1,720,955 research outputs found
Menstrual and oral contraceptive cycle phases do not affect submaximal and maximal exercise responses
No full textTo examine whether the menstrual or monophasic oral contraceptive cycle phases affect submaximal (oxygen uptake (
̇
V
O2 ) kinetics, maximal lactate steady-state (MLSS)) and maximal (
̇
V
O2max , time-to-exhaustion (TTE)) responses to exercise in healthy, active women. During the mid-follicular or inactive-pill phase and the mid-luteal or active-pill phase of the respective menstrual or oral contraceptive cycle, 15 non-oral contraceptive users (mean and standard deviation (SD) (±): 27 ± 6 years; 171 ± 5 cm; 65 ± 7 kg) and 15 monophasic oral contraceptive users (24 ± 4 years; 169 ± 10 cm; 68 ± 10 kg) performed: one
̇
V
O2 kinetics test; one ramp-incremental test; two to three 30-minute constant-load cycling trials to determine the power output corresponding to MLSS (MLSSp ), followed by a TTE trial. The phase of the menstrual or oral contraceptive cycle did not affect the time constant of the
̇
V
O2 kinetics response (τ
̇
V
O2 ) (mid-follicular, 20 ± 5 seconds and mid-luteal, 18 ± 3 seconds; inactive-pill, 22 ± 8 seconds and active-pill, 23 ± 6 seconds),
̇
V
O2max (mid-follicular, 3.06 ± 0.32 L min-1 and mid-luteal, 3.00 ± 0.33 L min-1 ; inactive-pill, 2.87 ± 0.39 L min-1 and active-pill, 2.87 ± 0.45 L min-1 ), MLSSp (mid-follicular, 181 ± 30 W and mid-luteal, 182 ± 29 W; inactive-pill, 155 ± 26 W and active-pill, 155 ± 27 W), and TTE (mid-follicular, 147 ± 42 seconds and mid-luteal, 128 ± 54 seconds; inactive-pill, 146 ± 70 seconds and active-pill, 139 ± 77 seconds) (P > .05). The rate of perceived exertion (RPE) at minute 30 of the MLSSp trials was greater in the mid-follicular phase (6.2 ± 1.5) compared with the mid-luteal phase (5.3 ± 1.4) for non-oral contraceptive users (P = .022). The hormonal fluctuations between the menstrual and oral contraceptive cycle phases had no detectable effects on submaximal and maximal exercise performance, even when RPE differed
Evaluating the accuracy of using fixed ranges of METs to categorize exertional intensity in a heterogeneous group of healthy individuals: Implications for cardiorespiratory fitness and health outcomes
No full textBackground
Appropriate quantification of exertional intensity remains elusive.
Objective
To compare, in a large and heterogeneous cohort of healthy females and males, the commonly used intensity classification system (i.e., light, moderate, vigorous, near-maximal) based on fixed ranges of metabolic equivalents (METs) to an individualized schema based on the exercise intensity domains (i.e., moderate, heavy, severe).
Methods
A heterogenous sample of 565 individuals (females 165; males 400; age range 18–83 years old) were included in the study. Individuals performed a ramp-incremental exercise test from which gas exchange threshold (GET), respiratory compensation point (RCP) and maximum oxygen uptake (VO2max) were determined to build the exercise intensity domain schema (moderate = METs ≤ GET; heavy = METs > GET but ≤ RCP; severe = METs > RCP) for each individual. Pearson’s chi-square tests over contingency tables were used to evaluate frequency distribution within intensity domains at each MET value. A multi-level regression model was performed to identify predictors of the amplitude of the exercise intensity domains.
Results
A critical discrepancy existed between the confines of the exercise intensity domains and the commonly used fixed MET classification system. Overall, the upper limit of the moderate-intensity domain ranged between 2 and 13 METs and of the heavy-intensity domain between 3 and 18 METs, whereas the severe-intensity domain included METs from 4 onward.
Conclusions
Findings show that the common practice of assigning fixed values of METs to relative categories of intensity risks misclassifications of the physiological stress imposed by exercise and physical activity. These misclassifications can lead to erroneous interpretations of the dose–response relationship of exercise and physical activity
A critical evaluation of current methods for exercise prescription in women and men
No full textCommon methods to prescribe exercise intensity are based on fixed percentages of maximum rate of oxygen uptake (V ̇O2max), peak work rate (WRpeak), maximal HR (HRmax). However, it is unknown how these methods compare to the current models to partition the exercise intensity spectrum.
Purpose: Thus, the aim of this study was to compare contemporary gold-standard approaches for exercise prescription based on fixed percentages of maximum values to the well-established, but underutilized, "domain" schema of exercise intensity.
Methods: One hundred individuals participated in the study (women, 46; men, 54). A cardiopulmonary ramp-incremental test was performed to assess V ̇O2max, WRpeak, HRmax, and the lactate threshold (LT), and submaximal constant-work rate trials of 30-min duration to determine the maximal lactate steady-state (MLSS). The LT and MLSS were used to partition the intensity spectrum for each individual in three domains of intensity: moderate, heavy, and severe.
Results: V ̇O2max in women and men was 3.06 ± 0.41 L·min and 4.10 ± 0.56 L·min, respectively. Lactate threshold and MLSS occurred at a greater %V ̇O2max and %HRmax in women compared with men (P < 0.05). The large ranges in both sexes at which LT and MLSS occurred on the basis of %V ̇O2max (LT, 45%-74%; MLSS, 69%-96%), %WRpeak (LT, 23%-57%; MLSS, 44%-71%), and %HRmax (LT, 60%-90%; MLSS, 75%-97%) elicited large variability in the number of individuals distributed in each domain at the fixed-percentages examined.
Conclusions: Contemporary gold-standard methods for exercise prescription based on fixed-percentages of maximum values conform poorly to exercise intensity domains and thus do not adequately control the metabolic stimulus
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
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