Latest research in football - week 6 - 2023

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 High-intensity circuit training change serum myostatin but not myogenin in adolescents' soccer players: a quasi-experimental study

Reference: BMC Sports Sci Med Rehabil. 2023 Feb 6;15(1):15. doi: 10.1186/s13102-023-00627-1.

Authors: Amirhosein Ziyaiyan, Mohammadreza Kordi, Martin Hofmeister, Karim Chamari, Wassim Moalla, Abbas Ali Gaeini

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Summary: Skeletal muscle contractions due to exercise lead to the secretion of many proteins and proteoglycan peptides called myokines. Myostatin (MSTN) and Myogenin (MyoG) are two of the most important skeletal muscle growth regulatory factors related to myoblast differentiation and muscle hypertrophy. The present study aims at investigating the effects over eight weeks of high-intensity circuit training (HICT) on serum MyoG and MSTN in male soccer players. The present study is a quasi-experimental study on 21 male soccer players (Experimental group: n = 11, Control group: n = 10) (ages 15.0 ± 3.4 years, body mass 55.7 ± 7.8 kg, height 173.3 ± 8.0 cm, Body mass index 18.4 ± 1.9 kg m-2, maximum oxygen uptake 61.89 ± 3.01 ml kg-1 and the peak height velocity 14.5 ± 0.3 years). Participants were randomly divided into two groups: training group and a control group. The first resting blood samples were obtained in the morning-fasting state, and the second blood samples were obtained after the maximum aerobic test at pre- and post-HICT. There were non-significant differences in resting serum values of MyoG (p = 0.309, p > 0.05) but significant differences in resting serum values of MSTN between the training and control groups after eight weeks of HICT (p = 0.003, p < 0.05). No significant differences were observed between groups in the acute response of serum values of MyoG (p = 0.413, p < 0.05) and MSTN (p = 0.465, p < 0.05) to the maximum aerobic test after eight weeks of HICT. These results suggest that eight weeks of HICT can decrease the resting serum values of MSTN but not change the resting serum values of MyoG in male adolescent soccer players. Also, eight weeks of HICT does not affect the acute response of MSTN and MyoG after a maximum aerobic test.



#2 Cortical thickness and neurocognitive performance in former high-level female soccer and non-contact sport athletes

Reference: Scand J Med Sci Sports. 2023 Feb 6. doi: 10.1111/sms.14324. Online ahead of print.

Authors: Franziska Katharina Haase, Annika Prien, Linda Douw, Nina Feddermann-Demont, Astrid Junge, Claus Reinsberger

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Summary: Long-term effects of playing soccer (football) on the brain structure and function of the brain are vividly debated. While some studies showed differences in neurocognitive performance and structural brain changes in retired male players, data on female players are scarce. The present study compares cortical thickness and neurocognitive performance in former high-level female soccer (SOC) and non-contact sport athletes (CON). 3T T1-weighted 3D MPRAGE MRI was performed and vertex-wise cortical thickness was analyzed using FreeSurfer (v. 6.0.0). Neurocognitive performance in seven domains of SOC and CON was assessed. A multivariate linear model was used to analyze interactions with respect to heading frequency and a history of concussion. SOC (n=15, mean age 38.3 ± 5.1 years) and CON (n=16, mean age 36.6 ± 5.8 years) had a similar cortical thickness and performed similarly in the neurocognitive tests except for verbal memory and psychomotor speed, where SOC performed significantly worse than CON. Moderate headers had a significantly larger cortical thickness than rare headers in the right inferior parietal region. Visual memory and cortical thickness were positively correlated in the group of frequent headers and negatively correlated in CON, but not in the other header groups. In contrast to previous reports in male football players, female players did not reveal cortical thinning in comparison to control athletes, whereas neurocognitive profiles of female football players might not significantly differ from male athletes. Small sample sizes, subjective header assessment and the case-control study design require a cautious interpretation.



#3 'Football and dancing are in our blood': culture promoting sports practice among immigrants in Europe

Reference: Health Promot Int. 2023 Feb 1;38(1):daac202. doi: 10.1093/heapro/daac202.

Authors: Sílvia Monserrate-Gómez, Lourdes Rubio-Rico, Roser Cuesta-Martínez, Rosa-Dolors Raventós-Torner, Alba Roca-Biosca, Inmaculada de Molina-Fernández

Summary: The current state of knowledge indicates that regular sports practice helps prevent and treat non-communicable diseases. The promotion of sport is, therefore, an important community health intervention for maintaining and improving the health of individuals and populations. Culture is identified as being associated with sports practice and sedentary behaviour of ethnic and national minorities. This study aims qualitatively to analyse the potential for culture as a basis for the promotion of sport among immigrants in four regions of Mediterranean Europe. Ten focus groups (n = 62) were conducted with immigrants-adults and young people over the age of 11-and people involved in promoting sport. Thematic content analysis was conducted. The results enabled identifying two major issues: sport as a vehicle for cultural expression and synergies between sport and culture. Accordingly, sport serves to express global, local and non-ethno-national cultural belonging. Regarding synergies, culture and sport feed each other positively and contribute to immigrants' health and cultural well-being. Culture as a strategy for promoting sports practice requires an interdisciplinary approach that involves collaboration between healthcare practitioners and social sciences professionals. There is also a need to use the various axes of cultural definition-global, local and non-ethno-national-of those involved, and for them to take part themselves in designing sports activities. Moreover, promoting sport through non-ethno-national axes of cultural definition may help with immigrants' social inclusion, as intercultural relations between migrants and newcomers are promoted.



#4 The England football team is better managed than the country's health policy

Reference: BMJ. 2022 Dec 7;379:o2953. doi: 10.1136/bmj.o2953.

Authors: Nason Maani, Martin McKee

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#5 Changes After a Conventional vs. an Alternative Therapy Program on Physical, Psychological, and Injury-Related Parameters in Male Youth Soccer Players With Patellar Tendinopathy During Return to Competition

Reference: J Strength Cond Res. 2023 Feb 7. doi: 10.1519/JSC.0000000000004467. Online ahead of print.

Authors: Marc Niering, Thomas Muehlbauer

Summary: Changes after a conventional (CON) vs. alternative (ALT) therapy program on physical, psychological, and injury-related or pain-related parameters in soccer players with patellar tendinopathy (PT) during return to competition were examined. Thirty-four male youth soccer players (15-16 years) with PT were randomly assigned to a CON (n = 18) or ALT (n = 16) program. The ALT program consisted of 60 minutes of balance training, eccentric and isometric exercises, static stretching, and a dual-task progression. The CON program consisted of 30 minutes of eccentric and isometric exercises and static stretching. Both programs were conducted until painlessness was reported during full training load. Assessments of muscle power (drop jump, jump and reach), change of direction speed (CODS) (acyclic sprint), speed (tapping, 30-m linear sprint), endurance (Yo-Yo intermittent recovery test level-1), the Achievement Motives Scale Sport, and injury-related or pain-related correlates were performed immediately, 6 weeks, 16 weeks, and 20 weeks after the respective therapy program. Players in the ALT group required a shorter program duration (ALT: 47.1 ± 15.6 days, CON: 58.2 ± 24.6 days) and achieved the same (muscle power, speed, endurance) or greater (CODS) improvements in physical performances, the same enhancements in psychological measures (achievement motives), and better values for injury-related or pain-related correlates (injury incidence, pain-related training interruptions). Results indicate that both programs effectively improve relevant outcome parameters in players with PT. The ALT therapy is more time efficient than the CON therapy. Therapists should consider this multimodal training program for effective treatment of athletes to shorten their return to competition time and minimize the risk of secondary injuries.



#6 The incidence of anterior cruciate ligament injury in youth and male soccer athletes: an evaluation of 17,108 players over two consecutive seasons with an age-based sub-analysis

Reference: Knee Surg Sports Traumatol Arthrosc. 2023 Feb 13. doi: 10.1007/s00167-023-07331-0.

Authors: Diego Costa Astur, Gabriel Furlan Margato, Alexandre Zobiole, Diego Pires, Luis Fernando Zucanovic Funchal, Andrew Esteban Jimenez, Eduardo Vasconcelos Freitas, Moises Cohen

Summary: The aim was to evaluate the incidence of anterior cruciate ligament (ACL) injuries in male athletes from professional soccer clubs over two consecutive seasons (2018-2019) with a sub-analysis based on age category: under-13 (U-13), under-15 (U-15), under-17 (U-17), and under-20 (U-20) years. A total of 17,108 young male soccer players were retrospectively reviewed from sixty-three professional clubs in the four highest Brazilian soccer divisions. Data regarding the number of athletes and the number of ACL injuries confirmed by magnetic resonance imaging (MRI) exams in the 2018 and 2019 seasons were collected. Incidence of ACL injury were compared by season, age category (under-13; under-15; under 17; and under-20), demographic region, and club division. Clubs from all regions of Brazil participated in the study. A total of 336 primary ACL injuries were diagnosed over the two seasons (8,167 athletes during the 2018 season and 8,941 athletes during the 2019 season) among all athletes, which corresponds to 2% of the included athletes. There were 11 cases (0.3%) in the under-13, 53 cases (1.3%) in the under-15, 107 cases (2.5%) in the under-17, and 165 cases (3.8%) in the under-20 age category. There was a higher incidence of ACL injury in the older age groups (p < 0.001). A total of 336 ACL injuries were identified in 17,108 youth soccer players from 63 professional clubs with an overall incidence of 2% over 2 seasons of competition. ACL injury rate ranged from 0.3% to 3.8% and was higher in the older and more competitive club divisions.



#7 Collagen supplementation augments changes in patellar tendon properties in female soccer players

Reference: Front Physiol. 2023 Jan 26;14:1089971. doi: 10.3389/fphys.2023.1089971. eCollection 2023.

Authors: Joonsung Lee, Josh E Bridge, David R Clark, Claire E Stewart, Robert M Erskine

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Summary: We investigated the effect of collagen hydrolysate supplementation on changes in patellar tendon (PT) properties after 10 weeks' training in female soccer players from a Football Association Women's Super League Under 21 s squad. We pair-matched n = 17 players (age: 17 ± 0.9 years; height: 1.66 ± 0.06 m; mass: 58.8 ± 8.1 kg) for baseline knee extension (KE) maximum isometric voluntary contraction (MIVC) torque, age, height, and body mass, and randomly assigned them to collagen (COL) or placebo (PLA) groups (COL n = 8, PLA n = 9). Participants consumed 30 g collagen hydrolysate supplementation or energy-matched PLA (36.5 g maltodextrin, 8.4 g fructose) and plus both groups consumed 500 mg vitamin C, after each training session, which comprised bodyweight strength-, plyometric- and/or pitch-based exercise 3 days/week for 10 weeks in-season. We assessed KE MIVC torque, vastus lateralis muscle thickness and PT properties using isokinetic dynamometry and ultrasonography before and after 10 weeks' soccer training. KE MIVC torque, muscle thickness and tendon cross-sectional area did not change after training in either group. However, COL increased PT stiffness [COL, +18.0 ± 12.2% (d = 1.11) vs. PLA, +5.1 ± 10.4% (d = 0.23), p = 0.049] and Young's modulus [COL, +17.3 ± 11.9% (d = 1.21) vs. PLA, +4.8 ± 10.3% (d = 0.23), p = 0.035] more than PLA. Thus, 10 weeks' in-season soccer training with COL increased PT mechanical and material properties more than soccer training alone in high-level female soccer players. Future studies should investigate if collagen hydrolysate supplementation can improve specific aspects of female soccer performance requiring rapid transference of force, and if it can help mitigate injury risk in this under-researched population.



#8 Movement retraining programme in young soccer and rugby football players: A feasibility and proof of concept study

Reference: J Bodyw Mov Ther. 2023 Jan;33:28-38. doi: 10.1016/j.jbmt.2022.09.017. Epub 2022 Sep 30.

Authors: Paolo Dainese, Nadine Booysen, Anna Mulasso, Mattia Roppolo, Maria Stokes

Summary: Movement screening to identify abnormal movement patterns can inform development of effective interventions. The primary objective of this study was to evaluate the feasibility of using a movement screening tool in combination with a tailored movement control retraining programme in young soccer and rugby football players. A secondary objective was to investigate changes in movement control patterns post-intervention, to provide proof of concept (PoC) for movement retraining. 52 male amateur players, including 34 soccer players (mean age 15 ± 2 years) and 18 rugby players (mean age 15 ± 1 years) participated. They were screened for movement control ability using a shortened version of the Hip and Lower Limb Movement Screening (Short-HLLMS) and completed an eight-week movement control retraining programme. Evaluation of feasibility included consent from players invited, adherence, attendance at the exercise sessions, drop-out and adverse events. Short-HLLMS total score and The Copenhagen Hip and Groin Outcome Score (HAGOS) were analysed to provide PoC for retraining movement control. Feasibility outcomes were favourable. Significant statistical changes occurred post-intervention in the Short-HLLMS total score (paired-samples t-test) and in three HAGOS subscales (symptoms, physical function in daily living and in sport and recreation) (Wilcoxon-Signed Rank Test) in both groups. Feasibility of using the Short-HLLMS in combination with a movement control retraining programme in soccer and rugby players was promising. The data provided PoC for the potential application of a shortened version of the HLLMS to evaluate changes in movement control and to inform targeted motor control programmes.



#9 Curcumin Attenuates Delayed-Onset Muscle Soreness and Muscle Function Deficits Following a Soccer Match in Male Professional Soccer Players

Reference: Int J Sports Physiol Perform. 2023 Jan 1;1-7. doi: 10.1123/ijspp.2022-0283. Online ahead of print.

Authors: William Abbott, Emily J Hansell, Adam Brett, Jakob Škarabot, Lewis J James, Tom Clifford

Summary: The aim was to examine the effects of acute curcumin (CURC) supplementation on recovery from a soccer match in male professional players. In a randomized, placebo-controlled, crossover design, 11 players from the under-23 team of an English Premier League club (age 19 [1] y, body mass 79.4 [7.9] kg, height 180.8 [5.7] cm) consumed 500 mg of CURC or a control (medium-chain triglycerides) immediately and 12 and 36 hours after a 90-minute match. Countermovement jump height (CMJ), reactive strength index (RSI), delayed-onset muscle soreness (DOMS, 0-200 mm), and subjective well-being were measured before and 12, 36, and 60 hours postmatch. Global positioning systems measured external load during matches, and dietary intake was recorded across the testing period. External load and dietary intake did not differ between conditions (P ≥ .246). CURC attenuated deficits in CMJ (P ≤ .004) and RSI (P ≤ .001) and reduced DOMS (P ≤ .004) at all postmatch time points (except 60 h post for RSI). The greatest difference between control and CURC was 12 hours post for CMJ (P < .001, 1.91 [4.40] cm, 95% CI, 1.25 to 2.57, g = 0.36) and RSI (P = .003, 0.40 [0.41] AU, 95% CI, 0.17 to 0.63, g = 0.90) and 36 hours post for DOMS (P < .001, 47 [23] mm, 95% CI, -67 to -27, g = 2.12). CURC intake <36 hours after a soccer match attenuated DOMS and muscle function deficits, suggesting that CURC may aid recovery in professional male soccer players.



#10 Adding A Structured Educational Session to the Rehabilitation Program of Soccer Players Following Anterior Cruciate Ligament Reconstruction: A Feasibility Study

Reference: Int J Sports Phys Ther. 2023 Feb 1;18(1):81-91. doi: 10.26603/001c.68141. eCollection 2023.

Authors: Abdullah Almuhaya, Ali Albarrati, Ahmed Alhowimel, Faris Alodaibi

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Summary: While a lack of psychological preparedness and fear of movement may be linked with the anterior cruciate ligament (ACL) re-injury, these variables are rarely addressed throughout the therapy stages via educational sessions. Unfortunately, in terms of reducing fear, increasing function, and returning to play, no research has been done yet on the efficacy of adding organized educational sessions to the rehabilitation programs of soccer players post-ACL reconstruction (ACLR). Therefore, the study's aim was to assess the feasibility and acceptability of adding organized educational sessions to the rehabilitation programs post-ACLR. A feasibility randomized controlled trial (RCT) was conducted in a specialized sports rehabilitation center. Participants post ACL reconstruction were randomized to either usual care with a structured educational session (intervention group) or usual care alone (control group). This feasibility study investigated three aspects: recruitment, intervention acceptability and randomization, and retention. The outcome measures included Tampa Scale of Kinesiophobia, ACL-Return to Sport after Injury, and International Knee Documentation Committee for knee function. Measurements were done at baseline and one week after the intervention. All of the 36 players who were undergoing rehabilitation post-ACLR at the center at the time of the study were invited to participate in the study. Thirty-five players (97.2%) agreed to participate in the study. The participants responded to some questions about the acceptability of the intervention and randomization and most of them thought they were appropriate. 30 (85.7%) participants completed the follow-up questionnaires one week after the randomization. This feasibility research found that adding a structured educational session to the rehabilitation program for soccer players after ACLR is feasible and acceptable. Full-scale RCTs with longer follow-ups and multiple locations are recommended.



#11 Sex Differences in Copper Concentrations during a Sports Season in Soccer Players

Reference: Nutrients. 2023 Jan 18;15(3):495. doi: 10.3390/nu15030495.

Authors: Víctor Toro-Román, Diego Muñoz, Marcos Maynar-Mariño, Sara Clemente-Gil, María C Robles-Gil

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Summary: Physical training produces changes in the concentrations of trace mineral elements. Sex differences in copper (Cu) concentrations in athletes are scarce. The objectives of this study were (i) to analyze changes in intracellular (erythrocytes and platelets) and extracellular (plasma and urine) Cu concentrations during a sports season in soccer players and (ii) to analyze sex differences. A total of 46 soccer players (22 men and 24 women) participated in the study. Three assessments were performed throughout the sports season. Anthropometry, body composition, nutritional intake, physical condition, female hormones (menstrual cycle) and hematology were evaluated, as well as Cu determination (plasma, urine, erythrocytes, and platelets). Regarding longitudinal differences, there were discrepancies in plasma, urine, absolute erythrocyte, and absolute platelet Cu concentrations (p < 0.05). There were differences between sexes in Cu concentrations in urine, erythrocytes relative to cell number and in platelets relative to cell number (p < 0.05). During a sports season, there are changes in Cu concentrations in soccer players. Likewise, there could be sex differences in urinary, erythrocyte and platelet Cu concentrations.



#12 Weekly variations of accelerometer variables and workload of professional soccer players from different positions throughout a season

Reference: Sci Rep. 2023 Feb 14;13(1):2625. doi: 10.1038/s41598-023-29793-5.

Authors: Hadi Nobari, Gibson Moreira Praça, Sarah da Glória Teles Bredt, Pablo Prieto González, Filipe Manuel Clemente, Jorge Carlos-Vivas, Luca Paolo Ardigò

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Summary: The current study aimed to analyze, using accelerometer-based activity, acute workload, chronic workload, acutechronic workloads ratio, training-monotony and training-strain throughout a competitive soccer-season and to compare these variables between players from different playing positions. Twenty-one professional soccer-players were monitored during the 48 weeks of the season. Players were grouped according to their position. Four lateral-defenders and four winger-players formed LDW group, four central-defenders and four forwards formed CDF group, and six midfielder-players formed MDF group. Accelerometer-based variables were collected during training and match contexts and were used to generate indicators of weekly acute and chronic workload, training monotony, training strain and metabolic power. A one-way ANOVA compared all dependent variables between groups, and effect sizes for pairwise comparisons were calculated. Results revealed variations in the weekly load throughout the season, which demands caution from coaches to avoid injuries. There were no differences in weekly-loads for all dependent variables (P > 0.05, small-to-moderate effects). We conclude that the weekly-load is not constant during a competitive season and players from different positions have similar weekly-loads. Therefore, previously reported in the literature, possible match-related positional differences might be compensated by differences in training-related loads, leading to a similar profile when considering the whole week.



#13 The Influence of Pitch Dimensions during Small-Sided Games to Reach Match Physical and Physiological Demands on the Youth Soccer Players

Reference: Sensors (Basel). 2023 Jan 23;23(3):1299. doi: 10.3390/s23031299.

Authors: Alfonso Castillo-Rodríguez, Álvaro Durán-Salas, Jesús Vicente Giménez, Wanesa Onetti-Onetti, Luis Suárez-Arrones

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Summary: The aims of this study were to (i) analyze the physical and physiological responses of four matches competition and (ii) to investigate the relationships among three different pitch dimensions of small-sided game (SSG) on the youth soccer players. Fifteen male U19 soccer players (age 17.3 ± 0.5 years, height 175.7 ± 5.6 cm, weight 68.5 ± 8.6 kg, playing experience 7.8 ± 1.4 years) were randomly assigned to three play areas: small (50 m2), medium (SSG-m, 150 m2) and large (SSG-l, 250 m2) area per player including goalkeeper. During the 4-week intervention, both groups performed three sets of 8 min with a passive rest period of 5 min between games. Differences in time-motion characteristics of players were measured with the Global Positioning System and assessed using a repeated measures ANOVA to compare the three game conditions and the magnitude-based inference to evaluate the pairwise comparison effects. The results showed that only the variables distance covered between 7.0-12.9 km·h-1 was not statistically significantly different among game conditions (p < 0.05; η = 0.21; small) and physiological response (i.e., hear rate of playing time spent 85-89% HRmax) also showed differences (p < 0.05; η = 0.25; small). The responses in SSG-m and SSG-l established them ass the format sizes ideal for replicating the physical responses during match competition. These findings could provide relevant information for coaches for use adequate pitch size (areas of 150 m2 and 250 m2) to reach the match-play scenarios found in match competition.



#14 Influence of Scoring Systems on Mental Fatigue, Physical Demands, and Tactical Behavior during Soccer Large-Sided Games

Reference: Int J Environ Res Public Health. 2023 Jan 23;20(3):2087. doi: 10.3390/ijerph20032087.

Authors: Jesús Díaz-García, José Carlos Ponce-Bordón, Abel Moreno-Gil, Ana Rubio-Morales, Miguel Ángel López-Gajardo, Tomás García-Calvo

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Summary: Constraints are common in soccer training to develop physical, technical-tactical, and mental training concurrently. This study examined how different scoring systems influence physical, tactical, and mental demands during large-sided games in soccer. Eighteen youth-elite male (17.39 ± 1.04 y) soccer players completed three 8 vs. 8 large-sided games where the different score systems were i) official score system (OSS; i.e., 1 goal = 1 goal), ii) double the value of the goal-4 min (DVx4; i.e., 1 goal = 1 goal from 0.00 to 7.59 min, and 1 goal = 2 goals from 8.00 to 12.00 min), and iii) double the value of the goal-8 min (DVx8; i.e., 1 goal = 1 goal from 0.00 to 3.59 min, and 1 goal = 2 goals from 4.00 to 12.00 min). Physical demands and tactical behaviors were recorded during tasks using a global positioning system and video camera. Mental fatigue was recorded pre- and post-task using a visual analogue scale. Also, the ratio of perceived exertion and mental load were recorded after tasks were finished. Results reported the highest values of mental and physical demands in DVx4. Mental fatigue increased during all three large-sided games, although this increase was significantly higher in DVx4 compared with OSS (p = 0.006) and DVx8 (p = 0.027). Tactical behavior showed a trend towards more direct play during DVx4, which was less observed during DVx8, and not at all during OSS. In conclusion, changing the scoring system affects physical, tactical, and mental demands.



#15 Age and Maturation Matter in Youth Elite Soccer, but Depending on Competitive Level and Gender

Reference: Int J Environ Res Public Health. 2023 Jan 21;20(3):2015. doi: 10.3390/ijerph20032015.

Authors: Honorato J Ginés, Florentino Huertas, Tomás García Calvo, Jose Carlos Ponce-Bordón, António J Figueiredo, Rafael Ballester

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Summary: This study aimed to explore the relevance of the relative age effect (RAE), maturity status and anthropometry, and their influence on coaches' assessment of players' performance, analyzing both genders and different types of academies (elite vs. non-elite). The sample included 603 soccer players (385 male), from the under 12 (U12), under 14 (U14) and under 16 (U16) categories, belonging to elite and nonelite teams. Coaches' assessment of players' performance, chronological age, anthropometric characteristics, maturity offset (MO) and peak height velocity (PHV) were registered. Our results showed that RAE was present in both genders within the elite, but not in the nonelite academies. Early maturity players were overrepresented in the male elite, but not in the female academies. No relationship was found between RAE and anthropometry in male elite academies. Male elite players showed better anthropometric characteristics than nonelite players, while this pattern of results was not found for female players. The coaches' assessment on players' current performance was not influenced by the chronological age nor anthropometry, but it was linked to the PHV. Coaches from nonelite academies rated better in current assessment of performance the taller players. Our findings suggest that maturity status and RAE play an independent and important role in the talent selection process.



#16 How Different Predominant SARS-CoV-2 Variants of Concern Affected Clinical Patterns and Performances of Infected Professional Players during Two Soccer Seasons: An Observational Study from Split, Croatia

Reference: Int J Environ Res Public Health. 2023 Jan 20;20(3):1950. doi: 10.3390/ijerph20031950.

Authors: Jasna Nincevic, Anamarija Jurcev-Savicevic, Sime Versic, Toni Modric, Ante Turic, Ante Bandalovic, Boris Becir, Marijana Mijakovic, Ivana Bocina, Damir Sekulic

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Summary: There are limited data describing clinical patterns and match running performance (MRP) among players with COVID-19 infection before and after infection, particularly related to different predominant SARS-CoV-2 variants, as well as in comparison to uninfected players. This observational study was conducted during two consecutive soccer seasons in one professional club in Split, Croatia. There were four clusters of mild, self-limited, or asymptomatic infection characterised by low adherence to preventive measures. Infected players had significantly more symptoms (t-test = 3.24; p = 0.002), a longer period of physical inactivity (χ2 = 10.000; p = 0.006) and a longer period of self-assessment for achieving full fitness (χ2 = 6.744; p = 0.034) in the 2020-2021 season (Wuhan wild strain and Alpha variant) than in the 2021-2022 season (Omicron variant). It was also found that, despite the milder clinical presentation of the infection in the 2021-2022 season, the players had significantly more abnormal laboratory findings (χ2 = 9.069240; p = 0.002), although without clinical significance at the time of the study. As for the MRP, player performance in the 2021-2022 season was not negatively affected by the Omicron variant, while there was an improvement in MRP in scores for a sample of all players. The RTP protocol was correctly applied because it helped the athletes to recover their pre-infection physical capacities relatively quickly. This study advances the understanding that an optimally and individually planned RTP protocol is crucial for the MRP of infected players. Future research needs to replicate the findings of abnormal laboratory results and extend the study focusing on their potential long-term clinical significance.



#17 Characterization of Static Strength, Vertical Jumping, and Isokinetic Strength in Soccer Players According to Age, Competitive Level, and Field Position

Reference: Int J Environ Res Public Health. 2023 Jan 18;20(3):1799. doi: 10.3390/ijerph20031799.

Authors: João Nuno Gouveia, Cíntia França, Francisco Martins, Ricardo Henriques, Marcelo de Maio Nascimento, Andreas Ihle, Hugo Sarmento, Krzysztof Przednowek, Diogo Martinho, Élvio Rúbio Gouveia

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Summary: Muscular strength is strongly related to speed and agility tasks, which have been described as the most decisive actions preceding goals in the soccer game. This study aimed to characterize the players' strength indicators and to analyze the variation associated with age, competition level, and positional role. Eighty-three male soccer players from A team (n = 22), B team (n = 17), U-23 (n = 19), and U-19 (n = 25) participated in this study. Handgrip strength was assessed using a hand dynamometer (Jamar Plus+), countermovement jump (CMJ) and the squat jump (SJ) were evaluated using Optojump Next, and a Biodex System 4 Pro Dynamometer was used to assess the isokinetic strength of knee extension/flexion. Team A players showed increased lower-body strength compared to their peers, mainly through their increased vertical jumping capacity (i.e., CMJ and SJ; ps < 0.019), and superior performance in isokinetic assessments (i.e., peak torque, total work, and average power). Overall, older players outperformed their younger peers regarding vertical jumping, static strength, and average power in isokinetic strength (ps < 0.005). This study emphasizes the superior strength levels of professional soccer players compared with their lower-division peers, even after controlling by age. This information is of great value to sports agents and coaches, underlining the need to design and include strength-specific content during soccer training.



#18 Epidemiology of Injuries in Amateur Male Soccer Players: A Prospective One-Year Study

Reference: Healthcare (Basel). 2023 Jan 25;11(3):352. doi: 10.3390/healthcare11030352.

Authors: Afxentios Kekelekis, Zoe Kounali, Nikolaos Kofotolis, Filipe Manuel Clemente, Eleftherios Kellis

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Summary: The purpose of this study was to prospectively monitor and analyze injuries in Greek amateur male soccer players over one competitive season. One hundred and thirty male soccer players in a regional amateur league participated in this study. Injury data and exposure were collected from six teams during training and competition match over one season (2018/19). Injuries were collected weekly and were classified by setting, mechanism, severity, type, calendar distribution, period of injury occurrence, and anatomical location. A total of 103 injuries were recorded during the season, with an incident rate (IR) of 5.5 injuries/1000 h with 95% confidence intervals (CI) values of 4.45 (lower limit) and 6.09 (upper limit). Furthermore, IR was greater for the posterior thigh (IR 1.83/1000 h, 95% CI 1.21-2.44) and hip/groin complex (IR 1.45/1000 h, 95% CI 0.90-1.99) compared to other anatomical locations. Similarly, muscle injuries had greater IR (IR 3.61/1000 h, 95% CI 2.74-4.47) than other tissues. Amateur soccer players had a seven-fold greater chance of getting injured during games (IR 20.76/1000 h, 95% CI 15.28-26.24) rather than during training (IR 3.077/1000 h, 95% CI 2.16-3.80), while injury rates were higher towards the end of a session and peaked in October and February of the season. Based on these results, amateur soccer may benefit from injury prevention strategies incorporated into their regular training practice and focus on muscle injuries, especially in the posterior thigh and the hip/groin complex.



#19 Use of Exploratory Factor Analysis to Assess the Fitness Performance of Youth Football Players

Reference: J Strength Cond Res. 2023 Feb 13. doi: 10.1519/JSC.0000000000004414. Online ahead of print.

Authors: Fabrizio Perroni, Carlo Castagna, Stefano Amatori, Erica Gobbi, Mario Vetrano, Vincenzo Visco, Laura Guidetti, Carlo Baldari, Marco Bruno Luigi Rocchi, Davide Sisti

Summary: Football performance involves several physical abilities that range in aerobic, anaerobic, and neuromuscular domains; however, little is known about their interplay in profiling individual physical attributes. This study aimed to profile physical performance in youth football players according to their training status. One hundred seven young male soccer players (age 13.5 ± 1.4 years; height 168 ± 7 cm; body mass 57.4 ± 9.6 kg; and body mass index 20.2 ± 2.1 kg·m-2) volunteered for this study. Players' physical performance was assessed with football-relevant field tests for sprinting (10 m sprint), vertical jump (countermovement jump), intermittent high-intensity endurance (Yo-Yo Intermittent Recovery Test Level 1, YYIRT1), and repeated sprint ability (RSA). The training status was assumed as testosterone and cortisol saliva concentrations; biological maturation was estimated using the Pubertal Development Scale. Exploratory factor analysis (EFA) revealed 3 main variables depicting anthropometric (D1, 24.9%), physical performance (D2, 18.8%), and training status (D3, 13.3%), accounting for 57.0% of total variance altogether. The level of significance was set at p ≤ 0.05. The RSA and YYIRT1 performances were largely associated with D2, suggesting the relevance of endurance in youth football. This study revealed that for youth football players, a 3-component model should be considered to evaluate youth soccer players. The EFA approach may help to disclose interindividual differences useful to talent identification and selection.



#20 Commentary: The impact of UEFA Euro 2020 football championship on Takotsubo Syndrome: Results of a multicenter national registry

Reference: Front Cardiovasc Med. 2023 Jan 26;10:1122436. doi: 10.3389/fcvm.2023.1122436. eCollection 2023.

Authors: Francesco Barone-Adesi

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#21 Predicting Injuries in Football Based on Data Collected from GPS-Based Wearable Sensors

Reference: Sensors (Basel). 2023 Jan 20;23(3):1227. doi: 10.3390/s23031227.

Authors: Tomasz Piłka, Bartłomiej Grzelak, Aleksandra Sadurska, Tomasz Górecki, Krzysztof Dyczkowski

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Summary: The growing intensity and frequency of matches in professional football leagues are related to the increasing physical player load. An incorrect training model results in over- or undertraining, which is related to a raised probability of an injury. This research focuses on predicting non-contact lower body injuries coming from over- or undertraining. The purpose of this analysis was to create decision-making models based on data collected during both training and match, which will enable the preparation of a tool to model the load and report the increased risk of injury for a given player in the upcoming microcycle. For this purpose, three decision-making methods were implemented. Rule-based and fuzzy rule-based methods were prepared based on expert understanding. As a machine learning baseline XGBoost algorithm was considered. Taking into account the dataset used containing parameters related to the external load of the player, it is possible to predict the risk of injury with a certain precision, depending on the method used. The most promising results were achieved by the machine learning method XGBoost algorithm (Precision 92.4%, Recall 96.5%, and F1-score 94.4%).



#22 The Assessment of Body Composition and Nutritional Awareness of Football Players According to Age

Reference: Nutrients. 2023 Jan 30;15(3):705. doi: 10.3390/nu15030705.

Authors: Wiktoria Staśkiewicz, Elżbieta Grochowska-Niedworok, Grzegorz Zydek, Mateusz Grajek, Karolina Krupa-Kotara, Agnieszka Białek-Dratwa, Sylwia Jaruga-Sękowska, Oskar Kowalski, Marek Kardas

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Summary: The optimal body composition for health is an individual trait and is determined by genetic factors, sex, age, somatotype, physical activity, and individual variability. The present study aims to assess how professional football players' body composition has changed over the training macrocycle in various age groups and to determine the correlation between nutritional awareness and body composition maintenance. Thirty-eight football players participated in the study, with 16 players classified in the younger age group (19-25) and 22 in the older age group (26-31). Using the direct segmented multi-frequency electrical impedance analysis technique, the athletes' body composition was assessed six times across a training macrocycle made up of preparatory, competitive, and transitional periods. The Sports Nutrition Knowledge Questionnaire was used to evaluate nutrition knowledge. The above correlations show that both younger and older athletes with higher awareness are better able to adjust their nutrition to meet the goals of the preparation period and can achieve greater gains in muscle mass and greater reductions in body fat. According to the study's results, athletes who are better conscious of their nutritional needs during competition experience less muscle loss and exhibit more consistent body weight and BMI levels. Football players' body composition suffers detrimental alterations throughout the transition period. Higher body mass, lean body mass content, and skeletal muscle mass are traits of older players. Higher nutritional knowledge reduces the negative modifications of body composition consisting of muscle mass reduction and fat gain. Nutritional knowledge influences the stability of body composition in both age groups during all the analyzed periods: Preparation, competition, and transition.



#23 The Evaluation of Asymmetry in Isokinetic and Electromyographic Activity (sEMG) of the Knee Flexor and Extensor Muscles in Football Players after ACL Rupture Reconstruction and in the Athletes following Mild Lower-Limb Injuries

Reference: J Clin Med. 2023 Feb 1;12(3):1144. doi: 10.3390/jcm12031144.

Authors: Łukasz Oleksy, Anna Mika, Iwona Sulowska-Daszyk, Renata Kielnar, Zofia Dzięcioł-Anikiej, Joanna Zyznawska, Olga Adamska, Artur Stolarczyk

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Summary: This study was aimed at evaluating knee stabilizer (quadriceps and hamstring) muscle strength and the medio-lateral symmetry of hamstring fatigue in football players after ACL reconstruction and with mild lower extremity injuries. The study comprised 65 professional football players who were divided into three groups: Group 1 (n = 24; 22.7 ± 3.6 years; 175 ± 4 cm; 77.3 ± 7.6 kg) after ACL reconstruction, Group 2 (n = 21; 20.5 ± 3.7 years; 177 ± 6 cm; 74.3 ± 9.1 kg) with mild lower-limb injuries (grade 1 muscle strains) and Group 3 (n = 20; 23.1 ± 2.8 years; 178 ± 6 cm; 75.8 ± 8.8 kg) without injuries in the past 3 years. The concentric isokinetic test (10 knee flexions and extensions at 60, 180 and 300°/s with a 30 s interval for rest) was performed on both limbs. Fatigue symmetry between the medial and lateral hamstrings was measured with sEMG during 60 s of isometric contractions. In comparison to the other groups, the injured leg demonstrated significantly lower values of peak torque for the quadriceps (G1-G2 = 48%, 38%, 14%; G1-G3 = 49%, 25%, 14%) and hamstring muscles (G1-G2 = 36%, 35%, 18%; G1-G3 = 64%, 28%, 17%) as well as lower values of hamstring muscle work (G1-G2 = 262 J, 157 J; G1-G3 = 219 J, 179 J) and power (G1-G2 = 34 W; 11 W; G1-G3 = 29 W, 12 W). No significant differences were noted in strength between Groups 2 and 3. The significantly higher fatigue of the BF compared to the SEM muscle was seen in Group 1 for the involved (mean difference = 0.12) and uninvolved limbs (mean difference = -0.10), but in Group 2, a non-significant trend towards asymmetry was also noted. No asymmetry in hamstring muscle fatigue was determined in Group 3. The results of our study allow us to indicate that active football players who previously met the RTS criteria, had deficits in lower-limb muscle performance 2-3 years after reconstruction, which could lead to ACL re-injury. This observation is potentially of importance because these deficits may not be subjectively reported by such athletes and also may not be visible in regular orthopedic and physiotherapeutic assessment.



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