Modelo biomecânico de corpo inteiro com coordenadas naturais para análise de movimento humano

Abstract

Computational biomechanical models allow estimating variables which cannot be measured directly in a noninvasive way. Here, the push-up exercise was analyzed using a whole body model, which can be considered as a closed-loop multibody system, with a focus on the upper limbs and trunk. The movement was performed by 12 healthy volunteers, while four force platforms collected hands and feet floor reaction forces and torques. Kinematics was measured by a reflective-markers system and joint angles calculated by a custom kinematical model. A multibody system model, based on redundant natural coordinates, was developed, containing 21 segments and 252 generalized coordinates. Anatomical joints were modeled through ball-and-socket, Cardan, hinge and contact surface kinematical pairs. For direct dynamics simulation, the model comprised 44 degrees of freedom and, for inverse dynamics analysis, 66. The inverse dynamics results were validated by an alternative formulation based on NewtonEuler equations, presenting maximum errors of (1,4±0,4) N/kg and (0,75±0,21) Nm/kg for joint reaction forces and net torques, respectively. Different torque and force patterns were observed whether the exercise was performed with the arms adducted or abducted. Such patterns allow inferring which arm configuration is likely to cause overload injuries in specific joints and degrees of freedom