Barbara C. H. Huijgen

Development of dribbling in talented youth soccer players aged 12-19 years: a longitudinal study.

Abstract The aims of the current study were to assess the development and determine the underlying mechanisms of sprinting and dribbling needed to compete at the highest level in youth soccer. Talented soccer players aged 12–19 years (n = 267) were measured on a yearly basis in a longitudinal study over 7 years, resulting in 519 measurements. Two field tests, the Shuttle Sprint and Dribble Test and the Slalom Sprint and Dribble Test, were assessed. Anthropometric characteristics, years of soccer experience, and duration of practice were recorded. The longitudinal data were analysed with multi-level modelling. Comparing the two tests at baseline, low correlations were observed (sprinting: r = 0.49; dribbling: r = 0.22), indicating that each test measures distinct qualities (acceleration vs. agility). Low-to-moderate correlations were found between dribbling and sprinting within each test (Shuttle Sprint and Dribble Test: r = 0.54; Slalom Sprint and Dribble Test: r = 0.38). Both dribbling and sprinting improved with age, especially from ages 12 to 14, but the tempo of development was different. From ages 14 to 16, sprinting improved rapidly in contrast to dribbling; this was especially evident on the Slalom Sprint and Dribble Test. In contrast, after age 16 dribbling improved considerably but sprinting hardly improved. Besides age, the factors that contribute to dribbling performance are lean body mass, hours of practice, and playing position.

Soccer Skill Development in Professionals

The purpose of this study was to investigate the relationship between the development of the technical skill dribbling during ages 14-18 and adulthood playing level. The results gained insight in the required level of the technical skill dribbling during adolescence to be capable of becoming a professional soccer player. Talented players (n=131), aged 14-18 were measured while they were part of a developmental soccer program, testing took place annually. The players were identified as professional (n=54) or amateur (n=77) later on in their career (age>20). In total 238 measurements of dribbling performance were assessed by means of the Shuttle Dribble Test. A longitudinal model estimated the development for optimal dribbling performance (peak dribbling) and for dribbling performance under fatigue (repeated dribbling), for players ultimately reaching professional status and for players reaching amateur status. The longitudinal results showed that during adolescence the talented players who ultimately became professionals were on average 0.3 s faster on 30m peak dribbling performance and on average 1 second faster on 3 x 30m repeated dribbling performance than the players who ultimately turned amateur (p=0.001). It is concluded that during adolescence dribbling performance can assist in identifying the best players for the future.

Soccer Endurance Development in Professionals

The development of intermittent endurance capacity, its underlying mechanisms and role in reaching professional level in soccer was investigated. The sample included 130 talented youth soccer players aged 14-18, who became professional (n = 53) or non-professional (n = 77) players in adulthood. In total 229 Interval Shuttle Run Test (ISRT) scores were taken over five years. Players who became professionals improved from age 14 to 18 on average from 68 to 109 runs in contrast to players who remained amateurs (from 73 to 93 runs). A longitudinal model was developed using linear mixed models procedures. Intermittent endurance capacity can be predicted adequately with a two-level hierarchical model (p < 0.05). Anthropometric characteristics and playing position did not improve model fit (p > 0.05). The estimated ISRT score necessary to reach professional level is: ISRT=-375.77-62.89+(51.20+4.20)* age-1.50* age (2)+3.54* hours of soccer training+1.18* additional training hours. In conclusion, intermittent endurance capacity improves with age in talented youth soccer players. From age 15 players who reached the professional level show a faster development than their non-professional counterparts. This development is positively influenced by both soccer specific and additional training.

Soccer Skill Development in Talented Players

The aim of the study was to gain insight into the development of soccer-specific skills and whether differences between talented players exist on the Loughborough Soccer Passing Test (LSPT). Two scores were derived from the LSPT: 1) execution time: time to complete 16 passes (speed) and 2) skill performance time: execution time including bonus and penalty time for accuracy. The study consisted of 2 parts, the first of which incorporated a quasi-longitudinal design with 270 talented players aged 10-18 years performing the LSPT (661 measurement occasions); multilevel modelling was applied. Secondly, differences between those players allowed to continue in the development program (selected, n=269) and players who were forced to leave (de-selected, n=50) were investigated using independent sample t-tests. The longitudinal data showed that the predicted execution time (i. e., speed) improved approximately 18% from age 10-18 years (P<0.05), skill performance time (i. e., combination of speed and accuracy) was predicted to improve approximately 32% (P<0.05). The second part showed that selected players outscored de-selected players only on skill performance time (P<0.05), not on execution time (P>0.05). In conclusion, in high-level youth soccer, the combination of speed and accuracy in soccer skills might be more important than speed alone.

Cognitive Functions in Elite and Sub-Elite Youth Soccer Players Aged 13 to 17 Years

Soccer players are required to anticipate and react continuously in a changing, relatively unpredictable situation in the field. Cognitive functions might be important to be successful in soccer. The current study investigated the relationship between cognitive functions and performance level in elite and sub-elite youth soccer players aged 13–17 years. A total of 47 elite youth soccer players (mean age 15.5 years, SD = 0.9) and 41 sub-elite youth soccer players (mean age 15.2 years, SD = 1.2) performed tasks for “higher-level” cognitive functions measuring working memory (i.e., Visual Memory Span), inhibitory control (i.e., Stop-Signal Task), cognitive flexibility (i.e., Trail Making Test), and metacognition (i.e., Delis-Kaplan Executive Function System Design Fluency Test). “Lower-level” cognitive processes, i.e., reaction time and visuo-perceptual abilities, were also measured with the previous tasks. ANOVA’s showed that elite players outscored sub-elite players at the “higher-level” cognitive tasks only, especially on metacognition (p < .05). Using stepwise discriminant analysis, 62.5% of subjects was correctly assigned to one of the groups based on their metacognition, inhibitory control and cognitive flexibility performance. Controlling for training hours and academic level, MANCOVA’s showed differences in favor of the elite youth soccer players on inhibitory control (p = .001), and cognitive flexibility (p = .042), but not on metacognition (p = .27). No differences were found concerning working memory nor the “lower-level” cognitive processes (p > .05). In conclusion, elite youth soccer players have better inhibitory control, cognitive flexibility, and especially metacognition than their sub-elite counterparts. However, when training hours are taken into account, differences between elite and sub-elite youth soccer players remain apparent on inhibitory control and cognitive flexibility in contrast to metacognition. This highlights the need for longitudinal studies to further investigate the importance of “higher-level” cognitive functions for talent identification, talent development and performance in soccer.

The changing characteristics of talented soccer players - a decade of work in Groningen

Abstract Talent development programmes for professional soccer clubs aim to guide players towards professional level performance. We identify whether the intermittent endurance capacity of these players may have changed over time. Since the 2000/2001 competition season, the intermittent endurance capacity of players in the talent development programmes of two professional soccer clubs was measured annually. A total of 492 players participated, divided across seven age categories (under 13 (U13), U14, U15, U16, U17, U18, U19) and resulting in 953 measurements. Analyses of variance showed an improvement in intermittent endurance capacity from the 2000/2001 season to 2009/2010 of around 50% in all age groups (P < 0.05). A possible explanation is the increased quantity and quality of training over the years. When identifying, developing and selecting young players, scouts, trainers and coaches have to be aware that the current level of soccer and its underlying performance characteristics – such as intermittent endurance capacity – are improving over time. This factor may have consequences for current young players aiming to make it to the top 10 years from now.

A longitudinal study on gross motor development in children with learning disorders

This longitudinal study examined the development of gross motor skills, and sex-differences therein, in 7- to 11-years-old children with learning disorders (LD) and compared the results with typically developing children to determine the performance level of children with LD. In children with LD (n=56; 39 boys, 17 girls), gross motor skills were assessed with the Test of Gross Motor Development-2 and measured annually during a 3-year period. Motor scores of 253 typically developing children (125 boys, 112 girls) were collected for references values. The multilevel analyses showed that the ball skills of children with LD improved with age (p<.001), especially between 7 and 9 years, but the locomotor skills did not (p=.50). Boys had higher ball skill scores than girls (p=.002) and these differences were constant over time. Typically developing children outperformed the children with LD on the locomotor skills and ball skills at all ages, except the locomotor skills at age 7. Children with LD develop their ball skills later in the primary school-period compared to typically developing peers. However, 11 year-old children with LD had a lag in locomotor skills and ball skills of at least four and three years, respectively, compared to their peers.

Effects of the Fitkids Exercise Therapy Program on Health-Related Fitness, Walking Capacity, and Health-Related Quality of Life

Background Children with disabilities have an increased risk for reduced fitness and reduced health-related quality of life (HRQoL). Fitkids, a nationwide exercise therapy program in the Netherlands, was developed to improve fitness and HRQoL in children with disabilities. Objective The study objective was to determine the effects of the Fitkids program on health-related fitness, walking capacity, and HRQoL in children with disabilities or chronic conditions. Design This was a quasi-experimental single-group longitudinal study. Methods Fifty-two children and adolescents who were referred to the Fitkids program participated in this study. Participants received a graded exercise training program for 6 months, with frequencies of 1 hour 2 times per week in the first 3 months and 1 hour per week during months 4 to 6. Health-related fitness (aerobic fitness, anaerobic fitness, and muscle strength), walking capacity, and HRQoL were evaluated at baseline and after 3 and 6 months of training. Multilevel modeling was used to quantify the contributions of repeated measures, participants, and Fitkids centers to variations in health-related fitness, walking capacity, and HRQoL during the intervention period. The models were adjusted for sex, height, and weight. Results After 6 months of training, significant intervention effects were found for aerobic fitness, anaerobic fitness, and muscle strength. A significant effect also was found for walking capacity. On the HRQoL measure, significant improvements were found for the self-reported and parent-reported physical and emotion domains and for the parent-reported total score for HRQoL. Limitations No control group was included in this study. Conclusions The Fitkids exercise therapy program has significantly improved health-related fitness, walking capacity, and HRQoL in children and adolescents with chronic conditions or disabilities.

Laterality related to the successive selection of Dutch national youth soccer players

ABSTRACT In the general population, estimates of left-foot preference are around 20%. In soccer, specific tasks create positional demands, requiring 40% of the players to be left-footed. Whether and how this is related to the selection of players is unknown. To examine the successive selection of soccer players for Dutch national youth teams in relation to foot preference, 280 youth players (age = 16.2 ± 1.08 years) were monitored from the U16 through the U19 teams over the last 5 years. No difference in successive selection between left- and right-footed players was found (p < 0.05). Regardless of foot preference, more than 50% of the selected players were deselected out of a national youth team after 2 years. On average, 31% of the national youth players were left-footed, which is higher than expected, based on population estimates (χ2 (1) = 37.49, p < 0.001, w = 0.27). However, there was an under-representation of left-footed players, based on expected positional demands (i.e., attack, midfield, defence) (χ2 (1) = 16.83, p < 0.001, w = 0.18). The conclusion is that left-foot preference increases the probability of selection in Dutch national youth soccer teams.

The Dutch Technical-Tactical Tennis Test (D4T) for Talent Identification and Development: Psychometric Characteristics

Abstract This study examined the test-retest reliability, validity and feasibility of the newly developed Dutch Technical-Tactical Tennis Test (D4T). This new test is relevant for talent identification and development in tennis. Thirty-two youth male tennis players (age 13.4 ± 0.5) were classified as elite (n = 15) or sub-elite (n = 17) according to their position on the national youth ranking list under 15 years (cut-off rank 50) in the Netherlands. Games, rallies and different tactical situations (i.e. offensive, neutral and defensive) were simulated with a ball machine. Players had to return 72 balls to predetermined target areas. Stroke quality was recorded based on ball velocity and accuracy (VA-index), as well as percentage errors. Test-retest reliability was assessed by comparing differences between the first and second test-session (n = 10). An intraclass-correlation coefficient of .78 for the VA-index was found (p < .05), indicating excellent test-retest reliability. Independent t-tests revealed that elite players outscored sub-elite players for the VA-index, ball velocity, accuracy and percentage errors (p < .05), supporting good validity. Furthermore, a high correlation was found between the VA-index and individual positions on the youth ranking list (p = -.75; p < .001). The assessment of feasibility indicated that the D4T was applicable for instructors and coaches. In conclusion, the D4T was shown to be a reliable, valid and feasible test to measure technical-tactical characteristics of tennis performance in youth players.