1,720,968 research outputs found
Long-term changes of body composition in an elite soccer player and its association with cognition: a ten-year retrospective study
No full textBACKGROUND: In soccer, understanding of long-term body composition changes associated with training and competition would be useful for both players and coaches. However, studies of this kind are hampered by frequent interclub transfer, changes in club policy or continued availability of the relevant facilities.METHODS: In this work we tracked lean and fat mass of an elite soccer player along ten consecutive years by means of dual-energy X-ray absorptiometry, which was carried out at preseason, mid-season, and end-season. Cognitive performance was also evaluated.RESULTS: Correlation analysis showed that whole-body and regional fat mass increases with age (P=0.009 or less). Repeated measure ANOVA showed that whole-body lean soft tissue mass tended to cycle along the competitive season (P=0.059) with an increase at mid-season and, to a lesser extent, end-season vs. preseason. Fat mass and lean soft tissue mass respectively increased (P=0.018) and tended to decrease (P=0.083) during off-season. Several seasonal changes in body composition were statistically meaningful (i.e., >least significant change). Average reaction time in visual attention task test increased with fat mass (r=0.866, P=0.001).CONCLUSIONS: These novel results highlight body composition trajectories and their relationship with cognition in an elite soccer player
Body composition in Karate: a dual-energy X-ray absorptiometry study
Full text linkKarate is a widely practiced combat sport. Karatekas' body composition has typically been obtained in small groups using skinfolds or bioelectric impedance. In this work, we assessed three-compartment body composition using the accurate dual-energy X-ray absorptiometry technique (QDR Horizon, Hologic) in a large sample (n = 58; 74% males) of black belt karatekas. Stature-adjusted body composition indices (fat mass index; fat-free mass index; bone mineral apparent density) were calculated. The Student's t-test was used for group-group analysis. Correlation was assessed using the Pearson's r. The ability of fat-free soft tissue mass to predict bone mineral content and areal bone mineral density was assessed with linear regression. Reference mean and quartile values for whole-body and regional body composition were obtained for the male athletes. The body composition indices were generally more favorable in the male than female karatekas. The bone mineral apparent density was similar in the males and females at all sites except the right leg. The fat-free soft tissue mass predicted the bone mineral content and areal bone mineral density with good accuracy (R-2 = 0.542-0.827; p < 0.001 for all models). The data presented in this paper are expected to be of use for karate coaches, physical trainers, and participants interested in assessing and monitoring athletes' body composition
Effect of distinct impact loading sports on body composition in pre-menarcheal girls.
No full textIntroduction. - The aim of this preliminary work was to explore the effect of distinct impact loading sport and different amount (h/w) of impact activity on body composition of pre-menarcheal girls.Subjects and methods. - This study included 30 pre-menarcheal girls (aged 8.0-12.9 years) training for at least 1 year in volleyball (VOLLEY, n=10) or artistic gymnastics at high (HGYM, n=10) and low (LGYM, n=10) amount (h/w) of training. Body composition (bone mineral content [BMC], fat-free soft tissue mass [FFST], fat mass [FM], and %FM) was assessed by dual-energy X-ray absorptiometry (DXA) at the total body (TB) and regional (arms, legs, trunk) level as well as specific axial skeleton sites (thoracic and lumbar spine, pelvis).Results. - After adjusting for body mass and stature, TB composition measurements were all significantly (P<0.01) different in the three groups of pre-menarcheal athletes. VOLLEY had lower BMC and FFST, and greater FM and %FM vs. both HGYM and LGYM. The main difference between LGYM and HGYM was greater %FM in the former. Similar results were found at the regional level (but for similar BMC in the legs) and at lumbar spine and pelvis.Conclusion. - This study suggests that in pre-menarcheal girls training in impact loading activity, difference in sport type mainly affect %FM, and the amount of impact activity (h/w) has major impact on BMC accrual. (C) 2013 Elsevier Masson SAS. All rights reserved
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
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
Erratum: Correction: Predictors of Ball Velocity in the Sitting Volleyball Serve: A Causal Analysis (International journal of sports medicine (2023) 44 8 (576-583))
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