دانلود رایگان ترجمه مقاله تحلیل و تفسیر نیروهای واکنشی زمینی در قدم زنی نرمال (نشریه Wseas 2009)

تحلیل و تفسیر نیروهای واکنشی زمینی در قدم زنی نرمال

Analysis and Interpretation of Ground Reaction Forces in Normal Gait

Abstract

The locomotion biomechanics study provides very extensive and interesting material for investigating the physiological process involved and the neural mechanisms controlling the systems. Gait analysis – the systematic analysis of locomotion – is used today for pretretment assessment, surgical decision making, postoperative follow-up, and management of both adult and young patients. Over the past few decades, multiple advances in bioengineering technology have permited precise analysis of many specific gait characteristics, such as joint angles, angular velocities and angular accelerations (kinematic analysis), as well as ground reaction forces, joint forces, moments and powers (kinetic analysis); electromyographic activity and energy consumption. Sophisticated gait analysis equipment can generate a visible force vector on an oscilloscope screen and superimpose it simultaneously on a photograph of a gait subject. Visualizing ground reaction forces helps us understand the effect they are having on the body in walking. If we have a full kinematic description, accurate anthropometric measures, and the external forces, we can calculate the joint reaction forces and musle moments. This predicition, called the inverse solution, is a very powerful tool in gaining insight into the net summation of all muscle activity at each joint. In this paper, we present and discuss the results of a ground reaction force analysis, conducted using the data samples of 40 voluntary subjects from our faculty student and employee population, differing in age, sex, height and weight, measured by the AMTI force platform.

1 Introduction

Kinetics by definition deals with those variables that are the cause of the specific walking or running pattern that we can observe or measure with cameras [1]. Kinetic (dynamic) movement quantities encompass forces and moments of force that are developed during movement between a body and its surrroundings, as well as internal forces and moments, the mechanical power patterns (rate of generation or absorbtion by muscles, or rate of transfer between segments) or energy patterns (segment or total body) [5]. Transducers have been developed that can be implanted surgically to measure the force exerted by a muscle at the tendon. However, such techniques have only applications in animal experiments and even then to a limited extent. If a measurement procedure is to be noninvasive, the measurement of the remaining (internal) kinetic quantities of human movement is practically impossible. It therefore remains to calculate the joint reaction forces and muscle moments indirectly, using available kinematic description, accurate anthropometric measures and the external forces. This prediction is called an inverse solution and it is a very powerful tool in gaining insight into the net summation of all muscle activity at each joint. Walking and running, the most natural forms of human locomotion, have often been the subject of ground reaction force measurements. As a part of the comprehensive research into healthy and pathological gait, Saunders [16] made the studies comparing the vertical ground reaction force signal components during stance phase in a healthy and unhealthy leg, specifically gait pathology resulting from a fused hip. The signals differed significantly because the remaining normal segments of the attacked extremity are only able to partially compensate for the loss of the hip joint function. Hallet [10] researched the pathophysiology of posture and gait in individuals with celebellar ataxia. They used the AMTI platform and presented the signals of the ground reaction force vertical component of healthy subject and of a patient. The comparison revealed that there is a appreciable irregularity and weak formation of the initial phase of the force signal in the patient. Other authors have focused their efforts on the research of characteristic biomechanical features (by means of EMG) of the locomotor system during normal gait and running, specifically the transition between these two modes of locomotion. In their article, Nilsson and colleagues [5, 13] presented the corresponding ground reaction force signals from two healthy subjects, at four different walking and running speeds, measured on the Kistler platform. Subjects wore athletic footwear. The results revealed the differences in ground reaction force signal waveforms in walking and running. In gait, as well as running, ground reaction force signals reflect an increase in the movement speed through the even larger increase in peak values and a shortening of signal duration. Andriacchi [15] showed that there was a good correlation in some of the peaks of ground reaction forces and velocity of walking. Music et al. [2, 3] proposed a method for measuring ground reaction forces during sit – to – stand motion using inertial sensors and a human body model. The proposed method fuses data from inertial sensors and the data from three – segment human body model using Extended Kalman filtering technique (EKF) which alleviates some of the drawbacks usually associated with inertial sensors. Dynamic human body model, incorporating shank, thigh and HAT (Head – Arms –Trunk) segments, was constructed based on principles of Lagrangian dynamics and the moments required in obtained model equations were calculated based on the EKF last best estimate and Newton – Euler inverse dynamic approach. Data on the foot’s center of pressure path during support phase in gait and running reveal interesting additional information. Besides vertical forces, Cavangh [13] researched the center of pressure paths during support in long-distance runners and discussed the results of the measured center of pressure paths made by two groups of runners differing significantly in their contact techniques. The first group was made of runners who realized the initial contact with the rear of the foot, and in the second group were those that made the initial contact with the mid – part of their foot. The implications of these measurements are interesting in connection with observing trauma caused by running – the study showed that the mid – foot strikers are exposed mostly to injuries and stress since they land relatively flat – footedly and the foot is not prepared for such loading. The goal of this study was to make the comparison of the ground reaction force features between left and right leg during normal gait cycle. Single force platform was set up to measure barefoot, isolated steps. 40 student and employee voluntary subjects, differing in age, sex, height and weight, took part in the study. Data from this research were statistically processed and the results are presented in this paper.