The role of community in the development of elite handball and football players in Denmark

The primary purpose of this study was to investigate the effect of the place of early development in a sample of Danish male elite and youth handball and football players. The sample included 366 handball and football players from the elite Danish league in the season 2011–2012 and a comparison sample of youth players under the age of 12 from 2003, including 147,221 football and 26,290 handball players. Odds ratio analysis showed that both population size and density significantly affected the proportional number of youth players per community and the odds of athletes reaching an elite level in football and handball. The odds for youth player registrations in both handball and football increased in rural in contrast to urban communities. However, elite football players primarily came from communities of high density (>1000 pop./km²), whereas elite handball players primarily came from less densely populated communities (100 to <250 pop./km²). Furthermore, there seems to be a relation between representation of elite and talent clubs in different communities and the probability of becoming an elite player in both sports. The limited number of elite players in both sports from rural communities may be due to national talent development strategies that do not incorporate development support for clubs in rural areas. Additionally, the results of the study clearly suggest the need to include the youth player population to advance research findings in birthplace effect studies.     

When "where" is more important than "when": birthplace and birthdate effects on the achievement of sporting expertise

In this study, we assessed whether contextual factors related to where or when an athlete is born influence their likelihood of playing professional sport. The birthplace and birth month of all American players in the National Hockey League, National Basketball Association, Major League Baseball, and Professional Golfer's Association, and all Canadian players in the National Hockey League were collected from official websites. Monte Carlo simulations were used to verify if the birthplace of these professional athletes deviated in any systematic way from the official census population distribution, and chi-square analyses were conducted to determine whether the players' birth months were evenly distributed throughout the year. Results showed a birthplace bias towards smaller cities, with professional athletes being over-represented in cities of less than 500,000 and under-represented in cities of 500,000 and over. A birth month/relative age effect (in the form of a distinct bias towards elite athletes being relatively older than their peers) was found for hockey and baseball but not for basketball and golf. Comparative analyses suggested that contextual factors associated with place of birth contribute more influentially to the achievement of an elite level of sport performance than does relative age and that these factors are essentially independent in their influences on expertise development.     

Seeing the forest but not the trees: Heterogeneity in community size effects in Canadian ice hockey players

The community size effect (or birthplace effect) suggests that high-performance athletes are less likely to emerge from regions with population sizes that are very small or very large. However, previous research on elite Canadian ice hockey players has not considered the influence of intra-national regional variation of population distributions with respect to community size effects. Therefore, the purpose of the current study was to test the heterogeneity of the community size effect between Canadian National Hockey League draftees (2000–2014: n = 1505), from 7 provincial regions within Canada (i.e., British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec and the Atlantic Provinces). The proportion of athletes in the 9 census population categories were compared to the national and regional general population distributions in the census categories. Results suggest variability of community size effects between the 7 provincial regions within Canada, with only the province of Ontario demonstrating a community size effect congruent with effects reported in previous research. Using regional general population distributions as the comparator to athlete populations changed the direction, meaningfulness and magnitude of community size effects. In conclusion, elite ice hockey player community size effects may not be generalisable to all regions within Canada.     

第十二届男排世界杯各队得分最多队员的主要技术特征分析

运用文献资料法、录像分析法、数理统计法等方法,对第十二届男排世界杯得分最多的球员在比赛中发球、接发球、拦网、扣球等方面的数据进行分析,得出如下结论:(1)本届男排世界杯得分最多队员的各种基本情况;(2)跳发大力球是得分最多队员的主要发球方式;(3)绝大部分接应二传放下接发球任务,且大部分是本队的得分最多队员。本文对各种数据的分析希望能为以后得分最多的男排队员的选材、发球,扣球及拦网技术的训练、比赛过程中各种技术数据的统计分析以及排球运动员的管理提供参考。     

Coach ratings of skills and their relations to practice,play and successful transitions from youth-elite to adult-professional status in soccer

Elite soccer players (~15 yr) from professional academies in the UK were rated on technical, tactical, physical and creative skills by coaches at time 1 (T1). Players estimated accumulated hours in soccer practice (coach-led activities) and play (self-led activities) during childhood. Coach-ratings were again collected 2.5 yr later (T2) for players that received a professional contract (~17 yr). Adult-professional status was determined at T3 (~ 20 yr). Skill ratings distinguished across the three “future” groups (academy-only, youth-professional only and adult-professional), for all but creative skill. For players that transitioned to youth-professional, medium sized correlations were noted between childhood practice amounts and technical and creative skill ratings at T1, although practice amounts correlated more strongly with skill ratings at T2. Play amounts were not related to any skills. Within groups of youth elite athletes, domain-specific play in childhood, and to a lesser degree practice, were generally not good discriminators of specific-skills. The effects of sport-specific practice on the development (and discriminability) of skills takes time to emerge. We consider the implications for talent development models and purported links between play and creativity.     

Neuromuscular and technical abilities related to age in water-polo players

Testing is one of the important tasks in any multi-step sport programme. In most ball games, coaches assess motor, physical and technical skills on a regular basis in early stages of talent identification in order to further athletes’ development. The purpose of the study was to investigate anthropometric variables and vertical jump heights as a free throw effectiveness predictor in water-polo players of different age groups. Two hundred and thirty-six young (10–18 years) male water-polo players partitioned into three age groups underwent anthropometric variables’ measures and squat- and countermovement-jump tests, and performed water-polo free throws. Anthropometric variables, vertical jump heights and throw speed – as a proxy for free throw effectiveness – resulted different over age groups. Particularly, throw speed changed from 9.28 to 13.70 m · s^?1 (+48%) from younger to older players. A multiple-regression model indicated that body height, squat-jump height and throw time together explain 52% of variance of throw speed. In conclusion, tall height, high lower limb power and throwing quickness appeared to be relevant determinants for effective free throws. Such indications can help coaches during talent identification and development processes, even by means of novel training strategies. Further research is needed over different maturity statuses.     

对我国优秀女排运动员成才过程中年龄特征的研究

采用问卷调查与询访相结合的方法,对我国优秀女排运动员成才过程中年龄特征(包括专门训练、身体素质发展、技术掌握、竞技能力高峰期等的年龄特征)进行调查与分析。结果显示,该研究能为我国各层次排球队科学选材、科学训练等,提供运动员年龄方面的理论依据。     

伦敦奥运会中外优秀女排运动员若干非技术指标的对比分析

以参加2012年伦敦奥运会女子排球赛的全部队员的若干非技术指标为研究对象,采用文献资料法、数理统计法,对比分析法等研究方法,对144名参赛运动员的若干非技术性指标进行统计分析,以探索中国女排与国外优秀女排运动员在非技术指标上的差异。结果显示:中国女排与国外优秀女排运动员在年龄、扣球高度、拦网高度上有显著差异,在身高、体重、克托莱指数上,无差异。     

The relative age effect in the German Football TID Programme: Biases in motor performance diagnostics and effects on single motor abilities and skills in groups of selected players

Abstract

This study examined the disturbing effects of relative age on the talent identification process in the talent development programme of the German Football Association. The bias in the selection rate was examined via the extent of relative age effects. The bias in motor performance diagnostics was analysed by comparing the motor performance of selected players with normal motor development. The mechanisms underlying the relative age biases in motor performance were examined by modelling the direct and indirect effects of relative age on single motor performance tests for sprint, running agility, dribbling and ball passing and control. Data from 10,130 selected football players from the U12 to U15 age groups were collected in autumn 2010. The birth distribution differed significantly from the reference population with approximately 61% of the players born in the first half of the year. The selection probability was approximately two times higher for players born in the first quarter of the year than for players born in the last quarter. Revised motor performance diagnostics showed better results on average for relatively younger players. Path analysis revealed significant direct and indirect relative age effects for physiologically demanding tests and almost no effects for technically demanding tests. Large sample sizes allowed high resolution in relative age with additional informational content and multivariate modelling of the complex relationships among relative age, physical development and motor performance. The results are discussed on how relative age affects the effectiveness and fairness of talent identification and development processes.     

Getting to the top: an analysis of 25 years of career rankings trajectories for professional women’s tennis

Official rankings are the most common measure of success in professional women’s tennis. Despite their importance for earning potential and tournament seeding, little is known about ranking trajectories of female players and their influence on career success. Our objective was to conduct a comprehensive study of the career progression of elite female tennis talent. The study examined the ranking trajectories of the top 250 female professionals between 1990 and 2015. Using regression modelling of yearly peak rankings, we found a strong association between the shape of the ranking trajectory and the highest career ranking earned. Players with the highest career peak ranking were the youngest when first ranked. For example, top 10 players were first ranked at age 15.5 years (99% CI = 14.8–15.9), 1.2 years (99% CI = 0.8–1.5) earlier than top 51–100 players. Top 10 players were also ranked in the top 100 longer than other players, holding a top 100 ranking until a mean age of 29.0 years (99% CI = 27.8–30.3) compared with age 24.4 years (99% CI = 23.7–25.2) for top 51–100 players. Ranking trajectories were more distinct with respect to player age than years from first ranking. The present study’s findings will be instructive for players, coaches, and administrators in setting goals and assessing athlete development in women’s tennis.     

The effects of postseason break on stabilometric performance in female volleyball players

Ankle sprain is a common injury in volleyball. Poor stabilometric performance (SP) is associated with high risks of sustaining ankle sprain. Balance training can improve SP and reduce ankle sprain, but no research has studied the effects of detraining on SP in highly trained athletes. The purpose of this study was to determine the effects of one-month postseason break on SP in female volleyball players. Eleven NCAA female volleyball players participated in two eye-closed single-leg stance tests before and after a one-month postseason break. Stance time, center of pressure (COP) area, COP standard deviation, and COP mean velocity were assessed during the tests. During the postseason break, subjects conducted self-selected exercise and the average training duration was 87% lower compared to the competition season. Subjects demonstrated significant increases in anterioposterior (A/P) COP standard deviation (1.6 ± 0.4 vs. 1.8 ± 0.4 cm, p = 0.05), mediolateral (M/L) COP velocity (6.5 ± 1.5 vs. 7.1 ± 1.3 cm/s, p = 0.05), and overall COP velocity (10.1 ± 2.0 vs. 11.6 ± 1.9 cm/s, p = 0.02) after postseason break. SP decreased in highly trained female volleyball players after one-month postseason break. The decrease in SP indicated a possible increased risk for ankle sprain injury.     

我国与世界优秀排球运动员的年龄、体重、身高的对比研究

在现今世界排坛 ,队伍年龄结构是否合理 ,以及在体重、身高方面的差异 ,已经成为影响比赛结果的至关重要的因素。笔者将中国男女排运动员以及各省市甲级男女排运动员同国外优秀运动员的三项指标进行对比分析。结果显示 ,中国男排运动员在体重方面同世界优秀运动员存在较大差异 ,而年龄结构和身高指标较合理 ;各省市男排运动员三项指标同世界优秀运动员均存在显著性差异。中国女排在三项指标上都已经达到世界先进水平 ;各省市女排运动员的年龄、体重与世界优秀运动员存在显著差异。笔者认为 ,年龄结构不合理以及低体重下表现出的力量弱势 ,已经成为制约我国排球运动发展的重要原因。     

Relative age and birthplace effect in Japanese professional sports: a quantitative evaluation using a Bayesian hierarchical Poisson model

Relative age effect (RAE) in sports has been well documented. Recent studies investigate the effect of birthplace in addition to the RAE. The first objective of this study was to show the magnitude of the RAE in two major professional sports in Japan, baseball and soccer. Second, we examined the birthplace effect and compared its magnitude with that of the RAE. The effect sizes were estimated using a Bayesian hierarchical Poisson model with the number of players as dependent variable. The RAEs were 9.0% and 7.7% per month for soccer and baseball, respectively. These estimates imply that children born in the first month of a school year have about three times greater chance of becoming a professional player than those born in the last month of the year. Over half of the difference in likelihoods of becoming a professional player between birthplaces was accounted for by weather conditions, with the likelihood decreasing by 1% per snow day. An effect of population size was not detected in the data. By investigating different samples, we demonstrated that using quarterly data leads to underestimation and that the age range of sampled athletes should be set carefully.     

Prevalence of disordered eating in elite female athletes in team sports in Greece

ABSTRACT

The purpose of the study was to assess (a) the prevalence of disordered eating (DE) in elite female team sports players compared to non-athletes and (b) to compare DE prevalence in elite female players in basketball, volleyball and water polo. One hundred and seventy-five females were recruited (age 23.10?±?5.4, BMI 21.85?±?2.3?kg/m²), 53 were elite basketball players, 42 were elite volleyball players, 34 were elite water polo players and 46 were non-athletes. Participants completed the Eating Disorders Questionnaire (EDE-Q) and a physical activity questionnaire. The EDE-Q incorporates 36 statements which relate to the occurrence and frequency of key behaviours of eating disorders, under the following four subscales: Restraint, eating concern, shape concern and weight concern and a global score of disordered eating. No differences were found in the EDE-Q subscale score and global score between athletes and non-athletes. Only 6.2% of the total number of participants exhibited DE using the global score >2.3. Water polo players had significantly higher scores in the ‘eating concern’ subscale and in the frequency of key behavioural features of DE such as binge eating episodes and objective and subjective bulimic episodes, compared to volleyball and basketball players. In conclusion, team sport elite female players do not exhibit greater prevalence of DE compared to non-athletes. Water polo, a sport that emphasises leanness and control of body weight for international distinctions, is associated with a higher tendency to exhibit DE, when compared to other team sports.     

Effect of Dehydration on Passing Decision Making in Soccer Athletes

It seems that dehydration may impair decision-making performance in athletes. Purpose: This study aimed to investigate the influence of dehydration on passing decision-making performance in soccer players. Method: Participants were 40 male soccer players (M_age = 22.3 ± 2.3 years) who agreed to participate in the study and were randomly assigned to the following conditions: control (CON), dehydration (DEH), and euhydration (EUH). The players played in 2 games of 90 min in duration (2 45-min halves) followed by 2 15-min halves (overtime) with and without proper hydration. The Game Performance Assessment Instrument (GPAI) was considered for the analysis of passing decision making. Results: The GPAI analysis indicated effective reduction in the decision-making index in the DEH condition compared with the EUH and CON conditions, F(2, 38) = 31.4, p < .05, ES = 0.8. Conclusions: In conclusion, dehydration may be considered a mediating factor in the passing decision-making performance of male soccer athletes.     

我国男子排球后备力量调查及北京奥运战略分析

通过文献资料调研、调查访谈、体育测量和统计等方法对我国男子排球后备力量进行研究。结果显示,我国不缺乏男子青少年排球后备人才的生源,排球后备人才的梯队建设已初见端倪并正在不断地完善。建议以青少年运动员为主,挑选组建第29届奥运会集训队伍,进行针对性训练。     

广西普通高校排球高水平运动队的发展困境初探——以广西师范大学为例

中国女排在新中国成立70周年之际,用世界杯冠军为祖国献上最美好的生日贺礼。但是纵观中国三大球的发展,高校作为人才培养的重要机构,同样应该在国家体育事业发展中承担重要责任。本文通过文献资料法、问卷调查法、专家访谈法等,对广西师范大学排球高水平运动队的现状以及发展困境进行研究并找出其中问题,提出相应对策,这对广西高校排球运动的发展具有一定的参考价值并为高校排球运动发展助力。     

我国优秀女排运动员心脏形态与功能的研究

采用超声心动技术对我国优秀女排运动员安静状态、运动状态下心功能指标进行测量，并以体校业余女排运动员作为对照组，结果表明：优秀女排运动员具有左室腔扩大和心肌收缩能力强的特点。     

我国优秀女子排球运动员赛前有氧能力特征综合检测分析

研究表明:有氧能力是排球运动员能量供能的基础,是决定排球比赛胜负的关键所在。因此,对于排球运动员有氧能力的测试与评价对于指导运动员的训练、安排训练计划十分重要,为了全面了解我国优秀女子排球运动员赛前有氧能力状况,对即将参加2010—2011赛季全国排球联赛的64名优秀排球运动员赛前通过递增负荷运动过程中气体代谢指标、各阶段生理、生化指标的动态变化规律进行总结。结果显示:我国优秀女子排球运动员整体有氧能力与世界优秀运动员存在一定差距。随着排球运动水平、运动等级、运动成绩的不断提高,VO2max也相应表现为较高的水平。通过递增负荷运动中HR、BLA、Pmax、无氧阈功率、无氧乳酸阈的动态变化规律,显示我国优秀女子排球运动员在有氧、无氧代谢能力、心肺功能、速度耐力和耐乳酸能力存在位置特征,大致表现为副攻>二传>主攻>接应>自由人,提示我国女子排球运动员训练应根据场上不同位置有氧、无氧代谢能力特征的基本要求来制定合理的发展本专项所需要的生物能量能力的训练计划,从而提高训练的科学性和有效性。     

Effects of volleyball match-induced fatigue on knee joint position sense

Abstract

It has been suggested that a greater number of injuries during the last third of practice sessions or matches could be related to alteration of lower limb neuromuscular control due to neuromuscular fatigue. This fatigue-related effect can be mediated by changes in joint proprioception. In athletes, the use of functional fatigue protocols could have the advantage of mimicking the demands of sporting activity, thus reflecting more specifically the changes in neuromuscular control and proprioception observed in sport settings. The purpose of the present study was to assess the effect of fatigue induced by a volleyball match on knee joint position sense in elite volleyball players. Seventeen female volleyball players aged 18.9±4.2 years from the Portuguese national team volunteered for the study. Knee joint position sense was evaluated by an open kinetic chain technique and active knee positioning, and was reported using absolute, relative, and variable angular errors. Joint position sense measures were obtained before and immediately after a simulated volleyball match of five sets. To ensure that the match was sufficiently intense to induce fatigue, the perceived exertion or exercise intensity was assessed at the end of the match using Borg’ s rating of perceived exertion (RPE) scale. All participants completed the volleyball match (90min duration), reaching or exceeding 15 on the RPE scale (15.59±0.71; range 15–17), equivalent to “hard/heavy work”. After the volleyball match, a significant increase in absolute (2.11°) and relative (1.71°) angular errors was detected. Match-induced fatigue significantly exacerbated the overestimation of the test position. Moreover, the reliability and accuracy in estimating knee angles decreased from rest to the fatigued state, as shown by the increase (264%) in variable error. Our results show that fatigue induced by a volleyball match has a marked effect on knee joint position sense in elite female volleyball players. Knee joint position sense was less accurate and less consistent after the volleyball match. Fatigue induced by a simulated competitive volleyball match resulted in proprioceptive deficits, decreasing sensorimotor system acuity in female volleyball players.