Elite Soccer Research Articles

The Role of Macronutrients in the Nutrition of Elite Soccer Players: A Systematic Review

The Role of Macronutrients in the Nutrition of Elite Soccer Players: A Systematic Review

Match performance of elite soccer players in ratio to contextual variables and game structure in the attack and defense phases using InStat Kinematic System. A longitudinal study

The practical value of using the wearable devices for monitoring running performance and contextual variables is that well-chosen performance indicators can help coaches identify good and bad performances of individuals or teams. The aim of the article was to investigate running trends in the ratio to the structure of the game in the offensive and defensive phases of professional soccer players on home and away pitches in Montenegro in three competitive matches of different seasons. The research included 82 professional soccer players. The first sub-sample included 44 professional soccer players, height 185.89 ± 6.29 cm, mass 81.06 ± 5.47 kg, BMI 23.47 ± 0.96 kg/m2, age 28.86 ± 3.85 years. The second sub-sample includes 38 professional football players, height 181.88 ± 6.35 cm, mass 77.28 ± 6.78 kg, BMI 23.32 ± 1.08 kg/m2, age 29.43 ± 5.68 years old. The InStat kinematic system recorded field players using six cameras placed around the perimeter of the field at a minimum height of 12 m, 25 frames per second. Our study indicated some contrasting findings. Statistically significant differences were obtained in all three years in running performance and contextual variables. Our results indicate a decreasing trend in high speed runs distance both in the attack phase and in the defense phase for both teams. The conclusion of this study provided information on performance in soccer, which could consequently improve the applicability of running performance in training and competitions Keywords: performance analysis, match location, sprint, run distance, kinematic monitoring.

The relationships between relative age effect, personality constructs and achievement level in soccer.

Youth soccer academies are challenged with the constant recruitment process of young talented players to select those who will achieve long-term success as an athlete. Youth soccer academies strive to enhance the physical and technical skill development as well as personality development of talented players because psychological characteristics play a crucial role in players' future success in their transition to professional soccer. The least mature players and relatively young players may have a greater need to possess superior technical/tactical or psycho-behavioral skills than those relatively older counterparts because of the higher selection rates of early maturing players. Due to RAEs, a significant decrease in the overall quality of professional soccer teams might be observed because of the loss of talent of physically smaller, but psychologically stronger and more versatile relatively young players who possess proper technical and tactical attributes at an early age. The first objective of this study was to examine any possible relationship between RAE and personality constructs. A second objective was to identify factors and effects that can help in the further improvement of talent selection and equal opportunities for elite youth soccer players based on their underlying RAE. The third objective was to consider the impact of RAE on long-term career development. In this retrospective observational study, 151 elite youth soccer players between 15 and 18 years of age were first grouped in birth quartiles. Personality constructs were then assessed, using a combination of observations, interviews, and a self-assessment questionnaire. Next competition level after 8 years was evaluated to identify RAEs, differences in personality characteristics and opportunities to reach professional soccer player status between relatively older vs. younger players. A clear significant RAE was observed for the whole database (Q1 = 38.4% vs. Q4 = 13.9%) with OR of 2.61 (χ2 = 19.46, p < 0.01, r = -0.85). Relatively young players had higher median scores on personality constructs such as self-confidence (p = 0.04), while relatively old players had higher median scores on personality constructs such as team orientation (p = 0.03). In the long term, more players of the youngest birth quartile were signed as professional players (76.2%), compared with relatively old players (46.6%). 65.0% of the 20 players had the highest total score on personality constructs developed as a professional soccer player, vs. 35.0% of the 20 players with the lowest scores. In conclusion, this study showed not only further evidence of the RAE but also provided evidence supporting "the underdog hypothesis" in national elite youth teams. Relatively young players were also more likely to get higher value senior professional contracts in the long term. We propose that this may be due to the relatively young players developing superior psychological skills and technical expertise to compensate for their early physical disadvantage. This in turn suggests the need for greater awareness of the importance of personality constructs in the future development of youth elite soccer players. Therefore, the crux of the issue is how youth soccer academies elicit the "best of both worlds" ie. moderating RAE whilst also gaining the benefits of the underdog hypothesis by creating the right environment for every player to develop to their full potential in elite youth soccer academies.

Reference values for body composition and physical fitness of young Brazilian elite soccer players.

Objective: a) to verify whether body composition and physical fitness should be analyzed by chronological age and/or maturity stage in young Brazilian soccer players and b) to propose reference values for the evaluation of body composition and physical fitness by maturity stage in elite soccer players. Methods: A descriptive-correlational study was carried out in 206 young Brazilian soccer players (11-16years old). The sample selection was non-probabilistic by convenience. Weight and standing height were evaluated. Body composition (BC) was assessed by dual X-ray absorptiometry (DXA). BC indicators [(percent fat (%F), Fat-free mass (FFM), Fat mass (FM) and Bone mass (BM)] were extracted. For physical fitness (PF), we applied the Flexibility (cm) sit and reach tests, explosive strength tests [Counter Movement Jump CMJ (cm) and horizontal jump HJ (cm)], speed [Speed 10, 20, 30 and 40m (seconds)] and Yo-Yo endurance level I test. Percentiles were constructed for BC and PF using the LMS method [L (Lambda; skewness), M (Mu; median) and S (Sigma; coefficient of variation)]. Results: The explanatory power between chronological age (CA) with BC was: FM (R2 = 0.03%), FFM (R 2 = 0.66%) and BM (R 2 = 0.62%), while between maturity status (MS) with BC were: FM (R 2 = 0.04%), FFM (R 2 = 0.71%) and BM (R 2 = 0.66). The explanatory power between the CA with the physical fitness tests ranged from: (R 2 = 0.22-0.62%). While between MS with physical fitness the values ranged from: (R 2 = 0.23-0.64%). Percentiles per MS (P3, P5, P10, P15, P25, P50, P75, P85, P90, P95 and P97) were proposed for both BC and PF. Conclusion: The results of the study have shown that the evaluation of BC and PF of young soccer players should be performed by controlling for MS rather than for CA. The inclusion of a non-invasive method to control MS by means of percentiles during puberty may contribute to the development of retention and exclusion of young soccer players, thus, they may have a better chance of achieving sporting success.

Jump and sprint force velocity profile of young soccer players differ according to playing position

ABSTRACT Our study aimed to compare explosive performance and underlying mechanical determinants explored through F-V profiles in jumping and sprinting among young soccer players based on their playing position. Ninety elite soccer players were categorized into the following positions: goalkeepers, central defenders, wide defenders, central midfielders, wide midfielders, and forwards. Two testing sessions were conducted to measure the 30-metre sprint time (T30) using an over-ground sprint test and jump height (Hmax) through the SJ test. Results demonstrated performance variations among positions. In sprinting, forwards showed greater T30 (4.5 ± 0.14 s) compared to other positions, with goalkeepers exhibiting the lowest T30 (4.86 ± 0.18 s). Forwards also displayed higher maximal theoretical velocity (8.8 ± 0.4 m.s−1) and power output (Pmax) (19.4 ± 2.6 W.kg−1) than other positions, while goalkeepers had the lowest Pmax (16.5 ± 2 W.kg−1). In jumping, forwards (33.2 ± 3.9 cm) and wide-midfielders (33.6 ± 3.8 cm) achieved higher Hmax compared to goalkeepers (29.2 ± 5 cm) and central-midfielders (29.2 ± 3.8 cm). Wide-midfielders (28.5 ± 4.8 W.kg−1) and forwards (27.1 ± 4.3 W.kg−1) surpassed goalkeepers (23 ± 2.8 W.kg−1) and central-midfielders (25.1 ± 3.8 W.kg−1) in Pmax. Our findings reveal substantial position-related disparities in F-V profiles among elite young soccer players, in sprinting and jumping emphasizing the need for position-specific training programmes to optimize player development and on-field performance from an early age.

Artificial Turf Increases the Physical Demand of Soccer by Heightening Match Running Performance Compared with Natural Grass.

Modric, T, Esco, M, Perkovic, S, Basic, Z, Versic, S, Morgans, R, and Sekulic, D. Artificial turf increases the physical demand of soccer by heightening match running performance compared with natural grass. J Strength Cond Res 37(11): 2222-2228, 2023-This study aimed to determine differences in match running performance (MRP) of elite soccer players (n = 31) during matches played on artificial turf (AT) and natural grass (NG). The players' MRP (AT; 131 observations, NG; 135 observations) were collected during official matches (n = 32) using global positioning system and classified according to their playing positions as central defenders, central midfielders, fullbacks, forwards, and wingers. The MRP variables included total distance covered (TD), low-intensity running (LIR), moderate-intensity running (MIR), high-intensity running (HIR), total (Tacc) and high-intensity accelerations (Hacc), and total (Tdec) and high-intensity decelerations (Hdec). The influence of match outcome, location, and opponent quality was controlled for as contextual factors. Playing matches on AT resulted in (a) increased TD (Cohen's d (d) = 0.55, 0.61, and 0.28, respectively), MIR (d = 0.91, 0.79, and 0.49, respectively), and HIR (d = 0.67, 0.44, and 0.38, respectively) for central defenders, central midfielders, fullbacks; (b) increased Tacc (d = 0.38, 0.37, and 0.4, respectively) and Tdec (d = 0.31, 0.34, and 0.31, respectively) for central defenders, central midfielders, and wingers; and (c) decreased Hdec (d = -1.5) for forwards. These results show that playing on AT is more physically demanding for defensive and midfield players than playing on NG. Soccer coaches should consider implementing preparatory strategies that mitigate the increased demands of playing on AT for these players, especially before a competitive period when transitions between pitch surfaces routinely occur.

The Influence of Somatic Maturity on Anthropometrics and Body Composition in Youth Soccer Players.

The primary aim of this investigation was to compare players' anthropometric (AP) and body composition (BC) characteristics between distinct maturity bands (pre-PHV, circa-PHV, post-PHV) in youth elite soccer. This study considered 320 male soccer players (mean age 13.8 y). Participants were from U14 (n = 157) and U15 (n = 163) age categories. The Khamis-Roche method was applied to calculate the percentage of predicted adult height (PAH) at the time of assessment based on which the players were further divided into maturity bands (pre-PHV ≤ 87%, circa-PHV = 88-95%, post-PHV > 95%). The findings indicated that most of the players were in the circa-PHV stage at the time of investigation. Measurements included height and weight. The estimates of BC parameters were derived using bioelectrical impedance (BIA) analysis. These various AP and BC attributes displayed significant differences among the maturity bands (F = 139.344-7.925; p < 0.001; large effect sizes) except in body fat mass (BFM) (F = 2.998; p = 0.051; small effect size). The current somatic maturity stage of the athletes should be considered when evaluating BC results, otherwise there is a risk of misinterpretation.

Effects of the New COVID-19-Induced Rule on Substitutions and Performance in Italian Elite Soccer.

COVID-19 has resulted in widespread changes, including within the realm of sports. Professional soccer has adapted by allowing more substitutions, leading to tactical adjustments and potential physical benefits. Accordingly, this study analyzed the impact of the new rule in Italian top-level soccer, focusing on substitution patterns and performance differences between the pre-COVID (2017-2018, 2018-2019 seasons) and post COVID (2020-2021, 2021-2022 seasons) eras. As such, publicly available data from 1520 matches (760 matches per era) were recorded. The sample included matches played from 40 Italian top division teams in both the pre- and post-COVID eras. Analyses confirmed substitutions follow a consistent temporal pattern throughout the match in both eras, highlighting a slight difference in second-half management, and showed the new rule is still not used to its full potential, thus raising concerns about teams' financial strength, as not all managers possess "deep benches" (i.e., a large number of top-level players available to play). Further analyses revealed a statistically significant increment (p = 0.002) in the quantity of collectively produced sprints in the post-COVID era compared to the pre-COVID one. The results from this study emphasize the need to carefully address sprint preparation and repeated sprint abilities, also considering factors such as the number of substitutes and their skill level.

Exploring the interplay between metabolic power and equivalent distance in training games and official matches in soccer: a machine learning approach.

Introduction: This study aimed to explore the interplay between metabolic power (MP) and equivalent distance (ED) and their respective roles in training games (TGs) and official soccer matches. Furthermore, the secondary objective was to investigate the connection between external training load (ETL), determined by the interplay of metabolic power and equivalent distance, and internal training load (ITL) assessed through HR-based methods, serving as a measure of criterion validity. Methods: Twenty-one elite professional male soccer players participated in the study. Players were monitored during 11months of full training and overall official matches. The study used a dataset of 4269 training games and 380 official matches split into training and test sets. In terms of machine learning methods, the study applied several techniques, including K-Nearest Neighbors, Decision Tree, Random Forest, and Support-Vector Machine classifiers. The dataset was divided into two subsets: a training set used for model training and a test set used for evaluation. Results: Based on metabolic power and equivalent distance, the study successfully employed four machine learning methods to accurately distinguish between the two types of soccer activities: TGs and official matches. The area under the curve (AUC) values ranged from 0.90 to 0.96, demonstrating high discriminatory power, with accuracy levels ranging from 0.89 to 0.98. Furthermore, the significant correlations observed between Edwards' training load (TL) and TL calculated from metabolic power metrics confirm the validity of these variables in assessing external training load in soccer. The correlation coefficients (r values) ranged from 0.59 to 0.87, all reaching statistical significance at p < 0.001. Discussion: These results underscore the critical importance of investigating the interaction between metabolic power and equivalent distance in soccer. While the overall intensity may appear similar between TGs and official matches, it is evident that underlying factors contributing to this intensity differ significantly. This highlights the necessity for more comprehensive analyses of the specific elements influencing physical effort during these activities. By addressing this fundamental aspect, this study contributes valuable insights to the field of sports science, aiding in the development of tailored training programs and strategies that can optimize player performance and reduce the risk of injuries in elite soccer.

Refeeding Days Strategies Applied in Elite Soccer Player Week Dietary Intake: A Short Communication

Even knowing that elite soccer players body fat mass does not undergo major changes and remains stable and similar across all age groups they ever want to reduce their body fat percentage because, according to their own reports, by doing this they felt light on the pitch. However, during the off-season soccer periods, the elite soccer players tends reduced you performance after training and matches cessation [1], something that could put into question the need for a diet rich in carbohydrates on this moment due increasing body fat percentage fear. However, there is a strategy for prescribing hypocaloric diets commonly used by resistance athletes during reduce body fat percentage phases, which is called refeeding days. Basically, the strategy consists of a calorie-restricted diet during the week and two days during weekends with 100% energy requirements, something that correlates performance maintenance at body fat percentage reduction [2]. And thinking about, it is something that could correlate with elite soccer players reducing caloric intake and training level during soccer off-seasons with diet strategies that can help them maintained sports performance and low body fat percentage during this phase. A study can prove scientifically that hypocaloric diets on low carbohydrate consumption during short periods were able to decrease body fat in elite soccer players without to harm their performance [3]. Thus, it becomes necessary to understand some methodology that leads the athlete to a low-carbohydrate diet, does not make him lose performance over time and maintains his body composition as desired by him. Thus, knowing that the refeeding days strategies can be used implementing one or two days at high carbohydrate and energy intake (generally at or slightly above body weight maintenance levels), thereby providing a break on the another five consecutive days of low carbohydrate and hypocaloric diet [4], this diet model would add as one more strategy to be recommended for soccer players who try to lower the body fat percentage without worse the performance, becomes this proposal for these athletes interesting. Furthermore, dietary prescriptions for athletes who want to reduce body fat percentage remain within the range of less than 45 kcal/kg-1 lean body mass/day-1, carbohydrates between 3 and 5 g/kg-1 body weight/day-1, proteins between 1 and 3 g/kg-1 body weight/day-1 and the dietary fat prescription percentage comprising 20 to 30% of the total energy value of the diet [5-7]. And for athletes who need to optimize performance, the carbohydrate recommendation is within the range of 5 to 10 g/kg-1 body weight/day-1 and in this case the protein can reach the highest range of the recommendation and go up to 4 g/kg-1 body weight/day-1 [8,9]. This way, a strategy refeeding days model was proposed by the author in Table 1, as a strategy that can be used to decrease the body fat percentage of the elite soccer player with the possibility of not harming his performance.

Association between sports expertise and visual attention in male and female soccer players.

Visual attention plays a crucial role in daily living and in sports, affecting an athlete's performance and thus, potentially, the outcome of a match. However, studies assessing the association between the level of sports expertise and visual attention have yielded mixed results. This study was conducted to examine whether visual attention could be developed with increased sports expertise, and whether visual attention differed between male athletes and female athletes. A total of 128 participants were included in this study: 64 first-level national soccer athletes recruited from college soccer teams (considered elite athletes; 32 men and 32 women with similar soccer performance requirements and training experience), and 64 physical education college students with limited soccer experience (considered novice athletes; 32 men and 32 women with matched soccer experience). To assess visual attention, we used a multiple object tracking (MOT) task with four targets among a total of 10 objects moving at a fixed speed of 10°/s in random directions across a computer monitor screen. Tracking accuracy on the MOT task was calculated for each participant as the proportion of correctly selected targets. A univariate analysis of variance was performed, with group (expert, novice) and sex (male, female) as independent variables, and tracking accuracy on the MOT task as the dependent variable to assess whether sports expertise or sex influenced visual attention. Simple effects tests followed by comparisons with Bonferroni corrections were used, and effect size calculations were performed using Cohen's f statistic. Tracking accuracy on the MOT task was significantly affected by sports expertise (F(1,124) = 91.732, p < 0.001, ηP2 = 0.425), with accuracy among expert soccer athletes superior to that among novice soccer athletes. Moreover, a statistically significant interaction between sports expertise and sex was detected (F(1,124) = 7.046, p = 0.009, η P2= 0.054). Better tracking performance was observed for male soccer players (mean [SD], 0.39 [0.12]) than for female soccer players (mean [SD], 0.27 [0.08]); p<0.01; d=1.17; r=0.51) but only in the novice group. No significant sex difference was detected in tracking performance between elite male soccer athletes (mean [SD], 0.51 [0.09]) and elite female soccer athletes (mean [SD], 0.49 [0.11]). These findings confirm previous results indicating that long-term extensive sports training develops visual attention as assessed by MOT performance and extend previous findings to include soccer athletes. The findings of a sex difference in visual attention among novice soccer players but not among elite soccer athletes who had similar performance requirements and training experience suggest that long-term extensive training may minimize the sex difference in visual attention.

Anthropometric Values in Spanish Elite Soccer: Differences between Divisions and Playing Positions

Body composition is an important factor in a soccer player’s performance, and anthropometry is one of the most widely used methods of measurement. The physical demands of Spanish soccer have evolved over time, so the ideal body composition requirements must be adapted to the present day. The aim of this study was to describe the anthropometric and body composition profiles of professional soccer players in the second, second B, and third divisions during the 2019–2020 season in order to compare the anthropometric parameters of players among positions and competitive divisions. A cross-sectional study was conducted to determine differences in kinanthropometric and derived variables in a sample of Spanish soccer players. A total of 615 soccer players from the second (116 players), second B (310 players), and third (189 players) divisions participated in this study. After comparing the groups according to the playing position and category, it was observed that at higher levels of play, soccer players show lower values of fat mass (FM) and higher values of muscle mass (MM) and bone mass (BM); at lower levels of play, soccer players show more anthropometric differences between playing positions. Lastly, the somatotype of the elite soccer player is balanced mesomorphic, with higher levels of mesomorphy at higher levels of play. In summary, this is the first study to evaluate the body composition of the different Spanish soccer divisions.

Return-to-performance in elite soccer players after Achilles tendon ruptures: a study using a weighted plus/minus metric and matched-control analysis

PurposeStudies have shown decreased match participation and shortened careers in athletes suffering Achilles tendon ruptures (ATRs), but assessment using a true performance metric is lacking. Plus/minus (PM) metrics provide a practical and objective approach to player performance assessment and are commonly used in other sports. This study aimed to quantify and compare individual player performance variations in elite football league players who sustained ATRs and returned to play within 1 year compared to those without ATRs, using a PM metric.MethodsPlayer and team data were sourced from Transfermarkt.com. Male players sustaining ATRs between 2007 and 2018 were identified through injury reports. A control group (CTRL) was matched by position, age, height, and league, with a 6:1 ratio of controls to ATR subjects. The day of injury was considered “time zero”. Year -1 corresponds to the 360 days preceding injury, and Year 1 to the interval between 360 and 720 days after. Performance in the player’s main team was evaluated using a previously validated weighted PM metric. Only data from Year -1 and Year 1 were used for ATR versus CTRL group comparisons. Statistical significance was set at p < 0.05.ResultsThe ATR group included 125 athletes. Data from more than 76,000 matches were analyzed. No statistically significant differences in net weighted PM metric between Year -1 and Year 1 were found.ConclusionNo differences were found between athletes suffering from ATRs and controls regarding the weighted PM metric.Level of evidenceIII.

In-situ acceleration-speed profile of an elite soccer academy: A cross-sectional study

ABSTRACT Speed is an essential skill in sports performance and an important performance metric in talent identification. This study aims to evaluate and compare the sprint acceleration characteristics across different age groups in an elite soccer academy. A total of 141 elite academy soccer players were recruited to participate in the study, and they were assigned to their respective competitive age groups, ranging from under-14 to the B-team. An individual in-situ acceleration-speed (A-S) profile was assessed and derived from Global Position System (GPS) speed-acceleration raw data, from 10 consecutive football sessions, in the beginning of the season. The results showed that under-14 players exhibited significantly lower theoretical maximum speed (S0) ( η p 2 = 0.215, p < 0.01) when compared with all other age groups. However, no differences were found between maximum theoretical acceleration (A0) and A-S slope between age groups. The results suggest that sprint mechanical profiles of young soccer athletes remain stable throughout their athletic development. Nevertheless, younger athletes have less capacity to apply horizontal force at higher speeds (S0).

Injuries in professional women’s elite soccer players in Kosovo: epidemiological injury study

BackgroundAn emphasis has been given lately towards women’s engagement together with their potential in soccer. As this sport develops with athletes becoming more physically fit and skilled, it is unclear what the consequences in terms of injuries are. Having this in mind, this study aimed to investigate the major injuries that occur in women’s soccer players.MethodsThis descriptive epidemiological study invited all 286 women’s soccer players from the 12 participating women clubs in the Kosovo 1st Soccer League (elite football level) during the 2021/2022 season, out of which 142 from 12 clubs participated. Exposure time for 1000 h of playing and training were recorded in addition to the anthropometric data, playing position, and prior injury history during the end of the season, practice, and match. The exact type of injury, severity, and post-injury recovery time, as well as the circumstances surrounding the injuries, were recorded.ResultsIn total 84 injuries were registered with an overall injury ratio (IR) being 3.21 (CI: 2.56, 3.98) injuries/1000 exposure hours. During the competitive season, each player sustained 1.4 injuries on average. IRs were significantly higher during competition (n = 50; IR = 1.57; CI: 1.52, 1.62) compared to training (n = 34; IR = 0.26, CI: 0.25, 0.27). Out of a total of 142 women players, 84 (59.2%) injuries occurred, and no record of injuries was made in 58 (40.8%) players. The overall IR was observed to be 3.21 (CI: 1.24, 3.27), with moderate and severe injuries accounting for 38.1% of total injuries (each), followed by mild (16.7%) and minimal (7.1%) injuries.ConclusionThe women IR in Kosovo women’s soccer players is low while being circa 11% below the international average. Almost 2 out of every 4 injuries were categorized as traumatic, with the IRs being more than 5-fold larger during games than during training. Additionally, these findings emphasize the higher rate of injuries amongst younger athletes, suggesting caution to be taken by the coaches when planning for the match. The collected data may help coaches and trainers create more targeted women’s soccer injury prevention programs.

Sleep disorders and their relation to injuries among young elite soccer players

Aim: to study the quality of sleep and the relationship between sleep disorders and injury among young elite soccer players.Methods: the study summarizes data from relevant questionnaires obtained through anonymous cohort testing of 236 male football players from leading football academies, two farm teams of leading Russian Premier League clubs and three national youth teams.Results: the average sleep duration in the study participants was 9 hours. The prevalence of sleep disorders was 7 % (PSQI, Pittsburgh Sleep Quality Index) and 10 % (ASBQ, Athlete Sleep Behavior Questionnaire) and among the youngest soccer players, this prevalence of violations was the lowest. Significant or moderate daytime sleepiness was found in 59 % of participants. The risk of serious disorders increased with age. Sleep disorders significantly affected injuries according to the results of the PSQI questionnaire and retrospective collection of information about injuries.Conclusion: the confirmed relationship between injuries and sleep disorders allows us to consider sleep quality improvement as an important component of injury and morbidity prevention among athletes of team sports.

The prevalence of alcohol and pre-workout caffeine consumption and their effect on injuries and sleep disorders in young elite soccer players

Aim: to study the prevalence of alcohol and pre-workout caffeine use and their impact on sleep quality and injury among the young soccer players.Methods: this study examined the prevalence of alcoholic beverages and pre-workout caffeine consumption in young soccer players, as well as the effect of these substances on sleep disorders and injuries among 236 elite athletes aged 11–21 years.Results: 16.5 % of soccer players use pre-workout caffeine. Most often 1–2 times per week. Caffeine consumption is weakly positively correlated with age (p &lt; 0,001, R = 0,41.) and is most common in the age group of 19–21 years with consumption rates at 58.8 %. 17.3 % of young soccer players consume alcohol moderately and its consumption significantly correlates with age. Most often alcohol was consumed at the age of 19–21 years. Alcohol and caffeine consumption are significantly, but weakly correlated with the risk of severe sleep disorders on the Athlete Sleep Behavior Questionnaire (ASBQ). However, injuries during matches and training sessions did not depend on alcohol (p = 0.076) or caffeine (p = 0.14) consumption according to the Kraskal — Wallis test. At the same time, sleep disorders on the ASBQ significantly correlated with injury.Conclusion: the widespread use of alcohol and caffeine, and their negative impact on sleep among soccer players aged 11–21 years were revealed, but there was no connection between the use of these substances and injuries.

Dietary Habits of Elite Soccer Players: Variations According to Competitive Level, Playing Position and Sex.

Soccer is a sport practiced worldwide by both men and women, where nutrition plays a fundamental role in the performance of soccer players, providing them with the nutrients necessary for energy, muscle recovery and injury prevention. The aim of this study is to describe the dietary habits in elite soccer players and their association with their competitive level, playing position and sex. A descriptive and non-experimental comparative study was conducted during the 2021-2022 competitive season. A total of 105 players belonging to a Spanish elite soccer team completed a food frequency questionnaire (FCFQ). It was observed that male players presented a higher consumption of carbohydrate-rich foods (p < 0.05), fermented foods (p = 0.014), frozen foods (p = 0.049) and red meat (p = 0.012) compared to female players, with the exception of lean meats, which were higher in females (p = 0.012). Furthermore, the U16-15 categories stand out for consuming carbohydrate-rich foods such as pasta (p = 0.000), bread (p = 0.004) and sweets (p = 0.046), as well as frozen foods (p = 0.002). Finally, alcohol consumption is higher in the senior categories (42.9%), where men are more likely to drink mixed drinks (6.2%), and beer and wine by women (10.7%). Practically no differences were found between the playing positions. In conclusion, differences were found in FCFQ according to competitive level and sex.

Normative reference and cut-offs values of maximal aerobic speed-20 m shuttle run test and maximal oxygen uptake for Tunisian adolescent (elite) soccer players

This study aimed to develop reference curves of aerobic parameters of 20 m shuttle run test for Tunisian soccer players. The study was conducted in the 2022/2023 pre-season. The reference curves of the maximal aerobic speed (MAS) and the maximal oxygen uptake (VO2max) were developed according to the Lambda, Mu and Sigma (LMS) method, using data from 742 Tunisian premier league soccer players aged 11–18 years. Measured variables included: weight, height, body mass index and maximal heart rate (HRmax). HRmax was measured when the participants completed the maximal aerobic speed. VO2max was estimated using the 20 m shuttle run test protocol (speed increment every minute). Our results presented the smoothed percentiles (3rd, 10th, 25th, 50th, 75th, 90th and 97th) of MAS (km/h) and VO2max (ml/kg•min⁻1) according to age. In addition, raw data showed that VO2 max was positively correlated with age (r = 0.333; P < 0.001), height (cm) (r = 0.279; P < 0.001), weight (kg) (r = 0.266; P < 0.001), practice period (years) (r = 0.324; P < 0.001) and BMI (kg/m2) (r = 0.10; P < 0.05). However, it was negatively correlated to HRmax (bpm) (r = −0.247; P < 0.001). Only the measurements within the age group [12–12.99] are significantly higher (p < 0.001; ES = 0.63) compared with the previous age group [11–11.99]. Finally, regarding prevalence, our findings showed that 15.5 % of the players in our sample had VO2max values above the 87.7th percentile cut-off, while only 0.3 % exceeded the 99.18th percentile. The development of normative curves could help coaches and physical trainers to more accurately detect weaknesses in the aerobic performance of their players in order to sustain high-intensity repetitive actions during a soccer match.

Effects of Training Using Self-Modeling with Visual Cues on Skill Performance, Imagery, and Sports Confidence of Adolescent Female Soccer Players

PURPOSE This study aimed to examine the effects of motion analysis and image training using self-modeling with visual cues on the skill performance, imagery, and sports confidence of adolescent female soccer players.METHODS The participants were elite soccer players from two girls’ high school soccer teams divided into an experimental group (D girls’ high school, n=16) and a control group (I girls’ high school, n=13). The experimental group underwent motion analysis and image training when performing penalty kicks, short kicks, and long kicks using selfmodeling with visual cues, while the control group underwent training using selfmodeling videos without visual cues. Before and after the training, the evaluation score was calculated according to kick performance, and the imagery and sports confidence factors were measured. For the statistical analysis of all collected data, descriptive statistics, the Friedman test, the Mann-Whitney U test, and two-way repeated-measures analysis of variance were used.RESULTS First, on the motion analysis using self-modeling with visual cues, the experimental group’s penalty kick and short kick scores were improved and differed significantly, but no significant change was noted in long kick score. Second, as a result of image training using selfmodeling with visual cues, all visual, kinesthetic, mood, and controllability factors of the experimental group improved except for the auditory factor, and the interaction effect was confirmed. In addition, the stated sports confidence of the experimental group was improved and the interaction effect confirmed.CONCLUSIONS The analysis of kick motion using self-modeling with visual cues was effective for the penalty kicks and short kicks of adolescent female soccer players. Moreover, this study confirmed that the analysis of kick motion improved the visual, kinesthetic, mood, and controllability sub-factors of imagery and significantly affected the players’ stated sports confidence.