1,720,958 research outputs found
Evaluating the upper-body strength and power from a single test: the ballistic puh-up.
No full textAbstract: Wang, R, Hoffman, JR, Sadres, E, Bartolomei, S, Muddle, TWD, Fukuda, DH, and Stout, JR. Evaluating upper-body strength and power from a single test: the ballistic push-up. J Strength Cond Res 31(5): 1338–1345, 2017—The purpose of this study was to examine the reliability of the ballistic push-up (BPU) exercise and to develop a prediction model for both maximal strength (1 repetition maximum [1RM]) in the bench press exercise and upper-body power. Sixty recreationally active men completed a 1RM bench press and 2 BPU assessments in 3 separate testing sessions. Peak and mean force, peak and mean rate of force development, net impulse, peak velocity, flight time, and peak and mean power were determined. Intraclass correlation coefficients were used to examine the reliability of the BPU. Stepwise linear regression was used to develop 1RM bench press and power prediction equations. Intraclass correlation coefficient's ranged from 0.849 to 0.971 for the BPU measurements. Multiple regression analysis provided the following 1RM bench press prediction equation: 1RM = 0.31 × Mean Force − 1.64 × Body Mass + 0.70 (R2 = 0.837, standard error of the estimate [SEE] = 11 kg); time-based power prediction equation: Peak Power = 11.0 × Body Mass + 2012.3 × Flight Time − 338.0 (R2 = 0.658, SEE = 150 W), Mean Power = 6.7 × Body Mass + 1004.4 × Flight Time − 224.6 (R2 = 0.664, SEE = 82 W); and velocity-based power prediction equation: Peak Power = 8.1 × Body Mass + 818.6 × Peak Velocity − 762.0 (R2 = 0.797, SEE = 115 W); Mean Power = 5.2 × Body Mass + 435.9 × Peak Velocity − 467.7 (R2 = 0.838, SEE = 57 W). The BPU is a reliable test for both upper-body strength and power. Results indicate that the mean force generated from the BPU can be used to predict 1RM bench press, whereas peak velocity and flight time measured during the BPU can be used to predict upper-body power. These findings support the potential use of the BPU as a valid method to evaluate upper-body strength and power
Response-Methodological issues associated with the use of force plates when assessing push-ups power.
No full textWe read with interest the article by Wang et al. (5). The authors calculated the peak power and mean power of ballistic push-ups as the highest and average power output using similar methods as for lower-body jump squats assessment (i.e., force-plate technique). We believe that the evaluation of power in Wang et al.'s (5) study is based on a misinterpretation of the articles cited in their study. Specifically, Hogarth et al.'s (4) study performed measures which indicate the performance of the exercises but did not actually evaluate power. However, Cormie et al.'s (1) study compared different methods of estimating peak power output. There are sufficient and necessary conditions that have to be respected in order to be able to correctly estimate the power on lower-limb dynamic exercises. We believe that Wang et al. (5) have in appropriately applied this method to the upper-limbs, for the following reasons:
Cormie et al. (1) demonstrated that the force-plate technique underestimates the velocity and power output. In addition, this approach assumes linear kinetics, whereas the push-up movement involves rotation of the body about the toes. Moreover, in the push-ups, contrary to the vertical jump where the hands are “free,” both the hands and feet are in contact with the ground so all ground reaction forces should be measured. Nevertheless, only one part of the external forces were measured (hand-related forces) in the experimental protocol in the study of Wang et al. (5). The power provided in lower-limb vertical jump articles (1,3) is linear as the body moves upward in a linear motion. However, the trajectory of the center of mass of the body in the longitudinal plane when performing jump/ballistic push-ups is a circular arc around the toes (fixed point). A kinematic analysis is therefore needed to verify the path of the push-up and quantify the errors in power estimated when it is assumed that the push-up jump movement is perfectly vertical.
We believe that this “transposed” technique used with the lower-limb to the upper-limbs is inappropriate. This takes on assumptions and can cause large measurement errors. We therefore suggest either (a) using some indices that are related to components of power without actual measurement of power (2), such as rate of force development, impulse, and flight-time, or (b) using 2 synchronized force-plates, which allow supporting the whole body in push-up position. We hope our concern be taken as constructive
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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