1,720,994 research outputs found
New genetic model for predicting phenotype traits in sports
No full textThe aim of the current study was to construct a genetic model with a new algorithm for predicting athletic-performance variability based on genetic variations. Methods: The influence of 6 polymorphisms (ACE, ACTN-3, BDKRB2, VDR-ApaI, VDR-BsmI, and VDR-FokI) on vertical jump was studied in top-level male Italian soccer players (n = 90). First, the authors calculated the traditional total genotype score and then determined the total weighting genotype score (TWGS), which accounts for the proportion of significant phenotypic variance predicted by the polymorphisms. Genomic DNA was extracted from saliva samples using a standard protocol. Genotyping was performed using polymerase chain reaction (PCR). Results: The results obtained from the new genetic model (TWGS) showed that only 3 polymorphisms entered the regression equation (ACTN-3, ACE, and BDKRB2), and these polymorphisms explained 17.68-24.24% of the verticaljump variance. With the weighting given to each polymorphism, it may be possible to identify a polygenic profile that more accurately explains, at least in part, the individual variance of athletic-performance traits. Conclusions: This model may be used to create individualized training programs based on a player's genetic predispositions, as well as to identify athletes who need an adapted training routine to account for individual susceptibility to injury
Characterization of static balance abilities in elite football (soccer) players by playing position and age
No full textIn this study, we investigated the static balance of adult and adolescent elite soccer players to understand how expertise and playing position influence postural control. Seventy-one national level players were tested using a force platform to acquire Center-of-Pressure (COP) data in uni- and bipedal stance and calculate sway area (SA), COP path length, velocity and displacements. The results show significant differences in postural sway related to age and playing position only for single-limb stance. In particular, midfielders exhibited significantly lower values of SA with respect to defenders (–48%, p = 0.001) and the under-15 players exhibited SA 42–64% higher than all the others (p = 0.001). In the light of planning training or rehabilitation programs specific for each player’s role and age, sway measurements may supply useful, objective and reliable information only for the unipedal test as the bipedal standing appears not challenging enough to let differences in balance abilities emerge
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
INFLUENCE OF EXPERTISE AND PLAYING POSITION ON POSTURAL CONTROL OF YOUNG AND ADULT ELITE SOCCER PLAYERS
No full textIntroduction In soccer, balance represents a key factor to achieve an optimal performance level and reduce the risk of lower limb injuries.
In particular, it has been demonstrated that soccer players exhibit, due to the specific training, superior postural control in unipedal
stance conditions with respect to either untrained subjects or athletes of other disciplines (Matsuda et al, 2008, 2010). Nevertheless, the
effects of playing position and expertise have been scarcely investigated (Bizid and Paillard, 2006, Paillard et al., 2006). Therefore, the
aim of this study was to assess the possible changes in postural control performances in young and adult elite soccer players according
OP-BN06 Biomechanics [BM] 6
598 18TH ANNUAL CONGRESS OF THE EUROPEAN COLLEGE OF SPORT SCIENCE
to their age (and thus expertise) and playing position. Methods A total of 83 adult and young athletes who compete in national tournaments,
were recruited for the study. In particular we tested players of Italian first league (Serie A, n=23) and youth leagues (Under 19,
n=19, Under 17, n=26, Under 15, n=15). Using a pressure platform, time series of center of pressure (COP) position were acquired under
bipedal (BP) and unipedal (UP) conditions. Data processing allowed to calculate Sway Area (SA), COP Path Length, COP displacements in
Antero-Posterior (AP) and Medio-Lateral (ML) directions, as well as COP velocity. Results Under BP conditions, no statistically significant
differences were observed between the teams or different playing positions. For the single leg stance, no effect of limb was detected,
while playing position influenced all the considered variables except COP velocity in ML direction, and team was responsible for changes
in SA only. In particular, post-hoc analysis revealed that midfielders achieved the best performances and defenders the poorest. Also,
youngest players of Under 15 team were characterized by SA values significantly higher than both Under 19 and Serie A team. Discussion
An interesting result of this study is represented by the superior balance performance exhibited by the midfielders, probably due to their
habit to handle the ball for longer times during a match. It is also noticeable that the effect of age on postural control is evident only in UP
stance, being the youngest athletes characterized by the worst postural control. Our data also suggest that BP tests might not be sensitive
enough to investigate balance in soccer players. Consistently with previous studies, no differences in postural sway were found between
dominant and non-dominant limb. References Matsuda S, Demura S, Uchiyama M. (2008) J Sports Sci.26(7), 775-779 Matsuda S, Demura
S, Demura T. (2010) Percept Mot Skills 110(3), 751-760 Bizid R, Paillard, T. (2006) Science & Sports 21(1), 23-25 Paillard T et al. J Athl Train
(2006) 41(2), 172-17
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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