Electromyographical and Physiological Correlation in Patient with Heart Disease

Abstract Background: Walking is an economic activity, the more efficient the mechanical contribution, the less metabolic energy is necessary to keep walking. Patients with chronic heart failure and heart transplant present peripheral musculoskeletal disorders, dyspnea, and fatigue in their activities. Objective: In this scenario, the present study sought to verify the correlations between metabolic and electromyographic variables in chronic heart failure, heart transplant patients, and healthy controls. Methods: Regression and correlation between cost of transport and electromyographic cost, as well as correlation between oxygen consumption and muscle coactivation in patients and controls at five different walking speeds have been performed, with alpha = 0.05. Results: Strong correlation values (r controls: 0.99; chronic heart failure: 0.92; heart transplant: 0.88) indicate a linear relationship between the cost of transport and electromyographic cost. Oxygen consumption was significantly correlated to muscle activation in all groups. Conclusion: These results suggested that dynamic muscle coactivation was an important factor, especially for CHF and HT. These data support the idea that peripheral muscle limitations play an important role in people with CHF and HT. These findings indicate a strong relation between metabolic and electromyographic variables. For chronic heart failure and heart transplant patients, it can help to explain some difficulties in daily activities and aid in physical rehabilitation.

Locomoción humana: modelos y variables biomecánicas / Human locomotion: models and biomechanical variables

Resumen La locomoción con miembros implica diferentes desafíos de tipo mecánico: en cada ciclo, los segmentos deben reposicionarse anatómicamente, con fases de aceleración y deceleración y la consiguiente elevación y descenso del centro de masa. Dentro de la locomoción humana, la marcha y la carrera son actividades fundamentales en todo el ciclo vital humano. En específico, la carrera es una actividad muy estudiada por las ciencias del deporte, medicina, fisioterapia o kinesiología, ingeniería y biología, por el alto impacto articular y muscular que genera, ya que esta trae consigo lesiones y alteraciones en el rendimiento de los pacientes y deportistas. El constante estudio de la locomoción ha reconocido diferentes desafíos de tipo fisiológico y mecánico, tanto en la explicación de fenómenos como en el análisis de estos. Este artículo busca aclarar conceptos a través de textos clásicos, que se consideran básicos e importantes para entender las investigaciones posteriores. Además, se explican diferentes parámetros que sirven para comprender la locomoción, tanto en estudios con humanos como en animales. El objetivo de este trabajo es hacer una revisión de la literatura, que se enfoca en los aspectos mecánicos, energéticos, el efecto del tamaño y los diferentes patrones de la locomoción, con sus modelos mecánicos. Finalmente, los autores esperan que este texto sea un aporte para docentes y estudiantes para la comprensión de la locomoción en idioma español.

Abstract Limbed locomotion involves different mechanical challenges: in each cycle, limbs must be repositioned anatomically, with acceleration and deceleration phases and the consequent raising and lowering of the center of mass. As part of human locomotion, walking and running are fundamental activities throughout the life cycle. In particular, running has been highly studied by sports sciences, medicine, physiotherapy, kinesiology, engineering, and biology due to the high joint and muscular impact it generates, commonly causing injuries and alterations in the performance of patients and athletes. The constant study of locomotion has brought to light the different physiological and mechanical challenges when explaining and analyzing phenomena. Using classical texts, this article aims to clarify concepts considered basic and important to understand further research. In addition, different parameters needed to understand locomotion, both in human and animal studies, are explained. The objective of this paper is to review the literature focused on the mechanical and energetic aspects of locomotion, the effect of size, and the different locomotion patterns and mechanical models. Finally, this paper is presented as a contribution for teachers and students to understand locomotion in the Spanish language.

Resumo A locomoção com membros implica diferentes desafios do tipo mecânico: em cada ciclo, os segmentos devem ser reposicionados anatomicamente, com fases de aceleração e desaceleração e a subsequente elevação e descenso do centro de massa. Dentro da locomoção humana, a marcha e a corrida são atividades fundamentais em todo o ciclo vital humano. Especificamente, a corrida é uma atividade muito estudada pelas ciências do esporte, medicina, fisioterapia ou cinesiologia, engenharia e biologia, devido à geração de alto impacto articular e muscular, trazendo consigo lesões e alterações no rendimento dos pacientes e esportistas. O constante estudo da locomoção reconheceu diferentes desafios de tipo fisiológico e mecânico, tanto na explicação de fenômenos como na análise destes. Este artigo busca aclarar conceitos através de textos clássicos, considerados básicos e importantes para entender as pesquisas posteriores. Além disso, são explicados diferentes parâmetros que servem para compreender a locomoção, tanto em estudos com humanos quanto com animais. O objetivo deste trabalho é fazer uma revisão da literatura, que se enfoca nos aspectos mecânicos, energéticos, no efeito do tamanho e nos diferentes padrões da locomoção, com seus modelos mecânicos. Finalmente, os autores esperam que este texto, em espanhol, seja uma contribuição para docentes e estudantes para a compreensão da locomoção.

Limiting Factors in Walking Performance of Subjects With COPD.

INTRODUCTION: Exercise intolerance is the most predominant symptom in patients with COPD. Nevertheless, it is unclear whether walking economy and gait variability are altered in these patients. Thus, our main objective was to compare the cost of transport and gait variability as a function of speed, including the self-selected walking speed, in subjects with COPD relative to healthy subjects. METHODS: 22 subjects, 11 with COPD (FEV1 = 45 ± 17% of predicted) and 11 age- and sex-matched healthy subjects undertook an evaluation that involved walking on a treadmill at 6 speeds (at 3.2 km/h, at a self-selected walking speed, and at 2 speeds below and 2 speeds above the self-selected walking speed) and measuring the cost of transport (the oxygen consumption normalized by mass and distance), gait variability, perceived dyspnea, and leg fatigue. RESULTS: In subjects with COPD, the cost of transport decreased with increasing walking speed, contrary to healthy subjects, who presented a minimum at the self-selected walking speed. No difference was found in cost of transport between the experimental groups at the same absolute velocity (P = .62). In subjects with COPD, dyspnea sensation rose above the self-selected walking speed, doubling at the maximal walking velocity (P = .03), and gait variability was higher at low speeds. CONCLUSION: Subjects with COPD choose their walking speed so as to keep the dyspnea sensation tolerable and to keep gait variability and cost of transport at an acceptable level. These outcomes suggest that interventions acting on dyspnea and gait pattern may increase patients' self-selected walking speed and improve their quality of life.

VELOCIDADE AUTOSSELECIONADA E IDEAL DA CAMINHADA DE AMPUTADOS TRANSFEMORAIS: SOLO E ESTEIRA / SELF-SELECTED AND OPTIMAL WALKING SPEED OF TRANSFEMORAL AMPUTEES: GROUND VS. TREADMILL / VELOCIDAD AUTOSELECCIONADA E IDEAL EN LA MARCHA DE AMPUTADOS TRANSFEMORALES: SUELO Y CINTA CAMINADORA

RESUMO Introdução: A velocidade de progressão é, em geral, determinada em pesquisas na área da locomoção. Objetivo: Comparar as medidas de velocidade autosselecionada no solo, na esteira rolante e a velocidade ideal estimada pelo número de Froude em sujeitos amputados transfemorais. Método: Primeiramente foi determinada a velocidade no solo; em seguida, realizou-se o teste na esteira, e a velocidade ideal foi estimada a partir dos dados antropométricos. Todos os sujeitos utilizavam joelho hidráulico e pé em fibra de carbono. Para comparação entre as velocidades foi realizada ANOVA de duas vias. Resultados: A velocidade autosselecionada na esteira foi menor (22%) do que no solo. Tanto a velocidade autosselecionada na esteira como a do solo foram 44% e 22% menores do que a velocidade ideal estimada, respectivamente. Conclusão: As velocidades analisadas no presente estudo foram diferentes, provavelmente, devido à variação dos parâmetros cinemáticos.

ABSTRACT Introduction: The speed of progression is generally determined in researches in the field of locomotion. Objective: To compare the self-selected velocity measurements on the ground, on treadmill and the optimal speed estimated by the Froude number in subjects with transfemoral amputation. Methods: First, the ground speed was determined; then the treadmill test was performed, and the optimal speed was estimated from anthropometric data. All subjects had hydraulic knee and carbon fiber foot. To compare the speeds, we used the two-way ANOVA. Results: The self-selected speed in the treadmill was lower (22%) compared with the ground. Both the self-selected speed in treadmill as ground were 44% and 22% lower than the estimated optimum speed, respectively. Conclusion: The speeds analyzed in this study were different, probably due to the variation of the kinematic parameters.

RESUMEN Introducción: La velocidad de progresión es generalmente determinada en investigaciones en el ámbito de la locomoción. Objetivo: Comparar las mediciones de la velocidad autoseleccionada en el suelo, en la cinta caminadora y la velocidad ideal estimada por el número de Froude en sujetos con amputación transfemoral. Métodos: En primer lugar, se determinó la velocidad en el suelo; después, se realizó la prueba en la cinta caminadora, y la velocidad ideal fue estimada a partir de los datos antropométricos. Todos los sujetos tenían rodilla hidráulica y pie en fibra de carbono. Para comparar las velocidades, se utilizó el ANOVA de dos vías. Resultados: La velocidad autoseleccionada en la cinta caminadora fue menor (22%) que en el suelo. Tanto la velocidad autoseleccionada en la cinta caminadora como la del suelo fueron 44% y 22% menores a la velocidad ideal estimada, respectivamente. Conclusión: Las velocidades analizadas en el presente estudio fueron diferentes, probablemente debido a la variación de los parámetros cinemáticos.

The pendular mechanism does not determine the optimal speed of loaded walking on gradients.

The pendular mechanism does not act as a primary mechanism in uphill walking due to the monotonic behavior of the mechanical energies of the center of mass. Nevertheless, recent evidence shows that there is an important minimization of energy expenditure by the pendular mechanism during walking on uphill gradients. In this study, we analyzed the optimum speed (OPT) of loaded human walking and the pendulum-like determining variables (Recovery R, Instantaneous pendular re-conversion Rint, and Congruity percentage %Cong). Ten young men walked on a treadmill at five different speeds and at three different treadmill incline gradients (0, +7 and +15%), with and without a load carried in their backpacks. We used indirect calorimetry and 3D motion analysis, and all of the data were analyzed by computational algorithms. Rint increased at higher speeds and decreased with increasing gradient. R and %Cong decreased with increasing gradient and increased with speed, independent of load. Thus, energy conversion by the pendular mechanism during walking on a 15% gradient is supported, and although this mechanism can explain the maintenance of OPT at low walking speeds, the pendular mechanism does not fully explain the energy minimization at higher speeds.

Comparação do consumo energético e de aspectos mecânicos da caminhada de amputados transfemurais que utilizam prótese com microprocessador ou convencional: uma revisão / Comparación del consumo de energía e los aspectos mecánicos de la caminata con prótesis transfemoral amputado basado en un microprocesador o convencional: una revisión / Comparison of energy consuption and mechanical aspects of transfemural amputee gait using prosthesis with the microprocessor and conventional knee: a review

A locomoção humana é o resultado de torques advindos de forças externas e internas. É um movimento complexo, cuja otimização minimiza o dispêndio energético. Existem restrições estruturais, como a amputação que influenciam a mecânica da locomoção e, por conseguinte o gasto energético. Neste artigo serão revisados temas relacionados à influência do tipo de prótese no consumo de oxigênio e nos aspectos biomecânicos da caminhada de amputados.