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 Validity and Reliability of a New Wearable Chest Strap to Estimate Respiratory Frequency in Elite Soccer Athletes
Reference: Sports (Basel). 2024 Oct 12;12(10):277. doi: 10.3390/sports12100277.
Authors: Adriano Di Paco, Diego A Bonilla, Rocco Perrotta, Raffaele Canonico, Erika Cione, Roberto Cannataro
Download link: https://www.mdpi.com/2075-4663/12/10/277
Summary: Assessing respiratory frequency (fR) is practical in monitoring training progress in competitive athletes, especially during exercise. This study aimed to validate a new wearable chest strap (wCS) to estimate fR against ergospirometry as a criterion device in soccer players. A total of 26 elite professional soccer players (mean [standard deviation]: 23.6 [4.8] years; 180.6 [5.7] cm; 77.2 [5.4] kg) from three Italian Serie A League teams participated in this cross-sectional study. The sample included attackers, midfielders, and defenders. fR was assessed during a maximal cardiopulmonary exercise test (CPET) on a treadmill using (i) a breath-by-breath gas exchange analyzer (Vyntus® CPX, Vyaire Medical) and (ii) a novel wCS with sensors designed to assess breath frequency following chest expansions. Pearson’s correlation coefficient (r), adjusted coefficient of determination (aR2), Bland-Altman plot analysis, and Lin’s concordance correlation coefficient (ρc) were used for comparative analysis (correlation and concordance) among the methods. The repeated measures correlation coefficient (rrm) was used to assess the strength of the linear association between the methods. The intraclass correlation coefficient (ICC) and the Finn coefficient (rF) were used for inter-rater reliability. All statistical analyses were performed within the R statistical computing environment, with 95% confidence intervals (95% CIs) reported and statistical significance set at p < 0.05. A total of 16529 comparisons were performed after collecting the CPET data. The robust time series analysis with Hodges-Lehmann estimation showed no significant differences between both methods (p > 0.05). Correlation among devices was statistically significant and very large (r [95% CI]: 0.970 [0.970, 0.971], p < 0.01; aR2 [95% CI]: 0.942 [0.942, 0.943], p < 0.01) with strong evidence supporting consistency of the new wCS (BF10 > 100). In addition, a high concordance was found (ρc [95% CI]: 0.970 [0.969, 0.971], bias correction factor: 0.999). VyntusTM CPX, as a standard criterion, showed moderate agreement with wCS after Bland-Altman analysis (bias [95% lower to the upper limit of agreement]; % agree: 0.170 [-4.582 to 4.923] breaths·min-1; 69.9%). A strong association between measurements (rrm [95% CI]: 0.960 [0.959, 0.961]), a high absolute agreement between methods (ICC [95% CI]: 0.970 [0.970, 0.971]), and high inter-rater reliability (rF: 0.947) were found. With an RMSE = 2.42 breaths·min-1, the new wCS seems to be an valid and reliable in-field method to evaluate fR compared to a breath-by-breath gas exchange analyzer. Notwithstanding, caution is advised if methods are used interchangeably while further external validation occurs.
2 Impact of offensive team variables on goal scoring in the first division of the spanish soccer league: a comprehensive 10-year study
Reference: Sci Rep. 2024 Oct 24;14(1):25231. doi: 10.1038/s41598-024-77199-8.
Authors: Pablo Prieto-González, Víctor Martín, Martin Pacholek, Alejandro Sal-de-Rellán, Rui Marcelino
Download link: https://www.nature.com/articles/s41598-024-77199-8.pdf
Summary: This study assessed the impact of team offensive variables on goals scored in Spain’s first-division soccer league from 2012-2013 to 2021-2022. A nomothetic multidimensional study was conducted, following the STROBE checklist. From 115 team variables available in the INSTAT database, 57 offensive metrics were selected. The selection was performed independently by five researchers to ensure comprehensive inclusion of relevant metrics. The data included 38 league matches each season, involving 30 teams. The study identified key offensive performance metrics strongly correlated with goals scored. These include shots on target (r = 0.898), chances created (r = 0.871), penalty box entries (r = 0.852), positional attacks with shots (r = 0.818), total shots (r = 0.807), central attacks with shots (r = 0.804), accurate passes (r = 0.760), and efficiency in positional attacks (r = 0.755). The findings underscore the importance of specific offensive metrics in enhancing goal-scoring capabilities. Coaches can improve their team’s offensive performance by focusing on passing accuracy, dribbling, and maximizing scoring chances. Successful teams consistently convert attacks into shots on goal through various situations, including central attacks, flanks, counterattacks, corners, and set pieces. Tactical adjustments based on these insights can optimize offensive effectiveness.
3 Effects of 2 Combined Training Protocols on the Aerobic and Anaerobic Fitness, Technical Skills, and Psychophysiological Responses in Young Soccer Players
Reference: J Strength Cond Res. 2024 Oct 24. doi: 10.1519/JSC.0000000000004955. Online ahead of print.
Authors: Bulent Kilit, Paweł Chmura, Ersan Arslan, Yusuf Soylu, Łukasz Radziminski
Summary: The study compared the effects of combining small-sided soccer games (SSGs) with high-intensity interval training (HIIT) and repeated sprint training (RST) on aerobic and anaerobic fitness, technical skills, and psychophysiological responses in young soccer players. Thirty-two male, adolescent, soccer players (aged 13.5 ± 0.3 years) were randomly divided into either the SSGs + HIIT group ( n = 16) or the SSGs + RST group ( n = 16) for combined training 3 times per week for 6 weeks. The players in the SSGs + HIIT group performed 12-18 minutes of runs at intensities (90-95%), whereas the players in the SSGs + RST group consisted of 3-4 sets of 5-7 times 15-m shuttle sprints (all-out efforts). Both training groups played 4 bouts of 2-a-side or 4-a-side SSGs with various game formats at 2-day intervals. Psychophysiological responses were determined during and after all training sessions. Before and after training interventions, the following physical performance tests were used: 5- to 30-m sprint time, countermovement jump, triple-hop distance, zigzag agility with the ball and without the ball, repeated sprint ability (RSA), 30-15 Intermittent Fitness Test, 3 corner run test, speed dribbling ability (SDA), Yo-Yo Intermittent Recovery Test Level 1, and Y-balance test. Our main findings were that the SSGs + RST group demonstrated greater improvement in 5-m sprint time, SDA time, and RSA in the meantime compared with the SSGs + HIIT ( p ≤ 0.05, d values ranging from 1.50 to 2.25). Moreover, the SSGs + RST group showed greater improvement in agility test responses ( p ≤ 0.05, d values ranging from 2.13 to 2.34) than the SSGs + HIIT group. However, the SSGs + HIIT induced higher perceived exertion, mental effort, and lower greater physical enjoyment meaningfully compared with the SSGs + RST ( p ≤ 0.05, d values ranging from 6.04 to 6.67). In conclusion, these results demonstrate that the SSGs + RST is an effective training program to improve young soccer players‘ speed and agility-based performance responses.
4 Environmental Heat Stress Detrimentally Affects Match Running Performance of Elite Soccer Teams Competing in the UEFA Champions League
Reference: J Strength Cond Res. 2024 Oct 24. doi: 10.1519/JSC.0000000000004977. Online ahead of print.
Authors: Toni Modric, Filipe Manuel Clemente, Sime Versic, Paweł Chmura, Marcin Andrzejewski, Jakub Kryściak, Damir Sekulic
Summary: This study aimed to examine the effect of environmental heat stress (EHS), defined by wet-bulb globe temperature (WBGT), on match running performance (MRP) while controlling for match-related contextual factors. For this purpose, 2 approaches were implemented: (a) the MRP in heat stress nonrisking environment (NoEHS) (WBGT <22° C) and heat stress risking environment (EHSrisk) (WBGT ≥22° C) were compared and (b) changes in MRP according to the 1° C increase in WBGT were evaluated. Data on MRP were collected using an optical tracking system from all teams ( n = 32) in all UEFA Champions League matches ( n = 125) during the 2022-23 season. Metrics included total distance (TD), low-intensity (LIR), moderate-intensity (MIR), and high-intensity running (HIR) distances. Results indicated that less TD (108.84 vs. 110.71 km; Cohen’s d [ d ] = 0.53), MIR (15.91 vs. 17.09 km; d = 0.85), and HIR (8.75 vs. 9.23 km; d = 0.46) were covered in matches played in EHSrisk compared with the NoEHS. Further investigation indicated that for every 1° C increase in WBGT, TD averagely decreased by 0.16 km ( d = -0.48), MIR by 0.13 km ( d = -1.09), and HIR by 0.06 km ( d = -0.69). These findings demonstrated decreased overall and intensive workload during the matches in EHSrisk, suggesting the detrimental effect of EHS on match volume and intensity in elite soccer. When EHS risk is anticipated, consideration of playing and recovery strategies should be implemented by coaches to achieve tactical goals while minimizing physical strain during a match.
5 Quadriceps Muscle Geometry and Strength Throughout Maturation in National-Level Male Soccer Players: A Cross-Sectional Study
Reference: Open Access J Sports Med. 2024 Oct 19:15:159-170. doi: 10.2147/OAJSM.S482796. eCollection 2024.
Authors: Paul Ritsche, Ralf Roth, Thomas Bernhard, Lukas Nebiker, Eric Lichtenstein, Martino Franchi, Jörg Spörri, Oliver Faude
Download link: https://www.dovepress.com/article/download/96538
Summary: Adolescent soccer players experience distinct physiological changes due to chronological and biological maturation, impacting their soccer performance. Here, we explored age-related variations and associations between quadriceps geometry and strength in male national-level adolescent soccer players. We used ultrasonography to examine the regional architecture and morphology of the rectus femoris (RF) and vastus lateralis (VL) muscles, and we assessed knee extension strength by isometric and isokinetic dynamometry. Players were categorized into four age groups: under (U) 15 (n=18, age=13.7±0.5 years), U16 (n=15, age=14.7±0.5), U17 (n=19, age=15.7±0.5), U18 (n=18, age=16.7±0.5) and U21 (n=25, age=18.5±0.5). The absolute and relative strengths were higher in the U16 compared to U15 by 12-15% and 6-8%, 11-12% and 6-7% in the U17 compared to U16, 5-7% and -1-2% in the U18 compared to U17 and 0-15% and -1-11% in the U21 compared to U18 age groups, respectively. VL architecture did not change relevantly between the age groups. The muscle anatomical cross-sectional area (ACSA) of the VL and RF differed non-uniformly and muscle region-specific by 10-36%, with highest values in the U21 age group. Moderate correlations between the VL architecture and knee extension strength in both legs were observed only in the U16 age group. The quadriceps ACSA showed age-specific correlations with knee extension strength. Our findings highlight non-uniform differences in quadriceps muscle morphology and absolute and relative strength among male national-level adolescent soccer players in different age groups. The correlations observed between muscle morphology or architecture and strength were muscle, muscle region, leg and age dependent.
6 The Physician and SportsmedicineThe 10-year decreasing trend of youth soccer head injuries and concussions presenting to U.S. Emergency departments
Reference: Phys Sportsmed. 2024 Oct 24. doi: 10.1080/00913847.2024.2421154. Online ahead of print.
Authors: Alex G Chun, Eli M Snyder, Kyle K Obana, Beth G Ashinsky, Robert L Parisien, Thomas S Bottiglieri, Christopher S Ahmad, David P Trofa
Summary: Nearly 3 million children participate in youth soccer annually in the United States. Popularity of youth soccer within recent years has prompted investigation describing youth-soccer concussion trends presenting to United States emergency departments (EDs). Data from National Electronic Injury Surveillance System were analyzed for soccer players 2 to 18 years old sustaining concussions from January 2013 to December 2022. Patient data included age, sex, mechanism of injury, setting (practice vs. game), diagnosis, loss of consciousness, and disposition. Raw data were used to calculate national estimates based on assigned statistical sample weight of each hospital. A total of 80,582 youth soccer concussions were diagnosed in US EDs (51.0% female, 49.0% male). The most common mechanism of injury was head to ball (31.0%). On average, overall concussions decreased by 572 per year (p = 0.02). Head to body concussions decreased by 169 per year (p < 0.01) and head to ground concussions decreased by 155 per year (p < 0.01). No changes per year in concussion trends for head to ball, head to head, not specified, and other mechanisms. Exclusion of years 2020 and 2021 (COVID), demonstrated decreases in concussions for head to body by 125 (p = 0.01) and head to ground mechanisms by 135 per year (p = 0.01). There is a decreasing trend in youth soccer head injuries and concussions presenting to US emergency departments from 2013 to 2022. The trends from this study indicate that heading may be the most important aspect of soccer-related concussions presenting to US emergency departments. This study contributes to the growing literature regarding concussions in youth soccer athletes.
7 Effects of soccer instruction on the executive functions and agility of children in early childhood
Reference: PLoS One. 2024 Oct 23;19(10):e0312265. doi: 10.1371/journal.pone.0312265. eCollection 2024.
Authors: Sho Aoyama
Download link: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0312265
Summary: Studies have shown that in open-skill sports the executive function of high-performing players is significantly higher than that of the control group. However, whether participation in soccer effectively improves executive function is unclear because previous studies lacked baseline measurements of executive function. Furthermore, agility, mostly developed in early childhood, is the most demanding component of physical fitness in open-skill sports, requiring sudden changes in body direction while running at full speed. However, no studies have examined the improvement in agility of young children participating in open-skill sports through comparison with a control group. This study aimed to clarify whether instruction in soccer, an open-skill sport, can effectively improve the executive function and agility of kindergarteners compared to a control group. In April 2020, 31 five-year-old children enrolled in kindergarten K in H prefecture in Japan were targeted as the intervention group and received soccer instruction for 12 weeks. In April 2020, a control group was established, consisting of 39 five-year-old children enrolled at the same kindergarten. Participants in both groups were measured for agility, inhibition, and working memory before and after (pre-post) soccer instruction for the intervention group. For each item, a two-way ANOVA of the group (intervention group・control group) x measurement period (pre-post) was performed, showing no significant interactions for working memory and agility. Because only the inhibition effect was significant, simple main effects were tested. Regarding inhibition, although the intervention group (M = 0.18, SD = 0.01) and the control group (M = 0.17, SD = 0.01) did not differ significantly in performance pre-intervention, the intervention group (M = 0.23, SD = 0.01) showed significantly better performance post-intervention compared to the control group (M = 0.19, SD = 0.01) (p < .01). Thus, soccer instruction improved kindergarteners‘ inhibition, to a level significantly higher than that of the control group. Still, no differences were found between groups regarding working memory and agility.
8 The frequency of injuries of Iranian male professional soccer players: a cross-sectional study
Reference: J Inj Violence Res. 2024 Oct 13;16(2). doi: 10.5249/jivr.v16i2.1897. Online ahead of print.
Authors: Tohid Seif Barghi, Salman Khazaei, Bijan Heydari, Homa Naderifar
Summary: Soccer is known to be a sport that carries a high risk of injuries due to its physical nature, involving intense contact and rapid movements like acceleration, deceleration, jumping, and sudden changes in direction. Compared to other sports, soccer is considered a contact sport with a heightened injury risk. The primary objective of this study was to assess the prevalence of sports injuries among professional soccer players. In this cross-sectional study, 56 male professional footballers participated to assess their injuries. The Pre-Competition Medical Assessment (PCMA) was utilized as the standard protocol for evaluating the athletes. The study examined variables such as injury type, player position on the field, and body mass index (BMI) in accordance with the FIFA-recommended PCMA guidelines. Student t-test was used to compare demographic characteristics injured and healthy athlete. Chi square and fisher exact tests were used to assess the association between player position, injury type and BMI classification. In this study, the mean age of the soccer players was 19.38 ± 1.30 years, with a history of participating in 3 to 60 matches. The highest incidence of injuries was recorded in the knee (48.21%) and ankle (30.36%), respectively. A significant relationship was found between the players‘ positions on the field and knee pain, with strikers experiencing more knee pain compared to players in other positions (p less than 0.04). However, no significant association was observed between the players‘ BMI and the occurrence of sports injuries (p greater than 0.05). Given the widespread occurrence of knee injuries among footballers, particularly in attacking players, proper planning and appropriate training protocols would be useful to prevent knee injuries and reduce treatment costs.
9 Ventilatory thresholds in professional female soccer players
Reference: Int J Sports Med. 2024 Oct 22. doi: 10.1055/a-2421-9272. Online ahead of print.
Authors: Koulla Parpa, Marcos A Michaelides
Summary: This study investigated the ventilatory thresholds (VT1 and VT2) along with the corresponding heart rates, velocities and % of V̇O2 max at which these thresholds are reached in professional female soccer players. It also examined positional differences in the aforementioned parameters. Thirty-three professional players from two teams (age range 18-31 years) were recruited. The players underwent maximal exercise testing on the treadmill for the detection of VT1 (V̇E versus V̇O2 plot) and VT2 (V̇E versus V̇CO2 plot). The test began at a speed of 6km/h and was increased by 2 km/h every 3.15 minutes, with the inclination constant at 1%. Results indicated that the players had an average V̇O2 max of 50.24 ml·kg- 1.min- 1. VT1 (% max) and VT2 (% max) were shown at 72.87% and 91.26% of V̇O2 max, respectively. The respective velocities at VT1 and VT2 were indicated at 10.85 km/h and 12.91 km/h, respectively, while the average VV̇O2 max was 14.61 km/h. The average heart rates at VT1, VT2 and V̇O2 max were 159.33, 185.15 and 192.85 beats per minute, respectively. Furthermore, analysis of variance ANOVA indicated significant differences in velocity at V̇O2max. This study provides important normative data regarding the ventilatory thresholds of female soccer players.
10 Factors Associated With a Successful Return to Performance After Anterior Cruciate Ligament Reconstruction: A Multiparametric Evaluation in Soccer Players
Reference: Orthop J Sports Med. 2024 Oct 8;12(10):23259671241275663. doi: 10.1177/23259671241275663. eCollection 2024 Oct.
Authors: Michele Mercurio, Simone Cerciello, Katia Corona, Germano Guerra, Roberto Simonetta, Filippo Familiari, Olimpio Galasso, Giorgio Gasparini
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11490974/pdf/10.1177_23259671241275663.pdf
Summary: Anterior cruciate ligament reconstruction (ACLR) is highly recommended in patients with ACL deficiency who must perform at a high physical level. A combination of functional and psychological outcome measures is necessary to provide a comprehensive evaluation of functional status after successful return to sport after ACLR. The aim was to identify factors associated with higher functional outcomes among soccer players who had returned to full sports participation after ACLR. A total of 168 out of 231 patients who underwent primary unilateral arthroscopic anatomic single-bundle ACLR were available at follow-up. Postoperatively, knee function, generic health outcomes, and psychological impact were assessed using the International Knee Documentation Committee (IKDC), the Knee injury and Osteoarthritis Outcome Score (KOOS), the Lysholm Knee Scoring Scale, the 12-item Short Form Health Survey (SF-12), and the ACL-Return to Sport after Injury scale. After a mean follow-up of 35.5 ± 22.6 months, 85% of soccer players returned to performance. Midfielder position was associated with a better SF-12 Physical Component Summary (PCS) score (P = .013), IKDC (P = .003), total KOOS (P < .001), KOOS Symptoms (P = .004), KOOS Pain (P = .029), KOOS Activities of Daily Living (ADL) (P = .044), KOOS Sport and Recreation (Sport/Rec) (P = .001), KOOS Quality of Life (QoL) (P < .001), and Lysholm score (P = .008). Playing only on natural grass was associated with lower SF-12 PCS scores (P = .003), total KOOS (P = .001), and KOOS Sport/Rec (P = .011). Playing only on artificial turf was associated with lower Lysholm score (P = .018) and total KOOS (P = .014). The contact mechanism was associated with higher IKDC (P = .044) and KOOS QoL (P = .048), and injury affecting the dominant limb was associated with lower SF-12 Mental Component Summary scores (P = .012). Playing at a nonprofessional level was associated with lower total KOOS (P = .028), KOOS Symptoms (P = .002), KOOS ADL (P = .033), and KOOS Sport/Rec (P = .016). Professional soccer players and the midfielder position are associated with better functional scores upon returning to the sport. A history of noncontact ACL injury and playing on a single type of surface are associated with lower functional outcomes upon returning to the sport. Lower mental health scores can be expected after injury of the dominant limb.
11 No transfer of 3D-Multiple Object Tracking training on game performance in soccer: a follow-up study
Reference: Psychol Sport Exerc. 2024 Oct 18:102770. doi: 10.1016/j.psychsport.2024.102770. Online ahead of print.
Authors: Romeas Thomas, Goujat Maëlle, Faubert Jocelyn, Labbé David
Summary: The impact of domain-general cognitive ‚brain‘ training on improving sports performance is highly debated. This study sought to follow-up on research that showcased the benefits of perceptual-cognitive 3D-Multiple Object Tracking (3D-MOT) training in enhancing the on-field performance of soccer players. Additionally, it explored the correlation between athletes‘ cognitive performance and early career success. Sixty-two males from a professional soccer academy were randomly divided into a dual-task 3D-MOT training group (n=30) and a control group (n=32). Participants underwent a 3D-MOT test, a cognitive test of attention, and small-sided games at pre- and post-training. Pre-post-test performances were compared using ANCOVAs. A Chi-squared test evaluated the association between the training regimen and early career success. A Spearman test assessed the correlation between performance on the 3D-MOT, attention test, and early career success. The dual-task 3D-MOT trained group significantly improved its performance on 3D-MOT compared to the control group (p < 0.001). However, no significant pre-post-test differences were observed between the groups in the near-transfer cognitive test and on-field performance (ps > 0.05). There were no associations between the athletes‘ early career success and the training regimen, and no associations between cognitive test performances and early career success (ps > 0.05). This follow-up study failed to replicate previous findings with dual-task 3D-MOT training unable to produce near or far transfer on soccer performance. In addition, cognitive performance was not related to early career success in this study. The value of cognitive screening and training in sport is discussed.
12 Prescription criteria and effects of explosive strength training in indoor soccer players: a systematic review
Reference: Eur J Transl Myol. 2024 Oct 17. doi: 10.4081/ejtm.2024.12888. Online ahead of print.
Authors: Ana Belén Guzmán, Rubén Vidal-Espinoza, Luis Urzua-Alul, Luis Felipe Castelli Correia de Campos, José Fuentes-López, Camilo Urra-Albornoz, Marco Cossio-Bolaños, Rossana Gomez-Campos
Download link: https://www.pagepressjournals.org/bam/article/view/12888/12458
Summary: Explosive strength is fundamental in the performance of athletes. The objective is to identify the criteria used for the prescription of Explosive Strength Training (EST) and to verify the changes it produces in futsal players. A systematic review of studies analyzing the criteria used for the prescription of explosive strength training was conducted in PubMed/MEDLINE and Scielo, considering the period between 2017 and 2023. The search strategy used the terms: players, Futsal, Futsal training, strength, physical exercise, explosive strength, intervention, experimental study. Data extraction included: year of publication, country, sample, protocol performed (content and activity developed, duration, intensity, frequency, total weeks). A total of six studies were identified. Fifty percent of the studies were developed in Brazil, the others in Italy, Spain and Portugal. Five studies applied a training of 2 sessions per week and one indicated 2-3 sessions. Three studies describe the training sessions (study 1: 15-30 minutes, study 2: 20-25 minutes, study 3: 1 hour). Five studies used 1RM and one study used subjective perception of exertion (PSE). The contents of the interventions were varied, from squats with weights, accelerations and decelerations, leg press, leg extension, plyometrics. The training criteria for explosive strength were: intensity controlled by a 1RM, frequency of 2 to 3 sessions per week, duration of 15 to 30 minutes per session and the training contents were varied. These results suggest positive changes in CMJ, increasing explosive strength from ∼2.0 to 4.6 cm (5.8 to 13.7%). These findings highlight the need to develop a more standardized protocol to optimize the benefits of explosive strength training in this athletic population.
13 Saliva as a diagnostic tool in soccer: a scoping review
Reference: PeerJ. 2024 Oct 14:12:e18032. doi: 10.7717/peerj.18032. eCollection 2024.
Authors: Joyce Ferreira, Manuel Jimenez, Agatha Cerqueira, Joana Rodrigues da Silva, Bruno Souza, Lucas Berard, Andre L L Bachi, Naile Dame-Teixeira, Neide Coto, Debora Heller
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11485103/pdf/peerj-12-18032.pdf
Summary: A high-performance sport like soccer requires training strategies that aim to reach peak performance at the right time for the desired competitions. Thus, the investigation of biochemical markers in saliva is a tool that is beginning to be used in athletes within the physical training process. There is still no evidence on universal saliva collection and analysis protocols in soccer. This review aims to map the use of saliva as a tool for analyzing athletic performance in soccer, from the biomarkers used to the validated protocols for these analyses. A broad systematic literature search was carried out in the electronic databases Web of Science, Livivo, Scopus, PubMed, LILACS and gray literature (Google Scholar and ProQuest). Two reviewers selected the studies and extracted data on the type of salivary collection used, the salivary biomarker evaluated and monitored. Ninety-three articles were included. The most frequently analyzed salivary biomarkers were cortisol (n = 53), testosterone (n = 35), secretory immunoglobulin A (SIgA) (n = 33), salivary alpha amylase (n = 7), genetic polymorphisms (n = 4) and miRNAs (n = 2). The results of the studies indicated beneficial effects in monitoring salivary biomarkers in the assessment of sports performance, although most studies did not include a control group capable of comparison. Salivary collection and analysis protocols were varied and commonly not reported. This scoping review provides a comprehensive overview of the current landscape of salivary biomarker research in soccer. The findings underscore the importance of these biomarkers in assessing athletes‘ physiological responses and overall well-being. Future research should focus on refining methodologies, exploring additional biomarkers, and investigating the practical implications of salivary biomarker monitoring in soccer and other sports.
14 The relationships between distances covered above generic and relative speed thresholds by male soccer players in English Premier League matches across two competitive seasons. The effects of positional demands and possession
Reference: Biol Sport. 2024 Oct;41(4):77-86. doi: 10.5114/biolsport.2024.135416. Epub 2024 Mar 18.
Authors: Ronan Kavanagh, Rocco Di Michele, Rafael Oliveira, Kevin McDaid, David Rhodes, Ryland Morgans
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11474994/pdf/JBS-41-52398.pdf
Summary: The aims of this study were to: a) examine the relationships between high-intensity distances covered above generic and relative speed thresholds in English Premier League (EPL) matches across two consecutive seasons and b) analyze the effects of playing position and team possession. Sixteen elite male soccer players (seven defenders, six midfielders and three forwards) participated in this study (age 27.8 ± 3.5 years, height 183.7 ± 5.4 cm, body mass 83.9 ± 7.1 kg). An Optical Tracking System was used to collect the following variables: total distance covered; high-speed running distance (HSRD) (> 5.5 m/s); high-intensity running distance (HIRD) (5.5-7 m/s); sprint distance (> 7 m/s); total distance covered above Maximal Aerobic Speed (MAS); distance covered > 85% peak speed (PS); and distance > 30% Anaerobic Speed Reserve (ASR). All measures were analyzed as whole match totals and as distances covered in the periods of the team in possession (TIP), opponent team in possession (OTIP), and ball out of play (BOP). Analysis by position based on defenders, midfielders and forwards was also performed. Distance > 30% ASR was almost perfectly correlated with HSRD (r = 0.98), while distances > MAS were highly correlated with both HIRD (r = 0.91) and HSRD (r = 0.91), and distance > 85% PS were highly correlated with SD (r = 0.70). Although the generic and relative speed thresholds show almost perfect correlation, the differences between HSRD, HIRD and distance > MAS indicate that players may be exposed to more HIRD when using relative thresholds.
15 Effects of linear and change of direction high-intensity interval training on physical performance of elite female soccer players
Reference: Biol Sport. 2024 Oct;41(4):31-39. doi: 10.5114/biolsport.2024.134761. Epub 2024 Mar 6.
Authors: Mima Stanković, Nebojša Trajković, Draženka Mačak, Dušan Đorđević, Anja Lazić, Zoran Milanović
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11475003/pdf/JBS-41-52318.pdf
Summary: The aim of this study was to determine the effects of linear and change of direction high-intensity interval training (HIIT) on physical performance in elite female soccer players. Thirty elite female soccer players (age: 19.6 ± 4.6 years; height: 166.5 ± 4.8 cm; body weight: 60.5 ± 8.3 kg; BMI: 21.9 ± 2.9 kg/m2) were randomly allocated to HIIT linear (HIITLIN) and HIIT change of direction (HIITCOD) training groups. The HIITLIN group performed linear running for 15, 20 or 25 s by keeping constant pace during the entire distance. In contrast, the HIITCOD group performed three changes of direction (COD) with a 180° turn during each interval run at 15, 20 or 25 s. Physical performance was assessed using sprinting, agility, vertical jumps, repeated sprint ability (RSA) and 30-15 Intermittent Fitness Test (30-15 IFT). In both groups, all physical performance measurements improved (p ≤ 0.05), except RSAbest in HIITLIN (p = 0.45). Both interventions significantly improved speed over 10 m, 20 m, 30 m, Pro-agility, Zig-zag, RSAavg, fatigue index, maximal oxygen uptake, and velocity at 30-15 IFT, while moderate improvements were observed in countermovement jump (CMJ), CMJ with arm swing and squat jump. However, HIITCOD did not achieve superior improvements in any of the aforementioned measurements compared to HIITLIN. Based on the obtained results, we concluded that different types of HIIT training have a positive effect on physical performance in elite female soccer players.
16 Balancing the load: A narrative review with methodological implications of compensatory training strategies for non-starting soccer players
Reference: Biol Sport. 2024 Oct;41(4):173-185. doi: 10.5114/biolsport.2024.139071. Epub 2024 Apr 25.
Authors: Filipe Manuel Clemente, Guglielmo Pillitteri, Luiz H Palucci Vieira, Alireza Rabbani, Piotr Zmijewski, Marco Beato
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11475008/pdf/JBS-41-54003.pdf
Summary: New training approaches have emerged advocating for the implementation of compensatory physical training. This approach aims to provide additional training that balances the load typically experienced by non-starters during a match. This may help maintain their readiness and ensures that their physical fitness is not compromised by the reduced exposure to match loads. Thus, this narrative review aims to describe the differences in external loads between starting and non-starting players and describe the studies conducted in compensatory training. Studies examining external load metrics such as total distances covered, high-speed running, and sprinting suggest that, adjusted for playing time, values are often higher in non-starting players. Although not standardized, there is an obvious decrease in exposure for these critical variables in non-starters. Additionally, internal load parameters such as perceived exertion and heart rate tend to be higher in starting players. Regarding the physical fitness impacts, evidence suggests differences observed between starters and non-starters in some aspects of physical performance, although the extent and significance of these differences can vary. The studies on compensatory training are limited, and the typical approach usually centres on running-based exercises and small-sided games, offering differing approaches to address the physical needs. The gap in research underscores the necessity for improved study designs that can shed light on the real impact of compensatory training. Presently, the practice of compensatory training has been adopted, yet a definitive understanding of its genuine influence, particularly in terms of enhancing physical fitness and mitigating injury risks, remains elusive.
17 Relative age effect across the talent identification process of youth female soccer players in the United States: Influence of birth year, position, biological maturation, and skill level
Reference: Biol Sport. 2024 Oct;41(4):241-251. doi: 10.5114/biolsport.2024.136085. Epub 2024 May 17.
Authors: Laura Finnegan, Mirelle van Rijbroek, José M Oliva-Lozano, Rick Cost, Matthew Andrew
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11475004/pdf/JBS-41-52572.pdf
Summary: The aims of the study were to examine the relative age effect (RAE) in youth female soccer players in the United States (US) and the influence of birth year, playing position, estimated maturation and skill ratings. The sample consisted of 3,364 youth female soccer players who were active in the 2021-2022 US soccer season across three main stages of the talent identification (TID) process for Youth National Team (YNT) players (i.e., Club, TID Center, and YNT). A prevalent RAE for players born in Q1 was present in the full sample. A significant prevalence for Q1 players were identified for both Club and TID Center, but not YNT. A significant RAE prevalence for Q1 players was identified for most of the age groups from U13-U18 at Club (except U18) and TID Center (except U17). Significant RAEs prevalence for players born in Q1 were found in Goalkeepers, Center Backs, Midfielders, and Center Forwards at Club and TID Center (except Wide Forwards). The data identified a consistent RAE prevalence for Q1 players in early and on-time-maturers across all levels. An even birthdate spread was evident in YNT with a prevalence for Q4 players and a higher percentage of late-maturers than elsewhere in the TID process. Results reinforce evidence indicating RAEs still exist in soccer, yet show for the first time within a youth female soccer TID process, the influence of contextual factors on the prevalence of RAE. This information can be used to advance TID and development across the US soccer landscape.
18 Influence of contextual factors on most demanding scenarios in under-19 professional soccer players
Reference: Biol Sport. 2024 Oct;41(4):51-60. doi: 10.5114/biolsport.2024.136087. Epub 2024 Mar 6.
Authors: Rubén-Cipriano Romero-Rodríguez, Enrique Alonso-Pérez-Chao, Carlos Ribas, Daniel Memmert, Miguel-Ángel Gómez-Ruano
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11475010/pdf/JBS-41-52574.pdf
Summary: This study aimed to compare the most demanding scenarios (MDS) of under-19 professional soccer players during official matches, controlling for contextual factors such as playing position, the level of opponent teams, playing venue, match status, playing surface, pitch size, and playing status of players. A total of 42 players were monitored across 27 games using Global Positioning System (GPS) technology to collect the external loads, including total distance covered, high-speed running, sprint distance, accelerations, and decelerations. MDS were calculated across 1-minute, 5-minute, and 10-minute time windows for each variable. Significant differences were found based on the contextual factors. (i) Opponent level did not show significant differences; (ii) full-backs covered more distance at 1 minute in home games; (iii) midfielders in winning vs. drawing scenarios exhibited higher decelerations at 1 minute but less distance at 10 minutes; (iv) in drawing vs. losing scenarios, central defenders had greater distance at 5 minutes and accelerations at 5 minutes, while midfielders showed greater distances at 1 minute, 5 minutes, and 10 minutes; (v) offensive midfielders and forwards displayed specific performance differences; (vi) no significant differences were found for the playing surface; (vii) regarding pitch size, full-backs covered more distance at 5 minutes on larger pitches, while midfielders covered more distance at 5 minutes and 10 minutes; and (viii) starters generally outperformed non-starter players across various variables depending on the playing positions. The findings suggest that contextual factors have a significant impact on soccer player performance across different playing positions.
19 Characterizing microcycles‘ workload when combining two days structure within single training sessions during congested fixtures in an elite male soccer team
Reference: Biol Sport. 2024 Oct;41(4):87-100. doi: 10.5114/biolsport.2024.132992. Epub 2024 Mar 18.
Authors: Antonio Gómez-Díaz, Fábio Yuzo Nakamura, Pedro Menezes, João Barreira, Pedro Figueiredo, Diogo Coutinho
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11474999/pdf/JBS-41-51821.pdf
Summary: This study aimed to describe and compare specific matchdays sessions and playing positions external load during congested fixtures in elite football when combining the objectives from two different training days in one session. Data was collected from 27 players from the 1st Brazilian division (28.7 ± 18.61 years) that participated in the following training days during congested fixtures (n = 16 weeks): a) Match day+1 (MD+1MD-2, session 1 day after the game with tasks from MD+1 and MD-2 sessions, n = 9); b) Matchday-2 (MD-2MD+2, session 2 days prior to subsequent match with tasks from MD-2 and MD+2 sessions, n = 11); c) Matchday-1 (MD-1MD+2, session 1 day prior to subsequent match with tasks from MD-1 and MD+2 sessions, n = 12); and d) Matchday-1 (MD-1MD+3, session 1 day prior to subsequent match with tasks from MD-1 and MD+3 sessions, n = 11). External load was collected with global positioning systems, while internal load with the rating of perceived exertion (RPE). The MD+1MD-2 showed higher total distance covered (F = 116.92, p < 0.001) and player load (F = 56.67, p < 0.001) values than the other three training days, while both the MD+1MD-2 and MD-2MD+2 revealed higher distance covered at high-speed running (F = 22.43, p < 0.001) and high metabolic load distance covered (F = 75.98, p < 0.001) than both MD-1 sessions. Fullbacks covered higher high-speed running distance (F = 3.6, p = 0.033) than center backs, while midfielders reported higher RPE (F = 5.29, p = 0.003) values than defensive midfielders and fullbacks. Coaches may use the MD+1MD-2 to emphasize total distance covered, while both MD+1MD-2 and MD-2MD+2 to promote HSR and HML distance compared to MD-1 sessions. In addition, combining training sessions allows to normalize external load across playing positions with the exception of fullbacks that are exposed to higher stimulus.
20 Possession or position games: What is the key in soccer?
Reference: Biol Sport. 2024 Oct;41(4):109-117. doi: 10.5114/biolsport.2024.136086. Epub 2024 Apr 8.
Authors: Jose A Asian-Clemente, Borja Muñoz, Jose Vicente Beltran-Garrido, Bernardo Requena
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11475009/pdf/JBS-41-52573.pdf
Summary: The aims of this study were to compare the running performance of possession and position games and to describe the external load of the same position game played on pitches of different dimensions. Using a GPS system (WIMU Pro, RealTrack Systems, Almería, Spain), the running demands of 25 professional soccer players were monitored during 18 possession (without a standardized role position) and 18 positional (with a specific role position) games of 9 vs. 9 + 2 floaters. Each format was developed in small (< 60 m2 per payer), medium (60-90 m2 per player) and large (> 90 m2 per player) sizes. Position games obtained significantly lower distance covered, peak speed and player load values than possession games (all p < 0.05). However, position games obtained significantly higher values of maximal acceleration, maximal deceleration, accelerations higher than 3 m · s-2 and decelerations lower than -3 m · s-2 than possession games (all p < 0.05). Likewise, large position games obtained significantly higher values of distance covered, distance covered > 21 km · h-1, peak speed and player load than small and medium sizes. Large size also showed significantly higher values of maximal acceleration and deceleration than small size, significantly fewer accelerations and decelerations, and fewer accelerations lower than 3 m · s-2 and decelerations higher than -3 m · s-2 compared to medium and small size (all p < 0.05). Practitioners should keep in mind the use of these games and their size to modify the external load of the players during their training.
21 The association between aerobic capacity and spinal curvature and mobility in young soccer players
Reference: Gait Posture. 2024 Oct 6:114:235-242. doi: 10.1016/j.gaitpost.2024.10.004. Online ahead of print.
Authors: Elvan Felekoglu, Ilknur Naz, Umut Ziya Kocak, Sevtap Gunay Ucurum, Melissa Kopruluoglu, Merve Keskin, Derya Ozer Kaya
Summary: There is a lot of research in terms of injuries and performance in football and nowadays aerobic capacity, spinal posture and mobility have been taken into consideration separately in terms of performance. Considering from a biomechanical perspective, we thought spinal curvature and mobility may affect aerobic performance and investigated the relationship between them. Our research question was if young soccer players‘ segmental spinal curvature and mobility affect their aerobic capacity and maximal exercise performance? Thirty-four young league players (mean age 16.56 ±1.11 years) were evaluated pre-season. Spinal assessments in the sagittal plane with a non-invasive, computer-assisted electromechanical device and aerobic capacity assessment with a cardiopulmonary exercise-testing device were applied. The relationship between spinal postural variables with aerobic capacity was done by Pearson correlation analysis, and simple linear regression analysis was used to estimate the effect of spinal curvature and mobility on aerobic performance. Various parameters of aerobic performance were related to spinal curvature and mobility. Maximal oxygen uptake (VO2max) and maximal heart rate (HRmax) were negatively correlated with thoracic angle (r=-0.343, p=0.047 and r=-0.344, p=0.046; respectively). Thoracic angle was also associated with tidal volume (VT) and VO2/HR (r=-0.347, p=0.044 and r=-0.348, p=0.044; respectively). Higher thoracic mobility caused to reach the anaerobic threshold (VAT) earlier (r=-0.368, p=0.032), at a lower speed (r=-0.367, p=0.033). In other segments, lumbar mobility was negatively correlated with VT at VAT (r=-0.346; p=0.045), while spinal inclination with HR at VAT (r=-0.387, p=0.024). Although it is within physiological ranges, increased spinal curvature and mobility are associated with a decrease in aerobic capacity in young soccer players. Spinal curvature and mobility especially in the thoracic region may affect the aerobic performance of a soccer player. The trainers should consider spinal alignment for not only the technical and tactical but also the general performance of the soccer player.
22 Neuropsychophysiological Aspects of Soccer Performance: A Bibliometric Analysis and Narrative Review
Reference: Percept Mot Skills. 2024 Oct 16:315125241292969. doi: 10.1177/00315125241292969. Online ahead of print.
Authors: Spyridon Plakias, Georgia Karakitsiou
Summary: In recent years, there has been growing scientific interest in the neuropsychophysiological aspects of soccer performance. The purpose of this study was to conduct a bibliometric analysis to identify and review key topics within the neuropsychophysiological dimensions of soccer performance and identify any research voids that warrant further attention. We retrieved 192 documents from the Scopus database and anayzed the extracted data using VOSviewer software to conduct a bibliometric analysis. We applied both performance analysis techniques (including the number of documents per year, top 20 authors by citations, and top 15 sources by documents) and science mapping analysis (co-authorship, bibliographic coupling, co-citation, and co-occurrence). The co-occurrence analysis identified three main clusters of research themes. The first cluster focused on the relationship between physical performance and cognitive factors, the second on technical-tactical performance, and the third on health and well-being. Our findings emphasize the significant role of neuropsychophysiological factors in all aspects of soccer performance. We highlight the importance of integrating cognitive and physical training to enhance player performance and underscore the need for further research to deepen our understanding of these relationships.
23 Effects of an 8-week pre-season targeted training on sprinting performance, agility and lower limb muscular asymmetries in elite soccer players
Reference: Biol Sport. 2024 Oct;41(4):69-76. doi: 10.5114/biolsport.2024.134754. Epub 2024 Mar 6.
Authors: Artur Gołaś, Przemysław Pietraszewski, Robert Roczniok, Artur Terbalyan, Adam Maszczyk, Rafał Opaliński, Adam Zając
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11474991/pdf/JBS-41-52312.pdf
Summary: The purpose of this study was to determine the effects of an 8 week targeted training program on speed, agility, and muscle asymmetries in soccer players. 32 elite soccer players were recruited for the study. Their age, body mass, and body height were 25.8 ± 7.3 years, 77.4 ± 11.1 kg, and 177.5 ± 9.8 cm, respectively. After the warm-up, participants performed two maximum 30 m sprints with a 5-minute rest interval between trials. After the linear sprint test, performed two repetitions of the COD randomized ZigZag test. The tests were performed at the beginning and at the end of the pre-season, which lasted for 8 weeks. EMG was measured bilaterally from the quadriceps, hamstrings, and gluteal muscles with shorts made of knitted fabric similar to elastic clothes. Athletes in the experimental group performed sport-specific targeted strength training based on movement patterns 4 times per week (Monday, Tuesday, Thursday, and Friday). The training included 6 bodyweight exercises (Bird Dog, Single-Leg Glute Bridge, Dead Bug, Side Plank, Reverse Lunge, and Clamshell), performed unilaterally in 5 sets of 10 repetitions of each exercise. The load progression included an additional set in each successive week of the experiment. The data analysis showed significant improvement in 5 m and 30 m sprints after applying the 8-week targeted training protocol. A statistically significant improvement in performance was also observed after the 8-week training period in case of COD, while the speed deficit also decreased significantly. The greatest improvements were observed during the COD test. As a result of repeated COD training over a period of 8 weeks, its technique was improved. Implementation of training methods, which target specific aspects of soccer in the pre-season training routines can improve key motor abilities for that sports discipline. A comprehensive training approach including speed, agility, and resistance training based on specific movement patterns should be applied by strength and conditioning practitioners in soccer teams to achieve peak physical performance and reduce injury risk due to the partial elimination of muscular asymmetries.
24 Functional and Structural Long-Term Effects of Repetitive Instrument-Assisted Manual Therapy (IAMT) of the Lumbar Back on the Dorsal Myofascial Chain Among Female Soccer Players: A Randomized, Placebo-Controlled Pilot Trial
Reference: Cureus. 2024 Sep 13;16(9):e69337. doi: 10.7759/cureus.69337. eCollection 2024 Sep.
Authors: Patrick Weber, Werner Klingler, Robert Schleip, Nadine Weber, Christine Joisten
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11471137/pdf/cureus-0016-00000069337.pdf
Summary: Instrument-assisted manual therapy (IAMT) is suitable for optimizing movement prerequisites, such as range of motion, flexibility, microcirculation, and pain inhibition along myofascial chains, potentially leading to a reduction in hamstring injuries. To date, however, IAMT’s modes of action remain largely unclear. This study aimed to examine the functional and structural effects of repetitive IAMT after 2.5 and five weeks. Sixteen healthy female soccer players (age: 21.4 (±5.1) years) were randomly grouped into an intervention group and a placebo control group. The intervention group received nine IAMT sessions twice weekly at the right lumbar region. The placebo group received a single pressureless „therapy“ at baseline. In addition to structural ultrasound analyses (absolute motion and shear motion), functional mobility tests (passive straight leg raise (PSLR) test and lumbar and thoracic double inclinometry) were performed 4.0 (±2.0) days after the fourth IAMT and 3.4 (±1.1) days after the ninth IAMT in both groups. Hamstring flexibility in the PSLR test improved significantly after the ninth IAMT compared with the placebo group (p < 0.05, effect size: 0.913). No systematic differences were seen at the structural level. Repetitive IAMT can improve hamstring flexibility. Further studies in larger groups and diverse collectives are necessary to additionally test the postulated preventive effect also on hamstring injuries. Whether ultrasound is the right method for detecting structural changes in this context needs to be verified in the future.
25 A soccer-based intervention improves incarcerated individuals‘ behaviour and public acceptance through group bonding
Reference: Nat Hum Behav. 2024 Oct 14. doi: 10.1038/s41562-024-02006-3. Online ahead of print.
Authors: Martha Newson, Linus Peitz, Jack Cunliffe, Harvey Whitehouse
Download link: https://www.nature.com/articles/s41562-024-02006-3
Summary: As incarceration rates rise globally, the need to reduce re-offending grows increasingly urgent. We investigate whether positive group bonds can improve behaviours among incarcerated people via a unique soccer-based prison intervention, the Twinning Project. We analyse effects of participation compared to a control group (study 1, n = 676, n = 1,874 control cases) and longitudinal patterns of social cohesion underlying these effects (study 2, n = 388) in the United Kingdom. We also explore desistance from crime after release (study 3, n = 249) in the United Kingdom and the United States. As law-abiding behaviour also requires a supportive receiving community, we assessed factors influencing willingness to employ formerly incarcerated people in online samples in the United Kingdom and the United States (studies 4-9, n = 1,797). Results indicate that social bonding relates to both improved behaviour within prison and increased willingness of receiving communities to support re-integration efforts. Harnessing the power of group identities both within prison and receiving communities can help to address the global incarceration crisis.
26 Reliability of single-leg maximal dynamic strength performance and inter-limb asymmetries in pre-pubertal soccer players. The influence of maturity in asymmetries
Reference: Heliyon. 2024 Sep 28;10(19):e38716. doi: 10.1016/j.heliyon.2024.e38716. eCollection 2024 Oct 15.
Authors: Nizar Bouafif, Raouf Hammami, Abdelkader Mahmoudi, Pablo Jiménez-Martínez, Carlos Alix-Fages, Amador Garcia-Ramos, Alvaro Juesas, Javier Gene-Morales, Sabri Gaied-Chortane, Juan C Colado
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11471460/pdf/main.pdf
Summary: The aims of this repeated measures study were (I) to determine the reliability of single-leg squat 1RM and inter-limb asymmetries in pre-pubertal athletes, and (II) to assess associations between bilateral and/or unilateral squat 1RM performance, inter-limb asymmetries, and participants‘ chronological and biological age. Thirty-one soccer players (age [mean ± standard deviation] = 8.48 ± 0.47 years; body mass = 28.32 ± 3.47 kg; body height = 121.70 ± 4.11 cm) practiced two familiarization and two experimental sessions. Bilateral and unilateral squat 1RM and asymmetries between both legs were assessed. Biological age was obtained through the age at peak height velocity (12.87 ± 0.38 years) and maturity offset (3.92 ± 0.44 years). Absolute and relative reliability and Pearson’s correlations were calculated. Right and left leg 1RM and asymmetries presented good relative reliability (ICCrange = 0.84-0.85) levels, but non-acceptable absolute reliability (CV ~ 12 %). Asymmetries presented trivial to small correlations with strength (Range = 0.01-0.11). Similarly, chronological, and biological age presented small correlations with strength and asymmetries (Range = 0.01-0.22). Considering the good reliability, the bilateral and unilateral 1RM back half squat test can be considered in youth soccer players. Finally, lower-body mechanical performance and asymmetry between legs show trivial to small correlations, with maturation not affecting asymmetry in male youth soccer players. In conclusion, strength and power activities and training should be placed on younger soccer players with high asymmetry scores regardless of their stage of maturation.
27 Injury surveillance in Spanish professional female soccer players: A three-season retrospective study
Reference: Injury. 2024 Sep 27;55(12):111922. doi: 10.1016/j.injury.2024.111922. Online ahead of print.
Authors: Ivan Medina-Porqueres, Sara Sancho-Garcia, Abel Gomez-Caceres, Rafael Mondragon-Cortes, Ana Madrid-Rodríguez, Daniel Rosado-Velazquez
Summary: Despite the popularity of soccer at the male elite level, data on the incidence of injuries in female players are limited. The study aimed to evaluate the injury incidence and rates in female soccer players in a professional setting over 3 consecutive seasons. Data compiled from 71 elite female players with different playing positions and belonging to the same team were analyzed. The location and severity of injuries were reported according to international consensus statements on the process of conducting epidemiological studies in professional soccer. The injury incidence rate (IIR) for matches and practices and the rate ratio (RR) were calculated, and time-loss injuries during the season were also recorded. A total of 53 injuries were documented, with an overall IIR of 1.08 injuries per 1000 h and an overall rate ratio of 0.61. The lower limbs were the most affected region (86,8 %). The majority of these injuries occurred around the thigh and knee and were predominantly traumatic, with markedly higher rates of injury during match play (2.78 injuries per 1000 h) when compared to injury incidence during training (0.79 injuries per 1000 h). Traumatic injuries accounted for 48 (91 %) and 24 (45,3 %) were indirect contact injuries. Reinjuries amounted to 15 % of total injuries and August was the predominant month for injury, being goalkeepers the least injured players (13.2 %). Female professional soccer players displayed injury incidence rates and patterns comparable to those of male players. This study provides epidemiological information that will help to inform future injury surveillance studies and the development of prevention strategies to reduce the number of injuries in elite female soccer players, focusing specifically on thigh and knee regions. All match involvements should be considered when exploring associations between the type of exposure and injury risk.
28 Spatial distribution characteristics and influencing factors of youth soccer specialty schools in China
Reference: Sci Rep. 2024 Oct 15;14(1):24109. doi: 10.1038/s41598-024-75489-9.
Authors: Yujin Zhou, Qiuhuan Chen, Dong He, Yu Cheng, Xiaowei Peng
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11480466/pdf/41598_2024_Article_75489.pdf
Summary: Youth soccer specialty schools are the primary project to strengthen the foundation of soccer talents, improve the level of soccer development, and achieve the dream of Chinese soccer. Taking 32,775 soccer specialty schools in China as the research sample, ArcGIS spatial analysis technology is used to explore the spatial distribution characteristics of soccer specialty schools and their influencing factors. The analysis shows that the overall distribution of the country forms five quantity concentration area and eight high-density core areas, with a high degree of spatial concentration and significant differences between the East and West. The factors influencing soccer specialty schools include nine factors in four dimensions: historical development, geographical environment, socio-economic, and educational resources. It was found that geographic environment and socio-economy provide the foundation and background for developing educational resources. However, the direct role of educational resources is more significant in a specific educational program, such as soccer specialty schools, followed by socio-economy and geographic environment. This study comprehensively analyzes and interprets soccer specialty schools‘ spatial distribution characteristics and influencing factors. These results enrich the research on the spatial layout of sports, providing necessary theoretical support and practical references for the layout and high-quality development of related industries in China and other countries or regions.
29 Implementation of a mixed-methods heat acclimation programme in a professional soccer referee before the 2022 FIFA world cup in Qatar: a case study
Reference: BMJ Open Sport Exerc Med. 2024 Oct 14;10(4):e002185. doi: 10.1136/bmjsem-2024-002185. eCollection 2024.
Authors: Dale B Read, Daniel T Evans, Simon Breivik, Joshua D Elliott, Oliver R Gibson, Laurence P Birdsey
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11474663/pdf/bmjsem-10-4.pdf
Summary: This case study reports the real-world practicalities of implementing a mixed-methods heat acclimation (HA) programme before the 2022 FIFA World Cup. One male English soccer referee (age: 44 years; height: 1.82 m; body mass: 76.0 kg) who had officiated professionally for over 17 years and had over 10 years‘ experience officiating in European and international matches undertook an 11-session HA programme over 22 days. On days 1 and 22, a 30 min fixed-intensity heat tolerance test (9 km.h-1, 2% gradient, 40°C, 40% relative humidity) was performed, and physiological and perceptual responses were measured. A mixed-methods HA approach was used, including environmental chamber isothermic training, post-temperate training saunas and hot water immersion. Compared with the pre-test, peak core temperature reduced by 0.40°C (38.4 vs 38.0°C; minimal detectable change (MDC) = 0.34°C), peak skin temperature reduced by 0.5°C (36.7 vs 36.2°C; MDC=0.28°C) and peak heart rate reduced by 5 b·min-1 (167 vs. 162 b·min-1; MDC=4 b·min-1) in the post-test. In the post-test, the sweat rate increased by 17% (1.94 vs 2.27 L.h-1; MDC=0.42 L.h-1). Peak thermal sensation (7 = ‚hot‘) and the rating of perceived exertion (3 = ‚moderate‘) were unchanged between the tests. However, peak thermal comfort (3 = ’slightly uncomfortable‘ vs 2 = ‚uncomfortable‘) was rated lower in the post-test. The HA programme elicited positive physiological but indifferent perceptual responses, highlighting that mixed-methods HA can be implemented when a referee still has officiating, travel and training responsibilities during the HA window.