Latest research in football - week 18 - 2022

#1 Analysis of team success based on match technical and running performance in a professional soccer league

Reference: BMC Sports Sci Med Rehabil. 2022 May 5;14(1):82. doi: 10.1186/s13102-022-00473-7.

Authors: Marcin Andrzejewski, José M Oliva-Lozano, Paweł Chmura, Jan Chmura, Sławomir Czarniecki, Edward Kowalczuk, Andrzej Rokita, José M Muyor, Marek Konefał

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9069775/pdf/13102_2022_Article_473.pdf

Summary: The aims of this study were to (1) determine the match technical and running performance required by different teams based on their final ranking position in a professional soccer league; and (2) analyze the correlation between teams' success at the end of the season and variables related to match technical and running performance. These performance data were collected during a total of 612 matches in the German Bundesliga. The final ranking position and the total of points obtained by each team at the end of the season were registered for the analysis of the correlation between team success and performance. The main findings were that there was a significant interaction (p < 0.05) between the ranking position, and both match technical and running performance. However, goals scored, saved shots on goal by the goalkeeper, assists, allowed shots on goal, goals conceded, ball possession ratio and successful passes from open play were the variables with the strongest correlation (r > 0.7; p ≤ 0.01) with the total of points obtained at the end of the season. Strength and conditioning coaches may consider these results to develop adequate training strategies, which may not only optimize performance but also reduce the injury risk.

 

 

#2 Change of Direction Speed in Youth Male Soccer Players: The Predictive Value of Anthropometrics and Biological Maturity

Reference: Pediatr Exerc Sci. 2022 May 5;1-7. doi: 10.1123/pes.2021-0178. Online ahead of print.

Authors: Yassine Negra, Senda Sammoud, Alan M Nevill, Helmi Chaabene

Summary: This study aimed to develop the optimal allometric body size/shape and a biological maturity model that predicted the change of direction (CoD) mean speed performance in youth male soccer players. One-hundred and fifteen youth soccer players (age: 12.4 [1.3] y) participated in this study. The 505 test was used to assess CoD mean speed performance. Anthropometric measurements comprised body height (cm), sitting height (cm), body mass (kg), fat mass (kg), lower limb length (cm), thigh length (cm), leg length (cm), foot length (cm), thigh girth (cm), and calf girth (cm). The maturity status was determined based on the maturity offset method. To identify size/shape and maturity characteristics associated with CoD speed performance, we computed a multiplicative allometric log-linear regression model, which was refined using backward elimination. The multiplicative allometric model exploring the association between 505 CoD mean speed performance and the different anthropometric characteristics in youth soccer players estimated that fat mass (P < .001), sitting height (P = .02), and maturity offset (P = .004) are the key predictors. More specifically, youths who are more mature and have a lower fat mass and a shorter trunk length, are likely to achieve a better CoD mean speed performance. These findings highlight the relevance of considering anthropometric and maturity characteristics in youth soccer players to support talent identification.

 

 

#3 Effects of Vest and Sled Resisted Sprint Training on Sprint Performance in Young Soccer Players: A Systematic Review and Meta-analysis

Reference: J Strength Cond Res. 2022 Apr 29. doi: 10.1519/JSC.0000000000004255. Online ahead of print.

Authors: Luis Miguel Fernández-Galván, Arturo Casado, Amador García-Ramos, Guy Gregory Haff

Summary: The aim of the meta-analysis was to determine the effect of resisted sprint training (RST) on sprint performance in young (<20 years) soccer players and to analyze whether the training equipment (sled or vest) and magnitude of the resistive load (above or below 20% of body mass [BM]) influences the long-term adaptations in sprint performance. Resisted sprint training reduced the acceleration phase time [standardized mean difference (SMD) = -0.41], with greater reduction in sprint time occurring in response to applying resistance with a vest (SMD = -0.70) when compared with a sled (SMD = -0.27). Similar reductions were determined for resistive loads <20% (SMD = -0.55) and ≥20% of BM (SMD = -0.31). Full sprint time showed a small reduction after RST (SMD = -0.36), regardless of the training equipment (sled: SMD = -0.44; vest: SMD = -0.26) and resistive load (<20% of BM: SMD = -0.40 ≥ 20% of BM: SMD = -0.21). There was a small and nonsignificant reduction in the maximum-velocity phase after RST (SMD = -0.25), which was comparable when the training was performed with vest (SMD = -0.34) or sled (SMD = -0.22). No significant differences in the changes of the acceleration phase time (SMD = 0.05) or full sprint time (SMD = 0.08) were observed between the experimental (sled or vest RST) and control groups (only soccer or unresisted sprint training). In conclusion, RST is effective to improve sprint performance in young soccer players, but the improvements are not superior to unresisted sprint training.

 

 

#4 Evaluation of Visual Skills in Soccer Referees and Assistant Referees

Reference: Med J Islam Repub Iran. 2021 Dec 19;35:169. doi: 10.47176/mjiri.35.169. eCollection 2021.

Authors: Amir Houshang Behesht Nejad, Tohid Seif Barghi, Bahar Hassanmirzaei, Leila Ghanbari, Homa Naderifar

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9035235/pdf/mjiri-35-169.pdf

Summary: As a soccer referee or an assistant referee, having perfect visual skills is mandatory, which will help make quick and accurate decisions in the field of the play and during matches; however, this skill is not well studied among referrers. This study aimed to assess the visual skills of referees and assistant referees. Men's professional referees and assistant referees working for the Iran football federation were investigated in 2019. The visual skill investigation consists of the evaluation of static visual acuity, color vision, stereoacuity, intraocular pressure, confrontation test, and eye anatomical assessment with slit lamp. The statistical analysis was performed using the SPSS software Version 18. In this study, 159 men's professional referees and assistant referees with a mean age of 35.52±5.39 were selected. The results of this study showed that 1.88% of the referees and assistant referees had color blindness dyschromatopsia) and 3.14% of them needed more follow-up examinations. The mean spherical equivalent of examined eyes was -0.42D in the right eye and -0.16 D in the left eye.  Our results showed that referees and assistant referees both had some kind of visual skill deficiencies. As visual skills are among the fundamental skills for success in referees in dynamic sports such as soccer, all of them must undergo visual skill assessments during the precompetition period to avoid any errors in judgment due to visual disturbances.

 

 

#5 Analysis of professional soccer players in competitive match play based on submaximum intensity periods

Reference: PeerJ. 2022 Apr 26;10:e13309. doi: 10.7717/peerj.13309. eCollection 2022.

Authors: Eduardo Caro, Miguel Ángel Campos-Vázquez, Manuel Lapuente-Sagarra, Toni Caparrós

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9053299/pdf/peerj-10-13309.pdf

Summary: The main objective of this study is to analyse sub-maximum intensity periods (SubMIP's) manifested by professional soccer players during official matches (number of events and time spent in each event), according to the player position, match halve and match, and also to group the players according to their SubMip values during the competition. We collected a total of 247 individual records of 14 players using Global Positioning System (GPS) during 15 official league matches (Azerbaijan Premier League 2019-2020). We calculated both the number of SubMIPs events and the time each player spent in the SubMIPs zone (threshold of 85% MIP). We analysed the possible independence of the variables with the Kruskal-Wallis test and the possible specific relationships between the groups using a post-hoc analysis with Dunn's test. In order to explore the possible distribution of physical demands in homogeneous groups, a cluster analysis was performed. The statistical analysis showed significant differences between the individual variables in the number of events and in the time spent by the player above the threshold in distance covered at speed >19.8 km/h (HSR), distance covered at speed >25.2 km/h (Sprint), acceleration density (AccDens), mean metabolic power (MetPow), metres per minute (Mmin) and high metabolic load distance >25.5 W/kg (HMLD). Differences were also found according to the playing position in MetPow, Mmin and between halves in AccDens, MetPow, Mmin. In the clustering based on the time spent by the player in SubMIPs, three main groups were described: (1) the centroid was located in lower values in each of the variables; (2) there were an accentuation of the AccDens variable; (3) all the variables, except AccDens, were accentuated. The main differences with regard to SubMIPs were related to the player's individual physical performance and not to position. However, the player's position could act as an attractor and show significant differences during matches.

 

 

#6 Soccer, safety and science: why evidence is key

Reference: Policy Brief (Inst Secur Stud). 2021 Mar;2021:159. Epub 2021 Mar 26.

Authors: Christina Laurenzi, Mark Tomlinson, Zwelibanzi Skiti, Mary Jane Rotheram-Borus

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9053516/pdf/nihms-1746114.pdf

Summary: Sports-based violence prevention programmes have broad appeal, including among police, policy makers and politicians. This policy brief presents a case study of the Eyethu Soccer League, a behavioural intervention that was carefully planned, implemented and evaluated - and yet did not achieve its aims. Findings caution against 'easy wins' and suggest that short-term skills-building programmes may struggle to solve structural challenges.

 

 

#7 In National Collegiate Athletic Association Men's and Women's Soccer Athletes There Is a Low Rate of Lumbar Spine Injury, Women Suffer More Recurrent Injuries than Men, and Most Injuries Occur in the Preseason

Reference: Arthrosc Sports Med Rehabil. 2022 Jan 29;4(2):e705-e711. doi: 10.1016/j.asmr.2021.12.015. eCollection 2022 Apr.

Authors: Nicolas P Kuttner, Aaron C Llanes, Sailesh V Tummala, Joseph C Brinkman, Kade S McQuivey, Jeffrey D Hassebrock, Justin L Makovicka, Anikar Chhabra

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9042889/pdf/main.pdf

Summary: The purpose was to use the National Collegiate Athletic Association Injury Surveillance Program (NCAA-ISP) from the 2009-2010 through the 2014-2015 seasons to report lumbar spine injury rates, characteristics, and time lost from sport in soccer players. Characteristics of lumbar spine injuries by season, competition/practice, and time lost from sport were determined using the NCAA-ISP database. Rates of injury were calculated as the number of injuries divided by the number of athlete exposures (AEs). AEs are any athlete participation in a competition or practice. Incidence rate ratios (IRRs) were calculated to compare rates between event types and time of season. Injury proportion ratios (IPRs) were used to evaluate differences in injury rates between men and women. The NCAA-ISP estimated 4,464 LSIs over 5 years. The rate of LSI in men was 2.1/10,000 AEs and 3.0/10,000 AEs in women. Women were 1.43 times more likely to suffer an LSI compared to men. Women were 2.15 times as likely to suffer an LSI in competition compared to in practice while men were 1.10 times as likely. Women were 2.15 times as likely to be injured in the preseason compared to the regular season, while men were 3.76 times as likely. Non-contact injuries were the most common cause of lumbar spine injuries (LSIs) in men (35%); however, contact injuries were more common in women (33%). Most athletes both male (57%) and female (59%) returned to play within 24 hours. This study provides information on the characteristics of LSIs in NCAA soccer. The overall injury rate to the lumbar spine is relatively low. Injury rates are highest in the preseason and in competition. Women suffer from more recurrent LSI's than men, and men acquired more injuries through non-contact mechanisms. More than one-half of athletes returned to sport within 24 hours.

 

 

#8 Chronic Effects of Heavy Load Activity Performed Before Resistance Training Sessions on the Physical Performance of Youth Soccer Players

Reference: Int J Exerc Sci. 2022 Feb 1;14(6):1421-1434. eCollection 2021.

Authors: Guilherme Borsetti Businari, Julio Benvenutti Bueno de Camargo, Paulo Henrique Barbosa, Felipe Alves Brigatto, Marcelo Saldanha Aoki, Tiago Volpi Braz, Charles Ricardo Lopes

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9017858/pdf/ijes-14-6-1421.pdf

Summary: The adoption of resistance training (RT) programs has been shown to positively influence sports performance-related parameters. However, the chronic effects of maximal strength protocols on the performance of soccer players are not completely investigated. The aim of this study was to evaluate the effects of performing two repetition maximum (2RM) before a resistance training session on the physical performance of youth soccer players. Seventeen players (under-20 category) were allocated in one of the following groups: 2RM + resistance training group (2RM + RT, n = 8) and resistance training group (RTG, n = 9). Both groups performed the same RT protocol during experimental weeks. However, the 2RM + RT performed 1 set of 2RM for 4 exercises, previously to RT protocol. Pre and post intervention period, one repetition maximum of the back squat exercise (1RMSQUAT), sprint time (15m-sprint test), countermovement jump (CMJ), repeated sprint ability (RSABEST and RSAMEAN), and yo-yo intermittent recovery test level-2 (YYIRT2) were assessed. Total load lifted (TLL) during the experimental weeks was also collected. Significant increases in 1RMSQUAT (2RM + RT: +45.1%, d = 4.40; RTG: +32.3%, d = 1.84), 15m sprint (2RM + RT: -9.0%, d = 7.9; RTG: -8.8%%, d = 3.2), CMJ (2RM + RT: +2.3%, d = 0.17; RTG: +0.8%, d = 0.07), RSABEST (2RM + RT: -2.4%, d = 0.6; RTG: -2.3%, d = 1.04), RSAMEAN (2RM + RT: -2.9%, d = 1.33; RTG: -3.4%, d = 1.78), YYIRT2 (2RM + RT: +12.0%, d = 0.82; RTG: +12.1%, d = 0.63) (all p < 0,05) were observed for both groups on pre to post-intervention periods, with no significant difference between groups. Therefore, the 2RM + RT protocol did not promote additional increase on performance of young soccer players.

 

 

#9 High-Risk Environmental Conditions Attenuates Performance Efficiency Index in NCAA DI Female Soccer Players

Reference: Int J Exerc Sci. 2022 Mar 1;15(6):442-454. eCollection 2022.

Authors: Maxine Furtado Mesa, Jeffrey R Stout, David H Fukuda, Michael J Redd, Adam J Wells

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9022704/pdf/ijes-15-6-442.pdf

Summary: The purpose of this study was to evaluate the effects of environmental conditions on running performance and performance efficiency index (Effindex). Performance data recorded using Polar Team Pro sensors from eight collegiate female soccer players in nine matches were analyzed during the 2019 competitive season. Effindex and running performance, including total distance covered (TDREL) and distance covered in five speed thresholds relative to minutes played, were examined for indications of fatigue with respect to environmental conditions, including ambient temperature and relative humidity. Matches were separated into three groups based on environmental conditions: Low-Risk (n = 2 matches), Moderate-Risk (n = 3 matches), or High-Risk (n = 4 matches). Speed thresholds were grouped as follows: walking (WALKREL), jogging (JOGREL), low-speed running (LSRREL), high-speed running (HSRREL), and sprinting (SPRINTREL). A significant effect was observed for TDREL in all environmental conditions (η2 = 0.614). TDREL was significantly lower in the High-Risk (p = 0.002; 95.32 ± 12.04 m/min) and Moderate-Risk conditions (p = 0.004; 94.85 ± 9.94 m/min) when compared to Low-Risk (105.61 ± 9.95 m/min). WALKREL (p = 0.005), JOGREL (p = 0.005) LSRREL (p = 0.001), HSRREL (p = 0.035), SPRINTREL (p = 0.017), and Effindex (p = 0.0004) were significantly greater in Low-Risk conditions when compared to Moderate-Risk conditions. WALKREL (p = 0.005), HSRREL (p = 0.029), SPRINTREL (p = 0.005), and Effindex (p = 0.0004) were significantly greater in Low-Risk conditions when compared to High-Risk conditions. High-Risk environmental conditions may result in adverse performance in female collegiate soccer players.

 

 

#10 The Development of Executive Functions in High-Level Female Soccer Players

Reference: Percept Mot Skills. 2022 May 6;315125221096989. doi: 10.1177/00315125221096989.

Authors: Adam Beavan, Jan Spielmann, Paul Ehmann, Jan Mayer

Summary: Executive functions (EFs) are higher-level cognitive functions that help keep an individual's goal-oriented thoughts and actions aligned. While many studies have shown the importance of EFs in sport, a limitation in this literature is that female participants have been underrepresented. In this mixed-longitudinal study, we examined the development of EFs in a cohort of high performing female athletes. We collected data over five seasons in a large sample of 175 female soccer players (aged 12-29 years old) from the U14 - senior age groups of a professional German soccer club. Players undertook a large battery of cognitive tasks aimed at measuring higher-level cognitive functioning: a sustained attention task, a stop-signal task, a Go-No-go test, an N-Back Test, and both a 180°- and 360°-multiple-object tracking task. We used linear and non-linear mixed effect regressions to examine the relationship between age and EFs. Second order polynomial curves explained many of these relationships between age and EFs compared to their linear relationships. Negatively accelerated curves reveal that these players' cognitive abilities mainly developed before players reached early adulthood, with a performance plateau evident at around 21 years of age. Age explained low to moderate proportions of the variance in EFs (<1-50%), while cognitive development across playing positions was not a strong contributor to this variance (M = 2.1, SD = 2.1%). We concluded that age has a negatively accelerated relationship with EFs in female soccer players that does not differ between playing positions. These data support the idea that athletes require only a reasonable level of EF ability to perform at the highest level of their sport. Our research raises new questions regarding the validity of current EF measurement methods for inferring information about in-game use of these cognitive abilities.

 

 

#11 Preseason multiple biomechanics testing and dimension reduction for injury risk surveillance in elite female soccer athletes: short-communication

Reference: Sci Med Footb. 2022 May 6. doi: 10.1080/24733938.2022.2075558. Online ahead of print.

Authors: Carlos De la Fuente, Rony Silvestre, Roberto Yañez, Matias Roby, Macarena Soldán, Wilson Ferrada, Felipe P Carpes

Summary: Injury risk is regularly assessed during the preseason in susceptible populations like female soccer players. However, multiple outcomes (high-dimensional dataset) derived from multiple testing may make pattern recognition difficult. Thus, dimension reduction and clustering may be useful for improving injury surveillance when results of multiple assessments tools are available. Thus, we determined the influence of dimension reduction for pattern recognition followed by clustering on multiple biomechanical injury markers in elite female soccer players during preseason. We introduce the use of dimension reduction through linear principal component analysis (PCA), non-linear kernel principal component analysis (k-PCA), t-distributed stochastic neighbor embedding (t-sne), and uniform manifold approximation and projection (umap) for injury markers via grid search. Muscle strength, muscle function, jump technique and power, balance, muscle stiffness, exercise tolerance, and running performance were assessed in an elite female soccer team (n=21) prior to the competitive season. As a result, umap facilitated the injury pattern recognition compared to PCA, k-PCA, and t-sne. One of three patterns was related to a team subgroup with acceptable muscle conditions. In contrast, the other two patterns showed higher injury risk profiles. For our dataset, umap improved injury surveillance through multiple testing characteristics. Dimension reduction and clustering techniques present as useful strategies to analyze subgroups of female soccer players who have different risk profiles for injury.

 

 

#12 Staying in or Dropping Out of Elite Women's Football-Factors of Importance

Reference: Front Sports Act Living. 2022 Apr 14;4:856538. doi: 10.3389/fspor.2022.856538. eCollection 2022.

Authors: Ingrid Amalie Hoftun Bjerksæter, Pål Arild Lagestad

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9047016/pdf/fspor-04-856538.pdf

Summary: The average age of elite women footballers in Norway is 22.7 years, significantly lower than that of elite male footballers in Norway (26.5). This study examines the factors leading to elite female footballers ending their careers at a relatively young age, and those factors influencing other female elite players to continue. Semi-structured interviews were conducted with five female elite players who had ended their career at the age of 19-24, and four who were still active (age 26-31). Based on the age of the informants who had ended their career and the informants who were still active, this study defines "young age" as <25years of age. The female elite players experiences were analyzed and discussed in relation to earlier research. The results of the study show that the same factors affecting the early end of a career, also had an impact on continuing the career in the Norwegian top league, beyond the average age. A low level of internal and external motivation, poor financial circumstances, high stress load, long injury breaks, lack of playing time and other priorities, are all factors leading elite players to end their football careers at a young age. These factors are increasingly being addressed in relation to still active elite players, and this has an impact on the length of their playing career. Like earlier research, this study indicates that the emergence of Norwegian women's football in recent years has helped to improve conditions for being female elite players in the professional leagues in Norway.

 

 

#13 Youth International Experience Is a Limited Predictor of Senior Success in Football: The Relationship Between U17, U19, and U21 Experience and Senior Elite Participation Across Nations and Playing Positions

Reference: Front Sports Act Living. 2022 Apr 13;4:875530. doi: 10.3389/fspor.2022.875530. eCollection 2022.

Authors: Henrik Herrebrøden, Christian Thue Bjørndal

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9044071/pdf/fspor-04-875530.pdf

Summary: Athlete participation in youth international competitions is often regarded as crucial to the attainment of future success. However, the link between participation and performance in sports at youth levels and senior levels is unclear at best. To understand this relationship better we conducted two studies of male football players. In Study 1, we examined adult performance at the upper levels of football using a factor analysis and identified the characteristics that define what we termed a "Super Elite" level, which is the highest level of participation. This outcome measure was used in Study 2 to explore further the link between youth international experience and athletes' Super Elite experience. Overall, our results indicated that youth international experience is a limited predictor of participation at the Super Elite level of football. Participation at the U21 level was the strongest, most consistent predictor of Super Elite level participation. U17 participation was found to be either an insignificant or a negative predictor of subsequent participation in international football. The effect of U19 participation on later participation was partly significant, but weaker than the effect of U21 participation, and depended on the national context and the playing positions of the athletes. When looking at the effect of different youth career types, careers involving U21 international experience were the strongest predictors of later careers as Super Elite athletes. National governing bodies that want to ensure success in talent identification and development should therefore consider focusing fewer resources on youth international competitions in age categories before adulthood. A total of 1,482 players who had national football team experience at either the U17, U19, U21, or senior levels were included in our studies.

 

 

#14 Evaluation of Match Results of Five Successful Football Clubs With Ensemble Learning Algorithms

Reference: Res Q Exerc Sport. 2022 May 2;1-10. doi: 10.1080/02701367.2022.2053647. Online ahead of print.

Authors: Enes Filiz

Summary: Football, one of the most popular and loved sports branches, always keeps its excitement, ambition, passion, joy and sadness together. European football, the football capital, is an attraction for fans and footballers. In this study, the official match results (league, country cup, European cup) of five successful football clubs (Bayern Munchen, Barcelona, Juventus, Manchester City, Paris Saint Germain) in the five major leagues of European football (La Liga, Premier League, Serie A, Bundesliga, Ligue 1) were evaluated. For this analysis, ensemble learning algorithms (AdaBoost, Bagging) and machine learning algorithms (Naive Bayes, artificial neural networks, K-nearest neighbor, C4.5/Random forest/Reptree decision tree) were used. In addition, the attributes that play an active role in the classification of the match results of five successful football clubs were determined with the Symmetrical Uncertainty feature selection algorithm. As effective attributes, "Conceded goal," "Half time result," "Scoring first" and "Shooting accuracy" attributes revealed to be common for five successful football clubs. In general, it was observed that ensemble learning algorithms gave successful results and AdaBoost/ANN algorithm was determined as the most successful. On the basis of football clubs, the most successful classification result was achieved for Barcelona with a rate of 99.3%. Obtained outputs from Ensemble learning and feature selection help sport researchers and football club planners understand and revise the match results of current football match strategies. The study has mainly twofold: to find best performer ensemble and machine learning algorithm(s) for classifying match results and to extract important features on match results.

 

 

#15 Effects of training on plasmatic cortisol and testosterone in football female referees

Reference: Physiol Rep. 2022 May;10(9):e15291. doi: 10.14814/phy2.15291.

Authors: Antonella Muscella, Giulia My, Selmi Okba, Daniele Zangla, Antonino Bianco, Santo Marsigliante

Download link: https://physoc.onlinelibrary.wiley.com/doi/epdf/10.14814/phy2.15291

Summary: There is very little about the impact that sports training has on female football referees. Therefore, we determined the effects of a 40-week physical preparation, including a full football season, on plasma testosterone and cortisol concentrations and physical performance in female football referees. Plasma cortisol and testosterone concentrations were assayed together with fitness tests at the beginning of the training period (T0, in September), after 8 weeks from T0 (T1), at the mid of the season (T2, 24 weeks after T0), and at the end of the season (T3, in June, 40 weeks after T0). Plasma cortisol increased during the first period and up to T2 (from 15.4 ± 4.7 to 28.5 ± 3.9 µg/dl; p < 0.001), and then decreased at the end of the season (T3: 16.0 ± 2.4 µg/dl). Plasma testosterone concentration in T0 was 14.2±0.37 µg/dl and increased in T1 (57.1 ± 3.7 µg/dl) and T2 (47 ± 3.7 µg/dl) and then decreased in T3 (33.5 ± 2.8 µg/dl). Resting testosterone levels in women were very low (14,2 ± 0.37 µg/dl) (Figure 3c). Testosterone increased in T1 (57.1 ± 3.7 µg/dl) and T2 (47 ± 3.7 µg/dl) whilst, at the end of the season, its concentration decreased (33.5 ± 2.8 µg/dl) (Figure 3c). Significant improvements were observed in all physical performances during the observed period (ANOVA, p < 0.05). Finally, testosterone and cortisol concentrations significantly (p < 0.0001 for both) correlated with maximal oxygen consumption. In T1, testosterone concentration was also significantly correlated with running speed test (p < 0.001). In conclusion, training induces endocrine changes in order to maintain body homeostasis in women referees. It is important that coaches and sports scientists regularly observe changes in endocrine function induced by training and matches in female referees, because they can help maximize referees' performance and limit cases of overtraining.

 

 

#16 Epidemiology of Campus Football Injuries in Ningxia, China: Occurrence, Causes, and Management

Reference: Front Public Health. 2022 Apr 26;10:893541. doi: 10.3389/fpubh.2022.893541. eCollection 2022.

Authors: Hengyuan Liu, Sen Huang, Te Bu, Wei Jiang, Tao Fu, Liliang Zhao

Download link: https://www.frontiersin.org/articles/10.3389/fpubh.2022.893541/full

Summary: By 2022, the Chinese government intends to have more than 30 million primary-, middle- and high-school children and adolescents regularly participate in campus football. In contrast, epidemiology of campus football injuries is completely missing. The goal of this descriptive epidemiological study was to determine the current state of campus football injuries and then to recommend appropriate prevention and management strategies. This retrospective epidemiological study conducted a survey of students, physical education and football teachers in primary, middle and high schools in the Ningxia Autonomous Region to determine the campus football injuries that occurred throughout the preceding 12-month period. The survey comprised questions on demographic characteristics, the occurrence, causes, and management of campus football injuries. A total of 1,285 students and 200 teachers returned eligible surveys. 25.7% of students had encountered injury accidents while participating in campus football activities. 31.3% of high school students, 23.8% of middle school students, and 19.2% of primary school students have sustained injuries. Football competition, accounting for 45.4% of all injuries, is the leading cause of injury. Football class teaching, which accounted for 3.0% of all injuries, had the lowest injury rate of any campus football activity. Students and teachers reported that a lack of safety awareness and injury prevention education were the primary causes of injuries. Only 18.7% and 11.4% of students are familiar with first aid basics and cardiopulmonary resuscitation, respectively. 10.6% and 7.5% of students lack any first aid basics and skills, respectively. 43.9% of students lack insurance coverage for athletic injuries. 62.5% and 38.5% of teachers reported that schools lack first aid training and an emergency plan for injuries, respectively. Students in Ningxia's campus football programs have a high injury risk. Injury prevention and management strategies lag significantly behind the mainstream nationwide promotion of campus football in China.

 

 

#17 Influence of the COVID-19 Lockdown and Restart on the Injury Incidence and Injury Burden in Men's Professional Football Leagues in 2020: The UEFA Elite Club Injury Study

Reference: Sports Med Open. 2022 May 13;8(1):67. doi: 10.1186/s40798-022-00457-4.

Authors: Markus Waldén, Jan Ekstrand, Martin Hägglund, Alan McCall, Michael Davison, Anna Hallén, Håkan Bengtsson

Download link: https://sportsmedicine-open.springeropen.com/track/pdf/10.1186/s40798-022-00457-4.pdf

Summary: Studies on football and the coronavirus disease 2019 (COVID-19) have mainly focused on the lockdown consequences for player fitness, the resumption of football training, and how to safely restart the league play, but injury data are scarce. The aim was to describe the injury incidence and injury burden in men's professional football teams during the pandemic year of 2020. Nineteen teams in 12 countries prospectively registered data on player-exposure and time-loss injuries throughout 2020. All major football leagues were paused as a direct response to the pandemic in March 2020 and were thereafter completely cancelled or restarted after a lockdown interval of at least two months. Historical data from 43 teams in the same cohort during the five preceding years (2015-2019) were used as reference. Between-season and within-season comparisons were made for injury incidence (number of injuries per 1000 h) and injury burden (number of absence days per 1000 h) with 95% confidence intervals and interquartile ranges. There was no increased match injury incidence or injury burden following the restart in 2020 compared with other time periods of 2020 and the corresponding periods 2015-2019. There was an increased training injury incidence and injury burden immediately during the lockdown in 2020, and they remained elevated also following the restart, being higher in 2020 compared with 2015-2019, respectively. The injury characteristics during the first months of the new 2020/21 season (August/September-December) were similar between the five teams that cancelled their 2019/20 season in March 2020 and the 14 teams that restarted their season in May/June 2020. There was no increased match injury incidence or injury burden following the COVID-19 lockdown and restart of the football season in 2020, but training injury incidence and injury burden were elevated and higher than in 2015-2019.

 

 

#18 Isolated Obturator Internus Muscle Strain Injury in a Professional Football Player: A Case Report

Reference: Cureus. 2022 Apr 8;14(4):e23949. doi: 10.7759/cureus.23949. eCollection 2022 Apr.

Author: Alexandros Toliopoulos

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9080343/pdf/cureus-0014-00000023949.pdf

Summary: The present case report concerns an isolated obturator internus muscle strain. The patient, who was a 30-year-old professional, elite-level football player, suffered the injury during the warm-up before a football match. Isolated injuries of the obturator internus are very uncommon and they are extremely rarely reported in the literature. The diagnosis was made clinically, documented by magnetic resonance imaging. The rehabilitation program was conducted conservatively with physical therapy and kinesiotherapy. The patient's return to full athletic activity took place 2 weeks after the incident.

 

 

#19 Epidemiological Comparison of ACL Injuries on Different Playing Surfaces in High School Football and Soccer

Reference: Orthop J Sports Med. 2022 May 5;10(5):23259671221092321. doi: 10.1177/23259671221092321. eCollection 2022 May.

Authors: Micah S Ngatuvai, Jingzhen Yang, Sandhya Kistamgari, Christy L Collins, Gary A Smith

Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9083053/pdf/10.1177_23259671221092321.pdf

Summary: Anterior cruciate ligament (ACL) injuries are among the most common serious injuries to athletes in the United States. Among high school sports, the highest rates of ACL injury occur in soccer and football. To compare ACL injuries on artificial turf and natural grass using a nationally representative sample of high school athletes participating in football and boys' and girls' soccer. ACL injuries among high school athletes participating in football and soccer were obtained from the High School Reporting Information Online surveillance system during the 2007-08 through 2018-19 school years. National estimates and injury proportion ratios (IPRs) with 95% CIs were calculated for ACL injuries that occurred on artificial turf versus natural grass. A total of 1039 ACL injuries were reported, which represented an estimated 389,320 (95% CI, 358,010-420,630) injuries nationally. There were 74,620 estimated football-related ACL injuries on artificial turf and 122,654 on natural grass. Likewise, 71,877 of the estimated soccer-related ACL injuries occurred on artificial turf and 104,028 on natural grass. A contact-injury mechanism accounted for 50.2% of football-related ACL injuries on artificial turf and 60.8% on natural grass. For soccer-related ACL injuries, a noncontact mechanism predominated on artificial turf (61.5%) and natural grass (66.4%). Among all injuries, ACL injuries were more likely to occur on artificial turf than natural grass in both football (IPR, 1.23 [95% CI, 1.03-1.47]) and girls' soccer (IPR, 1.53 [95% CI, 1.08-2.16]); however, no significant association was found in boys' soccer (IPR, 1.65 [95% CI, 0.99-2.75]). Among lower extremity injuries, ACL injuries were more likely to occur on artificial turf than natural grass in both boys' soccer (IPR, 1.72 [95% CI, 1.03-2.85]) and girls' soccer (IPR, 1.61 [95% CI, 1.14-2.26]); however, the association was not significant in football (IPR, 1.17 [95% CI, 0.98-1.39]). ACL injuries were more likely to occur (ie, had larger IPRs) on artificial turf than natural grass; however, this relationship was not statistically significant for all sports.