Performance and emissions data of an internal combustion engine operating with different ethanol/water mixtures and compression ratios.

This study presents performance and emissions data of an Otto cycle mono-cylinder combustion engine operating with two different compression rates and several mixtures of anhydrous ethanol fuel and water. The instrumented engine was mounted on a dynamometer with the ignition point and injection fuel advance calibrated to obtain the maximum torque and mixture in stoichiometric conditions. Characteristic engine performance parameters and emission fractions from its exhaust system were acquired from 2,000 rpm to 4,000 rpm with fuel mixtures of up to 50% water content. To our knowledge, data on this extreme operating condition are not available in the literature.

ANTEROMEDIAL OR CENTRAL ANATOMIC ACL RECONSTRUCTION? A CADAVERIC HIP-TO-TOE STUDY.

Objective: To compare anatomic anterior cruciate ligament (ACL) reconstruction between two tunnel positions in knees with isolated ligament tears. Methods: Anatomic ACL reconstruction was performed, from hip-to-toe, on 15 fresh cadaveric specimens. No associated lesions were created to enhance knee instability. The protocol was conducted in three states: (1) complete isolated ACL deficiency; (2) anatomic femoral and tibial anteromedial ACL reconstruction (AM REC); and (3) anatomic femoral and tibial central ACL reconstruction (Central REC). The reconstruction protocols were randomly assigned. The continuous mechanized pivot-shift test was recorded dynamically with a tracking system. Results: The Central REC group showed a smaller degree of internal rotation (0.6° ± 0.3° vs. 1.8° ± 0.3°, respectively, P < 0.05) and no difference in anterior translation (4.7 mm ± 0.4 mm vs. 4.5 mm ± 0.4 mm, respectively, P > 0.05) in the pivot-shift test, compared with the AM REC group. Conclusion: The central anatomic ACL reconstruction resulted in greater restriction of internal rotation than the anteromedial anatomic ACL reconstruction. Experimental Study on Cadaver.

Objetivo: Comparar a reconstrução anatômica do ligamento cruzado anterior (LCA) entre duas posições de túnel em joelhos com lesões isoladas do ligamento. Métodos: A reconstrução anatômica do LCA foi realizada, do quadril aos pés, em 15 peças anatômicas de cadáveres frescos. Não foram criadas lesões associadas para intensificar a instabilidade do joelho. O protocolo foi realizado em três estados: (1) deficiência isolada completa do LCA; (2) reconstrução anatômica femoral e anteromedial tibial do LCA (AM REC); e (3) reconstrução anatômica femoral e central tibial do LCA (Central REC). Os protocolos de reconstrução foram atribuídos aleatoriamente. O teste de pivot-shift mecanizado contínuo foi registrado dinamicamente com um sistema de rastreamento. Resultados: O grupo Central REC apresentou menor grau de rotação interna (0,6° ± 0,3° vs. 1,8° ± 0,3°, respectivamente, p < 0,05) e nenhuma diferença na translação anterior (4,7 mm ± 0,4 mm vs. 4,5 mm ± 0,4 mm, respectivamente, p > 0,05) no teste de pivot-shift, comparado ao grupo AM REC. Conclusão: A reconstrução anatômica central tibial do LCA resultou em maior restrição da rotação interna do que a reconstrução anteromedial tibial do LCA. Estudo em Cadáver Experimental.

Behavior of skin temperature during incremental cycling and running indoor exercises.

The study of the human body's energy behavior has received more attention over the past years. The development of thermal infrared cameras brought new possibilities for evaluating physical exercise performance. This work aims to study the skin temperature distribution during treadmill running and cycle ergometer tests with a graded load exercise until exhaustion. Eight amateur athletes performed both tests. In addition, the ventilatory and metabolic data were measured by indirect calorimetry. The thermoregulatory system is highly requested to maintain the internal body temperature. Consequently, the average skin temperature decreased during running and cycling tests, although with a higher variation in running. It was observed that the lower limbs had a similar performance for both exercises; on the other hand, the upper limbs had a higher temperature decrease for running. This may be explained by increased body energy transfer to the environment due to higher degrees of freedom during the test. The main contribution is comparing the thermal behavior of the person's skin performing two different activities, constructing a basis for future energy and exergy analysis of the human body under physical activities complementary to the literature.

Phenomenological and Thermodynamic Model of Gas Exchanges in the Placenta during Pregnancy: A Case Study of Intoxication of Carbon Monoxide.

The present work simulates the transport of oxygen, carbon dioxide, and carbon monoxide between a fetus's circulatory system and the mother's. The organ responsible for this exchange is the placenta. Carbon monoxide is a common air pollutant, and it impacts the physiological conditions even in low concentration. The impacts of carbon monoxide are especially dangerous for pregnant women, fetuses, and newborn babies. A model of carbon monoxide transport, from the literature, is modified to simulate a pregnant woman (original model was a male), therefore changing some parameters to express the adjusted respiratory system. It was considered the gas exchange in the placenta, to evaluate the concentration of these different gases in the fetus arterial and venous blood. Three methods of the exergy analysis are implemented for both mother and fetus respiratory systems, aiming at the comparison with the respiratory system of a male adult. The destroyed exergy of the literature did not have the same trend as the models proposed in this article, taking into consideration the hemoglobin reactions. In contrast, the entropy generation associated only with the diffusion transport phenomena was one order of magnitude lower than the other methods. The placenta destroyed exergy rate is significantly higher compared to the irreversibilities of the mother's respiratory system. One possible explanation is the fact that the placenta has other physiological functions than gas transportation.

The Effect of Carbon Monoxide on the Exergy Behavior of the Lungs.

The present work evaluates the impact of carbon monoxide (CO) inhalation on the human lung's exergy behavior by considering different levels of intoxication and amounts of hemoglobin. Its impact is significant because CO is one of the most common air pollutants in cities and an increase in destroyed exergy may be correlated with lifespan reduction or the malfunctioning of certain human organs. An evaluation of the severity of intoxication as a function of city altitude may intensify the hazard associated with carbon monoxide. A computational model of human lungs obtained from the literature was used to calculate the concentrations of oxygen (O2), carbon monoxide (CO), and carbon dioxide (CO2) in the respiratory system. With the purpose of better evaluating the different levels of CO intoxication and hemoglobin concentration (which is a function of acclimatization time and some pathologies, such as anemia), a model calculating exergy efficiency for the lungs was proposed. From this model, it was possible to conclude that a higher level of intoxication is associated with lower exergy efficiency values. When associated with carbon monoxide intoxication, higher hemoglobin levels also result in lower efficiency. Eventually, a comparison between previous studies and the current study was carried out, regarding the method employed to calculate the exergy destroyed in the lungs, considering not only gas transport, but also hemoglobin concentration and its reaction with the gases from a second law perspective.

Clinical application of thermography for energy balance in athletes - state of the art and new paradigms / Aplicação clínica da termografia para equilibrio energético em atletas - estado da arte e novos paradigmas / Aplicación clínica de la termografia para equilibrio energético en atletas - estado del arte y nuevos paradigmas

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.

Este artigo descreve a evolução de técnicas que possibilitaram a aplicação adequada das Leis da Termodinâmica às atividades físicas e aos atletas. O objetivo é propor indicadores de desempenho que ajudem a acrescentar informações aos índices atuais usados em medicina e nos esportes, como o limiar de lactato e o consumo máximo de oxigênio. Diversas análises dos resultados obtidos pelo grupo foram realizadas com essa finalidade. Além disso, procedeu-se à análise da discussão sobre quais técnicas proporcionariam resposta melhor às medições. Alguns exemplos são a substituição do teste de corrida em esteira pela bicicleta ergométrica (que sabidamente, pode ser usada para o trabalho), e a pesquisa da literatura para medir a temperatura interna com maior precisão. Nível de Evidência V; Opinião de especialista.

Este artículo describe la evolución de técnicas que posibilitaron la aplicación adecuada de las Leyes de la Termodinámica a las actividades físicas y a los atletas. El objetivo es proponer indicadores de desempeño que ayuden a acrecentar informaciones a los índices actuales usados en medicina y en los deportes, como el umbral de lactato y el consumo máximo de oxígeno. Fueron realizados diversos análisis de los resultados obtenidos por el grupo con esa finalidad. Además, se procedió al análisis de la discusión sobre qué técnicas proporcionarían respuesta mejor a las mediciones. Algunos ejemplos son la sustitución del test de carrera en cinta por la bicicleta ergométrica (que sabidamente, puede ser usada para el trabajo), y la investigación de la literatura para medir la temperatura interna con mayor precisión. Nivel de Evidencia V; Opinión de especialista.

Exergy Analysis of the Musculoskeletal System Efficiency during Aerobic and Anaerobic Activities.

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.

Post-analysis methods for lactate threshold depend on training intensity and aerobic capacity in runners. An experimental laboratory study / Métodos de pós-análise do limiar do lactato dependem da intensidade de treinamento e da capacidade aeróbica dos corredores. Um estudo laboratorial experimental

ABSTRACT CONTEXT AND OBJECTIVE: This study aimed to evaluate different mathematical post-analysis methods of determining lactate threshold in highly and lowly trained endurance runners. DESIGN AND SETTING: Experimental laboratory study, in a tertiary-level public university hospital. METHOD: Twenty-seven male endurance runners were divided into two training load groups: lowly trained (frequency < 4 times per week, < 6 consecutive months, training velocity ≥ 5.0 min/km) and highly trained (frequency ≥ 4 times per week, ≥ 6 consecutive months, training velocity < 5.0 min/km). The subjects performed an incremental treadmill protocol, with 1 km/h increases at each subsequent 4-minute stage. ­Fingerprint ­blood-lactate analysis was performed at the end of each stage. The lactate threshold (i.e. the running velocity at which blood lactate levels began to exponentially increase) was measured using three different methods: increase in blood lactate of 1 mmol/l at stages (DT1), absolute 4 mmol/l blood lactate concentration (4 mmol), and the semi-log method (semi-log). ANOVA was used to compare different lactate threshold methods and training groups. RESULTS: Highly trained athletes showed significantly greater lactate thresholds than lowly trained runners, regardless of the calculation method used. When all the subject data were combined, DT1 and semi-log were not different, while 4 mmol was significantly lower than the other two methods. These same trends were observed when comparing lactate threshold methods in the lowly trained group. However, 4 mmol was only significantly lower than DT1 in the highly trained group. CONCLUSION: The 4 mmol protocol did not show lactate threshold measurements comparable with DT1 and semi-log protocols among lowly trained athletes.

RESUMO CONTEXTO E OBJETIVO: O objetivo do presente estudo é avaliar modelos matemáticos de pós-análise do limiar de lactato em grupos de corredores de longa distância muito ou pouco treinados. TIPO DE ESTUDO E LOCAL: Estudo laboratorial experimental. Hospital Público Universitário Terciário. MÉTODO: Vinte e sete corredores homens foram divididos em: pouco treinados (frequência < 4 vezes por semana, < 6 meses, velocidade ≥ 5,0 minutos/km) e muito treinados (frequência ≥ 4 vezes por semana, ≥ 6 meses, velocidade < 5,0 minutos/km). Os participantes foram submetidos a protocolo de esteira escalonado (1% inclinação) = 1 km/h por fase (4 minutos). Ao fim de cada estágio, análise da "impressão digital" metabolômica foi realizada. O limiar do lactato (i.e. velocidade em que o lactato sanguíneo aumenta exponencialmente) foi medido utilizando-se três métodos: aumento de 1 mmol/l da concentração, concentração absoluta de 4 mmol e método semi-log. ANOVA foi utilizada para comparar os diferentes limiares de lactato e grupos. RESULTADO: Atletas muito treinados apresentaram limiares de lactato maiores que os corredores pouco treinados, independentemente do método de cálculo utilizado. Comparando todos os corredores juntos, as análises de aumento de 1 mmol/l e semi-log não foram diferentes, enquanto a concentração absoluta de 4 mmol/l foi significativamente mais baixa que as dos dois outros métodos. Essas mesmas tendências foram observadas ao se compararem os métodos de limiar de lactato no grupo menos treinado. Entretanto, a análise absoluta de 4 mmol/l foi menor do que a do aumento de 1 mmol/l no grupo muito treinado. CONCLUSÃO: O método concentração absoluta de 4 mmol não mostrou mensurações comparáveis de limiar do lactato quando comparado com os protocolos aumento de 1 mmol/l e semi-log nos atletas pouco treinados.

Post-analysis methods for lactate threshold depend on training intensity and aerobic capacity in runners. An experimental laboratory study.

CONTEXT AND OBJECTIVE: This study aimed to evaluate different mathematical post-analysis methods of determining lactate threshold in highly and lowly trained endurance runners. DESIGN AND SETTING: Experimental laboratory study, in a tertiary-level public university hospital. METHOD: Twenty-seven male endurance runners were divided into two training load groups: lowly trained (frequency < 4 times per week, < 6 consecutive months, training velocity ≥ 5.0 min/km) and highly trained (frequency ≥ 4 times per week, ≥ 6 consecutive months, training velocity < 5.0 min/km). The subjects performed an incremental treadmill protocol, with 1 km/h increases at each subsequent 4-minute stage. -Fingerprint -blood-lactate analysis was performed at the end of each stage. The lactate threshold (i.e. the running velocity at which blood lactate levels began to exponentially increase) was measured using three different methods: increase in blood lactate of 1 mmol/l at stages (DT1), absolute 4 mmol/l blood lactate concentration (4 mmol), and the semi-log method (semi-log). ANOVA was used to compare different lactate threshold methods and training groups. RESULTS: Highly trained athletes showed significantly greater lactate thresholds than lowly trained runners, regardless of the calculation method used. When all the subject data were combined, DT1 and semi-log were not different, while 4 mmol was significantly lower than the other two methods. These same trends were observed when comparing lactate threshold methods in the lowly trained group. However, 4 mmol was only significantly lower than DT1 in the highly trained group. CONCLUSION: The 4 mmol protocol did not show lactate threshold measurements comparable with DT1 and semi-log protocols among lowly trained athletes.

3D computer tomography for measurement of femoral position in acl reconstruction.

OBJECTIVE: To validate intra- and inter-class correlation coefficients of a transparent 3D-TC protocol and investigate relationships between different axial rotations. METHODS: Twenty unilateral knee TCs (iSite - Philips) were evaluated by means of a transparent 3D-TC OsiriX Imaging Software (v.3.9.4), 3D MPR protocol. Mathematical model of femoral tunnel projections acquired on vertical and horizontal rotations from -20 to +20 degrees. Height (h'/H) and length (t'/T) of tunnel projections have been analyzed by the Bernard and Hertel's method. STATISTICS: power of study=80%, ICC, ANOVA, p<0.05 (SPSS-19). RESULTS: Transparent 3D-TC showed high reliability of both intra-observer (h'/H=0.941; t'/T=0.928, p<0.001) and inter-observer (h'/H=0.921; t'/T=0.890, p<0.001) ICC. ACL Length (t'/T) and Height (h'/H) projections were statistically different on vertical and horizontal rotations: p=0.01 and p<0.001, respectively. CONCLUSION: This new transparent 3D-TC protocol is an accurate and reproducible method that can be applied for ACL femoral tunnel or footprint measurement with high ICC reliability. Level of Evidence II, Descriptive Laboratory Study.

Description of an evaluation system for knee kinematics in ligament lesions, by means of optical tracking and 3D tomography,

Objective: To describe and demonstrate the viability of a method for evaluating knee kine matics, by means of a continuous passive motion (CPM) machine, before and after anterio cruciate ligament (ACL) injury. Methods: This study was conducted on a knee from a cadaver, in a mechanical pivot-shif simulator, with evaluations using optical tracking, and also using computed tomography. Results: This study demonstrated the viability of a protocol for measuring the rotation an translation of the knee, using reproducible and objective tools (error<0.2mm). The mech anized provocation system of the pivot-shift test was independent of the examiner an always allowed the same angular velocity and traction of 20 N throughout the movement. Conclusion: The clinical relevance of this method lies in making inferences about the in viv behavior of a knee with an ACL injury and providing greater methodological quality in futur studies for measuring surgical techniques with grafts in relatively close positions...

Objetivo: Descrever e demonstrar a viabilidade de um método de avaliação da cinemática do joelho, por meio de um aparelho de CPM (continuous passive motion), antes e após a lesão do ligamento cruzado anterior (LCA). Métodos: O estudo foi feito em joelho de cadáver, em um simulador mecânico de pivot-shift avaliado a partir de rastreamento óptico associado à tomografia computadorizada. Resultados: Este estudo demonstra a viabilidade de um protocolo de mensuração de rotação e translação do joelho com ferramentas reprodutíveis e objetivas (erro < 0,2 mm). O sistema mecanizado de provocação do teste do pivot-shift é independente do examinador e permite sempre a mesma velocidade angular e tração de 20 N por todo o movimento. Conclusão: Sua relevância clínica está em fazer inferências sobre o comportamento in vivo de um joelho com lesão do LCA e proporcionar aos estudos futuros maior qualidade metodológica para a aferição de técnicas cirúrgicas com enxertos em posições relativamente próximas...

Description of an evaluation system for knee kinematics in ligament lesions, by means of optical tracking and 3D tomography.

OBJECTIVE: To describe and demonstrate the viability of a method for evaluating knee kinematics, by means of a continuous passive motion (CPM) machine, before and after anterior cruciate ligament (ACL) injury. METHODS: This study was conducted on a knee from a cadaver, in a mechanical pivot-shift simulator, with evaluations using optical tracking, and also using computed tomography. RESULTS: This study demonstrated the viability of a protocol for measuring the rotation and translation of the knee, using reproducible and objective tools (error < 0.2 mm). The mechanized provocation system of the pivot-shift test was independent of the examiner and always allowed the same angular velocity and traction of 20 N throughout the movement. CONCLUSION: The clinical relevance of this method lies in making inferences about the in vivo behavior of a knee with an ACL injury and providing greater methodological quality in future studies for measuring surgical techniques with grafts in relatively close positions.

OBJETIVO: Descrever e demonstrar a viabilidade de um método de avaliação da cinemática do joelho, por meio de um aparelho de CPM (continuous passive motion), antes e após a lesão do ligamento cruzado anterior (LCA). MÉTODOS: O estudo foi feito em joelho de cadáver, em um simulador mecânico de pivot-shift avaliado a partir de rastreamento óptico associado à tomografia computadorizada. RESULTADOS: Este estudo demonstra a viabilidade de um protocolo de mensuração de rotação e translação do joelho com ferramentas reprodutíveis e objetivas (erro < 0,2 mm). O sistema mecanizado de provocação do teste do pivot-shift é independente do examinador e permite sempre a mesma velocidade angular e tração de 20 N por todo o movimento. CONCLUSÃO: Sua relevância clínica está em fazer inferências sobre o comportamento in vivo de um joelho com lesão do LCA e proporcionar aos estudos futuros maior qualidade metodológica para a aferição de técnicas cirúrgicas com enxertos em posições relativamente próximas.