Brazilian Soccer Players Research Articles

Potential financial loss and risk factors for hamstring muscle injuries in elite male Brazilian soccer players: a season-long prospective cohort pilot study.

The aim of this pilot study was to analyze the potential financial loss and a range of potential risk factors for hamstring muscle injuries in elite Brazilian soccer. Thirty-four male players (age: 25 ± 6 years; stature: 180 ± 8 cm; body mass: 78 ± 9 kg; minutes played in matches: 2243 ± 1423 min) from an elite professional soccer club were monitored during a 12-month season. Muscle injury was identified by magnetic resonance imaging and the severity was defined according to the number of days away: minimal (1-3 days), mild (4-7 days), moderate (8-28 days), severe (>28 days). Potential financial loss due to the team's under achievements was determined. Dorsiflexion range of motion, eccentric knee flexor strength and isokinetic tests were performed during the pre-season. Association between dependent variables and the occurrence of injury was evaluated. Nine hamstring muscle injuries with moderate severity were found in 8 athletes. Recovery time was 22 days off the field on average. Potential financial loss was $-43.2 million USD and earnings on merit money was 21%. Previous injury, increased flexor deficit 60° /sec and increased flexor fatigue index 300°/sec were all associated with a greater chance of hamstring muscle injury. Ankle dorsiflexion range of motion was significantly lower in the injured group (35.6 ± 3° vs. 39.1 ± 4.9°; p = 0.017, effect size = -0.74). High financial burden was found in elite Brazilian soccer during one full season. Injured athletes had high hamstring fatigue index, knee flexor strength deficit, ankle range of motion restriction and previous hamstring muscle injury when compared to non-injured athletes. Therefore, preventive approaches in professional soccer players with previous hamstring injuries should be a priority.

Influence of ACTN3 R577X Polymorphism on Blood Creatine Kinase Levels Relative to Number of Sprints in Brazilian Professional Soccer Players.

This study sought to assess how post-game creatine kinase (CK) levels correlate with the number of sprints and the impact of the ACTN3 polymorphism on this response. This research constituted a descriptive/observational, retrospective cross-sectional study. DNA was extracted from blood samples for ACTN3 polymorphism genotyping. CK was measured 48 h after official matches, and the number of sprints (>19 km/h) was tracked using Global Positioning System (GPS) technology. The main cohort included 23 professional soccer players from the top tier of the Brazilian Championship. We analyzed 115 GPS + CK data sets. The replication cohort comprised 18 professional soccer players from the First Division of the Championship, had the same methodology applied, and featured a total of 90 GPS (sprints > 25.2 km/h) + CK data sets. For the main cohort, a significant positive correlation was seen between the number of sprints and the CK levels (p = 0.009). Athletes with the ACTN3 RR genotype had higher CK levels as more sprints were performed during the match (p = 0.017). However, the relationship was not found for X allele carriers (p > 0.05). For the replication cohort, there was a near-significant correlation between CK levels and the number of sprints (p = 0.05), and RR individuals showed a significant association (p = 0.01), whereas X allele carriers did not (p = 0.06). A greater number of sprints during matches is linked to higher CK levels, primarily among players with the ACTN3 RR genotype, which is potentially due to an increased presence of type II muscle fibers. These findings were replicated for both cohorts of elite Brazilian soccer players, emphasizing the importance of genetic factors in injury prevention.

Mapping talent pathways: A comparative study of developmental activities and practice structure in Brazilian and Spanish U-18 elite youth male soccer players

The purpose of this study was threefold: (1) to compare the engagement in various types and amounts of soccer activities during childhood and adolescence between Brazilian and Spanish elite youth soccer players; (2) to test what talent development pathway characterizes youth development in elite soccer in Brazil and Spain and (3) to compare the practice structure between elite youth soccer in Brazil and Spain. Participants were 131 U-18 elite male soccer players from Brazil ( n = 68) and Spain ( n = 63) competing in the national league. The Participant History Questionnaire was used to measure the soccer activities undertaken by players. Developmental activities were analyzed for two age periods: childhood (6–12 y/o) and early adolescence (13–15 y/o). In Spain, players started their involvement in practice and competition in soccer earlier compared to Brazilian players ( p < .05). Brazilian players were more involved in structured activities, such as practice in soccer and futsal, and participated in a greater number of sports in childhood and early adolescence ( p < .05). We found a very similar percentual practice structure (individual, pair, drills, group tactics and collective tactics activities) between Spain and Brazil, although Brazilian players accumulated a greater practice volume. It is concluded that Spanish and Brazilian U-18 elite youth male soccer players were differentiated by their milestones in soccer and their engagement in practice activities during childhood and early adolescence. Talent development pathway of male soccer players in Spain was characterized by the early engagement pathway, while the Brazilian system was characterized by the specialized sampling model.

Effects of Contextual Variables on Match Load in a Professional Soccer Team Attending to the Different Season Periods.

This study aimed to analyze the effects of contextual variables (i.e., match location and match outcome) and season periods on match load (i.e., internal and external load) in professional Brazilian soccer players. Thirty-six professional players from the same soccer team participated in this study. The season was split into four phases: matches 1-16 (i.e., Phase 1 = P1); matches 17-32 (i.e., Phase 2 = P2); matches 33-48, (i.e., Phase 3 = P3); matches 49-65 (i.e., Phase 4 = P4). Considering match outcome, when the team wins, Cognitive load, Emotional load, and Affective load were significantly higher in away vs. home matches (p < 0.05). Considering season phases, in P3, Mental Fatigue was significantly higher in drawing than in losing matches (p < 0.05). Additionally, considering the match outcome, when the team lost, Total Distance (TD)/min and TD > 19 km·h-1/min were significantly lower in P1 than P2 (p < 0.001), P3 (p < 0.001), and P4 (p < 0.001). These results suggest to strength and conditioning coaches the need to consider the outcome and location of the previous game when planning the week, as well as the phase of the season they are in to reduce fatigue and injury risk.

VALOR DE CORTE PARA CLASSIFICAÇÃO DA ASSIMETRIA DE FORÇA EM JOGADORES DE FUTEBOL

Introduction: Strength asymmetry in soccer players may arise from unilateral demands along years of training and may be related to higher injury risk and performance impairment. However, cut-off values used to classify asymmetry can be different among tests or outcomes. Objective: The aim was to compare the distribution of soccer players classified as symmetric or asymmetric based on the arbitrary cut-off value of 15% and the Upper Limit Value method for impulse and peak force. Methods: 184 professional Brazilian soccer players did the countermovement jump test on two force plates. The symmetry index was used to quantify the asymmetry of peak force and impulse. Then, cut-off value of 15% was compared with the cut-off value estimated from the Upper Limit Value. McNemar χ² test was used to verify the concordance of diagnostic. Results: Upper Limit Value for peak force and impulse asymmetries were 10.86% and 25.31%, respectively. McNemar χ² test confirmed the hypothesis, that the classification of athletes would be statistically different between cut-off values. Conclusions: We concluded that cut-off values based on Upper Limit Value for impulse and peak force were different from the 15% cut-off values. Coaches should be aware of this different classification choosing the cut-off value that best fits their team. Level of Evidence II; Diagnostic Studies–Investigation of a Diagnostic Test.

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.

Replicative Study in Performance-Related Genes of Brazilian Elite Soccer Players Highlights Genetic Differences from African Ancestry and Similarities between Professional and U20 Youth Athletes.

Classically, genetic association studies have attempted to assess genetic polymorphisms related to human physiology and physical performance. However, the heterogeneity of some findings drives the research to replicate, validate, and confirmation as essential aspects for ensuring their applicability in sports sciences. Genetic distance matrix and molecular variance analyses may offer an alternative approach to comparing athletes' genomes with those from public databases. Thus, we performed a complete sequencing of 44 genomes from male Brazilian first-division soccer players under 20 years of age (U20_BFDSC). The performance-related SNP genotypes were obtained from players and from the "1000 Genomes" database (European, African, American, East Asian, and South Asian). Surprisingly, U20_BFDSC performance-related genotypes had significantly larger FST levels (p < 0.00001) than African populations, although studies using ancestry markers have shown an important similarity between Brazilian and African populations (12-24%). U20_BFDSC were genetically similar to professional athletes, showing the intense genetic selection pressure likely to occur before this maturation stage. Our study highlighted that performance-related genes might undergo selective pressure due to physical performance and environmental, cognitive, and sociocultural factors. This replicative study suggests that molecular variance and Wright's statistics can yield novel conclusions in exercise science.

The relationship between deliberate practice, play, and futsal in childhood and adolescence and the development of different decision-making skills in professional female soccer players

Soccer players’ ability to make efficient and quick decisions has gained more importance due to the increase in game speed in the last few years. Therefore, this study aimed to examine the relationship between the engagement in previous developmental activities in soccer and futsal with the quality and speed of decision-making skills in different phases of sport development of elite female soccer players. The sample comprised 77 elite Brazilian professional female soccer players. Players’ decision-making skills were assessed based on an objective video-based test – TacticUP®. We used a retrospective questionnaire to collect information about previous participation in different developmental activities. The results showed that engagement in deliberate practice in soccer and futsal, especially during childhood and early adolescence, is related to a better quality of offensive decision-making skills, although showing small to medium effect sizes. We highlight that deliberate practice in futsal is associated only with offensive decision-making skills with the ball and near the ball. In turn, engaging in deliberate play in soccer, mainly in childhood and early adolescence, is related to quicker offensive and defensive decision-making skills, showing mostly medium effect sizes. To the best of our knowledge, it was the first study to measure the relationship of decision-making speed with developmental activities in soccer. It is concluded that deliberate practice in soccer and deliberate play in soccer are associated with different dimensions of decision-making skills.

Comparison between nonperiodized resistance training and nonlinear periodization on muscular peak power in Brazilian soccer players

Background: For decades the literature has been investigating the ideal dose-response regarding the frequency, intensity and volume of training that optimize the increase in muscle strength and power in athletes and non-athletes. Objective: Evaluate the effects of strength training from a nonlinear (NLP) and non-periodized (NP) model on muscular peak power in soccer players. Methods: Twelve male junior football players from a professional team in Cabo Frio (Brazil) were recruited and randomly divided into two groups (6 in each group). The groups were randomly divided into: G1 - (Body mass: 64.7 ± 6.5 kg; Height: 172.3 ± 5.8 cm; % fat: 5.1 ± 2.7; Age: 17.5 ± 1.0 years) performed RT with NLP model; G2 - (Body mass: 66.1 ± 4.7; Height: 177.1 ± 6.1 cm; % fat: 5.1 ± 1.2, age: 17.6 ± 0.5 years) performed RT with NP model. Both groups are subjected to 12 weeks of training. PNL strength training consisted of weight training sessions on alternate days, 3 times a week, the rest intervals were 120s among the exercises and included 10 exercises. NLP distribution was as follows: Day 1 (3x4-6 maximum repetitions [RM] with rest intervals of 120 sec between sets); Day 2 (3x8-10RM with 60-90 rest intervals between sets); and day 3 (3x12-15RM with rest intervals of 60 sec between sets). NP training performed the same duration, weekly frequency, exercises and number of sets (3 sets 8-10RM and 60-90 sec rest intervals). Before and after NP and NLP training, muscle peak, speed and agility were evaluated. Results: The ANOVA with mixed model showed no significant interaction between group and moment (F(1,10) = 0.133; p=0.72), and no significant main effect for group (F(1,10) = 0.032; p=0.86) in muscular peak power. There was a significant main effect for moment (F(1,10) = 14.872; p=0.003), where were showed that Post-training presented higher values of muscular peak power compared to Baseline (p= 0.003). Conclusion: It is concluded that both training organization models are effective and can be used to develop peak muscle power.

Selected soccer players are quicker and better decision-makers in elite Brazilian youth academies

ABSTRACT Studies in talent identification and selection showed that more talented players usually possessed better decision-making skills. Nevertheless, studies on this topic have not yet been carried out: 1) assessing both decision-making time and quality based on offensive and defensive skills among selected and deselected youth soccer players; 2) neither assessed South American samples. This study aimed to compare the decision-making skills among selected and deselected players from Brazilian elite youth soccer academies. The sample comprised 317 Brazilian youth elite male soccer players (U-14, U-15, U-16, and U-17) from teams of the first national division in Brazil. Players’ decision-making skills, both quality and response time, were assessed with an objective video-based test (TacticUP®). Results showed that selected players, compared to those deselected, possessed advantages (p < 0.05) in every age group assessed on: 1) the decision-making time (U-16 and U-17); 2) the quality of decision-making (U-15); or 3) in both decision-making quality and time (U-14). Moreover, among all variables assessed (n = 72), the deselected players did not show any advantage compared to the selected ones. It is concluded that selected players by youth elite soccer academies in Brazil possess superior decision-making skills related to decision time and quality compared to those deselected.

Association between internal training load and muscle injuries in Brazilian professional soccer players.

The training load is associated with injury risk in a variety of sports. This study aimed to evaluate the association between the internal training load and injury risk in Brazilian professional soccer players. The data were collected from 32 soccer players across two full seasons (2017 and 2018). The rating of perceived exertion (RPE) for every training/match session was used as an internal load variable. The cumulative training load from 3 and 4 weeks (C3 and C4) and the acute:chronic workload ratio (ACWR) were calculated. A generalized estimating equation analysis was applied to examine associations of non-contact muscle injuries with C3, C4 and ACWR. A total of 33 injuries were recorded across the two full seasons. A significant association was found between cumulative training load for three (C3, p = 0.003) and four weeks (C4, p = 0.023) and the occurrence of injuries. Players in the "high load" group presented greater injury risk in relation to the "moderate load" group (C4: OR = 4.5; IC 95% 1.5-13.3; C3: OR = 3.7; IC 95% 1.7-8.1). There was no association between ACWR and injury occurrence. The athletes exposed to a high cumulative load in a period of 3 to 4 weeks presented higher injury risk in comparison to those who had moderate cumulative training loads. Besides that, there was no association between ACWR and injury occurrence.

Do contextual variables influence the spatial organisations of elite-level Brazilian professional soccer players?

Purpose.This study investigated the influence of contextual variables on individual and collective team spatial organisation in professional Brazilian players.Methods.Seventeen matches were analysed during the 1st division Brazilian National football League of 2019. Global Positioning System devices were used to track players’ in-game movements. The data were analysed using Matlab to calculate linear tactical variables. The selected tactical variables were ‘Distance from the last defender to the goal’; ‘Width and length’; ‘LpWratio’; ‘Spread’; ‘Space exploration index’ and ‘Stretch index’. Five contextual variables were considered: (i) playing time, (ii) match location, (ii) ranking of the opposition, (iii) match outcome, and (iv) match status.Results.Results demonstrated that the LpWratio values were significantly greater during the second half of matches when compared with the first half (&lt;i&gt;p&lt;/i&gt; = 0.03; &lt;i&gt;d&lt;/i&gt; = 0.62). Significantly greater length and spread values were identified when the team was playing against a bottom six team when compared with the medium eight teams (&lt;i&gt;p&lt;/i&gt; = 0.05; &lt;i&gt;d&lt;/i&gt; = 1.58–1.60). Significantly higher stretch index values were reported when playing a top six opposition team when compared with the medium eight opposition teams. During losses, the stretch index was significantly higher when compared with wins and draws, respectively (&lt;i&gt;p&lt;/i&gt; = 0.01; &lt;i&gt;d&lt;/i&gt; = 1.47–1.89). Finally, the LpWratio values were significantly higher during periods when the team was losing, when compared with periods of drawing and winning (&lt;i&gt;p&lt;/i&gt; = 0.01; &lt;i&gt;d&lt;/i&gt; = 1.07–1.12).Conclusions.In conclusion, the spatiotemporal organisations of professional-level Brazilian club players are significantly influenced by contextual variables. The current findings support the use of GPS devices in soccer as a time-efficient and logistically viable method to characterise tactical behaviour and examine spatiotemporal movement patterns.

Contribution of deliberate practice, play, and futsal to the acquisition of decision-making skills in Brazilian professional female soccer players

ABSTRACT Previous research showed that deliberate practice and play contribute to developing decision-making skills in male soccer players. However, there is no evidence for female players. Therefore, this is the first study to analyse the contribution of deliberate practice, play, and futsal to develop decision-making skills in female soccer players. The purpose of this study was twofold: (1) to analyse whether elite Brazilian professional female soccer players with different levels of decision-making skills can be differentiated based on their engagement in various types and amounts of soccer activities during their development; (2) to discuss what sport's pathway in female soccer characterised the group with high decision-making skills. The sample comprised 77 Brazilian professional female soccer players. Decision-making skill was assessed based on a video-based test (TacticUP®). We used a retrospective questionnaire to collect information about previous participation in different soccer activities. We found differences among high skill (HS) and low skill (LS) decision-making groups regarding their participation in developmental activities in every period assessed (childhood, early, and late adolescence). In summary, we found that in every period set, the HS group accumulated more percentage time of their participation in soccer activities in practice compared to the LS group. Moreover, the HS group gathered more hours of practice in futsal and total practice (i.e., considering practice time in soccer and futsal) in early adolescence (13–15 years) compared to the LS group. We concluded that the specialised diversification pathway is the one that best characterises the sports involvement of better decision-makers during childhood.

Effects of match contextual factors on internal and external load in elite Brazilian professional soccer players through the season

This study aimed to investigate the effects of contextual match factors (quality of opposition, match outcome, change of head coach or playing style) on internal and external load in elite Brazilian professional soccer players, considering the total and effective playing time. Twenty-two professional male outfield soccer players participated in this study (age 28.4 ± 4.9years; height 1.78 ± 0.1cm; body mass 72.9 ± 7.1kg). The internal (rating of perceived exertion-based load [sRPE]) and external load (distance and accelerometry-based measures) were recorded during 38 matches, over the 2021 season of the Brazilian National 1st Division League using a global position system (10Hz) integrated with an accelerometer (200Hz). The main results were: (i) matches played against weak opponents presented greater values of sprinting distances compared to matches against intermediate and strong opponents; (ii) players covered greater high-intensity running distances when drawing than winning the matches; (iii) matches with assistant coaches presented higher mean speed relative to effective playing time (MSEPT) compared to coach 1 and coach 2 conditions. In addition, players covered greater MSEPT and high-acceleration in matches with coach 2 vs. coach 3; (iv) finally, small positive correlations were observed between positional attack sequences and MSTPT, total distance covered, and acceleration. Coaches and practitioners should consider these results when interpreting external load variables during elite Brazilian soccer matches.

Combined effect of game position and body size on network-based centrality measures performed by young soccer players in small-sided games.

This study verified the effects of body size and game position on interactions performed by young soccer players in small-sided games (SSG). The sample consisted of 81 Brazilian soccer players (14.4 ± 1.1 years of age). Height, body mass, and trunk-cephalic height were measured. SSG was applied in the GK + 3v3 + GK format, and Social Network Analyses were carried out through filming the games to obtain the following prominence indicators: degree centrality, closeness centrality, degree prestige, and proximity prestige, in addition to network intensity and number of goals scored. Factorial ANCOVA (bone age as covariate) was used to test the effects of game position, body size, and respective interaction on centrality measurements (p < 0.05). Similarity between game positions in body size indicators (p > 0.05) was observed. The game position affected degree centrality (p = 0.01, η2 = 0.16), closeness centrality (p = 0.01, η2 = 0.11), and network intensity (p = 0.02, η2 = 0.09), in which midfielders presented the highest network prominence values when compared to defenders and forwards. In conclusion, midfielders are players with high interaction patterns in the main offensive plays, which behavior is independent of body size.

Immediate Effects of Spinal Manipulative Therapy on the Performance of Elite Brazilian Soccer Players: A Pilot Randomized Controlled Trial With an Internally Validated Sham Treatment

ObjectiveThe purpose of this study was to assess the feasibility of the procedures’ routine, the recruiting rate, the presence of any significant detrimental impact on the players’ training routine, and the sham efficacy in achieving blinding. MethodsA parallel randomized controlled clinical trial was performed with 20 elite soccer players who were randomly assigned to 1 of 2 groups: spinal manipulative therapy (SMT) and sham SMT. All players were from the same team, were injury free, and were naive to SMT. Measured outcome tests (30-m sprint run with a 10-m split and change of direction [COD] test) were performed at the same time by all participants immediately before and after interventions. Photocell devices were used for data acquisition. ResultsTwenty participants were analyzed (10 in each group). There were no changes to the sprint (10 m and 30 m) and COD test results immediately after either of the interventions. All participants in both groups (SMT and sham SMT) answered “yes” to a question after the intervention asking if they were treated by SMT. No adverse effects or training routine impairment were reported. ConclusionThis pilot study protocol showed it was an appropriate design for a confirmatory clinical trial. The study had minimal effect on the team training routine, and the recruitment rate was excellent. The proposed sham SMT strategy was successful in blinding the players. In this sample, SMT did not have any immediate effect on the performance of these elite soccer players, as measured by 10- and 30-m sprint times and COD sprint times.

Adaptation and Validation of a Test for the Evaluation of Tactical Knowledge in Soccer: Test de Conocimiento Táctico Ofensivo en Fútbol for the Brazilian Context (TCTOF-BRA)

BackgroundStudies and tests to assess the tactical domain of young soccer players are recent, and few instruments meet the majority of quality criteria.ObjectiveTo adapt and validate the Test de Conocimiento Táctico Ofensivo en Fútbol (TCTOF) for the Brazilian context (TCTOF-BRA).MethodsThe article consists of two studies. Study 1 (n = 111) included the translation, theoretical/semantic analysis, back translation, cross-cultural equivalence, and content and face validity (pre-test). In study 2 (n = 768), a theoretical and empirical item analysis was carried out, followed by construct validity [exploratory factor analysis (EFA), confirmatory factor analysis (CFA), and the known-groups method] and reliability (internal consistency and repeatability).ResultsIn the cross-cultural evaluation, the Coefficient of content validity total (CCVt) of the instrument was 0.96 and in the content validity, the CCVt of the instrument was 0.87. The face validity was confirmed (>95%). After theoretical and empirical analysis, 15 questions were included in the Teste de Conhecimento Tático Ofensivo no Futebol (TCTOF-BRA). The EFA showed a model with adequate fit (KMO = 0.69; Bartlett p < 0.001), with a factor structure considered very good, composed of four factors (decision making, operational tactical principles, collective tactical-technical elements, and rules). The CFA by the Asymptotically Distribution-Free estimation method demonstrated good and very good goodness of fit indices (X2/df = 1.54, GFI = 0.99, CFI = 0.94, TLI = 0.92, PGFI = 0.71, PCFI = 0.76, RMSEA = 0.03, and ECVI = 0.26). The known-groups method showed significant differences (p < 0.01) and effect sizes varying from small-to-medium to large. With respect to reliability, coefficients of 0.89 (CR) and 0.74 (KR20) for internal consistency and 0.85 for repeatability were found.ConclusionThe TCTOF-BRA presented satisfactory evidence, demonstrating it to be an instrument with valid and reliable measures for the evaluation of tactical knowledge (declarative and theoretical procedural), based on specific knowledge and decision making (cognitive domain), of Brazilian young soccer players from 12 to 17.9 years old.

Within-subject variation of technical performance in elite Brazilian professional soccer players: the environmental stress, match location, and opposition’s ranking influences

ABSTRACT Recent research identified that the behaviour of players and teams varies depending on the match context affecting the players’ technical performance. Due to the high context variability of a soccer game, understanding the characteristics of technical performance in soccer can enable coaches to make better decisions. The present study aimed to evaluate the effects of environmental stress, match location, and opposition’s ranking on technical performance variation of elite soccer players from strong and weak teams from the Brasileirão Serie A (Brazilian First Division National Championship). Fourteen match actions were chosen as dependent variables in the analysis. Values of each action of each player per match were established. We compared the means of these values from the Top 4 and Bottom 4 teams across different match contexts (environment heat stress, match location, and opposition’s ranking). We calculated all comparisons using linear mixed models. The results showed better technical performance under low or medium environmental heat stress at home and against weak opposition (p < 0.05). Therefore, match context affects elite Brazilian soccer players’ technical performance from the first division championship.

Prevalence of abnormal electrocardiographic findings in a brazilian cohort of young football players: B-pro foot ECG pilot study

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Hospital de Clínicas de Porto Alegre Research and Event Incentive Fund (FIPE-HCPA) Introduction The 12-lead resting electrocardiogram is a useful tool for diagnosing pathological conditions in athletes. The prevalence of electrocardiographic abnormalities in Brazilian soccer players are unknown. Purpose To describe the prevalence of abnormal electrocardiographic findings in young Brazilian soccer players based on the "2017 International Criteria for Electrocardiographic Interpretation in Athletes". Methods Continuous variables were displayed as mean and standard deviation or median and interquartile range, while prevalence’s with 95% confidence intervals, and stratified by race. Intra-group differences were estimated by linear models or binomial and multinomial logistic regressions. Type I error was set to set a at 0.05. An additional margin of 0.025 was considered at the discretion of the statistician conditioned to the quality of the model. All analysis were running in Stata version 16.0.0. Results 2,581 young Brazilian soccer players from 27 clubs (mainly first division), aged 15-35 years (median: 18 years) were evaluated. 1,268 (49.1%) were Caucasians, 796 (30.8%) Mixed-Race (MR) and 517 (20.1%) Afro-Brazilians (AB). T-wave inversion (TWI) in the inferior leads (3.0%), high lateral leads (DI/aVL) (0.6%), V5 (2.3%), V6 (1.8%), and V5-V6 (1.7%) were present. Six Caucasians (0.5%) presented TWI in V1-V4. Prolonged corrected QT interval (QTc) (0.5%), QRS ≥140 ms (0.2%), "pathological" anterior Q waves (0.2%), lateral ST-segment depression (0.07%), premature ventricular contractions (0.5%), Mobitz type II atrioventricular block (0.03%), and a Wolff-Parkinson-White pattern (0.04%) were also observed. There were no athletes with short QTc interval, epsilon waves, profound sinus bradycardia (&amp;lt;30 beats per minute), complete left bundle branch block, third-degree atrioventricular block, or Brugada pattern (1, 2 or 3). Overall, 111/2,581 (4.3%) soccer players had electrocardiographic changes considered to be abnormal (4.4% in Caucasians, 4.5% in MR and 6.4% in AB). There was no difference between the abnormal findings among races, except for the prevalence of TWI in V6, which was higher in AB compared to Caucasians (3.1% versus 1.2%, respectively; P = 0.01). Conclusion To the best of our knowledge, this is the first large electrocardiographic cohort of Brazilian young soccer players to be described. In this sample, we evidence a prevalence &amp;lt;5% of abnormal findings according to the "2017 International Criteria for Electrocardiographic Interpretation in Athletes". Additional evaluation in all these cases is indicated.

Prevalence of Physiological Electrocardiographic Findings in a Brazilian Cohort of Young Football Players: B-Pro Foot ECG Pilot Study

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Hospital de Clínicas de Porto Alegre Research and Event Incentive Fund (FIPE-HCPA) Introduction The 12-lead electrocardiogram (ECG-12) is a useful tool in the assessment of athletes, and it may present findings compatible with physiological adaptations to regular exercise. ECG-12 findings in Brazilian soccer players are unknown. Purpose To describe the prevalence of physiological ECG-12 findings in young Brazilian soccer players based on the "2017 International Criteria for Electrocardiographic Interpretation in Athletes". Methods Continuous variables were displayed as mean and standard deviation or median and interquartile range, while prevalence’s with 95% confidence intervals, and stratified by race. Intra-group differences were estimated by linear models or binomial and multinomial logistic regressions. Type I error was set to set a at 0.05. An additional margin of 0.025 was considered at the discretion of the statistician conditioned to the quality of the model. All analysis were running in Stata version 16.0.0. Results 2,581 athletes from 27 clubs (mainly first division), aged 15-35 years (median: 18 years) were evaluated. 1,268 (49.1%) were Caucasians, 796 (30.8%) Mixed-race (MR) and 517 (20.1%) Afro-Brazilians (AB). In this sample from across the country, we identified the following findings and its respective prevalence: sinus bradycardia (50%), ectopic atrial rhythm (1.4%), junctional rhythm (0.3%), incomplete right bundle branch block (23.7%), first-degree atrioventricular (AV) block (3.0%), Mobitz type I AV block (0.1%), and increase QRS voltage for left or right ventricular hypertrophy (35.2% and 17.3%, respectively). The mean PR interval was 153.9±28.7 ms, corrected QT interval 399.2±28.0 ms, and QRS duration 96.0±14.0 ms. ST elevation followed by T-wave inversion in leads V1–V4 was identified in 11/517 (2.1%) of AB athletes. Early repolarization was present in 828 athletes (32.1%), being more prevalent in AB when compared to MR and Caucasians (P = 0.003). Likewise, AB had a greater PR interval in comparison to MR and Caucasians (P &amp;lt;0.001 and P = 0.007, respectively). On the other hand, Caucasians had a significant longer QRS duration compared to AB. For all remaining variables there was no difference among races. Conclusions To the best of our knowledge, this is the first large study to describe the prevalence of physiological electrocardiographic finding in young Brazilian soccer players, according to "2017 International Criteria for Electrocardiographic Interpretation in Athletes". Future studies comparing the frequency of these findings with the prevalence observed in other cohorts are welcome.