1,720,961 research outputs found
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
EFFECTS OF DIFFERENT RELATIVE LOADS ON POWER PERFORMANCE DURING THE BALLISTIC PUSH-UP
No full textThe purpose of this investigation was to examine the effect of load on force and power performance during a ballistic push-up. Sixty (24.5 +/- 4.3 years, 1.75 +/- 0.07 m, and 80.8 +/- 13.5 kg) recreationally active men who participated in this investigation completed all testing and were included in the data analysis. All participants were required to perform a 1 repetition maximum bench press, and ballistic push-ups without external load (T1), with 10% (T2) and 20% (T3) of their body mass. Ballistic push-ups during T2 and T3 were performed using a weight loaded vest. Peak and mean force, power, as well as net impulse and flight time were determined for each ballistic push-up. Peak and mean force were both significantly greater (p > 0.01) during T3 (1,062 +/- 202 and 901 +/- 154 N, respectively), than both T2 (1,017 +/- 202 and 842 +/- 151 N, respectively) and T1 (960 +/- 188 and 792 +/- 140 N, respectively). Peak and mean power were significantly greater (p < 0.01) during T1 (950 +/- 257 and 521 +/- 148 W, respectively), than both T2 (872 +/- 246 and 485 +/- 143 W, respectively) and T3 (814 +/- 275 and 485 +/- 162 W, respectively). Peak and mean power were greatest during T1, regardless of participants' strength levels. Significant (p > 0.01) greater net impulse and smaller peak velocity and flight time were also noted from T1 to T3. Results of this investigation indicated that maximal power outputs were achieved without the use of an external load when performing the ballistic push-up, regardless of the participants' level of strength
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
CAN THE AIR FORCE PHYSICAL FITNESS ASSESSMENT PREDICT AEROBIC AND ANAEROBIC CAPACITY?
No full textCameron S. Mackey1, Tyler W.D. Muddle1, & Jason M. DeFreitas1
1 Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, OK
PURPOSE: To determine if the components of the Air Force physical fitness assessment (PFA) can predict laboratory/clinical based performance capabilities. METHODS: 30 male Air Force Reserve Officers’ Training Corps (ROTC) cadets (mean ± SD age = 20.3 ± 2.1 yr) participated in this investigation. Each performed an incremental treadmill test to exhaustion to determine peak oxygen uptake (VO2peak; ml/kg/min) and a 30-sec. Wingate Anaerobic Test (WAnT). A commercially-designed bioelectrical impedance spectroscopy (BIS) device was utilized to determine body fat percentage (BF%). The 1.5 mile run times, 1-minute pushups, 1-minute sit-ups, and waist circumference were collected during participants’ ROTC PFA. Relationships among the dependent variables were analyzed with Pearson correlation coefficients. Stepwise, multiple regression was used to determine the relative contributions of the PFA components to the VO2peak and WAnT measurements. RESULTS: The means ± SDs for each variable, as well as the results of the correlations are shown in Table 1. The multiple regression analysis indicated that 1.5 mile run time and waist circumference contributed significantly to the prediction of VO2peak (p = 0.002 and p = 0.036, respectively). The 1.5 mile run time contributed significantly to the prediction of the WAnT anaerobic capacity (p = 0.005), and waist measurement contributed significantly to the prediction of BF% (p = 0.022). CONCLUSION: There were significant relationships among run time, VO2peak, WAnT fatigue index and anaerobic capacity. In addition, the PFA composite score had a significant relationship to WAnT anaerobic capacity, and the waist circumference was significantly related to BF%. However, these data suggest that while the pushup and sit-up components of the PFA may not be able to predict aerobic and anaerobic capacities, the 1.5 mile run time and waist circumference showed significant contributions to VO2peak, WAnT anaerobic capacity, and BF%
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