Instrumental Evaluation of the Posture

Abstract

Most common human activities require the ability to stabilize the human body in upright stance, to counteract perturbations and to allow voluntary movements, according to gravitational forces. The Standing human is an unstable physical structure. To counteract the effects of gravity and comply with the requirements to stabilize the body during voluntary movements there is a continuous modulation of motor activity, especially in so-called anti-gravity muscles, based on the also continuously changing afferent sensory information (Fig. 1). The postural control of the Standing human can therefore be considered in part adynamic feedbackcontrol [1]. Furthermore, based on experience and Visual information, the Standing human may foresee perturbations or changing requirements in advance, thus adding a substantial degree of anticipatory or feed-forward control [2]. To evaluate the significance on postural control of observations or test results it is necessary to bear in mind the physiological background and ability to maintain upright stance. Postural control cannot be considered a strictly hierarchical System but rather is characterized by decentralized or local decisions in a way which allows comparisons with the populär algorithms of neural networks [2]. Furthermore, there is a substantial amount of redundancy [2, 3].