Latest research in football - week 4 - 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 Variations of the Locomotor Profile, Sprinting, Change-of-Direction, and Jumping Performances in Youth Soccer Players: Interactions between Playing Positions and Age-Groups

Reference: Int J Environ Res Public Health. 2022 Jan 17;19(2):998. doi: 10.3390/ijerph19020998.

Authors: Ana Filipa Silva, Sümer Alvurdu, Zeki Akyildiz, Georgian Badicu, Gianpiero Greco, Filipe Manuel Clemente

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Summary: The purpose of this study was two-fold: (i) analyze the variations of locomotor profile, sprinting, change-of-direction (COD) and jumping performances between different youth age-groups; and (ii) test the interaction effect of athletic performance with playing positions. A cross-sectional study design was followed. A total of 124 youth soccer players from five age-groups were analyzed once in a time. Players were classified based on their typical playing position. The following measures were obtained: (i) body composition (fat mass); (ii) jump height (measured in the countermovement jump; CMJ); (iii) sprinting time at 5-, 10-, 15-, 20-, 25- and 30-m; (iv) maximal sprint speed (measured in the best split time; MSS); (v) COD asymmetry index percentage); (vi) final velocity at 30-15 Intermittent Fitness Test (VIFT); and (vii) anaerobic speed reserve (ASR = MSS - VIFT). A two-way ANOVA was used for establishing the interactions between age-groups and playing positions. Significant differences were found between age-groups in CMJ (p < 0.001), 5-m (p < 0.001), 10-m (p < 0.001), 15-m (p < 0.001), 20-m (p < 0.001), 25-m (p < 0.001), 30-m (p < 0.001), VIFT (p < 0.001), ASR (p = 0.003), MSS (p < 0.001), COD (p < 0.001). Regarding variations between playing positions no significant differences were found. In conclusion, it was found that the main factor influencing changes in physical fitness was the age group while playing positions had no influence on the variations in the assessed parameters. In particular, as older the age group, as better was in jumping, sprinting, COD, and locomotor profile.



#2 Comparison of the Cardiovascular Effects of Extreme Psychological and Physical Stress Tests in Male Soccer Players

Reference: Int J Environ Res Public Health. 2022 Jan 9;19(2):715. doi: 10.3390/ijerph19020715.

Authors: Ákos Móra, Zsolt Komka, József Végh, István Farkas, Gyöngyi Szilágyi Kocsisné, Edit Bosnyák, Márta Szmodis, Roland Ligetvári, Éva Csöndör, Gábor Almási, András Oláh, Han C G Kemper, Miklós Tóth, Pongrác Ács

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Summary: The purpose of our study was to compare the physiological effects of extreme physical and psychological stress tests in male soccer players, since these two types of stress apply to athletes with high performance requirements. A total of 63 healthy male soccer players participated in this study, all of whom underwent both of the tests. A physical stress test was carried out in an exercise physiology laboratory, where subjects completed an incremental treadmill running test to full exhaustion, and a psychological test was performed in a military tactical room, where subjects met a street offence situation. Heart rate variability (HRV) and blood pressure (BP) were recorded directly before, immediately after, and 30 min after the stress tests. The majority of HRV indices changed significantly in both stress protocols. Inverse, significant changes (positive for the physical test, negative for the psychological test, p < 0.001) were found when comparing the alterations of HRV indices between the tests. Significant differences were found in the changes in systolic (p = 0.003) and diastolic (p < 0.001) BP between the test protocols, and also between the baseline and post-test measurements (p < 0.001). Both HRV and BP are sensitive physiological parameters to measure the impact of extreme physical and/or psychological stress.



#3 Relationship between Isokinetic Knee Strength and Speed, Agility, and Explosive Power in Elite Soccer Players

Reference: Int J Environ Res Public Health. 2022 Jan 7;19(2):671. doi: 10.3390/ijerph19020671.

Authors: Jaroslaw Kabacinski, Piotr M Szozda, Krzysztof Mackala, Michal Murawa, Agata Rzepnicka, Piotr Szewczyk, Lechoslaw B Dworak

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Summary: The aim of this study was to determine the relationship between the isokinetic characteristics of knee extensors and flexors with selected motor abilities: Speed, agility, and explosive power of lower extremities of professional football players in the preparation period of a yearly training cycle. Twenty-one players (age: 24.5 ± 3.9 years; body mass: 76.7 ± 4.7 kg and body height: 183.5 ± 5.5 cm) playing in the highest Polish soccer league participated in the study. The isokinetic concentric torque of the knee extensors and flexors was measured at 300°/s, 180°/s, and 60°/s velocities. Sprint performance was assessed in the 30 m sprint test (standing start). The forward, lateral, and backward movements were assessed using the T-Test of agility. Explosive power was quantified by performing the squat jump (SJ) and countermovement (CMJ), using the force platform. Due to sport-specific demands of soccer activities measured in this experiment, the relationships between peak torque (PT) and the 30 m sprint, T-Test of agility, and power of vertical jumps (SJ and CMJ) were low or medium at speeds of 60°/s and 300°/s. One of the main reasons for the lack of high dependence of the above-mentioned factors are that the measurements were performed during the initial training period where the level of individual abilities is at a low level. Additionally, this experiment may also indicate that the measurement of isokinetic knee flexion and extension peak is effective when performed at the correct angular velocity in relation to the evaluation of the intended motion structure.



#4 Knee Flexor Eccentric Strength, Hamstring Muscle Volume and Sprinting in Elite Professional Soccer Players with a Prior Strained Hamstring

Reference: Biology (Basel). 2022 Jan 3;11(1):69. doi: 10.3390/biology11010069.

Authors: Alberto Mendez-Villanueva, Francisco Javier Nuñez, Jose Luis Lazaro-Ramirez, Pablo Rodriguez-Sanchez, Marc Guitart, Gil Rodas, Imanol Martin-Garetxana, Josean Lekue, Valter Di Salvo, Luis Suarez-Arrones

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Summary: The aim was to determine if players with a prior hamstring strain injury (HSI) exhibit bilateral deficits in knee flexor eccentric strength and hamstring muscle volume and differences in sprinting performance compared with players without a history of HSIs. Forty-six male professional soccer players participated in this study. Eccentric knee flexor strength, hamstring muscle volume (MRI), and a 20-m running sprint test (5- and 10-m split time) were assessed at the start of the preseason. Eccentric knee strength of the previously injured limbs of injured players was greater (ES: 1.18-1.36) than the uninjured limbs in uninjured players. Previously injured limbs showed possibly larger biceps femoris short heads (BFSh) and likely semitendinosus (ST) muscle volumes than the contralateral uninjured limbs among the injured players (ES: 0.36) and the limbs of the uninjured players (ES: 0.56), respectively. Players who had experienced a previous HSI were possibly slower in the 5-m (small ES: 0.46), while unclear differences were found in both the 10-m and 20-m times. Players with a prior HSI displayed greater eccentric knee flexor strength, possibly relatively hypertrophied ST and BFSh muscles, and possibly reduced 5-m sprinting performances than previously uninjured players. This can have implication for the design of secondary hamstring muscle injury prevention strategies.



#5 Physical Fitness and Performance in Talented & Untalented Young Chinese Soccer Players

Reference: Healthcare (Basel). 2022 Jan 4;10(1):98. doi: 10.3390/healthcare10010098.

Authors: Alfredo Irurtia, Víctor M Torres-Mestre, Álex Cebrián-Ponce, Marta Carrasco-Marginet, Albert Altarriba-Bartés, Marc Vives-Usón, Francesc Cos, Jorge Castizo-Olier

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Summary: Sports performance is a complex process that involves many factors, including ethnic and racial differences. China's youth soccer is in a process of constant development, although information about the characteristics of its players and their methodological systems is scarce. The aim of this retrospective study was to characterize the physical fitness and the competitive performance of 722 Chinese players of three sports categories (8.0-9.9, 10.0-11.9 and 12.0-13.9 years), who were classified by their coaches as talented (n = 204) or untalented (n = 518). Players were assessed for anthropometry (body height, body mass, body mass index), lung capacity (Forced Vital Capacity), jumping performance (Squat Jump, Countermovement Jump and Abalakov tests), sprinting performance (10 m and 30 m Sprint tests), agility performance (Repeated Side-Step test) and flexibility (Sit & Reach test). A descriptive, comparative, correlational and multivariate analysis was performed. Competitive ranking was created in order to act as dependent variable in multiple linear regression analysis. Results indicate that Chinese players classified as talented have better motor performance than untalented ones. However, these differences are neither related nor determine the competitive performance of one group or the other.



#6 Undiagnosed apical hypertrophic cardiomyopathy in an old amateur soccer player: a case report

Reference: Pan Afr Med J. 2021 Nov 25;40:182. doi: 10.11604/pamj.2021.40.182.28588. eCollection 2021.

Authors: Mahassine El Harras, Ilham Bensahi, Salma Abdeladim, Fatimazahra Merzouk, Amal Elouarradi, Sara Oualim, Mohamed Sabry

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Summary: Hypertrophic cardiomyopathy is a primary muscle disorder characterized by an abnormal thickness of the left ventricular wall. It is often going undiagnosed because many patients have few symptoms and can lead normal lives. This is a case report about an apical cardiomyopathy diagnosed at a very late stage in an old amateur soccer player. He was hospitalized due to acute chest pain; neurologic disorder related to a hypertensive emergency, he underwent successful percutaneous coronary intervention, echocardiography and CMR revealed Apical hypertrophic cardiomyopathy. The development of sports cardiology has major importance in the detection of cardiac disease which may have poor prognosis. Our patient had the chance to achieve his entire career without rhythmic complications.



#7 Measurement properties of external training load variables during standardised games in soccer: Implications for training and monitoring strategies

Reference: PLoS One. 2022 Jan 21;17(1):e0262274. doi: 10.1371/journal.pone.0262274. eCollection 2022.

Authors: Jo Clubb, Chris Towlson, Steve Barrett

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Summary: The aim of this study was to assess the measurement properties of external training load measures across three formats of standardised training games. Eighty-eight players from two English professional soccer clubs participated in the study spanning three consecutive seasons. External training load data was collected from three types of standardised game format drills (11v11, 10v10, 7v7+6) using Global Positioning Systems. For each external training load metric in each game format, the following measurement properties were calculated; coefficient of variation (CV%) to determine between- and within-subject reliability, intraclass coefficient correlation (ICC) to determine test-retest reliability, and signal-to-noise ratio (SNR) to determine sensitivity. Total distance (TD) and PlayerLoad™ (PL) demonstrated good sensitivity (TD SNR = 1.6-4.6; PL SNR = 1.2-4.3) on a group level. However, a wide variety of within-subject reliability was demonstrated for these variables (TD CV% = 1.7-36.3%; PL CV% = 4.3-39.5%) and corresponding intensity measures calculated per minute. The percentage contribution of individual planes to PL showed the lowest between-subject CV% (CV% = 2-7%), although sensitivity varied across formats (SNR = 0.3-1.4). High speed running demonstrated poor reliability across all three formats of SSG (CV% = 51-103%, ICC = 0.03-0.53). Given the measurement properties of external training load measures observed in this study, specifically the within-subject variation, reliability across trials of standardised training games should be calculated on an individual level. This will allow practitioners to detect worthwhile changes across trials of standardised game format drills. Such information is important for the appropriate implementation of training and monitoring strategies in soccer.



#8 Context is key: normalization as a novel approach to sport specific preprocessing of KPI's for match analysis in soccer

Reference: Sci Rep. 2022 Jan 21;12(1):1117. doi: 10.1038/s41598-022-05089-y.

Authors: Ashwin A Phatak, Saumya Mehta, Franz-Georg Wieland, Mikael Jamil, Mark Connor, Manuel Bassek, Daniel Memmert

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Summary: Key Performance Indicators (KPIs) have been investigated, validated and applied in multitude of sports for recruiting, coaching, opponent, self-analysis etc. Although a wide variety of in game performance indicators have been used as KPIs, they lack sports specific context. With the introduction of artificial intelligence and machine learning (AI/ML) in sports, the need for building intrinsic context into the independent variables is even greater as AI/ML models seem to perform better in terms of predictability but lack interpretability. The study proposes domain specific feature preprocessing method (normalization) that can be utilized across a wide range of sports and demonstrates its value through a specific data transformation by using team possession as a normalizing factor while analyzing defensive performance in soccer. The study performed two linear regressions and three gradient boosting machine models to demonstrate the value of normalization while predicting defensive performance. The results demonstrate that the direction of correlation of the relevant variables changes post normalization while predicting defensive performance of teams for the whole season. Both raw and normalized KPIs showing significant correlation with defensive performance (p < 0.001). The addition of the normalized variables contributes towards higher information gain, improved performance and increased interpretability of the models.



#9 A musculoskeletal modelling approach of the assessment of the risk of hamstring injuries in professional soccer players: a pilot study

Reference: Sci Med Footb. 2021 Feb;5(1):55-58. doi: 10.1080/24733938.2020.1786765. Epub 2020 Jun 28.

Authors: Mathieu Ménard, Anthony Sorel, Rufin Boumpoutou, Richard Kulpa, Hugo A Kerhervé, Benoit Bideau

Summary: Evaluating and minimising the risk of hamstring injury remains complex as it lacks reliable field-testing. Kinematic analysis provides global external insights but fails to apprehend musculoskeletal loading. This study aimed to evaluate the association between hamstring function and prior injury using a novel functional test combined with a musculoskeletal approach. Twelve professional footballers, distributed in two groups (control or previously injured), performed a reactive functional test to one of four targets from a standing start and performed a knee and plantar extension on target. Joint kinematics served as input data of a musculoskeletal model, and joint angles and hamstring muscle lengths were calculated. Biceps femoris long head (BFlh) was stretched to 150 ± 2% of initial length during the two conditions. Maximal BFlh length and time to stretch were significantly higher in the control group. Kinematics and musculoskeletal parameters revealed that participants of the control group had higher maximal hip flexion, pelvis anterior tilt, and hip internal rotation than previously injured players. The combined approach of a hamstring functional test and musculoskeletal modelling gives new preliminary insights on the effect of previous history of hamstring injury on lower limb kinematics and BFlh muscle length.



#10 Physiological characteristics and acute fatigue associated with position-specific speed endurance soccer drills: production vs maintenance training

Reference: Sci Med Footb. 2021 Feb;5(1):6-17. doi: 10.1080/24733938.2020.1789202. Epub 2020 Jul 21.

Authors: Jack D Ade, Barry Drust, Oliver J Morgan, Paul S Bradley 

Summary: The study aimed to compare the physiological characteristics and acute fatigue associated with position-specific speed endurance production (SEP) and maintenance (SEM) soccer drills. Twenty male soccer players performed a position specific drill consisting of 8 exercise bouts each lasting ~30 s interspersed by 150 s (SEP) and 60 s (SEM) of passive recovery. A selection of players (n = 10) completed neuromuscular assessments pre and post drill. Players covered greater high speed (12%), very high speed (49%) and sprint (218%) running distances in SEP (P < 0.05, ES: 0.51-0.80). SEP resulted in greater peak (7%) and average (10%) running speeds (P < 0.01, ES: 0.70-0.93). Mean and peak heart rate responses were greater in SEM (4-10%, P < 0.01, ES: 0.97-1.84) whilst blood lactate concentrations were higher following SEP (6%, P < 0.05, ES: 0.42). Reductions in vertical countermovement jump height were more pronounced immediately after SEP (2%, P < 0.05, ES: 0.36) but 24 h post SEM (4%, P < 0.05, ES: 0.52). Horizontal countermovement jump performance was reduced immediately post SEP and SEM (3-5%, P < 0.01, ES: 0.22-0.38) and 24 h post SEM (4%, ES: 0.32). The data demonstrate that position-specific SEP and SEM drills overload different physiological indices and induce small impairments in some neuromuscular measures.



#11 Feedback of GPS training data within professional English soccer: a comparison of decision making and perceptions between coaches, players and performance staff

Reference: Sci Med Footb. 2021 Feb;5(1):35-47. doi: 10.1080/24733938.2020.1770320. Epub 2020 Jun 14.

Authors: Perry Nosek, Thomas E Brownlee, Barry Drust, Matthew Andrew

Summary: The aim of the study was to examine the perceptions of training data feedback from key stakeholders within the coaching process of professional soccer clubs. A survey assessed the importance of training data towards reflection and decision-making, potential barriers and player preferences. A total of 176 participants comprising coaches, players and performance staff completed the survey. The training data coaches most commonly identified as wanting to see to support reflection was 'high-intensity' actions and variables recognised by the coach as 'work rate/intensity'. All stake- holders reported training data as at least somewhat important in guiding their coaches' practices, with lack of a common goal and high volumes of information being the main barriers to effective feedback of training data. Players deemed feedback as positive to change their behaviour, with total distance, high-speed running and sprint distances as the information they would most like to see. It would be likely to be looked at via message or pinned up in the changing room. Training data are seen as an impactful and effective tool for use by all key stakeholders. Despite this, its use can be optimised by increasing opportunities for informal reflection, using less information, and improving communication of data.



#12 Seasonal Accumulated Workloads in Collegiate Women's Soccer: A Comparison of Starters and Reserves

Reference: J Funct Morphol Kinesiol. 2022 Jan 16;7(1):11. doi: 10.3390/jfmk7010011.

Authors: Andrew R Jagim, Andrew T Askow, Victoria Carvalho, Jason Murphy, Joel A Luedke, Jacob L Erickson

Summary: Research quantifying the unique workload demands of starters and reserves in training and match settings throughout a season in collegiate soccer is limited.  The purpose of the current study is to compare accumulated workloads between starters and reserves in collegiate soccer.  Twenty-two NCAA Division III female soccer athletes (height: 1.67 ± 0.05 m; body mass: 65.42 ± 6.33 kg; fat-free mass: 48.99 ± 3.81 kg; body fat %: 25.22 ± 4.78%) were equipped with wearable global positioning systems with on-board inertial sensors, which assessed a proprietary training load metric and distance covered for each practice and 22 matches throughout an entire season. Nine players were classified as starters (S), defined as those playing >50% of playing time throughout the entire season. The remaining 17 were reserves (R). Goalkeepers were excluded. A one-way ANOVA was used to determine the extent of differences in accumulated training load throughout the season by player status.  Accumulated training load and total distance covered for starters were greater than reserves ((S: 9431 ± 1471 vs. R: 6310 ± 2263 AU; p < 0.001) and (S: 401.7 ± 31.9 vs. R: 272.9 ± 51.4 km; p < 0.001), respectively) throughout the season.  Starters covered a much greater distance throughout the season, resulting in almost double the training load compared to reserves. It is unknown if the high workloads experienced by starters or the low workloads of the reserves is more problematic. Managing player workloads in soccer may require attention to address potential imbalances that emerge between starters and reserves throughout a season.



#13 The effect of fatigue on first stance phase kinetics during acceleration sprint running in professional football players

Reference: Sci Med Footb. 2021 May;5(2):90-96.  doi: 10.1080/24733938.2020.1799064. Epub 2020 Jul 30.

Authors: Maximilian M Wdowski, Neil Clarke, Emma L J Eyre, Rhys Morris, Mark Noon, Steven J Eustace, Joanne Hankey, Leanne M Raymond, Darren L Richardson

Summary: Nineteen professional football players (Age: 26±5 years; Height: 1.84±0.08 m; Mass: 83.4±8.9 kg) completed three x 30 m maximal acceleration sprints from a standing start before completing the Yo-Yo intermittent recovery test level 1. Three x 30 m maximal acceleration sprints were then repeated post-fatigue. Light gates recorded sprint times from 0-5 m, 0-10 m, 0-15 m and 0-30 m. Force platforms collected ground reaction force of the first stance phase of the sprint run. Differences between pre- and post-fatigue were observed in the sprint times over 0-15 m (P = 0.015; CI [0.007, 0.110]) and 0-30 m (P = 0.004; CI [0.056, 0.234]). Peak medial-lateral ground reaction force was lower (P = 0.045; CI [-0.146, -0.005]) post- than pre-fatigue. The ratio of force were significantly different between pre- and post-fatigue for the medial-lateral and anterior-posterior comparison (P = 0.017; CI [-0.063, -0.010]), and the medial-lateral and vertical comparison (P = 0.012; CI [-0.036, -0.007]). Football players altered their sprint mechanics to reduce medial-lateral loading and orient the force in an increased anteroposterior and vertical direction in order to maintain 0-10 m sprint performance. Practitioners should observe medial-lateral force contributions and improve sprint technical efficacy.



#14 Research in football: evolving and lessons we can learn from our mistakes

Reference: Sci Med Footb. 2021 May;5(2):87-89. doi: 10.1080/24733938.2021.1899275. Epub 2021 Mar 28.

Authors: Alan McCall

Summary: Football is evolving in many ways, including technical and physical demands as well as the scientific research underpinning and providing many recommendations to practitioners on how to optimise performance of players and by default, team performance. Evolution is a natural process and necessary to grow and develop and research into football is no different. Researchers are by nature, curious and inquisitive and trying to push the boundaries of knowledge; however, researchers are also humans and humans are open to making errors. The important point is that researchers learn from both their own and others' mistakes, evolving, growing and developing in response. By doing so will maximise the impact that research can have on the field.  With this commentary, I discuss lessons that can be learned from some common mistakes I and others have made in football (and sports) related research and some insights to evolve our profession for the better.



#15 The COVID-19 lockdown in Australia: a case study of exercise programming in male academy football players to prepare for return to play

Reference: Sci Med Footb. 2021 Nov;5(sup1):38-43. doi: 10.1080/24733938.2021.1983203. Epub 2021 Sep 26.

Authors: J A Sampson, N Gibson, M Whalan, S Veith

Summary: In 2020, the COVID-19 pandemic forced global lockdowns. Herein, we examine the effect of a lockdown exercise programme in a case-study of youth Australian A-league academy football players. Fifty-five u13-u15 age-grade players were provided with a 110 minute exercise programme including technical, tactical, cardiovascular and muscle strengthening exercises to perform 4 per week at home during the 10-week COVID-19 lockdown. Pre/Post lockdown, maximum aerobic speed was determined via the 30-15 intermittent fitness test (IFT). Exercise compliance was high (78.5% CI72.2-83.8) with an average of 3.15 sessions completed each week. All time-loss (TL) and medical attention (MA) injuries were recorded. Pre/Post lockdown, no difference in the mean incidence or burden of total time-loss (TL), match TL, training TL or medical attention (MA) injuries or injury rate ratio (1.21 CI:0.85-2.74) was observed. Similarly, no difference was observed in any injury incidence or burden data or the injury rate ratio (1.53 CI:0.85-2.74) when comparing the 9-week period prior to lockdown with the first 9 weeks post lockdown (9v9 only). A 9.6% (p = <0.01) increase was also observed in Pre/Post 30-15 IFT composite scores (18.7 CI: 18.3-19.1 to 20.5 CI:20-21). In this case study, compliance to the home-based exercise programme was high and no increase in injury was apparent. These findings must however be considered alongside the limitations associated within this case-study.



#16 Environmental surface contamination with SARS-CoV-2 in professional football clubs

Reference: Sci Med Footb. 2021 Nov;5(sup1):8-12. doi: 10.1080/24733938.2021.1941227. Epub 2021 Jun 22.

Authors: Yorck O Schumacher, Montassar Tabben, Karim Chamari, Peter Dzendrowskyj, Roald Bahr, Khalid Hassoun, Ahmed Khellil Abbassi, Meryem Bensaad, Bayan Al Barghouthi, Moza Alishaq, Rayyan Abdulaziz Attya Fadel, Andrew M Jeremijenko

Summary: We assessed SARS-CoV-2 contamination of random surfaces in football training facilities in an environment with a high prevalence of infections. In six clubs of the Qatar Stars League, surfaces of random locations (high-touch areas, ventilation systems, toilets, cleaning tools, freezers, pantries) in routinely cleaned training facilities, locker rooms, medical and administrative areas were swabbed for SARS-CoV-2. The swabs were screened for the presence of viral RNA using a SARS-CoV-2 qPCR Probe Assay. None of the 103 swabs reached a cycle threshold (cT) value ≤30 (strong viral presence, suggestive of potential surface transmission). Four samples showed cT values >30 and <35 (low quantity of virus) and 16 swabs returned a cT value ≥35 and <40 (inactive virus remnants). The remaining 83 samples were negative (cT value ≥40). Most samples with viral or viral remnant presence originated from high-touch areas. We did not find evidence for potential surface transmission in football club facilities when routine cleaning procedures are in place despite the presence of infected subjects.



#17 Surveillance for COVID-19 in the English Football League 2019-2020

Reference: Sci Med Footb. 2021 Nov;5(sup1):13-16. doi: 10.1080/24733938.2021.1900590. Epub 2021 Mar 22.

Authors: Subhashis Basu, Richard Higgins, Aneil Malhotra, Imtiaz Ahmad

Summary: Medical surveillance and risk mitigation protocols to reduce viral transmission have underpinned the return of elite football during the COVID-19 pandemic. This article describes the evidence-informed approach and surveillance findings from the English Football League across a 9-week period at the end of the 2019-20 season. Protocols were devised by the lead EFL Medical Advisor with specialist occupational medicine input. Isolation requirements for cases and contacts were in-line with UK Government regulations, with external contact tracing conducted by local public health authorities. Quantitative PCR testing was conducted twice weekly and within 72 hours of fixtures. Forty-three individuals, including 18 players returned positive tests. No positive results were returned after week 5 (round 10). Our findings support those from other leagues that with appropriate compliance, elite football can continue safely during this pandemic. We recommend that protocols and compliance should be revised as necessary according to community prevalence and changes in viral transmission dynamics.



#18 Mental health and well-being during COVID-19 lockdown: A survey case report of high-level male and female players of an Italian Serie A football club

Reference: Sci Med Footb. 2021 Nov;5(sup1):70-75. doi: 10.1080/24733938.2021.1962540. Epub 2021 Aug 24.

Authors: Andreas Ivarsson, Alan McCall, Stephen Mutch, Alessia Giuliani, Rita Bassetto, Maurizio Fanchini

Summary: The aim was to describe high-level footballers' levels and changes in mental health and well-being throughout a 8-week period of lockdown and restricted training during the COVID-19 pandemic. One-hundred and one players belonging to four teams (women's and men's, first and U19 teams) of the same Italian Serie A club participated in the study. Data were collected through an online questionnaire, and administered at 2, 3, 5, 7 and 9 weeks after the start of the lockdown . Well-being, positive and negative affects measurements were examined. Across the five measures, 36% of players reported clinical levels in depressive symptoms (scores ≤50) on at least one occasion. Thirteen percent of the players reported clinical levels on > 50% of the occasions. There was a decrease in depressive symptoms and negative affects over the period. No change was found in positive affects. High number of players reportedclinical levels of depressive symptoms compared to what was found previously in high-level athletes. The number decrease during the 8-week period. A similar trend was found for negative affects.Despite a higher prevalence in depressive symptoms earlier during lockdown, this improved as players progressed towards fewer restrictions.



#19 The sensitivity of countermovement jump, creatine kinase and urine osmolality to 90-min of competitive match-play in elite English Championship football players 48-h post-match

Reference: Sci Med Footb. 2021 May;5(2):165-173. doi: 10.1080/24733938.2020.1828614. Epub 2020 Oct 9.

Authors: Catherine E Beattie, Jack T Fahey, Samuel A Pullinger, Ben J Edwards, Colin M Robertson

Summary: The purpose was to examine changes from 90-minutes of competitive match-play in countermovement jump (CMJ), creatine kinase (CK) and urine osmolality (Uosm) in elite football players over a season and their association to match external load. Eighteen footballers participated. CMJ, CK and Uosm were collected 24-h pre-match and 48-h post-match. Match-performance data was examined using Prozone®. Post-match CK concentrations increased 49% (ES:0.66), while CMJ flight-time (FT), flight-time:contraction time ratio (FT:CT), take-off velocity (TV) and average power (AP) decreased 2.4-7.4% post-match (ES:0.39-0.63). CMJ height post-match reduced 4.2% (ES:0.35). CMJ FT and AP showed associations with high intensity distance covered (HID), high intensity number (HIN), explosive sprints (EXS) and medium intensity accelerations (r= -0.395 to -0.496). Changes in CMJ FT also displayed associations to total sprint distance (TSD), total sprint number (TSN) and medium intensity decelerations (r = -0.395-0.446). Increases in CMJ CT were associated with HIN (r=0.39), and CMJ AF with HIN, EXS and medium accelations/decelerations (r= -0.397 to 0.459) completed during the match. CMJ outputs from the push-off phase and countermovement phase were sensitive to change in neuromuscular fatigue. CK concentrations were sensitive to the match-play demands. This helps practitioners determine player readiness and has implications for individual recovery strategies.



#20 Study protocol: prevalence of low energy availability and its relation to health and performance among female football players

Reference: BMJ Open Sport Exerc Med. 2022 Jan 10;8(1):e001219. doi: 10.1136/bmjsem-2021-001219. eCollection 2022.

Authors: Jan H Rosenvinge, Marcus Smavik Dasa, Morten Kristoffersen, Gunn Pettersen, Jorunn Sundgot-Borgen, Jørn Vegard Sagen, Oddgeir Friborg

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Summary: Enduring low energy availability (LEA) is associated with several potentially serious physiological and mental conditions. LEA has been found highly prevalent among female elite athletes within endurance sports, thus hampering athletes' health and performance. The prevalence and the underpinning risk factors of LEA among female elite football players are less studied. One reason is that the existing self-report measures and technological devices to monitor energy intake and expenditure are inadequately adapted to capture the nature of the physical activity and energy expenditure among football players and are thus inaccurate. The present paper outlines a study protocol addressing the prevalence of LEA, the measurement of LEA and the correlations of LEA in terms of health and performance in female football players. Four studies will be conducted with the following aims (1) to evaluate the accuracy of global positioning systems (GPS)-based devices to monitor energy expenditure with indirect calorimetry as the gold standard, (2) to assess energy intake, quantify energy expenditure and investigate energy availability through self-report instruments, double labelled water (DLW) and GPS monitoring devices, (3) to determine the point prevalence of LEA using self-report instruments, DLW, dual-X-ray-absorptiometry (DXA) to quantify muscle and bone mass distribution and density, and a battery of hormonal analyses, and (4) to explore whether the prevalence of LEA varies across a full football season. Measures covering mental symptoms and psychological resources will be included, and a selection of biological measures derived from study 3. Measurements of DXA and DLW are resource-demanding and will be collected from one professional club (N~20 women). In contrast, the remaining data will be collected from four professional clubs (N~60 women) located in Bergen, the largest city within the Western region of Norway. Overall procedures and biobank storage procedures have been approved for data collection that will end in December 2024.



#21 Walking Football During Ramadan Fasting for Cardiometabolic and Psychological Health Benefits to the Physically Challenged and Aged Populations

Reference: Front Nutr. 2022 Jan 11;8:779863. doi: 10.3389/fnut.2021.779863. eCollection 2021.

Authors: Sueziani Binte Zainudin, Dee Dee A Salle, Abdul Rashid Aziz

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Summary: Concurrent exercise and intermittent fasting regimens for long periods have been shown to enhance cardiometabolic health in healthy individuals. As exercise and fasting confer health benefits independently, we propose that Muslims who are fasting, especially those experiencing health and clinical challenges, continually engage in physical activity during the Ramadan month. In this opinion piece, we recommend walking football (WF) as the exercise of choice among Muslims who are fasting. WF can be played by any individual regardless of the level of fitness, skills, and age. WF has been shown to elicit cardiovascular and metabolic stress responses, which are suitable for populations with low fitness levels. Most importantly, WF has the inherent characteristics of being a fun team activity requiring social interactions among participants and, hence, likely to encourage long-term consistent and sustainable participation.



#22 Contact times in professional football before and during the SARS-CoV-2 pandemic: Tracking data from the German Bundesliga

Reference: Eur J Sport Sci. 2022 Jan 25;1-17. doi: 10.1080/17461391.2022.2032837. Online ahead of print.

Authors: Dominik Szymski, Hendrik Weber, Gabriel Anzer, Volker Alt, Tim Meyer, Barbara C Gärtner, Werner Krutsch

Summary: The global SARS-CoV-2 pandemic led to a lockdown in team sports in March 2020. Because the risk of virus transmission seems to correlate with the duration of close contacts, data on contact times are necessary to assess the risk of virus transmission in sports. In this study, an optical tracking system was used to determine contact times between players of the two highest men's professional football leagues in Germany in the 2019-20 season and in the first half of the 2020-21 season. Contacts between players were defined as being within a two-metre radius during matches and were differentiated as either match-specific or non-match-specific. In total, 918 matches with 197,087 contacts were analysed. The mean overall contact time of one-to-one situations of 36 s (SD: ± 66) before the lockdown was reduced to 30 s after the lockdown (SD: ± 60) (p < 0.0001). In professional football, contacts between two players infrequently occur within a two-metre radius, averaging less than 35 s. Only 36 player pair contacts lasted for more than 15 min (0.00018%). The mean accumulated contact time per player with all others was 10.6 ± 6.9 min per match, with a decrease from 11.6 ± 7.0 min before the lockdown to 10.0 ± 6.6 min (p < 0.0001) after lockdown in the season 2019-20. The SARS-CoV-2 pandemic has resulted in a reduction in match-specific contacts of 25%. It seems questionable if such short contacts in open-air sports may lead to considerable virus transmission.



#23 A systematic review on methodological variation in acute:chronic workload research in elite male football players

Reference: Sci Med Footb. 2021 Feb;5(1):18-34. doi: 10.1080/24733938.2020.1765007. Epub 2020 May 24.

Authors: Albert Wang, Jack Healy, Nicholas Hyett, Geoffroy Berthelot, Katrine Okholm Kryger

Summary: The aim was to investigate and evaluate the methodological variation in research on acute:chronic workload ratio (ACWR) and injury in elite male football players. Relevant literature was electronically searched on PubMed, Web of Science, ScienceDirect, and Embase. Additional literature was obtained from studies' bibliographies and authors. Cohort studies investigating the effects of ACWR on male elite footballer injuries were included. Information regarding study population, time frame, protocol, injury classification, and statistical analysis were elucidated. Database searches led to 2,689 articles. After full text screening, twelve articles remained. All studies were of poor quality. Five studies had GPS-derived workload measures with consideration of running intensity zones, though little consensus over zone thresholds were found. Nine studies incorporated rated perceived exertion data; heterogeneity in exposure type and data collection timing was observed. All studies applied rolling average ACWRs, exploring 1:2, 1:3, and 1:4-week load ratio windows. Differences in data grouping, inference or regression analysis, and other statistical methods were noted. Existing literature displayed methodological heterogeneity. Future studies should consider consulting guidelines for developing prognostic studies and further examine causal links between workload and injury. From that basis, decisions around ACWR definitions, workload measures, and statistical methods may be more appropriately made.



#24 External load differences between elite youth and professional football players: ready for take-off?

Reference: Sci Med Footb. 2021 Feb;5(1):1-5. doi: 10.1080/24733938.2020.1789201. Epub 2020 Jul 9.

Authors: Kobe C Houtmeyers, Arne Jaspers, Michel S Brink, Jos Vanrenterghem, Matthew C Varley, Werner F Helsen

Summary: This study examines differences in weekly load between the first (FT) and the under 19 team (U19) within a professional football setting. Data were collected in 11 FT and 9 U19 players (2016-2017 season). FT data was divided into weeks with (FT-M1) or without (FT-M0) a mid-week match. Indicators were total distance (TD) and TD at 12-15, 15-20, 20-25 and >25 km‧h-1 and were analysed as external load (m), intensity (m‧min-1) and load monotony (a.u.). TD-based load was higher for U19 compared to FT-M0 (very likely moderate) and FT-M1 (likely large). Differences at higher velocities were substantially less (trivial to possibly small), with TD >25 km‧h-1 being lower than FT-M0 (very likely moderate) and FT-M1 (likely small). All intensity indicators were lower for U19 (likely small to almost certainly large). Load monotony was higher compared to FT-M1 (possibly small to almost certainly very large). Compared to FT-M0, monotony was higher for TD (possibly very large) and TD >25 km‧h1 (possibly moderate) but lower for TD 12-15 (possibly small) and 15-20 km‧h1 (likely moderate). So, despite higher weekly external loads at low velocity for elite youth players, external intensity and load variation increases when these players may transition to professional football.



#25 Design and Implementation of Football Player Training Management System Based on Intelligent Image

Reference: Appl Bionics Biomech. 2022 Jan 11;2022:6091557. doi: 10.1155/2022/6091557. eCollection 2022.

Authors: Yang Sun, Changjun Hu

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Summary: This article is aimed at studying the design and implementation of a football player training management system based on smart images. Based on the analysis of the importance of informatization for scientific football training, system performance requirements and intelligent image detection technology, the football player training management is designed. The overall architecture of the system, and the detailed design of each functional module of the system. It mainly includes football player information management module, football player training plan viewing module, training goal formulation module and training information feedback module. The realization of the training management system relies on intelligent image technology to detect and track athletes. Finally, the performance of the system was tested. The test results show that the expected response time of each module of the system when different numbers of users are accessed is within 3 seconds. The longest actual time is 2.64 s, and the actual shortest time is 1.18 s. It can be seen that the response time of the system meets the demand. At the same time, the system throughput rate meets the requirements of this article, and the user pass rate is also above 95%, indicating that the performance of the football player training management system designed in this article is better.



#26 Do environmental temperatures and altitudes affect physical outputs of elite football athletes in match conditions? A systematic review of the 'real world' studies

Reference: Sci Med Footb. 2022 Feb 1;1-12. doi: 10.1080/24733938.2022.2033823. Online ahead of print.

Authors: Garrison Draper, Matthew D Wright, Ai Ishida, Paul Chesterton, Matthew Portas, Greg Atkinson

Summary: Players involved in the various football codes compete throughout the calendar year around the world. Therefore, environmental stressors such as temperature and altitude should be considered in preparation for, and during, matches. We aimed to systematically review the observational and quasi-experimental studies that have been specifically designed to quantify the effects of temperature (hot or cold) high altitude on in-match physical performance indicators. A search of electronic databases (Web of Science, Scopus, SPORTDiscus, PubMed/MEDLINE) was conducted, with 19,424 papers identified as relevant. Following sifting in relation to the eligibility criteria, 12 papers were deemed directly relevant. The reviewed studies scored 6-9 (on a 0-9 scale) for quality assessment using a previously used scale. The major outcome variables relevant to the current review were total distance (m), high-speed running (m) and high-speed runs (count) measured during matches. Standardized effect sizes (ES) were heterogeneous across studies for total distance (ES: -0.96 to -0.14) and high-speed running (ES: -0.69 to 0.12) for >1000 m vs sea-level, time spent at the given altitude being a putative factor for this heterogeneity. Heat had mainly detrimental effects on performance, but ES were, again, heterogeneous across studies (ES: -1.25 to 0.26), dependent on temperature. Given the small number of studies that involved mostly male athletes, and large heterogeneity across studies, more research needs be conducted on physical performance in these environmental conditions, with attention paid to standardizing outcomes and broadening the approaches of studies to guide future decision-making in professional sporting environments.



#27 Levelling the playing field: Exploring inequalities and exclusions with a community-based football league for people with experience of mental distress

Reference: Aust Occup Ther J. 2022 Jan 23. doi: 10.1111/1440-1630.12791. Online ahead of print.

Authors: Anna Pettican, Ewen Speed, Wendy Bryant, Cherry Kilbride, Peter Beresford

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Summary: Sport workforce strategy in the United Kingdom (UK) has identified the occupational therapy profession as being ideally positioned to contribute to public health agendas relating to tackling physical inactivity amongst marginalised populations, such as disabled people and people with experience of mental distress. However, a robust understanding of the enablers, restrictions, and exclusions such groups encounter when seeking to participate in sport and physical activity is currently lacking. This study aimed to gain an in-depth understanding of the different ways people with experience of mental distress talked about their participation in a community-based football league in England, in the UK. Nine people took part in this strand of a larger participatory action research (PAR) study, which used go-along interviews as the method of data collection. In alignment with PAR seeking to address power imbalances, the data from the go-along interviews were analysed through a Foucauldian lens using a collaboratively produced analytic framework. Participants constructed the community-based football league as fostering feelings of purpose and belonging, against a backdrop of them describing experiencing stigma and exclusion when seeking to be active in their wider communities. They used the concept of occupational marginalisation to further interpret their situation. Understanding why and how people participate in football extends beyond seeing it as an individual exercise to shared social lives and occupations. With this perspective, occupational therapists could address occupational marginalisation in partnership with community sports organisations, collaborating for wider social change beyond specialist services.


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