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.

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.

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.

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.

What Are the Load and Wellness of Young Second-Team Football Players When Transitioning to the First Team? A Comparison of 2 Consecutive Preseasons.

PURPOSE: To compare the load and wellness of second-team academy football players during a first-team preseason with those of first-team players and those of their previous second-team preseason. METHODS: Athletic Club's first- (n = 10) and second-team (n = 9) players were prospectively followed during the 2019-20 first- and second-team and 2020-21 first-team preseasons. Weekly external and internal loads and average wellness z-scores (fatigue, sleep quality, muscle soreness, stress, and mood) were compared between preseasons and teams. RESULTS: While training together during the 2020-21 preseason, second-team players performed more decelerations <-3 m/s2 per week than first-team players (moderate effect size). For first-team players, there were only small differences between preseasons in external load, but session rating of perceived exertion was higher (moderate) and stress (moderate) and mood (large) z-scores were worse in 2020-21. For second-team players, more total distance (large), accelerations >3 m/s2 (large), and decelerations <-3 m/s2 (very large) were performed; total loading (moderate) and session rating of perceived exertion (moderate) were higher; and fatigue (very large) and stress (moderate) z-scores were worse during the 2020-21 first-team preseason compared to their previous second-team preseason. CONCLUSIONS: Players transitioning from the second team faced higher external and internal loads, fatigue, and stress during the first-team preseason compared to the previous second-team preseason. Player development and monitoring plans appear necessary to manage the transition from the academy to the first team.

Effect of Baduanjin on physical functioning and balance in adults with mild-to-moderate intellectual disabilities: A comparative study.

BACKGROUND: Adults with intellectual disabilities often experience mobility limitations. Baduanjin, a mindfulness-based exercise intervention, can exert positive effects on functional mobility and balance. This study examined the impact of Baduanjin on physical functioning and balance of adults with intellectual disabilities. METHOD: Twenty-nine adults with intellectual disabilities participated in the study. Eighteen received a Baduanjin intervention for 9-months; 11 participants did not receive any intervention (comparison group). Physical functioning and balance were assessed using the short physical performance battery (SPPB) and stabilometry. RESULTS: Participants in the Baduanjin group experienced significant changes in the SPPB walking test (p = .042), chair stand test (p = .015), and SPPB summary score (p = .010). No significant changes between groups were observed in any of the variables assessed at the end of the intervention. CONCLUSIONS: Baduanjin practice may cause significant, albeit small, improvements in physical functioning of adults with intellectual disabilities.

Peak Height Velocity Affects Injury Burden in Circa-PHV Soccer Players.

Growth and maturation are potential risk factors for soccer injuries. This research sought to describe how peak height velocity (PHV) affects overall and specific injury burden in circa- and post-PHV elite academy soccer players. Injuries and growth data collected from 2000 to 2020 were studied retrospectively. Longitudinal height records for 124 players were fitted with the Super-Imposition by Translation and Rotation model to calculate PHV (cm/year) and age at PHV. Players were classified according to PHV percentile (fast:≥75th; average: 25-75th; slow:≤25th) and maturity status (circa- or post-PHV). Overall and specific injury burden (days lost/player-season) and rate ratios for comparisons between groups were calculated based on zero-inflated negative binomial models. Confidence intervals were calculated at the 95% confidence level (CI) and the significance level was set at<0.05. In circa-PHV, players with fast PHV had 2.6 (CI: 1.4-4.8)- and 3.3 (CI:1.3-6.7)-times higher overall burden and 2.9 (CI:1.1-7.1)- and 4.1 (CI: 1.4-15.2)-times higher for growth-related injury burden compared to players with average and slow PHV, respectively. Regular monitoring of growth seems important to detect players at higher risk for being disrupted by growth-related injuries.

The burden of injuries according to maturity status and timing: A two-decade study with 110 growth curves in an elite football academy.

Injuries have a negative impact on the development of football players. Maturation is a potential risk factor for football injuries but available data on this topic provide limited evidence due to methodological shortcomings. The aim of this study was to describe the injury burden of male academy football players according to growth curve-derived maturity status and timing. Injury and growth data were collected from 2000 to 2020. Longitudinal height records for 110 individual players were fitted with the Super-Imposition by Translation and Rotation model to estimate age at peak height velocity (PHV). Players were clustered according to maturity status (pre-, circa-, post-PHV, or adults) and timing (early, on-time, late maturers). Overall and specific injury burdens (days lost/player-season) and rate ratios for comparisons between groups were calculated. Overall injury burden increased with advanced maturity status; pre-PHV players had 3.2-, 3.7-, and 5.5-times lower burden compared with circa-PHV, post-PHV, and adult players, respectively. Growth-related injuries were more burdensome circa-PHV, while muscle and joint/ligament injuries had a higher impact post-PHV and in adults. Further, in the pre-PHV period, late maturers showed lower burden of overall, growth-related, anterior inferior iliac spine osteochondrosis, and knee joint/ligament injuries compared with on-time maturers. In adult players, however, injuries were less burdensome for early maturers than on-time and late maturers. In addition, joint/ligament injuries of adult late maturers were 4.5-times more burdensome than those of early maturers. Therefore, monitoring maturity seems crucial to define each player's maturation profile and facilitate design of targeted injury prevention programmes.Highlights Injury burden is significantly lower in football players at pre-peak height velocity (PHV). Growth-related injuries are most burdensome circa-PHV, while muscle and joint/ligament injuries are more burdensome post-PHV and especially in adults.Before PHV, growth-related and knee joint/ligament injuries have lower burden in players who mature late than those who mature on-time. Adult late maturers have greater burden of overall and joint/ligament injuries than early maturers.Football academies should regularly assess the maturity status and timing of young football players, as the impact of injuries varies with maturation status and timing.Management of the maturity-related injury risk profile, in combination with other relevant factors (training load, neuromuscular and biomechanical factors, physiotherapy, coaching, communication, psychosocial factors …), might help improve the success of player development programmes and protect the health of young football players.

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.