Development of 1500m Pacing Behavior in Junior Speed Skaters: A Longitudinal Study.

Providing insight in the development of pacing behavior in junior speed skaters and analyse possible differences between elite, sub-elite, and non-elite juniors.1500m season best times (SBT) and corresponding pacing behavior were obtained longitudinally for 104 Dutch male speed skaters at age 13-14(U15), 15-16(U17), and 17-18(U19) years. Based on their U19 SBT, skaters were divided into elite(n=17), sub-elite(n=64), and non-elite(n=23) groups. Pacing behavior was analysed using the 0-300m, 300-700m, 700-1100m and 1100-1500m times, expressed as a percentage of final time. Mixed analyses of variance were used for statistical analyses.With age, pacing behavior generally developed towards a slower 0-300m and 1100-1500m and a faster mid-section relative to final time. While being faster on all sections, the elite were relatively slower on 0-300m (22.1±0.27%) than the sub-elite and non-elite (21.5±0.44%)(p<0.01), but relatively faster on 300-700m (24.6±0.30%) than the non-elite (24.9±0.58%)(p=0.002). On 700-1100m, the elite and sub-elite (26.2±0.25%) were relatively faster than the non-elite (26.5±0.41%)(p=0.008). Differences in the development of pacing behavior were found from U17-U19 with relative 700-1100m times decreasing for the elite and sub-elite (26.2±0.31% to 26.1±0.27%), but increasing for the non-elite (26.3±0.29% to 26.5±0.41%)(p=0.014).Maintaining high speed into 700-1100m, accompanied by a relatively slower start, appears crucial for high performance on the 1500m speed skating. Generally, juniors develop towards this profile, with a more pronounced development towards a relative faster 700-1100m from U17-U19 for elite junior speed skaters. The results of the present study indicate the relevance of pacing behavior for talent development

Measuring Agility in Tennis, Badminton, and Squash:A Systematic Review

A systematic review in PubMed, Web of Science, SPORTDiscus, PsycINFO, and Google Scholar was conducted to provide a state-of-the-science overview of agility tests in the racquet sports tennis, badminton, and squash while evaluating their measurement properties. Twenty articles were included covering 28 agility tests. Results showed 10 sport-specific agility tests of which 5 were assessed on reliability and 6 on validity. Both the Badcamp and the badminton-specific speed ("agility") test were identified as suitable agility tests available for badminton. For tennis and squash, there were no sport-specific agility tests identified in the literature showing both reliable and valid results. Future research should focus on developing sport-specific agility tests for tennis and squash, including assessment of the reliability and validity of the tests.</p

The tactics of successful attacks in professional association football:large-scale spatiotemporal analysis of dynamic subgroups using position tracking data

Association football teams can be considered complex dynamical systems of individuals grouped in subgroups (defenders, midfielders and attackers), coordinating their behaviour to achieve a shared goal. As research often focusses on collective behaviour, or on static subgroups, the current study aims to analyse spatiotemporal behaviour of dynamic subgroups in relation to successful attacks. We collected position tracking data of 118 Dutch Eredivisie matches, containing 12424 attacks. Attacks were classified as successful (N = 1237) or non-successful (N = 11187) based on the potential of creating a scoring opportunity. Using unsupervised machine learning, we automatically identified dynamic formations based on position tracking data, and identified dynamic subgroups for every timeframe in a match. We then compared the subgroup centroids to assess the intra- and inter-team spatiotemporal synchronisation during successful and non-successful attacks, using circular statistics. Our results indicated subgroup-level variables provided more information, and were more sensitive to disruption, in comparison to team-level variables. When comparing successful and non-successful attacks, we found decreases (p < .01) in longitudinal inter- and intra-team synchrony of interactions involving the defenders of the attacking team during successful attacks. This study provides the first large-scale dynamic subgroup analysis and reveals additional insights to team-level analyses

Design of a Tennis-Specific Agility Test (TAT) for Monitoring Tennis Players

Agility is an important ability for tennis players. To be successful in the rallies, players must perform rapid, multidirectional movements in response to the ball and/or the position of the opponent. For a test to be representative in monitoring agility performance, it should capture a combination of the physical and cognitive agility performance. Considering that literature reports no reliable and valid sport-specific agility test for tennis, the aim of this article was to design and evaluate the measurement properties of a Tennis-specific Agility Test (TAT). To evaluate the TAT, test-retest reliability, concurrent validity, and feasibility were assessed. For reproducibility, a two-way mixed ANOVA was performed. Concurrent validity was assessed using Pearson correlations. A total of 69 tennis players participated in this study of whom 16 competed at the international (22 ± 3.7 years, playing level (Dynamic Rating System): .8 ± .3), 43 at the national (14 ± 1.4 years, playing level: 4.6 ± 1.4), and 10 at the regional level (15 ± 0.8 years, playing level: 4.9 ± 1.1). Test-retest reliability was found to be moderate with an Intra-Class Correlation coefficient (ICC) of .74 (p < .01) and a percentual minimal detectable change (%MDC) of 6.2%. Concurrent validity was found to be moderate by comparison with a recognised agility test, the Spider Drill, which measures only the physical component (.70; p < .01), and by comparison with tennis performance for both boys (r = .67; p < .01) and girls (r = .72; p < .01). The feasibility was high with short time for preparation (five to ten minutes) and time per participant (<5 minutes). In conclusion, the TAT shows promising results for assessing sport-specific agility performance in tennis making it likely to be used in the practical setting

Primary School Pupils:Unequal GMC Developmental Pathways in a Single School Year

Gross motor coordination (GMC) is essential for the development of specific motor skills and long-term participation in physical activities and sports. Group analysis reveals that, on average, children develop these skills gradually; however, how individuals develop GMC is less clear. The main aim of this study is to increase the understanding of developmental patterns within one school year, and whether children’s grade, gender, or baseline GMC proficiency are associated with these developmental patterns. In total, 2594 Dutch children aged 6–12 years performed the modified Körper Koordinations Test für Kinder (KTK3+) twice in one school year (autumn and spring). The KTK3+ includes four subtests: walking backwards, moving sideways, jumping sideways, and eye-hand coordination (EHC) test. On average, children developed significantly on all subtests (p < 0.001). At baseline, children in higher grades scored significantly higher than children in lower grades, and children in grades 5 and 6 (age 9 and 10 years) showed most development (raw scores on average, p < 0.001). Boys outperformed girls on EHC across all grades, whereas girls outperformed boys on walking backwards. Nevertheless, both boys and girls developed similarly. Children with lower scores at baseline developed more quickly across all grades. Noteworthy is that 12.1–24% (depending on the test item) of the children scored lower in the spring than in the autumn tests. On average, children develop their GMC; however, we report large differences in their individual trajectories and note that a substantial number did not show a positive GMC development. Further research should examine GMC development with more possible influencing factors as well as over a longer time span to better understand differences in children’s GMC development. This may result in more individualized programs in PE lessons, enabling children to optimally develop their GMC, and better use of GMC assessment tools to monitor children’s development

Creating a place for learning - Bridging physical and virtual learning spaces at conferences

This paper presents a reflective case study of the introduction of Learning Toolbox as an ePoster solution for conferences. The Learning Toolbox ePoster platform is designed to overcome practical knowledge sharing and communication problems encountered in both the traditional paper poster and standard, screen-based ePoster approaches. Additionally it draws on the trialogic learning theory, by offering ePoster authors and viewers support for discussion and knowledge development focused on an object (the ePoster). As such it aims to support greater engagement, community building and knowledge creation within and beyond an academic conference. In this paper we describe the educational aims behind Learning Toolbox, the technological solution, the practical approach used to introduce it as the ePoster platform at a large international conference, a review of its use at the conference and then reflect on what contributed to its successful adoption. Finally open challenges and further work are identified (including evaluating the impact on learning and engagement beyond the conference and scaling up the numbers of ePosters whilst still allowing authors to present to and discuss their work directly with an audience) to which we propose possible solutions

Biliary Bicarbonate Secretion Constitutes a Protective Mechanism against Bile Acid-Induced Injury in Man

Background: Cholangiocytes expose a striking resistance against bile acids: while other cell types, such as hepatocytes, are susceptible to bile acid-induced toxicity and apoptosis already at micromolar concentrations, cholangiocytes are continuously exposed to millimolar concentrations as present in bile. We present a hypothesis suggesting that biliary secretion of HCO(3)(-) in man serves to protect cholangiocytes against bile acid-induced damage by fostering the deprotonation of apolar bile acids to more polar bile salts. Here, we tested if bile acid-induced toxicity is pH-dependent and if anion exchanger 2 (AE2) protects against bile acid-induced damage. Methods: A human cholangiocyte cell line was exposed to chenodeoxycholate (CDC), or its glycine conjugate, from 0.5 mM to 2.0 mM at pH 7.4, 7.1, 6.7 or 6.4, or after knockdown of AE2. Cell viability and apoptosis were determined by WST and caspase-3/-7 assays, respectively. Results: Glycochenodeoxycholate (GCDC) uptake in cholangiocytes is pH-dependent. Furthermore, CDC and GCDC (pK(a) 4-5) induce cholangiocyte toxicity in a pH-dependent manner: 0.5 mM CDC and 1 mM GCDC at pH 7.4 had no effect on cell viability, but at pH 6.4 decreased viability by >80% and increased caspase activity almost 10- and 30-fold, respectively. Acidification alone had no effect. AE2 knockdown led to 3- and 2-fold enhanced apoptosis induced by 0.75 mM CDC or 2 mM GCDC at pH 7.4. Discussion: These data support our hypothesis of a biliary HCO(3)(-) umbrella serving to protect human cholangiocytes against bile acid-induced injury. AE2 is a key contributor to this protective mechanism. The development and progression of cholangiopathies, such as primary biliary cirrhosis, may be a consequence of genetic and acquired functional defects of genes involved in maintaining the biliary HCO(3)(-) umbrella. Copyright (C) 2011 S. Karger AG, Base

Novel immortalized human fetal liver cell line, cBAL111, has the potential to differentiate into functional hepatocytes

BACKGROUND: A clonal cell line that combines both stable hepatic function and proliferation capacity is desirable for in vitro applications that depend on hepatic function, such as pharmacological or toxicological assays and bioartificial liver systems. Here we describe the generation and characterization of a clonal human cell line for in vitro hepatocyte applications. RESULTS: Cell clones derived from human fetal liver cells were immortalized by over-expression of telomerase reverse transcriptase. The resulting cell line, cBAL111, displayed hepatic functionality similar to the parental cells prior to immortalization, and did not grow in soft agar. Cell line cBAL111 produced urea, albumin, cytokeratin 18 and 19 and showed high glutathione S transferase pi mRNA levels. In contrast to hepatic cell lines NKNT-3 and HepG2, all hepatic functions were expressed in cBAL111, although there was considerable variation in their levels compared with primary mature hepatocytes. When transplanted in the spleen of immunodeficient mice, cBAL111 engrafted into the liver and partly differentiated into hepatocytes showing expression of human albumin and carbamoylphosphate synthetase without signs of cell fusion. CONCLUSION: This novel liver cell line has the potential to differentiate into mature hepatocytes to be used for in vitro hepatocyte applications

Система высшего образования Тайваня глазами иностранных студентов на современном этапе

Объект:система высшего образования Тайваня.Предмет:отношение иностранных студентов к высшему образованию Тайваня. В процессе исследования проводились сбор теоретической информации о системе Высшего образования Тайваня,интервью и опрос среди студентов,обучавшихся на Тайване,анализ полученных данных. Область применения:положения и выводы,содержащиеся в работе,могут быть использованы для дальнейшей разработки вопроса глобализации образования,при создании моделей образовательной интеграции,при проведении исследований,касающихся образования Тайваня,при ведении статистистической сводкиObject:system of higher education in Taiwan.Subject:attitude of foreign students towards the higher education in Taiwan. In the course of this research paper was gathered theoretical information about the higher education system in Taiwan,were conducted polls and interviews among the students who were studying in Taiwan,the obtained data was analyzed. The basic thesis and conclusions of this paper can be applied in further research of the problem of globalization in education, in development of models of educational integration,in research concerning the educational system of Taiwan,in data collation,results of this research can be used in designing educational programs for foreign students

Assessing Cognitive Performance in Badminton Players:A Reproducibility and Validity Study

Fast reaction and good inhibitory control are associated with elite sports performance. To evaluate the reproducibility and validity of a newly developed Badminton Reaction Inhibition Test (BRIT), fifteen elite (25 +/- 4 years) and nine non-elite (24 +/- 4 years) Dutch male badminton players participated in the study. The BRIT measured four components: domain-general reaction time, badminton-specific reaction time, domain-general inhibitory control and badminton-specific inhibitory control. Five participants were retested within three weeks on the badminton-specific components. Reproducibility was acceptable for badminton-specific reaction time (ICC = 0.626, CV = 6%) and for badminton-specific inhibitory control (ICC = 0.317, CV = 13%). Good construct validity was shown for badminton-specific reaction time discriminating between elite and non-elite players (F = 6.650, p 0.05). Concurrent validity for domain-general reaction time was good, as it was associated with a national ranking for elite (. = 0.70, p 0.05). In conclusion, reproducibility and validity of inhibitory control assessment was not confirmed, however, the BRIT appears a reproducible and valid measure of reaction time in badminton players. Reaction time measured with the BRIT may provide input for training programs aiming to improve badminton players' performance