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OBJECTIVES: To assess measurement agreement between FELS and Tanner-Whitehouse (TW) II skeletal ages in male youth soccer players from the Middle East. METHODS: We examined agreement between FELS and TW-II skeletal ages using data collected between- and within-subjects (n = 1057 observations) for 409 male, full-time, academy student-athletes recruited as part of the Qatar Football Association national soccer development programme (chronological age range, 9.8 to 18 years; annual screening range, one to seven visits). The Bland-Altman method for repeated measurements estimated the limits of agreement describing the expected range of differences for 95% of pairs of future FELS and TW-II skeletal ages determined on similar individuals from the reference population. RESULTS: The mean difference for TW-II versus FELS protocols was 0.02 years (95% confidence interval, -0.04 to 0.08 years) with lower and upper limits of agreement ranging from -1.39 years (95% confidence interval, -1.48 to -1.30 years) to 1.43 years (95% confidence interval, 1.34 to 1.52 years). CONCLUSION: Differences for 95% of pairs of future skeletal ages determined with FELS and TW-II methods in this population could be as high as ~3 years for some people that suggested protocols may not be interchangeable in youth Middle Eastern athletes. Justification of skeletal age protocol selection rests on knowledge of measurement bias and variability of expected growth estimations for rationalized application to a population of interest.
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Futebol , Humanos , Masculino , Adolescente , Criança , Determinação da Idade pelo Esqueleto/métodos , Atletas , Oriente MédioRESUMO
OBJECTIVES: To examine the timing and intensity of skeletal maturation of the radius-ulna-short (RUS) bones in elite youth Arab athletes. METHODS: We compared SuperImposition by Translation And Rotation (SITAR) models with different spline degrees of freedom and transformation expressions to summarize 492 longitudinal measurements for individual RUS bones scores assessed from 99 male academy student-athletes (chronological age range, 11.4 to 18 years; annual screening range, four to seven visits). RESULTS: The SITAR model with 5 degrees of freedom and untransformed chronological age was superior to the other models. The mean growth curve increased with age and showed a mid-pubertal double-kink at a RUS score of ~600 bone score units (au). The SITAR model revealed a first peak in the skeletal maturation velocity curve of ~206 au·year-1 occurred at ~13.5 years. The mean age at the second and largest peak occurred at 15.1 years (95% confidence interval [CI], 14.9 to 15.3 years), with the respective estimated peak skeletal ossification rate of 334 au·year-1 (95% CI, 290 to 377 au·year-1 ). The mean age at peak height velocity was 13.5 years (95% CI, 13.3 to 13.7 years), with peak height velocity of 10 cm·year-1 (95% CI, 9.6 to 10.4 cm·year-1 ). CONCLUSION: Application of the SITAR method confirmed two peaks in the skeletal maturation velocity curve, with the second and largest rate of ossification occurring at a relatively later timing of ~1.5 years than the height growth spurt. Knowledge of the RUS bones timing and intensity can be important to advance strategies for athlete performance development purposes.
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Osteogênese , Puberdade , Humanos , Masculino , Adolescente , Criança , Atletas , Estatura , ÁrabesRESUMO
PURPOSE: To assess conventional assumptions that underpin the percentage of mature height index as the simple ratio of screening height (numerator) divided by actual or predicted adult height (denominator). METHODS: We examined cross-sectional data from 99 academy youth soccer players (chronological age range, 11.5 to 17.7 y) skeletally immature at the screening time and with adult height measurements available at follow-up. RESULTS: The y-intercept value of -60 cm (95% confidence interval, -115 to -6 cm) from linear regression between screening height and adult height indicated the failure to meet the zero y-intercept assumption. The correlation coefficient between present height and adult height of .64 (95% confidence interval, .50 to .74) was not equal to the ratio of coefficient of variations between these variables (CVx/CVy = 0.46) suggesting Tanner's special circumstance was violated. The non-zero correlation between the ratio and the denominator of .21 (95% confidence interval, .01 to .39) indicated that the percentage of mature height was biased low for players with generally shorter adult height, and vice versa. CONCLUSION: For the first time, we have demonstrated that the percentage of mature height is an inconsistent statistic for determining the extent of completed growth, leading to potentially biased inferences for research and applied purposes.
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Estatura , Futebol , Adolescente , Humanos , Criança , Estudos TransversaisRESUMO
ABSTRACT: Kyprianou, E, Di Salvo, V, Lolli, L, Al Haddad, H, Villanueva, AM, Gregson, W, and Weston, M. To measure peak velocity in soccer, let the players sprint. J Strength Cond Res 36(1): 273-276, 2022-Expressing externals loads relative to a player's individual capacities has potential to enhance understanding of dose-response. Peak velocity is an important metric for the individualization process and is usually measured during a sprint test. Recently, however, peak velocity was reported to be faster during soccer matches when compared with a 40-m sprint test. With the aim of developing the practice of individualized training prescription and match evaluation, we examined whether the aforementioned finding replicates in a group of elite youth soccer players across a broader range of soccer activities. To do this, we compared the peak velocities of 12 full-time male youth soccer players (age 16.3 ± 0.8 years) recorded during a 40-m sprint test with peak velocity recorded during their routine activities (matches, sprints, and skill-based conditioning drills: small-sided games [SSG], medium-sided games [MSG], large-sided games [LSG]). All activities were monitored with 10-Hz global positioning systems (Catapult Optimeye S5, version 7.32) with the highest speed attained during each activity retained as the instantaneous peak velocity. Interpretation of clear between-activity differences in peak velocity was based on nonoverlap of the 95% confidence intervals for the mean difference between activities with sprint testing. Peak velocity was clearly faster for the sprint test (8.76 ± 0.39 m·s-1) when compared with matches (7.94 ± 0.49 m·s-1), LSG (6.94 ± 0.65 m·s-1), MSG (6.40 ± 0.75 m·s-1), and SSG (5.25 ± 0.92 m·s-1), but not sprints (8.50 ± 0.36 m·s-1). Our data show the necessity for 40-m sprint testing to determine peak velocity.
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Desempenho Atlético , Corrida , Futebol , Adolescente , Coleta de Dados , Sistemas de Informação Geográfica , Humanos , MasculinoRESUMO
The aim was to investigate the preventive effect of a complex training program based on holistic hamstring health understanding in elite professional soccer players. This study involved an elite club in Europe and was conducted over 12 seasons. The last 2 seasons were the intervention period, and the others were the control seasons. During the intervention period, players performed a complex program organized into different interventions throughout the week having as a priority the player health. Hamstring injuries, absenteeism, injury rates, and injury burden between the control and intervention seasons were compared using a rate ratio (RR) with 95% CI. Players had a mean exposure of 333.5 ± 18.6 hours per season with no significant differences between the intervention and control seasons. The overall injury rate was 3 times lower during the two intervention seasons than during the previous seasons (P < .01); the match injury rate was 2.7 times lower (P < .01) and the training rate 4.3 times (P < .01). Injury burden was almost 4 times lower during the two intervention seasons than during the previous seasons (P < .01), and recurrences in the control group were 10% vs 0% in the intervention group. Hamstring injuries were reduced ~3 times during the seasons in which elite football players were exposed to multicomponent, complex prevention training with individual approaches based on player needs, management of training load, individualized physiotherapy treatment, and planned staff communication, in comparison to the control seasons without a clearly defined and structured injury prevention intervention.
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Traumatismos em Atletas/prevenção & controle , Exercício Físico/fisiologia , Músculos Isquiossurais/lesões , Traumatismos da Perna/prevenção & controle , Treinamento Resistido/métodos , Futebol/lesões , Traumatismos em Atletas/epidemiologia , Europa (Continente)/epidemiologia , Humanos , Traumatismos da Perna/epidemiologia , MasculinoRESUMO
OBJECTIVES: To describe age group patterns for injury incidence, severity and burden in elite male youth football. METHODS: Prospective cohort study capturing data on individual exposure and time-loss injuries from training and matches over four seasons (2016/2017 through 2019/2020) at a national football academy (U13-U18; age range: 11-18 years). Injury incidence was calculated as the number of injuries per 1000 hours, injury severity as the median number of days lost and injury burden as the number of days lost per 1000 hours. RESULTS: We included 301 players (591 player-seasons) and recorded 1111 time-loss injuries. Overall incidence was 12.0 per 1000 hours (95% CI 11.3 to 12.7) and burden was 255 days lost per 1000 hours (252 to 259). The mean incidence for overall injuries was higher in the older age groups (7.8 to 18.6 injuries per 1000 hours), while the greatest burden was observed in the U16 age group (425 days; 415 to 435). In older age groups, incidence and burden were higher for muscle injuries and lower for physis injuries. Incidence of joint sprains and bone stress injuries was greatest for players in the U16, U17 and U18 age groups, with the largest burden observed for U16 players. No clear age group trend was observed for fractures. CONCLUSION: Injury patterns differed with age; tailoring prevention programmes may be possible.
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Futebol , Adolescente , Criança , Humanos , Masculino , Absenteísmo , Distribuição por Idade , Fatores Etários , Atletas , Incidência , Escala de Gravidade do Ferimento , Estudos Prospectivos , Catar/epidemiologia , Estações do Ano , Futebol/lesões , Futebol/estatística & dados numéricos , Fatores de Tempo , Esportes Juvenis/lesões , Esportes Juvenis/estatística & dados numéricosRESUMO
Training and competition loads have emerged as modifiable composite risk factors of non-contact injury. Hamstring strains are the most common injuries in football with substantial burden on the individual player and club. Nevertheless, robust evidence of a consistent load-hamstring injury relationship in professional football is lacking. Using available data from the Qatar Stars League over three competitive seasons, this study investigated the separate and combined effects of perceived exertion and session duration on hamstring injury occurrence in a sample of 30 outfield football players. Load variables were calculated into 7-day, 14-day, 21-day, 28-day periods of data, and week-to-week changes for average ratings of perceived exertion (RPE; au) score and session-RPE (s-RPE; session-duration × score), plus the cumulative training and match minutes and s-RPE, respectively. Conditional logistic regression models estimated load-injury relationships per 2-within-subject standard deviation increments in each candidate variable. Associations were declared practically important based on the location of the confidence interval in relation to thresholds of 0.90 and 1.11 defining small beneficial and harmful effects, respectively. The uncertainty for the corrected odds ratios show that typically high within-subject increments in each candidate variable were not practically important for training- and match-related hamstring injury (95% confidence intervals range: 0.85 to 1.16). We found limited exploratory evidence regarding the value of perceived exertion and session duration as etiological factors of hamstring injury in Middle-East professional football. Monitoring remains valuable to inform player load management strategies, but our exploratory findings suggest its role for type-specific injury risk determination appears empirically unsupported.
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Traumatismos em Atletas/etiologia , Músculos Isquiossurais/lesões , Futebol/lesões , Carga de Trabalho , Atletas , Humanos , Masculino , Catar , Fatores de Risco , Fatores de TempoRESUMO
Talent identification (TID) and development (TDE) are large fields in professional soccer and in science. However, TID and TDE processes in youth academies have not been assessed in detail. As such, our aim was to survey professional clubs from around the world about their youth academy TID and TDE processes, with 29 clubs responding to the survey. TID and TDE processes changed as a function of player age. TID processes involved finding the best players locally and regionally, but for older players the search widened to nationally and internationally for the needs of the first team. Clubs used a multidisciplinary approach to TID, but more so with older players. Median number of academy players was 80, 100, and 66 players at 8-11 years, 12-16 years, and 17-21 years, respectively. Annual player turnover in the most recent season (selections/de-selections) was 29% across all age groups, with competition from other clubs cited as a limitation to TID. TDE processes involved weekly matches and 3-5 training sessions per week led by experienced, well-qualified coaches, with most clubs providing players with academic education, residency and transportation services. Our findings extend previous research assessing professional soccer youth academy TID and TDE processes by quantifying worldwide practices.
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Aptidão , Desempenho Atlético/fisiologia , Tutoria , Futebol/fisiologia , Adolescente , Criança , Tomada de Decisões , Educação , Habitação , Humanos , Masculino , Condicionamento Físico Humano , Desenvolvimento de Programas , Adulto JovemRESUMO
This study determined the most effective field method for quantifying fat-free mass (FFM) in elite youth male soccer players compared to dual X-ray absorptiometry (DXA) values and to develop prediction equations for FFM based on anthropometric variables. Forty-one male elite-standard youth soccer players, ages 16.2-18.0 years, undertook FFM assessments including bioelectrical impedance analysis, and different skinfold-based prediction equations. DXA provided a criterion measure of FFM. Correlation coefficients, bias, limits of agreement, and differences were used as validity measures, and regression analyses to develop soccer-specific prediction equations. Slaughter et al (1988), Durnin and Wormersley (1974), and Sarria et al (1998) equations showed the lowest biases, and no significant, standardized, and substantial differences against DXA. The new youth soccer-specific anthropometric equation explained 91% of the DXA-derived FFM variance using three circumferences, eight skinfolds, and one bone breadth. All field methods compared in this study may not be adequate for estimating FFM in elite youth male soccer players, except the equations of Slaughter et al (1988), Durnin and Wormersley (1974), and Sarria et al (1998). We recommend the use of the new soccer-specific equation proposed in this study as a valid alternative to DXA to quantify FFM among elite youth male players.
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Distribuição da Gordura Corporal/métodos , Distribuição da Gordura Corporal/estatística & dados numéricos , Índice de Massa Corporal , Futebol/fisiologia , Absorciometria de Fóton , Adolescente , Braço/anatomia & histologia , Composição Corporal , Estudos Transversais , Impedância Elétrica , Quadril/anatomia & histologia , Humanos , Perna (Membro)/anatomia & histologia , Masculino , Análise de Regressão , Reprodutibilidade dos Testes , Dobras Cutâneas , Circunferência da CinturaRESUMO
This study determined the most effective field method for quantifying body fat percentage in male elite youth soccer players and developed prediction equations based on anthropometric variables. Forty-four male elite-standard youth soccer players aged 16.3-18.0 years underwent body fat percentage assessments, including bioelectrical impedance analysis and the calculation of various skinfold-based prediction equations. Dual X-ray absorptiometry provided a criterion measure of body fat percentage. Correlation coefficients, bias, limits of agreement, and differences were used as validity measures, and regression analyses were used to develop soccer-specific prediction equations. The equations from Sarria et al. (1998) and Durnin & Rahaman (1967) reached very large correlations and the lowest biases, and they reached neither the practically worthwhile difference nor the substantial difference between methods. The new youth soccer-specific skinfold equation included a combination of triceps and supraspinale skinfolds. None of the practical methods compared in this study are adequate for estimating body fat percentage in male elite youth soccer players, except for the equations from Sarria et al. (1998) and Durnin & Rahaman (1967). The new youth soccer-specific equation calculated in this investigation is the only field method specifically developed and validated in elite male players, and it shows potentially good predictive power.
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Distribuição da Gordura Corporal/métodos , Futebol/fisiologia , Absorciometria de Fóton , Adolescente , Distribuição da Gordura Corporal/estatística & dados numéricos , Estatura , Índice de Massa Corporal , Estudos Transversais , Impedância Elétrica , Humanos , Masculino , Análise de Regressão , Dobras CutâneasRESUMO
This study investigated the effects of successive matches on match-running in elite under-23 soccer players during an international tournament. Match-running data was collected using a semi-automated multi-camera tracking system during an international under-23 tournament from all participating outfield players. Players who played 100% of all group stage matches were included (3 matches separated by 72 h, n = 44). Differences in match-running performance between matches were identified using a generalised linear mixed model. There were no clear effects for total, walking, jogging, running, high-speed running and sprinting distance between matches 1 and 3 (effect size (ES); -0.32 to 0.05). Positional analysis found that sprint distance was largely maintained from matches 1 to 3 across all positions. Attackers had a moderate decrease in total, jogging and running distance between matches 1 and 3 (ES; -0.72 to -0.66). Classifying players as increasers or decreasers in match-running revealed that match-running changes are susceptible to individual differences. Sprint performance appears to be maintained over successive matches regardless of playing position. However, reductions in other match-running categories vary between positions. Changes in match-running over successive matches affect individuals differently; thus, players should be monitored on an individual basis.
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Desempenho Atlético/fisiologia , Comportamento Competitivo/fisiologia , Corrida/fisiologia , Futebol/fisiologia , Humanos , Masculino , Estudos de Tempo e Movimento , Adulto JovemRESUMO
Moalla, W, Fessi, MS, Makni, E, Dellal, A, Filetti, C, Di Salvo, V, and Chamari, K. Association of physical and technical activities with partial match status in a soccer professional team. J Strength Cond Res 32(6): 1708-1714, 2018-The purpose of this study was to examine the association between physical and technical activities and partial match status (winning, drawing, or losing) in a professional soccer team over 2 seasons. Physical and technical activities of 52 official matches were collected and analyzed at each 15-minute interval, for each half (45 minutes), and full match (90 minutes) using a multiple-camera computerized tracking system. The results indicated that according to full match outcome: winning status was characterized by players covering more total distance (p ≤ 0.05) and low-intensity running (<14.4 km·h) (p ≤ 0.05), whereas, losing status induced more sprinting (≥25.2 km·h) (p < 0.01) and high-intensity running (≥19.8 km·h) (p ≤ 0.05). However, according to partial match status (i.e., 15 minutes and half time), players covered more distance for all running intensities while winning (p < 0.01). Technical match performance scores were not influenced by match status. In conclusion, the present study showed that the physical activities including high-intensity running and total distance covered were related to the match status, whereas technical activities were not. The overall outcome shows that higher physical activity was associated with winning partial match periods. This approach highlights the importance of physical fitness in soccer and may help coaches to better modulate players' roles and team tactical organization throughout the match.
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Exercício Físico/fisiologia , Futebol/fisiologia , Humanos , Aptidão Física , Corrida/fisiologia , Estações do AnoRESUMO
This study aimed to examine: (i) the effect of decreasing training load (TL) during taper weeks on physical match activities in professional soccer players, and (ii) to disclose the relationship between weekly TL and physical match activities. Rating of perceived exertion was collected after each training session and match to quantify the TL in 19 professional players over 17 standard and 7 taper weeks during the season. Physical match activities were quantified by a computerised match analysis system and compared between standard training and taper weeks. Compared to standard weeks, the duration and frequency of training sessions during the taper weeks decreased (-21.7% and -18.8%, respectively; P < 0.01) with no change in intensity (-4.8%; P = 0.09). Consequently, the weekly TL decreased during the taper weeks (-25.5%; P < 0.01). Increases in distance covered by intense running (+15.1%; P < 0.05), high-intensity running (HIR) (+15.7%; P < 0.01), number of sprints (+17.8%; P < 0.05) and number of high-speed runs (+15.7%; P < 0.05) were observed during the seven matches played after the taper weeks. High relationships were observed between TL and HIR distance covered, number of HIR and number of sprints (r = -0.53; r = -0.55; r = -0.65, respectively; P < 0.01). Decreasing TL during taper weeks by reducing training duration and frequency but maintaining intensity was associated with an increase in physical activities during matches. However, it needs to be determined whether tapering or other match factors led to the changes in match activity.
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Educação Física e Treinamento/métodos , Resistência Física , Corrida , Futebol , Adulto , Desempenho Atlético , Comportamento Competitivo , Humanos , Masculino , Esforço Físico , Adulto JovemRESUMO
Abstract During the past decade substantial development of computer-aided tracking technology has occurred. Therefore, we aimed to provide calibration equations to allow the interchangeability of different tracking technologies used in soccer. Eighty-two highly trained soccer players (U14-U17) were monitored during training and one match. Player activity was collected simultaneously with a semi-automatic multiple-camera (Prozone), local position measurement (LPM) technology (Inmotio) and two global positioning systems (GPSports and VX). Data were analysed with respect to three different field dimensions (small, <30 m2 to full-pitch, match). Variables provided by the systems were compared, and calibration equations (linear regression models) between each system were calculated for each field dimension. Most metrics differed between the 4 systems with the magnitude of the differences dependant on both pitch size and the variable of interest. Trivial-to-small between-system differences in total distance were noted. However, high-intensity running distance (>14.4 km · h-1) was slightly-to-moderately greater when tracked with Prozone, and accelerations, small-to-very largely greater with LPM. For most of the equations, the typical error of the estimate was of a moderate magnitude. Interchangeability of the different tracking systems is possible with the provided equations, but care is required given their moderate typical error of the estimate.
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OBJECTIVE: To describe components of night-to-night variation in objective measures of sleep. METHODS: We conducted a secondary data analysis of consecutive and chronologically ordered actigraphy-based measurements for time in bed (min), time asleep (min), and wake-after-sleep onset (min). This investigation examined 575 individual night-based measures available for a sub-sample of fifty-two, male youth Middle Eastern football players tracked over a 14-day surveillance period (chronological age range: 12.1 to 16 years). Distinct multivariable-adjusted generalized additive models included each objective sleep outcome measure as dependent variable and disaggregated components of variation for night measurement-by-sleep period interaction, week part (weekday or weekend), and study participant random effects from within-subject night-to-night sleep variation. RESULTS: The within-subject standard deviation (SD) of ±98 min (95% confidence interval [CI], 92 to 104 min) for time in bed, ±87 min (95%CI, 82 to 93 min) for time asleep, and ±23 min (95%CI, 22 to 25 min) for wake-after-sleep-onset overwhelmed other sources of variability and accounted for â¼44% to 53% of the overall night-to-night variation. The night measurement-by-fragmented sleep period interaction SD was ±83 min (95%CI, 44 to 156 min) for time in bed, ±67 min (95%CI, 34 to 131 min) for time asleep, and ±15 min (95%CI, 7 to 32 min) for wake-after-sleep-onset that accounted for â¼22% to 32% of each sleep outcome measure overall variability. CONCLUSIONS: Substantial random night-to-night within-subject variability poses additional challenges for strategies aiming to mitigate problems of insufficient and inconsistent sleep that are detrimental to school learning and youth athlete development processes.
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Distúrbios do Início e da Manutenção do Sono , Futebol , Adolescente , Criança , Humanos , Masculino , Actigrafia , Polissonografia , SonoRESUMO
OBJECTIVE: To examine the abrupt effects of Ramadan onset on actigraphy-based time asleep in male youth Muslim football players. METHODS: We adopted a quasi-experimental, interrupted time-series research design and tracked objective time asleep over a minimum of 12 consecutive nights in the two weeks prior to and immediately after Ramadan onset, respectively. Twenty-two, male academy student-athletes (chronological age range: 12.6 to 16.2 years) participated in the study (464 individual observations). Segmented generalized mixed-effects modelling estimated the effects of Ramadan onset on time asleep during the first period of night sleep only. RESULTS: Ramadan onset led to an immediate mean reduction of 89 min (95% confidence interval [CI], 54 to 123 min) in time asleep during the first period of night sleep compared to pre-Ramadan sleep patterns. Model-adjusted estimated marginal means for time asleep were ~ 5.7 h (95%CI, 5.1 to 6.2 h) before and ~ 4.2 h (95%CI, 3.6 to 4.7 h) after Ramadan onset. Night sleep interruptions resulting in two or more fragmented periods accounted for 8% (95%CI, 2 to 21%) to 19% (95%, 11 to 29%) of sleep observations before and after Ramadan onset, respectively. CONCLUSIONS: The onset of Ramadan determined an abrupt reduction in time asleep of ~ 1 h 30 min in the first period of a night cycle and contributed to additional problems of heterogeneous sleep fragmentation that can impact optimal school learning and youth athlete performance development processes.
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The use of data and analytics in professional football organisations has grown steadily over the last decade. Nevertheless, how and whether these advances in sports analytics address the needs of professional football remain unexplored. Practitioners from national federations qualified for the FIFA World Cup Qatar 2022™ and professional football clubs from an international community of practitioners took part in a survey exploring the characteristics of their data analytics infrastructure, their role, and their value for elaborating player monitoring and positional data. Respondents from 29 national federations and 32 professional clubs completed the survey, with response rates of 90.6% and 77.1%, respectively. Summary information highlighted the underemployment of staff with expertise in applied data analytics across organisations. Perceptions regarding analytical capabilities and data governance framework were heterogenous, particularly in the case of national federations. Only a third of national federation respondents (~30%) perceived information on positional data from international sports data analytics providers to be sufficiently clear. The general resourcing limitations, the overall lack of expertise in data analytics methods, and the absence of operational taxonomies for reference performance metrics pose constraints to meaningful knowledge translations from raw data in professional football organisations.
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Rapid somatic growth and biological maturity status may affect injury patterns in youth football, yet firm conclusions cannot be drawn from the existing research. We aimed to explore growth velocity, maturity, and age as injury risk factors in 95 academy players (11.9-15.0 years), using anthropometric (height and body mass), maturity (skeletal age), injury, and football exposure data collected prospectively over three seasons (2016/17-2018/19). We compared the relative quality of mixed-effects logistic regression models with growth velocity for 223 growth intervals (average 113 days) included as fixed effects and adjusted for age (chronological or skeletal) plus load (hours/week). Associations were considered practically relevant based on the confidence interval for odds ratios, using thresholds of 0.90 and 1.11 to define small beneficial and harmful effects, respectively. We observed harmful effects of older age on overall (OR: 2.61, 95% CI: 1.15-5.91) and sudden onset (1.98, 1.17-3.37) injury risk. Significant associations (p<0.05) were observed for higher body mass change and greater maturity on sudden onset injuries, and for higher hours/week on gradual onset, bone tissue, and physis injuries. Future studies should include larger samples, monitoring athletes from pre-adolescence through maturation, to enable within-subject analyses and better understand the relationship between growth, maturation, and injuries.
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PURPOSE: To develop age-specific reference intervals for physical performance test outcomes relevant to male youth Middle Eastern football players. METHODS: We analyzed mixed-longitudinal data (observations range: 1751-1943 assessments) from a sample of 441 male youth outfield football players (chronological age range: 11.7-18.4 y) as part of the Qatar Football Association and Aspire Academy development program over 14 competitive seasons. Semiparametric generalized additive models for location, scale, and shape estimated age-specific reference centiles for 10-m sprinting, 40-m sprinting, countermovement jump height, and maximal aerobic speed variables. RESULTS: The estimated reference intervals indicated that the distribution of the physical performance test scores increased monotonically and nonlinearly with advancing chronological age for sprinting and countermovement jump outcome measures, reaching a plateau after 16 years common to each of these performance variables. The maximal aerobic speed median score increased substantially until â¼14.5 years, with the nonlinear trend flattening off toward relatively older chronological ages. CONCLUSIONS: We developed age-related reference intervals for physical performance test outcomes relevant to youth Qatari football players. Country-wide age-specific reference intervals can assist in the longitudinal tracking of the individual players' progress over time against benchmark values derived from the reference population.
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Desempenho Atlético , Futebol Americano , Humanos , Masculino , Adolescente , Criança , Estações do Ano , Desempenho Físico FuncionalRESUMO
PURPOSE: To examine the general perspectives of elite soccer players on the time course of perceived postmatch fatigue and the influence of away matches on subjective perceptions. METHODS: Adopting a cross-sectional study design, we invited 371 subjects from 14 top-division European clubs competing in the Belgian First Division A, English Premier League, French Ligue 1, Italian Serie A, Portuguese Primeira Liga, Russian Premier League, and Swiss Premier League to take part in a short survey on general issues relating to postmatch fatigue measurement and tracking in professional soccer. RESULTS: Three hundred male professional soccer players completed the short questionnaire. For perceptions relevant to the time course of postmatch fatigue, two-thirds of respondents (67%) indicated higher postmatch fatigue perceived 2 days (48 h) after an official competition. Among these respondents, a higher proportion of answers was observed in wide midfielders (74%), attackers (74%), and central midfielders (68%). Approximately two-thirds of respondents (63%) indicated more than usual and much more than usual perceived postmatch fatigue following away matches. CONCLUSIONS: For the first time, our investigation addressed practical aspects that remained unexplored and fundamental to the definition of an optimal player management process following a competition. From a practical standpoint, perspectives of individual elite soccer players substantiated the notion of implementing processes with dedicated recovery protocols within 48 hours postmatch and highlighted the need for differential strategies addressing the additional burden of away matches and travel.