Engenharia Mecânica
URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/23
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4 resultados
Resultados da Pesquisa
- Exergy analysis of the musculoskeletal system efficiency during aerobic and anaerobic activities(2018) Spanghero G.M.; Albuquerque C.; Fernandes T.L.; Hernandez A.J.; Mady C.E.K.© 2018 by the authors.The first and second laws of thermodynamics were applied to the human body in order to evaluate the quality of the energy conversion during muscle activity. Such an implementation represents an important issue in the exergy analysis of the body, because there is a difficulty in the literature in evaluating the performed power in some activities. Hence, to have the performed work as an input in the exergy model, two types of exercises were evaluated: weight lifting and aerobic exercise on a stationary bicycle. To this aim, we performed a study of the aerobic and anaerobic reactions in the muscle cells, aiming at predicting the metabolic efficiency and muscle efficiency during exercises. Physiological data such as oxygen consumption, carbon dioxide production, skin and internal temperatures and performed power were measured. Results indicated that the exergy efficiency was around 4% in the weight lifting, whereas it could reach values as high as 30% for aerobic exercises. It has been shown that the stationary bicycle is a more adequate test for first correlations between exergy and performance indices.
- Clinical application of thermography for energy balance in athletes – State of the art and new paradigms Aplicação clínica da termografia para equilíbrio energético em atletas – Estado da arte e novos paradigmas Aplicación clínica de la termografía para equilibrio energético en atletas – Estado del arte y nuevos paradigmas(2018) Fernandes T.L.; Hernandez A.J.; Albuquerque C.; Mady C.E.K.© 2018, Redprint Editora Ltda. All rights reserved.This article aims to describe the evolution of techniques that have enabled the proper application of the Laws of Thermodynamics for physical activity and athletes. The objective is to propose performance indicators to help add information to the current indices used in medicine and sports, such as the lactate threshold and maximum oxygen consumption. A number of analyses of the results obtained by the group were carried out for this purpose. Moreover, a discussion regarding which techniques would provide a better response to the measurements was analyzed. Some examples are the substitution of the treadmill running test with the stationary bicycle (known performed work), and a literature search in order to measure internal temperature more accurately. Level of Evidence V; Expert opinion.
- The effect of altitude and intensity of physical activity on the exergy efficiency of respiratory system(2014) Henriques I.B.; Mady C.E.K.; Albuquerque Neto C.; Yanagihara J.I.; Oliveira S.The effect of altitude on exercise performance of lowlanders has long been discussed, but it is still unclear whether the performance reduction is related to inefficiency of the respiratory system, body tissues or both. In the present work, exergy analysis was applied to the human body in order to compare its exergy efficiency under basal conditions and during physical activity at sea level and high altitudes for different periods of acclimatization. Two control volumes were analyzed: respiratory system and human body as a whole. Data concerning mass and energy balances of the body and respiratory system were obtained from models available in the literature, which were modified based on medical literature to simulate the responses to physical activity at high altitude for different periods of acclimatization. The results indicated that the respiratory system exergy efficiency is reduced at high altitudes and under physical activity, while exergy efficiency of the body increases for both parameters, which may indicate that the discomfort reported at high altitudes is mostly related to the respiratory system than to the other ones. Concerning the acclimatization period, its influence was more pronounced on the respiratory system.
- Exergy performance of human body under physical activities(2013) Mady C.E.K.; Albuquerque C.; Fernandes T.L.; Hernandez A.J.; Saldiva P.H.N.; Yanagihara J.I.; de Oliveira S.The aim of this work is to apply performance indicators for individuals under physical activity based on the concepts of exergy destroyed and exergy efficiency. The cardiopulmonary exercise test is one of the most used tests to assess the functional capacity of individuals with varying degrees of physical training. To perform the exergy analysis during the test, it is necessary to calculate heat and mass flow rates, associated with radiation, convection, vaporization and respiration, determined from the measurements and some relations found in the literature. The energy balance allowed the determination of the internal temperature over time and the exergy variation of the body along the experiment. Eventually, it was possible to calculate the destroyed exergy and the exergy efficiency from the exergy analysis. The exergy rates and flow rates are dependent of the exercise level and the body metabolism. The results show that the relation between the destroyed exergy and the metabolism is almost constant during the test, furthermore its value has a great dependence of the subject age. From the exergy analysis it was possible to divide the subjects according to their training level, for the same destroyed exergy, subjects with higher lactate threshold can perform more work. © 2013 Elsevier Ltd.