Efeitos do nível de estabilização e da estruturação da prática na adaptação a pertubações mecânicas imprevisíveis

Abstract

Motor adaptation is related with the ability in how to use the structures of motor control to predict or modify the motor planning according to the context and the level of performance stabilization. The formation of control structures, as well as the recalibration and the combination of them, seems to be conditioned to the way in which the practice is scheduled. In this manner, the practice of only one particular skill, such as intercepting a moving target using an effector with just one weight, leads to the formation of Internal Models (MIs) with a limited capacity for generalization. On the other hand, the practice with greater variation increases this ability. Following this assumption, the present study has two aims. Firstly, to investigate the effects of two different levels of performance stabilization (e.g. level of ability) to unpredictable perturbations. Further, to investigate the control in function of different levels of stabilization and practice schedules. With this end, two experiments were performed [experiment I – four groups (n=56); experiment II – two groups (n=22)], in which the participants underwent a pre-exposure phase, and later (24 hours after) an exposure phase with mechanical perturbations (i.e. changing the external load). The task was to move a physical effector at a 200-250ms in order to intercept a virtual moving target projected on a screen perpendicularly to the virtual effector (v=145cm/s). The analysis was performed in both pre-exposure and exposure phase. The results revealed that the achieve of the level of stabilization with constant and random practice lead to the formation of structures control that use different strategies during the process of skill acquisition, which was even more prominent in the random practice. The achievement of the level of performance specialization, from constant practice, random practice and combined practice (Constant-Random and Random-Constant) seem to lead to the formation of control structures that use similar strategies and reflect in an improved performance when faced to unpredictable mechanical perturbation. Therefore, the findings of this study allow us to conclude that not only the level of stabilization of performance, but also the practice schedule influences the formation of structures control and consequently the motor adaptation.