Latest research in football - week 23 - 2021

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 Effects of a Congested Fixture Period on Speed and Power Performance of Elite Young Soccer Players 

Reference: Int J Sports Physiol Perform. 2021 Mar 10;1-7. doi: 10.1123/ijspp.2020-0280. Online ahead of print. 

Authors: Tomás T Freitas, Lucas A Pereira, Valter P Reis, Victor Fernandes, Pedro E Alcaraz, Paulo H S M Azevedo, Irineu Loturco 

Summary: The purpose was to investigate the effects of a match-congested period on straight and curve sprint performance, change of direction (COD) speed and deficit, vertical jumping ability, and half-squat (HS) mean propulsive power (MPP) output in young soccer players. A total of 15 under-20 elite male soccer players participated in 14 matches over 8 weeks. The following assessments were performed before and after the congested fixture period: squat and countermovement jumps, 17-m linear sprint, curve sprint test for the "good" (CSGS) and "weak" (CSWS) sides, modified 17-m Zigzag test, and HS MPP. Magnitude-based inferences and a paired t test were used to analyze pre-post changes in the assessed variables. Very likely (P < .05) decreases were noticed in 17-m sprint velocity (effect size [ES] [90% confidence limit; CL], -0.56 [-0.32 to -0.81]) and CSGS (ES [90% CL], -0.72 [-0.40 to 1.03]) after the 8-week period. A possible but nonsignificant impairment was revealed in CSWS (ES [90% CL], -0.18 [0.03 to -0.39]), and countermovement jump (ES [90% CL], -0.21 [-0.54 to 0.12]). Zigzag velocity (ES [90% CL], -2.90 [-2.45 to -3.36]) and COD deficit (ES [90% CL], 0.86 [0.52 to 1.20]) were almost certainly and significantly (P < .05) reduced and increased, respectively, after the match-congested period. An almost certain and significant (P < .05) reduction was found in HS MPP (ES [90% CL], -1.18 [-0.76 to -1.61]). Straight and curve sprint velocity, COD speed and deficit, and HS MPP were impaired after the match-congested period. Vertical jump height was possibly decreased. Seasonal phases comprising high volumes of soccer-specific training and competition seem to be detrimental to speed-power qualities in under-20 elite soccer players. 



#2 Case Report: Return to Sport Following the COVID-19 Lockdown and Its Impact on Injury Rates in the German Soccer League 

Reference: Front Sports Act Living. 2021 Feb 18;3:604226. doi: 10.3389/fspor.2021.604226. eCollection 2021. 

Authors: Dhruv R Seshadri, Mitchell L Thom, Ethan R Harlow, Colin K Drummond, James E Voos

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Summary: The Bundesliga made headlines for becoming the first major sports league to return to sport worldwide following COVID-19 lockdown. To-date, there lacks retrospective studies on longitudinal injury rates to elucidate the effect isolation measures had on the health and safety of professional athletes. This study sought to compare injury rates experienced by Bundesliga athletes before and after the COVID-19 lockdown. Data was collected from public injury and player reports regarding the Bundesliga, with injury defined as trauma resulting in loss of game time. Descriptive statistics were used to present differences in injury incidence between all Bundesliga Match days pre- and post-lockdown. Between the league's resumption and completion on May 16 and June 27, 2020, injuries occurred in 21 forwards (FW), 11 central midfielders (CM), 12 wide midfielders (WM), 16 central defenders (CD), 6 fullbacks (FB), and 2 goalkeepers. Players had 1.13 (95% CI 0.78, 1.64) times the odds of being injured following the COVID-19 lockdown, with a 3.12 times higher rate of injury when controlling for games played compared to injury rates pre-lockdown (0.84 injuries per game vs. 0.27 injuries per game). The most frequent injury group was muscular injuries with 23 injuries total, with 17% of athletes experiencing injury during their first competitive match following lockdown. Injury rate increased over 3-fold following COVID-19 lockdown. Athletes did not experience an increased rate of injury with more cumulative competitive matches played. High injury incidence for players yet to complete their first competitive match may imply suboptimal sport readiness following home confinement. 



#3 Spontaneous Pneumomediastinum in an Adolescent Soccer Player 

Reference: J Sports Sci Med. 2021 Mar 1;20(1):52-55. doi: 10.52082/jssm.2021.52. eCollection 2021 Mar. 

Authors: Akinori Kobayakawa, Hideki Hiraiwa, Shinya Ishizuka, Satoshi Yamashita, Hiroki Oba, Yusuke Kawamura, Takefumi Sakaguchi, Masaru Idota, Takahiro Haga, Takafumi Mizuno, Itaru Kawashima, Kanae Kuriyama, Shiro Imagama

Summary: Spontaneous pneumomediastinum (SPM) is an uncommon and usually benign self-limiting clinical disorder found in young people, often without apparent precipitating factors or diseases. A pressure gradient exists between the peripheral pulmonary alveoli and the hilum, and increased intra-alveolar pressure causes rupture of the terminal alveoli. We present the case of a 15-year-old male soccer player who presented with a complaint of anterior chest pain and dysphagia after stopping the strong ball with his chest. His symptom gradually progressed over hours. We can make the diagnosis of SPM using by chest X-ray and computed tomography (CT) scanning. His symptoms were gradually resolved over the course of approximately one week with no exercise and careful observation. We believe that our case provides very useful information to alert clinicians and coaches regarding this rare disease that may occur in anyone including adolescent soccer players. 



#4 Attacking Key Performance Indicators in Soccer: Current Practice and Perceptions from the Elite to Youth Academy Level 

Reference: J Sports Sci Med. 2021 Mar 1;20(1):158-169. doi: 10.52082/jssm.2021.158. eCollection 2021 Mar. 

Authors: Mat Herold, Matthias Kempe, Pascal Bauer, Tim Meyer

Summary: Key Performance Indicators (KPIs) are used to evaluate the offensive success of a soccer team (e.g. penalty box entries) or player (e.g. pass completion rate). However, knowledge transfer from research to applied practice is understudied. The current study queried practitioners (n = 145, mean ± SD age: 36 ± 9 years) from 42 countries across different roles and levels of competition (National Team Federation to Youth Academy levels) on various forms of data collection, including an explicit assessment of twelve attacking KPIs. 64.3% of practitioners use data tools and applications weekly (predominately) to gather KPIs during matches. 83% of practitioners use event data compared to only 52% of practitioners using positional data, with a preference for shooting related KPIs. Differences in the use and value of metrics derived from positional tracking data (including Ball Possession Metrics) were evident between job role and level of competition. These findings demonstrate that practitioners implement KPIs and gather tactical information in a variety of ways with a preference for simpler metrics related to shots. The low perceived value of newer KPIs afforded by positional data could be explained by low buy-in, a lack of education across practitioners, or insufficient translation of findings by experts towards practice. 



#5 Fitness and Performance Testing of Male and Female Beach Soccer Players-A Preliminary Investigation 

Reference: Front Sports Act Living. 2021 Feb 23;3:636308. doi: 10.3389/fspor.2021.636308. eCollection 2021. 

Authors: Malte N Larsen, Georgios Ermidis, João Brito, Cecilie Ørner, Clarice Martins, Luís Filipe Lemos, Peter Krustrup, Vincenzo Rago

Summary: This study aimed to compare performance on sand and a firm surface and to describe the physical capacity of male and female beach soccer players. Sixty-six male and 29 female competitive beach soccer players voluntarily participated in this study. Firstly, within-subjects test scores were compared to scores on a firm surface (criterion validity; n = 15 men) and reconducted on a second occasion (reliability; n = 51 men). Secondly, the best score on sand was retained to compare test performance between ages (classified as below 20, 20-30, and above 30 years) and sexes. Performance assessments included sprint time over 5 and 15 m (once on a firm surface and twice on sand), standing long jump (SLJ, once on a firm surface and twice on sand) and Yo-Yo intermittent recovery level 1 (Yo-Yo IR1, once on a firm surface and once on sand; only data for men were available). Five-m sprint and Yo-Yo IR1 performance on sand were not correlated to performance on a firm surface (P > 0.05). Test-retest reliability was acceptable for the 15-m sprint and SLJ tests (ICC > 0.90; CV < 5%). Performance in 15-m sprint and maximal sprinting speed were moderately lower in male players aged above 30 years. compared to players aged below 30 years (d = 0.35-0.42; P < 0.05). Irrespective of the age group, weight-bearing power-based performance mass was moderately to very largely higher in male players than in female players (d = 0.42-0.88; P < 0.05). The lack of a consistent relationship between performance on sand and on a firm surface might indicate the need to develop specific test batteries for sand-based athletes. Age-related differences in physical performance were evident only in sprint capacity. Further studies are warranted to elucidate our preliminary findings and to develop the sand specific tests. 



#6 The Accuracy of a Low-Cost GPS System during Football-Specific Movements 

Reference: J Sports Sci Med. 2021 Mar 1;20(1):126-132. doi: 10.52082/jssm.2021.126. eCollection 2021 Mar. 

Authors: Emiel Schulze, Ross Julian, Sabrina Skorski

Summary: An affordable player monitoring solution could make the evaluation of external loading more accessible across multiple levels of football (soccer). The present study aimed to determine the accuracy of a newly designed and low-cost Global Positioning System (GPS) whilst performing match-specific movement patterns. Sixteen professional male football players (24 ± 3 years) were assigned a GPS device (TT01, Tracktics GmbH, Hofheim, Germany) and completed two experimental trials. In each trial, a continuous protocol including seven movements (sideways cornering, diagonal cornering, accelerating, decelerating, backwards jogging, shuttle running, and skipping) adding up to 500 m, was completed. Time-motion data was compared with criterion distance and velocity (photo-cell timing gates and radar). Validity was assessed through the standard error of the estimate (SEE) and reliability through the coefficient of variation (CV; both with 95% confidence limits). For the total distance covered during the protocol, the system was found to be valid (SEE = 3.1% [2.2; 5.8]) and reliable (intra-device CV = 2.0% [1.2; 7.6]). Similar results were found for velocity (SEE = 3.4% [2.6; 4.8], CV = 4.7% [3.2; 8.5]). In conclusion, the present GPS system, a low-cost solution, was found to be a valid and reliable tool for measuring physical loading during football-specific movements. 



#7 Past-season, pre-season and in-season risk assessment of groin problems in male football players: a prospective full-season study 

Reference: Br J Sports Med. 2021 Mar 10;bjsports-2020-102606. doi: 10.1136/bjsports-2020-102606. 

Authors: Ernest Esteve, Marti Casals, Marc Saez, Michael Skovdal Rathleff, Mikkel Bek Clausen, Jordi Vicens-Bordas, Per Hölmich, Tania Pizzari, Kristian Thorborg

Summary: We assessed past-season, pre-season and in-season risk factors to investigate their association with an in-season groin problem in male amateur football players. Past-season groin-pain information and pre-season short-lever and long-lever adductor squeeze strength were obtained at baseline, together with anthropometrics (weight, lower limb lever length) and player age. In-season hip-related and groin-related sporting function was monitored every 4 weeks using the Sports and Recreation (Sport) subscale from the Hip And Groin Outcome Score questionnaire (HAGOS (Sport)). Groin problems, including time-loss groin injuries and groin pain irrespective of time loss, were collected over a 39-week competitive in-season. We estimated relative risk (RR), and 95% credibility interval (ICr) from logistic regressions fitted in a Bayesian framework. Players (n=245) suffering from groin pain during the past-season had 2.4 times higher risk of experiencing a groin problem in the new season (2.40 RR; 95% ICr 1.5 to 3.7). This risk was reduced by 35% (0.65 RR; 95% ICr 0.42 to 0.99) per unit (N·m/kg) increase in the long-lever adductor squeeze test. Player age, short-lever squeeze test and the HAGOS (Sport) scores were not associated with the risk of a groin problem. Past-season groin pain increased the risk of a groin problem in the new in-season. This risk was reduced by higher pre-season long-lever adductor squeeze strength. Past-season groin-pain information and long-lever adductor squeeze strength can be quickly obtained during pre-season to identify players with an elevated risk of in-season groin problems. This may be key to reduce these problems in the new season. 



#8 Is there meaningful influence from situational and environmental factors on the physical and technical activity of elite football players? Evidence from the data of 5 consecutive seasons of the German Bundesliga 

Reference: PLoS One. 2021 Mar 9;16(3):e0247771. doi: 10.1371/journal.pone.0247771. eCollection 2021. 

Authors: Paweł Chmura, Hongyou Liu, Marcin Andrzejewski, Jan Chmura, Edward Kowalczuk, Andrzej Rokita, Marek Konefał

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Summary: The study aimed to identify the effects of situational (match location, match outcome and strength of team/opponent team) and environmental (ambient temperature, relative humidity, WBGT, ground and weather condition) factors on the physical and technical activity of elite football on individual playing positions. Physical and technical activity were collected from 779 football players competing in the German Bundesliga during 5 domestic seasons, from 2014/2015 to 2018/2019, totalling 1530 matches. The data on players' physical and technical activity was taken from the IMPIRE AG system. Based on the available data, 11 variables were selected to quantify the match activity profiles of players. The results showed that situational variables had major effects on the technical performance (especially number of passes performed) but minor effects on physical performance. In turn, among the analysed environmental factors, temperature is the most sensitive, which affects the Total Distance and Sprint Efforts of players in all five positions. This investigation demonstrated that, given that passing is a key technical activity in modern football, players and training staff should be particularly aware that passing maybe affected by situational variables. Professional players are able to react and adapt to various environmental conditions, modifying physical activity depending on the needs in German Bundesliga. These results could help coaches and analysts to better understand the influences of situational and environmental variables on individual playing positions during the evaluation of players' physical and technical performance. 



#9 The Diagnostic-Measurement Method-Resting Energy Expenditure Assessment of Polish Children Practicing Football 

Reference: Diagnostics (Basel). 2021 Feb 18;11(2):340. doi: 10.3390/diagnostics11020340. 

Authors: Edyta Łuszczki, Anna Bartosiewicz, Katarzyna Dereń, Maciej Kuchciak, Łukasz Oleksy, Artur Stolarczyk, Artur Mazur

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Summary: Establishing the amount of energy needed to cover the energy demand of children doing sport training and thus ensuring they achieve an even energy balance requires the resting energy expenditure (REE) to be estimated. One of the methods that measures REE is the indirect calorimetry method, which may be influenced by many factors, including body composition, gender, age, height or blood pressure. The aim of the study was to assess the correlation between the resting energy expenditure of children regularly playing football and selected factors that influence the REE in this group. The study was conducted among 219 children aged 9 to 17 using a calorimeter, a device used to assess body composition by the electrical bioimpedance method by means of segment analyzer and a blood pressure monitor. The results of REE obtained by indirect calorimetry were compared with the results calculated using the ready-to-use formula, the Harris Benedict formula. The results showed a significant correlation of girls' resting energy expenditure with muscle mass and body height, while boys' resting energy expenditure was correlated with muscle mass and body water content. The value of the REE was significantly higher (p ≤ 0.001) than the value of the basal metabolic rate calculated by means of Harris Benedict formula. The obtained results can be a worthwhile suggestion for specialists dealing with energy demand planning in children, especially among those who are physically active to achieve optimal sporting successes ensuring proper functioning of their body. 



#10 Effects of Non-Sport-Specific Versus Sport-Specific Training on Physical Performance and Perceptual Response in Young Football Players 

Reference: Int J Environ Res Public Health. 2021 Feb 18;18(4):1962. doi: 10.3390/ijerph18041962. 

Authors: Damiano Formenti, Alessio Rossi, Tindaro Bongiovanni, Francesco Campa, Luca Cavaggioni, Giampietro Alberti, Stefano Longo, Athos Trecroci

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Summary: This study aimed to compare the effects of non-sport-specific and sport-specific training methods on physical performance and perceptual response in young football players. Seventy-nine under 11 participants were selected and assigned to non-sport-specific (NSSG), sport-specific (SSG), and control (CNTG) groups. The NSSG training protocol consisted of combined stimuli based on balance, agility, and jump rope drills. The SSG training protocol included technical exercises, defensive and offensive game-based drills, and a small-sided game. The CNTG included the participants not taking part in any sport training. All participants were tested for general motor coordination (Harre test), dynamic balance (Lower Quarter Y-balance test), and dribbling before and after 10 weeks of training (NSSG and SSG) or habitual activity (CNTG). At post-intervention, perceived enjoyment was requested by the Physical Activity Enjoyment Scale (PACES). A two-way repeated measure analysis of covariance was used to detect interactions and main effects of time and groups controlling for baseline values. Whereas, a one-way analysis of variance was used to evaluate PACES-related differences between groups. NSSG gained greater improvements (p < 0.05) compared with SSG in the Harre and Lower Quarter Y-balance tests, while dribbling skills improved similarly in both groups. Regarding PACES, NSSG and SSG presented a comparable perceived enjoyment. These findings suggest that a 10-week non-sport-specific training is an enjoyable practice capable to promote greater improvements in general motor coordination and dynamic balance compared with sport-specific training in youth football players. This can occur without impairment of football-specific skills. 



#11 Prevalence of Prediabetes and Type 2 Diabetes Mellitus in Football Players: A Novel Multi Football Clubs Cross Sectional Study 

Reference: Int J Environ Res Public Health. 2021 Feb 11;18(4):1763. doi: 10.3390/ijerph18041763. 

Authors: Sultan Ayoub Meo, Abdulelah Adnan Abukhalaf, Ali Abdullah Alomar, Omar Mohammed Alessa, Omar Yassin Sumaya, Anusha Sultan Meo

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Summary: Sports offer great benefits, improving health and reducing the risk of illnesses. This study's aim was to investigate the prevalence of prediabetes and type 2 diabetes mellitus in football players compared to population based non-elite athlete control subjects. Initially 1100 male volunteers, (550) football players, and (550) population based non-elite athlete control subjects were interviewed. After socio-demographic and medical history analysis, 756 (378) nonsmoker male football players and (378) nonsmoker male control subjects were recruited. The control subjects were not involved in regular sports activities such as football, volleyball, badminton, cricket, hockey, and swimming. Participants with a known history of anemia, blood diseases, diabetes mellitus, and malignancy were excluded from the study. The mean age of football players was 31.80 ± 5.46 years, Body Mass Index (BMI) was 26.40 ± 2.08 (kg/m2), and the mean age of control subjects was 32.32 ± 4.37 years, and BMI was 26.66 ± 1.87 (kg/m2). The selected football players have been playing football for about 2 h a day, 3 days per week, and so the total mean duration of playing football was 1.08 years. American Diabetes Association (ADA) based criteria on Glycated Hemoglobin (HbA1c) was used to investigate prediabetes and type 2 diabetes mellitus. In football players the prevalence of prediabetes was 30 (7.93%) and type 2 diabetes mellitus (T2DM) was 6 (1.59%) compared to population based matched non-elite athlete control subjects where the prediabetes was 71 (18.78%) and T2DM was 89 (23.54%) (p = 0.001). Among football players there was a 7-fold decrease in T2DM compared to control subjects. Football recreational activities markedly reduce the prevalence of prediabetes and T2DM. The study findings demonstrate the benefits of football and other such sport activities and emphasize the urgent need for promoting football based physical activities as a physiological preventive strategy against the globally growing diabetes epidemic. 



#12 Can a Community-Based Football Program Benefit Motor Ability in Children with Autism Spectrum Disorder? A Pilot Evaluation Considering the Role of Social Impairments

Reference: J Autism Dev Disord. 2021 Mar 13. doi: 10.1007/s10803-021-04933-w. Online ahead of print.

Authors: Katherine Howells, Carmel Sivaratnam, Ebony Lindor, Jason He, Christian Hyde, Jane McGillivray, Rujuta B Wilson, Nicole Rinehart

Summary: This non-randomised pilot study evaluated the impact of a community football program on motor ability in children aged 5-12 years with autism spectrum disorder. Sixteen children were evaluated at baseline-and-post attendance in a football program for a varied number of weeks and compared to 19 children engaging in treatment-as-usual. Primary analyses indicated a statistically significant increase in total MABC-2, aiming and catching, and balance scores for the intervention group, with no changes in scores in the comparison group. There were no changes in manual dexterity across either group. At a between group level, the changes in aiming and catching scores were significantly greater for the intervention group. Further analyses highlighted the potential importance of social impairments regarding aiming and catching.



#13 A public health collaboration between medical professionals and Japan's professional football league for rubella awareness

Reference: J Gen Fam Med. 2020 Oct 20;22(2):104-105. doi: 10.1002/jgf2.390. eCollection 2021 Mar.

Authors: Toshinori Nishizawa, Yuko Murashima, Yuichi Nakamura, Keigo Sugisawa, Hironobu Nishiori, Kengo Nakamura, Noriyuki Amano, Gautam A Deshpande, Hiroko Arioka

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Summary: A public health collaboration between medical professionals and Japan's professional football league for rubella awareness.



#14 Polymorphism of the angiotensin converting enzyme gene (ACE-I/D) differentiates the aerobic and speed performance of football players

Reference: J Sports Med Phys Fitness. 2021 Mar 17.  doi: 10.23736/S0022-4707.21.12060-2.

Authors: Daniel B Coelho, Eduardo M Pimenta, Izinara C Rosse, Emerson C de Oliveira, Lenice K Becker, João B Ferreira-JÚnior, Lilian M Lopes, Maria R Carvalho, Emerson Silami-Garcia

Summary: The aim was to evaluate the distribution of ACE-I/D polymorphisms on Brazilian football players performance in aerobic capacity, strength, and speed tests. The participants in this study were 212 Brazilian first division male football players genotyped in DD, ID. or II. Genotyping of DNA from leucocytes was performed using polymerase chain reaction and restriction fragment length polymorphism methods. We evaluated speed using a 30-m sprint test with speed measured at 10 m (V10), 20 m (V20), and 30 m (V30); muscular strength using counter-movement-jump and squat jump tests; and aerobic endurance using the Yo-Yo endurance test. The athletes were ranked in ascending order according to their performance in each test and divided into quartiles: first quartile (0-25%, Weak), second (25-50%, Normal), third (50-75%, Good), and fourth (75-100%, Excellent); these were clustered according to genotype frequency. We identified significant differences in the V20 test values and in the aerobic capacity test. Higher frequencies of the ACE-DD genotype were observed in the Excellent performance group in the V20. In the aerobic capacity test, higher frequencies of the ACE-II genotype were observed in Excellent and Good performance groups. Players with higher performance in anaerobic and aerobic tests are ACE-DD and ACE-II genotypes, respectively.



#15 Process Mining of Football Event Data: A Novel Approach for Tactical Insights Into the Game

Reference: Front Artif Intell. 2020 Jul 14;3:47.  doi: 10.3389/frai.2020.00047. eCollection 2020.

Authors: Pavlina Kröckel, Freimut Bodendorf

Summary: The paper explores process mining and its usefulness for analyzing football event data. We work with professional event data provided by OPTA Sports from the European Championship in 2016. We analyze one game of a favorite team (England) against an underdog team (Iceland). The success of the underdog teams in the Euro 2016 was remarkable, and it is what made the event special. For this reason, it is interesting to compare the performance of a favorite and an underdog team by applying process mining. The goal is to show the options that these types of algorithms and visual analytics offer for the interpretation of event data in football and discuss how the gained insights can support decision makers not only in pre- and post-match analysis but also during live games as well. We show process mining techniques which can be used to gain team or individual player insights by considering the types of actions, the sequence of actions, and the order of player involvement in each sequence. Finally, we also demonstrate the detection of typical or unusual behavior by trace and sequence clustering.


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