Elite Football Research Articles

Association between Selected Screening Tests and Knee Alignment in Single-Leg Tasks among Young Football Players.

This study aimed to examine the relationship between knee valgus in the frontal plane projection angle (FPPA) during single-leg squat (SLS), single-leg landing (SLL), and other selected clinical tests in young athletes. Forty-three young healthy elite football players (age: 13.2 (1.7) years) that were regularly training in a local sports club participated in the study. The FPPA was assessed using 2D video analysis. The screening tests included the passive single-leg raise (PSLR), hip external and internal rotation (hip ER and IR), sit and reach test, weight-bearing lunge test (WBLT), modified star excursion balance test (mSEBT), countermovement jump (CMJ), single-leg hop for distance (SLHD), and age peak height velocity (APHV). There was a significant positive relationship between the knee valgus angles in the SLS test and the sit and reach test (r = 0.34) and a negative relationship with the hip ER ROM (r = −0.34) (p < 0.05). The knee valgus angles in the SLL were negatively associated with the hip IR (r = −0.32) and ER ROM (r = −0.34) and positive associated with the WBLT (r = 0.35) and sit and reach test (r = 0.33) (p < 0.05). Linear regression analysis showed that the results of the hip ER ROM and sit and reach tests were independent predictors of the FPPA in the SLS test (r2 = 0.11, p = 0.03 and r2 = 0.12, p = 0.02, respectively). The conducted study showed that individuals with more hip range of motion, more spine flexion extensibility, and less ankle dorsiflexion ROM may be more likely to experience high degrees of knee valgus in FPPA.

Assessment of Body Composition and Physical Performance of Young Soccer Players: Differences According to the Competitive Level.

Simple SummaryIn recent years, soccer teams require greater physical and technical-tactical capabilities from not to younger players, especially in elite team. Although dribble and kicking skills, strength, endurance, speed, and agility abilities are the most relevant features, it is not clear whether anthropometric and body composition aspects could be considered appropriate talent characteristics in soccer players. In addition, it rests unclear which are the principal differences, when they appear, and what metrics discriminate between elite and non-elite teams. The main aim of this study is to compare anthropometric, body composition and physical performance between and within four juvenile categories of two (elite and non-elite) soccer teams and investigates factors that better discriminate among two teams. Despite the physical performance results as the most relevant factor in discriminating among the two soccer societies, the elite players report better anthropometric and body characteristics, especially in the youngest categories.Soccer is a multifactorial sport, in which players are expected to possess well developed physical, psychological, technical, and tactical skills. Thus, the anthropometric and fitness measures play a determinant role and could vary according to the competitive level. Therefore, the present study aimed to verify differences in body composition and physical performance between two soccer team. 162 young soccer players (from the Under 12 to Under 15 age categories; age: 13.01 ± 1.15 years) of different competitive levels (elite—n = 98 and non-elite—n = 64) were recruited. Anthropometric characteristics (height, weight, lengths, widths, circumferences, and skinfold thicknesses (SK)), bioelectrical impedance, physical performance test as countermovement jump (CMJ), 15 m straight-line sprints, Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo), and 20 + 20 m repeated-sprint ability (RSA)) were carried out. In addition, Body mass index (BMI), body composition parameters (percentage of fat mass (%F), Fat mass (FM, kg), and Fat-free mass (FFM, kg)) and the areas of the upper arm, calf and thigh were calculated, and the Bioelectric Impedance Vector Analysis (BIVA) procedures were applied. In addition, a linear discriminant analysis was assessed to determine which factors better discriminate between an elite and non-elite football team. Many differences were observed in body composition between and within each football team’s category, especially in triceps SK (p < 0.05), %F (p < 0.05), and all performance tests (p < 0.01). The canonical correlation was 0.717 (F(7,128) = 19.37, p < 0.0001), and the coefficients that better discriminated between two teams were 15 m sprint (−2.39), RSA (1−26), suprailiac SK (−0.5) and CMJ (−0.45). Elite soccer team players present a better body composition and greater physical efficiency. In addition, BIVA outcome could be a relevant selection criterion to scout among younger soccer players.

Effects of a competitive half-season on the aerobic capacity and match running performance of Turkish elite professional soccer players

This study examines how exertion during matches affects participants’ physical capacity and match performance. The study included 13 elite football league players (21 ± 0.7 years old; height, 181.1 ± 8.98 cm; body mass, 74.7 ± 8.1 kg) and used global positioning system (GPS) data collected during 12 official matches. Four matches after the first Yo-Yo IR1 test, four matches before the second Yo-Yo IR1 test, and four matches after the second Yo-Yo IR1 test are examined. Sprint count per minute (SC) (N/min), (&gt;19 km/h), p &lt; 0.030; distance covered at zone 4–6 per minute DCZ4 (km/h/min), (18–24 km/h), p &lt; 0.00; distance covered at zone 4–6 per minute DCZ5 (km/h/min), (24–30 km/h), p &lt; 0.001; and distance covered at zone 4–6 per minute DCZ6 (km/h/min), (30–39 km/h), p &lt; 0.001 were recorded. According to the values obtained before the tests, the match data show a decreasing trend in the following weeks. Furthermore, the relationship between physical performance values and tests is determined (average speed (AS) (km/h), r = 0.64; maximum speed (MS) (km/h), r = 0.50; DCZ4 (km/h/min), r = 0.89; DCZ5 (km/h), r = 0.81). As a result, time-dependent changes in intermittent endurance capacity during matches validated in-game running kinematics. This indicates the Yo-Yo IR1’s robustness as a fitness marker, and its capacity to help practitioners preview longitudinal variations in locomotor behavior during matches. Athletes who show a high degree of asymmetry in official matches seem to exhibit a strong ability to resist fatigue during testing.

Physical Demands during the Game and Compensatory Training Session (MD + 1) in Elite Football Players Using Global Positioning System Device.

The aims of this study were to analyze the differences of physical demands of non-starter players regarding the playing time during the competition and to evaluate the physical demands of the compensatory training (MD + 1C) for substitute players in elite football. The match statistics and MD + 1C of substitute players from a professional Spanish LaLiga football club were analyzed using a 10-Hz global positioning system (GPS) Apex GPS system device, which has been validated as a reliable and valid method to analyze performance in team sports, during all games of the 2016/2017, 2017/2018 and 2018/2019 seasons. The starting players showed both lower total distances covered and high-intensity actions compared to the substitutes. Regarding the minutes played by the substitutes, greater physical performance was found for the players with fewer minutes (5–15 min). Furthermore, no differences were found between first and second divisions regarding physical performance of substitutes (p > 0.05). This study highlights the importance of individualizing the workload of training sessions for substitutes and starters. Furthermore, the complementary session should be individualized according to the minutes played by the substitutes. These players are potentially under-loaded compared to starters, especially in terms of high-intensity actions, therefore additional session-specific training for each substitute would be useful to reach the optimal training load according to the minutes played during the game.

Modelling Changes in Bone and Body Composition Over a Season in Elite Male Footballers.

This study investigated the change in bone and body composition characteristics of elite football players and recreationally active control participants across the course of a season. Fortysix participants (20 footballers and 26 recreationally active controls) were assessed by dual-energy x-ray absorptiometry and peripheral Quantitative Computed Tomography for a range of bone and body composition characteristics at four points over the course of a competitive season. Multilevel modelling was used to examine changes. Footballers had higher characteristics than controls for 24 out of 29 dual-energy x-ray absorptiometry and peripheral Quantitative Computed Tomography variables (all p<0.05). However, there was also significant random inter-individual variation in baseline values for all variables, for both footballers and controls (p < 0.05). Wholebody bone mineral density, leg and whole-body bone mineral content, tibial bone mass and area (38%) increased across the season in footballers (p < 0.05), and there was significant random inter-individual variation in the rate of increase of leg and whole-body bone mineral content (p<0.05). Whole-body bone mineral density, leg and whole-body bone mineral content, tibial bone mass and area (38%) increased over the course of the season in elite football players. The modelling information on expected changes in bone characteristics provides practitioners with a method of identifying those with abnormal bone response to football training and match-play.

Prognostic factors of muscle injury in elite football players: A media-based, retrospective 5-year analysis

ObjectivesMotor function has been demonstrated to be weakly predictive for the occurrence of muscle injury in team sports. This study examined the value of non-motor prognostic factors in elite football (soccer). DesignRetrospective cohort study. SettingAnalysis of a public data register (Transfermarkt.com). Participants1148 players of 38 German and English first-division football clubs. Main outcome measuresBinary logistic regression examining the association of prognostic factors (age, height, weight, BMI, playing position, market value, history of injury, number of played matches and minutes) and time-loss muscle injuries sustained during five consecutive seasons (2014/2015 to 2018/2019). ResultsA total of 1722 muscle injuries were observed in 619 players. History of general musculoskeletal injury (OR 5.3, 95% CI 3.8–7.5), playing position (OR 2.4–2.5), market value (OR 2.3, 95% CI 1.7–3.1), and history of muscle injury (OR 1.6, 95% CI 1.1–2.2) were associated with muscle injury. Sub-analyses revealed location-specific patterns. Playing position was not predictive for adductor injury and, except for one weak association (defender vs. goalkeeper: OR 1.05, 95%CI 0.42–2.62), the same applied to the calf. Contrary to other locations, thigh re-injury was not predicted by previous muscle injury. ConclusionsNon-motor factors display significant associations with injury risk in elite football players. Conditioning coaches may use this information to improve primary and secondary prevention, while scouting departments may benefit during recruitment.

Heading Exposure in Elite Football (Soccer): A Study in Adolescent, Young Adult, and Adult Male and Female Players.

ABSTRACTPurposeThis study aims to quantify heading exposure in real-life elite football at the level of individual male and female adolescents, young adults, and adults.MethodsHeading exposure was determined by video analysis in combination with a structured electronic registration tool and observation training, to comprehensively register heading characteristics. Characteristics of heading events were registered in 116 official matches (96 male, 20 female) of Dutch national teams.ResultsMean exposure for male players based on full match participation was 4.2 headers, with maximum heading exposure at 10.6 headers. Mean heading exposure was higher in adult than adolescent players (P = 0.049), whereas maximum heading exposure was higher for adult than for young adult players (P = 0.045). Maximum heading exposure was higher in male than in female players (P = 0.015). Defenders had the greatest mean and maximum heading exposure (P < 0.001). Longer flight courses of the ball had greater contribution to mean and maximum heading exposure than shorter courses (P < 0.01). Frontal headers had greater contribution to exposure than other points of contact on player’s head (P < 0.001), whereas linear headers had greater contribution than rotational headers (P = 0.016). Defensive headers had greater contribution to exposure than other heading types (P < 0.014). Unintentional head contacts in elite football players were, in most cases (80%), not related to heading situations.ConclusionsThis study provides real-life quantifications of mean and maximum heading exposure in elite football, with strong relevance for policy makers and researchers. The results highlight the roles of player and heading characteristics in heading exposure, informing current discussions on the role of heading in football.

COVID-19 Infection among Elite Football Players: A Nationwide Prospective Cohort Study.

Little is known about the risk of COVID-19 infection among footballers. We aimed to investigate the incidence and characteristics of COVID-19 infection among footballers. In total, 480 football players of Super League Greece and 420 staff members participated in a prospective cohort study, which took place from May 2020 to May 2021. Nasopharyngeal swabs were collected from footballers and staff members weekly. All samples (n = 43,975) collected were tested using the reverse transcriptase polymerase chain reaction (RT-PCR) test for the detection of “SARS-CoV-2”. In total, 190 positive cases (130 among professional football players and 60 among staff) were recorded. Out of the 190 cases that turned positive, 64 (34%) cases were considered as symptomatic, and 126 (66%) cases were asymptomatic. The incidence rate of a positive test result for footballers was 0.57% (confidence interval (CI) 0.48–0.68%) and for staff members it was 0.27% (CI 0.20%, 0.34%), respectively. Footballers recorded a twofold increased risk of COVID-19 infection in comparison to staff members (relative risk = 2.16; 95% CI = 1.59–2.93; p-value < 0.001). No significant transmission events were observed during the follow-up period. We found a low incidence of COVID-19 infection among professional footballers over a long follow-up period. Furthermore, the implementation of a weekly diagnostic testing (RT-PCR) was critical to break the transmission chain of COVID-19, especially among asymptomatic football players and staff members.

Incidence and Clinical Relevance of COVID-19 in a Population of Young Competitive and Elite Football Players: A Retrospective Observational Study

BackgroundThe COVID-19 pandemic dramatically changed lifestyle worldwide, including sport. A comprehensive evaluation of the prevalence of cardiac involvement in COVID-19 is essential to finalize a safe protocol for resuming elite sport. The aim of this study is to evaluate incidence of cardiac involvement and COVID-19 impact on athletic performance.Materials and methodsThis retrospective observational study analysed the data collected from consecutive competitive athletes who performed medical-sports examinations at the J Medical Center from March 2020 to March 2021. All athletes periodically performed a molecular test using a nasopharyngeal swab to detect COVID-19 infection. Positive athletes performed laboratory (cardiac troponin T—cTnT) and instrumental (echocardiography, stress test, Holter ECG) investigations following recovery to identify any cardiac involvement. Cardiac magnetic resonance imaging (MRI) was performed in case of abnormal findings at first-level evaluation.ResultsAmong 238 athletes (median age 20 years), 77 contracted COVID-19, mainly males (79%) with a median age of 16 years. Fifty-one athletes (66%) presented mild symptoms, and none required hospitalization. Evaluation for resuming sport was performed after a median of 30 days from the first positive test. Abnormal findings were obtained in 13 cases (5 athletes [6%] with elevated cTnT values; 13 athletes [17%] with arrhythmias on Holter ECG and/or during stress test; 2 athletes [3%] anomalies at echocardiography). Cardiac MRI discovered abnormalities in 9 cases, but none of these was clearly related to COVID-19 and none fulfilled acute myocarditis criteria. No negative impact on athletic performance was observed, and none of the athletes developed persistent COVID-related symptoms.ConclusionsOur registry confirms the predominantly self-limiting illness in young athlete population. The incidence of clear COVID-19-related structural myocardial injury was very low, but transient exertional ventricular arrhythmias or pericardial effusion was observed without significant impact on athletic performance. Implemented screening for return to activity is likely reasonable only in moderate-to-severe symptomatic athletes.

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

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

How spatial constraints afford successful and unsuccessful penetrative passes in elite association football

ABSTRACT Background The aim of the present study was to examine the spatial relations between teams (macro-level) and groups of players (meso-level) that afford successful penetrative passes (off-ball advantage) in elite football. Methods Three balanced home matches from a Premier League team with 91 ball possessions in which a pass was performed into the opposition defensive area and overpassed the first defensive line, promoting a perturbation of the defensive team equilibrium, were selected for analysis. The spatial relations between teams were measured through spatial variables that captured the areas occupied by the teams, while the spatial relations between players were measured through variables that captured the distances and angles between attacking and defending players near the ball. Results Results revealed, at the macro-level, higher values of width ratio between teams and the width of the attacking team for unsuccessful penetrative passes (UPP), when compared to successful penetrative passes (SPP). At the meso-level, a general decrease in distances and an increase in angles between attacking and defending players were observed between successful to unsuccessful penetrative passes. Conclusions These findings highlight the importance of using positional data analysis to identify teams’ tactical profiles and to potentiate coaches’ interventions.

Platelet Activation Favours NOX2-Mediated Muscle Damage in Elite Athletes: The Role of Cocoa-Derived Polyphenols.

Mechanisms of exercise-induced muscle injury with etiopathogenesis and its consequences have been described; however, the impact of different intensities of exercise on the mechanisms of muscular injury development is not well understood. The aim of this study was to exploit the relationship between platelet activation, oxidative stress and muscular injuries induced by physical exercise in elite football players compared to amateur athletes. Oxidant/antioxidant status, platelet activation and markers of muscle damage were evaluated in 23 elite football players and 23 amateur athletes. Compared to amateurs, elite football players showed lower antioxidant capacity and higher oxidative stress paralleled by increased platelet activation and muscle damage markers. Simple linear regression analysis showed that sNOX2-dp and H2O2, sCD40L and PDGF-bb were associated with a significant increase in muscle damage biomarkers. In vitro studies also showed that plasma obtained from elite athletes increased oxidative stress and muscle damage in human skeletal muscle myoblasts cell line compared to amateurs’ plasma, an effect blunted by the NOX2 inhibitor or by the cell treatment with cocoa-derived polyphenols. These results indicate that platelet activation increased muscular injuries induced by oxidative stress. Moreover, NOX2 inhibition and polyphenol extracts treatment positively modulates redox status and reduce exercise-induced muscular injury.

Relationship between Explosive Strength With Speed and Agility among U-12 Football Athletes

To excel in football, speed and agility are the key elements of fitness. Thus, some combinations of strength, power and plyometric training have been applied in order to enhance both components. There are some studies that found the positive correlations between explosive strength with both speed and agility components that led to the finding which suggested that improving muscle strength and power may help to turn these changes into reducing in time for sprinting and the ability to change direction for athletes. However, the studies about this relationship on youth football athletes have been limited especially for youth football athletes in Malaysia. Thus, this study aimed embarking to discover the correlation between explosive strength with speed and agility among U-12 football athletes in Malaysia. This study was divided into three tests which included standing broad jump, 30m sprint and 10m agility shuttle test. Twenty-six U12 elite football players were equally assigned in this study. This study uses a correlational test design which is Pearson Correlation to evaluate the relationship between standing broad jump with 30m sprint and 10m agility shuttle test. The result for correlation between standing broad jump and 30m sprint shown a non-significant correlation, (r=-.368, p=.064) while the result for correlation between standing broad jump and 10m agility shuttle test shown a significant correlation, (r=-.570, p=.002). Overall, this research highlighted that agility was affected by explosive strength while sprint was not affected by explosive strength among U12 football players in Malaysia.

Perceptions of role ambiguity for Sporting Directors in professional football

ABSTRACT The Sporting Director is one strategy football clubs have adopted to protect their financial sustainability. Little to no research has been undertaken on the Sporting Director role in football. This article draws upon a qualitative methodology to examine perceptions and practices related to the role and its potential implications in football’s growing global business. Semi-structured interviews were undertaken with senior stakeholders in football (N = 21). The data was thematically analysed. Findings indicate that the Sporting Director role would be a strategic benefit for football clubs, however several issues related to role ambiguity. The novel empirical insight surrounds three key themes, notably the perception of the role, job description clarity and communication. The study provides novel insights into the elite football stakeholder perceptions of the Sporting Directors. This research offers decision-makers considerations for developing the Sporting Director role in football and recommendations for future research.

Professional football training strategies during home confinement in the COVID-19 pandemic

SARS-CoV-2 emergency forced athletes to train at home on their own and mostly unsupervised, making it difficult to provide training solutions. The aims of the study were 1) to collect data and experiences from a Serie A male football team, a top-level female football team and a male young elite football team; 2) to compare data from lockdown and pre-lockdown period; 3) to report changes in training strategies adopted to overcome logistical constraints and 4) to evaluate their congruence to cardio, strength and stretching recommendation mentioned above; 5) to report compliance through player daily feedback. Three different professional football teams were enrolled. From March 16, 2020 to April 13, 2020, data for each team were recorded weekly and compared to a standard training period (October 15th to November 15th, 2019) from the same groups. The rate of perceived exertion (RPE), Visual Analogue Scale (VAS) and Total Quality of Recovery Scale (TQR) values were used to compare the two periods using The Student t-Test and Pearson Test. Each group chose a different training approach. Between the pre-lockdown and the lockdown period, there was no significant difference in the VAS, TQR and RPE indexes. Other else players' compliance differed between the groups during the lockdown period. Most athletes maintained a high level of training during the COVID-19 forced isolation, thanks to the help of team athletic trainers who provide functional tools and indications customized for each differ. Athletes' feedback and compliance differed according to their gender and age. Monitoring with live video sessions and social group sharing among younger players improved compliance and aggregation.

Time to return to full training and recurrence of rectus femoris injuries in elite track and field athletes 2010-2019; a 9-year study using the British Athletics Muscle Injury Classification.

Rectus femoris (RF) injuries are common in sports requiring maximal acceleration and sprinting. The British Athletics Muscle Injury Classification (BAMIC) describes acute muscle injury based on the anatomical site of injury and has been associated with return to play in hamstring and calf muscle injury. The aim of this study was to describe and compare the time to return to full training (TRFT) and injury recurrence for BAMIC-classified RF injuries sustained by elite track and field (T&F) athletes over a 9-year period. All rectus femoris injuries sustained by elite T&F athletes on the British Athletics World Class Program between September 2010 and September 2019 that were investigated with an MRI within 7days of acute onset anterior thigh pain were included. Injuries were graded from the MRI by a specialist musculoskeletal radiologist using the BAMIC, and TRFT and injury recurrence were determined by evaluation of the Electronic Medical Record. Athlete demographics and World Athletics event discipline were recorded. Specific injury details including mechanism, location of injury, and whether surgical or rehabilitation management was undertaken were recorded. There were 38 RF injuries in 27 athletes (24.7±2.3years; 10male, 17 female). Average TRFT for rehabilitation managed cases was 20.4±14.8days. Grade 1 injuries had significantly shorter TRFT compared with grades 2 (p=0.04) and 3 (p=0.01). Intratendinous (c) and surgically managed RF injuries each had significantly longer TRFT compared with other injury classes (p<0.001). Myofascial (a) injuries had reduced repeat injury rates compared with b or c classes (p=0.048). Grade 3 injuries had an increased repeat injury rate compared with other grades (p=0.02). There were 4 complete (4c) proximal free tendon injuries sustained during sprinting and all in female athletes. The average TRFT for RF injuries in elite T&F is similar to that previously identified in elite football and Australian Rules. Similar to previous research in hamstring and calf injury, RF injuries extending into the tendon (BAMIC class c) had delayed TRFT which may reflect the longer duration required for tendon healing and adaptation. Grade 3 injuries had in increased repeat injury rate compared with grades 1 and 2. The BAMIC diagnostic framework may provide useful information for clinicians managing rectus femoris injuries in T&F.

Small-Sided Games in Elite Football: Practical Solutions to Replicate the 4-min Match-Derived Maximal Intensities.

Riboli, A, Esposito, F, and Coratella, G. Small-sided games in elite football: practical solutions to replicate the 4-min match-derived maximal intensities. J Strength Cond Res 37(2): 366-374, 2023-The purpose of the study was to determine the area per player (ApP, m 2 ·player -1 ) to replicate the maximal 4-min match-play period (4-min Peak ) using small-sided or large-sided games (SSGs) lasting the same duration in elite football players. Twenty players (age: 26 ± 5 years) competing in European championship and international UEFA competitions were monitored during SSGs with (SSG with ) or without (SSG without ) goalkeepers, both lasting 4-min. A total of 1,724 and 561 individual observations for SSG with and SSG without across 99 and 34 different SSGs formats were undertaken. Whole (90-min avg ) and 4-min Peak match demands were calculated. Relative (m·min -1 ) total, high-speed (HSRD), very high-speed (VHSRD), sprint, and acceleration/deceleration distance were collected. For both SSG with and SSG without , ApP was small -to- very-largely correlated with TD, HSRD, VHSRD, and sprint, whereas an inverse trivial -to- small correlation with acceleration/deceleration was found. In SSG with , the ApP to replicate 4-min Peak was larger ( p < 0.001, effect size [ES]: 0.33-5.80) than that to mimic 90-min avg for total distance, HSRD, VHSRD, and sprint, whereas for acceleration/deceleration the ApP was lower ( p < 0.001, ES: -3.13 to 0.48) for 4-min Peak . In SSG without , the ApP to replicate 4-min Peak was larger ( p < 0.001, ES: 0.04-3.72) than that to mimic 90-min avg for HSRD, VHSRD, and sprint. Some positional differences ( p < 0.05, ES: 0.22-1.10) in ApP were found. The ApP to replicate 4-min Peak was higher for SSG with than SSG without ( p < 0.001, ES: 0.67-3.58). These findings may help practitioners to recreate the 4-min Peak to manage ApP during SSGs in elite football.

Time to change direction in training load monitoring in elite football? The application of MEMS accelerometers for the evaluation of movement requirements

ABSTRACT In elite football, the emphasis is placed on monitoring the output from the Global Positioning Systems (GPS) component of a Micro-Electro-Mechanical Systems (MEMS) device; however, this does not comprehensively overview the total demands due to the intermittent multidirectional nature. The aim of the study was to investigate the application of accelerometer data provided by MEMS, to evaluate movement requirements in elite football. A two-staged research approach, involving an effectiveness and efficacy stage, was deployed. The effectiveness stage examined two MEMS-accelerometer variables (PlayerLoadTM (PL) and PlayerLoadTM per meter (PL.m−1)) for four years and four months. Ninety-nine English Premier League outfield football players’ participated. In the efficacy stage, 26 elite outfield football players completed three different training modalities (running, possession and dribbling) and a range of MEMS-accelerometer variables were analysed. In the effectiveness stage, the mean difference in PL for all training activities other than Set Pieces were similar to Matches (−283 to −246au). Model coefficients for PL.m−1 were smallest in Team Shape (−0.00114au), Attacking (0.00025au) and Games (0.00196au), and largest for Possession (0.03356AU), Defending (0.03182au) and Skills Games (0.03106au) compared to Matches. The findings suggest that PL.m−1 but not PL may be effective at describing differences in movement requirements. In the efficacy stage, PL.m−1 and inertial movement analysis (IMA) efforts were the only variables that had greater mean differences in the smaller conditions, confirming PL.m−1’s suitability in evaluating movement requirements of different training activities and pitch dimensions. The findings suggest such a variable offers value in a monitoring strategy in football.

Body Pose Estimation Integrated With Notational Analysis: A New Approach to Analyze Penalty Kicks Strategy in Elite Football.

Body orientation of football players has proven to be an informative resource related to successful penalty kicks. OpenPose is one of the most popular open-source pose estimation technologies. This study aims: (i) to verify whether OpenPose can detect relevant body orientation angles from video data of penalty kicks in elite football and (ii) to investigate the relationship between these body angles and observable behaviors analyzed via an observational system for penalty kick analysis in football (OSPAF) with the penalty taker and goalkeeper strategy. A total of 34 penalty videos, with standardized viewing angle, from the main European leagues (2017–2020) were analyzed. Relevant body orientation variables were selected for penalty kicks analysis and were extracted from video data through OpenPose technique. The OSPAF, previously validated by experts, was used. The mean confidence score of OpenPose measures was 0.80 ± 0.14. OpenPose Retest reliability values was 0.976 ± 0.03. Logistic regressions were performed to investigate the relationship between OpenPose investigated variables (penalty taker: shoulder, hips, and nonkicking foot orientation; goalkeeper: right and left foot, anticipation), observable behaviors (OSPAF variables), and the strategy (penalty taker: goalkeeper dependent or independent; goalkeeper: shooter dependent or independent) in penalty kicks. The selected body orientation angle (goalkeeper anticipation) measured through OpenPose correlated significantly with the goalkeeper strategy. The prediction model of the goalkeeper's strategy had its accuracy increased to 97% when the variable goalkeeper anticipation was included [ = 49.648, p < 0.001]. Lower degrees of goalkeeper anticipation, the goalkeeper tactical action (awaiting), and run up speed (slow) were associated with a kicker-dependent strategy. Regarding the penalty taker, the selected body angles measured through OpenPose did not associate significantly with the shooter strategy. Body orientation analysis by using OpenPose has shown sufficient reliability and provides practical applications for analyzing the strategies adopted by goalkeepers in penalty kicks in elite football.

Osgood-Schlatter Disease in youth elite football: Minimal time-loss and no association with clinical and ultrasonographic factors

BackgroundOsgood-Schlatter Disease is the most common cause of knee pain in youth. Scientific research in youth elite football is limited. ObjectivesTo assess clinical and ultrasonographic factors associated with Osgood-Schlatter Disease and calculate point prevalence of clinical diagnosis and time-loss in youth elite male football. Study designNested case-control study and cross-sectional prevalence study; Level of evidence: 3. MethodsWe obtained data during the pre-season periodic health evaluation. Osgood-Schlatter Disease diagnosis was defined as (1) athlete-reported anterior knee pain and (2) clinical confirmation by pain provocation at the tibial tuberosity. Time-loss was defined as inability to participate in team training and/or competition.For the nested-case control study, we examined clinical and ultrasonographic factors in the U13 to U16 teams. We matched on calendar-age. The clinical factors were: self-reported history of Sever's disease, growth measures, leg muscles flexibility and strength and ultrasonographic bone maturity stages according to Ehrenborg, For the cross-sectional study, we included players of the U13 to U19 teams to calculate the point prevalence. ResultsThe case-control study consisted 30 players and the cross-sectional study 127 players. Previous Sever's disease was strongly associated with Osgood-Schlatter Disease (OR = 16.8; p = 0.02; 95% CI = 1.6–174.5). None of the other clinical or ultrasonographic factors were associated. The point prevalence was 17% and 80% had no time-loss despite presence of clinical symptoms. ConclusionConsidering the 16.8OR, previous Sever's disease indicates a strong association with Osgood-Schlatter Disease. Although generally suggested, growth velocity and bone maturity are not associated in an age-matched comparison.