Latest research in football - week 10 - 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 Effects of Football Training and Match-Play on Hamstring Muscle Strength and Passive Hip and Ankle Range of Motion during the Competitive Season

Reference: Int J Environ Res Public Health. 2022 Mar 2;19(5):2897. doi: 10.3390/ijerph19052897.

Authors: Víctor Moreno-Pérez, Gil Rodas, Marcelo Peñaranda-Moraga, Álvaro López-Samanes, Daniel Romero-Rodríguez, Per Aagaard, Juan Del Coso

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Summary: Deficits in hamstring muscle strength and in hip range of motion (ROM) have been considered risk factors for hamstring muscle injuries. However, there is a lack of information on how chronic exposure to regular football training affects hamstring muscle strength and hip ROM. The aim of this study was to examine the longitudinal effect of football training and competition during a complete season on hamstring muscle strength and hip ROM in football players. A total of 26 semi-professional football players underwent measurements of isometric hamstring muscle strength and passive hip flexion/extension, and internal/external hip rotation (IR/ER) ROM during the football season (pre-season, mid-season, end-season). Compared to pre-season, hamstring muscle strength increased in the dominant (+11.1%, p = 0.002) and non-dominant (+10.5%, p = 0.014) limbs in the mid-season. Compared to mid-season, hamstring strength decreased in the dominant (-9.3%, p = 0.034) limb at end-season. Compared to the pre-season, hip extension ROM decreased in mid-season in the dominant (-31.7%, p = 0.007) and non-dominant (-44.1%, p = 0.004) limbs, and further decreased at end-season (-49.0%, p = 0.006 and -68.0%, p < 0.001) for the dominant and non-dominant limbs. Interlimb asymmetry for hip IR ROM increased by 57.8% (p < 0.002) from pre-season to mid-season. In summary, while hamstring muscle strength increased during the first half of the football season in football players, a progressive reduction in hip extension ROM was observed throughout the season. The reduced hip extension ROM suggests a reduced mobility of the hip flexors, e.g., iliopsoas, produced by the continuous practice of football. Consequently, hip-specific stretching and conditioning exercises programs should be implemented during the football season.



#2 Speed and Agility Predictors among Adolescent Male Football Players

Reference: Int J Environ Res Public Health. 2022 Mar 1;19(5):2856. doi: 10.3390/ijerph19052856.

Authors: Cíntia França, Élvio Gouveia, Romualdo Caldeira, Adilson Marques, João Martins, Helder Lopes, Ricardo Henriques, Andreas Ihle

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Summary: This study aimed to examine the associations between lower-body explosive strength (squat jump-SJ, and countermovement jump-CMJ), speed (10- and 35-m linear sprints), and agility (t-test) capacities, after controlling for crucial predictors such as chronological age (CA) and body composition. The sample was composed of 164 adolescent male football players from under 19, under 17, and under 15 age groups. Body fat percentage (BF%) was significantly and positively related to body mass, speed, and agility. In contrast, BF% was a significant negative predictor of lower-body explosive strength. Sprint and t-test times were significantly and negatively correlated with lower-body explosive strength. After controlling for CA and body composition, SJ was the most significant predictor, accounting for 36 to 37% of the variance observed in the 35 m linear sprint and the t-test performance. Our main results suggest that lower-body explosive strength, particularly in the SJ, is a significant predictor of male adolescent male football players' speed and agility capacities. Conversely, detrimental relationships between BF% and these outcomes were observed. Sports agents should consider lower-body explosive strength development as part of the youth football training process, particularly to improve maximal sprint and change of direction times, which are crucial to game performance.



#3 Biological, Psychological, and Physical Performance Variations in Football Players during the COVID-19 Lockdown: A Prospective Cohort Study

Reference: Int J Environ Res Public Health. 2022 Feb 26;19(5):2739. doi: 10.3390/ijerph19052739.

Authors: Giulia My, Santo Marsigliante, Antonino Bianco, Daniele Zangla, Carlos Marques da Silva, Antonella Muscella

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Summary: This prospective cohort study aimed to evaluate whether COVID-19 lockdown caused biological, psychological, and/or physical performance variations in footballers. We compared the 2018/2019 and 2019/2020 seasons evaluating the plasma volume, hematological parameters, iron/ferritin, creatine kinase, vitamin D, cortisol, testosterone, and physiological state of players of the Italian football major league (Serie A). Measurements were performed before the preparatory period (T0), at the beginning (T1) and in the middle (T2) of the championship, and in March (T3) and at the end of season (T4). The results showed that in the 2019/2020 season affected by the lockdown, the weight, BMI, and fat mass percentage were higher than in the previous season. Hematocrit, hemoglobin, red blood cells, and ferritin decreased during both seasons, more significantly than in the regular season. During both seasons, creatine kinase increased from T2 whilst iron concentrations decreased in T3. Testosterone increased in both seasons from T0 to T3 and returned to initial levels at T4; cortisol increased in T2 and T3 during the 2018/2019 season but not during the COVID-19 season. Physical performance tests revealed differences associated with lockdown. Thus, although from a medical point of view, none of the evaluated changes between the two seasons were clinically relevant, training at home during lockdown did not allow the players to maintain the jumping power levels typical of a competitive period.



#4 Dynamic Monitoring of Football Training Based on Optimization of Computer Intelligent Algorithm

Reference: Comput Intell Neurosci. 2022 Feb 28;2022:2199166.doi: 10.1155/2022/2199166. eCollection 2022.

Authors: Jin Gang

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Summary: Nowadays, with the development of computer science and technology, computer intelligent algorithms are more and more widely used in various industries. Every calculation formula in the computer intelligent algorithm has systematic logic and singleness, in order to expound the dynamic algorithm of football training optimized by the computer intelligent algorithm in detail. In this paper, the monitoring system using the computer intelligent algorithm can dynamically observe people or objects and systematically analyze them. This paper mainly studies the research of a football training dynamic monitoring system based on the computer intelligent algorithm and the design and optimization of the computer intelligent dynamic monitoring system in football training. Finally, the overall composition of the computer intelligent dynamic monitoring system and the application of the optimized computer intelligent dynamic monitoring system to the analysis of sample data are studied.



#5 Football players with long standing hip and groin pain display deficits in functional task performance

Reference: Phys Ther Sport. 2022 Feb 26;55:46-54. doi: 10.1016/j.ptsp.2022.02.023. Online ahead of print.

Authors: Eliza A Roughead, Matthew G King, Kay M Crossley, Josh J Heerey, Peter R Lawrenson, Mark J Scholes, Adam I Semciw, Benjamin F Mentiplay, Joanne L Kemp

Summary: The aim was to i)Compare functional task performance between football players with and without hip/groin pain. ii) Explore the relationship, and sex-specific effects, between functional tasks and the Copenhagen Hip and Groin Outcome Score (HAGOS) in players with hip/groin pain. 183 (38 women) football players with a self-reported history of >6months of non-time-loss hip/groin pain and a positive flexion-adduction-internal rotation test, and 61 (14 women) asymptomatic players participatd in this study. Participants completed the hop-for-distance (HFD), one leg rise (OLR), side bridge (SB) endurance, and HAGOS. Study aims were assessed using linear models, controlling for body mass index and age, incorporating sex-specific interaction terms. Players with hip/groin pain could not hop as far (adjusted mean difference: -9 cm, 95% CI: -15 cm to -2cm, P=0.012) and completed fewer OLR repetitions (adjusted mean difference -7, 95% confidence interval -11 to -3 repetitions, P=0.001) compared to asymptomatic players. Symptomatic women, but not symptomatic men, with worse HAGOS scores had lower SB endurance. Independent of sex, football players with worse HAGOS scores could not hop as far and completed fewer OLR repetitions. Football players with hip/groin pain demonstrated deficits in HFD and OLR with the performance of these tasks associated with their HAGOS results. The study identifies potential impairments that can be targeted as a component of rehabilitation programs for football players with hip/groin pain.



#6 The influence of tactical and match context on player movement in football

Reference: J Sports Sci. 2022 Mar 7;1-15. doi: 10.1080/02640414.2022.2046938. Online ahead of print.

Authors: Sam Gregory, Sam Robertson, Robert Aughey, Grant Duthie

Summary: Player movement metrics in football such as speed and distance are typically analysed as aggregates, sometimes outside of any specific tactical or match context. This research adds context to a player's movement over the course of a match by analysing movement profiles s and bringing together tools from the sport science and sports analytics literature. Position-specific distributions of player movement metrics: speed, acceleration and tortuosity were compared across phases of play and in-game win probability using 25 Hz optical player tracking data from all 52 matches at the 2019 FIFA Women's World Cup. Comparing the distributions using the Kolmogorov-Smirnov test and Wasserstein distances, differences were identified in these movement profiles across, in and out of possession phases, with small negligible overall positional trends across in-game win probabilities. In-game win probabilities are used in tandem with phases to present a player specific case study. The results demonstrate how sports analytics metrics can be used to contextualise a subset of movement metrics from sport science and provide a framework for analysis of further movement metrics and sports analytics modelling approaches.



#7 Executive summary: Elite women's football-Performance, recovery, diet, and health

Reference: Scand J Med Sci Sports. 2022 Mar 7. doi: 10.1111/sms.14145. Online ahead of print.

Authors: Magni Mohr, Joao Brito, Maysa de Sousa, Svein Arne Pettersen

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Summary: The present special issue of Scandinavian Journal of Medicine & Science in Sports focuses on performance, recovery, diet, and health in elite women's football. Beside this summary, an editorial, topic reviews, and original articles written by several of the most published authors in football research are presented. It is, for example, highlighted that there is a great gender inequality in football research in favor of men, especially within elite football populations. Therefore, the broad-spectrum content of the special issue with focus on several performance areas in women's football, recovery strategies, nutrition, and psychological factors is highly warranted. Several of the topics examined and data presented are examined for the first on elite women's football, and therefore, we hope that this special issue will contribute to gender balance the research and emphasis on football in both genders.



#8 Muscular heat shock protein response and muscle damage after semi-professional football match

Reference: Scand J Med Sci Sports. 2022 Mar 5. doi: 10.1111/sms.14148. Online ahead of print.

Authors: Håvard Wiig, Kristoffer T Cumming, Vilde Handegaard, Jostein Stabell, Matthew Spencer, Truls Raastad

Summary: A typical football match leads to neuromuscular fatigue and physical performance impairments up to 72-96 h post-match. While muscle damage is thought to be a major factor, damage on the ultrastructural level has never been documented. The purpose of this study was to investigate post-match cellular muscle damage by quantifying the heat shock protein (HSP) response as a proxy for protein damage. Muscle biopsies, blood samples, countermovement jumps, and perception of muscle soreness were obtained from twelve semi-professional football players 1, 24, 48, and 72 h after a 90-min football match. Muscle biopsies were analyzed for αB-crystallin and HSP70 in the cytosolic and cytoskeletal sub-cellular fractions by Western blotting. Fiber type-specific αB-crystallin and HSP70 staining intensity, and tenascin-C immunoreactivity were analyzed with immunohistochemistry. Blood samples were analyzed for creatine kinase and myoglobin. Within 24 h post-match, a 2.7- and 9.9-fold increase in creatine kinase and myoglobin were observed, countermovement jump performance decreased by -9.7% and muscle soreness increased by 0.68 units. αB-crystallin and HSP70 accumulated in cytoskeletal structures evident by a 3.6- and 1.8-fold increase in the cytoskeletal fraction and a parallel decrease in the cytosolic fraction. In type I and II fibers, αB-crystallin staining intensity increased by 15%-41% and remained elevated at 72 h post-match. Lastly, the percentage of fibers with granular staining of αB-crystallin increased 2.2-fold. Football match play induced a muscular HSP stress response 1-72 h post-match. Specifically, the accumulation of HSPs in cytoskeletal structures and the granular staining of αB-crystallin suggests occurrence of ultrastructural damage. The damage, indicated by the HSP response, might be one reason for the typically 72 h decrease in force-generating capacity after football matches.



#9 Common genetic basis of ALS patients and soccer players may contribute to disease risk

Reference: Neurol Sci. 2022 Mar 5. doi: 10.1007/s10072-022-05990-4. Online ahead of print.

Authors: Sigal Ben-Zaken, Beatrice Nefussy, Yoav Meckel, Alon Eliakim, Dan Nemet, Marc Gotkine, Dana Lorber, Aviva Zeev, Vivian E Drory

Summary: The aim of the present study was to determine the prevalence of the ACSL A/G single nucleotide polymorphism among athletes and patients with amyotrophic lateral sclerosis (ALS). ALS is a progressive neurodegenerative disorder of motor neurons that leads to paralysis and death usually within 3-5 years from onset. Previous epidemiological studies reported a higher risk of ALS among soccer players. The ACSL (long-chain-fatty-acid-CoA ligase 1) gene codes the long-chain fatty-acid-coenzyme A ligase family that plays a key role in lipid biosynthesis and fatty acid oxidation. The ACSL A/G polymorphism is associated with endurance trainability. One hundred and seventy-eight ALS patients, 172 athletes (60 soccer players, 112 middle- and long-distance runners), and 111 nonathletic controls participated in the study. Genomic DNA was extracted from blood or buccal cells according to the salting-out procedure. Genotypes were determined using the TaqMan allelic discrimination assay. The prevalence of the ACSL AA genotype was significantly higher among soccer players (35.0%) and ALS patients (39.3%) compared to runners (16.1%) and controls (18.0%). However, ALS GG carriers had a higher mortality rate. We postulate that soccer players and ALS patients carry a common genetic predisposition that is related to impaired fatty acid utilization. Moreover, while the A allele might be associated with a genetic predisposition toward ALS, especially among soccer players, the G allele might be associated with disease severity. Further research is needed in order to explore the role of the ACSL rs6552828 polymorphism in ALS.



#10 Physical loading in professional soccer players: Implications for contemporary guidelines to encompass carbohydrate periodization

Reference: J Sports Sci. 2022 Mar 6;1-20. doi: 10.1080/02640414.2022.2044135. Online ahead of print.

Authors: Liam Anderson, Barry Drust, Graeme L Close, James P Morton

Summary: Despite more than four decades of research examining the physical demands of match-play, quantification of the customary training loads of adult male professional soccer players is comparatively recent. The training loads experienced by players during weekly micro-cycles are influenced by phase of season, player position, frequency of games, player starting status, player-specific training goals and club coaching philosophy. From a macronutrient perspective, the periodization of physical loading within (i.e., match versus training days) and between contrasting micro-cycles (e.g., 1, 2 or 3 games per week schedules) has implications for daily carbohydrate (CHO) requirements. Indeed, aside from the well-recognised role of muscle glycogen as the predominant energy source during match-play, it is now recognised that the glycogen granule may exert regulatory roles in activating or attenuating the molecular machinery that modulate skeletal muscle adaptations to training. With this in mind, the concept of CHO periodization is gaining in popularity, whereby CHO intake is adjusted day-by-day and meal-by-meal according to the fuelling demands and specific goals of the upcoming session. On this basis, the present paper provides a contemporary overview and theoretical framework for which to periodize CHO availability for the professional soccer player according to the "fuel for the work" paradigm.



#11 Soccer players show the highest seasonal groin pain prevalence and the longest time loss from sport among 500 athletes from major team sports

Reference: Knee Surg Sports Traumatol Arthrosc. 2022 Mar 8. doi: 10.1007/s00167-022-06924-5.

Authors: Michele Mercurio, Katia Corona, Olimpio Galasso, Simone Cerciello, Brent Joseph Morris, Germano Guerra, Giorgio Gasparini

Summary: Groin pain is a widely recognized medical issue among athletes. Groin pain can affect both player and team performance and sometimes can be a career-ending injury. The aim of this study was to assess seasonal groin pain prevalence and the average seasonal time loss from sport for each injury in different team sport athletes. The hip and groin functionality at the beginning of the following season was also investigated. A cross-sectional study was undertaken on 600 team sport athletes (soccer, futsal, basketball, volleyball, and water polo players). The seasonal prevalence of groin pain, level of competition (professional and non-professional), time loss, and concomitant injuries in addition to groin pain were reported and analyzed. The Copenhagen Hip and Groin Outcome Score (HAGOS) was used to assess hip and groin pain and function related to sport and activity. Among the 506 (84%) players included, 123 players (24.3%) reported groin pain. Overall, soccer players reported the highest groin pain prevalence (32.5%) followed by futsal (25.5%), basketball (25.2%), water polo (17.6%) and volleyball players (13.6%). Professional soccer, futsal and basketball athletes showed higher groin pain prevalence in comparison with non-professional athletes (p = 0.02, p = 0.005 and p = 0.004, respectively). The mean time loss from sport due to groin pain was 60.3 ± 66 days in soccer, 41.1 ± 16.6 days in futsal, 31.5 ± 18 days in water polo, 37.2 ± 14.2 days in basketball and 50.8 ± 24.6 days in volleyball. Significantly lower HAGOS values were found in athletes with groin pain for all sports evaluated compared to athletes with no groin pain history (p = 0.0001). Longer time loss from sport was correlated with lower HAGOS values in soccer (p = 0.002) and futsal (p = 0.002) players with groin pain. Concomitant injuries were correlated with lower HAGOS values in water polo players (p = 0.03). Seasonal groin pain occurs in as many as one in four team sport athletes. Soccer players show the highest groin pain prevalence and the longest time loss from sport. Professional athletes report higher prevalence of groin pain in comparison with non-professional athletes. HAGOS appears to be a valid outcome instrument to measure groin pain, correlating with both time loss from sport and concomitant injuries in athletes.



#12 Effect of an Energy Drink On Muscle and Liver Damage Enzymes, And Cardiovascular Indices in Soccer Players

Reference: Sci Med Footb. 2022 Mar 10;1-7. doi: 10.1080/24733938.2022.2051728. Online ahead of print.

Authors: Fahimeh AdibSaber, Soleyman Ansari, Alireza Elmieh, Hadi Rajabzadeh

Summary: Despite emerging evidence about the influence of energy drinks on the quality of athletes' performance, there is little information about their effects on exercise-induced damage markers after long-term activities. This study aimed to investigate the acute effects of hype energy drink (HED) to ameliorate liver and muscle damage enzymes and cardiovascular indices-induced by a soccer match. A total of 22 elite male soccer players (age 20.36 ± 1.91) were recruited. Participants performed two experimental conditions, separated by a 14-day washout period. They consumed 2 × 250 ml of HED or placebo for 5 d before the soccer match, on match day, and for 1-day post-match. Measurements of muscle (CK and LDH), and liver (ALT, AST, and ALP) damage indices, and blood pressure (BP) parameters were taken at baseline, pre-match, post-match, and 24 h post-match. The results showed that the levels of ALT, AST, ALP, CPK, and LDH enzymes significantly decreased in HED condition from pre-match to 24 h post-match, compared with placebo (p < 0.001). Also, consumption of energy drinks reduced systolic, diastolic, and mean BP. In conclusion, elevated serum levels of muscle and liver damage enzymes and higher values of BP indices are improved 24 hours after soccer match following HED ingestion, compared to placebo. Therefore, it seems that consuming HED can lead to faster recovery of muscle and liver damage and improve recovery in soccer players.



#13 Multimodal imaging of soccer ball-related ocular posterior segment injuries

Reference: Eur J Ophthalmol. 2022 Mar 9;11206721221086230. doi: 10.1177/11206721221086230.

Authors: William Carrera, Caleb Ng, Jayson Koppinger, Asma Saud, Judy J Chen, Anita Agarwal, Robert N Johnson, J Michael Jumper, Brandon Lujan, H Richard McDonald

Summary: The purpose was to investigate the clinical and anatomic characteristics of soccer ball-induced posterior segment injuries in the era of modern multi-modal imaging. Retrospective case series of patients with soccer ball injury and diagnostic imaging from 2007 to 2020 at a single vitreoretinal practice. Eight patients met inclusion criteria. Fundus photographs (FP) and optical coherence tomography (OCT) were obtained in eight patients, fundus autofluorescence (FAF) in five patients, fluorescein angiography (FA) in three patients, and en-face OCT and OCT-Angiography (OCT-A) were obtained in two patients each. FA and FAF identified traumatic pigment epitheliopathy secondary to commotio. Increased hypo-autofluorescence was associated with shallow, peripheral retinal detachment on FAF. OCT of the macula displayed outer retinal changes associated with commotio, and offered insight into the acute and subacute changes of traumatic macular hole formation. A patient displayed foveal hyper-reflectivity in the shape of an hourglass with retinal cyst at the level of the external limiting membrane (ELM) as seen on OCT and En-face OCT. A patient with commotio involving the macula lacked microvascular changes on OCT-A. OCT, FA, and FAF imaging may aid in the work-up and management of the soccer ball-related posterior segment injuries.



#14 Analyzing the relationship between self-efficacy and impulsivity in amateur soccer referees

Reference: PeerJ. 2022 Mar 4;10:e13058. doi: 10.7717/peerj.13058. eCollection 2022.

Authors: José López-Aguilar, Rafael Burgueño, Alfonso Castillo-Rodriguez, Wanesa Onetti-Onetti

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Summary: Soccer referees (SRs) are exposed to stressful situations during the competition that can affect decision-making, could be affected by impulsivity during the competition and therefore, require optimal psychological skills. The objective of this study was to ascertain and analyze the relationship between levels of impulsivity and self-efficacy of amateur SRs in the senior category. A total of 21 Spanish SRs participated in this study (age 23.57 ± 2.40 years and 7.81 ± 2.58 seasons of experience). Self-efficacy data were collected with the REFS questionnaire between 48 and 72 h before the competition. The impulsivity data were collected using the UPPS-P questionnaire 60 min before the start the competition. The results indicate that SRs with higher self-efficacy have lower levels of impulsivity, specifically in the dimensions of negative urgency (p < 0.01), positive urgency (p < 0.05), lack of premeditation (p < 0.001), and lack of perseverance (p < 0.001), as well as lower global impulsivity (p < 0.01). However, the SRs with the highest self-efficacy also obtained higher levels in the sensation seeking dimension (p < 0.05). In conclusion, the main finding of this study showed that self-efficacy is influenced by SR impulsivity prior to competition. These novel facts allow us to discover aspects related to decision-making in refereeing that can be trained to reach optimal levels.



#15 Weekly Variations of Well-Being and Interactions with Training and Match Intensities: A Descriptive Case Study in Youth Male Soccer Players

Reference: Int J Environ Res Public Health. 2022 Mar 2;19(5):2935. doi: 10.3390/ijerph19052935.

Authors: Ana Filipa Silva, Rafael Oliveira, Stefania Cataldi, Filipe Manuel Clemente, Francesca Latino, Georgian Badicu, Gianpiero Greco, César Leão, Valerio Bonavolontà, Francesco Fischetti

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Summary: The aim of this study was two-fold: (i) analyze the weekly variations of well-being and training/match intensity measures in youth soccer players, and (ii) test relations between well-being and training intensity outcomes. The study followed a descriptive case study design. Twenty-seven under-17 male soccer players were monitored for well-being and training intensity parameters over seventeen consecutive weeks. An adjusted version of the Hooper questionnaire was used to monitor the perceptive sleep quality, readiness, fatigue, and delayed onset muscle soreness (DOMS) early in the morning. The CR-10 Borg's scale was also used for monitoring the rate of perceived exertion (RPE) of players after training sessions. Repeated-measures analysis of variance was executed to test the between-week variations of both well-being and training intensity outcomes. Moreover, Pearson product moment correlation was used to test the relations between well-being and training intensity outcomes. Repeated measures ANOVA revealed significant differences between weeks in the sleep quality (F = 0.422; p &lt; 0.001; ηp2 = 0.140), readiness (F = 0.8.734; p &lt; 0.001; ηp2 = 0.251), fatigue (F = 4.484; p &lt; 0.001; ηp2 = 0.147), DOMS (F = 3.775; p = 0.001; ηp2 = 0.127), RPE (F = 7.301; p &lt; 0.001; ηp2 = 0.219), and session-RPE (F = 17.708; p &lt; 0.001; ηp2 = 0.405). Correlations between well-being and training intensity outcomes in the same week revealed moderate correlations between fatigue and session-RPE (r = 0.325). As conclusions, it was found that well-being and training intensity fluctuates over the season, while well-being outcomes seems to be related with training intensity, although with a small magnitude.



#16 Fitness, Fatness, and Academic Attainment in Male Schoolchildren from a Soccer Academy

Reference: Int J Environ Res Public Health. 2022 Mar 6;19(5):3106. doi: 10.3390/ijerph19053106.

Authors: Souhail Hermassi, Thomas Bartels, Lawrence D Hayes, René Schwesig

Summary: This investigation explored the association between anthropometric measures, fitness, and academic attainment (mathematics and science grade point average [GPA]) in male schoolchildren from a soccer academy. Thirty-one males (age: 10.3 ± 1.19 years; body mass: 41.7 ± 6.5 kg; height: 1.43 ± 0.07 m; body mass index (BMI): 20.2 ± 2.8 kg/m2) participated. Body mass, body fat percentage (%BF), and BMI were used as measures of anthropometry. The Yo-Yo Intermittent Recovery Test (level 1), squat and counter-movement jumps (SJ and CMJ), static balance, 10 and 15 m sprint, and a T-half test for change-of-direction (CoD) performance were used to measure fitness parameters. The GPA of mathematics and science determined academic attainment. All physical performance tests showed excellent relative reliability. ICC was between 0.87 (10 m sprint) and 1.00 (15 m sprint, CMJ). Regarding correlations between fatness and academic attainment, we found three correlations of practical value (r &gt; 0.5), but only for mathematics (BMI: r = 0.540, subscapular skinfold: r = 0.589, body fat: r = 0.560). Mathematics was relevantly correlated with 15 m sprint (r = 0.574) and Yo-Yo IR1 test (r = 0.770). Only static balance (r = 0.428) did not reach the relevance criteria (r &gt; 0.5). Science only showed large correlations with static balance (r = 0.620) and Yo-Yo IR1 test (r = 0.730). In conclusion, fatness and fitness are related to academic attainment in schoolchildren. In addition, except for static balance, all physical performance parameters were relevantly (r &gt; 0.5) correlated with mathematics.



#17 Fitness, Fatness, and Academic Attainment in Male Schoolchildren from a Soccer Academy

Reference: Int J Environ Res Public Health. 2022 Mar 6;19(5):3106. doi: 10.3390/ijerph19053106.

Authors: Souhail Hermassi, Thomas Bartels, Lawrence D Hayes, René Schwesig

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Summary: This investigation explored the association between anthropometric measures, fitness, and academic attainment (mathematics and science grade point average [GPA]) in male schoolchildren from a soccer academy. Thirty-one males (age: 10.3 ± 1.19 years; body mass: 41.7 ± 6.5 kg; height: 1.43 ± 0.07 m; body mass index (BMI): 20.2 ± 2.8 kg/m2) participated. Body mass, body fat percentage (%BF), and BMI were used as measures of anthropometry. The Yo-Yo Intermittent Recovery Test (level 1), squat and counter-movement jumps (SJ and CMJ), static balance, 10 and 15 m sprint, and a T-half test for change-of-direction (CoD) performance were used to measure fitness parameters. The GPA of mathematics and science determined academic attainment. All physical performance tests showed excellent relative reliability. ICC was between 0.87 (10 m sprint) and 1.00 (15 m sprint, CMJ). Regarding correlations between fatness and academic attainment, we found three correlations of practical value (r &gt; 0.5), but only for mathematics (BMI: r = 0.540, subscapular skinfold: r = 0.589, body fat: r = 0.560). Mathematics was relevantly correlated with 15 m sprint (r = 0.574) and Yo-Yo IR1 test (r = 0.770). Only static balance (r = 0.428) did not reach the relevance criteria (r &gt; 0.5). Science only showed large correlations with static balance (r = 0.620) and Yo-Yo IR1 test (r = 0.730). In conclusion, fatness and fitness are related to academic attainment in schoolchildren. In addition, except for static balance, all physical performance parameters were relevantly (r &gt; 0.5) correlated with mathematics.



#18 The Uptake of Nordic Hamstring Exercise Program for Injury Prevention in Major League Soccer and Its Barriers to Implementation in Practice

Reference: J Sport Rehabil. 2022 Mar 10;1-6. doi: 10.1123/jsr.2021-0262. Online ahead of print.

Authors: Paul Chesterton, Garrison Draper, Matthew Portas, Craig Tears

Summary: It is well demonstrated that Nordic hamstring (NH) program has poor compliance across European soccer clubs, but little is known about its implementation in Major League Soccer (MLS). The authors aimed to investigate MLS hamstring prevention practices and compliance with the NH program and understand the reasons for its inclusion or exclusion. A cross-sectional electronic survey was completed by 24 of the 26 (92%) MLS top-division soccer clubs. The survey, based on the Reach, Efficacy, Adoption, Implementation, and Maintenance framework, was sent to team medical staff. Medical staff were also asked for opinions on barriers to implementation. Eighteen clubs (75%) reported a formal hamstring injury prevention program, with eccentric exercises (94%; 95% CI [confidence interval], 74%-99%), high-speed running (94%; 95% CI, 74%-99%), and NH exercises (89%; 95% CI, 67%-97%) the most common strategies adopted. Fifteen clubs partially implemented the NH program, but only 5 (21%; 95% CI, 9%-40%) completed the full program and were classed as compliant. A total of 20 respondents reported that player perception and muscle soreness (83%; 95% CI, 64%-93%) were barriers to the implementation of the NH program. On a 5-point Likert scale, respondents "partially agreed" (4.13 [0.80]) that the NH exercise could substantially reduce injuries and would be "effective" at their own club (3.88 [0.61]). The NH exercise was valued, but negative player perception and muscular soreness were identified as barriers to implementing the full program. Manipulation of volume and frequency should inform future "effectiveness" research to prospectively assess such modifications in the context of MLS.



#19 High-speed training in a specific context in soccer: transition games

Reference: Int J Sports Med. 2022 Mar 10. doi: 10.1055/a-1794-9567. Online ahead of print.

Authors: Jose Asian-Clemente, Alberto Rabano-Munoz, Bernardo Requena, Luis Suarez-Arrones

Summary: The aims of this study were to compare the load of three tasks designed to train features of soccer: a transition game, a small-sided game with a change of playing area, and a large-sided game. Twenty young elite players performed these tasks. Variables measured were total distance covered (DC), distance covered at 14.0-17.9 km·h-1 (DC 14.0-17.9 km·h-1), distance covered at 18.0-21 km·h-1 (DC 18-21 km·h-1), distance covered at >21 km·h-1 (DC >21 km·h-1), peak speed, accelerations and decelerations >1.0 and >2.5 m·s-2, player load, and rate of perceived exertion. Transition games produced greater DC 18-21 km·h-1, DC >21 km·h-1, peak speed and Acc >2.5 m·s-2 than the other drills (p<0.01) and higher DC 14-17.9 km·h-1 (p<0.01), Dec >1 m·s-2 (p<0.05) and Dec >2.5 m·s-2 (p<0.01) than the large-sided game. Both sided games produced more DC (p<0.01), Acc >1 m·s-2 (p<0.01) and player load (p<0.01 and p<0.05, respectively) than the transition game. During the small-sided game, significantly higher DC 14-17.9 km·h-1, DC 18-21 km·h-1 and DC >21 km·h-1 were recorded in comparison with the large-sided game (p<0.01). The studied parameters showed lower variation in the transition game. Coaches could use transition games to train high speed running in counter-attack contexts.



#20 The impact of COVID-19 lockdown on soccer positional and physical demands in the Spanish La Liga

Reference: Sci Med Footb. 2022 Mar 18. doi: 10.1080/24733938.2022.2055784. Online ahead of print.

Authors: Tomás García-Calvo, Javier Fernandez-Navarro, Jesús Díaz-García, Roberto López-Del Campo, Fermín Martínez Fernández, Daniel Memmert

Summary: The present study aimed to analyse the playing surface area, dispersion and distance covered of professional football teams comparing the pre-lockdown and the post- lockdown periods. Positional and match physical demands data were collected from all matches played in the First Spanish Division (n = 760) during season 2019/2020. Pre-lockdown (1st - 27th matchday) and post-lockdown period (28th - 38th matchday) were compared. Variables related to team-level spatial (i.e., convex hull, team width and team length) and physical performance (i.e., total distance and high-speed running distance) were analysed using an optical tracking system (i.e., ChyronHego). In addition, these variables were concerning in respect to the match location contextual variable. Linear mixed models were used to examine the difference between the pre-lockdown and post- lockdown periods following a hierarchical structure considering players, matches and teams. The results revealed that the pandemic lockdown affected the teams' performance when comparing the periods before and after lockdown, showing a general decrease in the average values of the spatial and physical variables measured. The current data could assist practitioners in making informed decisions in order to design and improve training plans for similar situations in which teams return to competition after an unusual period with no training.



#21 An audit of performance nutrition services in English soccer academies: implications for optimising player development

Reference: Sci Med Footb. 2022 Mar 21;1-11. doi: 10.1080/24733938.2022.2055785. Online ahead of print.

Authors: Daniel J Carney, Marcus P Hannon, Nicholas M Coleman, Rebecca C Murphy, Graeme L Close, James P Morton

Summary: To audit the current provision of performance nutrition services provided to male adolescent players within academies from the English soccer leagues. Practitioners from all 89 academies (status categorised as one-four according to the Elite Player Performance Plan, EPPP) completed an online survey to audit: a) job role/professional accreditation status of persons delivering nutrition support, b) activities inherent to service provision, c) topics of education, d) on-site food, fluid and supplement provision and e) nutritional related data collected for objective monitoring. More full-time accredited nutritionists are employed within category one (14/26) versus category two (0/18), three (1/41) and four (0/4). Respondents from category one clubs report more hours of monthly service delivery (62 ± 57 h) than category two (12 ± 9 h), three (14 ± 26 h) and four (12 ± 14 h), inclusive of one-to-one player support and stakeholder education programmes. Category one practitioners reported a greater prevalence of on-site food, fluid and supplement provision on training and match days. Across all categories, players from the professional development phase receive more frequent support than players from the youth development phase, despite the latter corresponding to the most rapid phase of growth and maturation. We report distinct differences in the extent of service provision provided between categories. Additionally, players from all categories receive nutrition support from non-specialist staff. Data demonstrate that performance nutrition appears an under-resourced component of academy sport science and medicine programmes in England, despite being an integral component of player development.



#22 Return to Play and Player Performance After Foot Fracture in UEFA Soccer Players

Reference: Orthop J Sports Med. 2022 Mar 11;10(3):23259671221078308. doi: 10.1177/23259671221078308. eCollection 2022 Mar.

Authors: Connor C Diaz, Ophelie Z Lavoie-Gagne, Avinaash Korrapati, Nalin S John, Mariah I Diaz, Enrico M Forlenza, Nicholas A Trasolini, Brian Forsythe

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Summary: There is a paucity of information on rate and time to return to play (RTP) in elite-level soccer players who have sustained foot fractures. The purpose was to (1) determine the rate and timing of RTP after foot fracture (eg, tarsal, metatarsal, or phalangeal), (2) investigate foot fracture reinjury incidence after RTP, and (3) evaluate performance after foot fracture as compared with matched, uninjured controls. Athletes sustaining foot fractures were identified across the 5 major European soccer leagues (English Premier League, Bundesliga, La Liga, Ligue 1, and Serie A) between 2000 and 2016. Injured athletes were matched to controls (1:1) using demographic characteristics and performance metrics from 1 season before injury. The authors recorded RTP rate, reinjury incidence, player characteristics associated with RTP within 2 seasons of injury, player availability, field time, and performance metrics during the 4 seasons after injury. A total of 192 elite soccer players sustaining a foot fracture were identified; 40 players (20.8%) underwent operative treatment. Athletes missed an average of 69.41 ± 59.43 days and 5.15 ± 23.28 games. In the 4 seasons after injury, 80% of players returned to play, with 72% returning to play within 1 season of injury. Nine players (5%) sustained a subsequent foot fracture. Athletes with a foot fracture demonstrated significantly longer league retention compared with uninjured controls (P < .001). Elite soccer players older than 30 years of age were less likely to RTP (odds ratio, 0.67; P = .002), whereas career experience, field position, and baseline performance showed no significant association with RTP rates. Injured athletes demonstrated similar performance to controls during the 4 years after injury, and there were no position-dependent differences on subgroup analysis. The players who underwent operative treatment had more assists per 90 minutes and more team points per game during the first season after injury compared with athletes treated nonoperatively. Foot fractures in elite soccer players resulted in moderate loss of play time (69.41 days). RTP rates were high at 80%, although players older than 30 years of age were less likely to RTP. On RTP, athletes who sustained a foot fracture maintained performance similar to preinjury levels and to uninjured controls.


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