programs.
17 Defining Worst-Case-Scenario Thresholds in Soccer: Intensity Versus Volume
Reference: Int J Sports Physiol Perform. 2024 Jun 19:1-5. doi: 10.1123/ijspp.2024-0038. Online ahead of print.
Authors: Mauro Mandorino, Mathieu Lacome
Summary: This study aimed to enhance the understanding of soccer match peak demands by describing worst-case scenario (WCS) and time spent above 80% and 90% of the WCS for total distance (TD) and high-speed running (HSR). The investigation considered playing level (first team vs under-19 [U19] team) and playing position (center backs, fullbacks, midfielders, and forwards) to assess how WCS and the time spent above specific thresholds vary across different populations. Data from 31 players in a professional Italian soccer club were collected during the 2022-23 season. Microtechnology devices tracked physical activity during matches. Players were categorized by position, and WCS was determined using rolling averages over a 1-minute period. Time spent above 80% and 90% of WCS for TD and HSR was calculated. The U19 team exhibited higher HSR WCS compared with the first team (∼63 m·min-1 vs ∼56 m·min-1). Midfielders recorded the highest TD WCS (∼208 m·min-1), and forwards exhibited the highest HSR WCS (∼70 m·min-1). The first team spent significantly more time above 80% (∼6 min) and 90% (∼1 min) of TD WCS. Midfielders spent significantly more time above the 80% (∼7 min) of TD WCS, while forwards above the 80% (∼2 min) of HSR WCS. The study emphasizes that WCS used alone may not sufficiently capture real match intensity. Considering the time spent above specific thresholds provides additional insights (ie, between-levels differences and position). Practitioners should consider both WCS and time spent above thresholds for individualized training prescriptions, reflecting differences in playing roles.
18 Leukocyte-Rich Platelet-Rich Plasma Injection in an Acute-on-Chronic Rectus Femoris Injury of a Professional Soccer Player: A Case Report
Reference: J ISAKOS. 2024 Jun 17:S2059-7754(24)00122-6. doi: 10.1016/j.jisako.2024.06.005. Online ahead of print.
Authors: Patricia Nuñez DE Aysa, Jonas Grani Garðarsson, Ayyoub Al-Dolaymi, Marcelo Bordalo-Rodrigues, Markus Laupheimer, Theodorakys Marín Fermín
Download link: https://www.jisakos.com/action/showPdf?pii=S2059-7754%2824%2900122-6
Summary: This is the case of an 18-year-old male professional soccer player, an attacking midfielder, who presented acute onset pain in his right thigh during a training match but continued playing and training until the end of the session. Two weeks after the initial symptoms, the athlete’s pain increased after kicking the ball and stopping training. He came for consultation a week later with tenderness in his right thigh and impaired gait. A 3 cm gap in his right mid quadriceps muscle and tenderness during resisted knee extension and leg raises with no hip or knee range of motion limitation were observed on physical examination. He was scheduled for magnetic resonance imaging (MRI) after the consultation, revealing an acute-on-chronic type 2A lateral muscle tear of the distal rectus femoris. A 2 ml seroma aspiration was performed five weeks after the initial injury with a subsequent intra-lesional 1 ml liquid leukocyte-rich platelet-rich plasma (LR-PRP) injection using intermittent ultrasound guidance within 5 minutes after preparation. The LR-PRP preparation was classified as 3 14 – 1 3 – 0 0 according to the Universal Coding System (UCS) by Kon et al. Nine physiotherapy sessions, including an initial assessment, were conducted over five weeks. The rehabilitation started with pulley exercises with hip flexion, tension arch, leg extension, and squatting with supporting exercises for core and hip strength, with a gradual increase in loading. As the player’s symptoms improved, he started doing eccentric exercises such as the reverse Nordics and leg extension. He also followed a running program, gradually increasing speed to full sprint without pain or irritation. The return to sports clearance consultation was conducted seven weeks after the injury, previously confirming satisfactory healing on MRI. The patient was cleared after passing the Rehabilitation Department battery tests and physical examination. The patient was asymptomatic and had no complaints despite his right quadriceps gap, returning to competition nine weeks after injury. After a one-year follow-up, the patient remains playing at a competitive level, asymptomatic, with no reported reinjury. Adequate reporting of rehabilitation programs and PRP injection characterization is crucial for future research quality improvement and reproducibility.
19 Validation of Step Detection and Distance Calculation Algorithms for Soccer Performance Monitoring
Reference: Sensors (Basel). 2024 May 23;24(11):3343. doi: 10.3390/s24113343.
Authors: Gabriele Santicchi, Susanna Stillavato, Marco Deriu, Aldo Comi, Pietro Cerveri, Fabio Esposito, Matteo Zago
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11174549/pdf/sensors-24-03343.pdf
Summary: This study focused on developing and evaluating a gyroscope-based step counter algorithm using inertial measurement unit (IMU) readings for precise athletic performance monitoring in soccer. The research aimed to provide reliable step detection and distance estimation tailored to soccer-specific movements, including various running speeds and directional changes. Real-time algorithms utilizing shank angular data from gyroscopes were created. Experiments were conducted on a specially designed soccer-specific testing circuit performed by 15 athletes, simulating a range of locomotion activities such as walking, jogging, and high-intensity actions. The algorithm outcome was compared with manually tagged data from a high-quality video camera-based system for validation, by assessing the agreement between the paired values using limits of agreement, concordance correlation coefficient, and further metrics. Results returned a step detection accuracy of 95.8% and a distance estimation Root Mean Square Error (RMSE) of 17.6 m over about 202 m of track. A sub-sample (N = 6) also wore two pairs of devices concurrently to evaluate inter-unit reliability. The performance analysis suggested that the algorithm was effective and reliable in tracking diverse soccer-specific movements. The proposed algorithm offered a robust and efficient solution for tracking step count and distance covered in soccer, particularly beneficial in indoor environments where global navigation satellite systems are not feasible. This advancement in sports technology widens the spectrum of tools for coaches and athletes in monitoring soccer performance.
20 Goldfit Soccer: A Multidimensional Model for Talent Identification of Young Soccer Players
Reference: Res Q Exerc Sport. 2024 Jun 17:1-15. doi: 10.1080/02701367.2024.2347983. Online ahead of print.
Authors: Francisco Zacaron Werneck, Emerson Filipino Coelho, Marcelo de Oliveira Matta, Rodrigo César Pedrosa Silva, António José Barata Figueiredo
Summary: Studies have provided empirical evidence on the prognostic relevance of test batteries and the „coach’s eye“ for talent identification. The aims were 1) to compare objective and subjective assessments as well as a combined soccer-specific potential index between future selected and non-selected players and 2) to evaluate the prognostic validity of a multidimensional model as a tool for talent identification in soccer. The sample was composed by 132 male players (14,5 ± 1,4 years; regional competitive level) from U13 to U17 age groups of a Brazilian soccer talent development program. Athletes completed a multidimensional test battery and were subjectively rated by their coaches for sporting potential. Players‘ success was evaluated five years later and was operationalized by achieving under-20 category of the Brazilian Championship or adult professional level (success rate, 15.9%). Confirming univariate prognostic validity, future selected outperformed non-selected players regarding 20-m sprint (p = .009), agility (p = .04), countermovement jump (p = .04), sit-and-reach (p = .001), Yo-Yo IR1 (p = .001), dribbling (p < .001), perceived competence (p = .007), peaking under pressure (p = .01), confidence/motivation (p = .03), coping skills (p = .03), intangibles (p < .001) and player potential (p < .001). A combined index (objective tests, athlete’s assessments and coach’s eye) named Gold Score Soccer (GSS) showed high prognostic validity (p < .001). A binary logistic regression estimated the probability of success (yes/not) with GSS, ambidextrous and predicted age at peak height velocity as predictors. This multidimensional model named GoldFit Soccer showed high prognostic validity (sensitivity = 85.7%; specificity = 83.8%; accuracy = 84.1%; area under the ROC curve = .93 [.87-.98]). Thus, GoldFit Soccer is a valid multidimensional scientific model for talent identification in soccer.