Mature Players Research Articles

Relationship between bilateral humeral retroversion angle and starting baseball age in skeletally mature baseball players—existence of watershed age

Repetitive pitching in childhood was thought to restrict the physiological derotation process of the humeral head. Some studies reported that the side-to-side differences of humeral retroversion in baseball players occurred between the age of 9 and 11 years. The present study investigated the relationship between bilateral humeral retroversion angle and starting baseball age in skeletally mature baseball players. One hundred and seventeen male baseball players, who belonged to a college or amateur team, were investigated. Bilateral humeral retroversion was assessed using an ultrasound-assisted technique as described by previous studies. All players were divided into four groups: players who had started playing baseball before the age of 6 years, between 7 and 8 years, between 9 and 10 years and after 11 years. Bilateral humeral retroversion angle was compared among the four starting age groups. All players started playing baseball between 5 and 12 years. Comparing the throwing arm, humeral retroversion in starting age group 11-12 (72°) was significantly smaller than the other 3 groups (81°, 82°, and 80° for groups 5-6, 7-8, and 9-10, respectively). Comparing the non-throwing arm revealed no significant differences among the 4 starting age groups (71°, 72°, 70°, and 66° for groups 5-6, 7-8, 9-10, and 11-12, respectively). Skeletally mature baseball players who started playing baseball after 11 years had significantly smaller humeral retroversion in the throwing arm than those who started baseball before 11 years.

Physical Characteristics of Elite Youth Female Soccer Players Characterized by Maturity Status.

Emmonds, S, Scantlebury, S, Murray, E, Turner, L, Robsinon, C, and Jones, B. Physical characteristics of elite youth female soccer players characterized by maturity status. J Strength Cond Res 34(8): 2321-2328, 2020-The purpose of this study was to investigate the influence of maturity status on the physical characteristics of youth female soccer players. One hundred fifty-seven players from 3 elite soccer academies in England completed assessments of anthropometry, strength (isometric midthigh pull), lower-body power (countermovement jump [CMJ]), aerobic capacity (Yo-Yo intermittent recovery test level 1), change of direction (CoD: 505-left/right), and speed (10 and 30 m). Each player was classified into 1 of 6 maturity groups based on their estimated years from peak height velocity (YPHV). Magnitude-based inferences were used to assess for the practical significance between consecutive groups. Speed, CoD time, CMJ, and aerobic capacity were all possibly most likely better in more mature players. However, there was a likely difference in relative peak force between maturity groups -0.5 YPHV (27.13 ± 4.24 N·Kg) and 0.5 YPHV (24.62 ± 3.70 N·Kg), which was associated with a likely difference in 10-m sprint time (-0.5 YPHV: 2.00 ± 0.12 vs. 0.5 YPHV 2.08 ± 0.16 seconds) and unclear changes in CMJ and CoD time. Findings provide novel comparative data for this cohort relative to maturity status and can be used by strength and conditioning coaches to inform the design of training programs for youth female soccer players. Strength and conditioning coaches should be aware that youth female soccer players may experience a decrease in relative strength around peak height velocity, which may impact upon the speed, CoD time, and CMJ of players.

Left-handed skeletally mature baseball players have smaller humeral retroversion in the throwing arm than right-handed players

It is known that the humeral retroversion of baseball players is greater in the throwing arm than in the nonthrowing arm. An investigation measuring dry bone specimens also showed that the right humerus had greater retroversion than the left. Considering these facts, it was hypothesized that humeral retroversion would differ between right- and left-handed players. This study aimed to compare the bilateral humeral retroversion between right- and left-handed skeletally mature baseball players. We investigated 260 (196 right-handed and 64 left-handed) male baseball players who belonged to a college or amateur team. Bilateral humeral retroversion was assessed using an ultrasound-assisted technique (humeral torsion angle [HTA]) as described by previous studies. Analysis of covariance, adjusted for handedness and baseball position, assessed the effect of throwing arm dominance on HTA. In comparison of the throwing arm, HTA was significantly smaller in left-handed (left humerus) than in right-handed (right humerus) players (77° vs. 81°; P < .001). In comparison of the nonthrowing arm, HTA was significantly greater in left-handed (right humerus) than in right-handed (left humerus) players (73° vs. 69°; P < .001). The mean side-to-side difference of HTA was significantly smaller in left-handed than in right-handed players (3° vs. 12°; P < .001). Humeral retroversion of left-handed skeletally mature baseball players was significantly smaller in the throwing arm, greater in the nonthrowing arm, and smaller in side-to-side differences than that of right-handed players. These findings may be key to understanding some of the biomechanical differences between right- and left-handed baseball players.

Longitudinal change in patellofemoral cartilage thickness, cartilage T2 relaxation times, and subchondral bone plate area in adolescent vs mature athletes

ObjectivePatellofemoral cartilage changes have been evaluated in knee trauma and osteoarthritis; however, little is known about changes in patellar and trochlear cartilage thickness, T2 relaxation-time and subchondral bone plate area (tAB) during growth. Our prospective study aimed to explore longitudinal change in patellofemoral cartilage thickness, T2 and tAB in adolescent athletes, and to compare these data with those of mature (i.e., adult) athletes. Materials and methods20 adolescent (age 16±1years) and 20 mature (46±5years) volleyball players were studied over 2-years (10 men and 10 women each group). 1.5T MRI 3D-VIBE and multi-echo spin-echo sequences were acquired at baseline and 2-year follow-up. Using manual segmentation and 3D reconstruction, longitudinal changes in patellar and trochlear cartilage thickness, patellar cartilage T2 (mono-exponential decay curve with five echoes [9.7–67.9ms]), and patellar and trochlear tAB were determined. ResultsThe annual increase in both patellar and trochlear cartilage thickness was 0.8% (95% confidence interval [CI] 0.6, 1.0) and 0.6% (0.3, 0.9), for adolescent males and females respectively; the longitudinal gain in patellar and trochlear tAB was 1.3% (1.1, 1.5) and 0.5% (0.2, 0.8), and 1.6% (1.1, 2.2) and 0.8% (0.3, 0.7) for adolescent males and females, respectively (no significant between-sex differences). Mature athletes showed smaller gains in tAB, and loss of <1% of cartilage thickness annually. While no significant sex-differences existed in adolescent patellar T2 changes, mature males gained significantly greater T2 than mature females (p=0.002–0.013). ConclusionsPatellar and trochlear cartilage thickness and tAB were observed to increase in young athletes in late adolescence, without significant differences between sexes. Mature athletes displayed patellar cartilage loss (and T2 increases in mature males), potentially reflecting degenerative changes.

Radiological analysis of the medial epicondyle in the adolescent throwing athlete.

Injuries to the medial structures of the elbow due to overhead throwing games are well documented. However, variations of medial epicondyles are not well described, especially in athletes with fused medial epicondyles. In this study, we evaluated variations in the medial epicondyle of baseball players who were aged 15-17 years and had fused epicondyles. In this cross-sectional observational study, 155 skeletally mature baseball players with unilateral medial elbow pain and 310 elbow radiographs were reviewed by two independent reviewers. The medial epicondyles were categorised into three groups: normal, elongated or separated. Among the 155 patients, 65 (41.9%) had normal epicondyles, 41 (26.5%) had elongated epicondyles and 49 (31.6%) had separated epicondyles. The medial epicondyle was larger on the dominant arm for 125 (80.6%) patients; the mean surface area on the dominant arm was 222.50 ± 45.77 mm2, while that of the non-dominant arm was 189.14 ± 39.56 mm2 (p < 0.01). Among the three categories of medial epicondyles, separated epicondyles had the largest surface area, followed by elongated and normal epicondyles. Medial epicondyles in adolescent throwing athletes can be categorised into three different groups according to their shape (normal, elongated and separated). We observed a correlation between the shape and the surface area of the medial epicondyle in adolescent throwing athletes, with separated medial epicondyles having the largest surface area. Further studies and follow-up are needed to determine the prognostic value and clinical significance of these morphological variations.

Examination of group cohesiveness levels and goal orientations of basketball players

This research intends to examine goal orientation and group cohesiveness levels of basketball players. 243 mature players who play in the leagues of Turkish Basketball Federation in 2016- 2017 season participated the study. “Task and Ego Orientation in Sports” and “Group Cohesiveness” questionnaires are used in study. While frequency, arithmetic mean and standard deviation is used for the analysis of data, T-Test, One-Way Analysis of Variance (ANOVA) and Post-Hoc test statistics (Tukey HSD) are used for independent samples. Depending on the variables of gender and educational background of players, a significant difference is identified in sub-dimension of Task Attraction of Group and a low-level negatively significant difference is identified between Ego Orientation in terms of age and sportive age. Significant differences are identified between the Perception of Team Success and sub-dimensions of Social Integration of Group and Social Attraction of Group. No statistically significant difference can be found for the variable of time spent in team in terms of group cohesiveness and goal orientation.

Physical Maturity and Concussion Symptom Duration among Adolescent Ice Hockey Players

To investigate the association between physical maturity and risk of prolonged concussion symptoms in adolescent ice hockey players. Prospective cohort study of 145 patients ages 13-18 years with concussion referred to 3 hospital-affiliated sports medicine clinics between September 1, 2012 and March 31, 2015. Concussion evaluations included Post Concussive Symptom Score, neurologic examination, and postinjury computerized neurocognitive testing. Pubertal development at initial visit was assessed by the Pubertal Developmental Scale. Duration of concussion symptoms (days) was the main outcome. Statistical comparisons were conducted using Student t test, Wilcoxon rank sum, and logistic regression. Mean symptom duration was 44.5 ± 48.7 days. Nearly one-half (48.3%) of all players enrolled had prolonged concussion symptoms (≥ 28 days); most (86.9%) had symptom resolution by 90 days. Among males, less physically mature adolescents took longer to recover than more physically mature players (54.5 days vs 33.4 days; P = .004). "Early" Pubertal Category Score was the strongest predictor of prolonged symptoms (OR = 4.29, 95% CI 1.24-14.85; P = .021) among males. Among females, heavier weight increased the odds of experiencing prolonged symptoms (OR 1.07, 95% CI 1.00-1.14; P = .039). Among adolescent ice hockey players, early-pubertal stage is independently associated with longer recovery from concussion in males, and heavier weight is associated with longer concussion recovery in females. Until further studies determine valid physical maturity indicators, peripubertal collision sport athletes should compete in leagues grouped by relative age and be discouraged from "playing up" on varsity teams.

Toys as Tools for Skill-building and Creativity in Adult Life

Previous understandings of adult use of toys are connected with ideas of collecting and hobbying, not playing. This study aims to address toys as play objects employed in imaginative scenarios and as learning devices. This article situates toys (particularly, character toys such as Blythe dolls) as socially shared tools for skill-building and learning in adult life. The interviews with Finnish doll players and analyses of examples of their productive, toy-related play patterns showcased in both offline and digital playscapes reveal how toy play leads to skill-building and creativity at a mature age.The meanings attached to and developed around playthings expand purposely by means of digital and social media. (Audio)visual content-sharing platforms, such as Flickr, Pinterest, Instagram and YouTube, invite mature audiences to join playful dialogues involving mass-produced toys enhanced through do-it-yourself practices. Activities circulated in digital play spaces, such as blogs and photo management applications, demonstrate how adults, as non-professional ‘everyday players’, approach, manipulate and creatively cultivate contemporary playthings. Mature players educate potential players by introducing how to use and develop skills by sharing play patterns associated with their playthings. Producing and broadcasting tutorials on how to play creatively with toys encourage others to build their skills through play.

Relative Age Effects in Welsh Age Grade Rugby Union

Relative age effect (RAE) refers to the immediate and long-term consequences of age difference within an age grouping. In sporting contexts, it has been widely shown that those born in the first quarter gain an advantage over those born in the last quarter of the year. Rugby Union has received scant attention in relation to RAE. The primary purpose of the present study was to examine the presence and prevalence of RAE in Welsh age grade Rugby Union. A further purpose was to consider how coaches' selection processes have the potential to contribute to the manifestation of RAE. A sequential multi-method research typology was adopted to gain a richer, more contextualized understanding of RAE. Results revealed that RAE was evident in all age groups of Welsh junior club rugby from ‘Under 7–19 yrs'. Odds ratios showed that the magnitude of the RAE increases with the three levels of performance (district, regional and national) above the club game. Further, the process of selection had characteristics that increased the risk of RAE occurring, especially a propensity to use physical characteristics as the primary selection criteria when selecting for representative teams. Also, coaches' overemphasis on game performance and winning appeared to determine that the older, potentially bigger, faster, stronger players are preferred over the younger less physically mature players.

An Analysis of China's Outward Foreign Direct Investment to the EU: Features and Problems

Abstract This research paper reviews the development of China's outward foreign direct investment (OFDI) to the European Union since the global fnancial crisis, summarizes the apparent characteristics and causes behind that development, provides an in-depth analysis of the problems and deep rooted risks in such investment, and predicts that with China's economy being stronger the scale of China's OFDI will be greater in the coming period. However, since Chinese enterprises are really newcomers of OFDI, they are far from being mature and successful players, which requires not only capital, but also an organic combination of intangible elements regarding economy, society, and culture etc.

Relative age effects in Australian Football League National Draftees

This study examined the birth distribution for adolescent (i.e. <20 years) and mature age players (i.e. ≥20 years) selected in the Australian Football League (AFL) National Draft between 2001 and 2012. Birth-date information was accessed for all first time AFL national draftees and players were then classified as either adolescent (N = 736) or mature age (N = 70) draftees. Chi-squared analysis showed a clear bias in the birth distribution of adolescent draftees towards players born in the first part of the classification period for both quartile (P < 0.001) and half-year (P < 0.001) compared to the Australian national population. There was a reverse relative age effect (RAE) for mature age draftees, with a significant bias towards players born in the latter part of the selection period for both quartile (P = 0.047) and half-year (P = 0.028) compared to the Australian national population. The selection bias towards relatively older players in adolescent AFL draftees may be related to advanced physical and psychological maturity, and exposure to higher-level coaching compared to their younger counterparts. The reverse RAE in mature age draftees is a novel finding and supports the need for strategies to encourage continued participation pathways for talented Australian football players born later in the selection year.

Interpretation of peak oxygen consumption in 10–12-year-old soccer players: effect of biological maturation and body size

The aim of this study was to investigate the effect of biological maturation and body size on aerobic capacity using appropriate scaling procedures in 10–12-year-old soccer players divided into late, average and early maturing boys. Peak oxygen consumption (VO 2 peak) was expressed as absolute values, ratio standards, theoretical exponents and experimentally observed exponents. VO 2 peak was not directly proportional to body mass as the experimentally observed exponent for body mass calculated through linear regression analysis yielded to b=0.64 (R 2 =0.62; p2peak expressed in l/min was different (p2peak values were adjusted for body mass (ml/min/kg), or when the effect of body mass was adjusted for using theoretical exponent scales (ml/kg 0.67 /min, ml/kg 0.75 /min) and experimentally observed exponent (ml/kg 0.64 /min), the VO 2 peak responses displayed relativeley constant values (p>0.05) throughout different maturation groups. Linear regression analyses indicated that after adjusting for the effects of body mass using the theoretical exponent scales (ml/min/kg 0.67 ), biological maturation and body size had no effect on VO 2 peak values in young soccer players. In conclusion, the theoretical exponent scale for body mass (ml/kg 0.67 /min) control adequately for biological maturation and body size differences in VO 2 peak in 10–12-year-old soccer players. Therefore, more mature soccer players with better body size values should not be preferentially selected for young soccer teams.

Biological maturity influences running performance in junior Australian football

ObjectivesThe purpose of this study was to investigate the influence of biological maturity on measures of running fitness and running performance in both training and competition in junior Australian football. DesignCross sectional observational. MethodsFifty-two male junior players from five age groups (U11–U19) participated. Biological maturity was self-assessed based on Tanner's description of five pubertal stages (P1–P5) as well as objectively estimated from anthropometric measures and expressed as years to and from peak height velocity (Y-PHV). Running speed and aerobic fitness were measured using a 20m sprint and 20m multi-stage shuttle run respectively. Running movements during training and competition were analysed (n=197) using global positioning system technology, including total distance, peak speed, high-intensity running (HIR>14.4km/h) distance and number of sprints (>23km/h). ResultsAge groups included participants from a range of pubertal stages (U11: P1–2; U13: P2–4; U15: P2–5; U17: P4–5; U19: P5). Y-PHV was significantly correlated with 20m shuttle run (r=0.647), 20m sprint time (r=−0.773) and all distance and high intensity running variables (r=0.417–0.831). Incremental improvements across pubertal stages for speed, aerobic fitness and most GPS derived running variables were observed. Within age group comparisons between less and more mature players found significant differences for standing and sitting height, peak speed in training, and total distance, HIR and peak speed in matches. ConclusionsFunctional running fitness and running performance in both training and competition environments improved with increasing biological maturity. More mature players in an age group, either chronologically, biologically or a combination of both, are at a performance advantage to those less mature.

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)

We report the morphology (height, weight, body fat, body mass index), fitness (strength, speed, agility, flexibility), and soccer-specific (dribbling) and non-specific motor coordination skills (Körper KoordinationsTest für Kinder; KTK) of 78 Belgian international youth soccer players aged 15–16 years with varying biological maturity status. The more mature players (U16 and U17) possessed higher morphological measures and outperformed their later maturing peers (U16 Futures and U17 Futures) on almost all fitness tests. However, soccer-specific and non-specific motor coordination tests did not distinguish the more mature players from the later maturing players in both age groups. When adjusted for the confounder (age at peak height velocity), multivariate analysis of covariance revealed that several morphology- and fitness-related parameters did not differ between selection groups, again in both age groups. These findings indicate that biological maturation affects morphology and fitness more so than motor coordination skills. In conclusion, to prevent the dropout of promising late maturing players, we suggest avoiding one-dimensional approaches and to include measures of biological maturity status as well as maturity independent performance tests during the talent identification and selection process.

NOBOX does right for the follicle reserve: insights into premature ovarian failure

Investing in the future takes on much more than a financial undertone when one is dealing with the currency of reproduction, our gametes. Whether the perspective is that of the male with its constitutive assembly line turning out many millions of new sperm on an hourly basis or that of the female, with a cautious and methodical rate of consumption at each ovulation, gamete supply and demand principles are at the core of our reproductive capacity. Finding replacements for these specialized cells has yet to be realized despite claims to the contrary regarding the ability of embryonic stem cells to generate sperm or oocyte-like cells. This challenge in part reduces to our ignorance as to the key genes that dictate the process of gametogenesis in the ovary or testis and the complete failure to fully appreciate that like real estate-location, location, location nurses the potential of germ cells to take on the character of their mature products and players in the choreography of fertilization and embryogenesis. Over and above the wonderment of gametogenesis that has attracted the attention of scientists since the advent of microscopy, the clinical reality for those treating infertility disorders of many kinds is that in too many circumstances, the number or quality of gametes produced is compromised. Not insignificant among these disorders is the case of premature ovarian failure (POF). POF in its various forms displays the common attributes of complete follicle loss after birth and the replacement of follicles by fibrotic tissue in the ovary. Some years ago, led by the studies of Rajkovic and colleagues, a gene was discovered and accorded the name NOBOX to represent the fact that it was of the homeobox gene family and expressed in the newborn ovary, specifically in oocytes. It has since become appreciated that NOBOX is a master regulator of key oocyte genes in mice and when “knocked out” results in POF. Moreover, there is now evidence that misregulation of the NOBOX homeodomain occurs in women with POF, implicating this gene among others in the etiology of POF. What is not clear is when this gene imparts the signal for follicular demise and how is it that lesions in NOBOX lead to the gradual elimination of the follicle reserve? The paper by Kloc and colleagues in this issue of JARG takes a major step in improving our understanding of the pathogenesis of POF in humans. Recognizing the expression pattern for NOBOX was confined to the earliest stages of follicle assembly in the newborn mouse ovary, this work took advantage of electron microscopy to analyze the nature of somatic cell and germ cell interactions. The results demonstrate a defect in the ability of somatic granulosa cell progenitors to encase individual oocytes as the process of germ cell cyst breakdown proceeds. Instead, without NOBOX clusters of oocytes are only partially enclosed resulting in the formation of polyovular follicles. In addition, signs of abnormal cell cell interactions are in evidence suggesting that the cell specific recognition and adhesion properties required during follicle assembly have been abrogated in a fashion that spells demise of these abnormal follicles early in postnatal life. This work emphasizes the importance of initiating and maintaining a dialogue between somatic cells and the oocyte from the very inception of the primordial follicle pool. We have long come to appreciate the essential role that supporting granulosa cells play in the support of oogenesis through both the growth and maturative phases. But relatively little has been known about the primal forms of cell communication that set aside what will be the life long reservoir of follicles required to support fertility in adult life. While studies of this kind will continue to rely upon genetically tractable models such as the mouse, gaining insights into the genetic basis of such fundamental processes shapes approaches that could be brought to bear on human investigations. It should come as no surprise that carrying out the dialogue between gonadal somatic cells and germ cells over the duration of gametogenesis is a trademark of successful reproduction in both the testis and the ovary. Perhaps recognizing this essential feature of gametogenesis will guide future studies into the area of stem cell derived germ cells since afterall, it has worked well for Mother Nature.

Perception of Risks Associated with the Doping Use Among the Competitors Practicing Individual and Group Sport Disciplines

Perception of Risks Associated with the Doping Use Among the Competitors Practicing Individual and Group Sport Disciplines Introduction. The aim of this study was the research among athletes whether and to what extent the sport discipline practiced (individual or team competition) influences the perception of risk associated with the use of doping in sport, and whether age and experience translates into the sports perception of the risks of doping. Material and methods. Three groups of athletes diverse was studied because of the nature of the sport task and the experience/time of practice. Individual disciplines were represented by combat sports (n=12, average time of practice ~6 years), group games by football players (n=9, average time of practice ~7 years) and volleyball players (n=13, average time of practice ~14 years.) The technique "Perception of risk of doping" was used to measure: a) the ranking of values that one can afford to lose in consequences of doping; b) the real probability of losing cherished values; c) personally acceptable level of risk associated with loss of value. Results. It was shown that young players who are members of the team are less mature and aware of the risks associated with the use of doping, not only from their older colleagues in the team, but also from their peers, competing individually. In the perception of young players there were both errors in risk assessment (distortion of losses) as well as illusions relating to the control of hazards, and unrealistic optimism about the possibility of avoiding the negative effects of doping. For mature players, the fear of losing public image has proven to be a strong deterrent against the temptation to use of illegal drugs; for young players, a relatively stronger remedy was the fear of losing the attributes of health and physical attractiveness. Conclusion. Due to the small size of the groups, these findings are suggestions that may serve as an inspiration for research on the wider population.

Relationship between training-playing loads and injury risk in elite australian footballers

BackgroundTraining and match loads are important for ensuring optimal performance outcomes and achievements of footballers and also have an impact on injury and illness among the players. There had been...

Study on Chinese and European automotive R&D – comparison of low cost innovation versus system innovation

Chinese carmakers are leapfrogging innovation by levering electric vehicle propulsion technologies and providing low cost solutions. This has become a severe threat for mature global players. On the other hand, European premium carmakers have been able to increase their penetration in emerging markets. Even though premium cars yield higher costs of innovation and offer few possibilities to achieve scale effects, sales have skyrocketed to a record high in 2011. In both cases, manufacturers who can innovate best will emerge as winners in lucrative and expanding markets - regardless of origin or innovation approach. The aim of this paper is to outline disruptive innovation patterns of the Chinese automotive industry and to showcase the system integration capabilities of European carmakers. The paper commences with “the China Price” advantage that plays a vital role for Chinese carmakers to leapfrog technology gaps. It allows offering innovation at low cost. Also, the local electric vehicle supply chain, government supportiveness and behavior of emerging consumer groups drive growth for new technologies such as electric vehicles in China. Next, the European car industry is characterized with the evolution of key innovations coming to a large extend from German premium carmakers. Consequently, the paper shows how their global success and innovation dominance in the premium segment can be linked to their integrated R&D approach. This comprises system development, modularity concepts, in-house R&D value chain, rigorous planning processes and so forth. In summary, the paper analyses key trends in innovation patterns from the Chinese and European car industry. Furthermore, it shows related market drivers such as regulatory development and consumer behavior. At last, a generic model for new product development is used to compare automotive R&D approaches between China and Europe. The authors conclude with their findings on comparing low cost innovation versus system innovation based on Chinese and European automotive R&D.

Size and Maturity Mismatch in Youth Soccer Players 11- to 14-Years-Old

The purpose of the study was to compare the anthropometric, functional and sport-specific skill characteristics and goal orientations of male youth soccer players at the extremes of height and skeletal maturity in two competitive age groups, 11-12 and 13-14 years. The shortest and tallest players, and least and most skeletally mature players (n = 8 per group) within each age group were compared on chronological age; skeletal age (Fels method); pubertal status (pubic hair); size, proportions and adiposity; four functional capacities; four soccer-specific skills; and task and ego orientation. The tallest players were older chronologically, advanced in maturity (skeletal, pubertal) and heavier, and had relatively longer legs than the shortest players in each age group. At 11-12 years, the most mature players were chronologically younger but advanced in pubertal status, taller and heavier with more adiposity. At 13-14 years, the most mature players were taller, heavier and advanced in pubertal status but did not differ in chronological age compared with the least mature players. Players at the extremes of height and skeletal maturity differed in speed and power (tallest > shortest; most mature > least mature), but did not differ consistently in aerobic endurance and in soccer-specific skills. Results suggested that size and strength discrepancies among youth players were not a major advantage or disadvantage to performance. By inference, coaches and sport administrators may need to provide opportunities for or perhaps protect smaller, skilled players during the adolescent years.

Skeletal Age in Youth Soccer Players: Implication for Age Verification

To evaluate variation in skeletal age (SA) within single-year chronological age (CA) groups of soccer players aged 11 to 17 years in the context of using SA for age verification in age-group competitions. Cross sectional. Regional and elite youth soccer programs. Five hundred ninety-two male players from Portugal and Spain. Skeletal age assessed with the Fels method. Skeletal age and maturity status (late, average, early, or mature). Chronological age and SA overlapped in players aged 11 to 12 years, but SA was advanced relative to CA in players aged 14 to 16 years. The majority of players between 11 and 12 years of age were on time in skeletal maturity and percentages of late and early maturers did not differ. The majority of players between 13 and 14 years of age were also on time, but early maturers were 4 times more frequent than late maturers. Percentages of late maturers were low among players aged 14 to 16 years. Among 200 players aged 15 to 16 years, 80 (40%) were advanced in SA by > 1 year and 27 (14%) were skeletally mature, whereas among 23 players aged 17 years, 9 (39%) were skeletally mature. Among adolescent soccer player, boys advanced in SA for CA are overrepresented and those later in SA for CA are underrepresented with increasing CA. If Fels SA was used to verify CA in this sample of youth for under-17 competition, 36 skeletally mature players aged 15 to 17 years (16%) would be disqualified. The results for this sample of male soccer players question the utility of SA or magnetic resonance imaging as a valid estimate of CA in youth sport competitions.