1,720,956 research outputs found
Estimation of the maximal heart rate for exercise prescription in heart failure patients: are we there yet?
No full textExercise prescription for heart failure (HF) is a cornerstone for a clinically effective and safe cardiac rehabilitation (CR) programme. 1,2 Likewise, the prescription of the intensity according to the ventilatory thresholds, identified by cardiopulmonary exercise testing (CPET), is considered an optimal method. 2-4 Although with lower accuracy, when CPET is not available, a percentage of the measured maximal heart rate (MHR) during an exercise stress test (EST) is considered the minimum standard in recent CR guidelines worldwide. 2,3 However, professionals must be prepared to safely assess and monitor patients when this assessment is unavailable 5 since the evidence shows that most centres are still not performing this evaluation prior to beginning CR. 6 Thus, in the absence of maximal tests (CPET or EST) or a submax-imal volitional test (field and submaximal tests), the rating of perceived exertion and the talk test are two commonly recommended techniques to estimate the intensity for appropriate exercise prescription since the determination according to a percentage of the predicted MHR can be highly divergent in HF patients, mainly due to negative chronotropic influence of the beta-blockers, and disease-related dysfunctions. 2 A recent study by Magrì et al. 7 developed a new equation for MHR prediction in HF patients with reduced left ventricular ejection fraction (LVEF) and treated with beta-blockers. According to this cohort including 3487 stable HF subjects, the equation utilizes four variables [e.g. age, rest heart rate (HR), LVEF, and anaemia], as following [MHR = (109-(0.5 × age) + (0.5 × rest HR) + (0.2 × LVEF)-(5 if haemoglobin <11 g/ dL)]. The derived equation improved historical and cohort-based, most routinely used formulas, which can be valuable to determine the real maximal effort during an EST when the CPET is unavailable. The authors also concluded that a percentage range of 75-80% of the MHR, deriving from the new equation, might help to identify the intensity domains during a CR programme. The authors are applauded for the massive amount of work that has been put into this study, aiming to provide a clinically relevant toll with the best accuracy possible to be utilized in daily practice; however, despite the unquestionable relevance of the research, we felt that its indiscriminate use for exercise prescription should be evaluated with caution. Although more acceptable, the coefficient of determination provided with the new equation remained low (r 2 = 0.24) and the standard error high (17.5 b.p.m.), indicating that independent selected variables (age, rest HR, LVEF, and anaemia) are not explaining much the variation on the MHR for the majority of the patients (76%). The increased dispersion may generate substantial imprecision in exercise prescription domain identification, hereby potentially precluding its large-scale clinical use, particularly on those with different phenotypes and co-morbidities than those assessed in the study. Hansen et al. 8 have already demonstrated that even the intensity domains prescribed according to a percentage of a measured MHR can be extremely incompatible with the current guideline-based recommendations due to individual HR scattering in response to exercise. Likewise, an exercise intensity determination according to an estimated MHR can generate greater inconsistencies , lowering CR prescription accuracy, which may also decrease safety and efficacy. Hence, considering the importance of assessing the reproducibility and generalizability of prediction models, we felt that external validation of the equation from Magrì et al. 7 could be relevant. To assess the new equation applicability, we obtained the MHR of a sample of 191 HF patients with reduced LVEF (age: 55.8 ± 13.7 years; 69.6% male; body mass index 27.0 ± 4.5 kg/m 2) retrospectively assessed on treadmill CPET exams performed in a private outpatient cardiologic clinic in Brazil. These data are part of a multicentric study, approved by the institutional review board under number CAAE: 35706720.4.0000.8093. All patients continued beta-blocker treatment and achieved maximal effort (respiratory exchange ratio of 1.05 or higher) during the stress test and were in sinus rhythm. Heart failure was secondary to coronary artery disease in 51.3% of the cohort, with an average LVEF of 38.3 ± 6.7%. Conclusively, the median and interquartile range of the measured MHR was 135 (114-155) b.p.m., while the estimated MHR by Keteyian et al. 9 was 119 (114-126) b.p.m. and by the new equation 7 121 (116-128) b.p.m. These groups were compared by the post hoc for multiple comparisons as appropriate. Interestingly, the estimated MHR from both formulas (Keteyian et al. 9 and the new formula 7) were not statistically different from each other (P = 0.11), and the measured MHR was different from both estimation's formulas (P < 0.01 and P < 0.01). The association between measured and estimated MHR was assessed by the Spearman correlation coefficient, which revealed a moderate correlation between the measured and estimated values (rho = 0.576 for Keteyian and 0.592 for Magrì). Finally, the agreement between the measured and estimated MHR, assessed byFinancial partial support for this work was provided by public research grants and scholarships from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Teste Cardiopulmonar em Pacientes Pós-COVID-19: De Onde vem a Intolerância ao Exercício?
No full textPost-COVID-19 exercise intolerance is poorly understood. Cardiopulmonary exercise testing (CPET) can identify the underlying exercise limitations
Reference Standards for Cardiorespiratory Fitness in Brazil. A Pooled Analysis and Overview of Heterogeneity in National and International Studies
No full textThis study aimed to propose reference standards for cardiorespiratory fitness (CRF) for Brazil from a pooled analysis and to compare peak oxygen uptake (V˙ o2peak ) in Brazilian, United States (US), and Norwegian samples, exploring possible national and international differences
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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