A phenomenological model of muscle energy expenditure developed in part I of the paper, is utilized as a physiological cost function to estimate the muscle forces during normal locomotion. The model takes into account muscular behaviors typically observed during human gait, such as submaximal activation, variable muscular contraction conditions and muscular fiber type. The solution of the indeterminate biomechanical problem is obtained by integrating multibody dynamics and the global static optimization technique that considers the whole motion. The results for an application case indicate the important role of muscle groups in coordinating multijoint motion with the objective of minimizing metabolic costs of transport during locomotion.
Within the framework of multibody dynamics, a 3D large scale neuromusculoskeletal model of the human body is presented. To characterize the dynamics of skeletal muscle, a phenomenological model of energy expenditure was developed for estimating energy consumption during normal locomotion. Such model is able for predicting thermal and mechanical energy liberation under submaximal activation, muscle fiber type, and varying contractile conditions, typically observed in human motion. Future formulations of the indeterminate biomechanical problem, solved through the physiological criteria of minimization of metabolical cost of transport during gait, should consider the role of muscle groups in coordinating multijoint motion. Such an approach is presented in part II of the paper.
La correcta evaluación del movimiento articular a través de sistemas de análisis del movimiento depende, entre otros factores, de la correcta colocación de los marcadores reflectantes sobre los sujetos analizados. En el modelo convencional de marcha, de los 15 marcadores de miembro inferior, la mayoría se localizan en puntos anatómicos fáciles de localizar y que tienen poca posibilidad de error. Sin embargo, hay dificultad en otros, como el de la articulación de la rodilla y, sobre todo, en los del muslo y pierna.
En el estudio, se empleó un sistema VICON 460, con el que se analizó la cinemática de miembro inferior de 5 sujetos adultos sanos (2 mujeres, 3 varones). Para evaluar los movimientos articulares se empleó el modelo convencional de marcha. Determinada la posición correcta de los marcadores en cada sujeto, se procedió a la variación por separado de los marcadores de la rodilla, el muslo y la pierna, moviendo cada uno 15 mm anterior y posteriormente con relación a la posición inicial.
Estos pequeños desplazamientos producen importantes variaciones en los resultados cinemáticos obtenidos. Entre ellas en el varo-valgo de rodilla, parámetro que es de gran utilidad a la hora de detectar errores en la colocación de los marcadores.
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