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

Injuries in elite male youth football and athletics: Growth and maturation as potential risk factors

Background: Elite youth athletes participate in intense and structured training programmes to realise their performance potential, but their development may be interrupted by injuries. To reduce the impact of injuries we first need to know which injuries affect participation the most and what the risk factors are. Growth and maturation represent two potential non-modifiable intrinsic risk factors that are unique to adolescent athletes. The literature published on this topic is, however, considered of low quality and findings in earlier studies are inconsistent. The aim of this thesis was therefore to identify the most common and burdensome injuries in elite male youth athletes participating in football (soccer) and athletics (track and field) and to explore growth and maturation as risk factors. Methods: All studies were based on data from routine monitoring of athletes at Aspire Academy, a national elite sports academy in Doha, Qatar. Participants were males aged 11 to 18 years participating in the football or athletics programmes. The first study (Paper I) was a methodological study where we investigated the effect on injury incidence when a broad medical-attention definition was used and recorders/supervisors were invested in research projects relying on the data. This study was based on injury data for the U16 through U18 squads from 2012/13 through 2016/17 (211 players). Papers II and III were descriptive epidemiological studies in athletics and football, respectively. Time-loss injuries were collected prospectively over five seasons in athletics (2014/15 through 2018/19, 179 athletes) and four seasons in football (2016/17 through 2019/20, 301 players) by physiotherapists. The most common (injury incidence) and burdensome (injury burden) combinations of injury location and type were identified, and injury patterns were examined for event groups (athletics; non-specialised, endurance, sprints, jumps, throws) and age groups (football; U13 through U18). In Papers IV and V, subsamples of athletes (74 in athletics, 103 in football) from the epidemiological studies with complete growth (anthropometric measures, i.e. height, leg length and body mass) and maturity (skeletal age, using the Fels method) assessments were included. Growth rates, maturity status and maturity tempo were then examined as risk factors for specific injury types. Main results: The level of investment in the injury surveillance programme by the injury recorder (team physiotherapist) or supervisor had a large impact on the incidence of non-time-loss injuries and injuries with a minimal day loss (1-3 days), while time-loss injuries overall were unaffected (Paper I). In athletics (Paper II), the main concerns were bone and muscle injuries, with thigh muscle strains/ruptures, lumbar spine stress fractures and lower leg bone stress injuries as the most burdensome location-type combinations. Injury patterns were, however, specific to each event group. In football (Paper III), typical “football injuries” (knee sprains, thigh strains and ankle sprains) were the most burdensome, followed by lumbosacral bone stress injuries and physis injuries to the hip/groin. Older athletes sustained more injuries relative to exposure (hours); muscle injuries were increasingly common and physis injuries less common with age. In Paper IV, younger skeletal age and greater changes in height, leg length and skeletal age over a season were associated with a greater incidence of bone and growth plate injuries in athletics. No associations with injury risk were found for changes in body mass, trunk height or body mass index. In football (Paper V), growth rates over shorter periods were not related to injury risk when accounting for age (chronological age or skeletal age) and load (weekly exposure). Older skeletal age was associated with significantly greater overall, sudden onset, muscle and joint sprain injury risk. The associations could, however, not be considered practically relevant due to the uncertain estimates for the odds ratios. Conclusion: Based on our findings, time-loss incidence should be used when multiple medical staff recorders are involved in the data collection. Injuries patterns in elite male youth athletes are specific to the sport, event group and age group; tailoring injury reduction programmes may therefore be possible. A large proportion of lost training and competition days were attributed to bone injuries; these should be targeted to a larger degree in risk factor studies and in injury reduction programmes. Skeletal maturity appears to affect the risk of sustaining certain injury types in football and athletics, while growth rates were only related to injury risk in athletics. Practitioners and researchers may need to consider the full growth and maturity process, rather than analysing short isolated periods, to better understand the relationship between growth, maturation and injury risk

Activity profiles in international female team handball using PlayerLoadTM

Team handball matches place diverse physical demands on players, which may result in fatigue and decreased activity levels. However, previous speed-based methods of quantifying player activity may not be sensitive for capturing short-lasting team handball-specific movements. Purpose: To examine activity profiles of a female team handball team and individual player profiles, using inertial measurement units (IMUs). Methods: Match data was obtained from one female national team in nine international matches (n=85 individual player samples), using the Catapult OptimEye S5. PlayerLoad™min-1 was used as a measure of intensity in 5- and 10-minute periods. Team profiles were presented as relative to the player’s match means, and individual profiles were presented as relative to the mean of the 5-minute periods with >60% field time. Results: A high initial intensity was observed for team profiles, and for players with ≥2 consecutive periods of play. Substantial declines in PlayerLoad™ min-1 were observed throughout matches for the team, and for players with several consecutive periods of field time. These trends were found for all positional categories. Intensity increased substantially in the final five minutes of the first half for team profiles. Activity levels were substantially lower in the five minutes after a player’s most intense period, and were partly restored in the subsequent 5-minute period. Discussion: Possible explanations for the observed declines in activity profiles for the team and individual players include fatiguing players, situational factors and pacing. However, underlying mechanisms were not accounted for, and these assumptions are therefore based on previous team-sport studies

Examination of Physical Characteristics and Positional Differences in Professional Soccer Players in Qatar

Physical characteristics in professional soccer differ between competition levels and playing positions, and normative data aid practitioners in profiling their players to optimize performance and reduce injury risk. Given the paucity of research in Arabic soccer populations, the purpose of this study was to provide position-specific normative values for professional players competing in the Qatar Stars League. One hundred and ninety-five players completed a musculoskeletal assessment as part of an annual periodic health examination. Tests included measures of range of motion (hip, ankle, and hamstring), bilateral and unilateral jump performance, and quadriceps/hamstring (isokinetic/NordBord), hip adduction/abduction (eccentric), and groin (isometric) strength. Descriptive data were examined, and positional differences were analyzed using a one-way analysis of variance (ANOVA). Goalkeepers were significantly heavier (p &lt; 0.01), had a higher body mass index (p &lt; 0.05) than outfield positions and demonstrated greater absolute strength. Defenders were the strongest relative to body mass, and these differences were significant (p &lt; 0.05) versus goalkeepers and strikers. No meaningful between-group comparisons were apparent for jumping or range of motion tests. Compared to mean values from other professional leagues, soccer players in Qatar appear to be shorter, lighter and display inferior strength and jump capacities. These data can be used to tailor training and rehabilitation programs to the specifics of the league and position in which the athletes compete

Skeletal maturation and growth rates are related to bone and growth plate injuries in adolescent athletics

Injuries are common in elite adolescent athletics, but few studies have addressed risk factors for injury. Growth and maturation are potential risk factors in this population; however, the current body of literature is both inconclusive and considered at high risk of bias. The aim of this study was therefore to examine whether growth rate, maturity status, and maturity tempo are associated with injury risk in an elite sports academy. Anthropometric, skeletal maturity and injury data collected prospectively over four seasons (117 athlete-seasons) were included in the analyses. Growth rate for stature was associated with greater risk of bone (incidence rate ratio (IRR): 1.5 per one standard deviation increase above the mean; 95% CI: 1.1-1.9) and growth plate injuries (IRR: 2.1; 1.5-3.1). Growth rate for leg length was associated with greater overall injury risk (IRR: 1.3; 1.0-1.7) as well as the risk of bone (IRR: 1.4; 1.0-1.9) and growth plate injuries (IRR: 2.1; 1.4-3.0). Athletes with greater skeletal maturity, expressed as skeletal age (IRR: 0.6 per year; 0.5-0.9) and percentage of predicted mature height (IRR: 0.8 per percent increase; 0.7-1.0), were less prone to growth plate injuries. Rate of change in skeletal age was associated with an increased risk of bone injuries (IRR: 1.5; 1.0-2.3). The results of this study suggest that rapid growth in stature and leg length, skeletal maturity status, and maturity tempo represent risk factors for certain injury types in adolescent athletics

Injury characteristics in male youth athletics: a five-season prospective study in a full-time sports academy

Objectives To describe the injury characteristics of male youth athletes exposed to year-round athletics programmes. Methods Injury surveillance data were prospectively collected by medical staff in a cohort of youth athletics athletes participating in a full-time sports academy from 2014-2015 to 2018-2019. Time-loss injuries (>1 day) were recorded following consensus procedures for athletics. Athletes were clustered into five event groups (sprints, jumps, endurance, throws and non-specialised) and the number of completed training and competition sessions (athletics exposures (AE)) were calculated for each athlete per completed season (one athlete season). Injury characteristics were reported overall and by event groups as injury incidence (injuries per 1000 AE) and injury burden (days lost per 1000 AE). Results One-hundred and seventy-eight boys (14.9±1.8 years old) completed 391 athlete seasons, sustaining 290 injuries. The overall incidence was 4.0 injuries per 1000 AE and the overall burden was 79.1 days lost per 1000 AE. The thigh was the most common injury location (19%). Muscle strains (0.7 injuries per 1000 AE) and bone stress injuries (0.5 injuries per 1000 AE) presented the highest incidence and stress fractures the highest burden (17.6 days lost per 1000 AE). The most burdensome injury types by event group were: bone stress injuries for endurance, hamstring strains for sprints, stress fractures for jumps, lesion of meniscus/cartilage for throws and growth plate injuries for non-specialised athletes. Conclusion Acute muscle strains, stress fractures and bone stress injuries were identified as the main injury concerns in this cohort of young male athletics athletes. The injury characteristics differed between event groups

Is the Acute: Chronic Workload Ratio (ACWR) Associated with Risk of Time-Loss Injury in Professional Team Sports? A Systematic Review of Methodology, Variables and Injury Risk in Practical Situations

Background: The acute: chronic workload ratio (ACWR) is an index of the acute workload relative to the cumulative chronic workloads. The monitoring of physical workloads using the ACWR has emerged and been hypothesized as a useful tool for coaches and athletes to optimize performance while aiming to reduce the risk of potentially preventable load-driven injuries. Objectives: Our goal was to describe characteristics of the ACWR and investigate the association of the ACWR with the risk of time-loss injuries in adult elite team sport athletes. Data sources: PubMed, EMBASE and grey literature databases; inception to May 2019. Eligibility criteria: Longitudinal studies that assess the relationship of the ACWR and time-loss injury risk in adult professional or elite team sports. Methods: We summarized the population characteristics, workload metrics and ACWR calculation methods. For each workload metric, we plotted the risk estimates for the ACWR in isolation, or when combined with chronic workloads. Methodological quality was assessed using a modified version of the Downs and Black scale. Results: Twenty studies comprising 2375 injuries from 1234 athletes (all males and mean age of 24 years) from different sports were included. Internal (65%) and external loads (70%) were collected in more than half of the studies and the session-rating of perceived exertion and total distance were the most commonly collected metrics. The ACWR was commonly calculated using the coupled method (95%), 1:4 weekly blocks (95%) and subsequent week injury lag (80%). There were 14 different binning methods with almost none of the studies using the same binning categories. Conclusion: The majority of studies suggest that athletes are at greater risk of sustaining a time-loss injury when the ACWR is higher relative to a lower or moderate ACWR. The heterogenous methodological approaches not only reflect the wide range of sports studied and the differing demands of these activities, but also limit the strength of recommendations

Involving research‐invested clinicians in data collection affects injury incidence in youth football

It is well established that differences in injury definition and recording methodology restrict comparisons between injury surveillance programmes. There is, however, little documentation of the variation that can exist between data recorders. The aim of this study was, therefore, to explore the effect on reported injuries when team recorders or supervisors are involved in research. Injury data collected prospectively over five seasons for the U16, U17, and U18 age groups in a youth football (soccer) academy were used to compare different recording settings based on the research involvement of the clinicians. A research‐invested team physiotherapist reported an 8.8 times greater incidence (P < 0.001) of non‐time‐loss injuries and a 2.5 times greater incidence (P < 0.001) of minimal injuries (1‐3 days lost) compared to a setting where neither the team physiotherapists nor the supervisor relied on the collected data for research purposes. When team physiotherapists were not invested in research themselves but were supervised by a researcher, the incidence of non‐time‐loss injuries and minimal injuries was 2.5 times (P < 0.001) and 2.0 times greater (P < 0.01) than in the non‐invested setting, respectively. However, there were no differences between recording settings for overall incidence of time‐loss injuries. The results from this study demonstrate that involving clinicians that are relying on the collected data for research purposes can significantly affect the reported rates of non‐time‐loss and minimal injuries. Time‐loss injuries overall were not affected by research investment, and should therefore be preferred for comparisons between teams and seasons