Surveying the youth-to-senior transition landscape in Major League Soccer: a new frontier.

PURPOSE: The aim of this study was to survey Major League Soccer stakeholders' attitudes and perspectives on the youth-to-senior transition with a particular interest in the league's evolving club structures, specifically the reserve team and youth academy entities. The survey assessed various stakeholders' views on clubs' organisational aims and structure, the capabilities of club entities to prepare players for the first team, and the transition process to the first team within MLS. METHODS: A total of 80 participants working in various 'player operation' roles for MLS clubs in the United States and Canada voluntarily completed the online survey. RESULTS: The predominant aim for both reserve teams and academies in MLS is to develop players for the first team. The organisational structure and governance of reserve teams are varied across the league, but an overarching feature is their function as a development team. When players are transitioning, communication between staff may or may not be clear and effective. Finally, for players within an MLS club's talent pathway, a variety of support strategies are made available during the transition into the first team, but psychological support in particular may be limited or unavailable. CONCLUSION: Similar to European soccer, the aim of MLS reserve teams and youth academies is to develop first team players for the club. However, while players are transitioning into the first team, communication may or may not be clear and effective, and psychological support may be absent, which may impair player development initiatives.

Methods to predict the timing and status of biological maturation in male adolescent soccer players: A narrative systematic review.

The aim of this review was to summarise the methods used to predict and assess maturity status and timing in adolescent, male, academy soccer players. A systematic search was conducted on PubMed, Scopus, Web of Science, CINAHL, Medline and SPORTDiscus. Only experimental studies including male, academy players aged U9-U18 years registered with a professional soccer club were included. The methodological quality of the included studies was assessed using guidelines from the Framework of Potential Biases. Fifteen studies fulfilled our inclusion criteria. Studies were mainly conducted in European countries (n = 12). In total, 4,707 players were recruited across all 15 studies, with an age range of 8-18 years. Five studies were longitudinal, two studies were mixed-method designs and eight studies were cross-sectional. Due to high heterogeneity within the studies, a meta-analysis was not performed. Our findings provided no equivalent estimations of adult height, skeletal age, or age at PHV. Discrepancies were evident between actual and predicted adult height and age at PHV. The Bayley-Pinneau [1952], Tanner-Whitehouse 2 [1983] and Khamis-Roche [1994] methods produced estimates of adult height within 1cm of actual adult height. For age at PHV, both Moore [2015] equations produced the closest estimates to actual age at PHV, and the Fransen [2018] equation correlated highly with actual age at PHV (>90%), even when the period between chronological age and age at PHV was large. Medical imaging techniques (e.g., Magnetic Resonance Imaging, X-Ray, Dual energy X-ray Absorptiometry) demonstrated high intra/inter-rater reliability (ICC = 0.83-0.98) for skeletal maturity assessments. The poor concordance between invasive and non-invasive methods, is a warning to practitioners to not use these methods interchangeably for assessing maturational status and timing in academy soccer players. Further research with improved study designs is required to validate these results and improve our understanding of these methods when applied in this target population.

Research in Another un-Examined (RAE) context. A chronology of 35 years of relative age effect research in soccer: is it time to move on?

It is approximately 35 years since the publication of the first relative age effect paper in sport and despite the volume of empirical studies, book chapters, conference presentations, and column inches dedicated to this topic we appear to be no further on in eliminating or attenuating this discriminatory practice. This commentary argues that the ongoing use of univariate methods, focusing on primary or secondary analyses of birth-date data, unearthed from previously un-examined contexts is not conducive to stimulating discussion or providing empirical solutions to relative age effects. This paper concludes by suggesting a departure from the traditionally narrow view of relative age inquiry and instead consider the role of transdisciplinary research.

Efficacy of using non-linear pedagogy to support attacking players' individual learning objectives in elite-youth football: A randomised cross-over trial.

The present study examined the efficacy of a coaching curriculum, based on non-linear pedagogy, on improving attacking players' individual learning objectives (ILOs) in elite-youth football. Participants included 22 attacking players (i.e., centre-forwards, wide-players and attacking midfield players) from a professional football academy in England. The players were randomly appointed to both control (CON) and intervention (INT) periods following baseline measures. The INT (non-linear) and CON (linear) periods were both designed to support the ILOs provided to each player as part of the elite player performance plan. The study adopted a randomised cross-over design and ILOs considered important for attacking players (i.e., strong foot finishing, weak foot finishing, 1-v-1 and decision-making) were evaluated using the Loughborough Shooting Skill Test. The results showed significant differences for INT in 1-v-1 (P< 0.02) and decision-making (P< 0.01). However, there were no significant differences for strong foot finishing, weak foot finishing or time taken. These results support non-linear pedagogy in developing 1-v-1 game play and decision-making but not for technical shooting proficiency.

A bioecological perspective on talent identification in junior-elite soccer: A Pan-European perspective.

Elite soccer clubs across Europe spend ever-increasing sums of money on transfers and salaries for world-class players. Consequently, clubs' talent identification and development processes for junior players have become more professionalised. Based on a holistic ecological approach, this study presents an analysis of talent identification practices across some of the most productive soccer academies in Europe (N = 11). Data were collected via semi-structured interviews with 11 heads of academy recruitment from clubs in the "big five" European leagues. Clubs were purposively sampled based on their player productivity ranking. Interviews ranged from 52:26 minutes to 114:06 minutes in length (m = 87:53 ± 20.10 minutes). This study argues that holistic ecological approaches the environments were characterised through the interplay of factors that ranged from high-level internal to international level relationships. This resulted in the identification and recruitment of players from local and international environments. The purpose of recruitment was suggested to have a dual purpose: recruitment of players for the first team; recruitment of players for further development/monitoring and/or selling to another club.

A case study of the use of verbal reports for talent identification purposes in soccer: A Messi affair!

Using a two-study approach, the main purpose of this case study was to explore the use of a verbal reporting methodology to better understand the thought processes of soccer talent scouts during an in-situ talent identification environment. Study 1 developed a standardized coding-scheme to examine verbal cognitions during a single soccer game. Study 2 then utilized this methodology to examine two full-time recruitment staff trained in the use of concurrent verbal reporting before undertaking a live, in-game task. Participants also participated in a debrief interview following the game. The findings of the two studies suggest that developing a verbal reporting protocol is viable, however when applied in a live-game environment it is problematic. Future research should therefore consider a modified version of this task to further explore the cognitions of scouts whilst observing and identifying potential talent.

Profiling of translational and rotational head accelerations in youth BMX with and without neck brace.

OBJECTIVES: To investigate the influence of BMX helmets and neck braces on translational and rotational accelerations in youth riders. DESIGN: Mixed model, repeated measure and correlation. METHODS: Twenty three competitive youth BMX riders classified by age group (6-9 years, 10-13 years and 14-18 years) completed 6 laps of an indoor BMX track at race pace, 3 laps without a neck brace (NB) and 3 without brace (WB). A triaxial accelerometer with gyroscope was placed behind the right ear to determine the mean number of accelerations, translational and rotational, of the head between conditions and by age group. RESULTS: Significant reductions by condition (p=0.02) and by age (p=0.04) were found for the number of accelerations, though no interactions (condition×age) were revealed. Significant increases by age (p=0.01) were revealed for translational accelerations, whilst significant increases by condition (p=0.02) were found for rotational accelerations. In addition, significant correlations were revealed between relative helmet mass and age (r=0.83; p=0.001) and relative helmet mass and number of accelerations (r=0.46; p=0.03). CONCLUSIONS: Accelerations at the head decreased with increased age, possibly due to the influence of greater stabilising musculature. Additionally, neck braces also significantly reduced the number of accelerations. However, the magnitude of accelerations may be influenced by riding dynamics. Therefore, the use of neck braces combined with strength work to develop neck strength, could aid in the reduction of head accelerations in youth BMX riders.

The Effect of "Pumping" and "Nonpumping" Techniques on Velocity Production and Muscle Activity During Field-Based BMX Cycling.

Rylands, LP, Hurst, HT, Roberts, SJ, and Graydon, RW. The effect of "pumping" and "nonpumping" techniques on velocity production and muscle activity during field-based BMX cycling. J Strength Cond Res 31(2): 445-450, 2017-The aim of the current study was to determine if a technique called "pumping" had a significant effect on velocity production in Bicycle Motocross (BMX) cycling. Ten National standard male BMX riders fitted with surface electromyography (sEMG) sensors completed a timed lap of an indoor BMX track using the technique of pumping, and a lap without pumping. The lap times were recorded for both trials and their surface sEMG was recorded to ascertain any variation in muscle activation of the biceps brachii, triceps brachii, vastus lateralis, and medial gastrocnemius. The findings revealed no significant differences between any of muscle groups (p > 0.05). However, significant differences (p < 0.001) were observed between the pumping and nonpumping trials for both mean lap velocity (42 ± 1.8 km·h, 33 ± 2.9 km·h, respectively) and lap times (43.3 ± 3.1 seconds, 34.7 ± 1.49 seconds, respectively). The lap times recorded for the pumping trials were 19.50 ± 4.25% lower than the nonpumping, whereas velocity production was 21.81 ± 5.31% greater in the pumping trial compared with the nonpumping trial. The technique of pumping contributed significantly to velocity production, although not at the cost of additional muscle activity. From a physiological and technical perspective, coaches and riders should prioritize this technique when devising training regimes.

Effect of cadence selection on peak power and time of power production in elite BMX riders: A laboratory based study.

The aims of this study were to analyse the optimal cadence for peak power production and time to peak power in bicycle motocross (BMX) riders. Six male elite BMX riders volunteered for the study. Each rider completed 3 maximal sprints at a cadence of 80, 100, 120 and 140 revs · min-1 on a laboratory Schoberer Rad Messtechnik (SRM) cycle ergometer in isokinetic mode. The riders' mean values for peak power and time of power production in all 3 tests were recorded. The BMX riders produced peak power (1105 ± 139 W) at 100 revs · min-1 with lower peak power produced at 80 revs · min-1 (1060 ± 69 W, (F(2,15) = 3.162; P = .266; η2 = 0.960), 120 revs · min-1 (1077 ± 141 W, (F(2,15) = 4.348; P = .203; η2 = 0.970) and 140 revs · min-1 (1046 ± 175 W, (F(2,15) = 12.350; P = 0.077; η2 = 0.989). The shortest time to power production was attained at 120 revs · min-1 in 2.5 ± 1.07 s. Whilst a cadence of 80 revs · min-1 (3.5 ± 0.8 s, (F(2,15) = 2.667; P = .284; η2 = 0.800) 100 revs · min-1 (3.00 ± 1.13 s, (F(2,15) = 24.832; P = .039; η2 = 0.974) and 140 revs · min-1 (3.50 ± 0.88 s, (F(2,15) = 44.167; P = .006; η2 = 0.967)) all recorded a longer time to peak power production. The results indicate that the optimal cadence for producing peak power output and reducing the time to peak power output are attained at comparatively low cadences for sprint cycling events. These findings could potentially inform strength and conditioning training to maximise dynamic force production and enable coaches to select optimal gear ratios.

Effect of gear ratio on peak power and time to peak power in BMX cyclists.

The aim of this study was to ascertain if gear ratio selection would have an effect on peak power and time to peak power production in elite Bicycle Motocross (BMX) cyclists. Eight male elite BMX riders volunteered for the study. Each rider performed three, 10-s maximal sprints on an Olympic standard indoor BMX track. The riders' bicycles were fitted with a portable SRM power meter. Each rider performed the three sprints using gear ratios of 41/16, 43/16 and 45/16 tooth. The results from the 41/16 and 45/16 gear ratios were compared to the current standard 43/16 gear ratio. Statistically, significant differences were found between the gear ratios for peak power (F(2,14) = 6.448; p = .010) and peak torque (F(2,14) = 4.777; p = .026), but no significant difference was found for time to peak power (F(2,14) = 0.200; p = .821). When comparing gear ratios, the results showed a 45/16 gear ratio elicited the highest peak power,1658 ± 221 W, compared to 1436 ± 129 W and 1380 ± 56 W, for the 43/16 and 41/16 ratios, respectively. The time to peak power showed a 41/16 tooth gear ratio attained peak power in -0.01 s and a 45/16 in 0.22 s compared to the 43/16. The findings of this study suggest that gear ratio choice has a significant effect on peak power production, though time to peak power output is not significantly affected. Therefore, selecting a higher gear ratio results in riders attaining higher power outputs without reducing their start time.

Variability in Laboratory vs. Field Testing of Peak Power, Torque, and Time of Peak Power Production Among Elite Bicycle Motocross Cyclists.

The aim of this study was to ascertain the variation in elite male bicycle motocross (BMX) cyclists' peak power, torque, and time of power production during laboratory and field-based testing. Eight elite male BMX riders volunteered for the study, and each rider completed 3 maximal sprints using both a Schoberer Rad Messtechnik (SRM) ergometer in the laboratory and a portable SRM power meter on an Olympic standard indoor BMX track. The results revealed a significantly higher peak power (p ≤ 0.001, 34 ± 9%) and reduced time of power production (p ≤ 0.001, 105 ± 24%) in the field tests when compared with laboratory-derived values. Torque was also reported to be lower in the laboratory tests but not to an accepted level of significance (p = 0.182, 6 ± 8%). These results suggest that field-based testing may be a more effective and accurate measure of a BMX rider's peak power, torque, and time of power production.

The influence of relative age effects on the cardiorespiratory fitness levels of children age 9 to 10 and 11 to 12 years of age.

The aims of this study were firstly to examine whether there was an observed relative age effect in the cardiorespiratory fitness scores of 9-10 and 11-12 year old children, and secondly whether any observed effect was maintained after controlling for somatic maturity. Cardiorespiratory fitness data from 11,404 children aged 9-10 years and 3,911 children aged 11-12 years were obtained from a large cross-sectional field-based fitness testing program. A one-way ANOVA revealed a statistically significant relative age effect (p < .01) existed in the 20mSRT scores across all the age groups. Furthermore, ANCOVA analyses identified a statistically significant relative age effect was maintained after controlling for somatic maturation (p < .05). From a public health perspective these results confirm the existence of relative age effects for the first time and consequently may hold implications for relatively younger children in the accurate assessment of their cardiorespiratory fitness scores.

Diffusion of biologically relevant molecules through gel-like tissue scaffolds.

Encapsulation of living cells into gel-like matrices that are capable of maintaining their viability over an extended time period is starting to play a major role in medicine in applications such as, cell-based sensors, cellular therapy, and tissue engineering. The permeability of nutrients and waste products through these matrices is critical to their performance. In this article, we report a methodology for selecting scaffolds with different permeabilities and surface area/volume ratios that can be used to house a 3D cell aggregate. Such a system can be modeled if the consumption or production rates for metabolites and waste products, respectively and the diffusion coefficients of these solutes in culture medium and the encapsulating gel matrix are known. A transient finite volume mass diffusion model, based on Fick's law, is derived where the consumption of a solute by the cells is modeled through a source term. The results show that the "performance" of cell-doped gel is critically dependent on the rate at which cells consume key molecules e.g., glucose. Pragmatically, the model also provides insight as to how many cells a given gel geometry and structure can support. The approach used applies to any porous structure where mass transport occurs through diffusion.