Influencia de la longitud de la biela en la eficiencia y biomecánica del pedaleo submáximo

El principal objetivo de este estudio es analizar el efecto de pequeños cambios en la longitud de la biela en el gasto energético y la técnica de pedaleo submáximo. Participaron 12 ciclistas de fondo en carretera bien entrenados, que realizaron pruebas de pedaleo a tres potencias con cadencia estable, utilizando tres longitudes de biela (en orden aleatorio). Sus bicicletas fueron exactamente reproducidas en un ergómetro que medía el torque ejercido sobre la biela izquierda y derecha de forma independiente. Simultáneamente se registró cinemática 2D de la pierna derecha y el gasto energético al pedalear (eficiencia gruesa). Los resultados muestran que los cambios en la longitud de la biela no tuvieron efecto en la eficiencia gruesa, pero sí en las variables biomecánicas. Una biela de mayor longitud provocó una pérdida de eficiencia mecánica y un aumento en la flexión y el rango de movimiento de la cadera y la rodilla, sin cambios en el tobillo. Aunque estos cambios no fueron lo suficientemente importantes para alterar la eficiencia gruesa, sí que podrían tener implicaciones negativas a largo plazo (peor técnica de pedaleo y riesgo de lesión). En conclusión, el efecto de pequeños cambios en la longitud de la biela, que serían asumibles por ciclistas de competición, producen alteraciones en la biomecánica de pedaleo, pero no en su eficiencia gruesa. Futuros estudios deben abordar los efectos a largo plazo de estos cambios.The main purpose of this study was to analyze the effects of small changes in crank length on gross efficiency and pedaling technique during submaximal cycling. Twelve well-trained road cyclists participated. They pedaled at three power outputs and steady cadence with three crank lengths (in a randomized order). Their bicycles were exactly reproduced on an ergometer where crank torque of the left and right legs were independently registered. 2D kinematic of the right leg and energy cost (gross efficiency) were recorded. The results showed that changes in crank length had no effect on the gross efficiency, but had effect on the biomechanical variables. A longer crank caused a decreased in mechanical efficiency and an increase in the flexion and range of movement of the hip and the knee, without changes in the ankle. These alterations were not significant enough to alter the gross efficiency, but they could have negative long-term implications (worse pedaling technique and possible injuries). In conclusion, the small changes in crank arm length which are feasible for competitive cyclists affected cycling biomechanics, but not gross efficiency. Future studies should study long-term effects of these changes.Peer Reviewe

Contextual intelligence and expertise in soccer

Para los entrenadores la inteligencia en el juego es uno de los intangibles que predicen el éxito en la competición. De ahí que el objetivo de este estudio fuera analizar la percepción que jugadores de fútbol de diferente nivel de pericia tenían de su inteligencia para el juego. Se aplicó el Cuestionario de Inteligencia Contextual en el Deporte (ICD) que evalúa tres dimensiones: Inteligencia Anticipatoria, Inteligencia Táctica e Inteligencia Competitiva. En este estudio participaron 690 jugadores de fútbol de diferente nivel competitivo. Los resultados mostrarion que a medida que aumentaba el nivel competitivo se incrementaba la percepción de los jugadores sobre su inteligencia contextual. Este estudio confirma el papel que para los jugadores posee el sentirse competentes para solucionar los problemas tácticos de su deporte y que este sentimiento aumenta con su nivel de competencia.Coaches consider that game intelligence is one of the main elements that can predict success in competition. The objective of this study was to analize the perceptions that soccer players of different level of expertise had about their intelligence in the field. The Contextual Intelligence Questionnaire (ICD) was applied to a sample of spanish soccer players. This instrument evaluate three dimensions: Anticipatory intelligence, Tactical Intelligence and Competitive Intelligence. Six hundred and ninety of spanish soccer players of different level of expertise, participated in this study. Results showed that this self-perception increased with the level of players. This study confirmed the relevance of feeling able of solving tactical problems in the game, and how this feeling increase with the level of expertise.El presente estudio se pudo llevar a cabo gracias a la ayuda a la investigación concedida por la Cátedra Real Madrid- Universidad Europea de Madrid en su convocatoria 201

Patrón de comportamiento tipo A, ira y enfermedades cardiovasculares (ECV) en población urbana chilena

Diaz, EM (Moyano Diaz, Emilio)1; Icaza, G (Icaza, Gloria); Mujica, V (Mujica, Veronica); Nunez, L (Nunez, Loreto); Leiva, E (Leiva, Elba); Vasquez, M (Vasquez, Marcela); Palomo, I (Palomo, Ivan)A worldwide raise in the number of cardiovascular disease (CVD) and the existence of a higher percentage in Maule (Chile) than the national media, and increased attention in the analysis of psychological factors motivate to analyze the Type A Behavior Pattern (TABP) and anger in relation to CVD. The sample was 1007 adults between 18 and 74 years old (citizens of Talca, Chile), mostly women. They provided information about their demographic details, eating habits and lifestyle, answered the Novaco's Anger inventory and the Retiro Scale of Type A Behavior (RSTAB), and also were taken measurements like weight, body mass index and blood pressure and blood tests related to risk factors to traditional cardiovascular diseases. The results show Overall, that the participants appear highly sedentary (79.9%) with relatively high levels of tabaquism (53.6%), and hypercholesterolemia (44.5%), overweight (40.7%) and obesity (32.6%). A quarter of the sample also presents hyperglycemic indexes, hypertension and TABP unequally distributed by sex. The absence of PCTA (or PCTB presence) appeared mostly associated with traditional cardiovascular risk factors (CRF). Regarding anger, women present more high than men (2.1% against 0.3%; c(2)(3) = 27.99,p<.0001), decreasing for both sexes with age, while also befall stroke by sex

Carbon sequestration offsets a large share of GHG emissions in dehesa cattle production

The contribution of cattle production to climate change is increasingly recognized, and there is a need to identify those systems minimizing emissions and maximizing carbon (C) sinks. In the Southwest of the Iberian Peninsula, cattle are produced on dehesa agroforestry systems, where cows and calves graze together until weaning, and calf fattening is based on external feed. The aim of this study was to assess the Carbon footprint (CF) of beef of this extensive production system using Life Cycle Assessment (LCA) methodology. The study collects data from 15 extensive cattle farms, 6 organically (ORG) and 9 conventionally (CONV) managed; 4 farms had their own fattening facilities while most of the farms sold calves to 2 specialised fattening farms also studied. CF calculation includes field monitoring of C sequestration on soils and woody biomass in a selection of well-known points with previous estimations. The limit of the system was “cradle to gate”, and the functional unit was 1 kg LW of calf at slaughtering age. The main C sinks of the dehesa system sequestered an average of 3.3 t CO2eq ha−1 year−1. The average CF of the final product was 6.43 ± 21.46 kg CO2eq kgLW−1, with numerically lower but not statistically different average CF in ORG than in CONV systems. The inclusion of C sequestration, that averaged −13.52 kg CO2eq kgLW−1, offset 95% and 54% on ORG and CONV farms, respectively. In some cases, C sequestration compensated all GHG emissions and resulted in negative CF. There was a direct negative relationship between CF and stocking rate, leading to negative CF values in those farms with lowest stocking rates

Prevalencia de factores de riesgo cardiovascular clásicos en población adulta de Talca, Chile, 2005

Departamento de Bioquímica Clínica e Inmunohematología, Facultad de Ciencias de la Salud, Universidad de Talca, Talca, Chile. Instituto de Matemática y Física, Universidad de Talca, Talca, Chile. Departamento de Salud Pública, Facultad de Ciencias de la Salud, Universidad de Talca, Talca, Chile. Escuela de Psicología, Universidad de Talca, Talca, Chile.Background: Cardiovascular disease (CVD) has several traditional risk factors (RF), and some of them are potentially modifiable. Aim: To determine the prevalence of most common risk factors in adult population in Talca in Central Chile. Subjects and methods: We studied 1007 subjects aged 18 to 74 years (66% women), living in Talca, selected by a probability sampling. They answered a questionnaire and anthropometry, blood pressure, lipid profile and blood glucose were measured. Results: Thirty seven percent of subjects smoked, 70.1% had a body mass index over 25 kg/m2 and 41% had an abnormally high circumference. High blood pressure was found in 37% (36% of these subjects were unaware of this condition), 44.5% had hypercholesterolemia, 21.5% had low HDL cholesterol, 40.1% had hypertriglyceridemia and 26.3% had high blood glucose levels. Conclusions: There is a high prevalence of risk factors for CVD in adult population from Talca. The prevalence of risk factors is higher than that reported by the 2003 National Health Survery

CONTAGION OF US SUBPRIME MORTGAGE CRISIS TO COLOMBIAN ECONOMY: MEASURED BY FINANCIAL MARKET DATA

The long-horizon event study methodology is used to document the severe impact of the US subprime mortgage crisis on the Colombian economy. The estimated parameter of a constantmean return model is used to derive the &ldquo;abnormal return&rdquo; on the market portfolios of Colombia over its selected event window. Analyses of the results reveal that the US subprime mortgage crisis negatively affected both the Colombian and the US equity markets almost identically in terms of cumulative percentage reductions and timing. Statistic testing results seem to support the qualitative observation. This phenomenon can be attributable to the recent multilateral and regional trade agreements that increase the flow of trade and foreign direct investment to Colombia.El estudio metodol&oacute;gico de horizonte largo es usado para documentar el impacto severo de la crisis de la finca ra&iacute;z de Estados Unidos en la Econom&iacute;a Colombiana. El par&aacute;metro estimado de la constante del retorno del modelo es usado para derivar el retorno anormal en el mercado de portafolios sobre su selecci&oacute;n de la ventana de evento. An&aacute;lisis de estos resultados revelan que la crisis de la finca ra&iacute;z en Estados Unidos afect&oacute; negativamente ambos mercados de acciones en Estados Unidos y Colombia casi id&eacute;nticamente en t&eacute;rminos de reducci&oacute;n de porcentaje cumulativo y tiempo. Resultados de pruebas estad&iacute;sticas parecen soportar la observaci&oacute;n. Este fen&oacute;meno puede ser atribuido a los recientes acuerdos de comercio multilaterales y regionales que incrementan el flujo de comercio e inversi&oacute;n extranjera directa a Colombia

Pathogenic mechanisms implicated in the intravascular coagulation in the lungs of BVDV-infected calves challenged with BHV-1

Resistance to respiratory disease in cattle requires host defense mechanisms that protect against pathogens which have evolved sophisticated strategies to evade them, including an altered function of pulmonary macrophages (MΦs) or the induction of inflammatory responses that cause lung injury and sepsis. The aim of this study was to clarify the mechanisms responsible for vascular changes occurring in the lungs of calves infected with bovine viral diarrhea virus (BVDV) and challenged later with bovine herpesvirus type 1 (BHV-1), evaluating the role of MΦs in the development of pathological lesions in this organ. For this purpose, pulmonary lesions were compared between co-infected calves and healthy animals inoculated only with BHV-1 through immunohistochemical (MAC387, TNFα, IL-1α, iNOS, COX-2 and Factor-VIII) and ultrastructural studies. Both groups of calves presented important vascular alterations produced by fibrin microthrombi and platelet aggregations within the blood vessels. These findings were earlier and more severe in the co-infected group, indicating that the concomitance of BVDV and BHV-1 in the lungs disrupts the pulmonary homeostasis by facilitating the establishment of an inflammatory and procoagulant environment modulated by inflammatory mediators released by pulmonary MΦs. In this regard, the co-infected calves, in spite of presenting a greater number of IMΦs than single-infected group, show a significant decrease in iNOS expression coinciding with the presence of more coagulation lesions. Moreover, animals pre-inoculated with BVDV displayed an alteration in the response of pro-inflammatory cytokines (TNFα and IL-1), which play a key role in activating the immune response, as well as in the local cell-mediated respons

Effect of infection with BHV-1 on peripheral blood leukocytes and lymphocyte subpopulations in calves with subclinical BVD

Bovine viral diarrhea virus (BVDV) and bovine herpesvirus-1 (BHV-1) are important cattle pathogens that induce a broad immunosuppression on cell-mediated immune response on its own participating in the bovine respiratory disease complex (BRDC). The aim of our study was to evaluate the quantitative changes in immunocompetent cells in healthy calves and calves with subclinical bovine viral diarrhea (BVD), both inoculated with BHV-1. Total leukocyte counts exhibited changes mainly in neutrophils and lymphocytes that can contribute to the BVDV immunosuppression, thus accounting for some of the intergroup differences. Monocytes did not display numerical changes in either group. Regarding lymphocyte subpopulations, even though CD4+ T lymphocytes and B cells were depleted around 4 dpi in both infected groups, the main difference observed between both groups was in CD8+ T cells which displayed an earlier depletion in BVDV inoculated calves that can promote a greater BHV-1 dissemination, thus aggravating the course of the disease

Carbon Footprint of an Extensively Raised, Low-Productivity Sheep Population

Extensive traditional livestock systems currently face various threats, leading to their disappearance. An example of these extensive livestock farming systems is the production of the Lojena sheep breed in the Sierra de Loja (Granada, Spain), with a census of 24,511 ewes in 2021. The aim of this work is to calculate the carbon footprint (CF) of this local breed in this region. This study is based on data collected from 27 Lojena sheep farms producing weaned lambs (≤14 kg, 25 farms), fattened lambs (≈25 kg, 7 farms), culled animals (24 farms) and greasy wool (27 farms). Most of these farms (78%) were organically (ORG) certified and seven were conventionally (CONV) managed. The analysed farms represent 93% of the total number of farms producing Lojena sheep in the Sierra de Loja. The CF was calculated with a “cradle to farm gate” approach. The average C footprints were 27.5 } 6.8 kg CO2eq kgLW −1 for weaned lambs, 21.8 } 8.5 kg CO2eq kgLW −1 for fattened lambs, 4.1 } 2.6 kg CO2eq kgLW −1 for culled animals and 2.2 } 0.6 kg CO2eq kg−1 for greasy wool, with a not statistically different average CF in ORG than in CONV farms. Enteric fermentation represents the main source of emissions (>60%) in all the products, and external feeding (including transport, and emissions from producing the feed) represents the second one (>10%). There was an inverse relationship between CF and productivity (lambs sold ewe−1 year−1), leading to lower footprints on those farms with the higher productivity. A direct relationship between CF and stocking rate (livestock units ha−1) has been identified