Age and maturity related differences in motor coordination among male elite youth soccer players

The Effect of Sex, Maturity, and Training Status on Maximal Sprint Performance Kinetics

PURPOSE

The development of sprint running during youth has received renewed interest, but questions remain regarding the development of speed in youth, especially the influences of sex, training, and maturity status.

METHODS

One hundred and forty-seven team sport trained (69 girls; 14.3 [2.1] y) and 113 untrained (64 girls; 13.8 [2.7] y) youth completed two 30-m sprints separated by 2-minute active rest. Velocity was measured using a radar gun at >46 Hz, with power and force variables derived from a force-velocity-power profile.

RESULTS

Boys produced a significantly higher absolute peak power (741 [272] vs 645 [229] W; P < .01) and force (431 [124] vs 398 [125] N; P < .01) than girls, irrespective of maturity and training status. However, there was a greater sex difference in relative mean power and peak velocity in circa peak height velocity adolescents (46.9% and 19.8%, respectively) compared with prepeak height velocity (5.4% and 3.2%) or postpeak height velocity youth (11.6% and 5.6%).

CONCLUSIONS

Sprint development in youth is sexually dimorphic which needs considering when devising long-term training plans. Further research is needed to explore the independent, and combined, effects of sex, training, and maturity status on sprint performance kinetics in youth.

Kinetic and Kinematic Characteristics Underpinning Change of Direction Performance in Basketball: A Comparative Study Between Sexes and Tests

ABSTRACT

Baena-Raya, A, Díez-Fernández, DM, Martínez-Rubio, C, Conceição, F, and López-Sagarra, A. Kinetic and kinematic characteristics underpinning change of direction performance in basketball: A comparative study between sexes and tests. J Strength Cond Res 38(4): e182-e188, 2024-This study (a) evaluated the sex-specific kinetic and kinematic outcomes underpinning change of direction (COD) performance, (b) compared these outcomes across 3 different COD tests, and (c) examined the sex-specific and test-specific outcome most strongly related to COD performance in basketball players. Thirty young basketball players (17 males and 13 females) competing at the national level were assessed for the modified 505 test, modified T test, and V-cut test. The Local Positioning System technology (WIMU PRO, Realtrack Systems S.L., Almería, Spain) was used to measure the maximum values of acceleration (ACC max ), deceleration (DEC max ), velocity (VEL max ), and centripetal force (CentF max ) in each COD test. Male players displayed greater ACC max , VEL max , DEC max , and CentF max outputs for each section of the 505 test, T test, and V-cut test (all p < 0.05), resulting in a faster COD performance than females across tests (all ES > -1.42; 95% CI = -3.45 to -0.57). The 505 test demanded significantly greater kinematic outputs than T test and V-cut test for both sexes ( p < 0.01). The ACC max explained ∼26-58% of the variability in COD time for males across tests ( p < 0.05) and 40% in females' modified 505-test time ( p < 0.05). Likewise, in females, DEC max explained 38% of the modified T -test time variability, whereas VEL max explained 53% in the V-cut test time (both p < 0.05). These findings suggest that (a) COD data should not be used interchangeably across sexes, (b) test specificities should be considered for designing COD training, and (c) the kinematic outcomes explaining COD performance might vary across sexes.

Associations between biological maturation, physical performance, postural control, and mathematical achievement in youth soccer players

This investigation explored relationships between biological maturation, physical and academic performance in young male soccer players. Thirty-eight players (age: 9.79 ± 1.21 years; body mass index (BMI): 20.4 ± 2.39 kg/m2; body fat: 16.8 ± 2.21%) participated. Measures of anthropometry used for body mass, body fat percentage (%BF), and BMI as well. Postural control, 15 m sprint, squat jumps and counter-movement jumps (SJ, CMJ), and T-half test for change-of-direction (CoD) were parameters of physical performance. The grade point average (GPA) of mathematics determined academic attainment. Moore's equations were used to estimate their maturity status (PHV). Biological maturation was highly correlated with most (not 15 m sprint) physical and academic performance parameters, especially CMJ (r = -0.812) and mathematics (r = -0.781). Academic performance showed the largest relations to the jumping performance (CMJ: r = 0.771; SJ: r = 0.723). In contrast, anthropometric and fatness parameters were not relevantly (r ≥ 0.5) correlated with any other parameters. The largest correlations were calculated for sitting height vs. SJ (r = -0.408), sitting height vs. postural control (r = -0.355), leg length vs. postural control (r = -0.339). As a result, it is essential to take biological maturation inconsideration while assessing the physical and academic achievement of young soccer players. In consequence, soccer coaches and physical education (PE) teachers should be cognizant of the impact of biological maturity on physical and academic performance to assist fair and equal opportunities for achievement in young players.

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).

Motor Coordination in Primary School Students: The Role of Age, Sex, and Physical Activity Participation in Turkey

Motor coordination (MC) is an essential skill underpinning precise and controlled movements, contributing significantly to daily functioning and overall performance. The developmental trajectory of MC in children is intricately shaped by a spectrum of factors encompassing age, gender, and physical activity engagement. Delving into the complex interrelation of these variables holds the potential to unravel nuanced developmental trends and offer targeted avenues for interventions aimed at augmenting motor proficiency in the pediatric population. This study aimed to assess the differences in MC of primary school students based on sex, age, and physical activity participation (PAP). A total of 848 students from public primary schools, aged between 6-9 years, including 412 boys and 436 girls. The MC was measured using Körperkoordinationstest für Kinder (KTK3+) test battery, which included Jumping sideways (JS), Balancing backward (BB), Moving sideways (MS), and Eye-Hand Coordination (EHC). One-way multivariate analysis of variance (MANOVA) was used to determine the binary and triple interactions of sex, age, and PAP variables on the MC parameters of the participants. The study revealed that boys aged 6-9 had higher scores than girls on eye-hand coordination (EHC) (p < 0.02). No significant gender-related differences in balancing backward (BB), jumping sideways (JS), and moving sideways (MS) were found. When the subtests of KTK3+ were compared by age, a significant difference was observed between the groups in all subtests (p < 0.05). With respect to PAP, students with PAP had a significant advantage in all subtests of the KTK3+ (p < 0.05). The double co-effects or triple co-effects of age, sex, and PAP parameters do not influence the KTK parameters. This study presents evidence supporting sex differences in the motor skills of children within this age range and highlights the potential impact of age and physical activity on motor development.

Maturity-Related Variations in Morphology, Body Composition, and Somatotype Features among Young Male Football Players

The study aimed to investigate differences in anthropometry, body composition (BC), and somatotype in young football players of the same chronological age according to the maturity stage. Overall, 64 elite players (age: 14.28 ± 0.46 years) were evaluated for standing and sitting body height, girth measures, and BC using the bioelectric impedance scale and skinfold thickness. In total, two-thirds (73.44%, n = 47) of football players were classified as on-time maturers, 12.50% (n = 8) were early maturing, and 14.06% (n = 9) were late maturing. Standing and sitting height, leg length, fat-free mass, and muscle mass were significantly different (p < 0.001) across maturity groups. A significant decrease (p < 0.05) with maturity progression was seen for subscapular and suprailiac skinfolds along with a girth increase at all sites (p < 0.05). Early maturers were balanced ectomorphs, while on-time and late maturers featured mesomorph-ectomorph characteristics. The obtained results suggested that mature players have better BC presented as a lower fat percentage along with higher muscle mass, advantages in circumferences, and longitudinal dimensions of the body with highlighted mesomorph features. Maturity can have a substantial influence on body measures, thereby affecting sport-specific performance. Early maturers can use their anthropometric advantages and compensate for a lack of talent, consequently preventing even participation of physically undeveloped players in training. A better understanding of maturity, BC, and somatotypes can help in the selection of young talented players.

Differences in body composition, static balance, field test performance, and academic achievement in 10–12-year-old soccer players

Introduction: This study aimed to compare 10–12-year-old Qatari male soccer players (n = 45) regarding different dimensions (anthropometric, academic and physical performance).

Methods: Anthropometric parameters (body mass, fat percentage (%BF), body mass index (BMI)) academic achievement (mathematics and science grade point average [GPA]) and physical performance [Yo-Yo Intermittent Recovery Test (level 1), squat jumps (SJ), counter-movement jumps (CMJ), stork balance test, 10 and 15 m sprint tests, T-half test for change-of-direction (CoD) ability, hand-grip strength, medicine ball throw (MBT)] were measured. Schoolchild soccer players were divided into three groups: 12-year-old players (U12; n = 16), 11-year-old players (U11; n = 14), 10-year-old players (U10; n = 15).

Results: Apart from mathematics, Yo-Yo IR1 and 10 m sprint, all performance parameters showed significant age effects. The largest age-related difference was observed for 15 m sprint (p &lt; 0.001). Both adjacent age groups displayed significant differences for 15 sprint (U10 vs. U11: p = 0.015; U11 vs. U12: p = 0.023). Concerning academic performance, a significant age effect was found for science (p &lt; 0.001). There was a main age effect on academic performance difference between U10 and U11 (p = 0.007). Academic parameters did not correlate with any physical performance parameter or anthropometric parameter. The strongest correlations were detected for body height and agility T-half test (r = −0.686) and medicine ball throw (r = 0.637). The biological maturity was strongly correlated with handgrip strength (r = −0.635).

Discussion: Soccer coaches and physical education teachers can use these data as reference values for evaluation of school-aged soccer players, and for ascertaining specific training targets. Obviously, short sprinting ability and aerobic capacity are not functions of age and need a specific training for significant improvements.

Gender- and Sport-specific Normative Anthropometric and Physical Values in Talent-Identified High School Athletes

ABSTRACT

Larkin, P, Sortino, B, Carlon, T, Saunders, T, and Pane, C. Gender- and sport-specific normative anthropometric and physical values in talent-identified high school athletes. J Strength Cond Res 37(3): 606-615, 2023-Youth sport is associated with the identification and promotion of athletes within talent development pathways, with anthropometric and physical performance measures being key assessment and monitoring tools. To adequately evaluate performance within a population, normative reference data are needed; however, currently, there is limited normative values of talent-identified youth athletes. The aim of the current study is to present normative values of talent-identified youth sport academy athletes in relation to gender, age, and sport. Over a 5-year period, a total of 794 talent-identified youth athletes who attended a specialized school sports academy were assessed using anthropometric (i.e., heigh,; body mass) and physical performance (i.e., vertical jump, 20-m sprint, Yo-Yo intermittent recovery test 1) measures. In total, 451 male and 343 female athletes (grade 7: 12-13 years; grade 8: 13-14 years; grade 9: 14-15 years; grade 10: 15-16 years) were tested annually. The result demonstrates that for each gender, as age increases, there is a general increase in anthropometric measures (i.e., height and body mass). Furthermore, with increasing age, athletes generally have a higher vertical jump, faster sprint performance, and improved physical endurance. The results highlight sport-specific differences for each measure. Overall, the results of the study provides age-, gender-, and sport-specific normative data of talent-identified youth athletes. These findings provide representative performance profiles of talent-identified high school athletes, with the values potentially being used by coaching staff (i.e., head coaches, strength and conditioning coaches, rehabilitation staff) for comparison purposes.

Change of Direction Performance and its Physical Determinants Among Young Basketball Male Players

The main aim of the present study was to examine the effects of the age group (U-15, U-17 and U-19) on change of direction (COD) performance and its specific physical determinants among young basketball male players. Thirty-one young male basketball players (13-18 years) volunteered to participate in this study. The sample was divided into 3 age groups (U-15, U-17, U-19). All the evaluations were carried out in the same order in 3 sessions as follows: 1) body composition, self-reported sexual maturation, COD performance, and intermittent endurance capacity; 2) reactive strength index (RSI), 15-m sprint, and repeated sprint ability (RSA) test; 3) vertical and horizontal jumps and lower-limb strength. The results showed significant differences between groups for age, sexual maturation, endurance capacity, horizontal and vertical jump performances, RSI, COD, RSA, and lower-limb strength (p < 0.05). Significant correlations were identified between COD performances and some physical determinants such as jumping ability and RSA performance (-0.43 < r < 0.85; p ≤ 0.05). In conclusion, there are age effects on COD performance and its specific physical determinants among young basketball male players. The associations between COD performance and its determinants should be considered by practitioners when programing athletic talent development for this population.

Associations between biological maturity level, match locomotion, and physical capacities in youth male soccer players

INTRODUCTION

Biological maturity level has shown to affect sport performance in youths. However, most previous studies have used noninvasive methods to estimate maturity level. Thus, the main aim of the present study was to investigate the association between skeletal age (SA) as a measure of biological maturation level, match locomotion, and physical capacity in male youth soccer players.

METHOD

Thirty-eight Norwegian players were followed during two consecutive seasons (U14 and U15). Match locomotion was assessed with GPS-tracking in matches. SA, assessed by x-ray, physical capacities (speed, strength and endurance) and anthropometrics were measured in the middle of each season. Analysis of associations between SA, match locomotion, and physical capacities were adjusted for the potential confounding effect of body height and weight.

RESULTS

In matches, positive associations were found between SA and maximal speed and running distance in the highest speed zones. Further, SA was associated with 40 m sprint time and countermovement jump (CMJ) height, and with intermittent-endurance capacity after adjusting for body height (U14). Associations between SA and leg strength and power, and between SA and absolute VO_2max were not significant after adjusting for body weight. There was no association between SA and total distance covered in matches.

CONCLUSION

Biological maturity level influence match locomotion and performance on physical capacity tests. It is important that players, parents and coaches are aware of the advantages more mature players have during puberty, and that less mature players also are given attention, appropriate training and match competition to ensure proper development.

Maturation Selection Biases and Relative Age Effect in Italian Soccer Players of Different Levels

Simple Summary

Soccer academies and societies research young players who are supposed to possess great motor skills. In association with these, adolescents who appear to be talented exhibit more developed anthropometric and body composition features than untalented players. Although many selected soccer players appear to present an earlier maturation than their contemporaries, it is not clear whether soccer teams of different competition levels are aware of this aspect and considered these discrepancies in the scouting selection process. In addition, it remains unclear if the biological maturity and relative effect are two interchangeable methods of evaluation and if one of them deserves to be preferred by the soccer scouters. This research aims to investigate the effect of the team level, maturity status and relative-age effect, and their interactions, on body characteristics, cellularity, and physical performance in adolescent soccer players. Despite the relative age effect remaining the easier analysis to consider, the evaluation of maturity status seems to be the most reliable method to detect better capabilities due to early growth.

Abstract

Soccer is a sport practiced all over the world, in which players are expected to show specific physical and technical skills. Soccer academies look for young talented individuals to develop promising players. Although several parameters could affect the players’ performance, the relative age effect (RAE) and the maturity status appeared debated. Therefore, this study compared the differences in RAE and biological maturity among the players of two Italian soccer teams of different levels and to understand their interaction effects with the competition level on youth players’ physical characteristics and abilities. One hundred and sixty-two young soccer players from the U12 to U15 age categories of the elite (n = 98) and non-elite (n = 64) teams were recruited. The prevalence of maturity status and RAE was observed. Many anthropometric parameters, BIA vectors, and motor tests (CMJ, Sprint, RSA) were carried out. The maturity status had a greater effect on several anthropometric characteristics and on 15 m sprint, while it affected the CMJ only in U12 (F = 6.187, p ≤ 0.01). Differently, the RAE seemed to priorly affect the U13 and U15 categories in body composition, whereas its effect appeared on the 15-m sprint (F_{(3, 45)} = 4.147, p ≤ 0.01) and the RSA (F_{(3, 45)} = 3.179, p ≤ 0.05) in the U14 category. In addition, early matured players or those who were born in the first six months presented cellular characteristics similar to adult elite players. Soccer professionals should be encouraged to monitor the maturity status to better interpret changes in the physical performance of young soccer players to guide adequate training plans.

Chinese physical fitness standard for campus football players: A pilot study of 765 children aged 9 to 11

Objectives: In 2022, 55 million Chinese children participate in campus football; however, there is no physical fitness standard, making it a priority task to enhance the current national program. This study aimed to explore a pilot method for the development of a reliable physical fitness standard. Methods: This study examined 765 male football players aged 9 to 11 in 2020 and 2022. The anthropometric and physical fitness assessments were conducted in accordance with the Chinese Football Association's field manuel. Physical fitness tests include sit and reach test, t test, 30 m run test, and vertical jump test. Physical fitness standard was modeled using the generalized additive models for location, scale, and shape (GAMLSS). Data were fitted with appropriate GAMLSS distributions and smoothing term. P-splines were applied to smooth the model's parameters using the default local maximum likelihood method and link functions. Following diagnostics of fitted models, age-specific centile estimations were computed for physical fitness tests. In addition, players in each age group were categorized according to their body mass index as normal weight or overweight/obese. Welch's t-test was utilized to compare the group differences in physical fitness testing. The significance level was chosen at p < 0.05. Results: Sit and reach test, t test, 30 m run test, and vertical jump test data were fitted with original Sinh-Arcsinh, Box-Cox power exponential, Box-Cox power exponential, and Box-Cox Cole and Green, respectively. Physical fitness standard for each age group is presented as tabulated centiles (1p, 3p, 5p, 15p, 25p, 50p, 75p, 85p, 95p, 97p, 99p). Overweight/obese campus football players did significantly worse (p < 0.05) on the t test, 30 m run test, and vertical jump test than their normal-weight peers of the same age. Conclusion: This study developed the first physical fitness standard for 9 to 11-year-old campus football players in China. We made three recommendations to Chinese policymakers on sample size, data management, and field procedure for the creation of a national physical fitness standard.

Is Motor Coordination the Key to Success in Youth Cycling?

PURPOSE

To evaluate the predictive value of a (non-)sport-specific test battery on the future success of young cyclists, test scores were compared with competition performances 2-3 years later.

METHODS

Three motor coordination, 5 physical performance, and 2 cycling-specific measurements were collected in 111 U15 (13.0-14.9 y) and 67 U17 (15.0-16.9 y) male road cyclists. In addition, maturity status, relative age, and competition history were assessed. National and provincial competition results 2-3 years later, in the U17year2 and U19year2 categories, were submitted to 2 separate 4-stage hierarchical regressions.

RESULTS

The results of the model of the U15 group revealed that maturity, relative age, competition history, motor coordination, physical performance, and cycling-specific performance accounted for 22.6% of the variance in competitive success. For the U15 category, only maturity and motor coordination were significant predictors of competitive success in the U17year2 category. Maturity and motor coordination each uniquely explained ±5% of the variance. However, for the U17 group-neither motor coordination, physical performance, nor cycling-specific performance could predict competitive success in the U19year2 category.

CONCLUSIONS

The current study underlines the importance of general motor coordination as a building block necessary for optimal development in youth cycling. However, considering the lack of predictive value from the U17 category onward, other features may determine further development of youth athletes. Nevertheless, it is questioned why athletes need to possess a minimum level of all physical, motor coordination, and cycling-specific characteristics to experience success and enjoyment in their sport.

Physical characteristics of elite youth male football players aged 13-15 are based upon biological maturity

Background

Older and more mature football players have been reported to gain advantages in the selection process during adolescence. The aim of this study was to investigate the influence of skeletal age (SA) on the physical characteristics of elite male football players aged 13-15 years through a cross-sectional study.

Methods and Materials

We enrolled 167 elite players aged 13-15 from three academic football schools in China, and measured height, body mass, thigh circumference, skinfold (triceps and calf), 10 m/30-m sprint, T-tests (left and right), 5 × 25-m repeated-sprint ability (5 × 25 RSA), standing long jump, and YoYo intermittent recovery test level 1 (YYIR1). Subjects were divided into early-, average-, and late-maturity levels according to their SA and chronological age (CA) based on the following criteria: SA-CA > +1 year, SA-CA = ±1 year, and SA-CA < -1 year, respectively. The differences in parameters among the groups were analyzed using one-way analysis of variance and Bonferroni's post-hoc test, with statistical significance set at p < 0.05.

Results

Relative to the late-maturing players, the early- and average-maturing players aged 13-15 years were taller, heavier, had a larger thigh circumference, and scored higher on the standing long jump, 30 m sprint, and 5 × 25-RSA (p < 0.05). The physical (except for body-fat percentage) and athletic characteristics of players aged 13-15 were not only significantly influenced by biological maturity, but also increased significantly with CA. The influence of biological maturity on height, 30-m sprints, and 5 × 25-m RSA diminished with age and exerted no significant effect on body-fat percentage and on YYIR1. Late-maturing players exhibited the greatest increase in physical (except for body-fat percentage) and athletic performance (except for the 10-m sprint) compared to players of early and/or average maturity.

Conclusions

Although early-maturing players aged 13-15 possessed better anthropometric and physical performance than late- and average-maturing players, the growth and development of physical function of late- and average-maturing players was significantly greater, particularly with respect to height, sprint speed, and muscular power.

Participation of Soccer Training Improves Lower Limb Coordination and Decreases Motor Lateralization

Athletes, who display less lateralization, are considered to be more successful in their sports. Therefore, it is important to test the lateralization profiles of the athletes to determine future prospects. Soccer is one of the sports where lateralization plays an important role because performing the passes and kicks with either foot may increase the success rate. Improved lower limb coordination is also very essential to perform the soccer skills more efficiently. Thus, the purpose of this study was to investigate the motor lateralization profiles of youth soccer players and to compare the same lateralization to non-athletes. A total of 28 healthy youth (14 soccer players) aged between 14 and 16 years voluntarily participated in this study. All participants were right-footed and were asked to hit the targets with their either foot maintaining accuracy in a custom-made virtual reality interface. Final position error (FPE) and foot path deviation from linearity (FPDL) were calculated to test motor lateralization for each foot and group. Two-way Mixed Model ANOVA was conducted for each dependent variable. Results indicated significant differences for FPDL between groups, while there were no significant differences between groups and within feet for FPE. Nonathletes had significantly higher FPDL with their nondominant foot compared to their dominant foot, which was not observed among soccer players. Overall, nonathletes' movements were more curvature path compared to soccer players, thus, can be considered as less coordinated. As soccer players did not show a difference between their feet on FPDL and performed better than nonathletes, soccer participation can improve lower limb coordination as well as alter motor performance and lateralization.

Fundamental movement skills and perceived competence, but not fitness, are the key factors associated with technical skill performance in boys who play grassroots soccer

OBJECTIVE

This study examined the association between fitness, fundamental movement skills (FMS) and perceived competence on technical skills in boys engaged in grassroots soccer. Methods: Sixty boys (8-12 years of age, Mean ± SD = 10 ± 1 years) undertook assessment of FMS, perceived competence, physical fitness (15m sprint speed, standing long jump distance and seated 1kg medicine ball throw as a composite z-score) and technical skills (dribbling, passing and shooting as a composite z-score).

RESULTS

Multiple backwards linear regression was used to determine to amount of variance in technical skill explained by FMS, perceived competence and fitness. Results indicated a significant model (F 3,58= 42.04, P = .0001, Adj R2 = .680) which explained 68% of the variance in technical skills. Perceived competence (β=.316, P =.001), Total FMS (β=.140, P =.002), and chronological age (β=.863), P =.001) significantly contributed to the model.

CONCLUSION

This study demonstrates that better technical skills (passing, dribbling, shooting) in youth soccer are explained, alongside age, by being competent in FMS and having a more positive perception of competence. Coaches should therefore seek to encourage development of these factors during childhood for the benefit of technical skill performance.

Influence of biological maturation status on selected anthropometric and physical fitness variables in adolescent male volleyball players

Background

The identification of sport talent among adolescent athletes is a topic that in recent years has been a major focus of interest for both the scientific community and sport managers. Both anthropometry and physical performance through fitness tests have demonstrated to be key elements. Biological maturation, due to its influence on anthropometric variables and physical fitness, has also been studied in relation to sport talent identification.

Objective

To analyse differences according to biological maturation status in anthropometric characteristics and performance in physical fitness tests, and to determine which variables predict better performance in physical fitness tests in adolescent volleyball players.

Methods

A cross-sectional design was followed to collect the data. A total of 48 male sub-elite volleyball players (14.17 ± 0.73 years) completed a socio-demographic and sports ad hoc questionnaire. Anthropometric variables were measured following the guidelines of the International Society for the Advancement in Kinanthropometry (ISAK) including four basic measurements (body mass, height, sitting height and arm span); eight skinfolds (triceps, biceps, subscapular, iliac crest, supraspinale, abdominal, thigh and calf); four girths (arm relaxed, flexed and tensed arm, middle thigh and calf); five breadths (biacromial, biileocrestal, humerus, femur and bi-styloid); three lengths (acromiale-radiale, radiale-stylion and stylion-medio dactilion); and a height (ilioespinale). Physical fitness was assessed, including the sit-and-reach, back scratch, long jump, medicine ball throw, counter movement jump (CMJ), 20 meters sprint, and agility tests. Furthermore, maturity offset and age at peak height velocity (APHV) was calculated.

Results

Significant differences were found in the body mass (Mean Difference, MD = 20.86-30.75), height (MD = 11.72-19.09), sitting height (MD = 4.27-10.27), arm span (MD = 12.91-20.78), body mass index (MD = 3.72-5.63), upper limb length (MD = 7.76), corrected muscle girths (MD = 2.06-9.31), ∑6 and 8 skinfolds (MD = 3.67-50.21) fat mass and percentage (MD = 0.30-11.58), muscle (MD = 4.13-10.64) and bone mass (MD = 1.61-3.54) (p < 0.001-0.030), showing higher values the early maturers. In the physical fitness tests, significant differences were observed in the medicine ball throw (MD = 1.26-2.80) and in CMJ power (MD = 156.71-379.85) (p < 0.001). Regression models identified fat mass percentage predicted worse physical test performance (p < 0.001), while age, maturation offset, muscle and bone variables were predictors of better physical performance (p < 0.001).

Conclusions

Significant differences based upon the stages of biological maturation were found in the anthropometric and physical condition variables in favor of the players whose maturation process was more advanced, with the variables related to fat and adipose, muscle and bone development conditioning their performance in the physical condition tests.

Fundamental Movement Skills and Physical Fitness Are Key Correlates of Tactical Soccer Skill in Grassroots Soccer Players Aged 8–14 Years

One hundred and twenty-one children (58 boys and 63 girls) aged 8–14 years (mean ± SD = 12 ± 1 years) who were regularly engaged in grassroots soccer participated in this study. Participants undertook assessments of fundamental movement skill (FMS) using the Test of Gross Motor Development-3, perceived ability using the Perceived Physical Ability Scale for Children, physical fitness via 15-m sprint time, standing long jump distance, and technical skill using the university of Ghent dribbling test. The Procedural Tactical Knowledge Test was employed as a measure of tactical skill from which metrics for positioning and movement and recognizing spaces were derived. Maturation was determined from anthropometric measures. Analysis of covariance examined gender differences in tactical skills accounting for FMS, fitness, perceived ability, technical skill, maturation, and age. Results indicated no significant differences in tactical skills between boys and girls (p > .05). For recognizing spaces, 56% of the variance was explained with FMS (p = .001), physical fitness (p = .02), and technical skill (p = .02) contributing to the model. For positioning and movement, a significant model explained 55% of the variance in this element of tactical behavior with FMS (p = .002) and technical skill (p = .02) significantly contributing to the model.

Skill assessments in youth soccer: A scoping review

Talent identification in youth soccer is a complex decision-making process that requires selectors to judge an individual's future potential. While there has been considerable research into the performance characteristics of talented players, investigators have limited consensus on the best approach to assess soccer skills. Most of the research explains why we should measure skill instead of how we go about assessing skill. Therefore, the current scoping review aimed to synthesize and analyse skill assessments in youth soccer. Four electronic databases (EBSCO, ProQuest, PubMed, and Scopus) were searched for relevant studies. Information regarding the sample characteristics and methodological design of the skill assessments were extracted, synthesised, and presented in a qualitative analysis. Overall, 226 skill assessments were used across the 93 included studies. Male players from different ages (U/7-U/23) and playing levels comprised most (89%) of the collective sample. The majority of assessments were performed in settings not representative of football match-play (68%), focused on offensive skills (99%), and included skill outcome measures (95%). The variability of assessments highlights some confusion about the best way to assess soccer skill, potentially limiting selectors ability to identify skilful players. Ultimately, this will impact the number of quality players within the talent pool.

Test–Retest Reliability of Soccer Dribbling Tests in Children

The present study examined the test–retest reliability of the Ghent University dribbling test and short dribble test in a pediatric population. Fifty-four boys aged 9–14 years (mean ± SD = 11 ± 2 years) undertook the Ghent University and dribbling tests on two occasions separated by 2 weeks. Intraclass correlation coefficients, coefficient of variation, and 95% limits of agreement were conducted for each test. Intraclass correlation coefficients and coefficient of variation indicated good to excellent reliability, and relatively small variability for both dribbling tests. The 95% limits of agreement indicated relatively little bias Ghent University dribbling test for both running alone and running with the ball components, and the Bangsbo and Mohr short dribble test. The results of the present study suggest both dribbling tests examined in the present study demonstrate good reliability and low levels of systematic bias.

Does motor coordination influence perceptual-cognitive and physical factors of agility in young soccer players in a sport-specific agility task?

This study aims to determine whether motor coordination influences the perception-decision time (perceptual-cognitive factor) and movement response time (physical factor) of young soccer players in a sport-specific agility task regardless of maturation. Eighty-seven young male soccer players were analysed. Anthropometric measurements were used to determine the maturity offset, while physical qualities including agility, change of direction speed (CODS) and motor coordination were also assessed. The following variables were obtained from these tests: Motor coordination score, perception-decision time, movement response time, agility time and CODS time. Motor coordination revealed a non-significant correlation with perception-decision time (r = 0.10, p = 0.34). However, motor coordination showed negative and significant correlations with CODS time (r = -0.47, p < 0.01), agility time (r = -0.52, p < 0.01) and movement response time (r = -0.62, p < 0.01). In addition, regression analysis showed that each increase in motor coordination score was associated with significant decreases in agility time (b = -0.023), movement response time (b = -0.021) and CODS time (b = -0.021) independent of maturity offset. The results of this study indicated that motor coordination was significantly related to the physical factors of agility in young soccer players.

The Effects of Age, Biological Maturation and Sex on the Development of Executive Functions in Adolescents

The development of executive functions (EF) has been widely investigated and is associated with various domains of expertise, such as academic achievement and sports performance. Multiple factors are assumed to influence the development of EF, among them biological maturation. Currently the effect of biological maturation on EF performance is largely unexplored, in contrast to other domains like physical development or sports performance. Therefore, this study aimed (a) to explore the effect of chronological age on EF performance and (b) to investigate to what extent age-related changes found in EF are affected by biological maturation on both sexes. To this end, EF performance and degree of maturity, indexed by percentage of predicted adult height (%PAH), of 90 adolescents (11-16 years old, 54% males) were measured on three occasions in a time frame of 12 months. A Generalized Estimating Equation (GEE) approach was used to examine the association between chronological age and %PAH and the weighted sum scores for each EF component (i.e., inhibition, planning, working memory, shifting). All models were run separately for both sexes. The males' results indicated that EF performance improved with age and degree of maturity on all four components. Interaction effects between age and %PAH on inhibition showed that at a younger age, males with a higher %PAH had a lower chance of performing well on inhibition, whereas at later ages, males with a higher %PAH had a higher chance to have a good inhibition performance. For working memory, it seems that there is no maturity effect at a younger age, while at later ages, a disadvantage for later maturing peers compared to on-time and earlier maturing male adolescents emerged. Females showed slightly different results. Here, age positively influenced EF performance, whereas maturity only influenced inhibition. Interaction effects emerged for working memory only, with opposite results from the males. At younger ages, females with lower %PAH values seem to be scoring higher, whereas at later ages, no maturity effect is observed. This study is one of the first to investigate the effect of biological maturation on EF performance, and shows that distinct components of EF are influenced by maturational status, although the effects are different in both sexes. Further research is warranted to unravel the implications for maturation-driven effects on EF that might significantly affect domains of human functioning like academic achievement and social development.

Age-related differences in linear sprint in adolescent female soccer players

BACKGROUND

Several studies have observed the contribution of chronological age, biological maturation, and anthropometric characteristics to sprinting performance in young soccer players. Nevertheless, there are no studies that have analysed the contribution of these characteristics to running speed qualities in adolescent female soccer players.

OBJECTIVE

This study investigated age-related differences in sprint performance in adolescent female soccer players. Also, it examined the possible influence of anthropometry [body mass and body mass index (BMI)] and biological maturation [age at peak height velocity (APHV)] in sprint performance.

METHODS

Eighty adolescent female soccer players [under (U) 14, n = 20; U16, n = 37; U18, n = 23] participated in this study. Players were tested for 40 m sprint (each 10 m split times).

RESULTS

Posthoc analysis revealed better performance in all split sprint times of older soccer players (U18 and U16) compared with younger category (F: 3.380 to 6.169; p < 0.05; ES: 0.64 to 1.33). On the contrary in all split sprint times, there were no significant changes between U16 and U18 (p < 0.05; ES: 0.03 to 0.17). ANCOVA revealed differences in all parameters between groups, controlled for APHV (p < 0.05). In contrast, all between-group differences disappeared after body mass and BMI adjustment (p > 0.05). Finally, the results indicate that BMI and body mass were significantly correlated with 40 m sprint (p < 0.05; r: -0.31) and 20 m flying (p < 0.01; r: 0.38), respectively.

CONCLUSION

In the present players' sample, body mass and BMI had a significant impact on running speed qualities.

Screening Youth Soccer Players by Means of Cognitive Function and Agility Testing

Talent identification in sports is a heavily debated topic. Previous studies have separately explored either executive functions or gross motor skills to predict the success of top-level soccer players or, more generally, to characterize elite performance in soccer. However, at mid-childhood, the possibility to scope sport-specific requirements remains elusive. We aimed in this study to investigate a valid and simple method of testing for a unique combination of cognitive and speed abilities for identifying promising soccer players at mid-childhood. We measured cognitive functions by means of a Stroop smartphone application and agility with a T-Drill Ball-success test, in two groups of (a) elite- (n = 31) and (b) low-division (n = 37) Italian 7-year-old male soccer players. We administered the tests in a randomized order to both groups. We found better inhibitory control, cognitive flexibility and soccer-specific agility in high-division versus low-division players (p < .001). Inhibitory response and agility were positively associated with the augmented quality of the performance from low-division players to high-division players (r = .55; p = .0001). These results suggest that, even at an early age, cognitive control together with soccer-specific skills is associated with better performance.

Actual and perceived motor competence mediate the relationship between physical fitness and technical skill performance in young soccer players

This study examined the role of fundamental movement skills (FMS) and perceived competence in the relationship between physical fitness and technical soccer skills in children. Seventy boys aged 7-12 years of age (Mean ± SD = 9 ± 2 years) who were regularly engaged in grassroots soccer participated in the present study. The Test of Gross Motor Development-2 (Ulrich, 2001) was used to assess FMS and the Perceived Physical Ability Scale for Children (Colella, et al., 2008) was used to assess perceived competence. Technical skill was determined from three tests reflecting dribbling, passing and shooting. Z-scores of each measure were summed, creating a composite measure of technical skill. Three measures of physical fitness were employed; 15m sprint time, standing long jump, and seated medicine ball (1kg) throw. Z-scores for each measure were summed creating a composite measure of physical fitness. The relationship between technical skill and FMS, fitness, perceived competence and age was examined via path analysis. Results indicated two significant mediated pathways: from physical fitness to technical skills via FMS, and from physical fitness to technical skills via perceived competence. Once these mediators had been accounted for, there was no direct link from physical fitness to technical skills. Coaches should therefore seek to avoid one-sided delivery of practice by not solely focusing on football type drills, and focusing on a range of activities which enhance a broad foundation of FMS and promote strategies to positively influence a child's perception of their own competence.

Differences in Maturity and Anthropometric and Morphological Characteristics among Young Male Basketball and Soccer Players and Non-Players

Background: An aspect that influences sport performance is maturation status, since, within the same chronological age group, boys who have advanced maturation outperform their late maturing peers in tests of muscular strength, power, and endurance. Therefore, the aims of the present study were: (i) to investigate the differences in biological maturation and anthropometric and morphological characteristics among three groups of Italian adolescents, two of which were sportive (practicing basketball and football) and one non-sportive, and (ii) to identify the anthropometric and morphological predictors that best discriminate these three groups. Methods: Sixty-one basketball and 62 soccer players and 68 non-sportive youths were measured (mean age = 13.0 ± 1.1 y). Anthropometric characteristics were taken and body mass index, cormic index, body composition parameters, and somatotype were derived. An estimation of maturity status was carried out considering the years from peak height velocity (PHV). Two-way 3 × 3 ANOVAs was performed on all anthropometric characteristics to test the differences within sport groups and maturity status groups. Discriminant function analysis (stepwise criteria) was then applied to anthropometric and body composition variables to classify subjects into the three different sport categories. Results: Differences in anthropometric characteristics were detected among the three groups. For somatotype, differences among all of the considered groups were higher for endomorphy (p < 0.001; effect size = 0.13). Biological maturity influences the differences in the anthropometric characteristics and body composition among subjects of the same chronological age during adolescence. The variables that best discriminated the three groups were represented by body composition parameters, body proportions, and body build. Conclusions: This study confirms that boys who practice sport present healthier body composition parameters, with lower level of fat parameters. The assessment of maturity status is a fundamental factor in explaining anthropometric and body composition differences among peers in this period. Its comprehension may assist coaches and technical staff in optimizing competitive efficiency and monitoring the success of training regimes.

Associations Between Variations in Accumulated Workload and Physiological Variables in Young Male Soccer Players Over the Course of a Season

This study sought to analyze the relationship between in-season training workload with changes in aerobic power (VO_{2m ax} ), maximum and resting heart rate (HR _max and HR _rest ), linear sprint medium (LSM), and short test (LSS), in soccer players younger than 16 years (under-16 soccer players). We additionally aimed to explain changes in fitness levels during the in-season through regression models, considering accumulated load, baseline levels, and peak height velocity (PHV) as predictors. Twenty-three male sub-elite soccer players aged 15.5 ± 0.2 years (PHV: 13.6 ± 0.4 years; body height: 172.7 ± 4.2 cm; body mass: 61.3 ± 5.6 kg; body fat: 13.7% ± 3.9%; VO_{2m ax} : 48.4 ± 2.6 mL⋅kg^-1⋅min^-1), were tested three times across the season (i.e., early-season (EaS), mid-season (MiS), and end-season (EnS) for VO_{2m ax} , HR _max , LSM, and LSS. Aerobic and speed variables gradually improved over the season and had a strong association with PHV. Moreover, the HR _max demonstrated improvements from EaS to EnS; however, this was more evident in the intermediate period (from EaS to MiS) and had a strong association with VO_{2m ax} . Regression analysis showed significant predictions for VO_{2m ax} [F _{( 2, 20)} = 8.18, p ≤ 0.001] with an R ² of 0.45. In conclusion, the meaningful variation of youth players' fitness levels can be observed across the season, and such changes can be partially explained by the load imposed.

Analysis of Fitness Status Variations of Under-16 Soccer Players Over a Season and Their Relationships With Maturational Status and Training Load

The purposes of this study were (i) to analyze the variations in maximal oxygen consumption (VO_2max), maximal heart rate (HR_max), heart rate at rest, acceleration, maximal speed, agility, anaerobic sprint test (RAST) of peak power (RPP), RAST of minimum power, RAST of average power (RAP), and RAST of fatigue index (RFI) during the competitive season, using maturation status and accumulated training load as covariates, and (ii) to describe the differences between responders and non-responders in relation to baseline levels. Twenty-three elite players from the same team competing in the national under-16 competitions were evaluated for 20 weeks in period 1 (before league), middle (mid league), and period 2 (after league). The VO_2max (p = 0.009), maximal speed (p = 0.001), RPP (p < 0.001), RAP (p < 0.001), and RFI (p < 0.001) significantly changed across the assessment periods. Interestingly, using accumulated training load and maturation status as covariates revealed no statistical significance (p > 0.05). When analyzing responders and non-responders, only HR_max (between periods 1 and 2) showed no differences between the groups. As a conclusion, it can be seen that accumulated training load and maturation status play an important role in the differences observed across the season. Thus, coaches should consider the importance of these two factors to carefully interpret fitness changes in their players and possibly adjust training decisions according to the maturation level of the players.

Accuracy of maturity prediction equations in individual elite male football players

BACKGROUND

Equations predicting age at peak height velocity (APHV) are often used to assess somatic maturity and to adjust training load accordingly. However, information on the intra-individual accuracy of APHV in youth athletes is not available.

AIM

The purpose of this study is to assess the accuracy of predication equations for the estimation of APHV in individual youth male football players.

SUBJECTS AND METHODS

Body dimensions were measured at least every three months in 17 elite youth male football players (11.9 ± 0.8 years at baseline) from the 2008-2009 through the 2011-2012 seasons. APHV was predicted at each observation with four suggested equations. Predicted APHV was compared to the player's observed APHV using one-sample-t-tests and equivalence-tests. Longitudinal stability was assessed by comparing the linear coefficient of the deviation to zero.

RESULTS

Predicted APHV was equivalent to the observed APHV in none of the players. A difference with a large effect size (Cohen's d > 0.8) was noted in 87% of the predictions. Moreover, predictions were not stable over time in 71% of the cases.

CONCLUSIONS

None of the evaluated prediction equations is accurate for estimating APHV in individual players nor are predictions stable over time, which limits their utility for adjusting training programmes.

Change of direction asymmetry across different age categories in youth soccer

Background

In youth, the development of change of direction (COD) and sprint performance is a key component for successfully competing in soccer across age. During a COD, the presence of directional asymmetries may be detrimental due to the unpredictable nature of the sport. Therefore, the aims of the study were to investigate asymmetries in COD ability and to examine the differences in COD and sprint performance across age in young soccer players.

Methods

Sixty-eight sub-elite soccer players of different age categories (U18, U17, U16, U15) were tested on a 10-m linear sprint test and 90°COD (5-m entry and exit) test in both directions. Asymmetric index (AI) of COD deficit was obtained for dominant (fastest) and non-dominant directions (slowest).

Results

The results showed that U16 were more asymmetrical than U18, U17, and U15 from large to moderate effects. The sprint time improved linearly across age with U18 and U15 displaying the fastest and slowest 10-m sprint performance (p < 0.01), respectively. Moreover, COD ability measured by COD deficit did not change across age (p > 0.05).

Conclusion

Given the results of this study, practitioners are encouraged to assess asymmetries between dominant and non-dominant directions rather than solely players’ COD ability in young soccer players.

Differences in physical fitness after an 8-week preseason training among elite football players aged 17-19 years

There may be an optimal period of time to maximize the improvement of physical fitness during adolescence. The aim of this study was to examine the magnitude of changes in physical fitness after 8 weeks of preseason training according to chronological ages after the age at peak high velocity. Thirty male young football players from an elite football team (U-16, n=10; U-17, n=10; U-18, n=10) participated in the study. The players completed an 8-week general preseason football training and participated in the pre- and posttests to measure physical fitness. The 8-week preseason training improved the power of all young players (P<0.05). The 20-m sprint performance was improved by training in U-16 and U-18 (P<0.05), but no changes were found in the U-17 group (P>0.05). Significant differences were found in the arrowhead left in U-16 and U-18 (P<0.05) after training; however, no difference was observed in U-17 (P>0.05). Coordination was enhanced further in U-16 and U-17 (P<0.05) compared with that in U-18 (P>0.05). The performance of repeated sprints and Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1) were similar between pre- and posttraining in all age groups (P>0.05). Collectively, the results emphasized the importance of systematic and scientific training methods to improve the fitness levels of young football players in the preseason training period. Moreover, training to improve coordination in young football players is effective at younger ages.

The Effectiveness of Biological Maturation and Lean Mass in Relation to Muscle Strength Performance in Elite Young Athletes

This study aimed to identify the interactional relationships between maturation (biological age (BA)) and lean mass on strength development in young athletes from different sports. Using a cross-sectional study design, a sample of 64 young athletes (rowers, swimmers, jiu-jitsu, volleyball, soccer and tennis players) of both sexes (13.6 ± 1.17 years) were recruited. Body composition was assessed using dual energy bone densitometry with X-ray source (DEXA). Strength of upper limbs (ULS), force hand grip (HG), vertical jump (VJ) and jump against movement (CMJ) were recorded. BA was estimated from anthropometrics. BA relationships were identified with upper limb strength in all athletes, and with the lower limb strength of tennis players, only (p < 0.05). An interaction effect between lean mass and BA was found (η2p = 0.753), as was a local effect within the regression models (ƒ2 ≥ 0.33). Athletes with a higher concentration of lean mass had superior upper and lower limb strength (p < 0.05). Lean mass showed a local effect (ƒ2) greater than that associated with BA. Although maturation is related to strength development, the strength of the relationship is mitigated by the accrual of lean mass. Specifically, the local effect of lean mass on muscle strength is broader than that of maturation, especially for lower limb strength.

Phase Angle from Bioelectric Impedance and Maturity-Related Factors in Adolescent Athletes: A Systematic Review

Phase angle (PhA) is a body composition (BC) parameter from bioelectrical impedance analysis that is suggested as a marker of cell integrity and general health. In adolescent athletes, PhA values are used to monitor the effects of training and competitions and seem to vary according to age, having an upward trajectory during puberty. Since adolescence is a period composed of maturation stages, the aim of this systematic review was to investigate the relationship between PhA and maturation stage in adolescent athletes. A search was conducted in PubMed/MEDLINE, BVS, Web of Science (WOS), Scopus, Science Direct, and Academic Search Complete (EBSCO) databases up to May 2020. Eligibility criteria followed the PICOS strategy and studies with healthy athletes aged 10–19 years of any level of competition were included. Six cross-sectional studies and two longitudinal studies met the inclusion criteria. Results showed that early and mature athletes have higher PhA than those who are non-matured or maturated late. Thus, PhA is influenced by the pubertal status. Considering BC is one of the factors influencing sports performance together with its growth-related changes, practitioners may use PhA values in BC analysis of adolescent athletes.

The effect of biological maturity status on ground reaction force production during sprinting

Sprint ability develops nonlinearly across childhood and adolescence. However, the underpinning ground reaction force (GRF) production is not fully understood. This study aimed to uncover the kinetic factors that explain these maturation-related sprint performance differences in Japanese boys and girls. A total of 153 untrained schoolchildren (80 boys, 73 girls) performed two 50-m maximal effort sprints over a 52-force-platform system embedded in an indoor track. Maturity offset (years from peak height velocity; PHV) was estimated using anthropometric data and used to categorise the children into six-year-long maturation groups (from group 1 [5.5-4.5 years before PHV] to group 6 [0.5 years before to 0.5 years after PHV). Maximum and mean step-averaged velocities across 26 steps were compared across consecutive maturation groups, with further GRF analysis (means and waveforms [statistical parametric mapping]) performed when velocity differences were observed. For boys, higher maximum velocities (effect size ± 90% CI = 1.63 ± 0.69) were observed in maturation group 2 (4.5-3.5 years before PHV) compared to group 1 (5.5-4.5 years before PHV), primarily attributable to higher antero-posterior GRFs across shorter ground contacts. Maximum velocities increased from maturation group 4 (2.5-1.5 years before PHV) to group 5 (1.5-0.5 years before PHV) in the girls (effect size ± 90% CI = 1.00 ± 0.78), due to longer ground contacts rather than higher GRFs per se. Waveform analyses revealed more effective reversal of braking forces and higher propulsive forces (e.g. 14%-77% of stance 4), particularly for comparisons involving boys, which suggested potentially enhanced stretch-shortening ability. Youth sport practitioners should consider these maturation-specific alterations when evaluating young athletes' sprint abilities.

Reliability of Change of Direction and Agility Assessments in Youth Soccer Players

Considering the vast physical and neural developments experienced throughout adolescence, the reliability of physical performance may vary in youth populations. This study aimed to examine the reliability of change of direction (COD) and agility tests in youth soccer players. Altogether, 86 youth soccer players, aged 13.6 ± 2.0 years, volunteered to participate. Data were collected from a modified 505 COD test (m505COD) and the Y-sprint drill in both pre-planned (Y-SprintPRE) and reactive (Y-SprintREACT) conditions during 2 sessions, 7 days apart. Anthropometric data including body mass, standing stature, and sitting height were also collected. COD and agility tests demonstrated good reliability (ICC = 0.81-0.91; CV = 1.2-2.0; d = 0.00-0.31; p < 0.01) for our entire sample. However, we observed a small negative relationship between age and intersession differences for the Y-SprintPRE (r = -0.28; p = 0.04), and moderate negative relationships between both age (r = -0.41; p < 0.01), and maturity offset (r = -0.39; p < 0.01) for the Y-SprintREACT. Although the COD and agility tests adopted within this study possess good intersession reliability, we observed greater intersession differences for younger and less mature individuals. We suggest that while COD and agility tests may provide meaningful objective data for monitoring the development of youth soccer players, these tests should be used with caution when evaluating younger, more immature athletes.

Maturity Related Differences in Body Composition Assessed by Classic and Specific Bioimpedance Vector Analysis among Male Elite Youth Soccer Players

The aim of this study was to analyze the efficiency of classic and specific bioelectrical impedance vector analysis (BIVA) in the assessment of maturity related differences in body composition among male elite youth soccer players, and to provide bioelectrical impedance reference data for this category. A group of 178 players (aged 12.1 ± 1.6 years) were registered in a professional Italian soccer team participating in the first division (Serie A). They were divided into three groups according to their maturity status while bioelectrical resistance and reactance were obtained. The classic and specific BIVA procedures were applied, which correct bioelectrical values for body height and body geometry, respectively. Percentage of fat mass (FM%) and total body water (TBW (L)) were estimated from bioelectrical values. Age-specific z-scores of the predicted age at peak height velocity identified 29 players as earlier-, 126 as on time-, and 23 as later-maturing. TBW was higher (p < 0.01) in adolescents classified as “early” maturity status compared to the other two groups and classic BIVA confirmed these results. Conversely, no differences in FM% were found among the groups. Specific vector length showed a higher correlation (r = 0.748) with FM% compared with the classic approach (r = 0.493). Classic vector length showed a stronger association (r = −0.955) with TBW compared with specific (r = −0.263). Specific BIVA turns out to be accurate for the analysis of FM% in athletes, while classic BIVA shows to be a valid approach to evaluate TBW. An original data set of bioelectric impedance reference values of male elite youth soccer players was provided.

Field-Based Tests for the Assessment of Physical Fitness in Children and Adolescents Practicing Sport: A Systematic Review within the ESA Program

High levels of physical fitness (PF) can positively affect both health and cognitive function, thus monitoring its levels in youth can help increase health and quality of life in adult populations later on. This systematic review aims to identify PF field-based tests used in young European populations practicing sport to find tools that are adequate for the considered target involving a new battery within the Enriched Sport Activities (ESA) project. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was followed. In the 83 identified articles, the main tests used were: vertical/horizontal jumps (for muscular strength/power); push-ups, running at maximum effort, sit-ups (for muscular strength/endurance); multistage non-intermittent and intermittent tests (for aerobic endurance); sit and reach (for flexibility); sprinting and agility T-tests (for speed and agility, respectively); 10 × 5 m shuttle run (SR) (for both speed and agility). Few studies assessed coordination, reaction time, power, and balance. Although the selected tests are widely used and validated, they do not determine all PF aspects and do not reflect sport-specific features. A final decision was made for the inclusion of the following tests: standing broad jump, seated medicine ball throw, 20 m SR test, 30 m sprint, Illinois test, and a new test, i.e., the crunning test, to assess different skill-related components at once. The use of this combination of tests allows for the assessment of all PF components and can help planning effective training programs and cultivate sporting talent.

Relative Age Effect on Youth Female Volleyball Players: A Pilot Study on Its Prevalence and Relationship With Anthropometric and Physiological Characteristics

The relative age effect (RAE) on human performance has been well studied in many sports, especially in soccer; however, little information has been available about the prevalence of RAE in volleyball, and its role on anthropometric and physiological characteristics. The aim of the present study was to examine (a) the prevalence of RAE in selected (i.e., to be considered for the national team) and non-selected youth female volleyball players, and (b) the relationship of birth quarter (BQ) with anthropometric and physiological characteristics. Selected (n = 72, age 13.3 ± 0.7 years, weight 62.0 ± 7.2 kg, height 1.72 ± 0.06 m) and non-selected female volleyball players (n = 53, age 13.9 ± 1.1 years, weight 56.4 ± 7.3 kg, height 1.66 ± 0.06 m) performed a series of anthropometric and physiological tests. Twenty-six selected participants were born in the first quarter of the year, 19 in the second, 14 in the third, and 13 in the forth. The corresponding frequency by BQ in non-selected participants was 12, 12, 17, and 12. No association was observed between the number of participants and their frequency by BQ neither in the selected (χ 2 = 2.79, p = 0.425) nor in the non-selected group (χ 2 = 0.64, p = 0.886). Anthropometric and physiological characteristics did not vary by BQ (p > 0.05). The absence of RAE in female volleyball players and the similarities of anthropometric and physiological characteristics among BQ might be due to technical-tactical character of this sport. These findings would be of great practical value for coaches and fitness trainers working with young volleyball players.

The Role of Somatic Maturation on Bioimpedance Patterns and Body Composition in Male Elite Youth Soccer Players

The purpose of this study was to examine the influence of chronological age (CA) and somatic maturation on body composition (BC) and bioimpedance parameters in male elite soccer players. BC and bioimpedance variables were measured in a sample of 249 players aged 9-18 years of age and registered in two professional Italian soccer teams. Results from segmental analysis showed transition time points where the influence of CA and somatic maturation on bioimpedance patterns and BC characteristics increased or subsided. The accelerated phases were assessed for fat free mass, total body water, and upper muscle area, with a starting time point at approximately -2.00 years from peak at velocity (YPHV), and for body cell mass, whose developmental tempo sped up around -1.00 YPHV. An increase in the rate of development was also observed close to -2.00 YPHV for phase angle (PA), although without accelerated phases. From a CA point of view, significant slope changes were found for all BC and bioimpendance variables, except for the calf muscle area. Although the starting points and the span of the accelerated phases were different, they subsided or disappeared at ~ 15 years, except for PA, whose growth waned at ~ 17 years.

Relative age and maturation selection biases in academy football

This study examined the simultaneous effects of relative age and biological maturity status upon player selection in an English professional soccer academy. A total of 202 players from the U9 to U16 age groups, over an eight-year period (total of 566 observations), had their relative age (birth quarter) and biological maturity (categorised as late, on-time or early maturing based upon the Khamis-Roche method of percentage of predicted adult height at time of observation) recorded. Players born in the first birth quarter of the year (54.8%) were over-represented across all age groups. A selection bias towards players advanced in maturity status for chronological age emerged in U12 players and increased with age; 0% of players in the U15 and U16 age group were categorised as late maturing. A clear maturity selection bias for early maturing players was, however, only apparent when the least conservative criterion for estimating maturity status was applied (53.8% early and 1.9% late maturing in the U16 age group). Professional football academies need to recognise relative age and maturation as independent constructs that exist and operate independently. Thus, separate strategies should perhaps be designed to address the respective selection biases, to better identify, retain and develop players.

The Influence of Maturity Offset, Strength, and Movement Competency on Motor Skill Performance in Adolescent Males

This study aimed to examine the extent to which maturity offset, strength, and movement competency influences motor skill performance in adolescent boys. One hundred and eight secondary school boys completed anthropometric and physical testing on two non-consecutive days for the following variables: Maturity offset, isometric mid-thigh pull absolute (IMTPABS) and relative (IMTPREL) peak force, resistance training skills quotient, 10-, 20-, and 30-m sprint time, countermovement jump height, horizontal jump distance, anaerobic endurance performance, and seated medicine ball throw (SMBT). The IMTPREL displayed significant small to large correlations with all performance variables (r = 0.27-0.61), whereas maturity offset was significantly correlated with IMTPABS (r = 0.69), sprint (r = 0.29-0.33), jump (r = 0.23-0.34), and SMBT (r = 0.32). Absolute and relative strength were the strongest predictors of all performance variables and combined with maturity to explain 21%-76% of the variance. Low and average relative strength boys were nearly eight times (odds ratio: 7.80, confidence interval: 1.48-41.12, p < 0.05) and nearly four times (odds ratio: 3.86, confidence interval: 0.95-15.59, p < 0.05) more likely to be classified as lower competency compared to high relative strength boys. Relative strength has more influence on motor skill performance than maturity when compared with movement competency.

Age- and Maturity-Related Variations in Morphology, Body Composition, and Motor Fitness among Young Female Tennis Players

The purpose of this study was to examine the effects of age and maturity on anthropometric and various fitness characteristics in young competitive female tennis players. Sixty-one players, aged 10.4-13.2 years (11.8 ± 0.8) were measured for standing and sitting heights, body mass, skinfolds, grip strength, and agility, and dichotomized into two age (U12 and U14) and maturity (earliest and latest) groups according to their chronological age and maturity status. The results revealed significant age effects for stature, sitting height, leg length, and hand grip in favor of the older players. Girls contrasting in maturation differed significantly for all anthropometric and physical performance variables except for body mass index (BMI), body fat percentage (BF%), and hexagon agility test. The earliest maturing group showed significantly higher values for anthropometric measures and better results in the hand grip test than the latest maturing group. After controlling for chronological age, differences were revealed between contrasting maturity groups in stature, sitting height, BF%, and the hand grip test. The findings highlight the age- and maturity-related trends in body size and muscular strength among young female tennis players in the pubertal period. Nevertheless, the differences in the body composition and agility of the contrasting age and maturity groups were negligible.

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.