An injury audit in high-level male youth soccer players from English, Spanish, Uruguayan and Brazilian academies

The Impact of Injury on Career Progression in Elite Youth Football-Findings at 10 Years

Background: There is a lack of evidence regarding the impact of time loss, match exposure, and age at injury on career progression in elite football. Therefore, the aim of this study was to identify injury characteristics and their influence on career progression in a German youth academy. Methods: During the 2012/2013 season, a prospective cohort study reported 107 time-loss injuries among 130 young athletes from an elite German soccer academy. Individual career progression was analyzed using 10-year data. Results: Injuries and time loss were not associated with career progression (p > 0.05) in the overall cohort. In the U17 and U19 groups, 24% were able to reach the professional level, with injuries significantly decreasing this probability (p = 0.002). Injuries lasting more than 28 days had a negative impact on career progression compared to minor injuries (30% vs. 10%; p = 0.02). Conclusions: Not only the characteristics of injuries, but also their impact on career development, vary with age. In the U17 and U19 age groups, serious injuries resulting in more than 28 days of absence have a negative impact on career progression. It is important to be aware of these effects in order to focus on the prevention of long-term injuries to ensure the optimal development of young athletes.

Exploring the true burden of a time-loss injury: full vs partial time-loss in elite academy football (soccer)

In football, the number of days without full participation in training/competition is often used as a surrogate measure for time-loss (TL) caused by injury. However, injury management and return-to-play processes frequently include modified participation, which to date has only been recorded through self-reports. This study aims to demonstrate the differentiation between 'full' (no participation in team football) and 'partial' (reduced/modified participation in team football) burden. Injury and exposure data were collected from 118 male elite footballers (U13-U18) over 3 consecutive seasons according to the Football Consensus Statement. TL injury burden was calculated separately as the number of total, 'full' and 'partial' days lost per 1000 h of exposure. Injury burden (137.2 days lost/1000 h, 95% CI 133.4-141.0) was comprised of 23% (31.9 days lost/1000 h, 95% CI 30.1-33.8) partial TL and 77% (105.3 days lost/1000 h, 95% CI 102.0-108.6) full TL burden. Injuries of moderate severity (8-28 days lost) showed 40% of partial TL. TL injury incidence rate (6.6 injuries/1000 h, 95% CI 5.8-7.5), the number of severe injuries (16%), and the distribution of TL and non-TL injuries (56% and 44%) were comparable to other reports in elite youth footballers. Almost one-quarter of the TL injury burden showed that injured players were still included in some team football activities, which, for injuries with TL >7 days, was likely related to the return to play process. Therefore, reporting on partial TL provides insight into the true impact of injury on participation levels.

Exploring Growth, Maturity, and Age as Injury Risk Factors in High-Level Youth Football

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.

The Genetic Association with Athlete Status, Physical Performance, and Injury Risk in Soccer

The aim of this review was to critically appraise the literature concerning the genetic association with athlete status, physical performance, and injury risk in soccer. The objectives were to provide guidance on which genetic markers could potentially be used as part of future practice in soccer and to provide direction for future research in this area. The most compelling evidence identified six genetic polymorphisms to be associated with soccer athlete status (ACE I/D; ACTN3 rs1815739; AGT rs699; MCT1 rs1049434; NOS3 rs2070744; PPARA rs4253778), six with physical performance (ACTN3 rs1815739; AMPD1 rs17602729; BDNF rs6265; COL2A1 rs2070739; COL5A1 rs12722; NOS3 rs2070744), and seven with injury risk (ACTN3 rs1815739; CCL2 rs2857656; COL1A1 rs1800012; COL5A1 rs12722; EMILIN1 rs2289360; IL6 rs1800795; MMP3 rs679620). As well as replication by independent groups, large-scale genome-wide association studies are required to identify new genetic markers. Future research should also investigate the physiological mechanisms associating these polymorphisms with specific phenotypes. Further, researchers should investigate the above associations in female and non-Caucasian soccer players, as almost all published studies have recruited male participants of European ancestry. Only after robust, independently replicated genetic data have been generated, can genetic testing be considered an additional tool to potentially inform future practice in soccer.

How Does Age Affect Injury Characteristics in Young Elite Footballers?-A Prospective Cohort Study of a German Youth Academy

BACKGROUND

Little is known about age-related changes in injury characteristics and burden, and existing data are inconsistent, highlighting the need for new studies on this topic. This study aimed to describe age-related injury risk, severity and burden in a German elite youth football academy.

METHODS

A prospective cohort study was conducted in the 2012/2013 season, reporting 109 time-loss injuries among 138 young athletes playing at an elite football academy in Germany. For the most severe injuries, the injury burden in the different age groups was considered separately.

RESULTS

Athletes missed a total of 2536 days of exposure, resulting in an overall incidence of 2.6 per 1000 h (1.7-3.0; 95% CI) and a burden of 60.6 days lost per 1000 h (40.8-80.3; 95% CI). The incidence and burden of joint sprains and muscle injuries were higher in the older age groups. Physeal injuries peaked in the U14 age group during the pubertal growth spurt. Bone injuries and contusions showed no age trend.

CONCLUSION

Injury characteristics vary with age. The overall incidence, severity and burden of injuries increased with the age of the athletes. To ensure the optimal development of young athletes, it is important to be aware of the differences in injury susceptibility between age groups in order to implement tailored prevention programmes.

Injury Patterns and Incidence in an Elite Youth Football Academy-A Prospective Cohort Study of 138 Male Athletes

BACKGROUND

There is a lack of evidence regarding injury incidence in German elite youth football academies, and the risk of re-injury is unknown. Therefore, the objectives of this study were (1) to determine injury patterns and incidence in an elite youth football academy in Germany, (2) to monitor overuse-/trauma-related injuries over the course of the season, and (3) determine the risk of re-injury.

METHODS

A prospective cohort study was conducted in the 2012/2013 season among 138 male players from an elite youth football academy in Germany. Injuries were recorded according to the consensus statement on injury definitions and data collection in studies of football injuries. Injury incidence was reported as the number of injuries per 1000 h of exposure and the number of injuries per squad season.

RESULTS

A total of 109 injuries were reported, resulting in a cumulative time-loss of 2536 days. A squad of 25 players sustained 19.7 injuries per season, with an average of 23.3 days (15.7-30.9; 95% CI lower-upper) of absence per injury. Ligament sprains (28%), muscle strains (19%) and physeal injuries (12%) were the most common causes of time-loss. Physeal injuries were the most common severe type of injury (29%), with a mean time-loss of 29.7 days (18.2-41.2; 95% CI lower-upper). Re-injuries accounted for 3% of all injuries and resulted in significantly more time-loss than non-re-injuries (60 vs. 23 days; p = 0.01).

CONCLUSION

In the youth academies studied, a team of 25 players sustained an average of 19.7 injuries per season, resulting in a cumulative time-loss of 459 days. Physeal injuries are a major contributor to severe injuries and therefore require special attention.

Daily energy requirements of male academy soccer players are greater than age-matched non-academy soccer players: A doubly labelled water investigation

This study aimed to test the hypothesis that the total daily energy expenditure (TDEE) of male academy soccer players is greater than players not enrolled on a formalised academy programme. English Premier League academy (ACAD: n = 8, 13 years, 50 ± 6 kg, 88 ± 3% predicted adult stature, PAS) and non-academy players (NON-ACAD: n = 6, 13 years, 53 ± 12 kg, 89 ± 3% PAS) were assessed for TDEE (via doubly labelled water) during a 14-day in-season period. External loading was evaluated during training (ACAD: 8 sessions, NON-ACAD: 2 sessions) and games (2 games for both ACAD and NON-ACAD) via GPS, and daily physical activity was evaluated using triaxial accelerometry. Accumulative duration of soccer activity (ACAD: 975 ± 23 min, NON-ACAD: 397 ± 2 min; p < 0.01), distance covered (ACAD: 54.2 ± 8.3 km, NON-ACAD: 21.6 ± 4.7 km; p < 0.05) and time engaged in daily moderate-to-vigorous (ACAD: 124 ± 17 min, NON-ACAD: 79 ± 18 min; p < 0.01) activity was greater in academy players. Academy players displayed greater absolute (ACAD: 3380 ± 517 kcal · d-1, NON-ACAD: 2641 ± 308 kcal · d-1; p < 0.05) and relative TDEE (ACAD: 66 ± 6 kcal · kg · d-1, NON-ACAD: 52 ± 10 kcal · kg · d-1; p < 0.05) versus non-academy players. Given the injury risk associated with high training volumes during growth and maturation, data demonstrate the requirement for academy players to consume sufficient energy (and carbohydrate) intake to support the enhanced energy cost of academy programmes.

Can we reduce injury risk during the adolescent growth spurt? An iterative sequence of prevention in male academy footballers

Background: The adolescent growth spurt is associated with an increased risk of injury in young athletes.Aim: This study aimed to use an interdisciplinary collaboration between technical coaches, sports scientists, and medical staff to mitigate this risk.Subjects and methods: 77 male academy footballers were followed across two seasons. At-risk players were identified using somatic maturity status and growth rate in stature and the lower limbs, using thresholds of 88% to 92.8% of predicted adult stature, ≥7.2 cm/year, and ≥3.6 cm/year, respectively. During the 2019-20 season, players with symptoms of a growth-related injury or two of three risk factors were included in an intervention strategy that included modified training load, football-specific skills, balance, coordination and landing drills, and an individualised strength program.Results: For players with the three risk factors, there was a significant reduction in the incidence (rate ratio [RR] = 0.14 (5.2 per 1000h → 0.8 per 1000h, p = 0.05) and burden (RR = 0.08 (216 per 1000h → 17 per 1000h, p = 0.02) between the seasons. For players with ≤2 risk factors, there were no significant differences in injury risk between the baseline and intervention seasons.Conclusion: Overall, it may be possible to mitigate injury incidence and burden during the adolescent growth spurt in high-risk athletes.

The incidence and burden of injuries in elite English youth female soccer players

This study aimed to investigate the incidence, severity and burden of injury in English elite youth female soccer players. Qualified therapists at six English girls' academies prospectively recorded all injuries that required medical attention or caused time loss for matches and training in 375 elite youth female soccer players (under-10 [U10], U12, U14 and U16) during the 2019/2020 season. One hundred- and eleven time-loss injuries (52 from training, 59 from matches) were sustained, resulting in 1,946 days absent (779 days from training injuries, 1,167 days from match injuries) from soccer activities. The injury incidence for matches (9.3/1000 hours, 95% CIs: 7.2-11.9) was significantly greater than training (1.1/1000 hours, 95% CIs: 0.9-1.5, p < 0.001). Additionally, the injury burden for matches (183 days lost/1000 hours, 95% CIs: 142-237) was significantly greater than training (17 days lost/1000 hours, 95% CIs: 13-22, p < 0.001). Injury incidence and burden were greatest in the U16 age group and were found to increase with age. Whilst injury incidence and burden are greater in matches than training, a large proportion of preventable injuries, soft-tissue and non-contact in nature, were sustained in training. Findings provide comparative data for elite youth female soccer players.

The Effect of Spinal Asymmetries on Physical Fitness Parameters in Young Elite Soccer Players

The purpose of the study was to examine the effect of spinal asymmetries on specific physical fitness parameters in young elite soccer players. Fifty male soccer players, all members of the under 17 (U17) and 15 (U15) National teams of Cyprus, were initially evaluated for thoracic kyphosis, lumbar lordosis and scoliosis asymmetries. Based on the spinal asymmetries’ initial evaluation, soccer players were categorized into the asymmetry group (AG) and normal group (NG) per spinal asymmetry. Hamstring and lower-back flexibility, countermovement jump (CMJ) and lower body isokinetic maximum force were evaluated between AG and NG. CMJ with arm swing was lower in kyphotic posture AG compared with the NG (AG: 41.70 ± 3.59 cm, NG: 44.40 ± 4.34 cm; p = 0.028). Single leg CMJ was lower in both legs in scoliotic posture AG compared with the NG (right: AG: 17.42 ± 1.86 cm, NG: 19.16 ± 2.42 cm, p = 0.008, left: AG: 17.54 ± 1.33 cm, NG: 19.97 ± 2.91 cm; p = 0.002). Sit-and-reach flexibility was lower in scoliotic posture AG (AG: 20.44 ± 5.76 cm, NG: 24.82 ± 6.83 cm; p = 0.024) and higher in lordotic posture AG (AG: 25.95 ± 6.59 cm, NG: 21.73 ± 6.45 cm; p = 0.04) both compared with the NG. No significant difference was found for quadriceps and hamstrings concentric peak torque between the AG and NG (p > 0.05). The current study revealed that kyphotic and scoliotic posture asymmetries deteriorate neuromuscular explosiveness performance and diminish lower limbs’ flexibility in young International-level soccer players.

Growth, maturation and injuries in high-level youth football (soccer): A mini review

Understanding the challenges football (soccer) players face during adolescence is fundamental to avoid disruptions in their development due to injury. This mini review will describe basic concepts of somatic growth and biological maturity, examine data from 53 prospective epidemiological studies on high-level youth football players and discuss how age, growth and maturity may affect the injury patterns observed. Based on the existing evidence, at least every third player sustains an injury during a football season. The thigh (median for studies of boys: 25%, median for girls: 21%), ankle (b: 18%, g: 30%), knee (b: 17%, g: 18%) and hip/groin (b: 14%, g: 10%) are the body parts injured most often, while muscle strains (b: 31%, g: 25%), sprains (b: 20%, g: 27%) and contusions (b: 17%, g: 16%) are the most common injury types. Injury trends are, however, not consistent throughout adolescence, and players' age, maturity status and position relative to peak height velocity (PHV) have shown to influence the number, type and location of injuries sustained. Despite a high volume of observational injury studies published on high-level youth players, girls (7 studies) and settings outside of Europe (included in 23% of studies) are underrepresented and should receive extra attention in the future. Based on the available epidemiological data, tailored injury reduction programmes can be considered in youth football, alongside application of general training principles such as progression, variation and individualization which may be especially important during vulnerable phases such as the adolescent growth spurt.

Elit genç futbol akademisi sporcularında yaralanma insidansı: 3 yıllık geriye dönük takip

Aim: The aim of this study was to investigate the incidence and characteristics of injuries suffered by elite soccer academy athletes. Materials and Methods: A retrospective analysis was made of the health records between 2016 and 2019 of athletes in the elite male soccer academy of an elite football club. The cause, type, location, recurrence, and severity of the injuries, where the injuries occured and time lost due to the injuries were recorded. The injury incidence and prevalence were calculated. Results: Overall, total injuries and seasonal incidence rate were 1.49 (1.33-1.68) and 8.06 (7.16-0.04) per 1000 hours, respectively. The injury burden ranged between 11.83 (10.53-13.29) days and 51.43 (49.11-53.85) days. The injury characteristics were not statistically different according to age groups (p˃0.05). Conclusion: Youth soccer players in the U19 and U21 age groups had more injuries than other junior age groups in a typical soccer season. It was concluded that there were more match injuries, the thigh was the most injured area, muscle injuries were more common, and the hamstring was the most frequently injured muscle.

Playing Position is Associated with Injury Incidence Rate in Male Academy Soccer Players

CONTEXT

It is unclear whether playing position influences injury in male academy soccer players (ASP).

OBJECTIVE

To determine if playing position is associated with injury in ASP.

DESIGN

Descriptive Epidemiology Study.

SETTING

English, Spanish, Uruguayan and Brazilian soccer academies.

PARTICIPANTS

369 ASP from Under 14 (U14) to U23 age groups, classified as 'post-peak height velocity' using maturity offset, and grouped as goalkeepers (GK), lateral defenders (LD), central defenders (CD), lateral midfielders (LM), central midfielders (CM) and forwards (FWD). Additional analysis compared central (CENT) with lateral/forward (LAT/FWD) positions.

MAIN OUTCOME MEASURES

Injuries were recorded prospectively over one season. Injury prevalence proportion (IPP), days missed and injury incidence rate (IIR, injuries per 1000 training/match hours, n=116) were analysed according to playing position.

RESULTS

No association with playing position was observed for any injury type/location regarding IPP (P≥0.089) or days missed (P≥0.235). The IIR was higher in CD than LD for general (9.30 vs. 4.18 injuries/1000h, P=0.009), soft-tissue (5.14 vs. 1.95 injuries/1000h, P=0.026) and ligament/tendon injuries (2.69 vs. 0.56 injuries/1000h, P=0.040). Regarding CENT vs. LAT/FWD, there were no associations with IPP (P≥0.051) or days missed (P≥0.083), but general IIR was greater in CENT than LAT/FWD (8.67 vs. 6.12 injuries/1000h, P=0.047).

CONCLUSIONS

ASP playing position was not associated with IPP or days missed but the higher general, soft-tissue and ligament/tendon IIR in CD suggests this position warrants specific attention regarding injury prevention strategies. These novel findings highlight the importance of including training/match exposure when investigating the influence of playing position on injury in ASP.

Training Management of the Elite Adolescent Soccer Player throughout Maturation

Professional soccer clubs invest significantly into the development of their academy prospects with the hopes of producing elite players. Talented youngsters in elite development systems are exposed to high amounts of sports-specific practise with the aims of developing the foundational skills underpinning the capabilities needed to excel in the game. Yet large disparities in maturation status, growth-related issues, and highly-specialised sport practise predisposes these elite youth soccer players to an increased injury risk. However, practitioners may scaffold a performance monitoring and injury surveillance framework over an academy to facilitate data-informed training decisions that may not only mitigate this inherent injury risk, but also enhance athletic performance. Constant communication between members of the multi-disciplinary team enables context to build around an individual's training status and risk profile, and ensures that a progressive, varied, and bespoke training programme is provided at all stages of development to maximise athletic potential.

The genetic association with injury risk in male academy soccer players depends on maturity status

It is currently unknown if injury risk is associated with genetic variation in academy soccer players (ASP). We investigated whether nine candidate single nucleotide polymorphisms were associated (individually and in combination) with injury in ASP at different stages of maturation. Saliva samples and one season's injury records were collected from 402 Caucasian male ASP from England, Spain, Uruguay, and Brazil, whose maturity status was defined as pre- or post-peak height velocity (PHV). Pre-PHV COL5A1 rs12722 CC homozygotes had relatively higher prevalence of any musculoskeletal soft tissue (22.4% vs. 3.0%, p = 0.018) and ligament (18.8% vs. 11.8%, p = 0.029) injury than T-allele carriers, while VEGFA rs2010963 CC homozygotes had greater risk of ligament/tendon injury than G-allele carriers. Post-PHV IL6 rs1800795 CC homozygotes had a relatively higher prevalence of any (67.6% vs. 40.6%, p = 0.003) and muscle (38.2% vs. 19.2%, p = 0.013) injuries than G-allele carriers. Relatively more post-PHV EMILIN1 rs2289360 CC homozygotes suffered any injury than CT and TT genotypes (56.4% vs. 40.3% and 32.8%, p = 0.007), while the "protective" EMILIN1 TT genotype was more frequent in post- than pre-PHV ASP (22.3 vs. 10.0%, p = 0.008). Regardless of maturity status, T-alleles of ACTN3 rs1815739 and EMILIN1 rs2289360 were associated with greater absence following ankle injury, while the MMP3 rs679620 T-allele and MYLK rs28497577 GT genotype were associated with greater absence following knee injury. The combination of injury-associated genotypes was greater in injured vs. non-injured ASP. This study is the first to demonstrate that a genetic association exists with injury prevalence in ASP, which differs according to maturity status.

Shedding light on incidence and burden of physeal injuries in a youth elite football academy: A 4-season prospective study

INTRODUCTION

Physeal injuries have been overlooked in epidemiological research in youth sports. Our prospective study investigated the incidence, severity, and burden of physeal injuries in a youth elite football academy.

METHODS

In total, 551 youth male football players from under-9 to under-19 were included and observed over four consecutive seasons. Injuries involving the physis were diagnosed and recorded according to type, location, and diagnosis. Injury incidence (II), severity (days lost), and injury burden (IB) were calculated per squad per season (25 players/squad).

RESULTS

There were 307 physeal injuries: 262 apophyseal (85%), 26 physeal (9%), 2 epiphyseal (1%), and 17 other physeal injuries (5%) with 80% (n=245) causing time-loss. The overall mean incidence of time-loss physeal injuries was 6 injuries/squad-season, leading to a total of 157 days lost/squad-season. The U-16s had the highest burden with 444 days lost per squad-season [median: 20 (95% CI: 12-30) days; II: 10 (95% CI: 7.3.1-13.4)]. Apophyseal injuries of the hip-pelvis resulted in the greatest burden [median: 13 (95% CI: 10-17); II: 2.5 (95% CI: 2.1-3.0)]. Peak apophyseal injury incidence per body parts occurred in U-11 for foot-ankle (II: 2.4; 95% CI: 1.0-4.9), U-14 for knee (II: 4.5; 95% CI: 2.7-7.1), and U-17 for hip-pelvis (II: 6.4; 95% CI: 4.2-9.3).

CONCLUSION

Physeal injuries accounted for a quarter of all-time loss with the largest injury burden in U-16. Most physeal injuries involved the lower limb and affected the apophysis. Physeal and apophyseal injuries incidence, burden, and pattern vary substantially depending on age. Hip-pelvic apophyseal injuries accounted for the largest injury burden.

Injury patterns differ with age in male youth football: a four-season prospective study of 1111 time-loss injuries in an elite national academy

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.

M. Biceps Femoris Long Head Architecture and Sprint Ability in Youth Soccer Players

PURPOSE

Hamstring muscle architecture may be associated with sprint performance and the risk of sustaining a muscle injury, both of which increase during puberty. In this study, we investigated the m. biceps femoris long head (BFlh) cross-sectional area (ACSA), fascicle length (FL) and pennation angle (PA), and sprint performance as well as their relationship in under 13 to 15 youth soccer players.

METHODS

We measured 85 players in under-13 (n = 29, age = 12.5 [0.1] y, height = 155.3 [6.2] cm, weight = 43.9 [7.6] kg), under-14 (n = 25, age = 13.5 [0.3] y, height = 160.6 [7.7] cm, weight = 47.0 [6.8] kg), and under-15 (n = 31, age = 14.4 [0.3] y, height = 170.0 [7.7] cm, weight = 58.1 [8.8] kg) teams. We used ultrasound to measure BFlh ACSA, FL and PA, and sprint tests to assess 10- and 30-m sprint time, maximal velocity  (vmax), and maximal acceleration (αmax). We calculated Pearson r to assess the relationship between sprint ability and architectural parameters.

RESULTS

All muscle architectural parameters increased from the under-13 to the under-15 age group (BFlh ACSA = 37%, BFlh FL = 11%, BFlh PA = 8%). All sprint performance parameters improved from the under-13 to under-15 age categories (30-m time = 7%, 10-m time = 4%, vmax = 9%, αmax = 7%). The BFlh ACSA was correlated with 30-m sprint time (r = -.61 (95% compatibility interval [CI] [-.73, -.45]) and vmax (r = .61, 95% CI [.45, .72]). A combination of BFlh ACSA and age best predicted 30-m time (R² = .47 [.33, .62]) and 10-m time (R² = .23 [.08, .38]).

CONCLUSIONS

Muscle architectural as well as sprint performance parameters increase from the under-13 to under-15 age groups. Even though we found correlations for all assessed architectural parameters, BFlh ACSA was best related to the assessed sprint parameters.

Influence of Size and Maturity on Injury in Young Elite Soccer Players

The involvement of pre-adolescents in soccer is becoming more and more frequent, and this growing participation generates some concerns about the potential factors for sports injuries. The purpose of this study was to investigate sports injuries in younger (U9–U11) and older (U12–U13) children playing soccer at an elite level, analyzing potential anthropometric and maturity risk factors. A total of 88 elite soccer players aged 9–13 years were investigated. Weight, stature, and sitting height were measured at the start and at the end of the competitive season, computing the relative growth velocities. Additional body composition parameters were taken during a second survey. Maturity offset was calculated using predictive equations based on anthropometric traits such as years from age at peak height velocity (YPHV). Injuries suffered during the competitive season were recorded. Maturity and some anthropometric characteristics were significantly different according to the presence or absence of injuries among the players. Multiple logistic regression revealed that YPHV, body mass index (BMI), and calf muscle area were the factors most significantly correlated with injuries. Players with increased BMI, with decreased calf muscle area, and who were closer to their peak height velocity, were at a higher risk of injury. Findings showed that a monitoring program of anthropometric characteristics taking into account the maturational stage needs to be developed to prevent injuries.

Association of Skeletal Maturity and Injury Risk in Elite Youth Soccer Players: A 4-Season Prospective Study With Survival Analysis

BACKGROUND

The association between injury risk and skeletal maturity in youth soccer has received little attention.

PURPOSE

To prospectively investigate injury patterns and incidence in relation to skeletal maturity in elite youth academy soccer players and to determine the injury risks associated with the skeletal maturity status, both overall and to the lower limb apophysis.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

All injuries that required medical attention and led to time loss were recorded prospectively during 4 consecutive seasons in 283 unique soccer players from U-13 (12 years of age) to U-19 (18 years). The skeletal age (SA) was assessed in 454 player-seasons using the Fels method, and skeletal maturity status (SA minus chronological age) was classified as follows: late, SA >1 year behind chronological age; normal, SA ±1 year of chronological age; early, SA >1 year ahead of chronological age; and mature, SA = 18 years. An adjusted Cox regression model was used to analyze the injury risk.

RESULTS

A total of 1565 injuries were recorded; 60% were time-loss injuries, resulting in 17,772 days lost. Adjusted injury-free survival analysis showed a significantly greater hazard ratio (HR) for different status of skeletal maturity: early vs normal (HR = 1.26 [95% CI, 1.11-1.42]; P < .001) and early vs mature (HR = 1.35 [95% CI, 1.17-1.56]; P < .001). Players who were skeletally mature at the wrist had a substantially decreased risk of lower extremity apophyseal injuries (by 45%-61%) compared with late (P < .05), normal (P < .05), and early (P < .001) maturers.

CONCLUSION

Musculoskeletal injury patterns and injury risks varied depending on the players' skeletal maturity status. Early maturers had the greatest overall adjusted injury risk. Players who were already skeletally mature at the wrist had the lowest risk of lower extremity apophyseal injuries but were still vulnerable for hip and pelvis apophyseal injuries.

Strength development and non-contact lower limb injury in academy footballers across age groups

Non-contact lower limb injuries are common in academy football. Yet, the impact these injuries have on strength development in academy footballers remains unclear. This study aimed to investigate the impact of non-contact lower limb injury on hip, groin, and knee flexor strength development in male academy youth footballers. Furthermore, this study: reports normative strength data of emerging field-based tests that can be easily deployed in football academies; explores the effect of age on injury occurrence; and highlights the number of days lost from injury in male youth footballers. Assessments of hip adductor, abductor, and eccentric knee flexor strength were obtained from 195 academy football players during pre-season and at the end of season. In-season injuries were recorded by medical staff. Those footballers who sustained non-contact lower limb injury were compared with those who did not sustain a non-contact lower limb injury. No between-group differences were observed for any strength assessments when controlled for pre-season measures. Stronger footballers at pre-season experienced strength loses, while those weaker players gained strength across the season. Hip strength development was impaired in older age group footballers. Sustaining a non-contact lower limb injury had minimal impact on strength development. In the absence of in-season lower limb strength monitoring, development in academy youth footballers may not progress as expected, and in particular, stronger and older youth athletes may benefit from individualized strength training.

Injury incidence and burden in a youth elite football academy: a four-season prospective study of 551 players aged from under 9 to under 19 years

OBJECTIVE

Investigate the incidence and burden of injuries by age group in youth football (soccer) academy players during four consecutive seasons.

METHODS

All injuries that caused time-loss or required medical attention (as per consensus definitions) were prospectively recorded in 551 youth football players from under 9 years to under 19 years. Injury incidence (II) and burden (IB) were calculated as number of injuries per squad season (s-s), as well as for type, location and age groups.

RESULTS

A total of 2204 injuries were recorded. 40% (n=882) required medical attention and 60% (n=1322) caused time-loss. The total time-loss was 25 034 days. A squad of 25 players sustained an average of 30 time-loss injuries (TLI) per s-s with an IB of 574 days lost per s-s. Compared with the other age groups, U-16 players had the highest TLI incidence per s-s (95% CI lower-upper): II= 59 (52 to 67); IB=992 days; (963 to 1022) and U-18 players had the greatest burden per s-s: II= 42.1 (36.1 to 49.1); IB= 1408 days (1373 to 1444). Across the cohort of players, contusions (II=7.7/s-s), sprains (II=4.9/s-s) and growth-related injuries (II=4.3/s-s) were the most common TLI. Meniscus/cartilage injuries had the greatest injury severity (95% CI lower-upper): II= 0.4 (0.3 to 0.7), IB= 73 days (22 to 181). The burden (95% CI lower-upper) of physeal fractures (II= 0.8; 0.6 to 1.2; IB= 58 days; 33 to 78) was double than non-physeal fractures.

SUMMARY

At this youth football academy, each squad of 25 players averaged 30 injuries per season which resulted in 574 days lost. The highest incidence of TLI occurred in under-16 players, while the highest IB occurred in under-18 players.