Biological maturation, morphology, fitness, and motor coordination as part of a selection strategy in the search for international youth soccer players (age 15-16 years)

Acceptability and Feasibility of Portable Eye-Tracking Technology within a Children's Dynamic Sport Context: An Exploratory Study with Boys Who Play Grassroots Football

Teaching practices are moving from decontextualised to more representative curricula. Although this is argued to be a positive step, low motor competence is a continual issue in primary-aged school children. One methodological approach to investigate ways to improve motor competence, eye tracking, is moving to more representative tasks. So far, eye-tracking research using static activities has demonstrated a positive association between motor competence and earlier fixation and longer duration. However, this research has been constrained to laboratory settings and tasks, or discrete activities (e.g., throw and catch). This study seeks to understand how to conduct more representative eye-tracking research in primary school-aged children. To this end, thirteen 10-11-year-old children were fitted with an eye-tracker during a typical football coaching session. Children were asked acceptability-based questions, and eye-gaze data were captured to illustrate what children attended to under a representative dynamic football-based activity. Based on the voices of children and captured eye-gaze data, six practical implications for research in this population are proposed: (1) conduct eye-tracking research indoors (where possible); (2) ensure long hair or fringes are secured so as not to obscure line of sight; (3) run the same activity to increase comparability across children wearing the eye-tracker; (4) use a properly fitted backpack (if a backpack is to be used); (5) assure children about the capability and hardiness of the eye-tracker, as they do not need to change the way they move; (6) explain there may be some discomfort with the nose clip, head strap, and battery weight and ensure that children wish to continue.

Goldfit Soccer: A Multidimensional Model for Talent Identification of Young Soccer Players

Studies have provided empirical evidence on the prognostic relevance of test batteries and the "coach's eye" for talent identification. The aims were 1) to compare objective and subjective assessments as well as a combined soccer-specific potential index between future selected and non-selected players and 2) to evaluate the prognostic validity of a multidimensional model as a tool for talent identification in soccer. The sample was composed by 132 male players (14,5 ± 1,4 years; regional competitive level) from U13 to U17 age groups of a Brazilian soccer talent development program. Athletes completed a multidimensional test battery and were subjectively rated by their coaches for sporting potential. Players' success was evaluated five years later and was operationalized by achieving under-20 category of the Brazilian Championship or adult professional level (success rate, 15.9%). Confirming univariate prognostic validity, future selected outperformed non-selected players regarding 20-m sprint (p = .009), agility (p = .04), countermovement jump (p = .04), sit-and-reach (p = .001), Yo-Yo IR1 (p = .001), dribbling (p < .001), perceived competence (p = .007), peaking under pressure (p = .01), confidence/motivation (p = .03), coping skills (p = .03), intangibles (p < .001) and player potential (p < .001). A combined index (objective tests, athlete's assessments and coach's eye) named Gold Score Soccer (GSS) showed high prognostic validity (p < .001). A binary logistic regression estimated the probability of success (yes/not) with GSS, ambidextrous and predicted age at peak height velocity as predictors. This multidimensional model named GoldFit Soccer showed high prognostic validity (sensitivity = 85.7%; specificity = 83.8%; accuracy = 84.1%; area under the ROC curve = .93 [.87-.98]). Thus, GoldFit Soccer is a valid multidimensional scientific model for talent identification in soccer.

About the Predictive Value of a 3D Multiple Object Tracking Device for Talent Identification in Elite Ice Hockey Players

Purpose: The aim of this study is to verify if a single session on the NeuroTracker has predictive value in talent identification in ice hockey. Methods: Thirty-five male ice hockey players (aged 16-20) from the highest Canadian competition level for that age group participated in the study. A battery of tests (attention, working memory, time reproduction, pattern recognition, temporal equivalence, technical ability, and decision-making) was administered to verify the relation between various cognitive abilities, on-ice performance, and the baseline score on the NeuroTracker, which is claimed to solicit multiple cognitive functions. On-ice performance indicators were game-related statistics: games played, points (mean per game), on-ice goals differential, and draft rank. Results: Results show that the baseline score on the NeuroTracker is not associated with draft ranking, nor is it able to predict which players will perform best based on game-related statistics. However, the NeuroTracker baseline score does correlate with various tests involving working memory and attention. Conclusion: Currently, NeuroTracker is not specific enough to allow talent identification among same-level elite athletes in ice hockey.

Body size and three estimates of skeletal age: Relationships with strength and motor performance among male soccer players 9-12 and 13-16 years

OBJECTIVE

To estimate the associations between height, weight, and three estimates of skeletal age (SA) and the strength and motor performance of male soccer players in two chronological age (CA) groups, 9-12 (n = 60) and 13-16 (n = 52) years.

METHODS

Height, weight, strength (grip), speed (5 m, 20 m sprints), acceleration (time at crossing 10 m in 20 m sprint), agility (figure-of-eight run), power (vertical jump), and endurance (intermittent shuttle run) were measured. SA was assessed with the TW2 RUS, TW3 RUS, and Fels methods; each SA was expressed as the standardized residual of the regression of SA on CA (SAsr). Hierarchical multiple regression was used.

RESULTS

Body size accounted for ≥50% of the variance in grip strength in both CA groups; the body size × SAsr for each method and SAsr alone added little to the explained variance. Body size, body size × SAsr interactions, and SAsr per se with each method accounted for small percentages of variance in motor tasks among players 9-12 years, while body size explained a larger proportion of variance in motor tasks (except the endurance run) among players 13-16 years; body size × SAsr interactions for TW2 and TW3 more so than Fels added to the explained variances. For the endurance run, only SAsr per se with each method accounted for significant portions of the variance.

CONCLUSION

Body size and the three estimates of SA significantly influenced strength and motor performance, but the explained variance varied between CA groups and among SA methods and performance tasks.

Differences and Relationship between Body Composition and Motor Coordination in Children Aged 6-7 Years

BACKGROUND

The primary goal of this study was to investigate the relationship between body composition and motor coordination performance, and the secondary goal was to determine sex differences in body composition and motor coordination of preschool children.

METHODS

Forty-eight children (23 boys and 25 girls) underwent assessments for body composition and motor coordination using the Köperkoordinationstest für Kinder (KTK).

RESULTS

Linear regression analysis revealed significant associations between body composition and motor coordination in boys (p < 0.05) but not in girls. In boys, Body height (p = 0.01), Total muscle mass (p = 0.03), Total fat (p = 0.03), and Total water (p = 0.02) show statistically significant influence on single-leg jumps. Similar results were obtained for lateral jumps where there was a statistically significant influence of Body height (p = 0.01), Total muscle mass (p = 0.03), and Total water (p = 0.02). Interestingly, predictive variables showed no statistically significant influence on KTK overall score in boys (p = 0.42) nor in girls (p = 0.90).

CONCLUSIONS

The predictive system of morphological variables demonstrated significance only among boys in this age group and sample. Girls outperformed boys due to early maturation, resulting in better average KTK scores.

The role of peripheral vision during decision-making in dynamic viewing sequences

Decision-making in team sports necessitates monitoring multiple performers located at different distances (i.e., viewing eccentricities) from a critical information source. The processing of peripheral information is generally impaired under anxiety and when responding to stimuli located at larger eccentricities. These hypotheses have not been sufficiently tested in dynamic performance environments. We examined how pressure and eccentricities affect decision-making and visual behaviour in 4v4 basketball defensive scenarios using a head mounted display. Experienced players monitored plays from the first-person perspective (centre position) and made defensive steps towards opponents threatening the basket from different eccentricities under low- and high-pressure. To tax working memory, participants simultaneously performed a backward counting task. Players responded slower and with lower accuracy to opponents at larger eccentricities. Players mostly fixated on the ball-carrier, but over 50% of fixations were located on peripheral players, indicating that information in the periphery must be frequently updated with foveal vision (i.e., pivot strategy). When pressured, participants increased mental effort and improved counting performance; however, gaze behaviour and decision-making were relatively unaffected. Findings suggest that basketball players respond more quickly to opponents positioned at lower compared to higher eccentricities at the cost of impaired responses to opponents in the periphery.

Determining the effect of one decade on fitness of elite Austrian youth soccer players using propensity score matching

Current trends in attacking strategies and increases in external workload have led to a need for fast and well-conditioned athletes in modern soccer. More recently, progressions in speed, coordination, power and endurance were found over a decade in elite Austrian youth players. However, possible confounders such as relative age, maturation, learning effects, and academy philosophy may have influenced these changes. The present study aimed to determine the decade effect on fitness under statistical control of players' exact age, height, body mass, test location as well as total number of pretests and time interval between test and pretest. Players annually completed a battery of anthropometric, general and soccer-specific fitness tests. MANCOVA was calculated to identify the overall impacts of the covariates on fitness. To balance the covariates of initially 2,530 "former" (2002 to 2005) and 2,611 "recent" (2012 to 2015) players, 1:1 nearest neighbor propensity score (PS) matching was used, resulting in 587 U13, 573 U14, 475 U15, 325 U16, 262 U17, and 129 U18 matched pairs. The decade effect on fitness was assessed by independent t-tests and Cohen's d separately at each age group. Superior performances of recent players were found for linear sprint across all age categories (d = 0.154-0.476) as well as for agility (d = 0.125-0.340) and change-of-direction speed (d = 0.172-0.466) in U15 to U18. Reaction speed increased in U13 (d = 0.288) and U15 (d = 0.310). Flexibility reduced over the decade in all age categories (d = -0.151 to -0.589) and upper-limb power decreased (d = -0.278 to -0.347) in U13 and U14. Balancing the covariate distribution via PS matching generally confirmed previous findings, with fitness decade effects reflecting the athletic needs for modern soccer. Since fitness performance changed over time, reference values should be periodically updated. Coaches favor both physical and cognitive fast players nowadays. Thus, training should target all aspects of speed, without disregarding flexibility, upper-limb power and other preventive strategies that keep the players on the pitch.

Reliability and validity of the Körperkoordinationstest Für Kinder in Chinese children

Background

The Körperkoordinationstest Für Kinder (KTK) is a reliable and low-cost motor coordination test tool that has been used in several countries. However, whether the KTK is a reliable and valid instrument for use in Chinese children has not been assessed. Additionally, because the KTK was designed to incorporate locomotor, object control, and stability skills, and there is a lack of measurement tools that include stability skills assessment for Chinese children, the KTK's value and validity are worth discussing.

Methods

A total of 249 primary school children (131 boys; 118 girls) aged 9-10 years from Shanghai were recruited in this study. Against the Test of Gross Motor Development-3 (TGMD-3), the concurrent validity of the KTK was assessed. We also tested the retest reliability and internal consistency of the KTK.

Results

The test-retest reliability of the KTK was excellent (overall: r = 0.951; balancing backwards: r = 0.869; hopping for height: r = 0.918; jumping sideways: r = 0.877; moving sideways: r = 0.647). Except for the boys, the internal consistency of the KTK was higher than the acceptable level of Cronbach's α > 0.60 (overall: α = 0.618; boys: α = 0.583; girls: α = 0.664). Acceptable concurrent validity was found between the total scores for the KTK and TGMD-3 (overall: r = 0.420, p < 0.001; boys: r = 0.411, p < 0.001; girls: r = 0.437, p < 0.001).

Discussion

The KTK is a reliable instrument for assessing the motor coordination of children in China. As such, the KTK can be used to monitor the level of motor coordination in Chinese children.

Maturity-associated variation in the body size, physical fitness, technical efficiency, and network-based centrality measures in young soccer players

This study aimed to observe the relationships between the maturity status on the network-based centrality measures of young athletes in small-sided soccer games (SSG). The study included 81 male players (14.4 ± 1.1 years). Measurements included height, sitting height, body mass, and bone age (TW3 method). The applied protocols were the following: Countermovement Jump (CMJ), Yo-Yo Intermittent Recovery Test Level 1 (YYIRT1), Repeated Sprints Ability (RSA), observational analysis of techniques, and interactions performed by players in SSG. The relationship between the set of evaluated variables within each maturity status was obtained from the correlational analysis of networks (P < 0.05). The maturity status explained a significant portion of the variance in body mass (η² = 0.37), height (η² = 0.30), sitting height (η² = 0.30), and performance on the YYIRT1 (η² = 0.08), CMJ (η² = 0.14), and RSA (η² = 0.13). No effect of maturity status on network-based centrality measures of young athletes was identified (P > 0.05). For the late maturity group, there was a correlation between the degree of centrality and physical growth indicators (r_mean = 0.88). For players with maturation "on time", physical growth indicators relate to the degree of prestige (r_mean = 0.36). It is concluded that body size and bone age impact how late and on-time maturity groups interact within the match.

Tactical Knowledge by Decision Making and Motor Efficiency of Young Football Players in Different Playing Positions during a Three-a-Side Small-Sided Game

The aim of this study was to compare the tactical knowledge of young football players in different playing positions during a three-a-side small-sided game (SSG). Observational data was collected from 71 players (M = 12.16; SD = 1.55 years): 11 goalkeepers, 22 defenders, 15 midfielders, and 23 forwards. In total, 4 min of three-a-side SSGs (GR + 3 vs. 3 + GR) were recorded to assess tactical performance using a digital camera (GoPro Hero 6^® version 02.01). The SSGs were performed on a field with a constant area (36 × 27 m). Video analyses were performed using LongoMatch^® version 1.5.9 to record football performance; we then assessed tactical performance by using the Football Tactical Assessment System (Fut-Sat). This instrument evaluates the average of well-defined action indexes for each game in decision making principle and motor skills, specifically: (i) Decision Making Index (DMI); (ii) Motor Effectiveness Index (MEI); (iii) Effectiveness Index (I). The indexes were calculated by the ratio between the correct actions and the total. The Kruskal-Wallis test was used to evaluate differences between playing positions. The results showed that tactical performance by principles seems to be significantly different according to playing position. Differences were found between defenders and forwards (H = -11.92; p = 0.03) and defenders and midfielders (H = -16.13; p = 0.01) in contention principle. In conclusion, tactical knowledge of training based on the principles of the game can help coaches and players better understand and predict each player's actions during the game.

Observations of Player (de)Selection Within a Professional UK Soccer Academy

The present study engaged in an ethnographical observation of the processes used to determine player (de)selections within a professional academy. English category-2 youth academy players (n = 96) from U10-U16 age groups undertook anthropometric profiling (height, mass and somatic maturation) and fitness assessments (10 m, 20 m & 30 m linear sprints, 505-agility test, countermovement and squat jumps). Each players lead coach (n = 4) subjectively graded players utilising a red, amber and green (RAG) rating system on a weekly (current performance) and quarterly (perceived potential) basis, across 25 weeks. A MANCOVA, controlling for maturation, was applied to determine differences in (de)selection by physical performance. Mann Whitney-U tests were used to distinguish difference in (de)selection by subjective grading (weekly and quarterly). The key finding was that quarterly subjective gradings established a higher cumulative score of green ratings in selected players and a low cumulative score of red ratings, and vice versa for deselected players (P ≤ 0.001 to 0.03). However, whilst these findings suggest that quarterly subjective grades of potential were able to provide the best predictors for player (de)selection, the findings should be viewed with caution due to high potential for confirmatory bias.

Changes in Estimated Body Composition and Physical Fitness of Adolescent Boys after One Year of Soccer Training

Sports participation is one of the most popular forms of physical activity among youngsters. This study aimed to examine the changes in the estimated body composition, strength, and flexibility of adolescent boys after 12 months of soccer training compared with those of age-matched controls with non-sports participation. We assessed 137 boys (62 soccer players and 75 controls) at baseline (TM1) and 12 months later (TM2). The differences in estimated body composition, strength, and flexibility were investigated using a repeated measure analysis of variance. The analysis revealed a significant main effect of soccer training on fat mass (F = 73.503, p ≤ 0.01, η2 = 0.59) and fat-free mass (F = 39.123, p ≤ 0.01, η2 = 0.48). Over time, the soccer group decreased their fat mass and increased their fat-free mass, while the opposite results were observed for the controls. Among physical fitness tests, a substantial effect of soccer training was evidenced for the sit-up performance (F = 16.224, p ≤ 0.01, η2 = 0.32). Regarding the time factor, significant effects were noted for height and handgrip strength. No significant differences were detected for flexibility. Overall, the benefits of soccer training were exhibited by the larger improvements in fat mass, fat-free mass, sit-ups, and handgrip strength performance, underlining the important role of soccer participation during adolescence.

Age and Maturation Matter in Youth Elite Soccer, but Depending on Competitive Level and Gender

This study aimed to explore the relevance of the relative age effect (RAE), maturity status and anthropometry, and their influence on coaches' assessment of players' performance, analyzing both genders and different types of academies (elite vs. non-elite). The sample included 603 soccer players (385 male), from the under 12 (U12), under 14 (U14) and under 16 (U16) categories, belonging to elite and nonelite teams. Coaches' assessment of players' performance, chronological age, anthropometric characteristics, maturity offset (MO) and peak height velocity (PHV) were registered. Our results showed that RAE was present in both genders within the elite, but not in the nonelite academies. Early maturity players were overrepresented in the male elite, but not in the female academies. No relationship was found between RAE and anthropometry in male elite academies. Male elite players showed better anthropometric characteristics than nonelite players, while this pattern of results was not found for female players. The coaches' assessment on players' current performance was not influenced by the chronological age nor anthropometry, but it was linked to the PHV. Coaches from nonelite academies rated better in current assessment of performance the taller players. Our findings suggest that maturity status and RAE play an independent and important role in the talent selection process.

Physical Fitness Variations between Those Playing More and Those Playing Less Time in the Matches: A Case-Control Study in Youth Soccer Players

The purpose of this study was (i) to compare two groups (players with more vs. less match play time) regarding body composition, vertical and horizontal jumping performance, and aerobic capacity; and (ii) to test the relationships between physical fitness and play time. This study followed a case-control design in which the outcome was playtime, and the causal attribute was physical fitness. Sixty-six youth male soccer players from under-16 (n = 21), under-17 (n = 19), under-18 (n = 12), and under-19 (n = 14) age groups were monitored for match play time during five months of observation. Inclusion criteria consisted of (1) no absence of more than a week due to injury or other conditions during the five months of observation and (2) physical assessments having been done simultaneously with those of the other players (at the beginning of the season). The exclusion criteria were (1) not participating in one week or more of training sessions, and (2) not participating in the physical fitness assessments. At the beginning of the season, players were assessed for anthropometry (height, body mass, skinfolds), countermovement jump, triple hop bilateral and unilateral jump, and aerobic capacity using the Yo-Yo Intermittent Recovery Test, level 2 (YYIRT). The group that played more time had significantly greater YYIRT results (+28.2%; p = 0.009; Cohen’s d = 0.664). No other significant differences were found between those who played more and fewer minutes. Moderate and significant linear positive correlations were found between YYIRT and play time in the under-19 group (r = 0.423; p = 0.031) and overall (r = 0.401; p < 0.001). In the case of the under-17 group, moderate and significant linear positive correlations were found between TSA and play time (r = 0.473; p = 0.041). This suggests that aerobic and anaerobic capacity is related to play time while jumping performance and fat mass seem not to play an essential role in play time.

Predictive Value of Repeated Jump Testing on Nomination Status in Professional and under 19 Soccer Players

Soccer clubs invest time and money in multidimensional identification practices, but the field implementation is still problematic. The repeated vertical jump test (RVJ), as an alternative to the monodimensional vertical jump, may offer similar prognostic value. Therefore, the prognostic validity of 15 RVJ within professional (PRO, n = 24) and under 19 years old (U19, n = 20) Greek male soccer players was examined. T-test, binomial logistic regression, and receiver operating characteristic for prognostic validity of anthropometric and performance values in predicting PRO status were applied using Jamovi version 2.3.3.0. Significant group differences presented in body height and mass, body mass index (BMI), maximum and average jump height, and relative jump power. The predicting model was significant (x²(2) = 17.12, p < 0.001). Height and BMI were positive predictors of the PRO status (b = 21.66, p = 0.008 and b = 0.94, p = 0.014, respectively). The model was 73% accurate, 75% specific, and 71% sensitive, with excellent area under the curve. The RVJ test demonstrated outstanding discriminating prognostic validity. Until the applicability of the multidimensional models in predicting future player status is further established, field practitioners may use the simplistic RVJ testing to predict future status among male soccer players.

Combined effect of game position and body size on network-based centrality measures performed by young soccer players in small-sided games

This study verified the effects of body size and game position on interactions performed by young soccer players in small-sided games (SSG). The sample consisted of 81 Brazilian soccer players (14.4 ± 1.1 years of age). Height, body mass, and trunk-cephalic height were measured. SSG was applied in the GK + 3v3 + GK format, and Social Network Analyses were carried out through filming the games to obtain the following prominence indicators: degree centrality, closeness centrality, degree prestige, and proximity prestige, in addition to network intensity and number of goals scored. Factorial ANCOVA (bone age as covariate) was used to test the effects of game position, body size, and respective interaction on centrality measurements (p < 0.05). Similarity between game positions in body size indicators (p > 0.05) was observed. The game position affected degree centrality (p = 0.01, η² = 0.16), closeness centrality (p  = 0.01, η² = 0.11), and network intensity (p = 0.02, η² = 0.09), in which midfielders presented the highest network prominence values when compared to defenders and forwards. In conclusion, midfielders are players with high interaction patterns in the main offensive plays, which behavior is independent of body size.

Player-labelling as a solution to overcome maturation selection biases in youth football

The fact that potentially skilled, but biologically later-maturing athletes are less likely to be selected into talent development programmes (TDP) can represent a failure of Talent Identification (TID) in sports. To overcome maturation selection biases, maturation independent TID should be established to include less mature, but talented athletes in TDP more frequently. Using a randomised parallel-group design, this study aimed to evaluate the effect of labelling under-11 (U₁₁) Swiss male youth football players (n = 24, age = 11.0 ± 0.3 years) via maturation-ordered shirt numbers during rank assessment by talent scouts (n = 83, scout experience = 4.8 ± 2.4 years). Following observation of video recorded selection tournaments, player-labelling "informed" scouts were significantly more likely to rank less mature players higher on their player potential, t(81) = 2.57, p = .012, d = -0.6, 95% CI [-1.00, -0.13], than "uninformed" scouts. As altered rankings assisted less mature players, player-labelling may offer a practical and feasible strategy to improve TID by removing possible maturation selection biases. To address maturation selection biases and the potential positive impact of player-labelling more broadly, further research on both male and female athletes in various age categories and sports contexts is recommended.

Perception of Affordances for Dribbling in Soccer: Exploring Children as Architects of Skill Development Opportunity

This study examined affordance perception for soccer dribbling using a mixed-methods approach in male grassroots soccer players. We examined how children construct and perceive skills practices for dribbling in soccer. Fourteen boys aged 10–11 years (Mean ± SD = 10.8 ± 0.4 years) who were regularly engaged in grassroots soccer participated in the present study. Children were provided with ten soccer cones and asked to create their own soccer dribbling pattern that would enable them to maximise the number of touches with a football and then dribble the ball in the pattern they had created for a 1 min period. Children were interviewed to explore their perception of affordances for soccer dribbling. The test of gross motor development-3 was used to assess fundamental movement skills (FMS), and the UGent soccer dribbling test was used to assess soccer dribbling skills. Children self-rated their own ability for soccer dribbling, as did their coaches. Pearson’s correlations were employed to examine the associations between quantitative variables, and thematic analysis was used to explore qualitative data. Results of the present study suggest that those children who created patterns with less space between cones accrued more touches of the football in their dribbling task (r = −0.671, p = 0.03). Children with a higher perception of their own dribbling ability had higher scores for FMS (r = 0.604, p = 0.049). Those children who scored better in actual soccer dribbling had higher scores for FMS (r = −0.746, p = 0.012) and were rated as better dribblers by their coaches (r = −0.67, p = 0.03). Interview data suggest a feedback loop between perception of ability and actual ability, which influenced the dribbling patterns that were created. This suggests that dribbling performance is scaled to the (perceived) action capabilities of the children, and children can act as architects in their own skill development.

School-Age Children's Actual Motor Competence and Perceived Physical Competence: A 3-Yr Follow-up

PURPOSE

This study examined school-age children's actual motor competence (MC) and perceived physical competence (PC) over 3 yr along with the covariate effects of gender and body mass index (BMI).

METHODS

Participants were 1121 (girls 573, boys 548) children (mean age, 11.26 ± 0.32 yr) from 35 randomly selected public schools across Finland. MC was assessed using three movement tests targeting locomotor, stability, and object control skills, and PC was assessed using the sport competence subscale of the Physical Self-Perception Profile via four-phase monitoring.

RESULTS

MC and PC remained stable over time. Of the three variables, locomotor skills showed the strongest association with PC. Lower BMI was associated with advanced MC skills and a less steep decrease in locomotor and stability skills over time.

CONCLUSIONS

The acquisition of fundamental motor skills in childhood and early adolescence is a prerequisite for enhancing MC and PC. The contribution of locomotor skills to PC indicated that versatile lower limb strength, speed, dynamic balance, and movement skills are important for positive subjective beliefs about PC capability. Increasing the MC skills of the children in most need, particularly those with high BMI scores, merits special attention.

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.

Relationship between Variations in the Accumulated Workload and the Change of Direction Ability in Elite Young Soccer Players

Background: The main aim of this study was to evaluate the relationships between training workload (WL) parameters with variations in the change of direction (COD) in under-16 soccer players. Methods: Twenty-seven under-16 elite soccer players were daily monitored for their WL across 15 weeks during the competitive soccer season. Additionally, players were assessed two times for anthropometric measures (weight, height, sitting height and leg length), COD performance (modified 505 test) and maturity offset measured using the peak height velocity (PHV). Results: A correlational analysis was performed to determine the relationship between the variation in COD performance and accumulated WL parameters. Moreover, a regression analysis was executed to explain the variations in the percentage of COD performance considering the accumulated WL parameters and PHV of the season (r = 0.93; p ≤ 0.01) and training monotony during the early-season (r = 0.53; p ≤ 0.05). There were associations between the acute workload during the start of the season and the COD during the end of the season (r = 0.47; p ≤ 0.05). The multiple linear regression analysis showed that 55% of the variation in COD performance between the early and end of season could be explained by the acute or chronic WL, training monotony or strain and the PHV. Conclusions: This information might be useful for practitioners and coaches aiming to improve the COD performance in youth soccer players during an entire competitive season.

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.

Whole-Body Vibration Effects on Flexibility in Artistic Gymnastics—A Systematic Review

It is well documented that whole body-vibration training has effects on muscle strength and flexibility, blood circulation, decreases pain perception and strengthens bone and tendon. Although whole body-vibration has benefits in athletes’ flexibility, we are not sure what its actual effects are in artistic gymnastics (since they already have stunning flexibility). Hence, the aim of this study was to analyse the studies on whole-body vibration in artistic gymnastics and to present the effects on flexibility. The search and analysis were carried out in accordance with PRISMA guidelines. The databases search (PubMed, Scopus, Google Scholar, Cochrane Library, ProQuest, EBSCOhost and Science Direct) yielded 18,057 potential studies. By the given inclusion criteria (studies from 2005 to 2022; full-text published in English; the study included male and female gymnasts as samples, and that participants were tested for evaluation of flexibility by whole-body vibration method), a total of 9 full-text studies were included, with a total of 210 participants, both male and female. As far as the measured flexibility tests conducted, front split, sit and reach and bridge were evaluated, while obtained results were 9.1–39.1%, 2.79–6.7%, 6.43–7.45%, respectively. All studies have conducted same vibration frequency (30 Hz) with same amplitude of displacements (2 mm), except for the one study who did not show the information of implemented amplitude. After analysing the obtained results, it can be concluded that the usage of whole-body vibration platform shows flexibility improvements in artistic gymnasts, both male and female. In addition, a combination of whole-body vibration and traditional static stretching may enhance the flexibility in artistic gymnasts. However, these results should be taken with caution. Since this review did not reveal the optimal vibrational protocol, it is necessary to invest time during the implementation of various vibrational experimental protocols, so future research is required.

Reliability and validity of a modified Illinois change-of-direction test with ball dribbling speed in young soccer players

The purpose of this study was to assess test-retest reliability, discriminative and criterion-related validity of the modified Illinois change-of-direction (CoD) test with ball dribbling-speed (ICODT-BALL) in young soccer players of different biological maturity and playing levels. Sixty-five young male soccer players (11.4 ± 1.2 years) participated in this study. The participants were classified according to their biological maturity (pre- and circumpeak height velocity [PHV]) and playing-level (elite and amateur players). During the test-retest time period of two weeks, the following tests were performed during week one and as retest during week two: ICODT-BALL, ICODT, 4 × 9-m shuttle-run, countermovement-jump, triple-hop-test, maximum-voluntary isometric-contraction of back-extensors, Stork, Y-Balance, 10 and 30-m sprints. The ICODT-BALL showed excellent relative (r = 0.995, p < 0.001; ICC = 0.993) and absolute (SEM < 5%; SEM < SWCs_{(0.2, 0.6, 1.2)}) reliability. The circum-PHV (22.8 ± 1.7-s) and elite (22.5 ± 0.9-s) players showed better ICODT-BALL performance than their pre-PHV (24.2 ± 2.5-s) and amateur (25.1 ± 2.8-s) counterparts (p = 0.028 and p < 0.001, respectively). The ICODT-BALL showed "very good" (AUC = 0.81) discriminant validity when comparing the elite and amateur players, and "moderate" (AUC = 0.67) discriminant validity when compared to pre-PHV and circum-PHV boys. ICODT-BALL demonstrated "large" positive associations with the ICODT (r = 0.65; 41.8% shared-variance) and sprint tests (r ≥ 0.52; 27.3 to 34.8% shared-variance). In addition, results showed "moderate" negative associations between ICODT-BALL and strength, and power measures, as well as a "small" negative relationship with balance tests. In conclusion, the ICODT-BALL is a valid and reliable test to evaluate the ability to quickly change directions while ball dribbling in young soccer players. Therefore, practitioners can use the ICODT-BALL as a tool for talent identification.

The confounding effect of biological maturity on talent identification and selection within youth Australian football

This study measured the influence of biological maturity across numerous performance parameters for talent identification in Australian football. Anthropometry, estimated maturity status using a maturity ratio from anthropometric measurements and chronological age, motor competence, physical fitness and small-sided match involvements of 227 U13-U15 high-level academy athletes were assessed. Multivariate analysis of variance revealed significant moderate effects of maturity status on physical fitness (p = 0.008, ES = 0.07) and significant large effects on anthropometry (p = 0.001, ES = 0.20), but not on motor competence or match involvements. Univariate analyses of variance demonstrated significant large effects of maturity on anthropometry, but only one subset of physical fitness (i.e. lower-body power). U15 players selected into a U16 development programme were biologically older thandeselected players, despite selection being independent of maturity when a categorical descriptor was used. This study confirms that maturation affects anthropometry and certain measures of physical fitness in youth Australian football players, but not match involvements and motor competence. Furthermore, a player's maturity could affect selection and progression into advanced academy programmes. Involvements and motor competence should be included in multidimensional assessment batteries for Australian Football as they appear less confounded by maturity than fitness and anthropometry.

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.

Exploring the importance of diversified physical activities in early childhood for later motor competence and physical activity level: a seven-year longitudinal study

BACKGROUND

Research indicates that childhood motor competence (MC) can predict physical activity (PA) levels later in life and it has been argued that frequently engaging in a wide diversity of physical activities will eventually improve children's MC. However, no longitudinal or experimental studies have confirmed this theoretical rationale. The aims of this study are to explore the longitudinal associations between diversified physical activities at age six and later MC and PA (time spent in moderate-to-vigorous PA) (age nine and 13). Furthermore, we explore to what extent the longitudinal association between diversified physical activity and PA is mediated by MC.

METHODS

Longitudinal data from the Copenhagen School Intervention Study were used for this analysis, where 704 participated (69% response rate). Diversified physical activity (self-reported), MC (The Körperkoordinationstest für Kinder battery of postural stability and locomotor skills) and PA (accelerometer) were assessed in the children at age six, age nine and age 13. A total of 654 participated in at least two of the measures and, therefore, were included in the analysis. Two structural equation models were constructed, with diversified physical activity at age six and MC and PA at age nine as predictors of PA and MC at age 13.

RESULTS

The data from both models demonstrated good model fit. Diversified physical activity at 6 years of age was significantly associated with physical activity and MC at age 13, when adjusting for sex, age, intervention, weight, height, and previous levels of PA and MC. Diversified physical activity at age six was also positively associated with PA and MC at age nine, which were, in turn, positively related to PA at age 13 but to a lesser degree than diversified PA at age six. The association between diversified physical activity at age six and PA at age 13 was not mediated by MC at age nine.

CONCLUSIONS

The results of this study indicate that diversified physical activity at age six is important for the development of MC and PA in adolescence. Increasing the diversity of children's daily physical activities, not only the amount and intensity, seems important for future PA behavior and thereby health promotion in a life course perspective.

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.

Performance Comparisons of Youth Weightlifters as a Function of Age Group and Sex

This study was designed to provide an overview of weightlifting performance as a function of age group and sex and evaluate the potential of countermovement jump height (CMJH) as a tool to gauge performance potential. Data from 130 youth athletes (female, n = 65 & male, n = 65) were used to examine progression of performance (Total and Sinclair total) and the relationship between CMJH and Sinclair total while considering interactions between CMJH and age and/or sex. ANOVAs with post hoc analyses revealed that both totals had a statistical first-order polynomial interaction effect between age group and sex and the difference between age groups of 12-13 and 14-15 years old was statistically greater for male than female. A linear model, developed to examine the relationship, revealed that CMJH and CMJH x sex x age rejected the null hypothesis. Our primary findings are that male youth weightlifters have a higher rate of performance progression, possibly owing to puberty, and CMJH may be a better gauging tool for older male youth weightlifters.

How soccer scouts identify talented players

Scouts of soccer clubs are often the first to identify talented players. However, there is a lack of research on how these scouts assess and predict overall soccer performance. Therefore, we conducted a large-scaled study to examine the process of talent identification among 125 soccer scouts. Through an online self-report questionnaire, scouts were asked about (1) the players' age at which they can predict players' soccer performance, (2) the attributes they consider relevant, and (3) the extent to which they predict performance in a structured manner. The most important results are as follows. First, scouts who observed 12-year-old and younger players perceived they could predict at older ages (13.6 years old, on average) whether a player has the potential to become a professional soccer player. This suggests that scouts are aware of the idea that early indicators of later performance are often lacking, yet do advise on selection of players at younger ages. Second, when identifying talented players, scouts considered more easily observable attributes, such as technical attributes. However, scouts described these often in a broad sense rather than in terms of specific predictors of future performance. Finally, scouts reported that they assess attributes of players in a structured manner. Yet, they ultimately based their prediction (i.e. final score) on an intuitive integration of different performance attributes, which is a suboptimal strategy according to existing literature. Taken together, these outcomes provide specific clues to improve the reliability and validity of the scouting process. HighlightsBased on a large sample of soccer scouts, we examine three issues that are important in the process of identifying talented soccer players: The age at which good performance predictions can be made, which attributes are relevant predictors, and how performance predictions are formed.Scouts who observe players in young age cohorts believe that the age at which they can predict performance is older than the players they typically scout, suggesting that they are aware that early indicators of performance are often lacking.Technical performance attributes are considered as most important performance predictors by scouts, but these are often described in a broad - rather than specific - sense.Scouts indicate that they predict performance in a structured manner, but form their overall performance prediction on an intuitive integration of different performance attributes, which can be a suboptimal approach.

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.

Initial fitness, maturity status, and total training explain small and inconsistent proportions of the variance in physical development of adolescent footballers across one season

To investigate how initial fitness, maturity status, and training time explain changes in physical performance across one season. Eighty-eight adolescent male footballers, representing four age categories (Under 15 [n = 12], Under 14 [n = 21], Under 13 [n = 25], Under 12 [n = 30]), were tested using physical performance tests (20 m sprint, change of direction, squat jump and yo-yo intermittent recovery test level 1 [YYIRTL1]) and maturity offset at the season start (Test 1) and end (Test 2). Multiple regression determined the proportion of variance in test score changes, explained by three predictor variables: initial fitness (i.e., Test 1), maturity offset change, and training time. With combined categories, predictor variables explained 0.051 to 0.297 of the variance in physical performance score changes. Analysing age categories separately, predictor variables explained 0.047 to 0.407 (20 m sprint), 0.202 to 0.626 (change of direction), 0.336 to 0.502 (squat jump), and 0.196 to 0.777 (YYIRTL1) of variance in test score changes. Of the limited differences in relative predictor contribution, Test 1 was the strongest predictor of test score change. Initial fitness, maturity status change, and training time explain small and inconsistent proportions of variance in adolescent footballers' physical development across one season.

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.

Are Early or Late Maturers Likely to Be Fitter in the General Population?

The present study aims to identify the optimal body-size/shape and maturity characteristics associated with superior fitness test performances having controlled for body-size, sex, and chronological-age differences. The sample consisted of 597 Tunisian children (396 boys and 201 girls) aged 8 to 15 years. Three sprint speeds recorded at 10, 20 and 30 m; two vertical and two horizontal jump tests; a change-of-direction and a handgrip-strength tests, were assessed during physical-education classes. Allometric modelling was used to identify the benefit of being an early or late maturer. Findings showed that being tall and light is the ideal shape to be successful at most physical fitness tests, but the height-to-weight “shape” ratio seems to be test-dependent. Having controlled for body-size/shape, sex, and chronological age, the model identified maturity-offset as an additional predictor. Boys who go earlier/younger through peak-height-velocity (PHV) outperform those who go at a later/older age. However, most of the girls’ physical-fitness tests peaked at the age at PHV and decline thereafter. Girls whose age at PHV was near the middle of the age range would appear to have an advantage compared to early or late maturers. These findings have important implications for talent scouts and coaches wishing to recruit children into their sports/athletic clubs.

A multilevel analysis of gross motor coordination of children and adolescents living at different altitudes: the Peruvian Health and Optimist Growth Study

BACKGROUND

Gross motor coordination (GMC) is a potential correlate of lifestyle behaviours and health outcomes in childhood and adolescence.

AIMS

The aim of this study was to examine how sex, age, biological maturation, overweight, stunting, and physical fitness are associated with GMC in children and adolescents from Peru, and to examine associations between geographical area of residence, school-level characteristics, and GMC.

SUBJECTS AND METHODS

The sample included 7408 subjects, aged 6-14 years, from sea level, Amazon and high-altitude regions of Peru. A composite marker of total coordination was derived by the sum of scores from each test (GMC_T). Overweight was identified using BMI, and biological maturation, physical fitness, and stunting were assessed. School characteristics were obtained via an objective audit.

RESULTS

Boys (β = 12.23 ± 0.90) and older children (β = 13.37 ± 0.64) had higher GMC_T than girls and younger children, respectively. Overweight was associated with lower GMC_T (β = -5.23 ± 0.80), whereas fitness was positively associated with GMC_T (β = 6.30 ± 0.25). Biological maturation was not a predictor; however, stunting was negatively associated with GMC_T (β = -3.71 ± 1.56). Subjects living in the Amazon had higher GMC_T than those at sea level (β = 16.57 ± 4.73). Five of nine school-level predictors (number of students, playground area with obstacles, multi-sports roofed, frequency and duration of Physical Education classes) were significant predictors of GMC_T.

CONCLUSIONS

Child- and school-level variables were significantly associated with GMC_T in this sample. These findings are important for the Peruvian community, especially school principals, councils and physical education teachers, helping them to define more efficient strategies and action plans to increase motor coordination in children.

Relationship between Anthropometric Parameters and Throwing Speed in Amateur Male Handball Players at Different Ages

The objectives of this study were: (i) to analyse anthropometric parameters and throwing speed from seven meters in amateur male handball players of different ages; (ii) to know the relationship between anthropometric parameters and throwing. One hundred seventy-six male handball players (16.5 ± 5.1 years old) participated in the study, classified according to their age: senior (n = 35), U18 (n = 30), U16 (n = 37), U14 (n = 50) and U12 (n = 24). All participants were evaluated by anthropometric measurements (height, weight, body mass index, arm span, hand width) and throwing speed from 7 m standing. A one-way analysis of variance with a Bonferroni post hoc test was used to establish the differences between teams. Pearson’s simple correlation coefficients were calculated between analyse anthropometric parameters and throwing speed. Multiple linear regression was used to predict the throwing speed. Only BMI was related with throwing speed in all age groups (0.506 > r < 0.813, p < 0.05). Throwing speed was predicted (24–72%) with only one or two variables in each model. The selected variables were: BMI, arm span in U16 model and height U14 model, and the BMI, arm span and height are proved to be good predictors of TS in male handball players.

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.

Decline of physical activity in early adolescence: A 3-year cohort study

This study analyses the changes of moderate-to-vigorous physical activity (MVPA) in a cohort of boys and girls aged 11 (n = 50) and 14 (n = 50). Physical activity was assessed with Bodymedia SenseWear Pro Armband monitor for 6 days in October 2013 and October 2016, considering 90% of daily wear time (21h and 40min). The initial sample (n = 160) included the children who wore the monitors at age 11 but the final analyzed sample included only those children from the initial sample (n = 50), whose data fulfilled the inclusion criteria at age 11 and 14. Physical fitness and somatic characteristics of the final sample (n = 50) were compared to a representative sample of Slovenian schoolchildren at ages 11 (n = 385) and 14 (n = 236) to detect possible bias. Changes in MVPA were controlled for maturity using the timing of adolescent growth spurt as its indicator. The average MVPA decreased more than one quarter (34.96 min) from age 11 to age 14. Children were significantly more active at age 11 than at age 14 (p < 0.01, d = 0.39). The timing of puberty onset in girls was significantly earlier (12.01 ± 1.0 years) (p < 0.01) than in boys (13.2 ± 0.75 years) (p < 0.01, d = 1.35). There was a significant gender difference in moderate-to vigorous physical activity at age 14 (p < 0.05, η2 = 0.12) and between moderate-to vigorous physical activity at age 11 and 14 (η2 = 0.11). After controlling for the timing of adolescent growth spurt the girls at age 11 showed significantly higher level of physical activity than at age 14 (p < 0.01, η2 = 0.17). Early adolescence is crucial for the development of physical activity behaviours, which is especially pronounced in girls. The significant decline of MVPA between ages 11 and 14 in Slovenia are likely influenced by environmental changes since the timing of adolescent growth spurt did not prove as a factor underlying the decline of MVPA.

Influence of biological maturation on speed, jump, and endurance in high-level youth soccer players

ABSTRACT The goal of this study is to identify the influence of the maturity state in the physical components of the high level youth male soccer players of an elite club in Brazil. Eighty-seven young male soccer players participated in this study, distributed in 34 U-14 players, 23 U-16 players and 30 U-19 players. Peak height velocity (PHV) was estimated: Pre-PHV (<-1.0 years, n=13), mid-PHV (-0.99 to 0.5 years, n=41), and post-PHV (>0.5 years, n=33). Running-based anaerobic sprint test, squat jump, yo-yo and 30m speed test were performed. The results of this study suggest that the maturational development influences vertical jump. VO2max, yo-yo test distance, fatigue index and power. This information is essential for the identification and effective development of talented football players.

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

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

How Does Biological Maturation and Training Experience Impact the Physical and Technical Performance of 11-14-Year-Old Male Basketball Players?

This study (1) investigated the effects of age, maturity status, anthropometrics, and years of training on 11–14-year-old male basketball players’ physical performance and technical skills development, and (2) estimated the contribution of maturity status and training years on players’ physical and technical performances. The sample consisted of 150 participants, average age 13.3 ± 0.7 years, grouped by early, average, and late maturation. Biological maturation, anthropometry, and training data were collected using standard procedures. Measures of physical performance assessed included: aerobic fitness, abdominal muscular strength and endurance, static strength, lower body explosive power, upper body explosive power, speed, and agility and body control. Basketball-specific technical skills were also recorded. Analysis of variance (ANOVA) and analysis of covariance (ANCOVA) were used to compare group differences. Results indicated that early maturers were taller, heavier, and had greater strength, power, speed, and agility (p < 0.05). When controlling for age, height, and body mass, early maturers remained stronger, quicker, and more agile (p < 0.05). They were also more skillful in the speed shot shooting test (p < 0.05). Apart from tests of aerobic fitness, abdominal muscular strength and endurance, and lower body explosive power, maturity status was the primary contributor to the variance in the physical performance tests. Years of training was the primary contributor to the variance in the technical skills tests. Whilst physical performance was dependent on maturity status, technical skills were influenced by years of training. Since both biological maturation and years of training play an important role in basketball performance, we recommend that coaches consider the effects of these two confounders when recruiting and selecting youth basketballers.

Maturational Development as a Key Aspect in Physiological Performance and National-Team Selection in Elite Male Basketball Players

PURPOSE

To determine the discriminators as variables to select the under-16 national-team players and to examine the influence of biological age on physical/technical parameters among young basketball players.

METHODS

Thirty-four under-15 male basketball players performed several anthropometrical (height, wingspan, body mass, and fingers length) and physical (jumping, sprinting, throwing, flexibility, change-of-direction speed, and aerobic fitness) tests during the under-15 male national-team training camp. Maturity offset, lower-limb asymmetry index, and power outputs for jumping and sprinting were also computed. In addition, game performance was taken into consideration using game-related statistics (assists, turnovers, steals, rebounds, blocks, and points) of 5 games of during the previous regional tournament (April 2016). Cluster analysis was used to analyze the between-maturation status (prepubertal, pubertal, and postpubertal) differences in physical parameters.

RESULTS

The postpubertals showed a significantly better performance in power outputs (jumping and sprinting), throwing abilities, and blocks, whereas prepubertal performed significantly better in aerobic fitness and assists. Receiver-operating-characteristic curve confirmed maturational status (area under the curve [AUC] = 0.804; P < .05) and training experience (AUC = 0.789; P < .05) as the most important attributes in predicting under-16 national-team selection. Players with more than 5.5 years of training experience and less than 1.4 y to the age at peak height velocity were most likely to be selected.

CONCLUSION

Maturational status seems to be a key variable that increases the probability of selection for the Portuguese under-16 national team.