The combined effects of growth and maturity status on injury risk in an elite football academy.

This study aimed to explore the interaction between growth rate on specific injury incidence and burden on pre-, circa- and post-peak height velocity (PHV) periods. Injury and stature data collected during the 2000-2020 seasons in an elite football academy were retrospectively analysed. Only players with height measurements from childhood until the attainment of adult height were included in the study (N = 84). Growth data were smoothed using a cubic spline to calculate daily growth rate and height. Growth rate was categorised into three groups: fast (> 7.2 cm/year), moderate (3.5-7.2 cm/year) and slow (< 3.5 cm/year). Percentage of observed adult height was used to classify players as pre-PHV (< 88%), circa-PHV (88-95%) or post-PHV (> 95%). Overall and specific injury incidence and burden and rate ratios for comparisons between growth rate groups were calculated on pre-, circa- and post-PHV periods, separately. Overall injury incidence and burden were greater in pre-PHV players with quicker growth rates compared to players growing moderately and slowly. All in all, players with more rapid growth-rates were at higher risk for growth-related injuries in all pre-, circa- and post-PHV periods. Post-PHV, the incidence and burden of joint/ligament injuries were 2.4 and 2.6-times greater in players growing slowly compared to players growing moderately. Practitioners should monitor growth rate and maturity status and consider their interaction to facilitate the design of targeted injury risk reduction strategies.

An injury burden heat map of all men's and women's teams of a professional football club over a decade.

The aim was to present a descriptive 10-season summary of injury data from all teams of a professional football club using a heat map approach. Injuries and exposure time were registered according to the FIFA consensus in all men's and women's teams from Athletic Club over 10 seasons. A team-by-injury table was created, showing the incidence, median severity, and burden in each cell. Cells were coloured based on the injury burden value using a green - yellow-red gradient (lowest to highest). The highest overall injury burden was found in the women's 2nd and 1st teams and the men's U(under)17 team (>200 days lost/1000 h). Muscle injury burden demonstrated an increasing pattern with age. Knee joint/ligament injuries, particularly anterior cruciate ligament ruptures, had the highest impact on women's teams, followed by the men's 2nd team. In comparison, ankle joint/ligament injuries had a relatively low injury burden in most teams. Growth-related injuries were the most impactful injuries in the men's U15 and younger teams, and the women's U14 team. In conclusion, epidemiological data on injuries can inform and guide injury management processes. New and improved visualization methods might be important assets when presenting injury data to key decision-makers.

Pituitary Society Delphi Survey: An international perspective on endocrine management of patients undergoing transsphenoidal surgery for pituitary adenomas.

PURPOSE: In adults and children, transsphenoidal surgery (TSS) represents the cornerstone of management for most large or functioning sellar lesions with the exception of prolactinomas. Endocrine evaluation and management are an essential part of perioperative care. However, the details of endocrine assessment and care are not universally agreed upon. METHODS: To build consensus on the endocrine evaluation and management of adults undergoing TSS, a Delphi process was used. Thirty-five statements were developed by the Pituitary Society's Education Committee. Fifty-five pituitary endocrinologists, all members of the Pituitary Society, were invited to participate in two Delphi rounds and rate their extent of agreement with statements pertaining to perioperative endocrine evaluation and management, using a Likert-type scale. Anonymized data on the proportion of panelists' agreeing with each item were summarized. A list of items that achieved consensus, based on predefined criteria, was tabulated. RESULTS: Strong consensus (≥ 80% of panelists rating their agreement as 6-7 on a scale from 1 to 7) was achieved for 68.6% (24/35) items. If less strict agreement criteria were applied (ratings 5-7 on the Likert-type scale), consensus was achieved for 88% (31/35) items. CONCLUSIONS: We achieved consensus on a large majority of items pertaining to perioperative endocrine evaluation and management using a Delphi process. This provides an international real-world clinical perspective from an expert group and facilitates a framework for future guideline development. Some of the items for which consensus was not reached, including the assessment of immediate postoperative remission in acromegaly or Cushing's disease, represent areas where further research is needed.

Relative skeletal maturity status affects injury burden in U14 elite academy football players.

Maturation progresses at different times and at different rates between individuals. Thus, differences in maturity status exist among players in the same chronological age-based category, especially in U14 players. The purpose of this prospective study was to describe injury burden according to the relative skeletal maturity status in U14 elite academy football players. From 2011 to 2020, injuries and individual exposure (training and match) were prospectively recorded in 183 male U14 players. Skeletal age (SA) was assessed using the Tanner-Whitehouse 2 method. Relative skeletal maturity status [SA minus chronological age (CA)] was classified as follows: early (SA-CA > 0.5), on-time (SA-CA ± 0.5), and late (SA-CA < -0.5). Overall and specific injury burden (days lost/1000 h) and rate ratios for comparisons between groups were calculated. Overall injury burden was 2.8 times higher (3.6 times in training) in early maturers compared with late maturers. Growth-related injuries were the most burdensome injuries in all three groups, but significant differences were not found between groups. Muscle injuries were 4 times more burdensome in early maturers compared with on-time and late maturers. Besides, joint/ligament injuries were 7 and 12 times less burdensome in late maturers than in on-time and late maturers, respectively. Significant differences between groups in overall and specific injury burden were not found in matches. Our results showed different injury patterns in U14 early, on-time, and late maturers. Hence, monitoring maturity seems crucial to detect potential injuries that cause the greatest disruption, and facilitate design of targeted injury prevention programs.

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.

Effects of Massage and Cold Water Immersion After an Exhaustive Run on Running Economy and Biomechanics: A Randomized Controlled Trial.

ABSTRACT: Duñabeitia, I, Arrieta, H, Rodriguez-Larrad, A, Gil, J, Esain, I, Gil, SM, Irazusta, J, and Bidaurrazaga-Letona, I. Effects of massage and cold water immersion after an exhaustive run on running economy and biomechanics: A randomized controlled trial. J Strength Cond Res 36(1): 149-155, 2022-This study compares the effects of 2 common recovery interventions performed shortly after an exhausting interval running session on running economy (RE) and biomechanics. Forty-eight well-trained male runners performed an exhaustive interval running protocol and an incremental treadmill test 24 hours later at 3 speeds: 12, 14, and 16 km·h-1. Subjects randomly received either massage, cold water immersion (CWI), or passive rest (control). Runners repeated the treadmill test 48 hours after the first test. A two-way mixed analysis of variance was performed comparing groups and testing times. The massage group had significantly better recovery than the control group at 14 km·h-1 in RE (p < 0.05; η2 = 0.176) and greater stride height and angle changes at 16 km·h-1 (p < 0.05; η2 = 0.166 and p < 0.05; η2 = 0.208, respectively). No differences were observed between the CWI and control groups. The massage group had greater stride height and angle changes at 16 km·h-1 than the CWI group (p < 0.05; η2 = 0.139 and p < 0.05; η2 = 0.168, respectively). Moreover, differences in magnitude suggested moderate effects on RE (η2 = 0.076) and swing time (η2 = 0.110). These results suggest that massage intervention promotes faster recovery of RE and running biomechanics than CWI or passive rest.

Pituitary society guidance: pituitary disease management and patient care recommendations during the COVID-19 pandemic-an international perspective.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the viral strain that has caused the coronavirus disease 2019 (COVID-19) pandemic, has presented healthcare systems around the world with an unprecedented challenge. In locations with significant rates of viral transmission, social distancing measures and enforced 'lockdowns' are the new 'norm' as governments try to prevent healthcare services from being overwhelmed. However, with these measures have come important challenges for the delivery of existing services for other diseases and conditions. The clinical care of patients with pituitary disorders typically involves a multidisciplinary team, working in concert to deliver timely, often complex, disease investigation and management, including pituitary surgery. COVID-19 has brought about major disruption to such services, limiting access to care and opportunities for testing (both laboratory and radiological), and dramatically reducing the ability to safely undertake transsphenoidal surgery. In the absence of clinical trials to guide management of patients with pituitary disease during the COVID-19 pandemic, herein the Professional Education Committee of the Pituitary Society proposes guidance for continued safe management and care of this population.

Effects of 3 months of detraining on functional fitness and quality of life in older adults who regularly exercise.

BACKGROUND: Little is known about the effects of detraining in older adults, particularly those who regularly exercise. AIMS: To determine the consequences of 3 months of cessation of a habitual supervised exercise on functional fitness and quality of life in aged adults and to explore the associations among those parameters. METHODS: Thirty-eight women and 11 men (mean age 75.5 ± 5.7 years) took part in a physical exercise program for 9 months, followed by a 3-month detraining period. Participants completed physical function tests and questionnaires regarding the quality of life and leisure-time physical activity at the end of the exercise program (baseline) and 3 months later (detraining). RESULTS: After the detraining period, performance in the 8 Foot Up and Go test (p < 0.001) and the physical and mental components of the quality of life (p < 0.001) declined. Significant correlations were observed when comparing the 8 Foot Up and Go test (p < 0.05), Chair Stand test (p < 0.05), and the 6-min Walk test (p < 0.001) to the physical component of the quality of life after the detraining period. CONCLUSION: Three months of a detraining period in older people who habitually undertake supervised activities is enough to produce a decline in dynamic balance and also quality of life. To avoid the deleterious effect of periods of cessation of supervised exercise, as a suggestion, specifically designed exercises could be prescribed for an older population, with emphasis on balance exercises.

Relative age effect and left-handedness in world class water polo male and female players.

Most studies of the relative age effect (RAE) refer to popular sports. In contrast, we examined to what extent the RAE is present in elite water polo players, as well as the association between handedness and RAE. For these purposes, laterality, anthropometry, month of birth, performance and playing position of participants in the 2011, 2013 and 2015 World Championships (623 women, 622 men) were analised. No RAE was observed in the total sample. However, the proportion of male left-handed field players born in the first quarter (11%) was lower than those born in the second (35.3%) and fourth quarter (29.4%). Regarding the overall laterality, the amount of left handed players was similar to the general population (10%). Nevertheless, there was a larger amount of left-handed wings than expected both in men (23.7%) and women (34.4%). Left-handed male players performed more shots, shots/minute and also scored more goals than right-handed players. Women left-handed players were younger and they performed more shots/minute. There is no RAE in elite male and female water polo players. However, laterality could be a possible moderator of the RAE particularly in left handed players, which should be taken into account in future studies.

Progression in Youth Soccer: Selection and Identification in Youth Soccer Players Aged 13-15 Years.

Bidaurrazaga-Letona, I, Lekue, JA, Amado, M, and Gil, SM. Progression in youth soccer: Selection and identification in youth soccer players aged 13-15 years. J Strength Cond Res 33(9): 2548-2558, 2019-The aim of this study was to identify the factors that are important for the identification and selection of young soccer players. Ninety-four adolescent soccer players from the under-13 (U13; age = 12.3 ± 0.3 years; n = 50) and under-15 (U15; age = 14.0 ± 0.2 years; n = 44) categories belonging to a professional club participated in the study. Anthropometric measurements, physical tests (sprint, agility, endurance and jump), and maturity status (age at peak height velocity) were recorded over 4 seasons. Comparisons were performed among new players joining the club (Enter players, n = 15), players progressing to the next age category (Club players, n = 54), and players leaving the club (Deselected players, n = 25). A 2-way repeated measures analysis of variance (ANOVA) was performed to determine if significant differences existed between groups and testing time. Better physical performance and improvements observed during the season in performance were found to be one of the main factors for U13 players to continue in the club (p < 0.05-0.001). In the U15 group, although body size, maturation and physical performance appeared to be the most important characteristics for being identified to play in the club (p < 0.05), Club players demonstrated better improvements during the season (p < 0.05). Overall, these results indicate that the identification or promotion of players by coaches depends on indicators which are age-dependent. Therefore, this study has shown that the talent identification program was more a selection process than a promotion process, selecting and identifying a posteriori rather than a priori.

Does a 1-Year Age Gap Modify the Influence of Age, Maturation, and Anthropometric Parameters as Determinants of Performance Among Youth Elite Soccer Players?

Bidaurrazaga-Letona, I, Lekue, JA, Amado, M, and Gil, SM. Does a 1-year age gap modify the influence of age, maturation, and anthropometric parameters as determinants of performance among youth elite soccer players? J Strength Cond Res 33(9): 2541-2547, 2019-Because age-groups in soccer often comprise children born within a 2-year time frame, characteristics that define the profile of a successful player may not be appropriate for the oldest or youngest players of the same age-group. Therefore, this study aimed to determine to what extent performance was influenced by age, maturation, and body size in elite soccer players with barely 1-year age gap. Anthropometry, 15-m sprint test, modified Barrow's agility test, Yo-Yo intermittent recovery test level 1, countermovement jump, and handgrip test were conducted in players aged 12 years and under (n = 82; age, 11.1 ± 0.6 years) and between 12 and 13 years (n = 79; age, 12.8 ± 0.6 years). A total score of performance, chronological age, and age at peak height velocity were calculated. Descriptive statistics, Student's t-tests, and multiple linear regressions were performed. The explained variance in composite score was greater in the older (54%) than in the younger (30%) players. Sum of skinfolds was the primary predictor of 15-m sprint and countermovement jump in the younger group, whereas in the older group, chronological age and body size appeared as predictors of performance (41%). Body size explained the variance in most tests in older players. In the younger group, biological maturity status explained the variance in endurance (35%) and handgrip (59%) tests. In summary, chronological age and sum of skinfolds influenced the most tests; however, predictors differed between age groups. These findings highlight the importance of assessing individual differences in young male soccer players regardless of their similarity in age.

Prediction of performance by heart rate-derived parameters in recreational runners.

We investigated whether heart rate (HR)-derived parameters are accurate performance predictors in endurance recreational runners. One hundred thirty recreational athletes completed an incremental running test (4´running + 1´rest). After each stage, we recorded HR, % of maximum HR (%HRmax), and blood lactate. We also assessed HR after each recovery period, and calculated lactate and HR recovery thresholds and HR deflection point. We tested these parameters for associations with running performance, as measured by peak treadmill speed (PTS) and personal best International Association of Athletics Federations (IAAF) score. The %HRmax at 14.5 km·h-1 correlated with PTS (r = -0.92), and IAAF score (rho = -0.80). The magnitudes of the correlations of lactate-related parameters with PTS (|r| = 0.84 to 0.86) or IAAF score (|rho| = 0.70 to 0.77) in absolute values were slightly lower. The correlations detected between other HR-derived parameters and running performance were weaker (|r or rho| = 0.24 to 0.70). Regression models identified %HRmax at 14.5 km·h-1 as the strongest predictor of both PTS (ß = -0.72) and IAAF score (ß = -0.72). Consequently, tests based on %HRmax may provide a non-invasive and inexpensive alternate method for predicting the performance of these athletes.

Anthropometric Parameters, Age, and Agility as Performance Predictors in Elite Female Basketball Players.

Garcia-Gil, M, Torres-Unda, J, Esain, I, Duñabeitia, I, Gil, SM, Gil, J, and Irazusta, J. Anthropometric parameters, age, and agility as performance predictors in elite female basketball players. J Strength Cond Res 32(6): 1723-1730, 2018-In addition to technical, tactical, and psychological skills, performance in playing basketball depends on anthropometry and physical fitness. However, limited information is available regarding such features in women. We hypothesized that anthropometry and physical fitness are associated with female basketball performance, and consequently, performance could be predicted using the results of certain anthropometric measures and fitness tests. Body parameters (age, height, body mass, skinfold thicknesses, limb perimeters, and lengths) were measured. Physical fitness capacities (jumping, agility with and without the ball, and speed) were measured by specific tests. In addition, game performance was assessed using technical statistics (rebounds, assists, and points) and the performance index rating (PIR). Teams ranked better in the regular season had smaller mean fat skinfold thickness and spent less time in the agility tests (T-Drill). Correlation analyses indicated that players with better PIR were older, taller, and had a longer arm span and greater contracted arm perimeter (CAP). Furthermore, those players had better results in the T-Drill test. Multiple regression analysis indicated that combined age, height, CAP, fat skinfold thickness, and time in T-Drill test yielded a strong predictor of PIR per time played. In conclusion, the results of the present study indicate that some anthropometric and physical fitness characteristics of female elite basketball teams and players are highly associated with performance-related parameters. In addition, a regression model has been developed to predict the performance of female basketball players.

Pubertal development of body size and soccer-specific functional capacities in adolescent players.

Pubertal growth in body size and functional capacities were examined in adolescent soccer players (n = 33). The average age at baseline was 10.9 (9.8-11.8 years). Peak height velocity (PHV) and growth curves for body mass and functional performance (countermovement jump, 15-m sprint, agility and Yo-Yo intermittent recovery test - level 1) were determined with Bayesian multilevel models. Estimates for PHV and age at PHV were 8.1 cm/year (95% credible interval: 4.2-18.5 cm/year) and 12.9 years (95% credible interval: 11.8-15.5 years), respectively. Peak body mass velocity occurred 0.48 year after PHV. Jump performance maximum velocity occurred about 2 years after PHV and peak sprint performance maximum velocity was coincident with PHV. Agility and intermittent endurance run performance showed a quadratic trend of improvement of performance, starting to level off at about 3-4 years after PHV. The modelling procedures were efficient to determine pubertal growth curves aligned for chronological age and age at PHV, considering individual differences in maturation when interpreting the development of performance in youth soccer.

Basketball Performance Is Related to Maturity and Relative Age in Elite Adolescent Players.

During a national championship, the anthropometric, physiological, and maturation characteristics of 13- to 14-year-old players of elite basketball teams and their association with sport performance were analyzed. Body parameters (weight, height, skinfold thicknesses, and lengths) were measured and physiological capacities assessed by sprint (20 m) and jump tests (i.e., countermovement jump with arm swing). Chronological age (CA) and maturity offset (years from age at peak height velocity; YAPHV) were calculated, and then predicted age at peak height velocity, as the difference between CA and YAPHV. Game performance was assessed with point averages and the performance index rating (PIR). The birth-date distribution of players was biased, those born early in the selection year outnumbering those born later. Anthropometric analysis indicated that players who performed better had longer body lengths. Physiological testing showed that semi-finalists had better sprint performance than quarter-finalists and those players with greater jump capacity scored more points. Early maturation and advanced maturity status were also associated with better PIR and scored points per game. Multiple blockwise regression analysis showed that, among the factors analyzed, YAPHV was the best predictor of basketball performance. In conclusion, around puberty, physical and physiological parameters associated with maturity and CA are important in determining the success of elite basketball players. Consequently, boys who are born in the second half of the year and/or late maturing tend to be marginalized or totally excluded, and not given the chance to play under equal conditions; their careers may then be held back by the relative disadvantage associated with inexperience.

Anthropometry and Performance in Wheelchair Basketball.

This study investigated whether anthropometric characteristics, generic and specific sprinting, agility, strength, and endurance capacity could differentiate between First-Division and Third-Division wheelchair basketball (WB) players. A First-Division WB team (n = 8; age = 36.05 ± 8.25 years, sitting body height = 91.38 ± 4.24 cm, body mass = 79.80 ± 12.63 kg) and a Third-Division WB team (n = 11; age = 31.10 ± 6.37 years, sitting body height = 85.56 ± 6.48 cm, body mass = 71.18 ± 17.63 kg) participated in the study. Wheelchair sprint, agility, strength, and endurance tests were performed. The First-Division team was faster (8.7%) in 20 m without the ball, more agile (13-22%), stronger (18-33%), covered more distance (20%) in the endurance test, and presented higher values of rate of perceived exertion for the exercise load (48%) than the Third-Division team. Moreover, the individual 20-m sprint time values correlated inversely with the individual strength/power values (from r = -0.54 to -0.77, p ≤ 0.05, n = 19). Wheelchair basketball coaches should structure strength and conditioning training to improve sprint and agility and evaluate players accordingly, so that they can receive appropriate training stimuli to match the physiological demands of their competitive level.

Stride angle as a novel indicator of running economy in well-trained runners.

The main purpose of this study was to investigate the relationship between a novel biomechanical variable, the stride angle, and running economy (RE) in a homogeneous group of long-distance athletes. Twenty-five well-trained male runners completed 4-minute running stages on a treadmill at different set velocities. During the test, biomechanical variables such as stride angle, swing time, ground contact time, stride length, stride frequency, and the different sub-phases of ground contact were recorded using an optical measurement system. VO2 values at velocities below the lactate threshold were measured to calculate RE. Stride angle was negatively correlated with RE at every speed (p < 0.001, large effect sizes). Running economy was also negatively correlated with swing phase and positively correlated with ground contact time and running performance according to the best 10-km race time (p ≤ 0.05, moderate and large effect sizes). Last, stride angle was correlated with ground contact time at every speed (p < 0.001, large effect sizes). In conclusion, it seems that optimal execution of stride angle allows runners to minimize contact time during ground contact, whereby facilitating a better RE. Coaches and/or athletes may find stride angle a useful and easily obtainable measure to track and make alterations to running technique, because changes in stride angle may influence the energy cost of running and lead to improved performance.

Physical growth and changes in intermittent endurance run performance in young male Basque soccer players.

The present 4-year longitudinal study examined physical growth and development of intermittent endurance run performance in young Basque soccer players aged 10-15 years applying multilevel regression modeling. Anthropometry, predicted adult stature and Yo-Yo Intermittent Recovery level 1 test (Yo-Yo IR1) of players from the under-11 teams from the Athletic Club of Bilbao were measured at pre- and end-season (two measurements per year of study, n = 33 considered for analysis). A non-linear effect of age on intermittent endurance run was observed, with significantly higher increases in Yo-Yo IR1 between 10-11 year-old and 14-15 year-old players. The development of Yo-Yo IR1 performance in all the years of the study was influenced positively by training exposure during the seasons (P < 0.01) and independent of maturity status and body size (P > 0.05). The steady development of intermittent endurance run performance during pubertal years in adolescent Basque soccer players is partially influenced by training exposure.

Lost in transition: Exploring injury risk in academy footballers shifting between the second and first teams.

OBJECTIVES: To compare the injury profiles of football players shifting between second and first teams with those of second- and first-team players, and to examine the opinions of shifting players. DESIGN: Prospective cohort study. METHODS: 170 male players from Athletic Club (second team = 90, shifting = 20, first team = 60) were followed over eight seasons. Injuries and exposure time were recorded following the FIFA consensus, and 18 shifting players answered a seven-item questionnaire on their experience. RESULTS: 35 % shifting players became full-time first-team players, in contrast to only 8 % of second-team players (odds ratio = 6.4, p < 0.01). There were no differences in the overall injury incidence, but the overall burden of injuries was higher in second-team (172 days lost/1000 h) and shifting players (194 days lost/1000 h) compared with first-team players (114 days lost/1000 h, p < 0.01). Shifting players had a higher burden of knee joint/ligament injuries compared with first-team players (137 vs. 18 days lost/1000 h, p < 0.01) and anterior cruciate ligament (ACL) ruptures (122 vs. 10 days lost/1000 h, p < 0.01). There was a trend towards a higher burden of ACL ruptures in shifting players than in second-team players (122 vs. 41 days lost/1000 h, p = 0.07). Shifting players reported constant pressure and better communication with the second-team coaching staff than with the first-team staff. CONCLUSIONS: The high burden of injuries in shifting players, particularly from ACL ruptures, highlights the need for action. Ensuring high-quality communication between second- and first-team staff remains a key challenge.

Estimating Maturity Status in Elite Youth Soccer Players: Evaluation of Methods.

PURPOSE: The objective of this study is to evaluate the concordance of predicted maturity status classifications (pre-, circa-, or post-peak height velocity (PHV)) relative to observed age at PHV in youth soccer players. METHODS: Longitudinal height records for 124 male soccer players were extracted from academy records spanning the 2000 to 2022 seasons. Age at PHV for each player was estimated with the Superimposition by Translation and Rotation model. Players were classified as pre-, circa-, or post-PHV using both ±1- and ±0.5-yr criteria to define the circa-PHV interval. Maturity status was estimated with several prediction protocols: maturity offset (Mirwald, Moore-1, Moore-2), maturity ratio (Fransen), and percentage of predicted adult height (PAH%) using the Khamis-Roche and Tanner-Whitehouse 2 equations using several bands: 85% to 96%, 88% to 96%, 88% to 93%, and 90% to 93% for the circa-PHV interval, and visual evaluation of individual growth curves alone or with PAH% based on Khamis-Roche and Tanner-Whitehouse 2. Concordance of maturity status classifications based on complete growth curves and predicted estimates of maturity status was addressed with percentage agreement and Cohen's kappa. RESULTS: Visual evaluation of the growth curves had the highest concordance (≈80%) with maturity status classifications (pre-, circa-, post-PHV) based on longitudinal data for individual players. Predicted maturity offset with the Mirwald, Moore-1, and Fransen equations misclassified about one-third to one-half of the players, whereas concordance based on PAH% varied with the band used, but not with the method of height prediction. CONCLUSIONS: Visual assessment of the individual growth curves by an experienced assessor provides an accurate estimate of maturity status relative to PHV. Maturity offset prediction equations misclassify the majority of players, whereas PAH% provides a reasonably valid alternative.