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Validity of simple field tests as indicators of match-related physical performance in top-level professional soccer players
No full textThe aim of this study was to examine the construct validity of selected field tests as indicators of match-related physical performance. During the competitive season, eighteen professional soccer players (age 26.2 ± 4.5 yrs, mass 80.8 ± 7.8 kg, and height 181.9 ± 3.7 cm) completed an incremental running field test to exhaustion, a vertical-jump and a repeated-sprint ability (RSA) test. Match physical performance was quantified during official matches using a video-computerized, semi-automatic, match analysis image recognition system, (ProZone®, Leeds, UK). The selected measures of match physical performance were: total distance covered (TD), high intensity running (HIR: > 14.4 km · h-1), very high intensity running (VHIR:> 19.8 km · h-1), sprinting (> 25.2 km · h-1) and top running speed. Significant correlations were found between peak speed reached during the incremental field test and TD (r = 0.58, R2 = 0.34; p < 0.05), HIR (r = 0.65, R2 = 0.42; p < 0.01) and VHIR (r = 0.64, R2 = 0.41; p < 0.01). Significant correlations were also found between RSA mean time and VHIR (r = - 0.60, R2 = 0.36; p < 0.01) and sprinting distance (r = - 0.65, R2 = 0.42; p < 0.01). Significant differences were found between the best and worst group as defined by the median split technique for peak speed (TD = 12 011 ± 747 m vs. 10 712 ± 669, HIR = 3192 ± 482 m vs. 2314 ± 347 m, and VHIR = 1014 ± 120 vs. 779 ± 122 m, respectively; p < 0.05) and RSA mean time (VHIR = 974 ± 162 m vs. 819 ± 144 m, and sprinting = 235 ± 56 vs. 164 ± 58 m, respectively; p < 0.05). In conclusion, this study gives empirical support to the construct validity of RSA and incremental running tests as measures of match-related physical performance in top-level professional soccer players
Validity of simple field tests as indicators of match-related physical performance in top-level professional soccer players
No full textEffect of match-related fatigue on short-passing ability in young soccer players.
No full textPURPOSE: To examine whether the fatigue accumulated during match play or determined by short bouts of high-intensity intermittent activities affect short-passing ability in junior soccer players. A further aim was to examine the influence of physical fitness as measured using the Yo-Yo Intermittent Recovery Test (YYIRT) on the changes in short-passing ability after a 5-min simulation of high-intensity activities (HIS). METHODS: Sixteen players (mean +/- SD: age 17.6 +/- 0.5 yr, height 174 +/- 7 cm, body mass 68 +/- 6 kg) participated in the study. A quasi-experimental control-period design was used for the study. Short-passing ability was measured using the Loughborough Soccer Passing Test (LSPT). Players completed the LSPT in two sessions during the 1-wk control period, followed by two unofficial matches during which the LSPT was performed during and after the first and the second halves of the game. Furthermore, the change in LSPT performance was determined after 5 min of HIS. RESULTS: A decline in LSPT performance was found during and after the game (P < 0.01). The accuracy of the LSPT decreased after the HIS. A significant correlation was found between the YYIRT scores and the decline in LSPT performance (accuracy, total time, total time with penalties) after HIS (r = -0.51 to -0.65; P < 0.05). CONCLUSIONS: This study showed that the fatigue developed during a match and after relatively short bouts of high-intensity intermittent activities has a detrimental effect on short-passing ability, and that the fatigue-related decline in technical proficiency for a given intensity is associated with the fitness level of the players
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
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