Biological maturity influences running performance in junior Australian football

Longitudinal Development of Sprint Performance and Force-Velocity-Power Characteristics: Influence of Biological Maturation

ABSTRACT

Edwards, T, Weakley, J, Banyard, HG, Cripps, A, Piggott, B, Haff, GG, and Joyce, C. Longitudinal development of sprint performance and force-velocity-power characteristics: influence of biological maturation. J Strength Cond Res 37(11): 2178-2184, 2023-This study was designed to investigate the influence of biological maturation on the longitudinal development of sprint performance. Thirty-two subjects performed 2 assessments of maximal sprint performance that were separated by 18 months. Each sprint assessment was measured through a radar gun that collected instantaneous velocity with the velocity-time data used to derive sprint times and force-velocity-power characteristics. The biological maturity of each subject was assessed using a predictive equation, and subjects were grouped according to predicted years from peak height velocity (circa-PHV: -1.0 to 1.0; post-PHV: >1.0). A 2 × 2 mixed model analysis of variance was used to assess group × time interactions, and paired t -tests were used to assess the longitudinal changes for each maturity group. No significant group × time interactions were observed for any sprint time or force-velocity-power characteristic. The circa-PHV group experienced significant within-group changes in maximal theoretical velocity (6.35 vs. 5.47%; effect size [ES] = 1.26 vs. 0.52) and 5-m sprint time (-3.63% vs. -2.94%; ES = -0.64 vs. -0.52) compared with the post-PHV group. There was no significant change in the magnitude of relative theoretical maximum force in either group; however, both the circa-PHV and post-PHV groups significantly improved the orientation of force production at the start of the sprint (RFmax [4.91 vs. 4.46%; ES = 0.79 vs. 0.74, respectively]). Considering these findings, it is recommended that practitioners adopt training methods aimed to improve relative lower-limb force production, such as traditional strength training and sled pulling and pushing, to improve sprint performance and relative theoretical maximum force.

In-situ acceleration-speed profile of an elite soccer academy: A cross-sectional study

Speed is an essential skill in sports performance and an important performance metric in talent identification. This study aims to evaluate and compare the sprint acceleration characteristics across different age groups in an elite soccer academy. A total of 141 elite academy soccer players were recruited to participate in the study, and they were assigned to their respective competitive age groups, ranging from under-14 to the B-team. An individual in-situ acceleration-speed (A-S) profile was assessed and derived from Global Position System (GPS) speed-acceleration raw data, from 10 consecutive football sessions, in the beginning of the season. The results showed that under-14 players exhibited significantly lower theoretical maximum speed (S0) (η p 2  = 0.215, p < 0.01) when compared with all other age groups. However, no differences were found between maximum theoretical acceleration (A0) and A-S slope between age groups. The results suggest that sprint mechanical profiles of young soccer athletes remain stable throughout their athletic development. Nevertheless, younger athletes have less capacity to apply horizontal force at higher speeds (S0).

Sprint acceleration characteristics across the Australian football participation pathway

The aim of this study was to compare the force, velocity and power profiles of a maximal sprint acceleration through different competition levels of the Australian Football (AF) participation pathway. One hundred and sixty-two junior AF athletes across five competition levels including State under 18's (ST 18), State under 16's (ST 16), local under 18's (LOC 18), local under 15's (LOC 15), and local under 14's (LOC 14) participated in this cross-sectional study. Velocity-time data from maximal sprint accelerations were analysed to derive athlete's sprint acceleration characteristics and split times. ST 18 showed a more force-orientated profile than the LOC 18 with moderate differences in relative theoretical maximal force (F0) (7.54%), absolute F0 (10.51%), and slope of the force-velocity relationship (Sf-v) (9.27%). Similarly, small differences were found between ST 18 and ST 16 in relative F0 (4.79%) and Sf-v (6.28%). Moderate to extremely large differences were observed between players competing in older (ST 18, LOC 18, ST 16) compared to younger (LOC 15, LOC 14) competition levels highlighting the potential influence of biological maturation. It is recommended that practitioners working with junior AF players to consider developing a force-orientated sprint acceleration profile to improve sprinting performance.

Does maturity estimation, 2D:4D and training load measures explain physical fitness changes of youth football players?

OBJECTIVES

The purpose of the present study was two-fold: (1) To analyse physical fitness changes of youth football players after a full-season; and (2) to examine whether physical fitness changes are explainable by estimated maturity status, 2digit:4digit ratio (2D:4D) from each hand and training load (TL) measures.

METHODS

Twenty-seven youth elite Under-15 football players were daily monitored for training load measures during 38 weeks. At the beginning and at the end of the season, all players were assessed for physical fitness. Also, the maturity status estimation and the length of the second and fourth digits of both hands were collected at the beginning of the season.

RESULTS

Significant differences were found for all physical fitness measures after the season. The second and fourth digits of left and right hands had negative moderate correlations with change of direction (COD) changes (r=-.39 to - 0.45 | p = .05 to 0.02). Also, the maturity offset measure had negative moderate correlations with COD changes (r=-.40 | p = .04). From the reported significant correlations, the maturity offset, Left 4D, Right 2D and Right 4D significantly predicted the Mod.505 COD test changes (β = 0.41, p = .04; β = -0.41, p = .04; β = -0.45, p = .02; and β = -0.44, p = .03, respectively).

CONCLUSION

The maturity offset and the 2D:4D measures have the potential to predict COD performance changes over-time in youth football players. Given the lack of associations between the maturity estimation, 2D:4D and training load measures, with the overall physical fitness measures, coaches should rely only at COD changes.

The influence of maturation, fitness, and hormonal indices on minutes played in elite youth soccer players: a cross-sectional study

Background

The main purpose of this study was to investigate the relationships between minutes played (MP) with maturity status, fitness, and hormonal levels, and to quantify their influence on minutes played.

Methods

Twenty-four elite youth soccer players under-16 years participated in this study, over a full-season period. Anthropometric measures, maturity status, hormonal and physical fitness levels were collected. Participants were monitored during the season. After the end-season, players were assessed in 6 different tests over a four-day period.

Results

The maximum oxygen consumption (V̇O_2max) was strongly correlated with MP (r = 0.75), maturity offset (r = 0.52), and countermovement jump (r = 0.53). Multiple linear regression explained 76% of MP (F (8, 15) = 6.05, p = 0.001), with an R2 of 0.76. Moreover, Growth hormone (GH) and V̇O_2max. were the most influential factors in MP (F (2, 21) = 17.92, p ≤ 0.001), with an R2 of 0.63.

Conclusion

High levels of GH and V̇O_2max have a preponderant role in MP by elite youth soccer players, it appears to be more pragmatic to consider other contextual dimensions, as they can impact selection for competition and minutes of participation in a match.

Age-Related Differences in the Anthropometric and Physical Fitness Characteristics of Young Soccer Players: A Cross-Sectional Study

Considering that most professional academies seek to optimize the early detection and physical development of their younger players, the purpose of this study was to examine the anthropometric and physical fitness characteristics in a large cross-sectional sample of youth soccer players in Eastern Europe, starting from a very young age during their in-season period. Three hundred and thirteen soccer players (n = 313), grouped into eight age categories, participated in the study. On the basis of chronological age, the group categories were: 7 (n = 26), 8 (n = 41), 9 (n = 46), 10 (n = 48), 11 (n = 42), 12 (n = 47), 13 (n = 43), and 14 years old (n = 20). The players underwent an anthropometric evaluation, flexibility, handgrip strength, vertical jump performance, speed, and agility assessments. A one-way multivariate analysis of variance (MANOVA) indicated significant differences in the anthropometric and physical fitness variables based on chronological age (F = 13.40, p < 0.05, Wilk’s Λ = 0.08, partial η2 = 0.30). Concurrently, there were significant growth and physical fitness differences even in players born in the same chronological year. It is believed that the results have important practical implications, especially for those involved in youth soccer. Based on our results, coaches should contemplate speed and agility development in training sessions starting from a much younger age, as sprinting while changing directions has been considered an essential prerequisite in soccer.

Associations between match participation, maturation, physical fitness, and hormonal levels in elite male soccer player U15: a prospective study with observational cohort

OBJECTIVES

The aims of this study were to analyze the relationships between minutes of play (MP) and maturity status, fitness, and hormonal levels and to explain how those measures influence the time of play.

METHODS

Twenty-six youth soccer players U15 participated in this study over a full-season period. Anthropometric measures, maturity status, growth hormone (GH), insulin-like growth factor and physical levels such as maximal oxygen uptake (VO2max), fatigue index, countermovement jump (CMJ) performance were collected. At the end-season, players were assessed in 6 different tests over four days.

RESULTS

VO2max largely correlated with GH (r = 0.57) and CMJ (r = 0.51). Also, GH largely correlated with CMJ (r = 0.55). MP had moderate correlations with VO2max (r = 0.44) and CMJ (r = 0.42). Multiple linear regression with maturation, physical fitness and hormonal levels explained R2 of 0.62 of the MP (F (8, 17) = 3.47, p = 0.015). Although each independent variable alone was not able to determine the playing time, when using the interactions, the model significantly explained the MP.

CONCLUSIONS

The combination of maturity status, physical fitness, and hormonal levels seem to play a determinant role in explaining the match participation in youth soccer players.

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.

Maturity-Associated Differences in Match Running Performance in Elite Male Youth Soccer Players

PURPOSE

To investigate the influence of maturation on match running performance in elite male youth soccer players.

METHODS

A total of 37 elite male youth soccer participants from an English professional soccer academy from the U14s, U15s, and U16s age groups were assessed over the course of 1 competitive playing season (2018-2019). Relative biological maturity was assessed using percentage of predicted adult height. A global positioning system device was used between 2 and 30 (mean = 8 [5]) times on each outfield player. The position of each player in each game was defined as defender, midfielder, or attacker and spine or lateral. A total of 5 match-running metrics were collected total distance covered, high-speed running distance, very high-speed running distance, maximum speed attained, and number of accelerations.

RESULTS

Relative biological maturity was positively associated with all global positioning system running metrics for U14s. The U15/16s showed variation in the associations among the global positioning system running metrics against maturity status. A multilevel model which allowed slopes to vary was the best model for all parameters for both age groups. In the U14 age group, advanced maturation was associated with greater high-speed running distance. However, maturation did not contribute toward variance in any of the indices of running performance in the U15/16s. In the U15/16 age group, significance was observed in the spine/lateral playing positions when undertaking actions that required covering distance at high speeds.

CONCLUSIONS

Maturation appeared to have an impact on match-running metrics within the U14s cohort. However, within the U15/16s, the influence of maturation on match-running metrics appeared to have less of an impact.

Examination of the Sprinting and Jumping Force-Velocity Profiles in Young Soccer Players at Different Maturational Stages

The aim was to determine the relationships among components of the force-velocity (F-V) profiles in jumping and sprinting, with both biological and chronological ages in 89 young soccer players belonging to categories from U10 to U18. Participants performed countermovement jumps (CMJ) and 20-m sprint tests. F-V components assessed were associated with both maturity offset and chronological age, using correlation and multiple linear regression analyses. Horizontal (i.e., maximal theoretical force [F0] and velocity [V0], maximal power [Pmax] and F-V slope) and vertical (i.e., [F0] and [Pmax]) F-V components displayed very large correlations (i.e., 0.79 ≤ r ≤ 0.92) with both chronological age and maturity offset. The combination of sprinting Pmax and training experience and jumping F0 and training experience explained up to 94% of the variances in maturity offset and chronological age. Furthermore, similar correlations were found between sprinting and jumping performances, and components of the F-V profiles, and both maturity offset and chronological age. Identification of vertical jump and sprint mechanical determinants may assist in strengthening those components of the F-V profile which are weaker throughout the training process. Sprinting and jumping capabilities can be indistinctly monitored with respect to their chronological age or maturity offset in young soccer players.

Exploring Relationships Between Anthropometry, Body Composition, Maturation, and Selection for Competition: A Study in Youth Soccer Players

Purpose

The purpose of this study was to analyze variations of selection for competition between late and early mature players and test the relationships between anthropometry, body composition, maturation, and selection for competition.

Methods

Seventy-nine youth soccer players from under-11 to under-14 participated in this study, over 6 months. Body composition and maturity offset were estimated based on anthropometric data collected. Participants were also monitored for their number of matches as starters and time of play accrued in minutes.

Results

Minutes played had large correlation coefficients with maturity offset (r = 0.58), and leg length and sitting height interaction (r = 0.56). Multiple linear regression explained 35% of the variation in minutes played (p < 0.001, R² = 0.41, R²_adjusted = 0.35, RMSE = 334.8), but only 12% of the variation in matches as starter (p = 0.04, R² = 0.21, R²_adjusted = 0.12, RMSE = 5.47) between above and below the median of the maturity offset was accounted for, respectively.

Conclusions

Although maturation may play a role in the minutes of play accrued and matches as starters in young, it is not necessarily determining. A significant amount of the variation in the minutes of play accrued of players can be accounted for when considering body composition and anthropometric data.

Relationship between Biological Maturation, Physical Fitness, and Kinanthropometric Variables of Young Athletes: A Systematic Review and Meta-Analysis

There is a growing interest in knowing the relationship between biological maturation and sport performance-related variables of young athletes. The objective of this study is to analyze the relationship between biological maturation, physical fitness, and kinanthropometric variables of athletes during their growing period, according to their sex. The systematic review and meta-analysis followed the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement and the search protocol was registered in PROSPERO, code: CRD42020208397. A search through the PubMed, Web of Sciences, and EBSCO databases was performed. A total of 423 studies were screened and 13 were included in the meta-analysis. The meta-analysis was completed by using the mean and standard deviation of each variable according to each maturation status (early, on time, or late). Differences depending on maturation were found on physical fitness, with better results in the advanced maturational groups in the male population (standard mean difference (SMD) = 0.17-2.31; p < 0.001-0.05). Differences depending on maturation were found for kinanthropometric variables in males (SMD = 0.37-2.31; p < 0.001-0.002) and height and body mass in females (SMD = 0.96-1.19; p < 0.001). In conclusion, the early maturation group showed higher values in kinanthropometric variables and better results in physical fitness, highlighting the importance of the maturational process in the talent selection programs. Despite that, more research is needed to clarify the relationship of maturation with the other variables on female populations and the changes in the muscle and bone variables during the maturation processes of both sexes.

Normative Data and Physical Determinants of Multiple Sprint Sets in Young Soccer Players Aged 11-18 Years: Effect of Maturity Status

Selmi, MA, Sassi, RH, Yahmed, MH, Giannini, S, Perroni, F, and Elloumi, M. Normative data and physical determinants of multiple sprint sets in young soccer players aged 11-18 years: Effect of maturity status. J Strength Cond Res 34(2): 506-515, 2020-The aims of the study were: (a) to establish normative data for repeated-sprint sets (RSS) test based on the maturity status (age at peak height velocity [PHV]) and (2) to investigate the relationship between anthropometrical variables (stature, sitting height, body mass, and body fat percentage), RSS (2 × 5 × 20 m with 15-second recovery between sprints and 1-minute recovery between sets), and fitness tests {squat jump, countermovement jump, standing long jump, standing triple jump, 5-jump test, and 20-m shuttle run (multistage shuttle run test [MSRT])}. Young male soccer players (n = 262; age: 14.5 ± 2.9 years) were evaluated and classified into 4 groups according to their maturity status: pre-PHV, circum-PHV1, circum-PHV2, post-PHV. An analysis of variance and Bonferroni post hoc were used to determine maturity group differences (p ≤ 0.05), whereas Pearson's correlation was used between variables. Repeated-sprint sets' indices (sum of sprint times [SST] and best sprint time [BST]) were significantly different between the maturity groups. Significant correlations between SST with body mass (from -0.73 to -0.33) and MSRT (from -0.49 to -0.30) among each maturity group were found. With the different maturity groups, correlations between SST (s), BST (s), and vertical jump (cm) (r = -0.63 to -0.25 and r = -0.68 to -0.23) and horizontal jump (m) (r = -0.70 to -0.38 and r = -0.63 to -0.43) were observed. Repeated-sprint sets' values improve during maturation of young soccer players and the correlations between RSS and fitness tests vary through the maturity groups. This information could be useful for the coach to identify talent and to prescribe specific physical training to improve performance.

Classification of Players Across the Australian Rules Football Participation Pathway Based on Physical Characteristics

Haycraft, JAZ, Kovalchik, S, Pyne, DB, and Robertson, S. Classification of players across the Australian Rules football participation pathway based on physical characteristics. J Strength Cond Res XX(X): 000-000, 2020-This study investigated the utility of physical fitness and movement ability tests to differentiate and classify players into Australian Football League (AFL) participation pathway levels. Players (n = 293, age 10.9-19.1 years) completed the following tests; 5-m, 10-m, and 20-m sprint, AFL planned agility, vertical jump (VJ), running VJ, 20-m multistage fitness test (MSFT), and athletic ability assessment. A multivariate analysis of variance between AFL participation pathway levels was conducted, and a classification tree determined the extent to which players could be allocated to relevant levels. The magnitude of differences between physical fitness and movement ability were level-dependent, with the largest standardized effect size (ES) between Local U12, Local U14, and older levels for most physical fitness tests (ES: -4.64 to 5.02), except the 5-m and 10-m sprint. The 20-m, 5-m, AFL agility, 20-m MSFT, overhead squat, and running VJ (right) contributed to the classification model, with 57% overall accuracy reported (43% under cross-validation). National U16 players were easiest to classify (87%), while National U18 players were most difficult (0%). Physical fitness tests do not seem to differentiate between players after selection into AFL talent pathway levels. Other attributes (i.e., skill, psychological, and sociocultural) should be prioritized over physical fitness and movement attributes by selectors/coaches when considering selection of talented players.

Relationships Between Physical Testing and Match Activity Profiles Across the Australian Football League Participation Pathway

Purpose: To establish levels of association between physical fitness and match activity profiles of players in the Australian Football League (AFL) participation pathway. Methods: Players (N = 287, range 10.9-19.1 y) were assessed on 20-m sprint, AFL agility, vertical jump and running vertical jump, 20-m multistage fitness test (MSFT), and Athletic Abilities Assessment. Match activity profiles were obtained from global positioning system measures: relative speed, maximal velocity, and relative high-speed running. Results: Correlational analyses revealed moderate relationships between sprint (r = .32-.57, P ≤ .05) and jump test scores (r = .34-.78, P ≤ .05) and match activity profiles in Local U12, Local U14, National U16, and National U18s, except jump tests in National U18s. AFL agility was also moderate to strongly associated in Local U12, Local U14, Local U18, and National U16s (r = .37-.87, P ≤ .05) and strongly associated with relative speed in Local U18s (r = .84, P ≤ .05). Match relative speed and high-speed running were moderate to strongly associated with 20-m MSFT in Local U14, Local U18, and National U18s (r = .41-.95, P ≤ .05) and Athletic Abilities Assessment in Local U12 and Local U18s (r = .35-.67, P ≤ .05). Match activity profile demands increased between Local U12 and National U16s, then plateaued. Conclusions: Physical fitness relates more strongly to match activity profiles in younger adolescent and national-level players. Recruiters should consider adolescent physical fitness and match activity profiles as dynamic across the AFL participation pathway.

Fundamental Motor Skills Mediate the Relationship Between Physical Fitness and Soccer-Specific Motor Skills in Young Soccer Players

Fundamental motor skills (FMS) are the basic elements of more complex sport-specific skills and should be mastered at the end of early childhood; however, the relationship between FMS and sport-specific skills has not yet been verified in prepubertal soccer players. Therefore, the aim of this study was to determine the role of FMS in the process of acquiring soccer-specific motor skills (measured using speed dribbling) with regard to physical fitness and biological maturation. Forty male soccer players (11.5 ± 0.3 years of age) at the highest performance level participated in the study. The test of Gross Motor Development - second edition and Unifittest 6-60 were used to assess FMS and physical fitness, respectively. The role of FMS in a complex theoretical model with the relationships between physical fitness, biological maturation and speed dribbling was analyzed by multiple regression path analyses (MRPA). Moderate to strong correlations were found between FMS, physical fitness, and speed dribbling (r = 0.56-0.66). Biological maturation did not appear to be a significant predictor of physical fitness or speed dribbling. The MRPA model using FMS as mediator variable between physical fitness and speed dribbling showed a significant indirect effect (standard estimation = -0.31, p = 0.001; R 2 = 0.25). However, the direct correlation between physical fitness and speed dribbling was non-significant. Our results showed that FMS significantly strengthened the influence of physical fitness on the performance of speed dribbling, a soccer-specific motor skill, and thus play an important role in the process of acquiring sport-specific motor skills in prepubertal soccer players. When considering the long-term training process, especially during childhood and before puberty, a wide range of FMS activities should be applied for better and possibly faster acquisition of soccer-specific motor skills.

Biological maturation and match running performance: A national football (soccer) federation perspective

OBJECTIVES

To examine the influence of maturation and its interaction with playing position upon physical match performances in U15 footballers from a national federation.

DESIGN

Observational study.

METHODS

278 male outfield players competing in a national tournament were assessed for somatic maturity and match physical performances according to playing position. Stature, sitting height, and body mass were measured and entered into an algorithm to estimate the age at peak height velocity (APHV). Players match movements were recorded by Global Positioning System devices (10 Hz), to determine peak speed, and total- (TD), low-speed running (LSR; ≤13.0 km h^-1), high-speed running (HSR; 13.1-16.0 km h^-1), very high-speed running (VHSR; 16.1-20.0 km h^-1) and sprint distances (SPR; >20.0 km h^-1) expressed relative to match exposure (m min^-1).

RESULTS

Linear-mixed models using log transformed response variables revealed a significant contribution of estimated APHV upon TD (1.01; 95% CI: 0.99-1.02 m·min^-1; p < 0.001), HSR (1.05; 95% CI: 0.98-1.13 m min^-1; p < 0.001) and VHSR (1.07; 95% CI: 1.00-1.14 m min^-1; p = 0.047). An increase by one year in APHV was associated with an increase of 0.6, 5.4 and 6.9% in TD, HSR and VHSR respectively. No effects of APHV were observed for LSR, SPR, and peak speed. Further, no APHV effects were observed relative to players' field position.

CONCLUSIONS

Later maturing players covered substantially more higher-intensity (HSR and VHSR) running in matches, irrespective of playing position. The greater match intensity of later maturing players may inform talent identification and athletic development processes within a national federation.

Training Loads and RSA and Aerobic Performance Changes During the Preseason in Youth Soccer Squads

The aims of this study were to compare the internal training load (ITL) in soccer players of two competitive age groups (under-15 [U-15] and under-19 [U-19]) during an 8-week preseason training period and compare the associated changes in physical performance measures. Eighteen U-15 and twelve U-19 players were monitored over an 8-week period during the preseason phase. The ITL was monitored using the session rating of perceived exertion (RPE) method. Before and after the preseason period, physical performance was assessed by best (RSA_best) and mean (RSA_mean) times in a repeated sprint ability (RSA) test and peak velocity derived from the Carminatti test (PVT-CAR). Total weekly ITL increased with age (U-15: 13770 ± 874 AU vs. U-19: 33584 ± 2506 AU; p < 0.001). In addition, U-19 players perceived training sessions as heavier than U-15 players (6.1 ± 0.3 vs. 5.3 ± 0.3 AU, respectively; p < 0.001). After the preseason period, very likely to almost certainly positive changes were observed for all performance measures in both age groups. However, the U-15 group had possibly superior gains in RSA_best (+1.40%, 90%CL -0.29 to 3.05, with ES = 0.35) and likely higher effects in RSA_mean (+1.89%, 90%CL 0.04 to 3.70, with ES = 0.53) and PV_T-CAR (+2.71%, 90%CL 0.35 to 5.01, with ES = 0.37) compared to the U-19 group. In conclusion, our findings demonstrate that the U-19 group accumulate higher total weekly ITLs than the U-15 group during the preseason phase due to longer and heavier training sessions. However, the U-15 group obtained superior gains in soccer-specific physical abilities while accumulating half the total ITLs during lighter training sessions.

A multidimensional approach to talent identification and selection in high-level youth Australian Football players

There is limited research in talent identification in youth Australian Football (AF), especially the factors that underpin selection into higher-level development programs. Therefore, this study explored age-related differences in high-level youth AF players and investigated characteristics influencing selection into a high-level development program. Anthropometry (stature, sitting height, body mass), maturity (estimated age at peak height velocity), motor competence (Körperkoordinationstest für Kinder), fitness (change of direction speed, lower body power and upper body muscular endurance) and coach skill ratings (kicking, marking and handballing) of 277 state academy players (U13-U15) were assessed. MANOVAs identified significant age-related differences for anthropometry, fitness, and coach skill ratings. Furthermore, 90.9 and 90.0% of U15 selected and deselected players were classified correctly. Selected players were more mature, taller, heavier, more explosive, faster at changing directions, and had superior kick technique and marking results. These results demonstrate considerable age-group performance outcome differences, highlighting that high-level academies should aim to select or deselect after 15 years of age. Additionally, it appears earlier maturing players are favoured for selection into a high-level academy. While practitioners must consider the confounding effect of maturation, early maturing players may be favoured for their ability to withstand increasing demands in higher-level youth AF.

Functional Movements in Japanese Mini-Basketball Players

Functional movement screen (FMS) has been used to establish normative data and determine potential injury risk for young adults and athletes, but there are few data in elementary school-age children. The purpose of this study was to establish fundamental values for the FMS in elementary school-age mini-basketball players. Secondary purposes were to examine relationships between functional movement patterns and age, peak height velocity (PHV), and body mass index (BMI), and to compare functional movement patterns between boys and girls and between individuals with and without a history of injury. The mean composite FMS score was 16.5 ± 2.2 (16.5 ± 2.4 for boys, 16.5 ± 1.7 for girls). The composite FMS score was positively correlated with age (r = .312) and negatively correlated with the BMI (r = − .371). However, the FMS score was not correlated with PHV or with PHV age. The FMS score was not different between boys and girls or between individuals who reported a previous injury and those who did not. However, boys in the mini-basketball teams performed better than girls on the trunk stability push-up and rotary stability tests. Age and the body mass index were significantly associated with better and poorer functional movement, respectively.

The influence of age-policy changes on the relative age effect across the Australian Rules football talent pathway

OBJECTIVES

To identify the influence of age-policy changes on the relative age effect (RAE) across the Australian Football League (AFL) talent pathway.

DESIGN

Retrospective cross-sectional analysis of junior AFL players attending the National Draft (National), State, and State Under 16s (U16) combines between 1999-2016.

METHODS

Birth-date data was obtained for players attending the AFL State U16 (n=663, age: 15.9±0.4years), State (n=803, age: 19.1±1.7years), National (n=1111, age: 18.3±0.8years) combines. Corresponding aged-matched Australian general population birth rate data was also collected.

RESULTS

A chi-squared analysis comparing birth month distributions found all combine groups differed significantly from the general population (Under 16s: χ²=62.61, State: χ²=38.83, National: χ²=129.13, p<0.001). Specifically, Under 16s had greater birth frequencies for months January to March (≥2%, p<0.05), with more State players born in January (4.9%, p<0.05). Age-policy changes at the National level reduced birth distribution bias for some months, however the RAE remained for March, June and July (3.9%, 6.1%, 4.3%, p<0.05). State U16s and National players had 2-9% lower birth frequencies for November-December births compared general population.

CONCLUSIONS

Selection bias exists towards older players is present at the AFL's State U16, and is maintained at State and National level combines. Age-policy changes are only partially successful at addressing the RAE at the National level, with alternative strategies also recommended in order to address the RAE across the AFL talent pathways.

Physical characteristics of players within the Australian Football League participation pathways: a systematic review

Background

Australian football (AF) players require endurance, strength, speed, and agility to be successful. Tests assessing physical characteristics are commonly used for talent identification; however, their ability to differentiate between players across the Australian Football League’s (AFL) participation pathway remains unclear. The objective of this review was to quantify the physical characteristics of male AF players across the AFL participation pathway.

Methods

A search of databases was undertaken. Studies examining tests of physical performance were included, with 27 meeting the inclusion/exclusion criteria. Study appraisal was conducted using a checklist of selection criteria.

Results

The 20-m sprint time was the most reported test, followed by vertical jump (VJ), AFL planned agility, and 20-m multi-stage fitness test (MSFT). The fastest times for 20-m sprint were for Elite AFL players (range 2.94–3.13 s), with local-level players the slowest (3.22–4.06 s). State Junior Under (U) 18s (58–66 cm) had higher jumps than senior players, with the lowest jumps reported for Local U10s (mean 31 cm). No elite-level data were reported for the AFL planned agility or 20-m MSFT. AFL planned agility times were only reported for talent pathway levels, with large performance variability evident across all levels (8.17–9.12 s). Only mean 20-m MSFT scores were reported from Local U10s to National Draft Camp (6.10–13.50 shuttles).

Conclusions

Talent pathway players exhibit similar mean test scores irrespective of the physical test, with the exception of 20-m sprint and VJ. Physical tests can discriminate between local participation level players but are less useful within the AFL talent pathway.

Identifying the Physical Fitness, Anthropometric and Athletic Movement Qualities Discriminant of Developmental Level in Elite Junior Australian Football: Implications for the Development of Talent

Gaudion, SL, Doma, K, Sinclair, W, Banyard, HG, and Woods, CT. Identifying the physical fitness, anthropometric and athletic movement qualities discriminant of developmental level in elite junior Australian football: implications for the development of talent. J Strength Cond Res 31(7): 1830-1839, 2017-This study aimed to identify the physical fitness, anthropometric and athletic movement qualities discriminant of developmental level in elite junior Australian football (AF). From a total of 77 players, 2 groups were defined according to their developmental level; under 16 (U16) (n = 40, 15.6 to 15.9 years), and U18 (n = 37, 17.1 to 17.9 years). Players performed a test battery consisting of 7 physical fitness assessments, 2 anthropometric measurements, and a fundamental athletic movement assessment. A multivariate analysis of variance tested the main effect of developmental level (2 levels: U16 and U18) on the assessment criterions, whilst binary logistic regression models and receiver operating characteristic (ROC) curves were built to identify the qualities most discriminant of developmental level. A significant effect of developmental level was evident on 9 of the assessments (d = 0.27-0.88; p ≤ 0.05). However, it was a combination of body mass, dynamic vertical jump height (nondominant leg), repeat sprint time, and the score on the 20-m multistage fitness test that provided the greatest association with developmental level (Akaike's information criterion = 80.84). The ROC curve was maximized with a combined score of 180.7, successfully discriminating 89 and 60% of the U18 and U16 players, respectively (area under the curve = 79.3%). These results indicate that there are distinctive physical fitness and anthropometric qualities discriminant of developmental level within the junior AF talent pathway. Coaches should consider these differences when designing training interventions at the U16 level to assist with the development of prospective U18 AF players.

Modelling height in adolescence: a comparison of methods for estimating the age at peak height velocity

BACKGROUND

Controlling for maturational status and timing is crucial in lifecourse epidemiology. One popular non-invasive measure of maturity is the age at peak height velocity (PHV). There are several ways to estimate age at PHV, but it is unclear which of these to use in practice.

AIM

To find the optimal approach for estimating age at PHV.

SUBJECTS AND METHODS

Methods included the Preece & Baines non-linear growth model, multi-level models with fractional polynomials, SuperImposition by Translation And Rotation (SITAR) and functional data analysis. These were compared through a simulation study and using data from a large cohort of adolescent boys from the Christ's Hospital School.

RESULTS

The SITAR model gave close to unbiased estimates of age at PHV, but convergence issues arose when measurement error was large. Preece & Baines achieved close to unbiased estimates, but shares similarity with the data generation model for our simulation study and was also computationally inefficient, taking 24 hours to fit the data from Christ's Hospital School. Functional data analysis consistently converged, but had higher mean bias than SITAR. Almost all methods demonstrated strong correlations (r > 0.9) between true and estimated age at PHV.

CONCLUSIONS

Both SITAR or the PBGM are useful models for adolescent growth and provide unbiased estimates of age at peak height velocity. Care should be taken as substantial bias and variance can occur with large measurement error.

Rule modification in junior sport: Does it create differences in player movement?

OBJECTIVES

To determine the effects of rule modification on player movement during matchplay in junior Australian football (AF).

DESIGN

Quasi-experimental study design.

METHODS

Time-motion analysis was used to record variables pertaining to player movement including total distance covered, high-speed running (HSR) distance (>14.4km/h) and HSR efforts. GPS data obtained from 145 players (7-12 years) were analysed across four junior AF leagues and three age group combinations (U8/U9, U9/U10 and U11/U12). The four leagues were collapsed into two separate conditions (compliant and non-compliant) based on their adherence to a modified junior sport policy. To control for the influence of age and physical maturity, a secondary analysis was performed on an adequately matched U8 subset of data (n=48).

RESULTS

Significant differences (p<0.05) were found between compliant and non-compliant leagues for age and all player movement variables, with participants in the compliant leagues achieving less player movement. Significant differences were also evident between conditions in the U8 subset in total and relative distance and HSR efforts, with moderate to very large differences (29-60%) observed for all player movement variables.

CONCLUSIONS

Rule modifications limits the extent and intensity of player movement in junior AF compared to standard playing conditions. The unintended effect of reduced physical activity with rule modifications should be compensated for with additional activities wherever possible. League administrators and policy makers should consider the objectives of rule modifications and weigh up both positive and negative outcomes.

Match running performance and skill execution improves with age but not the number of disposals in young Australian footballers

This study investigated age-related differences in maturity, physical and functional characteristics and playing performance in youth Australian Football (AF). Young male players (n = 156) were recruited from 12 teams across 6 age groups (U10-U15) of a recreational AF club. All players were tested for body size, maturity and fitness. Player performance was assessed during a match in which disposals (kicks and handballs) and their effectiveness were coded from a video recording and match running performance measured using Global Positioning System. Significant main effects (P < 0.01) for age group were observed for age, years to peak height velocity, body mass, height, 20 m sprint, maximal speed over 20 m, vertical jump, 20 m multistage shuttle run, match distance, high-speed running distance, peak speed, number of effective disposals and percentage of effective disposals. Age-related differences in fitness characteristics (speed, lower body power and endurance) appeared to transfer to match running performance. The frequency in which players disposed of the football did not differ between age groups, however the effectiveness of each disposal (i.e., % effective disposals) improved with age. Match statistics, particularly those that evaluate skill execution outcome (i.e., effectiveness), are useful to assess performance and to track player development over time. Differences between age groups, and probably variability within age groups, are strongly associated with chronological age and maturity.

At What Age Do Children and Adolescents Develop Lower Limb Tendon Pathology or Tendinopathy? A Systematic Review and Meta-analysis

BACKGROUND

Tendon pathology and tendinopathy have been reported in children and adolescents; however, the age at onset and prevalence of the conditions have not been examined systematically.

OBJECTIVE

To examine the prevalence of lower limb tendon pathology and tendinopathy in children and adolescents, and the factors associated with these conditions in this population.

METHODS

Six databases were searched (MEDLINE, the Cochrane Central Register of Controlled Trials, Embase, Scopus, the Web of Science and the Allied and Complementary Medicine Database). Studies were included if the prevalence of lower limb tendon pathology and/or tendinopathy were reported in humans under the age of 18 years. Studies were divided according to the method of diagnosis (physical examination, ultrasound or a questionnaire) and further divided into studies that reported prevalence data by tendon [reported two data points (right and left) for each participant] and those that reported prevalence data for each participant [reporting one data point (right or left) per participant].

RESULTS

Seventeen studies met the inclusion criteria. Lower limb tendinopathy prevalence (presence of pain and dysfunction) ranged between 8.2 and 33.3%, and increased in prevalence as age increased up to 18 years. The odds ratio for studies reporting tendinopathy by tendon was 0.37 (95% confidence interval 0.20-0.69) in favour of boys presenting with tendinopathy. Study aims and reporting methods were heterogeneous.

CONCLUSIONS

The age at onset of lower limb tendinopathy in children and adolescents has not been widely studied. This systematic review found that tendinopathy is present in children and adolescents, and increases in prevalence with age up to 18 years. Male sex is significantly associated with tendinopathy in studies that report tendinopathy by tendon.

Comparison of anthropometry, upper-body strength, and lower-body power characteristics in different levels of Australian football players

The aim of this study was to compare the anthropometry, upper-body strength, and lower-body power characteristics in elite junior, sub-elite senior, and elite senior Australian Football (AF) players. Nineteen experienced elite senior (≥4 years Australian Football League [AFL] experience), 27 inexperienced elite senior (<4 years AFL experience), 22 sub-elite senior, and 21 elite junior AF players were assessed for anthropometric profile (fat-free soft tissue mass [FFSTM], fat mass, and bone mineral content) with dual-energy x-ray absorptiometry, upper-body strength (bench press and bench pull), and lower-body power (countermovement jump [CMJ] and squat jump with 20 kg). A 1-way analysis of variance assessed differences between the playing levels in these measures, whereas relationships between anthropometry and performance were assessed with Pearson's correlation. The elite senior and sub-elite senior players were older and heavier than the elite junior players (p ≤ 0.05). Both elite playing groups had greater total FFSTM than both the sub-elite and junior elite players; however, there were only appendicular FFSTM differences between the junior elite and elite senior players (p < 0.001). The elite senior playing groups were stronger and had greater CMJ performance than the lower level players. Both whole-body and regional FFSTM were correlated with bench press (r = 0.43-0.64), bench pull (r = 0.58-0.73), and jump squat performance measures (r = 0.33-0.55). Australian Football players' FFSTM are different between playing levels, which are likely because of training and partly explain the observed differences in performance between playing levels highlighting the importance of optimizing FFSTM in young players.

Comparison of resistance training progression models on maximal strength in sub-elite adolescent rugby union players

OBJECTIVES

To determine changes in maximal strength between two different resistance training progression models, linear (LP) and daily undulating (DUP), over a 12-week resistance training programme in sub-elite adolescent rugby union players.

DESIGN

The study used a quasi-experimental study design. Following baseline assessments, participants from Squad 1 were randomised to either LP or DUP; participants from Squad 2 formed a non-randomised comparison group (CON).

METHODS

Participants were 26 sub-elite adolescent rugby union players who were assessed at baseline and after 12 weeks. Outcomes included 5 repetition maximum (RM) box squat and bench press, height, body weight, skeletal muscle mass, percentage body fat and maturation status.

RESULTS

Participants in both the LP and DUP groups significantly increased their squat and bench press strength from baseline to 12 weeks. There were no significant differences between groups for squat and bench press increases after 12 weeks (p>0.05). No significant increases in squat or bench press strength were observed after 12 weeks in the CON group. Increases in lower body strength were large in the LP group (ES: 1.64) and very large in the DUP group (ES: 2.33). Upper body strength changes were small in both groups (LP, ES: 0.57; DUP, ES: 0.31).

CONCLUSIONS

Twelve weeks of LP or DUP resistance training are both effective at increasing maximal lower and upper body strength in adolescent rugby athletes. Additionally, twice weekly frequency of resistance training in adolescent rugby athletes with greater than 6-months resistance training experience is sufficient to elicit substantial increases in maximal strength.

The relationship between workloads, physical performance, injury and illness in adolescent male football players

BACKGROUND

The expectation that training enhances performance is well explored in professional sport. However, the additional challenges of physical and cognitive maturation may require careful consideration when determining workloads to enhance performance in adolescents.

OBJECTIVE

The objective of this study was to determine the state of knowledge on the relationship between workloads, physical performance, injury and/or illness in adolescent male football players.

METHODS

A systematic review of workloads, physical performance, injury and illness in male adolescent football players was conducted. Studies for this review were identified through a systematic search of six electronic databases (Academic Search Complete, CINAHL, PsycINFO, PubMed, SPORTDiscus, and Web of Science). For the purpose of this review, load was defined as the cumulative amount of stress placed on an individual from multiple training sessions and games over a period of time, expressed in terms of either the external workloads performed (e.g., resistance lifted, kilometres run) or the internal response (e.g., heart rate, rating of perceived exertion) to that workload.

RESULTS

A total of 2,081 studies were initially retrieved from the six databases, of which 892 were duplicates. After screening the titles, abstracts and full texts, we identified 23 articles meeting our criteria around adolescent football players, workloads, physical performance, injury and/or illness. Seventeen articles addressed the relationship between load and physical performance, four articles addressed the relationship between load and injury and two articles addressed both. A wide range of training modalities were employed to improve the physical performance of adolescent football players, with strength training, high-intensity interval training, dribbling and small-sided games training, and a combination of these modalities in addition to normal football training, resulting in improved performances on a wide range of physiological and skill assessments. Furthermore, there was some (limited) evidence that higher workloads may be associated with the development of better physical qualities, with one study demonstrating enhanced submaximal interval shuttle run performance with each additional hour of training or game play. Of the few studies examining negative consequences associated with workloads, increases in training load led to increases in injury rates, while longer training duration was associated with a greater incidence of illness.

CONCLUSION

The combined capacity for adolescent males to grow, train and improve physical performance highlights and underscores an exciting responsiveness to training in the football environment. However, the capacity to train has some established barriers for adolescents experiencing high workloads, which could also result in negative consequences. Additional research on stage-appropriate training for adolescent male footballers is required in order to address the knowledge gaps and enhance safe and efficient training practices.

Gender's Effect on a School-Based Intervention in The Prepubertal Growth Spurt

Children aged 10-11 years pass through a dynamic developmental period marked by rapid changes in body size, shape, and composition, all of which are sexually dimorphic. The purpose of this study was to analyze the effects of gender on a school-based intervention in the prepubertal growth spurt. One hundred twenty-five healthy children (58 boys, 67 girls), fifth and sixth grade students from an urban public elementary school in Portugal (10.8 ± 0.4 years), were randomly assigned into two experimental groups: a strength training group (19 boys, 22 girls), and an endurance training group (21 boys, 24 girls); and a control group (18 boys, 21 girls; no training program). Training program for the two experimental groups was conducted twice a week for 8 weeks. Compared with the values at the beginning of the protocol, both strength and endurance training programs produced significant improvements (p< 0.05) in vertical and horizontal jumps, a 1 kg and 3 kg medicine ball throw, a 20 m sprint and VO2max, for both boys and girls. No significant changes were observed related to gender in training-induced strength (p> 0.05, η_p^2= 0.16, Power= 0.29) and aerobic (p> 0.05, η_p^2= 0.05, Power= 0.28) capacity. The results of the present study should be taken into consideration in order to optimize strength training school-based programs.

Effects of age, maturity and body dimensions on match running performance in highly trained under-15 soccer players

The aim of the present study was to compare, in 36 highly trained under-15 soccer players, the respective effects of age, maturity and body dimensions on match running performance. Maximal sprinting (MSS) and aerobic speeds were estimated. Match running performance was analysed with GPS (GPSport, 1 Hz) during 19 international friendly games (n = 115 player-files). Total distance and distance covered >16 km h(-1) (D > 16 km h(-1)) were collected. Players advanced in age and/or maturation, or having larger body dimensions presented greater locomotor (Cohen's d for MSS: 0.5-1.0, likely to almost certain) and match running performances (D > 16 km h(-1): 0.2-0.5, possibly to likely) than their younger, less mature and/or smaller teammates. These age-, maturation- and body size-related differences were of larger magnitude for field test measures versus match running performance. Compared with age and body size (unclear to likely), maturation (likely to almost certainly for all match variables) had the greatest impact on match running performance. The magnitude of the relationships between age, maturation and body dimensions and match running performance were position-dependent. Within a single age-group in the present player sample, maturation had a substantial impact on match running performance, especially in attacking players. Coaches may need to consider players' maturity status when assessing their on-field playing performance.

Differentiating maturational influence on training-induced strength and endurance adaptations in prepubescent children

OBJECTIVE

To analyze the effect of biological maturation on training-induced strength and endurance adaptations in the prepubertal growth spurt.

METHODS

One hundred and twenty-five healthy children (58 boys, 67 girls), aged 10-11 years old (10.8 ± 0.4 years), who were self-assessed as belonging to Tanner stages I and II, were randomly divided into two experimental groups, a strength training group (19 boys, 22 girls) and an endurance training group (21 boys, 24 girls) that would train twice a week for 8 weeks, as well as a control group (18 boys, 21 girls; no training program).

RESULTS

After 8 weeks of training, there were improvements in all strength and endurance measures (P < 0.01) for both groups of Tanner stage I and II children. No significant differences in training response were observed relative to biological maturity or gender (P > 0.05).

CONCLUSIONS

These data suggest that more biologically mature prepubescent children seem to have no advantage in training-induced strength and endurance adaptations compared with their less mature peers. Additionally, gender did not affect the training-induced changes in strength or aerobic fitness. These results are meaningful for the development of optimized well-rounded training programs in prepubertal children. Am. J. Hum. Biol. 26:469-475, 2014. © 2014 Wiley Periodicals, Inc.

Pubertal development, spare time activities, and adolescent delinquency: testing the contextual amplification hypothesis

Extensive evidence supports associations between early pubertal timing and adolescent externalizing behavior, but how and under which conditions they are linked is not fully understood. In addition, pubertal development is also characterized by variations in the relative speed at which individuals mature, but studies linking pubertal 'tempo' and outcomes are scarce. This study examined the mediating and moderating roles of spare time activities in associations between pubertal development and later delinquency, using data from a large (4,327 girls, 4,250 boys) longitudinal UK cohort (Avon Longitudinal Study of Parents and Children). Self-reports of Tanner stage were available from ages 9 to 14, spare time activities at age 12 and delinquency at age 15. Pubertal development was examined using latent growth models. Spare time activities were categorized using factor analyses, yielding four types (hanging out at home, hanging out outside, consumerist behavior, and sports/games), which were examined as mediators and moderators. Earlier and faster maturation predicted delinquency in boys and girls. Spare time activities partially mediated these links such that early maturing girls more often engaged in hanging out outside, which placed them at greater risk for delinquency. In addition, compared to their later and slower maturing counterparts, boys who matured earlier and faster were less likely to engage in sports/games, a spare time activity type that is linked to lower delinquency risk. No moderation effects were found. The findings extend previous research on outcomes of early maturation and show how spare time activities act as proxies between pubertal development and delinquency.