Latest research in football - week 32 - 2022

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 Still poorly adopted in male professional football: but teams that used the Nordic Hamstring Exercise in team training had fewer hamstring injuries - a retrospective survey of 17 teams of the UEFA Elite Club Injury Study during the 2020-2021 season

Reference: BMJ Open Sport Exerc Med. 2022 Jul 22;8(3):e001368. doi: 10.1136/bmjsem-2022-001368. eCollection 2022.

Authors: Jan Ekstrand, Håkan Bengtsson, Markus Walden, Michael Davison, Martin Hagglund

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Summary: The primary objective was to study the adoption of the NHE programme in European football teams in the 2020/21 season and to compare it to the previous study. A second objective was to compare hamstring injury rates between teams that used the NHE programme in the team training and teams that used the NHE only for players with previous or current hamstring injuries. Data about the implementation of the NHE programme and injury rates were included for 17 teams participating in the Elite Club Injury Study during the 2020/2021 season. One team (6%) used the full original NHE programme, and another four teams used it for all or most players in the team (team training group, n=5). Eleven teams used NHE only for players with a previous or current hamstring injury (individual training group), and one team did not use NHE. The team training group had fewer hamstring injuries (5 vs 11 per team, p=0.008) and a lower injury burden (12 vs 35 lay-off days per 1000 hours, p=0.003) than the individual training group. Similar to previous reports, low adoption of the NHE programme was seen in the 2020/2021 season. The low adoption rate (13%) relates to the number of teams fully or partly using NHE programmes. Teams that used NHE for the whole team or most players had a lower hamstring injury burden than teams that used NHE only for individual players.



#2 Monitoring the post-match neuromuscular fatigue of young Turkish football players

Reference: Sci Rep. 2022 Aug 16;12(1):13835. doi: 10.1038/s41598-022-17831-7.

Authors: Zeki Akyildiz, Yücel Ocak, Filipe Manuel Clemente, Yasar Birgonul, Mehmet Günay, Hadi Nobari

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Summary: Neuromuscular fatigue tests have been used in previous studies to organize post-match training programs and to minimize injuries. The aim of this study is to describe the neuromuscular fatigue that occurs after a football match and to examine the relationship between internal and external load values in the match and fatigue parameters obtained at different time intervals. Twenty male U19 academy league soccer players (age: 19; height: 181.3 ± 4.3; weight: 73.4 ± 6.7) participated in the study. The countermovement jump (CMJ) test was applied to the players 24 h before, as well as 24, 48, 72, 96, and 120 h after a football match. During the CMJ tests, the maximum velocity of each player during the jump was recorded by using the GymAware linear position transducer. The CMJ maximum velocity values 24 h before and 24 h after the match, as well as the CMJ height values (Cohen's d: 1.210; p < 0.001), were statistically different from the values recorded 24 h before and 24 and 48 h after the match (Cohen's d: 1.578; p < 0.001; Cohen's d: 0,922; p < 0.009). The correlation values were not statistically significant. The results suggest, CMJ height and CMJ maximum velocity values, which determine neuromuscular fatigue after a football match, can be used by practitioners to display post-match neuromuscular fatigue measurements.



#3 Player-labelling as a solution to overcome maturation selection biases in youth football

Reference: J Sports Sci. 2022 Jul;40(14):1641-1647. doi: 10.1080/02640414.2022.2099077. Epub 2022 Aug 15.

Authors: Dennis Lüdin, Lars Donath, Stephen Cobley, David Mann, Michael Romann

Summary: The fact that potentially skilled, but biologically later-maturing athletes are less likely to be selected into talent development programmes (TDP) can represent a failure of Talent Identification (TID) in sports. To overcome maturation selection biases, maturation independent TID should be established to include less mature, but talented athletes in TDP more frequently. Using a randomised parallel-group design, this study aimed to evaluate the effect of labelling under-11 (U11) Swiss male youth football players (n = 24, age = 11.0 ± 0.3 years) via maturation-ordered shirt numbers during rank assessment by talent scouts (n = 83, scout experience = 4.8 ± 2.4 years). Following observation of video recorded selection tournaments, player-labelling "informed" scouts were significantly more likely to rank less mature players higher on their player potential, t(81) = 2.57, p = .012, d = -0.6, 95% CI [-1.00, -0.13], than "uninformed" scouts. As altered rankings assisted less mature players, player-labelling may offer a practical and feasible strategy to improve TID by removing possible maturation selection biases. To address maturation selection biases and the potential positive impact of player-labelling more broadly, further research on both male and female athletes in various age categories and sports contexts is recommended.



#4 Mental health symptoms and correlates among amateur football players: a cross-sectional study

Reference: Int J Environ Health Res. 2022 Aug 13;1-12. doi: 10.1080/09603123.2022.2112659. 

Authors: Yavuz Lima, Simon Rice

Summary: The objective of this study was to evaluate mental health problems reported by Turkish amateur football players. A total of 4516 Turkish amateur football players were invited to complete an anonymous online survey including demographic and COVID-19 pandemic related questions, the Patient Health Questionnaire-9, General Anxiety Disorder-7 scale, and Athlete Psychological Strain Questionnaire. A total of 1263 players participated in the study (27.9% response rate). Single players reported higher depression and anxiety scores than married players. Higher depression, anxiety, and athletes-specific stress scores were reported by players with an annual income <$5,000 and those reporting an income loss >75% during the COVID-19 pandemic. Players with a sports injury history, psychiatric illness, sleep problems, and perceived inadequate social and/or organizational support reported poorer indices relative to their counterparts. Implementation of mental health screening among amateur football players may assist in detecting vulnerabilities and initiating appropriate timely intervention.



#5 Assessing the prevalence, sources and selective antecedents of organizational stressors among elite football players and coaches in the Ghana premier league: Empirical evidence for applied practice

Reference: Front Sports Act Living. 2022 Jul 28;4:938619. doi: 10.3389/fspor.2022.938619. eCollection 2022.

Authors: Medina Srem-Sai, John Elvis Hagan Jr, Prosper Narteh Ogum, Thomas Schack

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Summary: Globally, job-related stress has been classified as a health epidemic which is common among many individuals across diverse populations. Despite this established knowledge, research has primarily focused on the general population and among health workers. Therefore, understanding stress related experiences in the context of professional sport would help design appropriate stress management interventions for effective coping. The overarching aim of this research was to assess occupational stress related experiences among players and coaches in the Ghana premier league. The study sought to assess: (1) the prevalence and sources of stressors among players and coaches, and (2) how age and years of experience influenced the stressors they experienced. Using a census survey, 44 premier league coaches and 424 players who were officially registered by 17 premier league clubs completed the intensity dimension of the Organizational Stressor Indicator for Sport Performers which has 5 subscales namely: Goals and Development, Logistics and Operations, Team and Culture, Coaching and Selection. Descriptive statistics (means and standard deviation) and multivariate analysis of variance were used to analyze the data. The results revealed that stressors were prevalent among football players and coaches, with these being significantly more dominant among coaches, p < 0.001. Selection was identified as the most predominant stressor for coaches (i.e., selecting players to play) and players (i.e., being selected). Age and experience were found not to be significant predictors of stressors for players and coaches in Ghana. Findings suggest that generally, stressors are common among football players and coaches, especially on issues related to selection. Sport psychologists and team managers in the various premier league clubs should incorporate appropriate interventions (e.g., stress inoculation training) aimed at providing adequate psychological support to promote players' and coaches' wellbeing.



#6 The reliability of lower limb 3D gait analysis variables during a change of direction to 90- and 135-degree manoeuvres in recreational soccer players

Reference: J Back Musculoskelet Rehabil. 2022 Jul 30. doi: 10.3233/BMR-210351. Online ahead of print.

Authors: Ayman Alhammad, Lee Herrington, Paul Jones, Omar Walthomali, Richard Jones

Summary: Several biomechanical outcomes are being used to monitor the risk of injuries; therefore, their reliability and measurement errors need to be known. The purpose was to measure the reliability and measurement error in lower limb 3D gait analysis outcomes during a 90∘ and 135∘ change of direction (COD) manoeuvre. A test re-test reliability study for ten healthy recreational players was conducted at seven-day intervals. Kinematics (Hip flexion, adduction, internal rotation angles and knee flexion abduction angles) and kinetics (Knee abduction moment and vertical ground reaction force) data during cutting 90∘ and 135∘ were collected using 3D gait analysis and force platform. Five trials for each task and leg were collected. Standard error of measurement (SEM) and the intraclass correlation coefficient (ICC) were calculated form the randomised leg. The ICC values of the kinematics, kinetics, and vertical ground reaction force (VGRF) outcomes (90∘ and 135∘) ranged from 0.85 to 0.95, showing good to excellent reliability. The SEM for joint angles was less than 1.69∘. The VGRV showed a higher ICC value than the other outcomes. The current study results support the use of kinematics, kinetics, and VGRF outcomes for the assessment of knee ACL risk in clinic or research. However, the hip internal rotation angle should be treated with caution since the standard measurement error exceeded 10% compared to the mean value. The measurement errors provided in the current study are valuable for future studies.



#7 How to orchestrate a soccer team: Generalized synchronization promoted by rhythmic acoustic stimuli

Reference: Front Hum Neurosci. 2022 Jul 29;16:909939. doi: 10.3389/fnhum.2022.909939. eCollection 2022.

Authors: Manfred A Müller, Antonieta Martínez-Guerrero, Maria Corsi-Cabrera, Alfred O Effenberg, Armin Friedrich, Ignacio Garcia-Madrid, Matthias Hornschuh, Gerd Schmitz, Markus F Müller

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Summary: Interpersonal coordination requires precise actions concerted in space and time in a self-organized manner. We found, using soccer teams as a testing ground, that a common timeframe provided by adequate acoustic stimuli improves the interplay between teammates. We provide quantitative evidence that the connectivity between teammates and the scoring rate of male soccer teams improve significantly when playing under the influence of an appropriate acoustic environment. Unexpectedly, female teams do not show any improvement under the same experimental conditions. We show by follow-up experiments that the acoustic rhythm modulates the attention level of the participants with a pronounced tempo preference and a marked gender difference in the preferred tempo. These results lead to a consistent explanation in terms of the dynamical system theory, nonlinear resonances, and dynamic attention theory, which may illuminate generic mechanisms of the brain dynamics and may have an impact on the design of novel training strategies in team sports.



#8 Different training sessions impact on serum protein profile of Saudi professional soccer players

Reference: Niger J Clin Pract. 2022 Aug;25(8):1287-1294. doi: 10.4103/njcp.njcp_72_22.

Authors: G O Alshuwaier, H A Ghazzawi, A I Alaqil, Y R Alsharif, A K Bursais, A T Amawi

Summary: Serum proteins serve as biomarkers for athletes and recreationally active individuals; they reflect the positive nitrogen growth balance alongside the onset of fatigue. The aim was to investigate the impact of training sessions on serum proteins is crucial to monitor their impact on athletes' future performance. A cross-sectional study to compare serum blood protein biomarker (albumin blood, blood urea nitrogen, total protein, uric acid, and creatinine), in 43 young Saudi professional soccer players in Riyadh, levels were measured pre- and post-training sessions across a 3-day period. Significant differences were found between training sessions from day 1 to day 3 in addition to the significant differences between post- and pre-training sessions with P > 0.05. Creatinine levels increased significantly in the players' blood samples post-training on all 3 days of training (P = 0.01). Albumin was the only serum protein biomarker that showed no significant changes pre- and post-training, while albumin levels varied by a statistically significant amount (P = 0.02) between pre-training (day 1 and day 2) and post-training (day 1 and day 3) periods. As biomarkers, serum proteins may provide good indicators that can be used to organize training schedules to achieve optimal outcomes. In this study, creatinine was the most sensitive biomarker measured post-training; it can be considered a critical biomarker while blood urea was the least sensitive.



#9 Extended Match Time Exacerbates Fatigue and Impacts Physiological Responses in Male Soccer Players

Reference: Med Sci Sports Exerc. 2022 Aug 12. doi: 10.1249/MSS.0000000000003021. Online ahead of print.

Authors: Magni Mohr, Georgios Ermidis, Athanasios Z Jamustas, Jeppe Vigh-Larsen, Athanasios Poulios, Dimitrios Draganidis, Konstantinos Papanikolaou, Panagiotis Tsimeas, Dimitrios Batsilas, Georgios Loules, Alexios Batrakoulis, Apostolos Sovatzidis, Jakob L Nielsen, Theofanis Tzatzakis, Charikleia K Deli, Lars Nybo, Petur Krustrup, Ioannis G Fatouros

Summary: This study evaluated how extended match time (90 + 30 min) affected physiological responses and fatigue in male soccer players. Twenty competitive players (age 21 ± 2 [±SD] years; VO2max 59 ± 4 ml/min/kg) completed an experimental match with their activity pattern and HR assessed throughout the game, while countermovement jump (CMJ) performance and repeated sprint ability (RSA) were tested and quadriceps muscle biopsies and venous blood samples taken at baseline and after 90 and 120 min of match-play. Less high-intensity running (12%) was performed in extra time in association with fewer intense accelerations and decelerations per minute compared to normal time. Peak sprint speed was 11% lower in extra time compared to normal time, and fatigue also manifested in impaired post-match RSA and CMJ performance (all p < 0.05). Muscle glycogen declined from 373 ± 59 at baseline to 266 ± 64 mmol⸱kg-1 d.w. after 90 min, with a further decline to 186 ± 56 mmol⸱kg-1 d.w. following extra time (p < 0.05) and with single fiber analyses revealing depleted or very low glycogen levels in ~75% of both slow and fast twitch fibers. Blood glucose did not change during the first 90-min but declined (p < 0.05) to 81 ± 8 mg⸱dL after extra time. Plasma glycerol and ammonia peaked at 236 ± 33 mg⸱dL and 75 ± 21 μmol⸱L after the extra period. These findings demonstrate exacerbated fatigue following extra time compared with normal time, which appears to be associated with muscle glycogen depletion, reductions in blood glucose levels and hyperammonemia. Together, this points to metabolic disturbances being a major part of the integrated and multifaceted fatigue response during extended soccer match-play.



#10 Exploring trends of running performance during matches of professional soccer players in Montenegro: A longitudinal study

Reference: Front Public Health. 2022 Aug 1;10:966578. doi: 10.3389/fpubh.2022.966578. eCollection 2022.

Authors: Kosta Goranović, Rašid Hadžić, Jovica Petković, Marko Joksimović

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Summary: The practical value of monitoring is that well-chosen performance indicators can help coaches identify the good and bad performance of individuals or teams. External monitoring of matches is useful in establishing the physiological requirements of the sport and assessing how a player compares to the requirements of the event in this regard. This study aimed to analyze the trend component of running performance during a game of professional soccer in Montenegro. The research included a sample of 82 professional soccer players. The first subsample included 44 professional soccer players of the club Budućnost from Podgorica, height 185.89 ± 6.29 cm, mass 81.06 ± 5.47 kg, BMI 23.47 ± 0.96 kg/m2, age 28.86 ± 3.85 yrs. The second subsample included 38 professional soccer players from the Sutjeska club from Nikšić, height 181.88 ± 6.35 cm, mass 77.28 ± 6.78 kg, BMI 23.32 ± 1.08 kg/m2, age 29.43 ± 5.68 yrs. The InStat kinematic system captured the outfield players by using six cameras placed around the perimeter of the field at the minimal height of 12 m. The frame frequency was 25 frames per second; data were centralized for further analysis. Statistically significant differences were noted only in the variable sprint distance in the 2017 season. The results of the current research indicate that the soccer players who compete in Montenegro are below the values achieved by those who compete in Europe.



#11 A multi-club analysis of the locomotor training characteristics of elite female soccer players

Reference: Sci Med Footb. 2022 Aug 18. doi: 10.1080/24733938.2022.2114603. Online ahead of print.

Authors: Naomi Myhill, Dan Weaving, Steve Barrett, Ryan King, Stacey Emmonds

Summary: The objective was to quantifying differences in locomotor characteristics of training between two competition levels and between training days within elite female soccer players. Foot-mounted inertial measurement unit (Playermaker) data were collected from 293 players from three Women's Super League (WSL; n = 76) and eight Women's Championship (WC; n = 217) teams over a 28-week period. Data were analysed using partial least squares correlation analysis to identify relative variable importance and linear mixed effects models to identify magnitude of effects. WSL players performed more high-speed running distance (HSR; >5.29m∙s-1), sprint distance (SpD; >6.26m∙s-1), acceleration (ACC; >3m∙s-2) and deceleration (DEC; <-3m∙s-2) distance than WC players. The largest difference between WSL and WC in HSR and HSR per minute occurred on MD-4, (354.7 vs. 190.29 m and 2.8 vs. 1.7 m∙min-1). On MD-2, WSL players also covered greater SpD (44.66 vs. 12.42 m), SpD per minute (0.38 vs. 0.11 m∙min-1) and HSR per minute (1.67 vs. 0.93 m∙min-1). Between training days both WSL and WC teams reduced HSR and SpD but not ACC and DEC distance from MD-4 to MD-2, with MD-4 the highest training day of the week. MD-4 is a key training day discriminating between competitive level. HSR and SpD volume and intensity is tapered in WSL and WC players, however there is less clear taper of ACC or DEC. As such, WC teams could increase the volume and intensity of HSR on MD-4 to mimic locomotor activities of those at a higher standard.



#12 Effectiveness of wearable technology to optimize youth soccer players' off-training behaviour and training responses: a cluster-randomized trial

Reference: Sci Med Footb. 2022 Aug 25;1-9. doi: 10.1080/24733938.2022.2114604. Online ahead of print.

Authors: Nuno Mateus, Juliana Exel, Sara Santos, Bruno Gonçalves, Jaime Sampaio

Summary: A cluster-randomized trial examined the effect of activity wristbands on young players' off-training PA and SB profiles; assessed the added value of wearable wristbands with PA warnings; and investigated whether manipulating off-training PA can affect the players' training responses. Thirty-two adolescent soccer players (16.1 ± 0.9 years old) were monitored during weekdays for two weeks (interspersed with one week). Players were randomly assigned to a reminder to move (REM) and a non-reminder to move group (nREM). The REM wore an activity wristband (Fitbit Charge 2) with PA warnings in the last week of research, while the nREM wore identical monitors without PA feedback. Throughout the study, off-training PA was assessed using tri-axial accelerometers, and training responses were analysed using wearable inertial monitoring units. Gardner-Altman estimation plots and a Fisher's Exact Test of Independence estimated each group's off-training PA changes between the monitored weeks. Complementary, an analysis of covariance identified the effect of the activity wristband configuration (REM vs nREM) on players' off-training PA profiles and soccer training responses. Interestingly, results showed that different wearable wristbands did not influence the players' off-training PA profiles (p > 0.05). Concomitantly, no differences were observed in training responses (p > 0.05). Findings emphasize the importance of health and youth sports organizations in developing newer approaches for promoting healthier lifestyles, beyond training practices, with potentially favourable implications for sports performance.



#13 Associations between biological maturity level, match locomotion, and physical capacities in youth male soccer players

Reference: Scand J Med Sci Sports. 2022 Aug 25. doi: 10.1111/sms.14225. Online ahead of print.

Authors: Hilde Gundersen, Amund Riiser, Erling Algroy, Mona Vestbøstad, Atle H Saeterbakken, Hege Havstad Clemm, Halvard Grendstad, Arild Hafstad, Morten Kristoffersen, Cecilie Brekke Rygh

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Summary: Biological maturity level has shown to affect sport performance in youths. However, most previous studies have used noninvasive methods to estimate maturity level. Thus, the main aim of the present study was to investigate the association between skeletal age (SA) as a measure of biological maturation level, match locomotion, and physical capacity in male youth soccer players. Thirty-eight Norwegian players were followed during two consecutive seasons (U14 and U15). Match locomotion was assessed with GPS-tracking in matches. SA, assessed by x-ray, physical capacities (speed, strength and endurance) and anthropometrics were measured in the middle of each season. Analysis of associations between SA, match locomotion, and physical capacities were adjusted for the potential confounding effect of body height and weight. In matches, positive associations were found between SA and maximal speed and running distance in the highest speed zones. Further, SA was associated with 40 m sprint time and countermovement jump (CMJ) height, and with intermittent-endurance capacity after adjusting for body height (U14). Associations between SA and leg strength and power, and between SA and absolute VO2max were not significant after adjusting for body weight. There was no association between SA and total distance covered in matches. Biological maturity level influence match locomotion and performance on physical capacity tests. It is important that players, parents and coaches are aware of the advantages more mature players have during puberty, and that less mature players also are given attention, appropriate training and match competition to ensure proper development.



#14 Breaking new grounds in injury risk screening in soccer by deploying unsupervised learning with a special focus on sex and fatigue effects

Reference: Sports Biomech. 2022 Aug 24;1-17. doi: 10.1080/14763141.2022.2112748. Online ahead of print.

Authors: Gerda Strutzenberger, Sina David, Lana Mei Borcard, Stefan Fröhlich, Florian B Imhoff, Johannes Scherr, Jörg Spörri

Summary: In injury prevention, a vertical drop jump (DJ) is often used for screening athletes at risk for injury; however, the large variation in individual movement patterns might mask potentially relevant strategies when analysed on a group-based level. Two movement strategies are commonly discussed as predisposing athletes to ACL injuries: a deficient leg axis and increased leg stiffness during landing. This study investigated the individual movement pattern of 39 female and male competitive soccer players performing DJs at rest and after being fatigued. The joint angles were used to train a Kohonen self-organising map. Out of 19,596 input vectors, the SOM identified 700 unique postures. Visualising the movement trajectories and adding the latent parameters contact time, medial knee displacement (MKD) and knee abduction moment allow identification of zones with presumably increased injury risk and whether the individual movement patterns pass these zones. This information can be used, e.g., for individual screening and for feedback purposes. Additionally, an athlete's reaction to fatigue can be explored by comparing the rested and fatigued movement trajectories. The results highlight the ability of unsupervised learning to visualise movement patterns and to give further insight into an individual athlete's status without the necessity of a priori assumptions.



#15 Does biologically categorised training alter the perceived exertion and neurmuscular movement profile of academy soccer players compared to traditional age-group categorisation?

Reference: Eur J Sport Sci. 2022 Aug 23;1-12. doi: 10.1080/17461391.2022.2117090. Online ahead of print.

Authors: Jamie Salter, James Black, James Mallett, Steve Barrett, Christopher Towlson, Jonathan D Hughes, Mark De St Croix

Summary: The individual response to load is multifactorial and complicated by transient and temporal changes in biological maturation. The period surrounding peak height velocity exposes potentially 'fragile' individuals to systematic, age-related increases in training loads. Bio-banding allows practitioners to manage the biological diversity and align training to the development needs to each athlete. This study explores the acute impact of maturation on neuromuscular performance and perceived intensity through comparing both chronological and bio-banded training sessions.55 male soccer players (mean ±SD; age 13.8 ±1.4 years) were recruited from an EPPP academy. Following a warm-up and standardised sub-maximal run (30-15IFT), players competed in five bouts of 5-minute 6v6 small-sided games (SSGs) before repeating the standardised sub-maximal run. The sessions were repeated on three occasions with chronological SSGs and the same with bio-banded SSGs wearing foot-mounted inertial measurement units (PlayerMakerTM) with differential ratings of perceived exertion used to quantify internal loads.Mixed linear modelling indicated maturity-specific pre-post differences in neuromuscular response, stride length and cadence having contrasting responses pre- (reduced) and post-PHV (increased), and larger changes in post sessions stiffness for pre- (∼18.6 kN·m-1) and circa-PHV (∼12.1 kN·m-1) players. Secondly, there were small to large differences in neuromuscular response (RSI stride length, stiffness, and contact time) and perceptions of intensity between chronological and bio-banded sessions, with bio-banding generally reducing pre-post changes.Bio-banding may offer a mechanism to prescribe maturity-specific training loads which may help to alleviate the impact of repeated exposure to high-intensity activity, thus reducing injury risk whilst promoting long-term player development.



#16 Return to Sport Soccer after Anterior Cruciate Ligament Reconstruction: ISAKOS Consensus

Reference: J ISAKOS. 2022 Aug 20;S2059-7754(22)00079-7. doi: 10.1016/j.jisako.2022.08.004.

Authors: David Figueroa, Guillermo Arce, M Joao Espregueira, Rodrigo Maestu, Manuel Mosquera, Andy Williams, David Parker, Moises Cohen, Mustafa Karahan, Germán Alberto Ochoa Perea, Stefano Zaffagnini, Philippe Neyret, Jon Karlsson, Volker Musahl, Fernando Radice, Willem M van der Merwe, Philippe Landreau, Andreas Imhoff, Jacques Menetrey, Olufemi R Ayeni, Gustavo Gonçalves Arliani, Seth Lawrence Sherman, Joan C Monllau, Pieter D'Hooghe, Leo Pinczewski, Julian Feller, Sartha Patnaik

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Summary: Many factors can affect the return to pivoting sports, after an Anterior Cruciate Ligament Reconstruction. Prehabilitation, rehabilitation, surgical and psychological aspects, plays an essential role in the decision to return to sports. The purpose of this study is to reach an international consensus about the best conditions for returning to sports in soccer - one of the most demanding level I pivoting sports after ACL reconstruction. 34 International experts in the management of ACL injuries, representing all the Continents were convened and participated in a process based on the Delphi method to achieve a consensus. 37 statements related to ACL reconstruction were reviewed by the experts in three rounds of surveys in complete anonymity. The statements were prepared by the working group based on previous literature or systematic reviews. Rating agreement through a Likert Scale: strongly agree, agree, neither agree or disagree, disagree, and strongly disagree was used. To define consensus, it was established that the assertions should achieve a 75% of agreement or disagreement. Of the 37 statements, 10 achieved unanimous consensus, 18 non-unanimous consensus and 9 did not achieve consensus. In the preoperative, the correction of the ROM deficit, the previous high level of participation in sports, and a better knowledge of the injury by the patient and compliance to participate in Rehabilitation were the statements that reached unanimous consensus.During the surgery, the treatment of associated injuries, as well as the use of autografts, and the addition of a lateral extra-articular tenodesis in some particular cases (active young athletes, <25 years old, hyperlaxity, high rotatory laxity and revision cases) obtained also 100% consensus. In the postoperative period, psychological readiness, and its validation with scales, adequate physical preparation, as well as not basing the RTSS purely on the time of evolution after surgery, were the factors that reached unanimous Consensus. The consensus statements derived from this international ISAKOS leaders, may assist clinicians in deciding when to return to sports soccer in patients after an ACL reconstruction. Those statements that reached 100% consensus have to be strongly considered in the final decision to RTS soccer.



#17 Skeletal age assessed by TW2 using 20-bone, carpal and RUS score systems: Intra-observer and inter-observer agreement among male pubertal soccer players

Reference: PLoS One. 2022 Aug 23;17(8):e0271386. doi: 10.1371/journal.pone.0271386. eCollection 2022.

Authors: Paulo Sousa-E-Silva, Manuel J Coelho-E-Silva, Andre Seabra, Daniela C Costa, Diogo V Martinho, João P Duarte, Tomás Oliveira, João Gonçalves-Santos, Inês Rodrigues, Luis P Ribeiro, António J Figueiredo, Jan M Konarski, Sean P Cumming, Robert M Malina

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Summary: The purpose of this study was to determine intra- and inter-observer agreement for the three skeletal ages derived from the TW2 method among male pubertal soccer players. The sample included 142 participants aged 11.0-15.3 years. Films of the left hand-wrist were evaluated twice by each of two observers. Twenty bones were rated and three scoring systems used to determine SA adopting the TW2 version: 20-bone, CARPAL and RUS. Overall agreement rates were 95.1% and 93.8% for, respectively, Observer A and Observer B. Although, agreement rates between observers differed for 13 bones (5 carpals, metacarpal-I, metacarpal-III, metacarpal-V, proximal phalanges-I, III and V, distal phalanx-III), intra-class correlationa were as follows: 0.990 (20-bone), 0.969 (CARPAL), and 0.988 (RUS). For the three SA protocols, BIAS was negligible: 0.02 years (20-bone), 0.04 years (CARPAL), and 0.03 years (RUS). Observer-associated error was not significant for 20-bone SA (TEM = 0.25 years, %CV = 1.86) neither RUS SA (TEM = 0.31 years, %CV = 2.22). Although the mean difference for CARPAL SAs between observers (observer A: 12.48±1.18 years; observer B: 12.29±1.24 years; t = 4.662, p<0.01), the inter-observer disagreement had little impact (TEM: 0.34 years: %CV: 2.78). The concordance between bone-specific developmental stages seemed was somewhat more problematic for the carpals than for the long bones. Finally, when error due to the observer is not greater than one stage and the replicated assignments had equal probability for being lower or higher compared to initial assignments, the effect on SAs was trivial or small.



#18 Effect of Exercise Intensity on Psychomotor Vigilance During an Incremental Endurance Exercise in Under-19 Soccer Players

Reference: Motor Control. 2022 Aug 25;1-16. doi: 10.1123/mc.2022-0033. Online ahead of print.

Authors: Francisco Tomás González-Fernández, Pedro Ángel Latorre-Román, Juan Parraga-Montilla, Alfonso Castillo-Rodriguez, Filipe Manuel Clemente

Summary: The aim of this study was to analyze the acute effects of an incremental resistance test on psychomotor vigilance in 16 soccer players under-19 years old (age 16.42 ± 0.85 years). Borg 15-point subjective perception of effort scale, the psychomotor vigilance task test, and the Yo-Yo intermittent recovery test were used. Four evaluation sessions were conducted with different intensities of efforts (30%-40%, 60%-75%, 80%-90%, and 100%) on different days (counterbalanced order). A repeated-measures analysis of variance was performed in the reaction time of the psychomotor vigilance task. The results showed that participants responded faster during efforts between 80% and 90% of maximal oxygen uptake (501.20 ± 70.77 ms). From that threshold, the players decreased their performance through a longer reaction time (601.23 ± 85.05 ms; p value < .001). The main findings were that the reaction time performance was worse at the lowest and highest effort conditions (5 and 17 km/hr, respectively). This fact helps to focus on the importance of designing and proposing training tasks with medium-high efforts to provoke optimal reaction times in young soccer players.



#19 Analyzing the within and between Players Variability of Heart Rate and Locomotor Responses in Small-Sided Soccer Games Performed Repeatedly over a Week

Reference: Healthcare (Basel). 2022 Jul 28;10(8):1412. doi: 10.3390/healthcare10081412.

Authors: Ana Filipa Silva, Francisco Tomás González-Fernández, Rodrigo Aquino, Zeki Akyildiz, Luiz Palucci Vieira, Mehmet Yıldız, Sabri Birlik, Hadi Nobari, Gibson Praça, Filipe Manuel Clemente

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Summary: Small-sided games (SSGs) are drill-based and constrained exercises designed to promote a technical/tactical and physiological/physical stimulus on players while preserving some dynamics of the real game. However, as a dynamic game, they can offer some variability making the prediction of the stimulus hardest for the coach. The purpose of this study was to analyze the between-session and within-player variability of heart rates and locomotor responses of young male soccer players in 3v3 and 5v5 small-sided game formats. This study followed a repeated-measures study design. Twenty soccer players were enrolled in a study design in which the SSG formats 3v3 and 5v5 were performed consecutively across four days. Twenty under-17 male youth soccer players (16.8 ± 0.4 years old) voluntarily participated in this study. Participants were monitored using a Polar Team Pro for measuring the heart rate mean and maximum, distances covered at different speed thresholds, and peak speed. Between-players variability revealed that maximum heart rate was the outcome with a smaller coefficient of variation (3v3 format: 3.1% to 11.1%; 5v5 format: 6.6% to 15.2%), while the distance covered at Z5 (3v3 format: 82.5% to 289.8%; 5v5 format: 94.0% to 221.1%). The repeated measures ANOVA revealed that the four games tested were different in the within-player variability considering the maximum heart rate (p = 0.032), total distance (p &lt; 0.001), and distances at zone 1, 2, and 5 of speed (p &lt; 0.001). The smaller small-sided game tested promotes greater within-player variability in locomotor demands while promoting smaller within-player variability heart rate responses. Possibly, 5v5 is more recommended to stabilize the locomotor demands, while the 3v3 is recommended to stabilize the heart rate stimulus.



#20 COVID-19 in European Soccer: A Public 2-Year Comparison of COVID-19 Case Management and Case Characteristics between the 1st Bundesliga, La Liga, Serie A and the Premier League

Reference: Life (Basel). 2022 Aug 11;12(8):1220. doi: 10.3390/life12081220.

Authors: Jan-Niklas Droste, Robert Percy Marshall, Stephan Borte, Sebastian Seyler, Helge Riepenhof

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Summary: To evaluate the extent and characteristics of COVID-19 cases in relation to environmental COVID-19 incidences in the four best European soccer leagues (Bundesliga, Premier League, Serie A and La Liga) from the first of January 2020 until the end of January 2022. A retrospective evaluation of all publicly available COVID-19 cases in the studied cohorts was performed. The 14-day case incidences from epidemiological national data were used as reference values. The leagues studied are the Bundesliga (Germany), Premier League (Great Britain), Serie A (Italy) and La Liga (Spain). For all cases, the duration of time loss and date of case notification were recorded. League-specific mean time loss due to disease or quarantine per COVID-19 case differs significantly between La Liga (11.45; ±5.21 days) and the other leagues studied (Bundesliga 20.41; ±33.87; p 0.0242; Premier League 17.12; ±10.39; p 0.0001; Serie A 17.61; ±12.71; p &lt; 0.0001). A positive correlation between 14-day national incidence with COVID-19 disease occurrence in soccer leagues was found for all leagues studied. The correlations were strong in the Bundesliga (r 0.5911; CI 0.4249-0.7187; p &lt; 0.0001), Serie A (r 0.5979; CI 0.4336-0.7238; p &lt; 0.0001) and La Liga (r 0.5251; CI 0.3432-0.6690; p &lt; 0.0001). A moderate correlation was found for the Premier League (r 0.3308; CI 0.1147-0.5169; p 0.0026). Odds ratios for altered environmental case risk in the cohorts studied could be calculated for four different national COVID-19 incidence levels (&lt;50/100.000 to &gt;500/100.000). A trend towards shorter COVID-19 case duration in the second half of 2021 was shown for all leagues studied. There was a significantly lower mean time-loss caused by a COVID-19 infection for cases occurred in La Liga compared with the other three leagues studied. For all four leagues studied, a positive, significant correlation of national environmental COVID-19 incidence level and the incidence of COVID-19 cases in the cohort of a football league was found.


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